Bis(oxazoline)-Cu(II) Catalyzed Highly Enantioselective Asymmetric 1,4-Conjugate Addition of In Situ Generated
Jing-Jing Zhai1, Yang-Jie Mao1, Jin Li1
1State Key Laboratory of Green Chemical Synthesis and Conversion, Key Laboratory of Green Pesticides and Cleaner Production Technology of Zhejiang Province, Catalytic Hydrogenation Research Center, Zhejiang University of Technology, Hangzhou 310014, P. R. China.
Abstract:
A chiral bis(oxazoline)-Cu(II) complex-catalyzed asymmetric 1,4-conjugate addition of β-ketoesters to in situ generated 3-indole imine methides (3-IIMs) has been developed. The synergistic Lewis acid/Brønsted acid catalytic system enables the efficient construction of enantioenriched 3-indolyl derivatives featuring congested adjacent quaternary and tertiary stereocenters with excellent efficiency (up to >20:1 dr, 99% ee). This work not only provides a complementary and robust alternative to existing organocatalytic strategies for accessing chiral 3-indolyl scaffolds but also significantly enriches the synthetic chemistry of 3-indolylmethanols by expanding their asymmetric transformation repertoires.
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