Photodecarboxylative C–H Alkylation of Azauracils with <i>N</i>-(Acyloxy)phthalimides

Abstract

We disclose a transition-metal-free NaI/PPh₃-mediated direct C-H alkylation of azauracils using <i>N</i>-(acyloxy)pthalimides (NHPIs) as readily available alkyl surrogates under visible light irradiation. Detailed mechanistic studies reveal formation of a photoactivated electron donor-acceptor (EDA) complex between NaI/PPh₃, TMEDA, and alkyl NHPI ester and establish the crucial role of TMEDA in increasing the activity of the photoredox system. The reaction demonstrates a broad scope, scalability, and appreciable functional group tolerance. A variety of azauracils are shown to undergo alkylation by primary, secondary, and tertiary NHPI esters under mild conditions, furnishing the desired products in good to excellent yields.