Metal-Free Temperature-Controlled Intermolecular [3 + 2] Annulation to Access Benzo[d]thiazole-2(3H)-thiones and Benzo[d]thiazol-2(3H)-ones

Abstract

A facile access to benzo­[d]­thiazole-2­(3H)-thiones and benzo­[d]­thiazol-2­(3H)-ones has been developed through a temperature-controlled intermolecular [3 + 2] annulation of N,N-disubstituted arylhydrazines with CS2 in the presence of DMSO. This protocol can obviate the prefunctionalization of the starting materials. This direct C–S/C–N bond formation reaction was performed in the absence of any external catalysts, transition metals, bases, ligands, and oxidants with high step economy.

I2‐Promoted [3+2] Cyclization of Thiocarbamates with Enaminones: a Protocol for the Synthesis of Polysubstituted Thiazol‐2(3H)‐ones

“…[8] Guo and co-workers developed a facile access to benzo[d]thiazol-2(3H)-thiones and benzo[d]thiazol-2(3H)-ones through a temperature-controlled intermolecular [3 + 2] annulation in the presence of DMSO (Scheme 1c). [9] In 2022, the Saikia group successfully developed an efficient methodology for the synthesis of substituted thiazolones via [3,3]-sigmatropic rearrangement/5-exo-dig cyclization (Scheme 1d). [10] In 2022, Wan and Liu reported the first aerobic αÀ CÀ H thiocyanation of NH 2 -enaminones via visible light photocatalysis and the tunable synthesis of 2-aminothiazoles and 2-thiazolidinones (Scheme 1e).…”

Copper-Promoted Aerobic Oxidative [3+2] Cycloaddition Reactions of N,N-Disubstituted Hydrazines with Alkynoates: Access to Substituted Pyrazoles

“…Organic hydrazines are attractive synthetic intermediates for the construction of various N-containing organic compounds . Inspired by the recent work reported by our group in developing a series of green synthetic methodologies based on substituted hydrazines, we postulate to use N,N-disubstituted hydrazines as starting materials to synthesize pyrazoles.…”

DBU-Promoted Deaminative Thiolation of 1H-Benzo[d]imidazol-2-amines and Benzo[d]oxazol-2-amines

“…We also disclosed a base-promoted metal-/oxidant-free three-component tandem annulation for the synthesis of 2,4,5-trisubstituted thiazoles and 1 H -1,2,4-triazol-3-amines via C–N bond cleavage of amidines . Based on our previous report, we herein develop a facile and efficient 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU)-promoted deaminative thiolation reaction of 1 H -benzo­[ d ]­imidazol-2-amines and benzo­[ d ]­oxazol-2-amines using CS 2 as a convenient sulfur source without the requirement of any external catalysts, metals, and oxidants under room temperature (Scheme d). Various 2-thio-1 H -benzo­[ d ]­imidazoles and 2-thiobenzo­[ d ]­oxazoles are prepared through C–N bond cleavage and C–S bond formation process.…”