The structures of two cycloadducts (1 and 2) of cyclopropenes to 1 ,3-diphenylisobenzofuran and trans-1-phenylbutadiene are established by X-ray crystallography. Both are exo adducts. In 2 the phenyl substituent occupies a pseudo-axial position; the ring-flipped conformation (2a) with the phenyl ring pseudo-equatorial is not observed.