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2-Amino-(1-(2-nitrophenylsulfinyl)azulene derivatives were synthesized by the reaction of 2-aminoazulene with 2-nitrobenzenesulfonyl chloride. Crystal structures of these compounds were determined by X-ray diffraction analysis. The sulfur atom derived nosyl group shows unique geometry. Furthermore, a reaction using 4-nitrobenzenesulfonyl chloride is also demonstrated.

Article, TETRAHEDRON LETTERS. 48(26): 4471-4475 (2007)

6-Chloro-7H-naphth[3,2,1-cd]azulen-7-ones 9a and 10a easily react with some nucleophiles (sodium methoxide, potassium hydrosulfide, and amines) to give the corresponding 6-substituted products. Halogenation of 7H-naphth[3,2,1-cd]azulen-7-ones with N-halosuccinimides occurs at the C-5 position. Grignard reagents add to 7H-naphth[3,2,1-cd]azulen-7-ones at the seven-membered ring and a subsequent dehydrogenation gives 2-, 3- and 4-substituted products; reactive tendency of the positions of 7H-naphth[3,2,1-cd]azulen-7-one toward the reagents was 6 ≫ 3 > 4 > 2, whereas the steric hindrance was (6 >) 4 > 3 > 2. Condensation of 7H-naphth[3,2,1-cd]azulen-7-ones with active methylene compounds in boiling acetic anhydride occurs at the carbonyl group and gives the corresponding 7-methylene-7H-naphth[3,2,1-cd]azulene derivatives. 6-Hydroxy-7H-naphth[3,2,1-cd]azulen-7-one 7 is obtained by the hydrolysis of 6-methoxy-7H-naphth[3,2,1-cd]azulen-7-one 9b with hydrobromic acid, in almost quantitative yield. Compound 7 exists in a tautomeric mixture with 7-hydroxy-6H-naphth[3,2,1-cd]azulen-6-one 8. Methylation of 7 with diazomethane gives 9b and 7-methoxy-6H-naphth[3,2,1-cd]azulen-6-one 18a in 75% and 25% yield, respectively. Chlorination of 7 with thionyl dichloride also gives a pair of isomers, 5,6-dichloro-7H-naphth[3,2,1-cd]azulen-7-one 11b and 5,7-dichloro-6H-naphth[3,2,1-cd]azulen-6-one 18b. A tautomerism between 6-(substituted methyl)-7H-naphth[3,2,1-cd]azulen-7-ones and 7-hydroxy-6H-naphth[3,2,1-cd]azulen-6-ylidenemethylene derivative is also studied.

Reactions of diethyl azulene-1,3-dicarboxylate (1) and diethyl 2-chloroazulene-1,3-dicarboxylate (11) with Grignard reagents, followed by dehydration with tetrachloro-1,2-benzoquinone, gave 2-, 4,- and 6-substituted addition–oxidation products. Grignards reagents have a tendency to react with 1 at the positions in the order of 2 > 4 > 6, while steric hindrance has a greater influence at the positions in order of 2 > 4 > 6. Reactions of 1 and 11 with phenyllithium and methyllithium gave similar results. On the other hand, on the reaction of diethyl 2-methoxyazulene-1,3-dicarboxylate (15), Grignard reagents attacked preferentially at the methoxy group, and 2-substituted products were obtained. Use of excess molar equivalents of Grignard reagents led to diaryl-substituted products. Reaction of 2-chloro-1-azaazulenes with Grignard reagents also gave similar addition–oxidation products, and reacted at the positions in the order 8 ≫ 4 > 6, whereas reaction of 2-methoxy-1-azaazulene with a Grignard reagent gave 1-azaazulen-2(1H)-one.

The iodination of azulene derivatives of type (I) or (VI) and some consecutive reactions are studied.

