Acyl iodides in organic synthesis. Reactions with morpholine, piperidine, and N-hydrocarbylpiperidines

Acyl iodides RCOI (R = Me, Ph) reacted with morpholine and piperidine to give the corresponding N-acyl derivatives and morpholine or piperidine hydroiodides. Reactions of acyl iodides with N-methyl- and N-ethylpiperidines involved cleavage of the exocyclic R-N bond with formation of N-acylpiperidine and alkyl iodide and were accompanied (to insignificant extent) by cleavage of the endocyclic N-C bond, leading to N-alkyl-N-(5-iodopentyl)acylamides. In the reaction of acetyl iodide with N-phenylpiperidine, the main process was cleavage of just endocyclic N-C bond to produce N-(5-iodopentyl)-N-phenylacetamide and its dehydroiodination product, N-(pent-4-en-1-yl)-N-phenylacetamide. Analogous reaction with benzoyl iodide afforded N-(5-iodopentyl)-N-phenylbenzamide in a poor yield.