Stereospecific Synthesis of β³‐Amino Acid Derivatives from Propargylic Alcohols: Efficient Solution‐Phase Synthesis of Oligopeptides without Coupling Agents

A stereospecific synthesis of beta(3)-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 functionality of an amino acid derivative. Through this strategy a chain elongation at the N-terminus has been effected. The N-deprotection and repetition of the homologation with other Se-phenyl selenocarboxylate intermediates produced beta- and mixed alpha/beta-oligopeptides without the use of coupling agents.