Syntheses and cycloadditions of ethyl 2-(benzylidene)hydrazino-1-azaazulene-3-carboxylates were investigated. Condensations of ethyl 2-hydrazino-1-azaazulene-3-carboxylate with benzaldehyde and p-methoxybenzaldehyde gave corresponding hydrazones in good yields. Reactions of ethyl 2-(benzylidene)hydrazino-1-azaazulene-3-carboxylate (2a) and ethyl 2-(p-methoxybenzylidene)hydrazino-1-azaazulene-3-carboxylate with dimethyl acetylenedicarboxylate gave novel 1 : 2-adducts, 4a,11,11a-triazaindeno[5,6-a]azulene derivatives and 2-methoxycarbonylimino-1-(2-pyrrolylmethyl)-1-azaazulene derivatives as major products. Reaction of 2a with electron deficient olefins (tetracyanoethylene, N-methylmaleimide) gave no cycloadduct but a cyclization product of 2a, 3-phenyl-1,2,3a-triazacyclopent[a]azulene-9-carboxylate. The structures of the obtained compounds were analyzed by inspections of their physical and spectral data, and by single-crystal X-ray analyses of some of these compounds. The reaction mechanisms of these react...

Cycloadditions of the title compounds with dimethyl acetylenedicarboxylate gave 1:2-cycloadducts. The structural assignments of the products were deduced by spectral inspections; the structure for one compound was established by X-ray crystallography.

The reactions of 2- and 8-(substituted amino)-1-azaazulenes with dimethyl acetylenedicarboxylate (DMAD) were investigated. Treatment of ethyl 2-acetylamino-1-azaazulene-3-carboxylate with DMAD in refluxing acetonitrile gave 9-ethyl 1,2,3-trimethyl 3a-azacyclopent[a]azulene-1,2,3,9-tetracarboxylate, 5-ethyl 1,2,2a,3-tetramethyl 4-acetyl-2a,3-dihydro-4H-4, 10b-diazapentaleno[1,6-aj]azulene-1,2,2a,3,5-pentacarboxylate (3a), and dimethyl (10-ethoxycarbonyl-4-methoxycarbonyl-2,4a-dihydro-2-oxo-2H-1,4a-diazabenz[a]azulen-3-yl)maleate. Compound 3a thermally rearranged to 9-ethyl 2,3,10,11-tetramethyl 1-acetyl-2,3,4,4a-tetrahydro-1H-1,4-diaza-3,4a-ethenofluorene-2,3,9,10,11-pentacarboxylate. The reaction of ethyl 2-alkylamino-1-azaazulene-3-carboxylate with DMAD gave the corresponding 4-alkyl-2a,3-dihydro-4H-4,10b-diazapentaleno[1,6-aj]azulene derivatives, and the etheno-bridged 1-azaheptalene derivative. The reaction of 8-ethylamino-3-phenyl-1-azaazulene with DMAD gave trimethyl 1-phenyl-2a-azabenz[cd]azulene-3,...

Syntheses and cycloadditions of ethyl 2-(benzylidene)hydrazino-1-azaazulene-3-carboxylates were investigated. Condensations of ethyl 2-hydrazino-1-azaazulene-3-carboxylate with benzaldehyde and p-methoxybenzaldehyde gave corresponding hydrazones in good yields. Reactions of ethyl 2-(benzylidene)hydrazino-1-azaazulene-3-carboxylate (2a) and ethyl 2-(p-methoxybenzylidene)hydrazino-1-azaazulene-3-carboxylate with dimethyl acetylenedicarboxylate gave novel 1 : 2-adducts, 4a,11,11a-triazaindeno[5,6-a]azulene derivatives and 2-methoxycarbonylimino-1-(2-pyrrolylmethyl)-1-azaazulene derivatives as major products. Reaction of 2a with electron deficient olefins (tetracyanoethylene, N-methylmaleimide) gave no cycloadduct but a cyclization product of 2a, 3-phenyl-1,2,3a-triazacyclopent[a]azulene-9-carboxylate. The structures of the obtained compounds were analyzed by inspections of their physical and spectral data, and by single-crystal X-ray analyses of some of these compounds. The reaction mechanisms of these react...

