Molecular structures of regioisomeric 7-arylidene hexahydroindazoles from (1)H NMR spectra.

The structural characterization of two regioisomeric products of the interaction of 2,6-bis-(4-methoxybenzylidene)-3R-methylcyclohexanone with methyl hydrazine was achieved using (1)H NMR spectral data, including chemical shifts, coupling constants and results of COSY and nuclear overhauser effect (NOE) experiments. Configurations of the new chiral centers in the (3S,3aR,6R,7E)-7-(4-methoxybenzylidene)-3,4,5,7-hexahydro-3-(4-methoxyphenyl)-2,6-dimethyl- and 2,4-dimethyl-2H-indazoles were assigned on the basis of experimental data combined with molecular modeling by the density functional theory (DFT) method. The distinction in the helical twisting power of studied compounds under addition to a nematic liquid crystal is discussed on the basis of peculiarities of the molecular structures.