A Convenient Mild Two Step Conversion of Imines to Secondary and Tertiary Amides

Treatment of DELTA-2-1,2,4-oxadiazolines (4,5-dihydro-1,2,4-oxadiazoles), readily formed by cycloaddition of nitrile oxides to imines, with potassium tert-butoxide leads to cycloreversion of the resulting anions to give a nitrile and the amide anion which can be hydrolysed or alkylated to provide a mild nonoxidising method for the synthesis of secondary or tertiary amides. Deprotonation of the 1,4,2-dioxazoles available from aromatic aldehydes and nitrile oxides similarly affords carboxylic acids and methyl esters.