The reactions of sodium salt of 2-methoxy-1-azaazulene-3-carboxyaldehyde tosylhydrazone with styrenes gave 3,8-cyclohexeno-2-methoxy-1-azaazulenes and 3-cyclopropyl-2-methoxy-1-azaazulenes. The formers were afforded through the diazo compound generated from the tosylhydrazone and the latters were yielded via the carbene derived from the diazo compound. The reactions with stilbenes gave the corresponding cyclopropane derivatives. The similar reactions with sodium salt of azulene-1-carboxaldehyde tosylhydrazone gave the analogous result

Amination of azaazulenes 1–3 with O-mesitylsulfonylhydroxylamine occurs at N-1 and gives the corresponding azaazulenium salts 4–6. The treatment of the salts 4 and 6 with potassium carbonate gives 1-amino-2-imino-1,2-dihydro-1,3-diaza- and 1-azaazulenes. The structure of 1-amino-2-ethylimino-1,2-dihydro-1-azaazulene (10) was characterized by X-ray crystal structure analysis. Reaction of the salt 4 with acetic anhydride gave 2-methyl-1,3,3a,9-tetraazacyclopent[a]azulene. The reaction of the salts 4 and 5 with diethyl ethoxymethylenedicarboxylate (DEEM) in the presence of potassium carbonate in acetonitrile gave 1,3,3a,9-tetraaza- (19) and 1,3,3a-triazacyclopent[a]azulene derivatives (21) as major products, whereas the reaction in ethanol gave 1,2a,3-triaza- (17) and 2a,3-diazabenz[cd]azulene derivatives (22), respectively. Similar treatment of 6 with DEEM gave diethyl (2-ethylimino-1,2-dihydro-1-azaazulen-1-yl)aminomethylenemalonate 23, which converted to 2a,3-diazabenz[cd]azulene derivative (24). The salts 4–6 reacted with active methylene compounds such as diethyl acetonedicarboxylate, diethyl oxalacetate and ethyl pyruvate, at the N-amino group followed by a cyclization at the C-8 position on the azaazulene ring to give 1,2a,3-triaza- (25, 28, 29) and 2a,3-diazabenz[cd]azulene derivatives (26, 27, 30). Cycloaddition of the salts 4–6 with acetylenic esters in the presence of potassium carbonate proceeded regioselectively and gave 1,2a,3-triaza- (32–35) or 2a,3-diazabenz[cd]azulene derivatives (31, 36, 37, 39–41).

6-Chloro-7H-naphth[3,2,1-cd]azulen-7-ones 9a and 10a easily react with some nucleophiles (sodium methoxide, potassium hydrosulfide, and amines) to give the corresponding 6-substituted products. Halogenation of 7H-naphth[3,2,1-cd]azulen-7-ones with N-halosuccinimides occurs at the C-5 position. Grignard reagents add to 7H-naphth[3,2,1-cd]azulen-7-ones at the seven-membered ring and a subsequent dehydrogenation gives 2-, 3- and 4-substituted products; reactive tendency of the positions of 7H-naphth[3,2,1-cd]azulen-7-one toward the reagents was 6 ≫ 3 > 4 > 2, whereas the steric hindrance was (6 >) 4 > 3 > 2. Condensation of 7H-naphth[3,2,1-cd]azulen-7-ones with active methylene compounds in boiling acetic anhydride occurs at the carbonyl group and gives the corresponding 7-methylene-7H-naphth[3,2,1-cd]azulene derivatives. 6-Hydroxy-7H-naphth[3,2,1-cd]azulen-7-one 7 is obtained by the hydrolysis of 6-methoxy-7H-naphth[3,2,1-cd]azulen-7-one 9b with hydrobromic acid, in almost quantitative yield. Compound 7 exists in a tautomeric mixture with 7-hydroxy-6H-naphth[3,2,1-cd]azulen-6-one 8. Methylation of 7 with diazomethane gives 9b and 7-methoxy-6H-naphth[3,2,1-cd]azulen-6-one 18a in 75% and 25% yield, respectively. Chlorination of 7 with thionyl dichloride also gives a pair of isomers, 5,6-dichloro-7H-naphth[3,2,1-cd]azulen-7-one 11b and 5,7-dichloro-6H-naphth[3,2,1-cd]azulen-6-one 18b. A tautomerism between 6-(substituted methyl)-7H-naphth[3,2,1-cd]azulen-7-ones and 7-hydroxy-6H-naphth[3,2,1-cd]azulen-6-ylidenemethylene derivative is also studied.

