DBU-Catalyzed Aerobic CDC Reaction of Thiophenols

Abstract

A convenient method was developed for the preparation of thiolated compounds via a DBU-catalyzed aerobic cross-dehydrogenative coupling (CDC) reaction. The established protocol is environmentally friendly and operationally simple. Substrates like (hetero)aryl acetates, (hetero)aryl ketones, and indoles could be transformed into the corresponding thiolated products in moderate to high yields and further applied in the preparation of bioactive compounds in a prefunctionalization-free manner.

Organo‐Catalyzed Intermolecular Dehydrative Coupling Reaction to Prepare Arylacetic Acid Derivatives

“…[16] Besides, regarding the thioarylacetic acid preparation, the primary starting materials utilized for the construction of CÀ S bonds involving thiophenols are α-haloaryl compounds, aryldiazo compounds, [17] and aerobic cross-dehydrogenation coupling reactions. [18] Despite these significant achievements, they often rely on the use of specific catalysts, the inclusion of ligands, and the requirement for aromatics with activated substituents can limit their applicability and sustainability. From a sustainable standpoint, the development of atom efficient methods for conducting dehydrative coupling and SÀ H insertion reactions under mild conditions would be highly valuable.…”

“…On the other hand, the para ‐selective functionalization of phenols remains underdeveloped but highly demanding [16] . Besides, regarding the thioarylacetic acid preparation, the primary starting materials utilized for the construction of C−S bonds involving thiophenols are α ‐haloaryl compounds, aryldiazo compounds, [17] and aerobic cross‐dehydrogenation coupling reactions [18] . Despite these significant achievements, they often rely on the use of specific catalysts, the inclusion of ligands, and the requirement for aromatics with activated substituents can limit their applicability and sustainability.…”

A Thiol-Free Route to Alkyl Aryl Thioethers

“…More recently, some alternative metal-free approaches toward alkyl aryl thioethers have been developed. Among them are an N -chlorosuccinimide-promoted cross-coupling reaction of alkyl thiols with aryl Grignard reagents, an EDA-based visible light-mediated decarboxylative alkylation of thiophenols with N -hydroxy phthalimide esters as alkyl radical precursors, an arylation of alkyl thiols with diaryliodonium salts, an aryl halide-promoted visible light-induced C(sp 3 )–H bond thiolation with thiophenols, and a base-catalyzed aerobic cross-dehydrogenative coupling of thiophenols . All of the approaches mentioned above employ alkyl or aryl thiols as the starting materials.…”

“…Among them are an N-chlorosuccinimide-promoted cross-coupling reaction of alkyl thiols with aryl Grignard reagents, 10 an EDA-based visible lightmediated decarboxylative alkylation of thiophenols with Nhydroxy phthalimide esters as alkyl radical precursors, 11 an arylation of alkyl thiols with diaryliodonium salts, 12 an aryl halide-promoted visible light-induced C(sp 3 )−H bond thiolation with thiophenols, 13 and a base-catalyzed aerobic crossdehydrogenative coupling of thiophenols. 14 All of the approaches mentioned above employ alkyl or aryl thiols as the starting materials. The difficulties encountered in handling foulsmelling, readily oxidizable, toxic, and in some cases volatile thiols hinder their practical application.…”