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A chiral-at-metal asymmetric catalyzed vinylogous Michael addition of ortho-methyl aromatic nitro compounds for isoxazole derivative synthesis†
Yu Du,Qiang Kang
Organic Chemistry Frontiers Pub Date : 06/20/2019 00:00:00 , DOI:10.1039/C9QO00676A
Abstract

ortho-Alkyl aromatic nitro compounds as vinylogous nucleophiles in catalytic asymmetric synthesis have rarely been reported. Herein an asymmetric vinylogous Michael addition of 5-methyl 4-nitroisoxazoles with α,β-unsaturated 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium(III) complex has been developed. The corresponding adducts were obtained in good yields (80–96%) with excellent enantioselectivities (up to 97%). The reaction can be conducted on a gram scale with a low catalyst loading (0.25 mol%) without impacting its efficiency.

Graphical abstract: A chiral-at-metal asymmetric catalyzed vinylogous Michael addition of ortho-methyl aromatic nitro compounds for isoxazole derivative synthesis
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