The reactions of 2- and 8-(substituted amino)-1-azaazulenes with dimethyl acetylenedicarboxylate (DMAD) were investigated. Treatment of ethyl 2-acetylamino-1-azaazulene-3-carboxylate with DMAD in refluxing acetonitrile gave 9-ethyl 1,2,3-trimethyl 3a-azacyclopent[a]azulene-1,2,3,9-tetracarboxylate, 5-ethyl 1,2,2a,3-tetramethyl 4-acetyl-2a,3-dihydro-4H-4, 10b-diazapentaleno[1,6-aj]azulene-1,2,2a,3,5-pentacarboxylate (3a), and dimethyl (10-ethoxycarbonyl-4-methoxycarbonyl-2,4a-dihydro-2-oxo-2H-1,4a-diazabenz[a]azulen-3-yl)maleate. Compound 3a thermally rearranged to 9-ethyl 2,3,10,11-tetramethyl 1-acetyl-2,3,4,4a-tetrahydro-1H-1,4-diaza-3,4a-ethenofluorene-2,3,9,10,11-pentacarboxylate. The reaction of ethyl 2-alkylamino-1-azaazulene-3-carboxylate with DMAD gave the corresponding 4-alkyl-2a,3-dihydro-4H-4,10b-diazapentaleno[1,6-aj]azulene derivatives, and the etheno-bridged 1-azaheptalene derivative. The reaction of 8-ethylamino-3-phenyl-1-azaazulene with DMAD gave trimethyl 1-phenyl-2a-azabenz[cd]azulene-3,...

Trimethylsilylethynyl)- and 3-(phenylethynyl)-2-(triphenyl- phosphoimino)-1-azaazulenes were synthesized by the Appel reaction of the corresponding 2-amino-3-ethynyl-1-azaazulenes. Reaction of 3-(phenyl- ethynyl)-2-(triphenylphosphoimino)-1-azaazulene (8b) with Cu(OTf)2 gave 3-(2-oxophenethyl)-2-(triphenylphosphoimino)-1-azaazulene (11), 3-(1,2-dioxo- phenethyl)-2-(triphenylphosphoimino)-1-azaazulene (12), and 2-amino-3-(1,2- dioxophenethyl)-1-azaazulene (13). The structure of 13 was decided by X-ray structure analysis, and the structure of 12 was discussed by molecular orbital calculation. Reaction of 8b with aryl isocyanate in the presence of benzoyl peroxide gave 1,10-diazabenz(a)azulene derivative.

3-Iodo-1-azaazulenes were easily ethynylated by Sonogashira-Hagihara reaction to give 3-ethynyl-1-azaazulenes. Cyclization of 2-amino-3- ethynyl-1-azaazulene was achieved by heating in the presence of copper(II) acetate or copper(II) trifluoromethanesulfonate, and 1,9-diaza-1H-cyclopent[a]azulene derivatives were obtained. Reaction of 2-chloro-1-azaazulene with lithium phenylacetylide gave 3-chloro-1-(2-chloro-1-azaazulen-8-yl)-2-phenyl-2a-aza-2H-cyclopent[cd]azulene together with 2-chloro-8-phenylethynyl-1-azaazulene.

