esters are versatile intermediates for the synthesis of many biologically active natural products. Here we report a new intramolecular cyclopropanation reaction of unsaturated beta-keto esters. In the presence of I(2), Et(3)N, and Lewis acids such as Mg(ClO(4))(2) and Yb(OTf)(3), beta-keto esters 1 bearing various olefin substituents were transformed to fused cyclopropanes 2 in a highly stereospecific manner
[反应:见正文]熔融的
环丙烷β-
酮酸酯是用于合成许多具有
生物活性的
天然产物的通用中间体。在这里,我们报告不饱和的β-
酮酯的新的分子内
环丙烷化反应。在I(2),Et(3)N和Lewis酸(例如Mg(ClO(4))(2)和Yb(OTf)(3))的存在下,对带有各种烯烃取代基的β-
酮酯1进行了转化以高度立体定向的方式,以中等至良好的产率合成稠合的
环丙烷2。还研究了反应机理。