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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