1. Field of the Invention
The present invention relates to retroviral protease inhibitors and, more particularly, relates to novel compounds and a composition and method for inhibiting retroviral proteases. This invention, in particular, relates to bis-sulfonamide-containing hydroxyethylamine protease inhibitor compounds, a composition and method for inhibiting retroviral proteases such as human immunodeficiency virus (HIV) protease and for treating a retroviral infection, e.g., an HIV infection. The subject invention also relates to processes for making such compounds as well as to intermediates useful in such processes.
2. Related Art
During the replication cycle of retroviruses, gag and gag-pol gene transcription products are translated as proteins. These proteins are subsequently processed by a virally encoded protease (or proteinase) to yield viral enzymes and structural proteins of the virus core. Most commonly, the gag precursor proteins are processed into the core proteins and the pol precursor proteins are processed into the viral enzymes, e.g., reverse transcriptase and retroviral protease. It has been shown that correct processing of the precursor proteins by the retroviral protease is necessary for assembly of infectious virons. For example, it has been shown that frameshift mutations in the protease region of the pol gene of HIV prevents processing of the gag precursor protein. It has also been shown through site-directed mutagenesis of an aspartic acid residue in the HIV protease active site that processing of the gag precursor protein is prevented. Thus, attempts have been made to inhibit viral replication by inhibiting the action of retroviral proteases.
Retroviral protease inhibition typically involves a transition-state mimetic whereby the retroviral protease is exposed to a mimetic compound which binds (typically in a reversible manner) to the enzyme in competition with the gag and gag-pol proteins to thereby inhibit specific processing of structural proteins and the release of retroviral protease itself. In this manner, retroviral replication proteases can be effectively inhibited.
Several classes of compounds have been proposed, particularly for inhibition of proteases, such as for inhibition of HIV protease. Such compounds include hydroxyethylamine isosteres and reduced amide isosteres. See, for example, EP 0 346 847; EP 0 342,541; Roberts et al, xe2x80x9cRational Design of Peptide-Based Proteinase Inhibitors,xe2x80x9d Science, 248, 358 (1990); and Erickson et al, xe2x80x9cDesign Activity, and 2.8 xc3x85 Crystal Structure of a C2 Symmetric Inhibitor Complexed to HIV-1 Protease,xe2x80x9d Science, 249, 527 (1990). Sulfonamide-containing, aminosulfonamide-containing and urea-containing hydroxyethylamine compounds and intermediates useful as retroviral protease inhibitors have been disclosed in WO94/05639, WO94/10136, WO94/10134, WO94/04493, WO94/04492, WO 93/23368, and WO93/23379.
Several classes of compounds are known to be useful as inhibitors of the proteolytic enzyme renin. See, for example, U.S. Pat. No. 4,599,198; U.K. 2,184,730; G.B. 2,209,752; EP 0 264 795; G.B. 2,200,115 and U.S. SIR H725. Of these, G.B. 2,200,115, GB 2,209,752, EP 0 264,795, U.S. SIR H725 and U.S. Pat. No. 4,599,198 disclose urea-containing hydroxyethylamine renin inhibitors. EP 468 641 discloses renin inhibitors and intermediates for the preparation of the inhibitors, which include sulfonamide-containing hydroxyethylamine compounds, such as 3-(t-butoxycarbonyl)amino-cyclohexyl-1-(phenylsulfonyl)amino-2(5)-butanol. G.B. 2,200,115 also discloses sulfamoyl-containing hydroxyethylamine renin inhibitors, and EP 0264 795 discloses certain sulfonamide-containing hydroxyethylamine renin inhibitors. However, it is known that, although renin and HIV proteases are both classified as aspartyl proteases, compounds which are effective renin inhibitors generally cannot be predicted to be effective HIV protease inhibitors.
The present invention is directed to virus inhibiting compounds and compositions. More particularly, the present invention is directed to retroviral protease inhibiting compounds and compositions, to a method of inhibiting retroviral proteases, to processes for preparing the compounds and to intermediates useful in such processes. The subject compounds are characterized as bis-sulfonamide-containing hydroxyethylamine inhibitor compounds.
In accordance with the present invention, there is provided a retroviral protease inhibiting compound of the formula: 
or a pharmaceutically acceptable salt, prodrug or ester thereof, wherein
R1 represents hydrogen, xe2x80x94CH2SO2NH2, xe2x80x94CH2CO2CH3, xe2x80x94CO2CH3, xe2x80x94CONH2, xe2x80x94CH2C(O)NHCH3, xe2x80x94C(CH3)2(SH), xe2x80x94C(CH3)2(SCH3), xe2x80x94C(CH3)2(S[O]CH3), xe2x80x94C(CH3)2(S[O]2CH3), alkyl, haloalkyl, alkenyl, alkynyl cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, aminosulfonylalkyl, N-alkylaminosulfonylalkyl, N,N-dialkylaminosulfonylalkyl, aryl, aralkyl, heteroaryl or heteroaralkyl radicals, an amino acid side chain of asparagine, lysine, aspartic acid, aspartic acid methyl ester, methionine or the sulfoxide (SO) or sulfone (SO2) derivatives thereof, S-methyl cysteine or the sulfoxide (SO) or sulfone (SO2) derivatives thereof, isoleucine, allo-isoleucine, alanine, leucine, tert-leucine, phenylalanine, ornithine, histidine, norleucine, glutamine, threonine, allo-threonine, serine, O-alkyl serine, beta-cyano alanine or valinie;
R2 represents alkyl, aryl, cycloalkxyl, cycloalkylalkyl, aralkyl, heteroaryl or heteroaralkyl radicals, which radicals are optionally substituted with one or more alkyl, halogen, xe2x80x94NO2, xe2x80x94CN, xe2x80x94CF3, xe2x80x94OR9 or xe2x80x94SR9 radicals, wherein R9 represents hydrogen, alkyl, aryl, heteroaryl, cycloalkyl or heterocyclo radicals;
R3 represents hydrogen, alkyl, haloalkyl, alkenyl, alkynyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heteroaryl, heterocycloalkyl, aryl, aralkyl, heteroaralkyl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof, aminoalkyl or N-mono- or N,N-disubstituted aminoalkyl radicals, wherein said substituents are alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocyclo, or heterocycloalkyl radicals;
R4 represents alkyl, haloalkyl, alkenyl, alkynyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heteroaryl, heterocycloalkyl, aryl, aralkyl, aralkenyl, heteroaralkyl, alkoxycarbonylaminoheteroaryl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof, aminoalkyl or N-mono- or N,N-disubstituted aminoalkyl radicals, wherein said substituents are alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocyclo, or heterocycloalkyl radicals, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof;
R6 represents hydrogen or alkyl radicals;
each R7 independently represents carboxy, amidino or N-alkylamidino radicals, or radicals as defined for R1; or R7 together with R1 and the carbon atoms to which R1 and R7 are attached, represent cycloalkyl or heterocyclo radicals;
each R1 independently represents hydrogen or alkyl radicals;
R10 and R11 each independently represent hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, heteroarylcarbonylalkyl, arylcarbonylalkyl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof, aminoalkyl or N-mono- or N,N-disubstituted aminoalkyl radicals, wherein said substituents are alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocyclo or heterocycloalkyl radicals; or R10 and R11 together with the nitrogen to which they are attached represent heterocyclo, heteroaryl, aralkylheteroaryl, aralkylheterocyclo, heteroaralkylheteroaryl or heteroaralkylheterocyclo radicals;
x and w each represent 0, 1 or 2;
t represents 0-6; and
Y represents O, S or NH.
