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5-(Hydroxymethyl)-2-pyrrolidmone (3), prepared from L-pyroglutamic acid, was condensed with benzaldehyde to obtain the 0,iV-acetal 4 in excellent yield. Alkylation of 4 with 3-bromocyclohexene followed by reduction gave ímras-4-cyclohexyl-L-prolmol (7) in good chemical yield with excellent stereoselectivity. Sequential N-protection, oxidation of the alcohol to the acid, and N-deprotection furnished trons-4-cyclohexyl-L-proline (1) in excellent yield and quality. Compound 1 serves as an intermediate for the preparation of ACE inhibitors including Fosenopril.

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Development of an efficient and scalable process for the human immunodeficiency virus (HIV) protease inhibitor BMS-232632 1-[4-(pyridin-2-yl)phenyl]-5(S)-2,5-bis{[N-(methoxycarbonyl)-L-tert-leucinyl]-amino}-4(S)-hydroxy-6-phenyl-2-azahexane, is described. The key step in the synthesis of the intermediate N-1-(tert-butyloxycarbonyl)-N-2-[4-(pyridin-2-yl)benzylidene]hydrazone (11) was the Pd-mediated coupling of boronic acid 9 with 2-bromopyridine. An efficient procedure was developed for the chemoselective reduction of hydrazone 11 to hydrazine carbamate 4 (6) was prepared stereoselectively from chiral diol 10. The subsequent union of 4 and 6 followed by coupling with N-methoxycarbonyl-L-tert-leucine provided the free base BMS-232632 in high yield. Evaluation of a variety of salts and identification of bisulfate salt 19 with enhanced bioavailability are also described. . The key intermediate N-(tert-butyloxycarbonyl)-2(S)-amino-1-phenyl-3(R)-3,4-epoxy-butane

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