Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland.
Org Lett. 2011 Nov 18;13(22):5944-7. doi: 10.1021/ol202244u. Epub 2011 Oct 19.
We report the first efficient enantioselective Friedel-Crafts hydroxyalkylation of pyrroles having one electron-withdrawing group at the α, β or N-positions with alkyl glyoxylates catalyzed by readily available chiral BINOL-Ti(IV) complexes (1-5 mol %). The reaction regioselectively led to the desired pyrrole-hydroxyacetic acid derivatives with good yields (70-96%) and enantiomeric excesses up to 96%, and is applicable in multigram scale with low loading of the catalyst (1 mol %).
我们报告了首例通过 readily available chiral BINOL-Ti(IV) complexes (1-5 mol %) 催化的具有一个吸电子基团在 α, β 或 N-位的吡咯的 Friedel-Crafts 对映选择性羟烷基化反应。该反应具有很好的区域选择性，得到了所需的吡咯-羟乙酸衍生物，产率高达 70-96%，对映过量高达 96%，并且在低催化剂负载量（1 mol %）下也适用于大规模反应。