A family of compounds of particular interest within Formula I are compounds embraced by Formula II: 
wherein
R1 represents hydrogen, xe2x80x94CH2SO2NH2, xe2x80x94CH2CO2CH3, xe2x80x94CO2CH3, xe2x80x94CONH2, xe2x80x94CH2C(O)NHCH3, xe2x80x94C(CH3)2(SH), xe2x80x94C(CH3)2(SCH3), xe2x80x94C(CH3)2(S[O]CH3), xe2x80x94C(CH3)2(S[O]2CH3), alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aminosulfonylalkyl, N-alkylaminosulfonylalkyl, N,N-dialkylaminosulfonylalkyl or heteroaralkyl radicals, or an amino acid side chain of asparagine, lysine, aspartic acid, aspartic acid methyl ester, methionine or the sulfoxide (SO) or sulfone (SO2) derivatives thereof, S-methyl cysteine or the sulfoxide (SO) or sulfone (SO2) derivatives thereof, ornithine, leucine, isoleucine, norleucine, allo-isoleucine, alanine, phenylalanine, histidine, tert-leucine, glutamine, threonine, allo-threonine, serine, O-alkyl serine, beta-cyano alanine or valine;
R2 represents alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heteroaryl or heteroaralkyl radicals, which radicals are optionally substituted with one or more alkyl, halogen, xe2x80x94NO2, xe2x80x94CN, xe2x80x94CF3, xe2x80x94OR9 or xe2x80x94SR9 radials, wherein R9 represents hydrogen, alkyl, aryl, heteroaryl, cycloalkyl or heterocyclo radicals;
R3 represents hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof, aminoalkyl or N-mono- or N,N-disubstituted aminoalkyl radicals, wherein said substituents are alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocyclo or heterocycloalkyl radicals;
R4 represents alkyl, alkenyl, alkynyl, haloalkyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, heteroaryl, heteroaralkyl, alkoxycarbonylaminoheteroaryl, aryl, aralkyl, aralkenyl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof, aminoalkyl or N-mono- or N,N-disubstituted aminoalkyl radicals, wherein said substituents are alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocyclo or heterocycloalkyl radicals, thioalkyl, alkylthioalkyl or arythioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof:
R6 represents hydrogen or alkyl radicals;
each R7 independently represents hydrogen, xe2x80x94CH2SO2NH2, xe2x80x94CH2CO2CH3, xe2x80x94CO2CH3, xe2x80x94CONH2, xe2x80x94CH2C(O)NHCH3, xe2x80x94C(CH3)2(SH), xe2x80x94C(CH3)2(SCH3), xe2x80x94C(CH3)2(S[O]CH3), xe2x80x94C(CH3)2(S[O]2CH3), carboxy, amidino, N-alkylamidino, alkyl, aryl or aralkyl radicals; or R7 together with R1 and the carbon atoms to which R1 and R7 are attached, represent cycloalkyl or heterocyclo radicals;
each R8 independently represents hydrogen or alkyl radicals;
R10 represents hydrogen, alkyl, aryl, aralkyl, heterocyclo, heterocycloalkyl, heteroaryl or heteroaralkyl radicals;
R11 represents hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, heteroarylcarbonylalkyl, arylcarbonylalkyl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof, aminoalkyl or N-mono- or N,N-disubstituted aminoalkyl radicals, wherein said substituents are alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocyclo or heterocycloalkyl radicals; or R10 and R11 together with the nitrogen to which they are attached represent heterocyclo, heteroaryl, aralkylheteroaryl, aralkylheterocyclo, heteroaralkylheteroaryl or heteroaralkylheterocyclo radicals;
t represents 0-4; and
Y represents O, S or NH.
A more preferred family of compounds within Formula II consistes of compounds wherein:
R1 represents hydrogen, xe2x80x94CH2SO2NH2, xe2x80x94CH2CO2CH3, xe2x80x94CO2CH3, xe2x80x94CONH2, xe2x80x94CH2C(O)NHCH3, xe2x80x94C(CH3)2(SH), xe2x80x94C(CH3)2(SCH3), xe2x80x94C(CH3)2(S[O]CH3), xe2x80x94C(CH3)2(S[O]2CH3), alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aminosulfonylalkyl, N-alkylaminosulfonylalkyl, N,N-dialkylaminosulfonylalkyl or heteroaralkyl radicals, or an amino acid side chain of asparagine, lysine, aspartic acid, aspartic acid methyl ester, methionine or the sulfoxide (SO) or sulfone (SO2) derivatives thereof, S-methyl cysteine or the sulfoxide (SO) or sulfone (SO2) derivatives thereof, ornithine, leucine, isoleucine, norleucine, allo-isoleucine, alanine, phenylalanine, histidine, tert-leucine, glutamine, threonine, allo-threonine, serine, O-alkyl serine, beta-cyano alanine or valine;
R2 represents alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl or heteroaralkyl radicals, which radicals are optionally substituted with one or more alkyl, halogen, xe2x80x94NO2, xe2x80x94CN, xe2x80x94CF3, xe2x80x94OR9 or xe2x80x94SR9 radicals, wherein R9 represents hydrogen, alkyl, aryl, heteroaryl, cycloalkyl or heterocyclo radicals;
R3 represents alkyl, alkenyl, alkynyl, haloalkyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, N-alkylaminoalkyl, N,N-dialkylaminoalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, thioalkyl, alkylthioalkyl or arylthioalkyl radicals or the corresponding sulfone or sulfoxide derivatives thereof;
R4 represents alkyl, alkenyl, alkynyl, haloalkyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, heteroaryl, heteroaralkyl, alkoxycarbonylaminoheteroaryl, aryl, aralkyl or aralkenyl radicals;
R6 represents hydrogen or alkyl radicals;
each R7 independently represents hydrogen, xe2x80x94CO2CH3, xe2x80x94CONH2, carboxy, amidino, N-alkylamidino, alkyl, aryl or aralkyl radicals; or R7 together with R1 and the carbon atoms to which R1 and R7 are attached, represent cycloalkyl or heterocyclo radicals;
each R8 independently represents hydrogen or alkyl radicals;
R10 represents hydrogen, alkyl, aralkyl or heteroaralkyl radicals;
R11 represents hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, N-alkylaminoalkyl, N,N-dialkylaminoalkyl, cycloalkyl, cycloalkylalkyl, heterocyclo, heterocycloalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, heteroarylcarbonylalkyl or arylcarbonylalkyl radicals; or R10 and R11 together with the nitrogen to which they are attached represent heterocyclo, heteroaryl, aralkylheteroaryl, aralkylheterocyclo, heteroaralkylheteroaryl or heteroaralkylheterocyclo radicals;
t represents 0-4; and
Y represents O or S.
