Keten. Part IV. The addition of dimethylketen to some 9-substituted acridines
The reaction of dimethylketen with 9-methlacridine gives open-chain and cyclic adducts composed of one molecule of the heterocyclic base combined with two molecules of dimethylketen. The structures of these compounds have been elucidated. A similar reaction is observed with 9-ethylacridine, but 9-phenylacridine forms only the open-chain adduct. The reactions of these adducts have been investigated, and a mechanism proposed for the migration of an acyl group during reduction with lithium aluminium hydride. The mechanism of formation of keten-ON-acetals by methanolysis of the adducts or their dihydro-derivatives is discussed. The n.m.r. spectra of the keten-ON-acetals show evidence of restricted rotation about a C–N bond.