Co-reporter:Yong Wang, Xin Wen, Xin Cui, Lukasz Wojtas, and X. Peter Zhang
Journal of the American Chemical Society 2017 Volume 139(Issue 3) pp:1049-1052
Publication Date(Web):January 4, 2017
DOI:10.1021/jacs.6b11336
Donor-substituted diazo reagents, generated in situ from sulfonyl hydrazones in the presence of base, can serve as suitable radical precursors for Co(II)-based metalloradical catalysis (MRC). The cobalt(II) complex of D2-symmetric chiral porphyrin [Co(3,5-DitBu-Xu(2′-Naph)Phyrin)] is an efficient metalloradical catalyst that is capable of activating different N-arylsulfonyl hydrazones for asymmetric radical cyclopropanation of a broad range of alkenes, affording the corresponding cyclopropanes in high yields with effective control of both diastereo- and enantioselectivity. This Co(II)-based metalloradical system represents the first catalytic protocol that can effectively utilize donor-type diazo reagents for asymmetric olefin cyclopropanation.
Co-reporter:Xue Xu;Yong Wang;Xin Cui;Lukasz Wojtas
Chemical Science (2010-Present) 2017 vol. 8(Issue 6) pp:4347-4351
Publication Date(Web):2017/05/30
DOI:10.1039/C7SC00658F
For the first time, α-formyldiazoacetates have been successfully applied for the asymmetric cyclopropanation of alkenes via Co(II)-based metalloradical catalysis. The cobalt(II) complex of the D2-symmetric chiral amidoporphyrin [Co(3,5-DitBu-ChenPhyrin)] is an effective metalloradical catalyst that can activate α-formyldiazoacetates to cyclopropanate both aromatic and aliphatic olefins with varied electronic properties, affording the synthetically useful 1,1-cyclopropaneformylesters in high yields with both high diastereo- and enantioselectivity.
Co-reporter:Qiong-Jie Liu;Dr. Lijia Wang;Qi-Kai Kang;Dr. X. Peter Zhang;Dr. Yong Tang
Angewandte Chemie 2016 Volume 128( Issue 32) pp:9366-9369
Publication Date(Web):
DOI:10.1002/ange.201603911
Abstract
Facile and effective access for the asymmetric construction of the useful and important skeleton of the bicyclic N,O-acetals is described. CuII/SaBOX could catalyze the reaction of β,γ-unsaturated α-ketoesters with cyclic enamines efficiently, thus affording the desired products in excellent yields with excellent stereoselectivities (21 examples; up to 99 % yields; up to >95:5 d.r.; and 95–99 % ee). This reaction can be well performed on gram scale, even with only 1 mol % catalyst loading. The single-crystal structures of the copper complexes lead to a good understanding of the stereo-synergistic effects of the sidearm.
Co-reporter:Qiong-Jie Liu;Dr. Lijia Wang;Qi-Kai Kang;Dr. X. Peter Zhang;Dr. Yong Tang
Angewandte Chemie International Edition 2016 Volume 55( Issue 32) pp:9220-9223
Publication Date(Web):
DOI:10.1002/anie.201603911
Abstract
Facile and effective access for the asymmetric construction of the useful and important skeleton of the bicyclic N,O-acetals is described. CuII/SaBOX could catalyze the reaction of β,γ-unsaturated α-ketoesters with cyclic enamines efficiently, thus affording the desired products in excellent yields with excellent stereoselectivities (21 examples; up to 99 % yields; up to >95:5 d.r.; and 95–99 % ee). This reaction can be well performed on gram scale, even with only 1 mol % catalyst loading. The single-crystal structures of the copper complexes lead to a good understanding of the stereo-synergistic effects of the sidearm.
Co-reporter:Hongjian Lu, Kai Lang, Huiling Jiang, Lukasz Wojtas and X. Peter Zhang
Chemical Science (2010-Present) 2016 - vol. 7(Issue 12) pp:NaN6939-6939
Publication Date(Web):2016/07/28
DOI:10.1039/C6SC02231F
Co(II)-based metalloradical catalysis (MRC) proves effective for intramolecular 1,5-C–H amination of sulfamoyl azides under neutral and nonoxidative conditions, providing a straightforward approach to access strained 5-membered cyclic sulfamides with nitrogen gas as the only byproduct. The metalloradical amination system is applicable to different types of C(sp3)–H bonds and has a high degree of functional group tolerance. Additional features of the Co(II)-catalyzed 1,5-C–H amination include excellent chemoselectivity toward allylic and propargylic C–H bonds. The unique reactivity and selectivity profile of the Co(II)-catalyzed 1,5-C–H amination is attributed to the underlying radical mechanism of MRC.
Co-reporter:Xue Xu, Yong Wang, Xin Cui, Lukasz Wojtas and X. Peter Zhang
Chemical Science (2010-Present) 2017 - vol. 8(Issue 6) pp:NaN4351-4351
Publication Date(Web):2017/03/31
DOI:10.1039/C7SC00658F
For the first time, α-formyldiazoacetates have been successfully applied for the asymmetric cyclopropanation of alkenes via Co(II)-based metalloradical catalysis. The cobalt(II) complex of the D2-symmetric chiral amidoporphyrin [Co(3,5-DitBu-ChenPhyrin)] is an effective metalloradical catalyst that can activate α-formyldiazoacetates to cyclopropanate both aromatic and aliphatic olefins with varied electronic properties, affording the synthetically useful 1,1-cyclopropaneformylesters in high yields with both high diastereo- and enantioselectivity.
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