Iridium-catalyzed regiospecific and stereospecific allylic amination for the syntheses of α,β-unsaturated γ-amino esters and the bifurcation of the reaction pathway leading to the formation of oxazolidin-2-ones
作者:Jun Hee Lee、Sang-gi Lee
DOI:10.1039/c3sc50901j
日期:——
A pair of iridium-catalyzed regiospecific and stereospecific reactions of the carbonates of γ-hydroxy α,β-unsaturated esters were developed. The reaction pathways are strongly affected by the choice of amines employed. A diverse range of γ-substituted α,β-unsaturated γ-amino esters were prepared in excellent yields with various amine nucleophiles such as benzylamine, diallylamine, morpholine, aniline and N-methylaniline. Substitution at the γ-position was well tolerated, encompassing alkyl, aryl and heteroaryl substituents. Enantioenriched (E)-α,β-unsaturated γ-amino esters could also be synthesized from the corresponding enantioenriched allylic carbonates with complete chirality transfer. In sharp contrast, a series of 3,4-disubstituted oxazolidin-2-ones were obtained by using allylamine as a nucleophile.
开发了一对铱催化的γ-羟基α,β-不饱和酯的碳酸酯的区域特异性和立体特异性反应。反应途径很大程度上受到所用胺的选择的影响。用各种胺亲核试剂如苄胺、二烯丙基胺、吗啉、苯胺和N-甲基苯胺以优异的产率制备了多种γ-取代的α,β-不饱和γ-氨基酯。 γ-位的取代具有良好的耐受性,包括烷基、芳基和杂芳基取代基。对映体富集的(E)-α,β-不饱和γ-氨基酯也可以从相应的对映体富集的烯丙碳酸酯合成,具有完全的手性转移。与此形成鲜明对比的是,使用烯丙胺作为亲核试剂得到了一系列3,4-二取代恶唑烷-2-酮。