Anisotropic effects in α-substituted methoxystilbenes

The relative upfield chemical shift of a meta-substituted methoxy-group upon one of the rings of a cis-stilbene gives an indication of the conformational preferences of the molecule. In E-α-nitrostilbenes the β ring spends more time than the α ring in planarity with the olefin bridge. In E-3-benzylideneindole-2(3H)-ones the arylidene ring does not achieve planarity with the indolone. Assignments of configuration to the 3′,4′-dimethoxy α-nitrostilbenes and the 3′,4′-methylenedioxy-analogues have been corrected.