Stereospecific Synthesis of β<sup>3</sup>-Amino Acid Derivatives from Propargylic Alcohols: Efficient Solution-Phase Synthesis of Oligopeptides without Coupling Agents
A stereospecific synthesis of β3‐amino acids has been accomplished starting from readily available and enantioenriched propargylic alcohols. This conversion can be effected in only three steps by selenium‐mediated organic transformations of the carbon–carbon triple bond. This method is especially attractive because the reactive Se‐phenyl selenocarboxylate intermediates can be trapped with the amine
A method for the synthesis of beta(3)-amino acids starting from alpha-amino acids is described. This conversion can be effected by an eight-step procedure which involves the transformation of the carboxylic group into an alkyne followed by a selenium-mediated conversion of the carbon-carbon triple bond to a Se-phenyl selenocarboxylate intermediate. The reactive Se-phenyl selenocarboxylate intermediates can be trapped with water, alcohols or the amine of an amino acid derivative to give beta(3)-amino acids, beta(3)-amino esters or mixed peptides, respectively. The whole transformations of the carboxylic group into an alkyne and of the alkyne group into beta(3)-amino acids may not require purification of the intermediate products but a workup and isolation procedure of crude materials. (C) 2010 Elsevier Ltd. All rights reserved.