Preparation of Polycyclic Systems by Sequential 5-<i>E</i><i>xo</i>-<i>D</i><i>igonal</i> Radical Cyclization, 1,5-Hydrogen Transfer from Silicon, and 5-<i>E</i><i>ndo</i>-<i>T</i><i>rigonal</i> Cyclization
作者:Derrick L. J. Clive、Wen Yang、Aaron C. MacDonald、Zhongren Wang、Michel Cantin
DOI:10.1021/jo001124x
日期:2001.3.1
diagonal cyclization, and the resulting vinyl radical abstracts hydrogen from silicon to afford a silicon-centered radical. This radical closes in a 5-endo trigonal manner to generate radicals of type 4, which are reduced (4 --> 5) by stannane, except when the starting acetylene carries a terminal trimethylstannyl group. In this case, radicals 4 expel trimethylstannyl radical to afford vinyl silanes
类型1的基团经历5-exo对角环化,并且所得的乙烯基自由基从硅中提取氢以提供以硅为中心的自由基。该自由基以5-内三角键关闭,生成4型自由基,该自由基被锡烷还原(4-> 5),除非起始乙炔带有末端三甲基锡烷基。在这种情况下,自由基4排出三甲基锡烷基以提供乙烯基硅烷6。自由基级联1→5的立体化学结果受1中含氧碳的立体化学控制(请参阅加星标的原子)。该序列可以由碳,α-取代的碳,氧酰基和氨基甲酰基基团起始,并产生稠合到碳环或杂环上的含硅环。描述了许多示例,