Reactions of diethyl azulene-1,3-dicarboxylate (1) and diethyl 2-chloroazulene-1,3-dicarboxylate (11) with Grignard reagents, followed by dehydration with tetrachloro-1,2-benzoquinone, gave 2-, 4,- and 6-substituted addition–oxidation products. Grignards reagents have a tendency to react with 1 at the positions in the order of 2 > 4 > 6, while steric hindrance has a greater influence at the positions in order of 2 > 4 > 6. Reactions of 1 and 11 with phenyllithium and methyllithium gave similar results. On the other hand, on the reaction of diethyl 2-methoxyazulene-1,3-dicarboxylate (15), Grignard reagents attacked preferentially at the methoxy group, and 2-substituted products were obtained. Use of excess molar equivalents of Grignard reagents led to diaryl-substituted products. Reaction of 2-chloro-1-azaazulenes with Grignard reagents also gave similar addition–oxidation products, and reacted at the positions in the order 8 ≫ 4 > 6, whereas reaction of 2-methoxy-1-azaazulene with a Grignard reagent gave 1-azaazulen-2(1H)-one.

Cycloadditions of the title compounds with dimethyl acetylenedicarboxylate gave 1:2-cycloadducts. The structural assignments of the products were deduced by spectral inspections; the structure for one compound was established by X-ray crystallography.

Reactiond of 2-(N, N-dimethylamino)- and 2-(N, N-diethylamino)tropones with palladium (II) acetate in benzene in the presence of sodium acetate afforded the corresponding 7-acetoxylated 2-aminotropones. A similar acetoxylation reaction proceeded with azulene to give 1-acetoxy- and 1, 3-diacetoxyazulenes. On the other hand, phenylation at the 7-position occurred in the reaciton using 2-(N-methyl)anilinotoropone. The acetoxylations are considered to proceed through radical cation complexes formed through oxidation of amino groups by palladium.

3,4-Dibenzoyl-1-phenyl-2a,5-diazabenz[cd]azulene (2b) was synthesized by cycloaddition of 8-amino3-phenyl-1-azaazulene with dibenzoylacetylene. Heteroannulation to 2b has been achieved by reactions with hydrazine and phosphorus pentasulfide.

3,4-Dibenzoyl-1-phenyl-2a,5-diazabenz[cd]azulene (2b) was synthesized by cycloaddition of 8-amino3-phenyl-1-azaazulene with dibenzoylacetylene. Heteroannulation to 2b has been achieved by reactions with hydrazine and phosphorus pentasulfide.

Trimethylsilylethynyl)- and 3-(phenylethynyl)-2-(triphenyl- phosphoimino)-1-azaazulenes were synthesized by the Appel reaction of the corresponding 2-amino-3-ethynyl-1-azaazulenes. Reaction of 3-(phenyl- ethynyl)-2-(triphenylphosphoimino)-1-azaazulene (8b) with Cu(OTf)2 gave 3-(2-oxophenethyl)-2-(triphenylphosphoimino)-1-azaazulene (11), 3-(1,2-dioxo- phenethyl)-2-(triphenylphosphoimino)-1-azaazulene (12), and 2-amino-3-(1,2- dioxophenethyl)-1-azaazulene (13). The structure of 13 was decided by X-ray structure analysis, and the structure of 12 was discussed by molecular orbital calculation. Reaction of 8b with aryl isocyanate in the presence of benzoyl peroxide gave 1,10-diazabenz(a)azulene derivative.

