Transformations of dibenzo(γ-oxopiperidino)aza-14-crowns-4 upon acylation. Molecular structure of dibenzo-16-crown-3

The result of acylation of dibenzoaza-14-crowns-4 containing a 4-oxopiperidine fragment with acetic anhydride depends on the substituent on the nitrogen atom. The NH-substrates initially undergo acylation at the piperidine nitrogen atom, followed by enolization and O-acylation. The acylation of N-methyl derivatives is accompanied by cleavage of the piperidine ring at the C-N bond with formation of acetylamino-substituted dibenzo-16-crowns-3. The structure of the latter was determined by X-ray analysis. © 2008 MAIK Nauka.