Efficient large scale preparation of neutral endopeptidase/angiotensin-converting enzyme dual inhibitor CGS30440

The development and piloting of a potential manufacturing process for ACE/NEP dual inhibitor CGS30440 is described. The synthesis proceeds sequentially from 1-aminocyclopentanecarboxylic acid via N-protection, peptide coupling with L-tyrosine ethyl ester, O-methylation of N-protected [(1-amino-1-cyclopentyl)carbonyl]-L-tyrosine ethyl ester, N-deprotection, peptide coupling of [(1-amino-1-cyclopentyl)carbonyl]-O-methyl-L-tyrosine ethyl ester with D-2-bromo-3methylbutyric acid, and final displacement of bromide with thioacetate. This approach is superior to shorter Discovery routes based upon final peptide coupling of L-2-(acetylthio)-3-methylbutanoic acid to [(1-amino-1-cyclopentyl)carbonyl]-O-methyl-L-tyrosine ethyl ester.