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Synfacts 2018; 14(02): 0149
DOI: 10.1055/s-0036-1591015
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Coupling of Boronic Acids, 1,3-Enynes and Cyclic Imines

Rezensent(en):
Mark Lautens
,
Tamara Beisel
Callingham M. Partridge BM. Lewis W. Lam HW. * University of Nottingham and University of Sheffield, UK
Enantioselective Rhodium-Catalyzed Coupling of Arylboronic Acids, 1,3-Enynes, and Imines by Alkenyl-to-Allyl 1,4-Rhodium(I) Migration.

Angew. Chem. Int. Ed. 2017;
56: 16352-16356
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Publikationsverlauf

Publikationsdatum:
18. Januar 2018 (online)

 
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Key words

rhodium catalysis - enantioselective nucleophilic allylation - 1,4-rhodium(I) migration - three-component coupling

Significance

The authors describe a rhodium-catalyzed highly stereoselective coupling of arylboronic acids, 1,3-enynes and cyclic imines. The key step is an alkenyl-to-allyl 1,4-Rh(I) migration, which leads to enantioselective allylation with the cyclic imine. Given the number of alternative pathways, the chemoselectivity of this method is notable.


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Comment

Deuterium-labeling experiments suggest that the 1,4-Rh(I) migration occurs by C–H oxidative addition to give a Rh(III) hydride, followed by C–H reductive elimination. Use of ZnCl2 gave more consistent results. The authors suggest an acceleration of the allylation by Lewis acid activation or improvement of catalyst turnover.


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