Access to Substituted Thiophenes through Xanthate-Mediated Vinyl C(sp<sup>2</sup>)-Br Bond Cleavage and Heterocyclization of Bromoenynes
Guoling Huang, Jian Li, Jian‐Rong Li, Jiaming Li, Minghua Sun, Peng Zhou, Lu Chen, Yubing Huang, Shaohua Jiang, Yibiao Li
Abstract
An environmentally sustainable strategy for the chemoselective heterocyclization of bromoenynes through a transition-metal-free sulfuration/cyclization process is reported. Using inexpensive and safe EtOCS2K as a thiol surrogate and tetrabutylphosphonium bromide and H2O as a mixed solvent, the reaction provided a range of substituted thiophenes in moderate to good yields. In addition, 2,3,4,5-tetrasubstituted thiophenes were able to be prepared under mild reaction conditions by electrophilic heterocyclization with NH4I and EtOCS2K in good yields.
Topics & Concepts
ChemistryXanthateElectrophileVinyl bromideBromideBond cleavageSolventTransition metalChemoselectivityOrganic chemistryThiolCleavage (geology)Medicinal chemistryPolymer chemistryCombinatorial chemistryCatalysisEngineeringGeotechnical engineeringFracture (geology)Sulfur-Based Synthesis TechniquesChemical Synthesis and ReactionsCatalytic C–H Functionalization Methods