42858-53-7Relevant academic research and scientific papers
Double Activation Catalysis for α′-Alkylidene Cyclic Enones with Chiral Amines and Thiols
Wang, Zhou-Xiang,Zhou, Zhi,Xiao, Wei,Ouyang, Qin,Du, Wei,Chen, Ying-Chun
, p. 10678 - 10682 (2017)
Cooperative catalysis has contributed greatly to the progress of asymmetric synthesis. However, double-activation catalysis has been less explored, especially for covalently tethered species. Here, we present a double-activation strategy for α′-alkylidene cyclic enone substrates that uses a chiral primary amine and 2-mercaptobenzoic acid to promote regio- and chemoselective addition to generate the complex interrupted iminium ion species. Significantly enhanced reactivity and enantioselectivity were observed for β-regioselective Michael addition and Friedel–Crafts alkylation with malononitriles and indoles, respectively, which produced a spectrum of chiral cyclic adducts with an exo-alkylidene group. Moreover, a HRMS study detected a few key covalently tethered intermediates among the substrates and catalysts, which helped elucidate the catalytic mechanism.
