C(sp3)-C(sp3) Radical-Cross-Coupling Reaction via Photoexcitation

Org Lett. 2023 Nov 24;25(46):8246-8251. doi: 10.1021/acs.orglett.3c03276. Epub 2023 Nov 10.

Abstract

The photoexcitation of 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) in the presence of a base triggers the single-electron-transfer-mediated desulfonative radical-cross-coupling (RCC) reaction without the need for any metal or photocatalyst. 4-Alkyl-substituted 1,4-DHPs as the electron donor (reductant) and alkyl sulfones as the electron acceptor (oxidant) are chosen strategically as the two best-matched modular radical precursors for the construction of C(sp3)-C(sp3) bonds. Ultraviolet light-emitting diodes (365 nm) have proven to be adequate for inducing single-electron transfer between two radical precursors in the excited state. Following this designed strategy, a diverse collection of primary, secondary, and tertiary persistent alkyl radicals from both radical precursors have been used to forge C(sp3)-C(sp3) bonds. This blueprint features good functional group compatibility, a broad scope, and detailed mechanistic investigation.