Distant functionalization via incorporation of thiophene moieties in electrophilic reactions promoted by samarium diiodide

Abstract

Methyl thiophene-2-carboxylate, methyl 3-(thien-2-yl)acrylate, and methyl 5,2'-bithiophene-2-carboxylate were utilized as the synthetic equivalents of pentanoate 5-anion, pentanoate 4,5-dianion, heptanoate 7-anion, and nonanoate-8,9-dianion. By the promotion of samarium diiodide, these thiophene-incorporating compounds reacted with aldehydes, ketones, and conjugated esters regioselectively at the thienyl rings. Long-chain esters with remote hydroxyl and carboxyl groups, including an antiarthritis agent, a shellac component, and an inhibitory agent of spore germination, were prepared after reductive desulfurization on Raney nickel.