Folded conformations of N-(aminoalkyl)-9-phenanthrenecarboxamides in the crystal and solution

✍ Scribed by Frederick D. Lewis; Eric L. Burch; Charlotte L. Stern

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 96 KB
• Volume: 10
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199707)10:7<525::aid-poc909>3.0.co;2-f

✦ Synopsis

The molecular structures of three tertiary N-(aminoalkyl)-9-phenanthrenecarboxamides were investigated in solution and the solid state by means of 1 H NMR spectroscopy and x-ray crystallography. The tertiary amides exist as a mixture of E and Z isomers in solution and the aminoalkyl groups exist as a mixture extended and folded conformers. A crystalline N-(aminoethyl)amide was obtained as the pure Z isomer in which the phenanthrene and amide planes are nearly perpendicular and the aminoethyl group is folded over the less hindered face of the amide group. Rotation about the Ar-C(O) bond is slow in resolution rendering these molecules chiral on the NMR time-scale. As a consequence, the ␣-methylene protons display large diasterotopic splittings when the aminoalkyl group is syn to the amide carbonyl. Folded conformations place the Z and E aminoalkyl groups in the deshielding and shielding regions, respectively, of the phenanthrene rings, resulting in large differences in chemical shifts.