Synthesis of chiral diamines using novel 2-trichloromethyloxazolidin-4-one precursors derived from 5-oxo-proline and proline

Efficient syntheses of chiral vicinal diamines derived from (S)-oxo-proline and (S)-proline are described. The novel diastereomerically pure precursor (2R,5S)-2-trichloromethyl-1-aza-3-oxabicyclo-[3.3.0]-octan-4,8-dione 3 and its enantiomer are readily available by reaction of the inexpensive enantiomers of 5-oxo-proline with chloral. Compound 3 reacts with primary and secondary amines to afford the 5-oxo-prolylamides 4 in quantitative yield. In contrast, the (S)-proline-derived precursor (2R,5S)-2-trichloromethyl-1-aza-3-oxabicyclo[3.3.0]octan-4-one 6 gave (S)-N-formylprolylamides 9 and/or (S)-prolylamides 8 depending on the reaction conditions. Upon reduction with LiAlH4, amides 4 and 9 afforded the proline-derived (S)-2-(alkylaminomethyl)pyrrolidines 1 and (S)-N- methyl-2-(alkylaminomethyl)-pyrrolidines 5 in 70-90% yields. (C) 2002 Elsevier Science Ltd. All rights reserved.