The chemistry of the “insoluble red woods.” Part 15. The crystal structures of 7-benzyloxy-6,2′,3′,4′-tetramethoxy- and 2,6,7,2′,3′,4′-hexamethoxy-isoflav-3-ene

The reaction of 7-benzyloxy-6,2,3,4-tetramethoxyisoflavylium perchlorate with 1-(2,4-dimethoxyphenyl)-3-(3,4-dimethoxyphenyl)-prop-l-ene and of 6,7,2,3,4-pentamethoxyisoflavylium perchlorate with the same propene yielded respectively 7-benzyloxy-6,2,3,4-tetramethoxyisoflav-3-ene (5) and 2,6,7,2,3,4-hexamethoxyisoflav-3-ene (7) whose structures have been established by X-ray crystallography. Crystals of (5) are monoclinic, space groupP2₁/a (No. 14) with four molecules in a unit cell of dimensionsa=8.528(2),b=13.294(3),c=19.629(4) Å,=99.92(2)°. Crystals of (7) are also monoclinic, space groupC2/c (No. 15) with eight molecules in a unit cell of dimensionsa=28.088(3),b=10.662(3),c=12.869(1) Å,=97.32(1)°. Both structures were solved by direct methods and refined by full-matrix least-squares calculations to finalR values of 0.053 and 0.041 for 1673 and 1424 observed data for (5) and (7) respectively. The molecular dimensions are in accord with accepted values.For Part 14 see Whalley, W. B., Ferguson, G., and Khan, M. A., (1980)J. Chem. Res. (M), 2219.