Chemistry Letters, Vol.36, No.1, 62-63, 2007
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.