Catalytic Asymmetric Reactions of 4-Substituted Indoles with Nitroethene: A Direct Entry to Ergot Alkaloid Structures
作者:Simone Romanini、Emilio Galletti、Lorenzo Caruana、Andrea Mazzanti、Fahmi Himo、Stefano Santoro、Mariafrancesca Fochi、Luca Bernardi
DOI:10.1002/chem.201502655
日期:2015.12.1
A domino Friedel–Crafts/nitro‐Michael reaction between 4‐substituted indoles and nitroethene is presented. The reaction is catalyzed by BINOL‐derived phosphoric acid catalysts, and delivers the corresponding 3,4‐ring‐fused indoles with very good results in terms of yields and diastereo‐ and enantioselectivities. The tricyclic benzo[cd]indole products bear a nitro group at the right position to serve
提出了 4-取代吲哚和硝基乙烯之间的多米诺弗里德尔-克拉夫茨/硝基-迈克尔反应。该反应由 BINOL 衍生的磷酸催化剂催化,并产生相应的 3,4-环稠合吲哚,在产率以及非对映和对映选择性方面具有非常好的结果。三环苯并[ cd ]吲哚产物在正确的位置带有硝基,可作为麦角生物碱的前体,如从一种加合物正式合成6,7-开麦角碱所证明的那样。DFT 计算表明,反应的结果源于关键硝酸中间体通过亲核加成途径的优先演化,而不是预期的通过质子化的“猝灭”。