Krapcho decarboxylation

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 basically a SN2-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 which 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

  1. ^ Flynn, D (1992). "Use of atom-transfer radical cyclizations as an efficient entry into a new "serotonergic" azanoradamantane". Tetrahedron Letters 33 (48): 7283. doi:10.1016/S0040-4039(00)60166-1. 
  2. ^ Krapcho, A. Paul; Weimaster, J. F.; Eldridge, J. M.; Jahngen, E. G. E.; Lovey, A. J.; Stephens, W. P. (1978). "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: 138. doi:10.1021/jo00395a032. 
  3. ^ Krapcho, A (1974). "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. doi:10.1016/S0040-4039(01)82414-X. 
  4. ^ Krapcho, A (1967). "The decarbethoxylation of geminal dicarbethoxy compounds". Tetrahedron Letters 8 (31): 215. doi:10.1016/S0040-4039(00)90519-7.