N-trifyl substituted 1,4-diheterocyclohexanes-stereodynamics and the Perlin effect

作者：Shainyan Bagrat A^*; Ushakov Igor A; Tolstikova Ljudmila L; Koch Andreas; Kleinpeter Erich

来源：Tetrahedron, 2008, 64(22): 5208-5216.

DOI：10.1016/j.tet.2008.03.047

• N-trifluoromethylsulfonyl derivatives of azinanes
• conformation
• dynamic NMR
• Perlin effect
• DFT calculations

The stereodynamic behaviour of 1-(trifluoromethylsulfonyl)piperidine 1, 4-(trifluoromethylsulfonyl) morpholine 2, 1,4-bis(trifluoromethylsulfonyl)piperazine 3 and 4-(trifluoromethylsulfonyl)thiomorpholine 1,1-dioxide 4 was studied by low-temperature H-1, C-13 and F-19 NMR spectroscopies. In acetone solution, compounds 1, 2 and 4 were found to exist as mixtures of two conformers in the ratio of 4:1,4:1 and 8:1, respectively, differing by orientation of the CF3 group with respect to the ring. Compound 3 exists as a mixture of three conformers in the ratio of 3:28:69 also differing by the orientation of the two CF3 groups. Unlike the previously studied N-trifyl substituted 1,3,5-triheterocyclohexanes, the preferred conformers of compound 1 and of 1,4-diheterocyclohexanes 2-4 are those with the CF3 group directed outward from the ring, which is caused by intramolecular interactions of the oxygen atoms of the CF3SO2N groups with the equatorial hydrogens in the a-position. B3LYP/6-311+G(d,p) calculations of the energy, geometry and NMR parameters corroborate the experimental data. The calculated Perlin effects for all conformers of compounds 1-4 as well as those measured for the major conformers of compounds 3 and 4 were analyzed by the use of the NBO analysis.

• 出版日期2008-5-26