A Study On The Synthesis Of Thiophene Derivatives From Cyclopropanecarboxylates

Thiophene,containing a flat structure of electron-rich sulfur-containing aromatic heterocycle,is widely found in nature.Many of its derivatives are scaffolds of numerous important synthetic chemicals.For example,it plays an extremely important role in the fields of biomedicines,pesticides,and photoelectric materials.In view of these,effective construction of multi-substituted thiophene rings with different structures has attracted considerable attention among organic chemists.Based on the study of “Diversity-Oriented Synthesis” and the outstanding results achieved in cyclopropanecarboxylates in our laboratory,we made some research mainly on the application of this cyclopropane in the synthesis of thiophene derivatives.The details are summarized as follows:Firstly,we carried out the reaction of enone compounds with dichloroacetate in the presence of base,and synthesized a series of electron-deficient cyclopropane products in good yields.At the same time,we derived several representative D-A cyclopropanes which broaden the scope of the cyclopropane substrates in some aspects;Then,the reaction between ethyl 2-acyl-1-chlorocyclopropanecarboxylates and Lawesson's reagent was studied in the absence of any metal additives,which afforded some biologically active thiophene products with potential application value.Encouraged by this result,we focused on the optimization of the reaction conditions and obtained a series of alkyl thiophene-2-thiocarboxylate products at high yields(up to 91%).In addition,the possible reaction pathway was also proposed.This method provides an effective way for building this kind of compounds which enrich the diversity of thiophene derivatives to some extent;More,we studied the reaction of methyl 2-acyl-1-phenoxycyclopropanecarboxylates with Lawesson's reagent.And both disubstituted furan and thiophene were obtained during this reaction.Furthermore,we took the ratio of two products into consideration founding that the electronic properties of the substituents have a great influence on it.