Dualortho interaction in 2-substituted-3-(2-methylphenyl)-4(3H)-quinazolinones and their thio analogues under electron impact conditions
作者:D. V. Ramana、E. Kantharaj
DOI:10.1002/jms.1190300206
日期:1995.2
Competing ortho interactions, involving the CX and the ortho-methyl substituent on the 3-phenyl moiety, resulting in the eliminations of ˙CH3 and ˙OH/˙SH from the molecular ions of 2-substituted-3-(2-methylphenyl)-4(3H)-quinazolinones and their thio analogues, were observed. An intramolecular aromatic substitution of the heteroatom of CX at the ortho-carbon of the 3-phenyl moiety ejecting the methyl group and a hydrogen transfer from the same ortho-methyl substituent to the heteroatom of CX resulting in the expulsion of ˙XH are envisaged for the dual ortho interaction. Another expected fragmentation process observed in these compounds is the transfer of the aryl group from the 3-position of the heterocycle to the heteroatom of CX leading to the elimination of ArX˙ from the molecular ions. The proposed fragmentation processes and the ion structures are supported by high-resolution data, B/E and B2/E linked-scan spectra, collisionally activated decomposition B/E spectra and deuterium isotopic labelling.
CX 和 3-苯基上的正交甲基取代基之间的正交作用相互竞争,导致 2-取代-3-(2-甲基苯基)-4(3H)-喹唑啉酮及其硫代类似物分子离子中的˙CH3 和˙OH/˙SH 消去。预计在双正交作用中,CX 的杂原子在 3-苯基的正交碳上发生了分子内芳香取代反应,从而释放出甲基,同时同一正交甲基取代基的氢转移到 CX 的杂原子上,导致释放出 ˙XH。在这些化合物中观察到的另一个预期碎裂过程是芳基从杂环的 3 位转移到 CX 的杂原子,导致 ArX˙从分子离子中消除。高分辨率数据、B/E 和 B2/E 链接扫描光谱、碰撞激活分解 B/E 光谱和氘同位素标记支持了所提出的碎裂过程和离子结构。