Synthesis of N-t-Butyl Benzamides

Abstract

N-t-butyl benzamides have been prepared by the reaction of t-butyl amine with the corresponding aroyl chloride in a solution of 10% aqueous sodium hydroxide¹ and by the Ritter reaction using isobutylene and the appropriate aryl cyanide.² We have found that N-t-butyl benzamides can be prepared in excellent yield by the reaction of one equivalent of aroyl acid chloride³ with an ethereal solution of one equivalent of t-butyl amine and one equivalent of triethyl amine. The role of the triethyl amine is that of a base to scavenge the one equivalent of hydrochloric acid produced in the reaction. Work-up of the reaction mixture consists simply of filtering the reaction mixture to remove the solid triethylammonium chloride and in vacuo removal of ether to afford the desired amide. Purification of the crude N-t-butyl benzamide may then be affected by either crystallization (ether-pentane mixtures) or by sublimation. The general reaction is given below in equation I, and representative yields are indicated in Table I. The general reaction procedure and the specific procedure for the preparation of N-t-butyl benzamide are included in the following text.