A new approach to construct a fused 2-ylidene chromene ring: highly regioselective synthesis of novel chromeno quinoxalines
作者:K. Shiva Kumar、D. Rambabu、Bagineni Prasad、Mohammad Mujahid、G. Rama Krishna、M. V. Basaveswara Rao、C. Malla Reddy、G. R. Vanaja、Arunasree M. Kalle、Manojit Pal
DOI:10.1039/c2ob25416f
日期:——
Regioselective construction of a fused 2-ylidene chromene ring was achieved for the first time by using AlCl3-induced C–C bond formation followed by Pd/C–Cu mediate coupling-cyclization strategy. A number of chromeno[4,3-b]quinoxaline derivatives were prepared by using this strategy. Single crystal X-ray diffraction study of a representative compound e.g. 6-(2,2-dimethylpropylidene)-4-methyl-6H-chromeno[4,3-b]quinoxalin-3-ol confirmed the presence of an exocyclic C–C double bond with Z-geometry. The crystal structure analysis and hydrogen bonding patterns of the same compound along with its structure elaboration via propargylation followed by Sonogashira coupling of the resulting terminal alkyne is presented. A probable mechanism for the formation of 2-ylidene chromene ring is discussed. Some of the compounds synthesized showed anticancer properties when tested in vitro.
首次通过使用AlCl3诱导的C–C键形成以及随后进行Pd/C–Cu介导的耦合-环化策略,成功实现了熔合2-亚烯基色烯环的区域选择性构建。利用该策略合成了一系列色烯[4,3-b]喹啉衍生物。对代表性化合物6-(2,2-二甲基丙烯基)-4-甲基-6H-色烯[4,3-b]喹啉-3-醇的单晶X射线衍射研究证实了具有Z-几何构型的环外C–C双键的存在。还展示了该化合物的晶体结构分析和氢键模式,以及通过炔基化反应后的Sonogashira耦合进行的结构阐明。讨论了2-亚烯基色烯环形成的可能机制。部分合成的化合物在体外测试中显示出抗癌性质。