Combination of enzyme- and Lewis acid-catalyzed reactions: a new method for the synthesis of 6,7-dihydrobenzofuran-4(5H)-ones starting from 2,5-dimethylfuran and 1,3-cyclohexanediones.

The Lewis acid-catalyzed domino 1,2-addition/1,4-addition/elimination between (Z)-3-hexene-2,5-dione and 1,3-dicarbonyls delivers 3-methyl-6,7-dihydrobenzofuran-4(5H)-ones exclusively with yields up to 82%. The combination of this new process with the laccase-catalyzed formation of (Z)-3-hexene-2,5-dione by oxidative cleavage of 2,5-dimethylfuran allows for the synthesis of 6,7-dihydrobenzofuran-4(5H)-ones starting directly from 2,5-dimethylfuran.