C(sp3)─S Bond Formation via the Synergy of Oxidative With Reductive Photocatalysts Through Photoredox and Dual Hydrogen Atom Transfer Processes.

Abstract

A primary objective of organic synthesis is to establish a catalytic methodology that is mild, straightforward, and economically efficient. Thioesters are widely employed in the realms of physiology, pharmacology, and agriculture. It is imperative to continuously expand the range of sulfur-containing precursors to keep pace with the cutting-edge advancements in the field of organic sulfur chemistry. This research has uncovered that polysulfide anions (K₂S_x), which serve as reducing catalysts, can also effectively act as sulfur reagents, providing the formation of C(sp³)-S bonds through a photoredox catalysis with an oxidative photocatalyst tetrabutylammonium decatungstate (TBADT) and dual hydrogen atom transfer (DHAT) process. In a pioneering study, a combinatorial strategy of an oxidative photocatalyst TBADT is presented with a reductive photocatalyst K₂S_x, enabled a photo-induced three-component coupling reaction of simple aldehydes with alkanes containing C(sp³)─H and polysulfide anions. A numbers of thioester derivatives are successfully obtained in good yields, while a by-product H₂S is captured and identified by gas chromatography analysis. Concurrently, density functional theory (DFT) calculations provided the theoretical support of the reaction mechanism.