UNSATURATED HETEROCYCLIC SYSTEMS .52. A GENERAL SYNTHETIC ENTRY TO DERIVATIVES OF 1H-AZEPINE

A general synthesis of 1H-azepines has been realized, which consists in the electrophilic addition of iodine isocyanate to easily accessible 1,4-dihydrobenzene derivatives. Cyclization of the resulting iodoisocyanates or their derived carbamates with various bases gives rise to unsaturated aziridines which can be brominated-dehydrobrominated to produce the desired 1H-azepines. This preparative route has been found to be versatile and to allow the ready introduction of alkyl groups on the central ring as well as a variety of substituents on nitrogen. The effect of annelation at the 2,7 positions of a 1H-azepine has been studied. The presence of a tetramethylene bridge is not sufficient to constrain the molecule into the tautomeric azanorcaradiene form; however, a trimethylene bridge serves well in this capacity. The various spectral properties of these cyclic 8π-electron heterocycles are correlated. The preparation of iron carbonyl complexes of these azepines and their fluxional nmr behavior are described. © 1969, American Chemical Society. All rights reserved.