alpha-naphthyl phenyl pinacols

Treatment of alpha-naphthyl phenyl ketone with Zn/acetic acid gives racemic alpha-naphthyl phenyl pinacol [1,2-di(1-naphthyl)-1,2-diphenylethane-1,2-diol], C34H26O2, but reaction with Mg/MgI2 gives a product which proves to be not a pinacol, but a tricyclic compound (with four chiral centers, formed by addition at the 2-position of one of the naphthalene groups), racemic 5-(1-naphthyl)-3,5-diphenyl-4-oxatricyclo[7.4.0.0(2,6)]trideca-7,9,11,13 -tetraen-3-ol, C34H26O2 The aromatic ring in this tricyclic compound is planar, but the other six-membered ring, and the five-membered furano ring, are non-planar. Bond lengths and angles in both molecules correspond to the molecular formulations. In both structures, the OH groups are involved in only weak intermolecular interactions.