Lewis Acid-Catalysed Oxidative Cycloaddition of Thiophenes1
31 December 2000 (online)
Thiophenes 1 have been treated with m-CPBA under BF3⋅Et2O catalysis. The thiophene-S-monoxides intermediary produced have been reacted in situ with various dienophiles. It could be shown that Lewis acid catalysis enhances the yield of the oxidative cycloaddition of thiophenes considerably. Moreover a greater variety of dienophiles can be used in the corresponding uncatalysed reaction. Thiophene-S-monoxides have also been isolated and subjected to subsequent cycloaddition in a two-step procedure.
cycloaddition - Lewis acid - thiophene-S-monoxide