Regioselectivity of Diels-Alder reactions between 6,7-dehydrobenzofuran and 2-substituted furans

We describe the first report of the generation of 6,7-dehydrobenzofuran(6,7-benzofuranyne) from 6,7-dihalobenzofurans via metal-halogen exchange and elimination, in a manner similar to our previous work with 6,7-indole arynes. This benzofuranyne undergoes highly regioselective Diels-Alder cycloadditions with 2-substituted furans.