Of higest interest are compounds within Formula II wherein
R1 represents hydrogen, xe2x80x94CH2C(O)NHCH3, xe2x80x94C(CH3)2(SCH3), C(CH3)2(S[O]CH3), xe2x80x94C(CH3)2(S[O]2CH3), methyl, ethyl, isopropyl, iso-butyl, sec-butyl, tert-butyl, propenyl or propargyl radicals, or an amino acid side chain of asparagine, S-methyl cysteine, isoleucine, allo-isoleucine, alanine, tert-leucine or valine;
R2 represents CH3SCH2CH2xe2x80x94, iso-butyl, n-butyl, benzyl, fluorobenzyl, naphthylmethyl, cyclohexylmethyl, phenylthiomethyl or naphthylthiomethyl radicals;
R3 represents isoamyl, iso-butyl, propyl, n-butyl, cyclohexyl, cycloheptyl, cyclohexylmethyl, cyclopentylmethyl, cyclopropylmethyl, pyridylmethyl or benzyl radicals;
R4 represents methyl, phenyl, pyridyl, furyl, imidazolyl, ethylenedioxyphen-4-yl, methylenedioxyphen-5-yl, ethylenedioxyphenyl, benzothiazolyl, benzopyranyl, benzimidazolyl, benzofuryl, 2,3-dihydrobenzofuryl, benzoxazolyl, oxazolyl, thiazolyl or thiophenyl radicals, optionally substituted with one or more methyl, methoxy, fluoro, chloro, hydroxy, amino, nitro or methoxycarbonylamino radicals;
R6 represents hydrogen or methyl radicals;
each R7 independently represents hydrogen, xe2x80x94CO2CH3, xe2x80x94CONH2 or methyl radicals; or R7 together with R1 and the carbon atoms to which R1 and R7 are attached represent cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl radicals;
each R8 independently represents hydrogen or methyl radicals;
R10 and R11 each independently represent hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pyrolylethyl, piperidinylethyl, pyrrolidinylethyl, morpholinylethyl, thiomorpholinylethyl, pyridylmethyl, methylaminoethyl, dimethylaminoethyl, phenyl, benzyl or diphenylmethyl radicals; or R10 and R11 together with the nitrogen to which they are attached represent piperidinyl, morpholinyl, thiomorpholinyl or sulfone or sulfoxide derivatives thereof, piperazinyl, pyrrolidinyl or pyrrolyl radicals, or N-(alkyl)piperazinyl, N-(aralkyl)piperazinyl, N-(heteroaralkyl)piperazinyl or N-(heterocycloalkyl) piperazinyl radicals, such as N-methylpiperazinyl, N-ethylpiperazinyl, N-benzylpiperazinyl, N-(pyridylmethyl)piperazinyl, N-(tetrahydrothienylmethyl)piperazinyl, N-(thiazolylmethyl)piperazinyl, N-(furylmethyl)piperazinyl, N-(benzoxazolylmethyl)piperazinyl, N-(piperidinylethyl)piperazinyl, N-(morpholinoethyl)piperazinyl and the like;
t represents 0 or 1; and
Y represents O or S.
The absolute stereochemistry of the carbon atom of xe2x80x94CH(OH)xe2x80x94 group is preferably (R). The absolute stereochemistry of the carbon atom of xe2x80x94CH(R1)xe2x80x94 group is preferably (S). The absolute stereochemistry of the carbon atom of xe2x80x94CH(R2)xe2x80x94 groups is preferably (S).
As utilized herein, the term xe2x80x9calkylxe2x80x9d, alone or in combination, means a straight-chain or branched-chain alkyl radical containing preferably from 1 to 10 carbon atoms, more preferably from 1 to 8 carbon atoms, most preferably 1-5 carbon atoms. Examples of such radicals include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, hexyl, octyl and the like. The term xe2x80x9cthioalkylxe2x80x9d means an alkyl radical as defined above which is substituted by at least one xe2x80x94SH group. xe2x80x9cAlkylthioalkylxe2x80x9d and xe2x80x9carylthioalkylxe2x80x9d means an alkyl radical as defined above which is substituted by at least one alkyl-S and aryl-Sxe2x80x94, respectively, where alkyl and aryl are as defined herein. Examples of thioalkyl, alkylthioalkyl and arylthioalkyl are xe2x80x94CH2SCH2CH3, xe2x80x94CH2CH2SH, xe2x80x94C(CH3)2SH, xe2x80x94C(CH3)2SCH3, xe2x80x94(CH2)2SCH3, xe2x80x94CH2S-phenyl and the like. The corresponding sulfoxide and sulfone of such thioalkyls are xe2x80x94CH2S(O)CH2CH3, xe2x80x94C(CH3)2S(O)CH3, xe2x80x94C(CH3)2S(O)CH3, xe2x80x94CH2S(O)2CH2CH3, xe2x80x94C(CH3)2S(O)2CH3, xe2x80x94CH2S(O)phenyl, xe2x80x94CH2xe2x80x94S(O)2phenyl, xe2x80x94C(CH3)2S(O)2CH3 and the like. The term xe2x80x9calkenylxe2x80x9d, alone or in combination, means a straight-chain or branched-chain hydrocarbon radial having one or more double bonds and containing preferably from 2 to 10 carbon atoms, more preferably from 2 to 8 carbon atoms, most preferably from 2 to 5 carbon atoms. Examples of suitable alkenyl radicals include ethenyl, propenyl, 2-methylpropenyl, 1,4-butadienyl and the like. The term xe2x80x9calkynylxe2x80x9d, alone or in combination, means a straight-chain or branched chain hydrocarbon radical having one or more triple bonds and containing preferably from 2 to 10 carbon atoms, more preferably from 2 to 5 carbon atoms. Examples of alkynyl radicals include ethynyl, propynyl, (propargyl), butynyl and the like. The term xe2x80x9calkoxyxe2x80x9d, alone or in combination, means an alkyl ether radical wherein the term alkyl is as defined above. Examples of suitable alkyl ether radicals include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, iso-butoxy, sec-butoxy, tert-butoxy and the like. The term xe2x80x9ccycloalkylxe2x80x9d, alone or in combination, means a saturated or partially saturated monocyclic, bicyclic or tricyclic alkyl radical wherein each cyclic moiety contains preferably from 3 to 8 carbon atom ring members, more preferably from 3 to 7 carbon atom ring members, most preferably from 5 to 6 carbon atom ring members, and which may optionally be a benzo fused ring system which is optionally substituted as defined herein with respect to the definition of aryl. Examples of such cycloalkyl radicals include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, octahydronaphthyl, 2,3-dihydro-1H-indenyl, adamantyl and the like. xe2x80x9cBicyclicxe2x80x9d and xe2x80x9ctricyclicxe2x80x9d as used herein are intended to include both fused ring systems, such as naphthyl and xcex2-carbolinyl, and substituted ring systems, such as biphenyl, phenylpyridyl, naphthyl and diphenylpiperazinyl. The term xe2x80x9ccycloalkylalkylxe2x80x9d means an alkyl radical as defined above which is substituted by a cycloalkyl radical as defined above. Examples of such cycloalkylalkyl radicals include cyclopropylmethyl, cytlobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, 1-cyclopentylethyl, 1-cyclohexylethyl, 2-cyclopentylethyl, 2-cyclohexylethyl, cyclobutylpropyl, cyclopentylpropyl, cyclohexylbutyl and the like. The term xe2x80x9carylxe2x80x9d, alone or in combination, means a phenyl or naphthyl radical which is optionally substituted with one or more substituents selected from alkyl, alkoxy, halogen, hydroxy, amino, nitro, cyano, haloalkyl, carboxy, alkoxycarbonyl, cycloalkyl, heterocyclo, alkanoylamino, amido, amidino, alkoxycarbonylamino, N-alkylamidino, alkylamino, dialkylamino, N-alkylamido, N,N-dialkylamido, aralkoxycarbonylamino, alkylthio, alkylsulfinyl, alkylsulfonyl