Base‐Mediated Tandem 1,6‐Conjugate Addition/Cyclization Enabling the Synthesis of 4,5‐Disubstituted 3(2 H )‐Furanones From Haloacetoacetates and p ‐Quinone Methides

Abstract

A transition‐metal‐free tandem 1,6‐conjugate addition/cyclization of haloacetoacetates with p ‐quinone methides has been developed as an efficient strategy for the synthesis of structurally diverse 4,5‐disubstituted 3(2H)‐furanones. The reaction proceeds under mild base‐mediated conditions, delivering the desired products in good to excellent yields (up to 94%) within short reaction times. The protocol exhibits broad substrate tolerance, accommodating electronically varied p ‐quinone methides, polycyclic and heteroaryl systems, and isatin‐derived analogues, thereby enabling the construction of quaternary carbon centers. Notably, when isatylidene malonitriles are employed, the reaction pathway diverges to afford spiro[indoline–pyran] frameworks with high efficiency. Operational simplicity, metal‐free conditions, and scalability highlight the synthetic utility of this methodology for accessing biologically relevant oxygen‐containing heterocycles.