Acyclic imides. A general method of N-acylation of amides

Many methods of monoacylation of primary amides were studied; one, the sulphuric acid-catalysed reaction of amides with anhydrides at 100°, was found to be very general. Several new acyclic imides were synthesised, including compounds as diverse as N-acetylvaleramide, N-valeryl-4-methylvaleramide, and 3α-acetoxy-N-acetyl-cholanamide. In two cases symmetrical imides related to the anhydride used were identified as minor by-products of the synthesis of mixed imides.