and the like. Examples of aryl radicals are phenyl, p-tolyl, 4-methoxyphenyl, 4-(tert-butoxy)phenyl, 3-methyl-4-methoxyphenyl, 4-fluorophenyl, 4-chlorophenyl, 3-nitrophenyl, 3-aminophenyl, 3-acetamidophenyl, 4-acetamidophenyl, 2-methyl-3-acetamidophenyl, 2-methyl-3-aminophenyl, 3-methyl-4-aminophenyl, 2-amino-3-methylphenyl, 2,4-dimethyl-3-aminophenyl, 4-hydroxyphenyl, 3-methyl-4-hydroxyphenyl, 1-naphthyl, 2-naphthyl, 3-amino-1-naphthyl, 2-methyl-3-amino-1-naphthyl, 6-amino-2-naphthyl, 4,6-dimethoxy-2-naphthyl, piperazinylphenyl and the like. The terms xe2x80x9caralkylxe2x80x9d and xe2x80x9caralkoxyxe2x80x9d, alone or in combination, means an alkyl or alkoxy radical as defined above in which at least one hydrogen atom is replaced by an aryl radical as defined above, such as benzyl, benzyloxy, 2-phenylethyl, dibenzylmethyl, hydroxyphenylmethyl, methylphenylmethyl, diphenylmethyl, diphenylmethoxy, 4-methoxyphenylmethoxy and the like. The term xe2x80x9caralkoxycarbonylxe2x80x9d, alone or in combination, means a radical of the formula aralkyl-Oxe2x80x94C(O)xe2x80x94 in which the term xe2x80x9caralkylxe2x80x9d has the significance given above. Examples of an aralkoxycarbonyl radical are benzyloxycarbonyl and 4-methoxyphenylmethoxycarbonyl. The term xe2x80x9caryloxylxe2x80x9d means a radical of the formula aryl-Oxe2x80x94 in which the term aryl has the significance given above. The term xe2x80x9calkanoylxe2x80x9d, alone or in combination, means an acyl radical derived from an alkanecarboxylic acid, examples of which include acetyl, propionyl, butyryl, valeryl, 4-methylvaleryl, and the like. The term xe2x80x9ccycloalkylcarbonylxe2x80x9d means an acyl radical of the formula cycloalkyl-C(O)xe2x80x94 in which the term xe2x80x9ccycloalkylxe2x80x9d has the significance give above, such as cyclopropylcarbonyl, cyclohexylcarbonyl, adamantylcarbonyl, 1,2,3,4-tetrahydro-2-naphthoyl, 2-acetamido-1,2,3,4-tetrahydro-2-naphthoyl, 1-hydroxy-1,2,3,4-tetrahydro-6-naphthoyl and the like. The term xe2x80x9caralkanoylxe2x80x9d, means an acyl radical derived from an aryl-substituted alkanecarboxylic acid such as phenylacetyl, 3-phenylpropionyl(hydrocinnamoyl), 4-phenylbutyryl, (2-naphthyl)acetyl, 4-chlorohydrocinnamoyl, 4-aminohydrocinnamoyl, 4-methoxyhydrocinnamoyl, and the like. The term xe2x80x9caroylxe2x80x9d means an acyl radical derived from an arylcarboxylic acid, xe2x80x9carylxe2x80x9d having the meaning given above. Examples of such aroyl radicals include substituted and unsubstituted benzoyl or napthoyl such as benzoyl, 4-chlorobenzoyl, 4-carboxybenzoyl, 4-(benzyloxycarbonyl)benzoyl, 1-naphthoyl, 2-naphthoyl, 6-carboxy-2 naphthoyl, 6-(benzyloxycarbonyl)-2-naphthoyl, 3-benzyloxy-2-naphthoyl, 3-hydroxy-2-naphthoyl, 3-(benzyloxyformamido)-2-naphthoyl, and the like. The terms xe2x80x9cheterocyclo,xe2x80x9d alone or in combination, means a saturated or partially unsaturated monocyclic, bicyclic or tricyclic heterocycle radical containing at least one nitrogen, oxygen or sulfur atom ring member; preferably, 1-4 nitrogen, oxygen or sulfur atom ring member; more preferably, 0-4 nitrogen, 0-2 oxygen and 0-2 sulfur atom ring member, but at least one such heteroatom; and having preferably 3 to 8 ring members in each ring, more preferably 3 to 7 ring members in each ring and most preferably 5 to 6 ring members in each ring. xe2x80x9cHeterocycloxe2x80x9d is intended to include sulfones, sulfoxides, N-oxides of tertiary nitrogen ring members, and carbocyclic fused and benzo fused ring systems. Such heterocyclo radicals may be optionally substituted on one or more carbon atoms by halogen, alkyl, alkoxy, hydroxy, oxo, aryl, aralkyl, heteroaryl, heteroaralkyl, amidino, N-alkylamidino, alkoxycarbonylamino, alkylsulfonylamino and the like, and/or on a secondary nitrogen atom (i.e., xe2x80x94NHxe2x80x94) by hydroxy, alkyl, aralkoxycarbonyl, alkanoyl, heteroaralkyl, phenyl or phenylalkyl and/or on a tertiary nitrogen atom (i.e., xe2x95x90Nxe2x80x94) by oxido. xe2x80x9cHeterocycloalkyxe2x80x9d means an alkyl radical as defined above in which at least one hydrogen atom is replaced by a heterocyclo radical as defined above, such as pyrrolidinylmethyl, tetrahydrothienylmethyl, pyridylmethyl and the like. The term xe2x80x9cheteroarylxe2x80x9d, alone or in combination, means an aromatic heterocyclo radical as defined above, which is optionally substituted as defined above with respect to the definitions of aryl and heterocyclo. Examples of such heterocyclo and heteroaryl groups are pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiamorpholinyl, pyrrolyl, imidazolyl (e.g., imidazol 4-yl, 1-benzyloxycarbonylimidazol-4-yl, etc.), pyrazolyl, pyridyl, (e.g., 2-(1-piperidinyl)pyridyl and 2-(4-benzylpiperazin-1-yl-1-pyridinyl, etc.), pyrazinyl, pyrimidinyl, furyl, tetrahydrofuryl, thienyl, tetrahydrothienyl and its sulfoxide and sulfone derivatives, triazolyl, oxazolyl, thiazolyl, indolyl (e.g., 2-indolyl, etc.), quinolinyl, (e.g., 2-quinolinyl, 3-quinolinyl, 1-oxido-2-quinolinyl, etc.), isoquinolinyl (e.g., 1-isoquinolinyl, 3-isoquinolinyl, etc.), tetrahydroquinolinyl (e.g., 1,2,3,4-tetrahydro-2-quinolyl, etc.), 1,2,3,4-tetrahydroisoquinolinyl (e.g., 1,2,3,4-tetrahydro-1-oxo-isoquinolinyl, etc.), quinoxalinyl, xcex2-carbolinyl, 2-benzofurancarbonyl, 1-,2-, 4- or 5-benzimidazolyl, methylenedioxyphen-4-yl, methylenedioxyphen-5-yl, ethylenedioxyphenyl, benzothiazolyl, benzopyranyl, benzofuryl, 2,3-dihydrobenzofuryl, benzoxazolyl, thiophenyl and the like. The term xe2x80x9cheteroatomxe2x80x9d means a nitrogen, oxygen or sulfur atom. The term xe2x80x9ccycloalkylalkoxycarbonylxe2x80x9d, means an acyl group derived from a cycloalkylalkoxycarboxylic acid of the formula cycloalkylalkyl-Oxe2x80x94COOH wherein cycloalkylalkyl has the meaning given above. The term xe2x80x9caryloxyalkanoylxe2x80x9d means an acyl radical of the formula aryl-O-alkanoyl wherein aryl and alkanoyl have the meaning given above. The term xe2x80x9cheterocycloalkoxycarbonyxe2x80x9d, means an acyl group derived from heterocycloalkyl-Oxe2x80x94COOH wherein heterocycloalkyl is as defined above. The term xe2x80x9cheterocycloalkanoylxe2x80x9d is an acyl radical derived from a heterocycloalkylcarboxylic acid wherein heterocyclo has the meaning given above. The term xe2x80x9cheterocycloalkoxycarbonylxe2x80x9d means an acyl radical derived from a heterocycloalkyl-Oxe2x80x94COOH wherein heterocyclo has the meaning given above. The term xe2x80x9cheteroaryloxycarbonylxe2x80x9d means an acyl radical derived from a carboxylic acid represented by heteroaryl-Oxe2x80x94COOH wherein heteroaryl has the meaning given above. The term xe2x80x9caminocarbonyxe2x80x9d, alone or in combination, means an