2 RELATED BENZYLCAMPHOR DIMERS

The crystal structures of two related dimeric 3-benzyl-camphors, namel y, iphenylethylene]bis(1,7,7-trimethylbicyclo[2.2.1]- heptan-2-one), ( 1), and (1R,3R,4R, 1'R,3'S,4'R)-3,3'- [(1R,2S)-1,2-diphenylethylene] b is(1,7,7-trimethylbicyclo-[2.2.1]heptan-2-one), (2), both C34H42O2, ar e reported. Compound (1) possesses C-2 molecular symmetry; it adopts a conformation in the crystal in which the two phenyl rings are gauche with respect to one another and anti to the C3-C4 bond (terpene number ing) of the camphor ring system. Compound (2) lacks a molecular C-2 ax is of symmetry; it adopts a conformation in the crystal where the two phenyl rings are anti with respect to one another, and in which one ph enyl ring is partially in the endo cavity of the camphor ring system. In both compounds, C3 of both camphor ring systems (terpene numbering) is distorted to trigonal pyramidal from tetrahedral; the C-C-C bond a ngles about C3 in both camphor rings are considerably expanded from id ealized tetrahedral values and the dihedral angle between the benzyl C atom and the carbonyl O atom is reduced from the idealized value of 6 0 degrees to less than 48 degrees.