Organocatalyzed trifunctionalization of alkynyl 1,2-diones for the concise synthesis of acyloxy allylidene malonates and γ-alkylidenebutenolides

Two types of unprecedented organic phosphine-catalyzed trifunctionalization of ynones have been achieved under mild and environmentally benign conditions using iPrOH as the solvent, delivering a range of synthetically valuable acyloxy allylidene malonates and γ-alkylidenebutenolides in good yields with high stereoselectivities. A series of uncommon bond cleavage and bond formation processes have been observed in the reactions, showing the robustness of organocatalysis in facilitating complicated transformations. Mechanistic studies indicate that iPrOH plays a dual role as both the solvent and the reactant.