amino-substituted carbonyl (carbamoyl) group wherein the amino group can be a primary, secondary or tertiary amino group containing substituents selected from alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl radicals and the like. The term xe2x80x9caminoalkanoylxe2x80x9d means an acyl group derived from an amino-substituted alkylcarboxylic acid wherein the amino group can be a primary, secondary or tertiary amino group containing substituents selected from alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl radicals and the like. The term xe2x80x9chalogenxe2x80x9d means fluorine, chlorine, bromine or iodine. The term xe2x80x9chaloalkylxe2x80x9d means an alkyl radical having the meaning as defined above wherein one or more hydrogens are replaced with a halogen. Examples of such haloalkyl radicals include chloromethyl, 1-bromoethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1,1,1-trifluoroethyl and the like. The term xe2x80x9cleaving groupxe2x80x9d (L) generally refers to groups readily displaceable by a nucleophile, such as an amine, a thiol or an alcohol nucleophile. Such leaving groups are well known in the art. Examples of such leaving groups include, but are not limited to, N-hydroxysuccinimide, N-hydroxybenzotriazole, halides, triflates, tosylates and the like. Preferred leaving groups are indicated herein where appropriate. The term xe2x80x9camino acid side chainxe2x80x9d means the side chain group, including the stereochemistry of the carbon to which it is attached, attached to the naturally occurring amino acid which distinguishes the amino acid from glycine. For example, the amino acid side chain of alanine is methyl, of histidine is imidazolylmethyl and phenylalanine is benzyl, and the attachment of such side chains to the compound of this invention retain the naturally occurring stereochemistry of the carbon to which it is attached. The following example illustrates the definition: 
Procedures for preparing the compounds of Formula I are set forth below. It should be noted that the general procedure is shown as it relates to preparation of compounds having the specified stereochemistry, for example, wherein the absolute stereochemistry about the hydroxyl group is designated as (R). However, such procedures are generally applicable to those compounds of opposite configuration, e.g., where the stereochemistry about the hydroxyl group is (S). In addition, the compounds having the (R) stereochemistry of the hydroxyl group can be utilized to produce those having the (S) stereochemistry. A compound having the (R) stereochemistry of the hydroxyl group can be inverted to the (S) stereochemistry using well-known methods. For example, the hydroxy group can be converted into a leaving group such as a mesylate or tosylate and reacting the leaving group with an oxide anion such as hydroxide, benzyloxide (followed by debenzylation) and the like, to produce an hydroxyl group with an (S) stereochemistry.
The compounds of the present invention represented by Formula I above can be prepared utilizing the following general procedure. This procedure is schematically shown in the following Schemes I-III: 
a) R3NH2; b) R4SO2Cl (or anhydride)+acid scavenger; c) deprotection; and d) coupling. 
a)R3NH2; b) R4SO2Cl (or anhydride)+acid scavenger; c) deprotection; and d) coupling. 
a) R3NH2; b) protection; c) deprotection; d) coupling; e) deprotection; and f) R4SO2Cl (or anhydride).
An N-protected chloroketone derivative of an amino acid having the formula: 
wherein P represents an amino protecting group, and R2 is as defined above, is reduced to the corresponding alcohol utilizing an appropriate reducing agent. Suitable amino protecting groups are well known in the art and include carbobenzoxy, t-butoxycarbonyl, and the like. A preferred amino protecting group is carbobenzoxy. A preferred N-protected chloroketone is N-benzyloxycarbonyl-L-phenylalanine chloromethyl ketone. A preferred reducing agent is sodium borohydride. The reduction reaction is conducted at a temperature of from xe2x88x9210xc2x0 C. to about 25xc2x0 C., preferably at about 0xc2x0 C., in a suitable solvent system such as, for example, tetrahydrofuran, and the like. Alternatively, the corresponding N-protected bromoketone can also be used and is especially useful for producing some chiral alcohols. The N-protected chloroketones are commercially available, e.g., such as from Bachem, Inc., Torrance, Calif. Alternatively, the chloroketones can be prepared by the procedure set forth in S. J. Fittkau, J. Prakt. Chem., 315, 1037 (1973), and subsequently N-protected utilizing procedures which are well known in the art.
The halo alcohol can be utilized directly, as described below, or, preferably, is then reacted, preferably at room temperature, with a suitable base in a suitable solvent system to produce an N-protected amino epoxide of the formula: 
wherein P and R2 are as defined above. Suitable solvent systems for preparing the amino epoxide include ethanol, methanol, isopropanol, tetrahydrofuran, dioxane, and the like including mixtures thereof. Suitable bases for producing the epoxide from the reduced chloroketone include potassium hydroxide, sodium hydroxide, potassium t-butoxide, DBU and the like. A preferred base is potassium hydroxide.
Alternatively, a protected amino epoxide can be prepared, such as in co-owned and co-pending PCT Patent Application Ser. No. PCT/US93/04804 which is incorporated herein by reference, starting with an L-amino acid which is reacted with a suitable amino-protecting group in a suitable solvent to produce an amino-protected L-amino acid ester of the formula: 
wherein P3 represents carboxyl-protecting group, e.g., methyl, ethyl, benzyl, tertiary-butyl and the like; R2 is as defined above; and P1 and P2 independently are selected from amine protecting groups, including but not limited to, arylalkyl, substituted arylalkyl, cycloalkenylalkyl and substituted cycloalkenylalkyl, allyl, substituted allyl, acyl, alkoxycarbonyl, aralkoxycarbonyl and silyl. Examples of arylalkyl include, but are not limited to benzyl, ortho-methylbenzyl, trityl and benzhydryl, which can be optionally substituted with halogen, alkyl of C1-C8, alkoxy, hydroxy, nitro, alkylene, amino, alkylamino, acylamino and acyl, or their salts, such as phosphonium and ammonium salts. Examples of aryl groups include phenyl, naphthalenyl, indanyl, anthracenyl, durenyl, 9-(9-phenylfluorenyl) and phenanthrenyl, cycloalkenylalkyl or substituted cycloalkylenylalkyl radicals containing cycloalkyls of C6-C10. Suitable acyl groups include carbobenzoxy, t-butoxycarbonyl, iso-butoxycarbonyl, benzoyl, substituted benzoyl, butyryl, acetyl, tri-fluoroacetyl, tri-chloroacetyl, phthaloyl and the like.
