Simple synthesis of stable phosphorus ylides derived from imidazolidine-2-thione. Efficient one-pot synthesis of α-amino esters with β-phosphorus substituents

Abstract

Crystalline phosphorus ylides are obtained in nearly quantitative yields from the addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and imidazolidine-2-thione. A dynamic NMR effect is observed in the 1H NMR spectrum of the stabilized ylide obtained from dimethyl acetylenedicarboxylate (ΔG≠ = 66.6 kJmol -1) and is attributed to restricted rotation around the carbon-carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group. Copyright © Taylor & Francis Inc.