Synthesis of beta-substituted 2,5-dibromothiophenes and their s,s-dioxides

Abstract

This research surveyed for suitable conditions to synthesize -substituted thiophene S,S-dioxides. Experimental factors under investigation included types of substituents at beta position, types of oxidizing agents, reaction time, temperature, and solvent. The products were analyzed by various spectroscopic methods. 2,5-dibromothiophene, 2,5-dibromo-3-hexylthiophene, 2,3,5-tribromothiophene, 2,5-dibromo-3-methoxythiophene, and 2,3-dibromothieno[3,4-b]-1,4-dioxin have been successfully prepared in 64%, 80%, 75%, 56%, and 63% yield, revealed respectively. The study on the oxidation of several thiophene derivatives found that thiophene oxidized by 30% H[subscript 2]O[subscript 2] in CH[subscript 3]CN, and 2,3-dibromothieno[3,4-b]-1,4-dioxin by Na[subscript 2]CO[subscript 3]. 1/2H[subscript 2]O[subscript 2] in CH[subscript 3]CN were likely to give the desired oxidized products