4,7-diphenylisobenzofuran: a useful intermediate for the construction of phenyl-substituted acenes.

The formation and subsequent reactivity of previously unknown 4,7-diphenylisobenzofuran, 5, is reported. The Diels-Alder reaction between 5 and p-benzoquinone in boiling glacial acetic acid yields an unprecedented exo,exo anti dual cycloaddition product, 16b, in excellent yield and with 100% diastereoselectivity. Differences between the reactivities of 5 and the more common 1,3-diphenylisobenzofuran are highlighted. Reactive 5 is utilized to form new three-, four-, and five-ring acenes, and the latter compound is reacted with [60]fullerene to produce new [60]fullerene-acene adducts.