在汞灯下由3-碘黄酮生成乙烯基自由基,并且与五元杂芳烃发生串联环化反应,需要两个连续的CC键形成,以合成苯并[ e ] chromeno [2,3 - g ]吲哚-13(1 H))-一阶导数。串联环化反应在乙腈中进行,没有任何添加剂,例如过渡金属,配体和氧化剂,在温和且环境友好的反应条件下,以高收率产生了各种各样的新型多环x吨酮骨架。
基于 Stork-Danheiser 反应,开发了一种以收敛方式获取黄酮的新方法。通过这种方法,4-甲氧基香豆素可以在低温(-78 °C 至 -40 °C)下与有机锂反应,然后进行酸性处理,得到所需的黄酮,产率为 18-86%。该方法具有无过渡金属条件、起始原料易得、操作简单等特点。当需要快速生成 B 环黄酮衍生物时,它特别有效。
Rh-Catalyzed aldehydic C–H alkynylation and annulation
作者:Maddali L. N. Rao、Boddu S. Ramakrishna
DOI:10.1039/c9ob02670c
日期:——
aldehydic C-Hbond alkynylation and annulation for the in situ synthesis of chromones and aurones are described. It involves the sequential aldehydeC-Hbond alkynylation of salicylaldehyde with in situ generated 1-bromoalkyne from 1,1-dibromoalkene followed by annulation. This protocol shows good functional group tolerance including aryl, alkenyl, alkyl and heteroaryl-1,1-dibromoalkenes. The steric/electronic
The easily available and efficient catalyst containing a benzimidazolium ligand and PdCl2(PPh3)(2) demonstrated excellent catalytic activity to construct the flavones and aurones, respectively. This reaction can be operated under mild conditions, affording the desired products in moderate to good yields. This protocol was used to prepare the flavones and aurones by a slight modification of amines. (C) 2013 Elsevier Ltd. All rights reserved.