Synthesis and crystal structures of α-phenyl- and α-trifluoromethyl-α-(2-pyridyl-N-oxide)ethanols and α-phenyl-α-(2-pyridyl-N-oxide)ethylene

摘要

The X-ray structures of two α-substituted α-(2-pyridyl-N-oxide) ethanols, the α-phenyl- (3a) and α-trifluoromethyl- (3b) derivatives, were determined. On dehydration of 3a, compound 4a was obtained. This study brought a clear proof that the α-(2-pyridyl-N-oxide)ethanols are formed following oxidation with peroxides of their corresponding pyridines. A different molecular packing was observed for the α-trifluoromethyl derivative due to an additional hydrogen bonding. Compound 3a crystallized in the monoclinic space group P 2_1 with unit cell parameters a = 5.7416(1) ?, b = 14.3841(4) ?, c = 13.2821(3) ?, β = 94.918(2)°, V = 1092.90(4) ?~3, Z = 4, D = 1.308 Mg/m ~3. Compound 3b crystallized in the triclinic space group P -1 with unit cell parameters a = 6.1209(2) ?, b = 8.1938(4) ?, c = 9.4675(4) ?, α = 73.363(3)°, β = 73.166(3)°, γ = 71.659(3)°, V = 421.32(3) ?~3, Z = 2, D = 1.633 Mg/m ~3. Compound 4a crystallized in the monoclinic space group P 2 _1 with unit cell parameters a = 9.3579(3) ?, b = 12.7340(3) ?, c = 9.8579(3) ?, β = 117.3249(15)°, V = 1043.63(5) ?~3, Z = 4, D = 1.255 Mg/m~3.