Study On The Synthesis Of 2,4-Diacylthiophene With Propargyl Alcohol And ?-Oxo Ketene Dithioacetals

Although thiophene with various functional group substitutions is the basic structural unit of a variety of bioactive compounds and photoelectric materials,there are still few synthetic pathways from sulfur-containing aliphatic materials to acylated thiophene,and no direct synthesis of 2,4-diacylthiophene has been reported.In this paper,we describe an efficient,metal-free,three-step,one-pot synthesis method that can be used to obtain iodivinyl dihydrothiophene from the simple and readily available starting materials propargyl and dithiophenone through bronsted-acid-catalyzed alkylation and iodine-catalyzed cyclezation.Subsequently,under the action of visible light,deiodized oxidation occurs,resulting in tetrachronous substitution of 2,4-diacylthiophene,and the synthesis of 2,4-diacylthiophene in one pot can be realized.The main feature of this method is relay catalysis,which integrates propargylation catalyzed by bronsteic acid,electrophilic cyclinization mediated by molecular iodine and visible light induced deiodization.The product iodivinyl dihydrothiophene can be derived conveniently by alkali catalysis and cross-coupling reaction.2,4-diacylthiophene can rapidly synthesize analogues of known bioactive compounds under the action of m-chloroperoxybenzoic acid.At the same time,2,4-diacylthiophene and diazoides after the reaction,can be obtained four-substituted thiophene and thiophene.Here,we have established a general strategy for the synthesis of 2,4-diacylthiophene with diverse structures through chemical catalysis and photochemical catalysis.Our strategy of continuous reaction opens the way for a method of synthesizing heterocycles from simple precursors by relay catalysis.