3-Ethynyl-1-azaazulene derivatives were obtained by Sonogashira-Hagihara reaction of 3-iodo-2-chloro-1-azaazulenes, and 2-(phenylethynyl)-1-azaazulenes were obtained by the reaction of 2-bromo-l-azaazulenes. Glaser reaction of 2-chloro-3-ethynyl-1-azaazulenes gave 1,4-bis(2-chloro-1-azaazulen-3-yl)-13-butadiyne. Treatment of 2-chloro-3-ethynyl-1-azaazulene derivatives with sodium hydrosulfide gave corresponding 1-thia-9-azacyclopent[a]azulene derivatives in good yield.

2-Chloro-, 2-methoxy-, and 2-amino-l-azaazulenium 1-methylides and 1,3-diazaazulenium 1-methylide were generated by the treatment of the corresponding 1-trimethylsilylmethyl-1-azaazulenium triflates and 1-trimethylsilylmethyl-1,3-diazaazulenium triflate with CsF; the triflates were prepared from the corresponding 1-azaazulenes and 1,3-diazaazulene with trimethylsilylmethyl triflate. The 1,3-dipolar cycloadditions of the 2-chloro-1-azazaazulenium 1-methylide, prepared in situ, with acetylenic esters gave 2a-azabenz[cd]azulene derivatives and 3a-azacyclopenta[a]naphthalene derivatives as major products, whereas 2-piperizino-1-azaazulenium 1-methylide underwent extended dipolar cycloaddition with acetylenic esters and afforded 9b-azacyclopent|a]azulene derivatives as major products.

Reaction of 3-phenyl-8-triphenylphosphoimino-1-azaazulene (1) with some aryl isocyanates gave 2-arylimino-4-phenyl-2,2a-dihydro-1,2a-diazacyclopent[cd]azulenes (2) and 8-arylimino-1,8-dihydro-1-azaazulenes (3). Reaction of 1 with p-toluenesulfonyl isocyanate gave 2-imino-3-(p-methylphenyl)-4-phenyl-2,2a-dihydro-1,2a-diazacyclopent[cd]azulene as cyclization-rearrangement product. Reaction of phenyl isothiocyanate gave 2. Tautomerization of between 8-imino-1,8-dihydro-1-azaazulenes (3) and 8-amino-1-azaazulenes was discussed on the basis of X-Ray structure analysis and molecular orbital calculation.

Reaction of 3-phenyl-8-triphenylphosphoimino-1-azaazulene (1) with arylaldehyde gave 2-aryl-4-phenyl-3H-1,2a-diazacyclopent[cd]azulenes. Reaction of 1 with trans-cinnamaldehyde gave 3-benzyl-1-pheny-2a,5-diazabenz[cd]azulene as cyclization product. Cycloaddition reaction of 1 with dimethyl acetylenedicarboxylate gave tetramethyl 4-phenyl-9,9b-diazaindeno[4,3a,3,2-bcd]azulene-1,2,3,9a-tetracarboxylate and hexamethyl 6-phenyl-3aH-10c-azaacephenanthryene-1,2,3,3a,4,5-hexacarboxylate.

2-Substituted 1-azaazulene N-ylides were generated by the treatment of appropriate 1-trimethylsilylmethyl-1-azaazulenium triflates with CsF; the triflate salts were prepared from 1-azaazulenes and trimethylsilylmethyl triflate. The 1,3-Bipolar cycloadditions of 2-chloro-1-azaazulene N-ylide, prepared in situ, with acetylenic esters gave 2a-azabenz[cd]azulene derivatives and 3a-azacyclopent[a]naphthalene derivatives. These structures were determined by X-Ray crystal structure analysis. A similar reaction of 2-piperidino-1-azaazulene N-ylide gave 3a-azacyclopent[a]azulene derivative as major product.

