Rhenium-Catalyzed Synthesis of Isobenzofurans

Significance

A rhenium-catalyzed synthesis of isobenzofurans from aldehydes and ketimines is reported. The reaction occurs by a sequential aromatic C-H activation, aldehyde insertion, cyclization and amine elimination to afford the isobenzofuran derivatives in good yields. The scope was not widely tested: benzaldehydes bearing electron-donating or -withdrawing groups and cinnamaldehyde participated well in the reaction. More interestingly, a one-pot procedure involving trapping of the isobenzofurans in inter- or intramolecular Diels-Alder reaction was also reported.