Preparation of Thiazole-2-thiones through TBPB-Promoted Oxidative Cascade Cyclization of Enaminones with Elemental Sulfur

Abstract

An unprecedented method for the construction of thiazole-2-thiones via an oxidative cascade cyclization strategy is described. The novel protocol involves the simultaneous formation of two CS bonds and a CS bond on the structure of enaminones in a single operation through a cascade of C­(sp2)H/C­(sp3)H bond sulfurations and C­(sp3)–H bond thiocarbonylation. This transformation allows for the efficient synthesis of thiazole-2-thiones with broad tolerance in moderate to excellent yields from simple enaminones with elemental sulfur.

A stepwise one-pot synthesis of aliphatic thiols and their derivatives from acrylamides and sulfur

“…CvN double bonds, 39,40 isocyanides, 29,37,[41][42][43] isothiocyanates 44 and iodonium salts. 45 Recently, a handful of new methods exploited the divergent reactivity of chalcones 36,[46][47][48][49] and β-oxo-enamines 35,[50][51][52][53][54] towards sulfur giving access to the selective formation of sulfur containing heterocycles and other structures (Scheme 2). In fact, Retailleau and Nguyen demonstrated that starting from chalcones, the careful selection of the base may enable the selective formation of either sultams or benzothiophenes.…”

Recent advances in transition metal-free annulation toward heterocycle diversity based on the C–N bond cleavage of enaminone platform

“…Actually, both transformation modes have found broad and significant application in devising highly enriched synthetic methods. The reactions employing enaminones as CC–N building blocks without cleaving the C–N bond have been successfully utilized for the synthesis of diverse organic compounds such as pyrroles and derivatives, 2 oxazoles, 3 imidazoles, 4 thiazoles, 5 triazoles, 6 indoles, 3 d ,7 pyridinones, 8 quinolones, 8 b pyrimidines, 9 triazines 10 and other nitrogen-containing compounds. 11 Research advances on such reactions of enaminones have just been reviewed by Xia and Niu.…”

A NaHCO3 Promoted Three‐component Cyclization: Easy Access to Benzodisulfide Heterocycles

“…Sulfur-containing heterocycles as an important class of compounds show significant potential for their multiple functions, especially exhibit attractive biological and pharmacological properties, such as anti-inflammatory, antimicrobial, anti-tuberculosis, and anti-HIV activity, etc. [1][2][3] Therefore, the synthesis of sulfur-containing heterocyclic compounds has attracted great attention in modern organic chemistry. [4][5][6][7] Different sulfur sources, [8] e. g., potassium sulfide, [9] thiocyanate, [10] thiourea, [11] isothiocyanate, [12] thioamide, [13] thiophenol, [14] and elemental sulfur (S 8 ), [15] can be used to construct sulfur-containing heterocyclic compounds.…”

“…Sulfur‐containing heterocycles as an important class of compounds show significant potential for their multiple functions, especially exhibit attractive biological and pharmacological properties, such as anti‐inflammatory, antimicrobial, anti‐tuberculosis, and anti‐HIV activity, etc [1–3] . Therefore, the synthesis of sulfur‐containing heterocyclic compounds has attracted great attention in modern organic chemistry [4–7] .…”