Copper(I)-Promoted Condensation of α-Amino Acids with β-Keto Thio Esters: Synthesis of N-Acylated L-Leucine Derivatives Containing (S)-4-Hydroxy-5-methyl- and (S)-4-Hydroxy-2,5-dimethyl-3-oxohexanoic Acid

Article abstract of DOI:10.1021/jo00229a019

Acylation of lithium enolates of ethyl acetate and ethyl thioacetate with derivatives of (S)-2-hydroxy-3-methylbutanoic acid, activated at the carboxyl function as the acid chloride, unsymmetrical carbonic anhydride, or active ester, furnished the corresp