Diversified Reactivity of Triphenylphosphine: Reinvestigation of the Phosphine-Mediated Reductive Condensation Approach for the Synthesis of Substituted Furans

A reinvestigation of "Phosphine-Mediated Reductive Condensation of γ-Acyloxy Butynoates: A Diversity Oriented Strategy for the Construction of Substituted Furans" (J. Am. Chem. Soc. 2004, 126, 4118–4119) revealed different chemoselectivity of triphenylphosphine in the reactions with the γ-acyloxy butynoate substrates of varying substitution patterns/electronics. Furthermore, the electronics of the triaryl phosphine reagent could be tuned to trap a putative intermediate such as A, leading to the semihydrogenation of propiolamide substrates.