Chloroketene reacted with 8-amino-3-phenyl-1-azaazulene (1) to give 2,2a-dihydro-2a-azacyclopent[cd]azulen-2-one derivative (2a), as a cycloadduct, along with ethyl (3-phenyl-1-azaazulen-8-yl)aminocarboxylate (3a) and 8-chloroacetylamino-3-phenyl-1-azamulene (4a). Compound (2a) was formed by the reaction of 4a with chloroketene. Formation mechanism of 2a, 3a and 4 was discussed. Phenylketene and diphenylketene reacted with 1 to give 8-phenylacetylamino- (4b) and 8-diphenylacetylamino-3-phenyl-1-waazulene (6) as major products,respectively. Further treatment of 6 with diphenylketene gave 2-diphenylmethylene-4-phenyl-2,2a-dihydro-1,2a-diazacyclopent[cd]azulene (7).

3-Phenyl-7,8-dehydro-1-azaazulenes were generated by the treatment of 8-bromo-3-phenyl-1-azaazulenes with potassium t-butoxide in DMSO or in THF in the presence of 16-crown-8-ether, and trapped with diphenylisobenzofuran as 3,7,12-triphenyl-1-aza-7,12-epoxynaphth[2,3-e]azulenes. The structure of the adduct, 2-bromo-3,7, 12-triphenyl-1-aza-7,12-epoxynaphth[2,3-e]azulene, was deduced by X-Ray structure analysis. Similar treatment of 8-bromo-3-phenyl-1-azaazulene with potassium t-butoxide in the presence of furan gave 3-phenyl-1-aza-7,12-epoxynaphth[2,3-e]azulene and 7-phenyl-3H-3a,3c-dihydro-1-aza-3-oxacyclopenta[3,4]cyclobuta[1,2-e]azulene as cycloadducts.

Azulene reacted with heterocumulenes in the presence of Lewis acid to give 1-substituted azulenes whereas 2-aminoazulenes reacted with heterocumulenes to give 2-(substituted amino)azulenes together with 1-substituted azulenes.

8-[(E)-Styryl]-1-azaazulenes stereospecifically react with dimethyl acetylenedicarboxylate to form trans-7H-6a-azacyclobuta[j]cyclopent[cd]azulene (3), which undergoes thermal rearrangement into 3-[(E)-styryl]3H-2a-azacyclopent[cd]azulene and 3a,4-dihydro-3H-2a-azadicyclopent[cd, ij]azulene (7), or isomerization into 3H-2a-azacyclopenta[ef]heptalene by silica gel. Compound 7 is oxidized during the course of reaction to yield 11-oxo-2aH-7,10b-methano-2a-azacyclopenta[ab]cycloundecene, compound 3 forming 5a,6-dihydro-3H-2a-azadicyclopenta[ef, kl]heptalene upon reaction with acetylene. The formation of 3 could be accounted for in terms of a symmetry-allowed thermal [π2s+π2a+π6a] cycloaddition.

The reaction of 1-methyl-1-azaazulen-2(1H)-one (1a) with dimethyl acetylenedicarboxylate (DMAD) or dibenzoylacetylene (DBA) in refluxing acetonitrile gave 1,2-disubstituted azulene (2), 2-methylcyclopent[de]isoquinolin-3(2H)-ones, 1-methyl-1-azacyclopent[cd]azulen-2(1H)-ones, and 3-substituted 1-methyl-1-azaazulen-2(1H)-ones, whereas in refluxing t-butylbenzene, compound 2 and 6,8-etheno-1-methylcyclohepta[b]pyrrol-2(1H)-one were obtained as major products. The reactions proceeded periselectively depending on the temperature. 2-Hydroxy-1-azaazulene behaved as 1-azaazulen-2(1H)-one and the reaction with DMAD gave similar result as for 1a. The reaction of 2-amino-1-azaazulene with DMAD gave methyl 2,4a-dihydro-2-oxo-1,4a-diazabenz[a]azulene-4-carboxylate and tetramethyl 4,5-dihydro-1H-1,11-diazacyclohept[a]azulene-2,3,4,5-tetracarboxylate. The reaction of 2-mercapto-1-azaazulene with DMAD gave tetramethyl 4,4a-dihydro-4a-azabenz[a]azulene-1,2,3,4-tetracarboxylate in moderate yield. The reaction mechanisms o...

