Visible-Light-Enabled Construction of Thiocarbamates from Isocyanides, Thiols, and Water at Room Temperature

Abstract

A convenient visible-light-induced method for the synthesis of thiocarbamates from isocyanides, thiols, and water has been developed under mild reaction conditions. The present protocol offers a cost-effective and operationally straightforward approach to the various thiocarbamates in moderate to good yields by simple use of cheap Rose Bengal as the photocatalyst and water as the reaction reagent as well as an environmentally benign cosolvent.

Photocatalytical and Photochemical Generation of Imidoyl Radicals: Synthetic Applications

“…Again in 2018, Wei et al demonstrated a photocatalytic strategy for the synthesis of thiocarbamates 167 from thiols 165, isocyanides 166 and water in good to excellent yields (Scheme 35). [78] The use of water as a co-solvent, as well as an oxygen source, made this strategy green and sustainable. The authors propose that RB upon excitation to RB* [RB*/RB *À ; E 1/2 = + 0.99 V vs. SCE], undergoes reductive quenching with the thiol [E 1/2 = + 1.1 to + 2.1 V vs. SCE] [46] to give a thiol radical cation and RB *À .…”

Visible Light Mediated Sulfenylation‐Annulation Cascade of Alkyne Tethered Cyclohexadienones

“…Organic xanthate dyes like Eosin Y, Rose Bengal and Rhodamine B have evolved as a greener alternative for the generation of these radicals . Elegant organic photoredox mediated sulfenylation reactions like thiol‐ene, thiol‐yne, arylations, phosphonylation, spirocyclization and amidation have been reported. Inspired by these reports, we envisioned developing an organo‐photocatalytic thiol‐yne/annulation cascade of alkyne‐tethered cyclohexadienones using readily available thiols to gain access to sulfenylated dihydrochromenones (Scheme c).…”

KI-catalyzed synthesis of S-Thiocarbamates by cross-coupling of cyclohexyl isocyanide with sulfonyl chlorides

“…Therefore, the development of new methods for the synthesis of S-thiocarbamates is of widespread interest. Classic methods for the synthesis of S-Thiocarbamates include (1) reacting toxic phosgene/triphosgene or carbonyldiimidazole with an amine and thiophenol (Scheme 1(a)), 14,15 (2) visible-light/ rose bengal reactions (Scheme 1(b)), 7,16 and (3) molecular iodine-catalyzed reactions of thiosulfonates (prepared from thiols or sulfonyl chlorides) with isocyanides (Scheme 1(c)). 17 However, these methods have shortcomings such as poor atom economy, harsh reaction conditions, and the use of difficult-to-obtain precursors as well as unstable, toxic, and/or hazardous chemical reagents.…”