N-Cyanoazepines from Cyanonitrene and Aromatic Compounds

Heterocyclic polyfluoro-compounds. Part 40. Preparation of polyfluoroazepines

“…Pyrolysis of 1,2,3,4,5,8, Preparation of Ethyl Hexafluoro-1 H-azepine-1 -carboxylate (4).--Ethyl azidoformate l4 (3.28 g, 28.5 mmol) and hexafluorobenzene (31.75 g, 170.7 mmol), sealed in a Pyrex ampoule (100 cm3) and heated in vacuo a t 90 "C for 72 11, gave nitrogen as a noncondensable gas, material volatile a t room temperature, which was fractionated by trap-to-trap distillation in vacuo to give a mixture of carbon dioxide ancl ethylene (10 mg) , and recovered hexafluorobenzene (30.10 g , 161.8 mmol, 95%). The residue was distilled, in vacuo, to give ethyl hexafluoro-1 H-azepine-l-carboxylate (4) (1.63 g, 6.0 mmol, 21%) (Found: C, 39.5; H, 2.3; F, 41.7; N, 5.4.…”

“…Nitrogen (0.35 g, 12.5 mmol, 95%) was then removed at -196 "C, and cyanogen chloride (0.79 g , 12.8 mmol), acetonitrile (4.70 g), and methylene dichloride (24.06 g) were removed at room temperature in vucuo. The methylene dichloride soluble portion (2.40 g) of the residue (4.25 g) was sublimed in vacuo t o give 1,2,3,4-tetraAuoronaphthalene (1.45 g , 7.25 Thermal Rearrangement of 1,2-(Ethoxycarbony1imino) 2,4,5,6,7, .-Theiminocompound (8) (1.5 g, 4.2 mmol) and toluene (58.1 g), sealed in a Pyrex ampoule (300 cm3) and heated at 155 "C for 60 h, gave, after removal of the solvent in vacuo, a residue (1.3 g) which was distilled a t 75 "C and 0.05 mmHg to give a fraction (0.53 g) shown by g. -32.0 (F-1, 1J1,8I 33 Hz), -40.2 (F-2), -58.8 (F-8),…”

Reaction of methanesulfonyl nitrene with benzene. Attempts to generate sulfonyl nitrenes from sources other than the azides

“…As the reaction temperature was raised to 90°, the yield of 3 increased to 3.7% and that of methanesulfonamide to 0.5%, and some IV-mesylaniline (4, 1.2%) was now formed. At 100°, the yield of 3 dropped to 0.9%, while that of 4 went up to 13.6%. These observations are entirely consistent with the hypothetical situation depicted in Figure 1.…”

“…It is possible that since no 3 is observed at 120°under the reaction conditions the isomerization of 3 -4 is catalyzed by the slightly acidic sulfonamide, as suggested by Breslow.1 Alternatively, it could be that the concentration of 3 at 120°is so small at any time that it would isomerize completely under the reaction conditions unless it were trapped. The azepine could not be detected by gas chromatography, since it was shown that it isomerized quantitatively to the mesylaniline 4 under the glc conditions. We conclude, therefore, that azepine formation is the kinetically controlled process while the aromatic substitution product is that of thermodynamic control in the attack of an aromatic nucleus by a singlet sulfonyl nitrene.…”

Heterocyclic polyfluoro-compounds. Part 41. Photochemical isomerization of 1-substituted hexafluoro-1H-azepines: hexafluoro-2-azabicyclo[3.2.0]hepta-3,6-dienes and their reactions

“…2* Fluorine, and particularly Auoroalkyl group, substitution usually has a beneficial effect upon the stability and ease of formation of strained valence-bond isomer^,^-^ the so-called ' perfluoroalkyl effect ' J 7 which appears to be largely steric in origin. 8 The availability 1 9 9 of the three 1-substituted hexafluoro-1H-azepines (1)-( 3), the last compound being obtained by sulphuric acid hydrolysis of the cyanocompound (a), prompted a study of their isomerization. U.V.…”