sources e g tetraalkylammonium halides such as tetramethyl ammonium chloride may be equally efficacious inert solvents which may be employed include hexane dimethylformamide dimethylacetamide and like solvents which are capable of maintaining substantially all of the reagents and reactants in solution examples of tin transfer reagents include tetramethylstannane tetraethylstannane tri n butyl vinyl stannane tri n butyl allyl stannane tri n butyl methoxymethyl stannane tri n butyl ethynyl stannane tri n butyl z 1 propene 1 yl stannane tri n butyl z 3 3 3 trifluoro 1 propene 1 ylstannane tri n butyl benzyloxymethyl stannane tri n butyl 2 propyne 1 yl stannane and the like the above process is carried out at a temperature from about 70 u00b0 c to about 150 u00b0 c preferably from about 25 u00b0 c to about 75 u00b0 c under substantially anhydrous conditions and preferably in an inert atmosphere such as a nitrogen or argon atmosphere the 34 tin transfer reagent 34 of the formula tri c 1 c 6 alkyl sn r 2 or sn r 2 4 is chosen by virtue of the desired r 2 substituent 3 position in the u03b2 lactam compound as to the c 1 c 6 alkyl groups which may appear on the tin transfer reagent n butyl is preferred i e tri n butyl tin r 2 is the preferred reagent further in some cases it will be preferable to use a.