Chiral Brønsted Base-Promoted Nitroalkane Alkylation: Enantioselective Synthesis of <i>sec</i>-Alkyl-3-Substituted Indoles
作者:Mark C. Dobish、Jeffrey N. Johnston
DOI:10.1021/ol1025712
日期:2010.12.17
A Brønsted base-catalyzed reaction of nitroalkanes with alkyl electrophiles provides indole heterocycles substituted at C3 bearing a sec-alkyl group with good enantioselectivity (up to 90% ee). Denitration by hydrogenolysis provides a product with equally high ee. An indolenine intermediate is implicated in the addition step, and surprisingly, water cosolvent was found to have a beneficial effect in
硝基烷烃与烷基亲电试剂的布朗斯台德碱催化反应提供了在 C3 处取代的吲哚杂环,带有一个具有良好对映选择性(高达 90% ee)的仲烷基。通过氢解脱硝提供具有同样高 ee 的产品。在添加步骤中涉及吲哚中间体,令人惊讶的是,发现水共溶剂在该步骤中具有有益作用,导致使用 PBAM(一种双(脒)手性非外消旋碱)消除/对映选择性添加的一锅法。