Stereoselective synthesis of dehydroamino acids using malonic acid half oxyester and aromatic aldehydes

摘要

An efficient and direct approach was developed for the synthesis of alpha,beta-dehydroamino acid derivatives with a broad range of substrates. Amido-substituted Malonic Acid Half Oxyesters (MAHOs) have proven to be excellent partners of various aromatic aldehydes in the presence of secondary amine, trifluoromethanesulfonic acid to perform a Knoevenagel-Doebner condensation under mild conditions with good to excellent yields. A mechanistic study revealed that the sequence involved the formation of an iminium intermediate to provide stereoselectively Z-alpha,beta-unsaturated amino acids. (C) 2016 Elsevier Ltd. All rights reserved.