NOVEL AND CONVENIENT METHODS FOR THE PREPARATION OF SUBSTITUTED THIOPHENES, THIAZOLES, AND 1,3,4-THIADIAZOLE-2(3H)-THIONES FROM BIFUNCTIONAL SUBSTRATES

Abstract

The reactions of LR (Lawesson’s Reagent) with 4-oxocarboxylic acid derivatives I, N-acyl aminoacid derivatives III, and N-acyl-N′-ethoxycarbonylhydrazines V, smoothly produce substituted thiophenes II, thiazoles IV, and 1,3,4-thiadiazole-2(3H)-thiones VI.

Versatile assembly of 5-aminothiazoles based on the Ugi four-component coupling

“…Refluxing with Lawesson's reagent in toluene resulted in efficient thionation but little formation of the thiazole. In line with Lawesson's brief initial studies on glycine derivatives, 15 we found that a higher temperature reflux in m-xylene was required to drive the cyclisation, conversion to 9a being essentially complete in 1 h.…”

DFT-assisted design and evaluation of bifunctional copper(I) catalysts for the direct intermolecular addition of aldehydes and ketones to alkynes

“…Amide coupling with threonine methyl ester 13, followed by Dess-Martin Periodinane (DMP) oxidation, yielded the known dipeptidyl ketone 16 in good yield. Heating with Lawesson's reagent provided the thiazole 17 [44], followed by Nbenzylation using sodium hydride and benzyl bromidein DMF to give 18. Reduction of the ester proceeded cleanly with sodium borohydride and catalytic sodium triacetoxyborohydride.…”

Design and Synthesis of Oxazoline-Based Scaffolds for Hybrid Lewis Acid/Lewis Base Catalysis of Carbon–Carbon Bond Formation

“…[α] D 25 Alcohol 9 (3.60 g, 10.9 mmol) was added to a 250-mL round-bottom flask containing CH 2 Cl 2 (150 mL) and DMP (5.08 g, 12.0 mmol). The mixture was stirred at r.t. for 1 h before water was added (0.816 g, 45.3 mmol), then stirred for a further 1 h before the consumption of the starting material was observed (LC-MS).…”