A. A. Gall

Diazabicycloalkanes with bridgehead nitrogen atoms. 28. Stevens rearrangement of benzodiazabicycloalkenes

Stevens rearrangement of the benzyl bromides of benzo[b]-1,4-diazabicyclo[2.2.2]octene and benzo[f]-1,5-diazabicyclo[3.2.2]-nonene occurs with expansion of the diazabicyclic fragments to form a mixture of stereoisomers. Both the ethylene and the trimethylene bridges participate in the rearrangement of the nonene.

Diazabicycloalkanes with nitrogen atoms in bridgehead positions. 25. Influence of 3′-substituents on the direction of hydroxyethylation of benzo[b]-1,4-diazabicyclo[2.2.2]octenes

Substituents in the 3′ and 6′-positions of benzo[b]-1,4-diazabicyclo[2.2.2]octane are capable of influencing the reactivity of the nitrogen atoms in the hydroxyethylation reaction due to steric hindrances or anchimeric contribution. Depending on the reaction conditions and substituents in the aromatic ring of benzo[b]-1,4-diazabicyclo[2.2]octane, either mono- or bis-quaternary salts were obtained.

Diazabicycloalkanes with bridgehead nitrogen atoms: 27. Synthesis of phenazino[1?,2?-b]- and phenazino [2?,3?-b]-1,4-diazabicyclo[2.2.2]octenes

Reaction of 4′-iodo- and 4′,5′-diiodobenzo[b]-1,4-diazabicyclo[2.2.2]octenes with o-phenylenediamine under Ullmann condensation conditions gives a mixture of phenazino[1′, 2′-b]- and phenazino[2′, 3′-b]-1,4-diazabicyclo[2.2.2]octenes or only the latter, depending upon the grade of copper.

Diazabicycloalkanes with bridgehead nitrogen atoms

By heating 1-(2-hydroxyethyl)benzo[b]-1-azonium-4-azabicyclo-[2.2.2]octene halides in anhydrous solvents or via thermolysis, opening of the bicycle occurs with formation of the corresponding N-(2-hydroxyethyl)-N′-(2-haloethyl)-1, 2,3,4-tetrahydroquinoxalines. In the presence of base, fission of the hydroxyethyl group principally occurs.

Diazabicycloalkanes with nitrogen atoms in the nodal positions. 21. Heteroatom-promoted lithiation of benzo[b]-1,4-diazabicyclo[2.2.2]octene and introduction of substituents into the annelated benzene ring

The action of n-butyllithium on benzo[b]-1,4-diazabicyclo[2.2.2]octene leads to lithiation in the 3′ position of the aromatic ring. The reaction of this lithium derivative with electrophilic reagents was used to synthesize 3′- and 3′,6′-substituted derivatives of benzo[b]-1,4-diazabicyclo[2.2.2]octene.

Diazabicycloalkanes with bridging nitrogen atoms. 23. Synthesis and properties of benzo[f]-1,5-diazabicyclo[3.2.2]nonen-3-ol

Intramolecular cyclization 1-(2-hydroxyethyl)-2,3,4,5-tetrahydro-1H-1,5-benzodiazepin-3-ol gives benzo[f]-1,5-diazabicyclo[3.2.2]nonen-3-ols. Further treatment with acetic anhydride gives their 3-acetyl derivatives. The stereoisomers have been separated and their substituent configurations shown by PMR spectroscopy.

Diazabicycloalkanes with nitrogen atoms in bridgehead positions. 24. Synthesis and reactions of benzo[f]-1,5-diazabicyclo[3.2.2]nonen-3-one

Benzo[f]-1,5-diazabicyclo[3.2.2]nonen-3-one was synthesized by the oxidation of benzo[f]-1,5-diazabicydo[3.2.2]nonen-3-ol by dimethyl sulfoxide in the presence of N,N′-dicycohexylcarbodiimide and the reactions of this compound with 2,4-dinitrophenylhydrazine, phenylmagnesium bromide, and condensation with 4-nitro-benzaldehyde were carried out. It was shown that on heating with hydrobromic acid, benzo[f]-1,5-diazabicyclo[3.2.2]nonen-3-one undergoes dealkylation with the formation of 1,2,3,4-tetrahydroquinoxaline.

Diazobicycloalkanes with bridgehead nitrogen atoms in nodal positions. 22. Conformational analysis of benzodiazabicycloalkenes. Iterative evaluation of spectral and thermodynamic parameters

Abstract1H and 13C NMR were used to investigate the conformational equilibrium of benzo[f]-1,5-diazabicyclo[3,2.2]nonene and benzo[g]-1,6-diazabicyclo[4.2.2]decene in solution at temperatures from 20 to–110‡C. Benzo[f]-1,5-diazabicyclo[3.2.2]nonene in this temperature interval undergoes rapid conformational exchange, while the conformation ratio changes from 73∶27 to 55∶45. The thermodynamic characteristics of this equilibrium were obtained and some NMR parameters of the individual conformers were estimated. For benzo[g]-1,6-diazabicyclo-[4.2.2]decene it was possible to attain conditions of slow exchange between two conformations whose proportion in the temperature interval studied were almost identical. The kinetics of conformational exchange were investigated and the energy of activation of the process was found to equal 42.3 kJ/mole.

Diazabicycloalkanes with nitrogen atoms in bridgehead positions.: 18. Intramolecular cyclization of 1-(?-haloethyl)-1,2,3,4-tetrahydroquinoxalinium salts in acidic media

Abstract1-Methyl-1-(β-haloethyl)-1,2,3,4-tetrahydroquinoxalinium salts were synthesized and the dependence of the hydrolysis and cyclization rate constants on the acidity of the medium and presence of halide was found. It was determined that the monocations of tetrahydroquinoxalines participate in the formation of the benzo[b]-1,4-diazabicyclo[2.2.2]octene system, since blocking the free electron pair of the tertiary nitrogen atom with a methyl substituent significantly accelerates the cyclization and suppresses the hydrolytic side reaction.

Diazabicycloalkanes with nitrogen atoms in bridgehead positions. 16. Synthesis and properties of benzo[b]-1,4-diazabicyclo[2.2.2]octene and dibenzo[b,e]-1,4-diazabicyclo[2.2.2]octadiene, containing primary aromatic amino acids

Abstract4′-Aminobenzo[1′,2′-b]-1,4-diazabicyclo[2.2.2]octene and 4′-aminodibenzo[1′,2′-b, e]-1,4-diazabicyclo[2.2.2]octadiene have been prepared by cyclization reactions of N-Β-chloroethyl derivatives of 1,2,4-triaminobenzene and aminophenazine, and subsequent catalytic hydrogenation of the corresponding 4′-nitrobenzo[1′,2′-b]-1,4-diazabicyclo[2.2.2]octene and 4-benzylaminodibenzo[1′,2′-b,e]-1,4-diazabicyclo[2.2.2]-octadiene. Using the conversion of these compounds to azides as an example, we have demonstrated the feasibility of applying these primary aromatic amines for the synthesis of derivatives of these heterocycles.