V. A. Samsonov

Reaction of 5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide with electrophilic reagents: Bromine and nitric acid

Reactions of 5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide with bromine and nitric acid lead to the electrophilic substitution of the hydrogen atom in the meta-position with respect to the nitro group. At thebromination the primarily formed 4-bromo-6-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide when kept in the solution loses an oxygen atom forming 4-bromo-6-nitrospiro[benzimidazole-2,1′-cyclohexane] 1-oxide and an isomerization product, 8-bromo-6-nitrospiro[3H-[2,1,4]benzoxadiazine-3,1′-cyclohexane] 4-oxide. The latter exposed to light turns into 4-bromo-6-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide. The reaction of the initial 1,3-dioxide with nitric acid afforded 4,6-dinitrospiro[benzimidazole-2,1′-cyclohexan]-7-ol 1-oxide whose heating in o-dichlorobenzene resulted in 3,5-dinitro-1,8-diazatricyclo[7.5.0.02,7] tetradeca-2(7),3,5,8-tetraen-6-ol.

Photochromism of 3 H -2,1,4-benzoxadiazine 4-oxides with heterocyclic substituents on the benzene ring

Abstract2H-Benzimidazole 1,3-dioxides undergo thermal isomerization to 3H-2,1,4-benzoxadiazine 4-oxides which are converted to 2H-benzimidazole 1-oxides on further heating. Irradiation of 3H-2,1,4-benzoxadiazine 4-oxides with sunlight induces their transformation to 2H-benzimidazole 1,3-dioxides. 3H-2,1,4-Benzoxadiazine 4-oxides containing nucleophilic heterocyclic substituents are considerably more stable to sunlight, and they can be used as photochromic compounds.

Synthesis of 1,5,6,7-tetrahydro-4H-benzimidazol-4-one derivatives from 2,6-bis(hydroxyimino)cyclohexan-1-one

The reaction of 2,6-bis(hydroxyimino)cyclohexan-1-one with aldehydes and ammonia afforded 2-substituted 4-hydroxyimino-4,5,6,7-tetrahydro-1H-benzimidazol-1-ols which were hydrolyzed to 1-hydroxy- 2-R-1,5,6,7-tetrahydro-4H-benzimidazol-4-ones. The N-hydroxy group in the latter can readily by removed by the action of chloroacetone in the presence of a base (potassium carbonate or triethylamine); as a result, 2-substituted 1,5,6,7-tetrahydro-4H-benzimidazol-4-ones were obtained.

Formation of the pyrroline n-oxide ring by interaction of α-isonitrosoketones − derivatives of tetrahydrobenzofurazan and -furoxan with aldehydes and morpholine and some of the reactions of these compounds

Abstractα-Isonitroso ketones, derivatives of tetrahydrobenzofurazan and furoxan, react with aldehydes (acetaldehyde and propionaldehyde) and morpholine to form derivatives of tetrahydropyrrolo[2,3-e]-2,1,3-benzoxadiazole 6-oxide. Treatment of the latter with hydrazine hydrate gave derivatives of 4,5-dihydro-1,2,5-oxadiazolo[3,4-f]cinnoline which are readily dehydrogenated with tetrachloro-benzoquinone to derivatives of 1,2,5-oxadiazolo[3,4-f]cinnoline. Reduction of tetrahydropyrrolo[2,3-e]-2,1,3-benzoxadiazole 6-oxides with sodium borohydride gave derivatives of N-hydroxyhexahydro-pyrrolo[2,3-e]-2,1,3-benzoxazole.

Formation of the pyrroline-N-oxide ring by the reaction of isonitrosoketones with enamines and some conversions of the pyrroline-N-oxides obtained

Compounds containing the pyrroline-N-oxide ring are obtained when isonitrosoketones — 2,6-dihydroxyiminocyclohexanone and ω-isonitrosoacetophenone — react with enamines. The compounds obtained behave as synthetic equivalents of 1,4-dicarbonyl compounds when undergoing reaction with amines, hydrazine, and hydroxylatnine.

Formation of o-nitrosoalkylaminobenzenes in the reaction of benzofurazan s with alcohols in acidic conditions

SummaryIn the reaction of benzofurazan with isopropanol cyclohexanol o-nitrosoaalkylaminobenzenes are formed besides 2,2-dialkyl-2H-benzimidazole-oxides. In the instance of 4-aminobenzofurazan only 2-nitroso-3-aklaminoanilines are obtained. 5-Nitrobenzofurazan reacts with isopropranol in sulfuric acid to form 4-nitro-2-nitrosoisopropylaminobenzene; however, in the instance of 4-nitrobenzofurazan derivatives the formation of o-nitrosoalkylaminobenzenes has not been observed.

Synthesis of new 2H-benzimidazole 1,3-dioxide derivatives analogous to separase inhibitor (Sepin-1)

New biologically active 2H-benzimidazole 1,3-dioxide derivatives, analogs of Sepin-1, have been synthesized starting from benzofuroxan. Electrophilic substitution of hydrogen in the 2H-benzimidazole ring occurs at different positions, depending on the electrophile nature.

Formation of 1-aminophenazine from 3,4-dihydrophenazin-1(2 H )-one oxime in the system acetylene–KOH–DMSO

The reaction of 3,4-dihydrophenazin-1(2H)-one oxime with acetylene in the superbasic system KOH–DMSO afforded 1-aminophenazine in 32% yield instead of the expected pyrrolophenazine. The same product was also obtained under analogous conditions in the absence of acetylene.

Unusual Reaction of 6,8-Dichloro-3,3-dimethyl-7-nitro-3H-2,1,4-benzoxadiazine 4-Oxide with 4-Aminomorpholine

Reaction of 6,8-dichloro-3,3-dimethyl-7-nitro-3H-2,1,4-benzoxadiazine 4-oxide with 4-aminomorpholine occurred through the benzoxadiazine ring opening to form 1,2-bis(2-amino-3,5-dichloro-4-nitrophenyl)-diazene oxide instead of the substitution product.

Formation of 5,6,7,8-tetrahydroquinoxaline 1,4-dioxide derivatives in the reaction of cyclohexane-1,2-dione dioxime with 1,2-diketones

A reaction of cyclohexane-1,2-dione dioxime with diacetyl leads to tetrahydroquinoxaline 1,4-dioxide derivatives: 5-(E)-{[(E)-2-(hydroxyimino)cyclohexylidene]aminooxy}-2,3-dimethyl-5,6,7,8-tetrahydroquinoxaline 1,4-dioxide and 5,5´-(1E,1´E)-cyclohexane-1,2-diylidenebis(azan-1-yl-1-ylidene)bis(oxy)bis(2,3-dimethyl-5,6,7,8-tetrahydroquinoxaline 1,4-dioxide). Similar products were obtained in the reaction of cyclohexane-1,2-dione dioxime with cyclohexane-1,2-dione and hexane-3,4-dione.