A Novel Intramolecular Photocyclization ofN-(2-Bromoalkanoyl) Derivatives of 2-Acylanilinesvia 1,8-Hydrogen Abstraction
作者:Takehiko Nishio、Hiroyuki Koyama、Daigo Sasaki、Masami Sakamoto
DOI:10.1002/hlca.200590095
日期:2005.5
The photochemical reactions of different N-(2-acylphenyl)-2-bromo-2-methylpropanamides have been investigated. Irradiation of the N-unsubstituted anilides 1a–1c gave the corresponding dehydrobromination, cyclization, and bromo-migration products 2, 3, and 4, respectively (Table 1). Irradiation of the N-alkyl anilides 1e–1g afforded the corresponding deacylation and cyclization products 5 and 6, respectively
已经研究了不同的N-(2-酰基苯基)-2-溴-2-甲基丙酰胺的光化学反应。N-未取代的苯甲酸酯1a - 1c的辐照分别给出了相应的脱氢溴化,环化和溴迁移产物2、3和4(表1)。辐照N-烷基苯甲酸酯1e - 1g分别提供相应的脱酰基和环化产物5和6,而辐照N-烷基苯甲酸酯1i - 1k在芳族环上带有2-苯甲酰基的R 2,提供了出乎意料的三环内酰胺7(除2,5和6之外)。环化产物的形成6可在6的电环环闭合的角度来合理化π π电子共轭的烯酰胺2通过脱溴化氢的产生1,其次是热1,5-酰基迁移(B路径的方案)。桥接内酰胺7的形成可能遵循一种机制,该机制涉及由ζ生成的1,7-双自由基8通过激发的酰基O原子(路径A)进行-H-抽象(1,8-H转移)。