Photodecarboxylative Radical Cascade Involving -(Acyloxy)phthalimides for the Synthesis of Pyrazolones.

We disclose '-arylidene--acryloyltosylhydrazides as novel skeletons for the synthesis of biologically relevant alkylated pyrazolones through a photoinduced radical cascade with -(acyloxy)pthalimides as readily available alkyl surrogates. The reaction proceeds through the formation of a photoactivated electron donor-acceptor (EDA) complex between alkyl -(acyloxy)phthalimide (NHPI) esters and LiI/PPh as a commercially available donor system. The reaction exhibits a broad scope and scalability, thereby enabling synthesis of a broad spectrum of functionally orchestrated alkylated pyrazolones under mild and transition-metal-free conditions.