Copper-Catalyzed Thiolation of Terminal Alkynes Employing Thiocyanate as the Sulfur Source Leading to Enaminone-Based Alkynyl Sulfides under Ambient Conditions

Abstract

A highly efficient protocol for copper-catalyzed thioalkynylation of enaminone-based thiocyanates with terminal alkynes under mild conditions has been developed. This scalable amino group-directed thio-alkynylation proceeds in the open air with a broad substrate scope and an excellent yield. The demonstrated synthetic transformation creates the opportunity for a wide variety of sulfur-containing useful materials. Gram-scale synthesis and further synthetic transformations of alkynyl sulfides highlight the potential utility of the method.

Highly Selective C–N and C–S Dual Functionalization of 1,3-Dicarbonyl Derivatives Using TBHP as an Oxidant

“…The cyclization of 3d with cesium carbonate gave amino-thiazole 18a in 48% yield. The treatment of 3d with phenylacetylene afforded a compound 18b in 50% yield . The cyclization of 3d using 50% sulfuric acid gave corresponding thiazolinone ( 18c ).…”

Alkyne/thio umpolung tactic replacement: synthesis of alkynyl sulfides via capturing the in situ formed alkynylthiolate anion

“…Meanwhile, a sulfur umpolung-type strategy was also applied in alkynyl sulfide synthesis, showing that the C–S bond could be formed through the manipulation of a leaving group on sulfur, typically employing a copper- or a rhodium-catalyzed coupling with sulfur-electrophiles or by nucleophilic substitution of sulfur halides or Bunte salts. 9 Surprisingly, the alkynylthio transfer approach for the synthesis of alkynyl sulfides is rare in the toolbox of synthetic chemists, which is mainly due to the absence of general methods to obtain the alkynylthiolating reagents. Very recently, Alcarazo and Gao, respectively, reported the electrophilic alkynylthiolating reagents N -alkynylthio phthalimide and alkynylthioimidazolium salt for alkynyl sulfide synthesis (Fig.…”