Reactivity of Anodically Generated 4-Methoxystilbene Cation Radicals: The Influence of Ortho-Substituted Hydroxymethyl, Aminomethyl, and Carboxylic Acid Groups
作者:Kam-Weng Chong、Noel F. Thomas、Yun-Yee Low、Toh-Seok Kam
DOI:10.1021/acs.joc.8b02360
日期:2018.12.21
The effect of ortho′-substituted side chains bearing nucleophilic groups such as CH2OH, CH2NHR, and CO2H on the reactivity of anodically generated 4-methoxy- and 3,4-dimethoxystilbene cation radicals was investigated, and results were compared with those of substrates where the nucleophilic groups such as OH and NHR are directly attached to the aromatic ring. It was found that when ortho′-substituted
研究了带有CH 2 OH,CH 2 NHR和CO 2 H等亲核基团的邻位取代侧链对阳极生成的4-甲氧基和3,4-二甲氧基methoxy阳离子自由基反应性的影响,结果是与亲核基团(例如OH和NHR)直接连接到芳环的底物相比。研究发现,当另一个环上存在邻位取代基(例如CH 2 OH或CH 2 NHR)时,只有直接的分子内阳离子亲核反应会发生,从而生成双苯并吡喃或双异喹啉。交叉产物(先前在邻位取代基为OH和NH 2时获得),例如未形成稠合的苯并x庚酮/稠合的苯并氮杂nes酮。当邻位取代基为COOH时,直接发生分子内阳离子-亲核反应,从而以高收率得到相应的双-δ-内酯。由于竞争性的芳族取代反应,另外的3-甲氧基取代基的存在导致其他稠合多环产物的形成。提出了导致不同产物的反应途径以及本斯蒂芬苯酯所表现出的行为差异的原因。结果为阳极产生的二苯乙烯阳离子自由基的反应性和行为提供了更多的见解。