An acyl-iminium ion cyclization route to a novel conformationally restricted dipeptide mimic: applications to angiotensin-converting enzyme inhibition

GA Flynn, EL Giroux, RC Dage

Index: Flynn, Gary A.; Giroux, Eugene L.; Dage, Richard C. Journal of the American Chemical Society, 1987 , vol. 109, # 25 p. 7914 - 7915

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Citation Number: 117

Abstract

reflux, 3 h) gave a 1: l ratio of isomeric acylenamines 6a and 6b which were separated by preparative HPLC (50% EtOAc/hexane) in 70% overall yield. Cyclization of acylenamine 6a (CF3S03H, CH2C1,, 25 OC, 24 h) and re-esterification of the acidic product (Ph2CN2, CH2C1,) gave the desired optically pure benzhydryl ester 7 (mp 156-157 OC,[aIDZo=-88.1, 1.1, CHC1,) in 77% yield. The relative stereochemistry and conformation of 7 have been ...