1,3-Diaryl Isobenzofurans from Arylboronic Acids and ortho-Keto Aldehydes

Significance

Reported is the synthesis of isobenzofurans, involving the catalytic addition of an arylboronic acid to an ortho-keto aldehyde, followed by ring closure and elimination of water. Several different catalytic systems were implemented, with varying degrees of success. The use of microwave heating was extremely useful in certain cases, most notably for boronic acids containing reactive or sterically hindered functional groups. In one particular case (R = I, Ar = Ph) the use of microwave heating changed the path of the reaction and the isobenzofuran product was obtained in 70% yield, in place of the Suzuki product, which was formed under standard heating conditions in 74% yield. This change of reaction with microwave heating is suggested to be due to the formation of a different catalytic system from that of the conventional heating conditions.