UNSATURATED HETEROCYCLIC SYSTEMS .53. THERMOCHEMICAL REACTIONS OF 1H-AZEPINE DERIVATIVES .2. AROMATIZATION AND SIGMATROPIC MIGRATIONS INVOLVING NITROGEN

In contrast to N-carbalkoxy-1H-azepines and their 3- and 4-methyl derivatives which undergo ready dimerization at elevated temperatures, 2-methyl-N-carbomethoxyazepine and a number of disubstituted and annelated congeners are seen to aromatize or rearrange when heated. This behavior is not shared by 2,7-dimethyl-N-carbomethoxyazepine, which is stable at 250°, but decomposes above that temperature; no characterizable products are produced. A mechanistic interpretation of these results derived in part on product analysis and founded to some degree of thermodynamic considerations is advanced. Acid-catalyzed rearrangements of these same azepines are also discussed, since the bond reorganizations noted in this aspect of the work provide parallel mechanistic insight into the structural requirements for the changes which occur. © 1969, American Chemical Society. All rights reserved.