Additionally, the P1 and/or P2 protecting groups can form a heterocyclic ring with the nitrogen to which they are attached, for example, 1,2-bis(methylene)benzene, phthalimidyl, succinimidyl, maleimidyl and the like and where these heterocyclic groups can further include adjoining aryl and cycloalkyl rings. In addition, the heterocyclic groups can be mono-, di- or tri-substituted, e.g., nitrophthalimidyl. The term silyl refers to a silicon atom optionally substituted by one or more alkyl, aryl and aralkyl groups.
Suitable silyl protecting groups include, but are not limited to, trimethylsilyl, triethylsilyl, tri-isopropylsilyl, tert-butyldimethylsilyl, dimethylphenylsilyl, 1,2-bis(dimethylsilyl)benzene, 1,2-bis(dimethylsilyl)ethane and diphenylmethylsilyl. Silylation of the amine functions to provide mono- or bis-disilylamine can provide derivatives of the aminoalcohol, amino acid, amino acid esters and amino acid amide. In the case of amino acids, amino acid esters and amino acid amides, reduction of the carbonyl function provides the required mono- or bis-silyl aminoalcohol. Silylation of the aminoalcohol can lead to the N,N,O-tri-silyl derivative. Removal of the silyl function from the silyl ether function is readily accomplished by treatment with, for example, a metal hydroxide or ammonium flouride reagent, either as a discrete reaction step or in situ during the preparation of the amino aldehyde reagent. Suitable silylating agents are, for example, trimethylsilyl chloride, tert-buty-dimethylsilyl chloride, phenyldimethylsilyl chloride, diphenylmethylsilyl chloride or their combination products with imidazole or DMF. Methods for silylation of amines and removal of silyl protecting groups are well known to those skilled in the art. Methods of preparation of these amine derivatives from corresponding amino acids, amino acid amides or amino acid esters are also well known to those skilled in the art of organic chemistry including amino acid/amino acid ester or aminoalcohol chemistry.
Preferably P1 and P2 are independently selected from aralkyl and substituted aralkyl. More preferably, each of P1 and P2 is benzyl. As illustrated in the Examples below, P, P1 and P2 may serve as a nitrogen protecting group which is later removed in the preparation of compounds of this invention or may form a part of the final inhibitor structure. For example, benzoyl, benzyloxycarbonyl, t-butoxycarbonyl, pyridylmethoxycarbonyl, tetrahydrofuryloxycarbonyl, tetrahydrothiophene-S,S-dioxideoxycarbonyl, pyridylcarbonyl and the like can be used to both protect a nitrogen from undergoing an undesired reaction and also be part of the structure of an active enzyme inhibitor.
The amino-protected L-amino acid ester is then reduced, to the corresponding alcohol. For example, the amino-protected L-amino acid ester can be reduced with diisobutylaluminum hydride at xe2x88x9278xc2x0 C. in a suitable solvent such as toluene. Preferred reducing agents include lithium aluminium hydride, lithium borohydride, sodium borohydride, borane, lithium tri-ter-butoxyaluminum hydride, borane/THF complex. Most preferably, the reducing agent is diisobutylaluminum hydride (DiBAL-H) in toluene. The resulting alcohol is then converted, for example, by way of a Swern oxidation, to the corresponding aldehyde of the formula: 
wherein P1, P2 and R2 are as defined above. Thus, a dichloromethane solution of the alcohol is added to a cooled (xe2x88x9275 to xe2x88x9268xc2x0 C.) solution of oxalyl chloride in dichloromethane and DMSO in dichloromethane and stirred for 35 minutes.
Acceptable oxidizing reagents include, for example, sulfur trioxide-pyridine complex and DMSO, oxalyl chloride and DMSO, acetyl chloride or anhydride and DMSO, trifluoroacetyl chloride or anhydride and DMSO, methanesulfonyl chloride and DMSO or tetrahydro thiophene-S-oxide, toluenesulfonyl bromide and DMSO, trifluoromethanesulfonyl anhydride (triflic anhydride) and DMSO, phosphorus pentachloride and DMSO, dimethylphosphoryl chloride and DMSO and isobutyl chloroformate and DMSO. The oxidation conditions reported by Reetz et al [Angew Chem., 99, p. 1186, (1987)], Angew Chem. Int. Ed. Engl., 26, p. 1141, 1987) employed oxalyl chloride and DMSO at xe2x88x9278xc2x0 C.
The preferred oxidation method described in this invention is sulfur trioxide pyridine complex, triethylamine and DMSO at room temperature. This system provides excellent yields of the desired chiral protected amino aldehyde usable without the need for purification i.e., the need to purify kilograms of intermediates by chromatography is eliminated and large scale operations are made less hazardous. Reaction at room temperature also eliminated the need fo the use of low temperature reactor which makes the process more suitable for commercial production.
The reaction may be carried out under an inert atmosphere such as nitrogen or argon, or normal or dry air, under atmospheric pressure or in a sealed reaction vessel under positive pressure. Preferred is a nitrogen atmosphere. Alternative amine bases include, for example, tri-butyl amine, tri-isopropyl amine, N-methylpiperidine, N-methyl morpholine, azabicyclononane, diisopropylethylamine, 2,2,6,6-tetramethylpiperidine, N,N-dimethylaminopyridine, or mixtures of these bases. Triethylamine is a preferred base. Alternatives to pure DMSO as solvent include mixtures of DMSO with non-protic or halogenated solvents such as tetrahydrofuran, ethyl acetate, toluene, xylene, dichloromethane, ethylene dichloride and the like. Dipolar aprotic co-solvents include acetonitrile, dimethylformamide, dimethylacetamide, acetamide, tetramethyl urea and its cyclic analog, N-methylpyrrolidone, sulfolane and the like. Rather than N,N-dibenzylphenylalaninol as the aldehyde precursor, the phenylalaninol derivatives discussed above can be used to provide the corresponding N-monosubstituted [either P1 or P2xe2x95x90H] or N,N-disubstituted aldehyde.
In addition, hydride reduction of an amide or ester derivative of the corresponding alkyl, benzyl or cycloalkenyl nitrogen protected phenylalanine, substituted phenylalanine or cycloalkyl analog of phenyalanine derivative can be carried out to provide the aldehydes. Hydride transfer is an additional method of aldehyde synthesis under conditions where aldehyde condensations are avoided, cf, Oppenauer Oxidation.
The aldehydes of this process can also be prepared by methods of reducing protected phenylalanine and phenylalanine analogs or their amide or ester derivatives by, e.g., sodium amalgam with HCl in ethanol or lithium or sodium or potassium or calcium in ammonia. The reaction temperature may be from about xe2x88x9235xc2x0 C. to about 45xc2x0 C., and preferably from abut 5xc2x0 C. to about 25xc2x0 C. In the case of liquid amonia, the preferred temperature is about xe2x88x9233xc2x0 C. Two additional methods of obtaining the nitrogen protected aldehyde include oxidation of the corresponding alcohol with bleach in the presence of a catalytic amount of 2,2,6,6-tetramethyl-1-pyridyloxy free radical. In a second method, oxidation of the alcohol to the aldehyde is accomplished by a catalytic amount of tetrapropylammonium perruthenate in the presence of N-methylmorpholine-N-oxide.
