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Synfacts 2014; 10(1): 0055
DOI: 10.1055/s-0033-1340454
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Homologation of α-Keto Esters with α-Diazo Esters

Contributor(s):
Hisashi Yamamoto
,
Yusuke Ano
Li W, Liu X, Tan F, Hao X, Zheng J, Lin L, Feng X * Sichuan University, Chengdu, P. R. of China
Catalytic Asymmetric Homologation of α-Ketoesters with α-Diazoesters: Synthesis of Succinate Derivatives with Chiral Quaternary Centers.

Angew. Chem. Int. Ed. 2013;
52: 10883-10886
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Publication History

Publication Date:
13 December 2013 (online)

 
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Key words

diazo esters - α-keto esters - yttrium

Significance

The Lewis acid catalyzed homologation of carbonyl compounds with diazo compounds can realize synthetically useful carbon chain extension. The authors achieve the asymmetric homologation of acyclic α-keto esters with α-diazo esters by using chiral N,N′-dioxide-yttrium(III) complexes. Both aryl- and alkyl-substituted α-keto esters are applicable, providing the corresponding succinate derivatives in good yields and enantioselectivities.


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Comment

The use of bulky adamantyl α-diazo esters can suppress the formation of undesired by-products. Steric hindrance on the 2,6-positions of the phenyl ring in the ligand is also essential to improve both enantioselectivity and reactivity. The attack of α-diazo ester occurs from re-face of the coordinating α-keto ester preferably due to the obstruction of si-face by the aryl group in the N,N′-dioxide ligand.


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