α-Amino Acids as Chiral Educts for Asymmetric Products. The Synthesis of α'-Amino-α,β-ynones

Article abstract of DOI:10.1021/jo00221a004

α-Amino acid isoxazolidides have been developed as educts for the preparation of optically pure α'-amino-α,β-ynones.The α-amino acids were first N-protected as their ethoxycarbonyl, tert-butoxycarbonyl, or phenylsulfonyl derivatives.The isoxazolidides then were formed by the simple, high yield acylation of isoxazolidine by in situ generated α-amino acid isobutyl carbonic anhydrides.Individual isoxazolidides of L-α-N-substituted alanine, phenylalanine, and methionine, when treated with lithium acetylide, lithium (trimethylsilyl)acetylide, or 1-hexynyllithium, gave high yields of the corresponding optically pure α,β-acetylenic ketones.