Alternatively, an acid chloride derivative of a protected phenylalanine or phenylalanine derivative as disclosed above can be reduced with hydrogen and a catalyst such as Pd on barium carbonate or barium sulphate, with or without an additional catalyst moderating agent such as sulfur or a thiol (Rosenmund Reduction).
The aldehyde resulting from the Swern oxidation is then reacted with a halomethyllithium reagent, which reagent is generated in situ by reacting an alkyllithium or arylithium compound with a dihalomethane represented by the formula X1CH2X2 wherein X1 and X2 independently represent I, Br or Cl. For example, a solution of the aldehyde and chloroiodomethane in THF is cooled to xe2x88x9278xc2x0 C. and a solution of n-butyllithium in hexane is added. The resulting product is a mixture of diastereomers of the corresponding amino-protected epoxides of the formulas: 
The diastereomers can be separated e.g., by chromatography, or, alternatively, once reacted in subsequent steps the diastereomeric products can be separated. For compounds having the (S) stereochemistry, a D-amino acid can be utilized in place of the L-amino acid.
The addition of chloromethylithium or bromomethylithium to a chiral amino aldehyde is highly diastereoselective. Preferably, the chloromethyllithium or bromomethylithium is generated in-situ from the reaction of the dihalomethane and n-butyllithium. Acceptable methyleneating halomethanes include chloroiodomethane, bromochloromethane, dibromomethane, diiodomethane, bromofluoromethane and the like. The sulfonate ester of the addition product of, for example, hydrogen bromide to formaldehyde is also a methyleneating agent. Tetrahydrofuran is the preferred solvent, however alternative solvents such as toluene, dimethoxyethane, ethylene dichloride, methylene chloride can be used as pure solvents or as a mixture. Dipolar aprotic solvents such as acetonitrile, DMF, N-methylpyrrolidone are useful as solvents or as part of a solvent mixture. The reaction can be carried out under an inert atmosphere such as nitrogen or argon. For n-butyl lithium can be substituted other organometalic reagents reagents such as methyllithium, tert-butyl lithium, sec-butyl lithium, phenyllithium, phenyl sodium and the like. The reaction can be carried out at temperatures of between about xe2x88x9280xc2x0 C. to 0xc2x0 C. but preferably between about xe2x88x9280xc2x0 C. to xe2x88x9220xc2x0 C. The most preferred reaction temperatures are between xe2x88x9240xc2x0 C. to xe2x88x9215xc2x0 C. Reagents can be added singly but multiple additions are preferred in certain conditions. The preferred pressure of the reaction is atmospheric however a positive pressure is valuable under certain conditions such as a high humidity environment.
Alternative methods of conversion to the epoxides of this invention include substitution of other charged methylenation precurser species followed by their treatment with base to form the analogous anion. Examples of these species include trimethylsulfoxonium tosylate or triflate, tetramethylammonium halide, methyldiphenylsulfoxonium halide wherein halide is chloride, bromide or iodide.
The conversion of the aldehydes of this invention into their epoxide derivative can also be carried out in multiple steps. For example, the addition of the anion of thioanisole prepared from, for example, a butyl or aryl lithium reagent, to the protected aminoaldehyde, oxidation of the resulting protected aminosulfide alcohol with well known oxidizing agents such as hydrogen peroxide, tert-butyl hypochlorite, bleach or sodium periodate to give a sulfoxide. Alkylation of the sulfoxide with, for example, methyl iodide or bromide, methyl tosylate, methyl mesylate, methyl triflate, ethyl bromide, isopropyl bromide, benzyl chloride or the like, in the presence of an organic or inorganic base Alternatively, the protected aminosulfide alcohol can be alkylated with, for example, the alkylating agents above, to provide a sulfonium salts that are subsequently converted into the subject epoxides with tert-amine or mineral bases.
The desired epoxides formed, using most preferred conditions, diastereoselectively in ratio amounts of at least about an 85:15 ratio (S:R). The product can be purified by chromatography to give the diastereomerically and enantiomerically pure product but it is more conveniently used directly without purification to prepare retroviral protease inhibitors. The foregoing process is applicable to mixtures of optical isomers as well as resolved compounds. If a particular optical isomer is desired, it can be selected by the choice of starting material, e.g., L-phenylalanine, D-phenylalanine, L-phenylalaninol, D-phenylalaninol, D-hexahydrophenylalaninol and the like, or resolution can occur at intermediate or final steps. Chiral auxiliaries such as one or two equivilants of camphor sulfonic acid, citric acid, camphoric acid, 2-methoxyphenylacetic acid and the like can be used to form salts, esters or amides of the compounds of this invention. These compounds or derivatives can be crystallized or separated chromatographically using either a chiral or achiral column as is well known to those skilled in the art.
The amino epoxide is then reacted, in a suitable solvent system, with an equal amount, or preferably an excess of, a desired amine of the formula R3NH2, wherein R3 is hydrogen or is as defined above. The reaction can be conducted over a wide range of temperatures, e.g., from about 10xc2x0 C. to about 100xc2x0 C., but is preferably, but not necessarily, conducted at a temperature at which the solvent begins to reflux. Suitable solvent systems include protic, non-protic and dipolar aprotic organic solvents such as, for example, those wherein the solvent is an alcohol, such as methanol, ethanol, isopropanol, and the like, ethers such as tetrahydrofuran, dioxane and the like, and toluene, N,N-dimethylformamide, dimethyl sulfoxide, and mixtures thereof. A preferred solvent is isopropanol. Exemplary amines corresponding to the formula R3NH2 include benzyl amine, isobutylamine, n-butyl amine, isopentyl amine, isoamylamine, cyclohexanemethyl amine, naphthylene methyl amine and the like. The resulting product is a 3-(N-protected amino)-3-(R2)-1-(NHR3)-propan-2-ol derivative (hereinafter referred to as an amino alcohol) can be represented by the formulas: 
wherein P, P1, P2, R2 and R3 are as described above. Alternatively, a haloalcohol can be utilized in place of the amino epoxide.
The amino alcohol defined above is then reacted in a suitable solvent with a sulfonyl chloride (R4SO2Cl) or sulfonyl anhydride in the presence of an acid scavenger. Suitable solvents in which the reaction can be conducted include methylene chloride, tetrahydrofuran. Suitable acid scavengers include triethylamine, pyridine. Preferred sulfonyl chlorides are methanesulfonyl chloride and benzenesulfonyl chloride. The resulting sulfonamide derivative can be represented, depending on the epoxide utilized by the formulas 
wherein P, P1, P2, R2, R3 and R4 are as defined above. These inter mediates are useful for preparing inhibitor compounds of the present invention and are also active inhibitors of retroviral proteases.
The sulfonyl halides of the formula R4SO2X can be prepared by the reaction of a suitable Grignard or alkyl lithium reagent with sulfuryl chloride, or sulfur dioxide followed by oxidation with a halogen, preferably chlorine. Also, thiols may be oxidized to sulfonyl chlorides using chlorine in the presence of water under carefully controlled conditions. Additionally, sulfonic acids may be converted to sulfonyl halides using reagents such as PCl5, and also to anhydrides using suitable dehydrating reagents. The sulfonic acids may in turn be prepared using procedures well known in the art. Such sulfonic acids are also commercially available. In place of the sulfonyl halides, sulfinyl halides (R4SOX) or sulfenyl halides (R4SX) can be utilized to prepare compounds wherein the xe2x80x94SO2xe2x80x94 moiety is replaced by an xe2x80x94SOxe2x80x94 or xe2x80x94Sxe2x80x94 moiety, respectively.
