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Homologations and chain extensions

Name Reactions


Arndt-Eistert Synthesis


Kowalski Ester Homologation


Recent Literature


The reaction of β-keto esters with CF3CO2ZnCH2I provided the corresponding chain-extended products in moderate to good yields. α-Substituted acyclic β-keto esters reacted less efficiently than cyclic β-keto esters or simple β-keto esters.
S. Xue, Y.-K. Liu, L.-Z. Li, Q.-X. Guo, J. Org. Chem., 2005, 70, 8245-8247.


A mild, green, and convenient one-pot carbon-chain extension of carboxylic acids with the assistance of microwaves and lithium chloride avoids the use of corrosive reagents, is tremendously faster than previously methods, and was free of configurational isomerization. Notably, LiCl played a dual role in the Krapcho decarboxylation and subsequent ester hydrolysis under neutral conditions.
C. Wang, J. Su, Y. Li, S. Gao, X. Huo, B. Yi, G. Zhao, Synlett, 2023, 34, 1033-1036.


S. Xue, Y.-K. Liu, L.-Z. Li, Q.-X. Guo, J. Org. Chem., 2005, 70, 8245-8247.


The conversion of β-keto esters into β-methylated and phenylated γ-keto esters can be achieved through treatment with zinc carbenoids derived­ from 1,1-diiodoethane and diiodotoluene, respectively.
W. Lin, R. J. McGinness, E. C. Wilson, C. K. Zercher, Synthesis, 2007, 2404-2408.