7-Azabicyclo 2.2. l hepta-2,5-dienes

The structure of the product obtained by the silver(I) ion catalyzed ring expansion of anti-1-chloro-2,3-benzo-7-azabicyclo[2.2.l]hepta-2,5-diene, formulated tentatively as 1-methoxy-l/f-1-benzazepine,140 has been shown to be 2-methoxy-6,7-benzo-l-azabicyclo[3.2.0]hept-3-ene... 

Nitrogen-Bridged Six-Membered Ring Systems 7-Azabicyclo[2.2.l]hepta-2,5-dienes, Naphthalen-l,4-imines, and Anthracen-9,10-imines L. J. Kricka and J. M. Vernon, Adv. Heterocycl. Chem., 1974,16, 87-122. 

Azabicyclo[2.2.l]hepta-2,5-dienes, 16, 87 1-Azabicyclo[3.1.0]hexanes and analogs... 

Both 7-oxa- and 7-azabicyclo[2.2.l]hepta-2,5-dienes photoisomerize to the corresponding 3-heteraquadricyclanes While the oxygen heterocycles are usually stable enough to be... 

Chemistry of 7-azabicyclo[2.2.1]hepta-2,5-dienes, 7-azabicyclo[2.2.1]hept-2-enes and 7-azabicyclo[2.2.1]heptanes , Chen, Z. and Trudell, M. L.,... 

Labile N-nitrosamines. A soln. of NOCl in CCI4 added at -10 to -15° to a mixture of 2,3-benzo-7-azabicyclo [2.2.1] hepta-2,5-diene and Na-acetate in the same solvent, and stirring continued 5 min. at -10° - 7-nitroso-2,3-benzo-7-azabicyclo[2.2.1]hepta-2,5-diene. Y 44%. — The stable 7-nitroso-2,3-benzo-7-azabicyclo [2.2.1] hept-2-ene is similarly obtained in 83% yield. L. A. Carpino and D. E. Barr, J. Org. Chem. 31, 764 (1966). 

A solution of dimethyl 3-acetyl-3-azatetracyclo[3.2.0.02-7.04 6]heptane-l,5-dicarboxylate (2, R1 = Ac R = H), formed by the photolysis (14 h 125-W Hg lamp under N2) of dimethyl 7-acetyl-7-azabicyclo-[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (1 R1 = Ac, R2 = H 1 g, 4mmol) in Et20 (400 mL) at — 40 C, was evaporated to dryness under reduced pressure. The residue (0.7 g, 2.8 mmol) was dissolved in CHC1, and the solution heated under reflux for 1 h. Evaporation of the solvent yielded the crude product which was purified by column chromatography (silica gel, C,H2C12). The yellow fractions were collected and, after removal of the solvent, the residual oil was distilled in a sublimation apparatus to give 3 (R1 = Ac R2 = H) as a yellow oil yield 0.8 g (80%) bp 50 60 C/5 x 10 4 Torr. 

Recently, a new reactivity index has been proposed (80H(14)1717> which predicts accurately the site selectivity of photocyclization of substituted cycloheptatrienes to their bicyclic valence tautomers. Unfortunately, application of the method to substituted lH-azepines is far less successful. For example, for 2-methyl-l-methoxycarbonyl-lH-azepine (37 R = 2-Me) AGrs values for C-2—C-5 and C-4—C-7 cyclization are calculated as 0.093 and 0.040 kJ mol-1, respectively, i.e. predicting the 1-methyl isomer (39) as the major product. Experimentally, however, the reverse is true, the yields being 93.5% for 3-methyl (38 R = Me) and 6.5% for 1-methyl (39 R = Me). The corresponding photoinduced valence isomerizations of 1-benzazepines to 3,4-benz-2-azabicyclo[3.2.0]hepta-3,6-dienes (38a) have been recorded (80JOC462). These isomerizations have also been achieved thermally in the presence of silver ion (80TL3403). 

---