Alternatively, the sulfonyl halides of the formula R4SO2X can be prepared by well known procedures for chlorosulformation of an aromatic compound, for example, reaction with chlorosulfonic acid or sulfur trioxide/N,N-dimethylfomamide complex under suitable reaction conditions. See Wolf et al, Z. Chem. 7:20, 1967, 8:111, 1968; Culbertson et al, J. Chem. Soc., p. 992 (1968) and EP 254577.
Following preparation of the sulfonamide derivative, the amino protecting group P or P1 and P2 amino protecting groups are removed under conditions which will not affect the remaining portion of the molecule. These methods are well known in the art and include acid hydrolysis, hydrogenolysis and the like. A preferred method involves removal of the protecting group, e.g., removal of a carbobenzoxy group, by hydrogenolysis utilizing palladium on carbon in a suitable solvent system such as an alcohol, acetic acid, and the like or mixtures thereof. Where the protecting group is a t-butoxycarbonyl group, it can be removed utilizing an inorganic or organic acid, e.g., HCl or trifluoroacetic acid, in a suitable solvent system, e.g., dioxane or methylene chloride. The resulting product is the amine salt derivative. Following neutralization of the salt, the amine is then reacted with an carboxylic acid, thiocarboxylic acid or corresponding derivative thereof represented by the formula 
wherein t, R1, R7, R8, R10 and R11 are as defined above, to produce the antiviral compounds of the present invention having the formula: 
wherein t, R1, R2, R3, R4, R6, R7, R8, R10 and R11 are as defined above. Preferred protecting groups in this instance are a benzyloxycarbonyl group or a t-butoxycarbonyl group.
Alternatively, the coupling order may be reversed as shown in Scheme III. The protected amino alcohol from the epoxide opening can be further protected at the newly introduced amino group with a protecting group Pxe2x80x2 which is not removed when the first protecting P is removed. One skilled in the art can choose appropriate combinations of P and Pxe2x80x2. One suitable choice is when P is Cbz and Pxe2x80x2 is Boc. The resulting compound represented by the formulas 
can be carried through the remainder of the synthesis to provide a compound of the formula 
and the new protecting group Pxe2x80x2 is selectively removed, and following deprotection, the resulting amine reacted to form the sulfonamide derivative as described above. This selective deprotection and conversion to the sulfonamide can be accomplished at either the end of the synthesis or at any appropriate intermediate step if desired.
Protected S-acetylthioalkylcarboxylic acids can be utilized to prepare the sulfonamidealkylcarboxylic acids starting material of this invention. The protected S-acetylthioalkylcarboxylic acids can be oxidized in the presence of chlorine to form the corresponding sulfonyl chloride compounds. The sulfonyl chloride can then be reacted in the presence of a proton scavenger with R10R11NH to produce the corresponding protected aminosulfonylalkylcarboxylic acids. After deprotection, the carboxylic acids can be utilized to prepare the compounds of this invention. Reactive groups, such as alcohols, thiols, primary amines, secondary amines and the like, which are present on groups R1, R7, R10 and R11 should be protected and deprotected as needed. The overall reaction sequence can be shown as follows 
wherein R1, R7, R8, R10, R11 and P3 are as defined above. This process can also be used in the asymmetric synthesis of starting materials having asymmetric centers.
The protected S-acetylthioalkylcarboxylic acids can be readily prepared using standard procedures from the corresponding substituted S-acetylthioalkylcarboxylic acids 
or can be readily prepared by acetylating the corresponding substituted thiols 
with acetic anhydride, acetyl chloride or the like using standard conditions. Such substituted thiols can be readily prepared from commercially available starting materials using standard procedures and reagents well known in the art. For example, a carbonyl can be readily converted into a thiocarbonyl which can be reduced to a thiol or reacted with a nucleophile to form a substituted thiol. Alternatively, a carboxylic acid or ester having a leaving group, such as chlorine atom, bromine atom, tosylate, mesylate and the like, can be reacted with sulfide anion, benzylthiol followed by debenzylation, thiocyanide anion followed by decyanation, and the like, to form the thiol, or with thioacetate anion to form the acetylthio derivative. In addition, Michael addition of sulfide anion on this acetate to a double bond containing carboxylic acid or protected carboxylic acid can provide the desired thioalkyl carboxylic acid. Substituted thioalkylcarboxylic acids having chiral centers can be prepared from sugars using standard synthetic methods, or by resolution of the carboxylic acids using resolving reagents or resolving chromatographic columns.
The thiocarbonyl compounds of this invention are really prepared by methods well known to those skilled in the art, for example, by treatment of a carbonyl compound with Lawesson""s reagent (2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide) which is an article of commerce. Phosphorus pentasulfide may also be used or one can treat an amine of this invention with a pre-formed thiocarbonyl reagent such as thiocarbonylchloride in the presence of base.
In place of the sulfonyl halides, sulfinyl halides (RSOCl) and sulfenyl halides (RSCl) can be utilized to prepare compounds wherein the xe2x80x94SO2xe2x80x94 moiey is replaced by xe2x80x94SOxe2x80x94 or xe2x80x94Sxe2x80x94, respectively.
It is contemplated that for preparing compounds of the Formulas having R6, the compounds can be prepared following the procedures set forth above and, prior to coupling the sulfonamide-carboxylic acid derivative 
to the protected amine or sulfonamide amine 
by alkylation or reductive amination. For example, the amino group can be alkylated with sodium cyanoborohydride and an appropriate aldehyde or ketone at room temperature. It is also contemplated that where R3 of the amino alcohol intermediate is hydrogen, the inhibitor compounds of the present invention wherein R3 is alkyl, or other substituents wherein the xcex1-C contains at least one hydrogen, can be prepared through reductive amination of the final product of the reaction between the amino alcohol and the amine or at any other stage of the synthesis for preparing the inhibitor compounds.
Contemplated equivalents of the general formulas set forth above for the antiviral compounds and derivatives as well as the intermediates are compounds otherwise corresponding thereto and having the same general properties, such as tautomers thereof as well as compounds, wherein one or more of the various R groups are simple variations of the substituents as defined therein, e.g., wherein R is a higher alkyl group than that indicated. In addition, where a substituent is designated as, or can be, a hydrogen, the exact chemical nature of a substituent which is other than hydrogen at that position, e.g., a hydrocarbyl radical or a halogen, hydroxy, amino and the like functional group, is not critical so long as it does not adversely affect the overall activity and/or synthesis procedure.
The chemical reactions described above are generally disclosed in terms of their broadest application to the preparation of the compounds of this invention. Occasionally, the reactions may not be applicable as described to each compound included within the disclosed scope. The compounds for which this occurs will be readily recognized by those skilled in the art. In all such cases, either the reactions can be successfully performed by conventional modifications known to those skilled in the art, e.g., by appropriate protection of interfering groups, by changing to alternative conventional reagents, by routine modification of reaction conditions, and the like, or other reactions disclosed herein or otherwise conventional, will be applicable to the preparation of the corresponding compounds of this invention. In all preparative methods, all starting materials are known or readily preparable from known starting materials.
Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
All reagents were used as received without purification. All proton and carbon NMR spectra were obtained on either a Varian VXR-300 or VXR-400 nuclear magnetic resonance spectrometer.