Molecular Structure of Heterocycles: NMR Spectroscopy, Semiempirical MO Calculations and X-Ray Diffraction of 3,3a,4,5,6,7-Hexahydro-3-trichloromethyl[2,1]benzoisoxazole

Abstract

1H and 13C NMR data, AMI calculations and X-ray diffraction in 3,3a,4,5,6,7-hexahydro-3-trichloromethyl[2,1]benzo isoxazole (1), obtained from the cyclization of trichloroacetyl cyclohexanone with hydroxylamine, are reported. 1H and 13C NMR data shown that only one pair of the diastereoisomers was obtained and the AMI calculations indicated that 1a (3S3aS/3R3aR) is 2.63 kc:al.mol−1 more stable than 1b (3S3aR/3R3aS). The X-Ray diffraction data confirmed that only the structure 1a was obtained. Crystals of 1 (C8H10Cl3NO2, Mr = 258.52) were obtained from acetone/n-hexane solution. The compound crystallizes in the monoclinic space group P21/c with the cell dimensions a = 10.153(2), b = 8.271(2) and c = 14.225(3) Å, β = 103.8(3)°, V = 1160.0(4) Å3, Z= 4, Dcalcd. = 1.480 Mg/m3, λ(MoKα) = 0.71073 Å, = 0.764 mm-1, F(000) = 528, T= 293(2) K, R = 7.31 % and Rw = 17.91 % for an F 2 refinement on unique data with 2082 reflections and 1994 independent (Rint = 6.70%) were collected.