Acid-catalyzed O-allylation of β-hydroxy-α-amino acids: an entry into conformationally constrained dipeptide surrogates

Abstract O-Allylation using allyl trichloroimidate 5 was found to be an effective method for the introduction of an acetaldehyde equivalent onto the hydroxyl group of β-hydroxy-α-amino acid derivatives. Rigid oxygen containing tricyclic anti-phenylalanylleucine mimic 1 was efficiently synthesized using this method. This mimetic was further elaborated to provide 7c , a potent inhibitor of angiotensin-1 converting enzyme (ACE).