Selective Arylation, Alkenylation, and Cyclization of Dibromonaphthols, Using Visible Light, via Carbene Intermediates
作者:Daniela Verga、Filippo Doria、Mariella Mella、Mauro Freccero
DOI:10.1021/jo900793b
日期:2009.8.7
presence of the base, for the unsubstituted naphthol, or heterolytic C−Br cleavage directly from the naphtholates, for the more acid 3-substutited naphthols (R = COOCH3, CONH2, CONMe2), generates electrophilic carbene intermediates, which have been successfully trapped by molecular oxygen, pyrrole, acrylonitrile, ethyl vinyl ether, and allyltrimethylsilane. Product distribution analysis reveals three
使用可见光(450 nm)在稀释的Et 3 N存在下,在纯乙腈中和在水性缓冲乙腈(pH 8,磷酸盐缓冲液)中研究了几种3-取代的1,6-二溴-2-萘酚的光反应性。)。对于未取代的萘酚,或直接从萘酚中裂解的C-Br裂解,对于存在更多酸的3取代萘酚,在碱存在下会发生氢溴酸损失(R = COOCH 3,CONH 2,CONMe 2)生成亲电卡宾中间体,该中间体已被分子氧,吡咯,丙烯腈,乙基乙烯基醚和烯丙基三甲基硅烷成功捕获。产物分布分析揭示了由(i)芳基化,(ii)烯基化和(iii)环化反应产生的三种类型的产物。激光闪光光解支持了作为亲电子双自由基的α-酮卡宾中间体的生成和反应性,同时检测了卡宾(λmax 510 nm)和1,2-萘醌-O-氧化物(R = CONMe 2,λmax 600 nm)在O 2的存在下。