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Synfacts 2015; 11(1): 0047
DOI: 10.1055/s-0034-1379753
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Isomerization of Allylrhodium Intermediates During Allylations of Imines

Contributor(s):
Hisashi Yamamoto
,
Biplab Maji
Hepburn HB, Lam HW * University of Edinburgh and University of Nottingham, UK
The Isomerization of Allylrhodium Intermediates in the Rhodium-Catalyzed Nucleophilic Allylation of Cyclic Imines.

Angew. Chem. Int. Ed. 2014;
53: 11605-11610
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Further Information

Publication History

Publication Date:
15 December 2014 (online)

 
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Key words

allylation - allylrhodium - cyclic imines

Significance

The authors present a 1,4-rhodium(I) migration of allylrhodium intermediates which then react with cyclic imines to yield the allylation product with three stereochemical elements with high selectivity. Using a chiral diene–rhodium catalyst the reaction can be performed enantioselectively. The significance of this work is the generation of stereochemically more complex products from simple starting material through rhodium(I)-catalyzed isomerization processes.


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Comment

The reaction is favored in combination of two factors: 1) the steric hindrance of the initially formed allylrhodium species, and 2) the reactivity of the imine such that normal allylation is disfavored. Through the deuterium-labeling experiments it is proposed that the 1,4-rhodium(I) migration (3a → 3b) occurs by a C–H oxidative addition–reductive elimination sequence via intermediate I.


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