Transition-Metal-Free, Visible-Light-Promoted C-S Cross-Coupling through Intermolecular Charge Transfer

Abstract

C-S cross-couplings are an important class of reactions applied across organic synthesis, materials science, and pharma-ceuticals. Several different methodologies have been developed to achieve this significant transformation. However, currently available synthetic procedures significantly rely on transition metals. This article describes historical developments in the field of transition-metal-catalyzed C-S cross-coupling reactions, the development of a visible-light-driven and catalyst-free approach to C-S bond formation, and future outlooks.

Keywords: C–S cross-coupling; charge transfer; electron donor–acceptor complex; late-stage functionalization; photochemistry; transition-metal-free.

Figure 1

Selected examples of sulfur-containing drugs and biologically active compounds

Scheme 1

Transition-metal-catalyzed C–S cross-coupling reactions

Scheme 2

Light-driven C–S cross-coupling reactions

Scheme 3

Scope of aryl bromides and iodides

Scheme 4

Scope of aryl chlorides and late-stage thiolation of pharmaceuticals

Scheme 5

Scope of (het)arenes

Scheme 6

Scope of thiols