Preparation of alpha -ketocarboxylic acid N-tert.-butylamides

摘要

A process for the preparation of an alpha -ketocarboxylic acid N-tert.-butylamide of the formula R-CO-CO-NH-C(CH3)3 in which R is an aliphatic radical with up to 8 carbon atoms, a cycloalkyl radical with 3 to 6 carbon atoms, a phenyl or naphthyl radical or a heterocyclic radical, comprising reacting an acyl cyanide of the formula R-CO-CN with tert.-butyl methyl ether of the formula (CH3)3C-O-CH3 at a temperature between about 0 DEG and 80 DEG C. in the presence of an acid which is capable of activating the ether of formula (III) under the reaction conditions to give a tert.-butyl carbonium ion, and then hydrolyzing the reaction mixture. Advantageously the acyl cyanide is pivaloyl cyanide or benzoyl cyanide and is reacted with an approximately equimolar amount of the ether in the presence of about 1.1 to 1.5 times the molar amount of concentrated sulphuric acid as the activating acid. The products are useful as intermediates in the synthesis of known herbicides.