Krapcho decarboxylation

Krapcho decarboxylation
Named after	A. Paul Krapcho
Reaction type	Substitution reaction
Identifiers
RSC ontology ID	RXNO:0000507

The Krapcho decarboxylation is the chemical reaction of esters with halide anions. The ester must contain an electron-withdrawing group in the beta position, such as β-ketoesters, malonic esters, α-cyanoesters, or α-sulfonylesters. It works best with methyl esters, since it is an S_N2-reaction at carbon. It is driven by the entropy of the overall reaction, as the byproducts chloromethane and CO₂ are lost as gases. The reaction is a useful synthetic procedure to hydrolyze and decarboxylate malonic esters because it only cleaves one of the ester groups. The alternative way (e.g. basic hydrolysis) destroys both of the ester groups and a subsequent reaction is usually used to regenerate the alkylated ester.^[1]^[2]^[3]^[4]

References

^ Flynn, Daniel L.; Becker, Daniel P.; Nosal, Roger; Zabrowski, Daniel L. (1992-11-24). "Use of atom-transfer radical cyclizations as an efficient entry into a new "serotonergic" azanoradamantane". Tetrahedron Letters. The International Journal for the Rapid Publication of Preliminary. 33 (48): 7283–7286. doi:10.1016/S0040-4039(00)60166-1. ISSN 0040-4039.
^ Krapcho, A. Paul; Weimaster, J. F.; Eldridge, J. M.; Jahngen, E. G. E.; Lovey, A. J.; Stephens, W. P. (1978-01-01). "Synthetic applications and mechanism studies of the decarbalkoxylations of geminal diesters and related systems effected in dimethyl sulfoxide by water and/or by water with added salts". The Journal of Organic Chemistry. 43 (1): 138–147. doi:10.1021/jo00395a032. ISSN 0022-3263.
^ Krapcho, A. Paul; Jahngen, E. G. E.; Lovey, A. J.; Short, Franklin W. (1974-01-01). "Decarbalkoxylations of geminal diesters and β-keto esters in wet dimethyl sulfoxide. Effect of added sodium chloride on the decarbalkoxylation rates of mono- and di-substituted Malonate esters". Tetrahedron Letters. 15 (13): 1091–1094. doi:10.1016/S0040-4039(01)82414-X. ISSN 0040-4039.
^ Krapcho, A. Paul; Glynn, Gary A.; Grenon, Brian J. (1967-01-01). "The decarbethoxylation of geminal dicarbethoxy compounds". Tetrahedron Letters. 8 (3): 215–217. doi:10.1016/S0040-4039(00)90519-7. ISSN 0040-4039. PMID 6037875.

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[1] Flynn, Daniel L.; Becker, Daniel P.; Nosal, Roger; Zabrowski, Daniel L. (1992-11-24). "Use of atom-transfer radical cyclizations as an efficient entry into a new "serotonergic" azanoradamantane". Tetrahedron Letters. The International Journal for the Rapid Publication of Preliminary. 33 (48): 7283–7286. doi:10.1016/S0040-4039(00)60166-1. ISSN 0040-4039.

[2] Krapcho, A. Paul; Weimaster, J. F.; Eldridge, J. M.; Jahngen, E. G. E.; Lovey, A. J.; Stephens, W. P. (1978-01-01). "Synthetic applications and mechanism studies of the decarbalkoxylations of geminal diesters and related systems effected in dimethyl sulfoxide by water and/or by water with added salts". The Journal of Organic Chemistry. 43 (1): 138–147. doi:10.1021/jo00395a032. ISSN 0022-3263.

[3] Krapcho, A. Paul; Jahngen, E. G. E.; Lovey, A. J.; Short, Franklin W. (1974-01-01). "Decarbalkoxylations of geminal diesters and β-keto esters in wet dimethyl sulfoxide. Effect of added sodium chloride on the decarbalkoxylation rates of mono- and di-substituted Malonate esters". Tetrahedron Letters. 15 (13): 1091–1094. doi:10.1016/S0040-4039(01)82414-X. ISSN 0040-4039.

[4] Krapcho, A. Paul; Glynn, Gary A.; Grenon, Brian J. (1967-01-01). "The decarbethoxylation of geminal dicarbethoxy compounds". Tetrahedron Letters. 8 (3): 215–217. doi:10.1016/S0040-4039(00)90519-7. ISSN 0040-4039. PMID 6037875.

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