Aj. Kiessling et Ck. Mcclure, THE CONVERSION OF AMIDES TO ESTERS WITH MEERWEINS REAGENT - APPLICATION TO THE SYNTHESIS OF A CARFENTANIL PRECURSOR, Synthetic communications, 27(5), 1997, pp. 923-937
An efficient two step transformation of 1 degrees and 2 degrees amides
to methyl and ethyl esters has been developed using trimethyl- and tr
iethyloxonium tetrafluoroborates, and dilute acid. This methodology wa
s applied to 1-benzyl-4-phenylamino-4-piperidinecarboxamide precursor
in the synthesis of carfentanil, to produce the methyl ester in 60% yi
eld and the ethyl ester in 80% yield.