Chiral Brønsted Acid from Chiral Phosphoric Acid Boron Complex and Water: Asymmetric Reduction of Indoles
作者:Kai Yang、Yixian Lou、Chenglan Wang、Liang‐Wen Qi、Tongchang Fang、Feng Zhang、Hetao Xu、Lu Zhou、Wangyang Li、Guan Zhang、Peiyuan Yu、Qiuling Song
DOI:10.1002/anie.201913656
日期:2020.2.17
A new chiral Brønsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This "designer acid catalyst", which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities
由手性磷酸硼(CPAB)配合物和水原位生成的新手性布朗斯台德酸已成功地用于不对称吲哚还原。如DFT计算所建议的,这种“设计酸催化剂”比TsOH酸性更强,可实现C2-芳基取代的N-未保护的吲哚空前的直接不对称还原,并具有良好的对映选择性,并具有宽泛的官能团耐受性。DFT计算和机理实验表明该反应经历了C3质子化和氢化物转移过程。此外,庞大的C 2-烷基取代的N-未保护的吲哚也适用于该体系。