FOLDED CONFORMATIONS OF N-(AMINOALKYL)-9-PHENANTHRENECARBOXAMIDES IN THE CRYSTAL AND SOLUTION

The molecular structures of three tertiary N-(aminoalkyl)-9-phenanthre necarboxamides were investigated in solution and the solid state by me ans of H-1 NMR spectroscopy and x-ray crystallography. The tertiary am ides exist as a mixture of E and Z tromers in solution and the aminoal kyl groups exist as a mixture extended and folded conformers. A crysta lline N-(aminoethyl)amide was obtained as the pure Z isomer in which t he phenanthrene and amide planes are nearly perpendicular and the amin oethyl group is folded over the less hindered face of the amide group. Rotation about the Ar-C(Of bond Is slow in resolution rendering these molecules chiral on the NMR time-scale. As a consequence, the cu-meth ylene protons display large diasterotopic splittings when the aminoalk yl group is syn to the amide carbonyl. Folded conformations place the Z and E aminoalkyl groups in the deshielding and shielding regions, re spectively, of the phenanthrene rings, resulting in large differences in chemical shifts. (C) 1997 by John Whey & Sons, Ltd.