The di-π-methane rearrangements of 1,4-dihydro-1,4-methano- and -ethanonaphthalene-5,8-diols

Abstract

Direct photolysis of 1,4-dihydro-1,4-methanonaphthalene-5,8-diol (1a) gave tetracyclo[5.4.0.0^2,4.0^3,6]undeca-1(7),8,10-triene-8,11-diol (2a), the structure of which was established by spectral data and conversion into the known diacetate (2b). Photolysis of the 1,4-ethano-derivative (1g) gave tetracyclo[6.4.0.0^2,4.0^3,7]dodeca-1(8),9,11-triene-9,12-diol (2d), identified from spectral data. An X-ray crystallographic study of its diacetate (2e) showed that the crystals are orthorhombic, space group Pnma, a= 8.37(2), b= 18.60(3), c= 9.49(2)Å, Z= 4, with 50% occupation of equivalent positions by enantiomer pairs to produce a disordered structure. The structure was solved by direct methods and atomic positions and thermal parameters were refined by full-matrix least-squares calculations and Fourier methods. Studies with the 2,3,6,7-tetradeuterio-derivatives of (1a) and (1g) showed that the rearrangements are of the di-π-methane–vinylcyclopropane type.