Synthesis of Unsymmetrically and Highly Substituted Thiophenes Utilizing Regioselective Ring-expansion of gem-Dichlorocyclopropyl Ketones with Lawesson’s Reagent

Ring-expansion of aryl gem-dichlorocyclopropyl ketones 1 using Lawesson’s reagent afforded unsymmetrically and highly substituted 5-chloro and 3-chlorothiophenes 2 and 3 with excellent regioselectivity. The Suzuki–Miyaura coupling of 2 and 3 with PhB(OH)2 was successfully performed to give 2-aryl-3-methyl-5-phenylthiophenes 4 and 2-aryl-3-methyl-4,5-diphenylthiophenes 5, respectively.