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Bargellini condensation of coumarins. Expeditious route to o-carboxyvinylphenoxyisobutyric acids and application to the synthesis of sesquiterpenes helianane, heliannuol A and heliannuol C
作者:Bidyut Biswas、Prabir K. Sen、Ramanathapuram V. Venkateswaran
DOI:10.1016/j.tet.2007.09.006
日期:2007.11
The direct Bargellini condensation of coumarins involving reaction with chloroform and acetone in the presence of aqueous sodium hydroxide furnished o-carboxyvinylphenoxyisobutyric acids in good yields. The utility of this new useful protocol was demonstrated by the transformation of the three diesters 9b, 9f and 9g to the sesquiterpenes helianane 4, heliannuol A 2 and heliannuol C 3, respectively
香豆素的Bargellini直接缩合反应涉及在氢氧化钠水溶液存在下与氯仿和丙酮反应,从而以良好的收率提供了邻羧基羧乙烯基苯氧基异丁酸。通过将三个二酯9b,9f和9g分别转化为倍半萜烯helaneane 4,heliannuol A 2和heliannuol C 3,证明了该新有用方案的实用性。
Synthesis of heliannuols A and K, allelochemicals from cultivar sunflowers and the marine metabolite helianane, unusual sesquiterpenes containing a benzoxocane ring system
作者:Subrata Ghosh、Kazi Tuhina、Dipal R. Bhowmik、Ramanathapuram V. Venkateswaran
DOI:10.1016/j.tet.2006.11.014
日期:2007.1
Synthesis of the allelochemicals heliannuols A and K, and the sesquiterpene helianane is described. A regioselective cleavage of a benzo-fused oxabicyclo(5.1.0)octane system under hydrogenation as well as radical induced condition was developed to generate the basic benzoxocane ring system of these unusual sesquiterpenes.