The diastereoselective electrochemical carboxylation of chiral N-(2-bromoacyl)oxazolidin-2-ones has been studied. This reaction was carried out by cathodic reduction of the C-Br bond, in the presence of carbon dioxide, followed by treatment with diazomethane. The yields and the diastereomeric ratio of the two epimeric alkylmalonic acid derivatives are strongly affected by various factors: solvent-supporting electrolyte system, temperature, electrode material, electrolysis conditions, oxazolidinone moiety. The higher yields (88%) were obtained starting from N-(2-bromopropionyl)4R-phenyloxazolidin-2-one la, but with poor diastereoselectivity (61:39). The two epimers were easily separated by flash chromatography. The best results were achieved using a different chiral auxiliary: Oppolzer's camphor sultam. Starting from 1j a good yield in carboxylated product was obtained (80%) with excellent diastereoselectivity (98:2). These chiral alkylmalonic acid derivatives are valuable building blocks in the synthesis of molecules with biological activity and of chiral propane-1,3-diols derivatives.

FEROCI M., ORSINI M., PALOMBI L., SOTGIU G, COLAPIETRO M., & INESI A. (2004). Diastereoselective electrochemical carboxylation of chiral ?-bromocarboxylic acid derivatives: an easy access to unsymmetrical alkylmalonic ester derivatives. JOURNAL OF ORGANIC CHEMISTRY, 69(2), 487-494 [10.1021/jo0343836].

Diastereoselective electrochemical carboxylation of chiral ?-bromocarboxylic acid derivatives: an easy access to unsymmetrical alkylmalonic ester derivatives

SOTGIU, Giovanni;
2004

Abstract

The diastereoselective electrochemical carboxylation of chiral N-(2-bromoacyl)oxazolidin-2-ones has been studied. This reaction was carried out by cathodic reduction of the C-Br bond, in the presence of carbon dioxide, followed by treatment with diazomethane. The yields and the diastereomeric ratio of the two epimeric alkylmalonic acid derivatives are strongly affected by various factors: solvent-supporting electrolyte system, temperature, electrode material, electrolysis conditions, oxazolidinone moiety. The higher yields (88%) were obtained starting from N-(2-bromopropionyl)4R-phenyloxazolidin-2-one la, but with poor diastereoselectivity (61:39). The two epimers were easily separated by flash chromatography. The best results were achieved using a different chiral auxiliary: Oppolzer's camphor sultam. Starting from 1j a good yield in carboxylated product was obtained (80%) with excellent diastereoselectivity (98:2). These chiral alkylmalonic acid derivatives are valuable building blocks in the synthesis of molecules with biological activity and of chiral propane-1,3-diols derivatives.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11590/143311
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