Rhodium-catalyzed cyclization of acceptor-substituted biphenyl α-diazoketones: a study of the substitution effect on chemoselectivity
作者:Kuo-Hsin Chen、Yi-Jung Chiang、Jia-Liang Zhu
DOI:10.1039/c8ob01489b
日期:——
rhodium(II)-catalyzed intramolecular cyclization. Among which, the α-acetyl, carboxylate and cyano substituted substrates show markedly different selectivity between aromatic substitution and aromatic cycloaddition processes, affording phenanthrol and/or benz[α]azulenone products in varying ratios. The selectivity is mainly directed by α-substitutions, and is also possibly influenced by the substituents
研究了重氮碳上一系列含有各种吸电子基团(EWG = COCH 3,CN,CO 2 Et,COPh,SO 2 CH 3,SO 2 Ph)的联苯α-二氮酮用于铑(II)催化的分子内环化。其中,α-乙酰基,羧酸酯和氰基取代的底物在芳族取代和芳族环加成过程之间显示出明显不同的选择性,从而提供了菲咯啉和/或苯并[ α]] azulenone产品的比例不同。选择性主要由α-取代控制,也可能受联苯环上的取代基影响。此外,对于α-苯甲酰基和磺酰基取代的底物,观察到对于环加成的芳族取代具有高化学选择性。但是除了菲咯啉之外,这些反应还产生芳族酮和/或1,2-二酮,这是从重氮前体中获得的空前产物。报告中给出了机械原理。