Das E-Styryl-azaazulen (I) reagiert mit Acetylendicarbonsauredimethylester in siedendem Benzol unter Bildung eines Gemisches der Addukte (III)-(VI), in siedendem Xylol unter Bildung eines Gemisches von (V)-(VIII); primar entsteht in beiden Fallen (III), das sich thermisch unter Bildung von (V) und (VII) umlagern, mit weiterem (II) unter Bildung von (VI) reagieren oder unter Bildung von (IV) isomerisieren kann.

Cycloheptimidazole reacted with electrondeficient olefins (e.g., ethyl acrylate or acrylonitrile) to give the regioselective [6+2] cycloadducts, which were readily dehydrogenated to give 2a,3-dihydro-1,2a-diazacyclopent[cd]azulenes.

The reaction of 1-methyl-1-azaazulen-2(1H)-one (1a) with dimethyl acetylenedicarboxylate (DMAD) or dibenzoylacetylene (DBA) in refluxing acetonitrile gave 1,2-disubstituted azulene (2), 2-methylcyclopent[de]isoquinolin-3(2H)-ones, 1-methyl-1-azacyclopent[cd]azulen-2(1H)-ones, and 3-substituted 1-methyl-1-azaazulen-2(1H)-ones, whereas in refluxing t-butylbenzene, compound 2 and 6,8-etheno-1-methylcyclohepta[b]pyrrol-2(1H)-one were obtained as major products. The reactions proceeded periselectively depending on the temperature. 2-Hydroxy-1-azaazulene behaved as 1-azaazulen-2(1H)-one and the reaction with DMAD gave similar result as for 1a. The reaction of 2-amino-1-azaazulene with DMAD gave methyl 2,4a-dihydro-2-oxo-1,4a-diazabenz[a]azulene-4-carboxylate and tetramethyl 4,5-dihydro-1H-1,11-diazacyclohept[a]azulene-2,3,4,5-tetracarboxylate. The reaction of 2-mercapto-1-azaazulene with DMAD gave tetramethyl 4,4a-dihydro-4a-azabenz[a]azulene-1,2,3,4-tetracarboxylate in moderate yield. The reaction mechanisms o...

Mit uberschussigem (II) bilden die Styrylcycloheptapyrrole (I) in siedendem Benzol die Cycloaddukte (III) und (IV), von denen letztere auch durch Erwarmen von (III) in siedendem Xylol erhalten werden.

Cycloheptimidazole reacted with electrondeficient olefins (e.g., ethyl acrylate or acrylonitrile) to give the regioselective [6+2] cycloadducts, which were readily dehydrogenated to give 2a,3-dihydro-1,2a-diazacyclopent[cd]azulenes.

2-Alkoxycyclohepta[b] pyrroles reacted with dimethyl acetylenedicarboxylate to give tetramethyl 2-alkoxy-3H-2a-azacyclopenta[ef]heptalene-3,4,5,6-tetracarboxylates in benzene and dialkyl 2-(2-alkoxycyclohepta[b]pyrrol-1-yl)fumarate in alcoholic solvents.

The cycloaddition of 8-styrylcyclohepta[b]pyrroles with dimethyl acetylenedicarboxylate give the 7H-6a-azacyclobuta[j]cyclopenta[1,2,3-cd]azulene ring system, which rearranges thermally into the 3H-2a-azacyclopenta[cd]azulene ring system.

Cyclohepta[b]pyrroles (1) and cycloheptimidazole (2) react with dimethyl acetylenedicarboxylate to give 2H-2a-azacyclopent[cd]azulenes (3) and 3H-2a-azacyclopenta[ef]heptalenes (4), and 3H-1,2a-diazacyclopenta[ef]-heptalene (5), respectively, in low to moderate yields. The formation of these products is explained in terms of 1,8-dipolar cycloaddition reactions.