Asymmetric synthesis of pyrano[2,3-c]pyrazoles via a cascade reaction between Morita–Baylis–Hillman acetates of nitroalkenes and pyrazolones
作者:Jin Xie、Feng Sha、Xin-Yan Wu
DOI:10.1016/j.tet.2016.05.033
日期:2016.7
The first organocatalytic enantioselective cascade reaction of Morita–Baylis–Hillman acetates of nitroalkenes with pyrazolones has been developed. With 20 mol % of chiral tertiary-amine squaramide, 1,4,5,6-tetrahydropyrano[2,3-c]pyrazoles were afforded in moderate yields (up to 71%) with excellent stereoselectivities (up to>99:1 dr and up to 98% ee).
已经开发出Morita-Baylis-Hillman的硝基烯烃乙酸酯与吡唑啉酮的第一个有机催化对映选择性级联反应。有了20 mol%的手性叔胺方酸酰胺,就可以以中等收率(高达71%)提供1,4,5,6-四氢吡喃并[2,3-c]吡唑类化合物,且具有优异的立体选择性(高达> 99:1 dr以及高达98%的ee)。