Li SW, Wan Q, Kang Q. Chiral-at-Metal Rh(III) Complex-Catalyzed Michael Addition of Pyrazolones with α,β-Unsaturated 2-Acyl Imidazoles.
Org Lett 2018;
20:1312-1315. [PMID:
29446638 DOI:
10.1021/acs.orglett.8b00040]
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Abstract
An efficient enantioselective conjugate addition of pyrazolones with α,β-unsaturated 2-acyl imidazoles catalyzed by chiral-at-metal rhodium complex is reported. The corresponding adducts were obtained in good yields (85%-96%) with excellent enantioselectivities (up to >99%). This protocol exhibits extraordinary reactivity, because of the fact that a complex with as little as 0.05 mol % Rh(III) can catalyze the title reaction on a gram-scale with excellent enantioselectivity.
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