A study of conformational behaviour in some hexahydro-2H-isoxazolo[2,3-a]pyridines

作者：Ali Shaikh A^*; AlSbaiee Alaaeddin; Wazeer Mohamed I M

来源：Arkivoc, 2008, 96-106.

• Isoxazoldines
• (13)C chemical shifts
• nitrogen inversion
• invertomers
• inversion barriers

A study of the effects of substituents on the conformational behaviour of a series of hexahydro-2H-isoxazolo[2,3-a]pyridines (a 6/5 fused ring system), prepared via nitrone cycloaddition reaction of 4-butyloxycarbonyl-3,4,5,6-tetrahydropyridine-1-oxide with mono- and disubstituted alkenes, has been carried out. Some of these bicyclic cycloaddition products show the presence of two isomers (cis- and trans-fused system), equilibrating via relatively slow nitrogen inversion process, while the rest exist solely as the trans-invertomer. Stereochemistry of the ring fusion was determined by NMR spectral analyses. The effect of substituents and solvents - CDCl(3) toluene-d(6), and CD(3)OD - on the population ratio of the invertomers and inversion barriers has been investigated. The nitrogen inversion barriers, determined using complete line-shape analysis, are in the range 62.1-72.3 kJ mol(-1)

• 出版日期2008
• 单位中国石油大学（北京）