Liu RH, Chai GL, Wang X, Deng HY, Chang J. Chiral-Boron-Complex-Catalyzed Asymmetric [3 + 2] Cycloaddition of β-Trifluoromethyl α,β-Unsaturated Ketones with
N,N'-Cyclic Azomethine Imines.
J Org Chem 2023;
88:16566-16580. [PMID:
37967281 DOI:
10.1021/acs.joc.3c02106]
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Abstract
The (R)-3,3'-(3,5-(CF3)2-C6H3)2-BINOL-boron-complex-catalyzed asymmetric 1,3-dipolar cycloaddition of β-trifluoromethyl α,β-unsaturated ketone with N,N'-cyclic azomethine imines was developed to afford N,N'-bicyclic pyrazolidine derivatives bearing a stereogenic carbon center containing CF3 motifs in high yields with excellent diastereo- and enantioselectivities (up to >20:1 dr, and >99% ee). This catalytic system features mild reaction conditions, high efficiency, and a broad substrate scope.
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