Synthesis and Angiotensin Converting Enzyme‐Inhibitory Activity of N‐(( 1S)‐1‐Carboxy‐5‐(4‐piperidyl)pentyl)‐L‐alanine Derivatives.

As part of a search for potent and long-lasting angiotensin converting enzyme (ACE) inhibitors, various types of N-[(1S)-1-carboxy-5-(4-piperidyl)pentyl]-L-alanine derivatives (7a, 8-11) were prepared. The key synthetic intermediate, N-[(1S)-5-(1-benzyloxycarbonyl-4-piperidyl)-1-ethoxycarbonylpentyl]-L-alanine (17a), was synthesized by asymmetric reduction of the α-oxoester (13) with Lactobacillus paracasei subsp. paracasei followed by a substitution reaction with tert-butyl L-alaninate (15) and subsequent treatment with hydrogen chloride. Compounds 7a and 8-11 showed potent and long-lasting ACE-inhibitory activity in rats.