No base is required for the Mg(II)-catalyzed conjugate addition of nitromethane to α′-hydroxy enones in the presence of molecular sieves. Good enantioselectivities are attained using 3 or 4 Å MS and about 10 mol % of Mg(OTf)2-chiral bisoxazoline complexes. Elaboration of the adducts through oxidative cleavage of the ketol moiety provides an entry to enantioenriched γ-nitro carboxylic acids, while a
在
分子筛存在下,Mg(II)催化的
硝基甲烷与α'-羟基烯酮的共轭加成反应不需要碱。使用3或4ÅMS和约10 mol%的Mg(OTf)2-手性双
恶唑啉配合物可获得良好的对映选择性。通过酮醇部分的氧化裂解来精制加合物,可提供对映体富集的γ-硝基
羧酸,而依次进行的羰基还原
-二醇氧化可产生相应的醛。