
{"publication_number": "US-2008058551-A1", "abstract": "a method of making high diastereoselective and enantiomerically pure pseudonorephedrine and the hitherto unknown compound pseudonorephedrine .", "application_number": "US-83651007-A", "description": "while the description below focuses on the formation of ( 1s , 2s )- pseudonorephedrine as illustrated by the reactions of fig1 - 3 , ( 1r , 2r )- pseudonorephedrine may be prepared by the identical process using ( 1s , 2r )- norephedrine as the starting material ( fig4 - 6 ). thus , as illustrated in fig1 , the conversion of ( 1r , 2s ) norephedrine 1a is achieved by acylation with di - tert - butyl dicarbonate and triethylamine to afford the protected secondary carbamate derivative 3a . upon the exposure of 3a to additional triethylamine and methanesulfonyl chloride , the oxazolidinones 5a , 6a , are formed , inducing the desired inversion on the phenyl substituent leading to the target oxazolidinone 5a . an appropriate substitute for methanesulfonyl chloride may be used provided that , like methanesulfonyl chloride , acylation of the amine occurs as well as displacement of the alcohol , as discussed below . it is believed that the formation of the oxazolidinone is accomplished through the formation of a mesylated intermediate 4a , although this compound was not isolated nor was it observed in the crude product . the invention is not intended to be limited to a reaction forming such an intermediate . b hplc data was gathered on a shimadzu scl - 10 avp system ( d . r . are reported as anti : syn ); c crude d . r . determined by hplc on a dynamax - 100 { acute over ( \u00e5 )