作者:John A. Barltrop、A. Colin Day、Arthur G. Mack、Aziz Shahrisa、Shigeru Wakamatsu
DOI:10.1039/c39810000604
日期:——
Cyano-substituted pyrazoles transpose photo-chemically into imidazoles by two concurrent paths: (a) 1,5-interchange, probably by 2,5-bonding to a diazabicyclopentene which isomerises by nitrogen ‘walk’ before rearomatisation, and (b) 2,3-interchange, probably via an intermediate azirine; in sharp contrast, 1,5-dimethyl-3-trifluoromethylpyrazole phototransposes exclusively by the former path.
氰基取代的吡唑通过两种同时的途径以光化学方式转变为咪唑:(a)1,5-交换,可能通过2,5-结合至二氮杂双环戊烯,该二氮杂双环戊烯在重新芳构化之前通过氮的“游走”而异构化;和(b)2 3-互换,可能是通过中间的叠氮基进行的;与之形成鲜明对比的是,1,5-二甲基-3-三氟甲基吡唑仅通过前者的路径进行光转位。