Photochemie von 1,1-Dimethyl-4-phenyl- und 1-Methyl-1-phenyl-1,2-dihydronaphthalin; Nachweis einer photochemischen,sigmatropischen [1,7]H-Verschiebung. 41. Mitteilung über Photoreaktionen

Photochemistry of 1,1-dimethyl-4-phenyl-and 1-Methyl-1-phenyl-1,2-dihydronaphthalene; evidence for a photochemical, sigmatropic [1,7]H-shift. Irradiation of 1,1-dimethyl-4-phenyl-1,2-dihydronaphthalene ( 11 ) and 1-methyl-1-phenyl-1,2-dihydronaphthalene ( 8 ) in pentane were investigated at ?112° to ?118°, using a mercury high pressure lamp. The [1,5]-hydrogen-shift products 13 and 17 , respectively, the [1,7]-hydrogen-shift products 15 and 10 , respectively and the photochemical Diels-Alder products 14 and 18 , respectively, were obtained, presumably via the ω-vinyl-o-quinodimethane intermediates 12 and 9 (Schema 3). Irradiation of the 1,2-dihydronaphthalene 11 at ?181° to ?183° in a 2,2-dimethylbutane/pentane matrix, gave rise to an UV.-maximum at 402 nm which is assigned to the o-quinodimethane derivative 12 . After warming the solution around ?130° or to room temperature, a product mixture was obtained, which mainly consist of the [1,7]-hydrogen-shift product 15 accompanied by the [1,5]-hydrogen-shift products 13 and 16 and the photochemical Diels-Alder product 14 (Table 1). When the o-quinodimethane intermediate 12 was irradiated with 406 nm-light, the longwavelength absorption completely disappeared. This solution, after warmingup, yielded mainly the [1,5]-hydrogen-shift products 13 and 16 together with the bicyclic compound 14 and surprisingly a small amount of the [1,7]-hydrogen-shift product 15 (Table 1). Similar experiments were carried out with the 1,2-dihydronaphthalene 8 . The results clearly indicate that irradiation of the o-quinodimethane 9 at ?180° to ?185° with 406 nm-light caused [1,5]- and [1,7]-hydrogen shifts in a ratio of approximately 1:1 (Table 2). From the experiments described above it follows, that the phenyl-substituted α-methyl-ω-vinyl-o-quinodimethanes 12 and 9 undergo upon irradiation with light of λ > 400 nm, besides photochemical Diels-Alder reactions, also [1,5]- and [1,7]- hydrogen shifts. It is remarkable that the thermal [1,7]-hydrogen-shifts of the o-quinodimethanes 12 and 9 occur readily around ?130°, whilst a temperature of ?70° is needed to promote [1,7]-hydrogen-shifts in the non-phenylated o-quinodimethanes of the type 2 (Schema 1). The phenyl group in ω- or α-position may enter into conjugation with the π-system in the helcal transition state of the [1,7]-hydrogen shift, but not in the reactants 12 and 9 .     

Photocycloaddition of 2-Cyanocycloalk-2-Enones to 2, 3-Dimethylbut-2-Ene

Irradiation of 5,5-dimethyl-6-oxocyclohex- l-ene- l-carbonitrile ( 1 ) in the presence of 2,3-dimethylbut-2-ene afforded 3,3,4,4,7,7-hexamethyl-3,4,4a,5,6,7-hexahydroindeno[1,7-c,d]-],2-oxazole (3) in nearly quantitative yield. In contrast, 4,4-dimethyl-5-oxo-cyclopent-l-ene-l-carbonitrile ( 2 ) under the same conditions reacted not to a tricyclic isoxazole but to a 2:1 mixture of 3,3,6,6,7,7-hexamethyl-2-oxo-bicyclo[3.2.0]heptane-l-carbonitrile ( 4 ) and trans-3,3-dimethyl-2-oxo-5-(2,3-dimethylbut-3-en-2-yl)cyclopentane-l-carbonitrile ( 5 ), respectively.     

Reactions of dialkyl 4-bromo-2,2-dimethyl-3-oxohexane-1,6-dioates,-heptane-1,7-dioates with zinc and aromatic aldehydes

Zinc enolates generated from dimethyl 4-bromo-2,2-dimethyl-3-oxohexane-1,6-dioate and zinc reacted with aromatic aldehydes giving methyl 2,2-dimethyl-3-oxo-3-(5-oxo-2-aryltetrahydrofuran-3-yl)propanoates. The reaction of zinc enolates obtained from dimethyl 4-bromo-2,2-dimethyl-3-oxoheptane-1,7-dioate and zinc with aromatic aldehydes depending on the synthesis conditions led to the formation either methyl 2,2-dimethyl-3-oxo-3-(6-oxo-2-aryltetrahydropyran-3-yl)propanoates or 3-(5,5-dimethyl-4,6-dioxo-2-aryltetrahydropyran-3-yl)propanoates. The compounds synthesized formed as a single diastereomer of E-configuration.     

Hydrohalogenation of <Emphasis Type="Italic">N</Emphasis>-[arylsulfonylimino(phenyl)methyl]-1,4-benzoquinone monoimines having alkyl substituents in the quinoid ring

Hydrohalogenation of N-[arylsulfonylimino(phenyl)methyl]-2,5(3,5)-dimethyl-1,4-benzoquinone monoimines follows exclusively the 1,4-addition pattern, whereas N-[arylsulfonylimino(phenyl)methyl]-2,6-dimethyl-1,4-benzoquinone monoimines take up hydrogen halides according to the 6,3-addition scheme.     

Synthesis of novel dihydrothiazolo[3,2-a]pyrimidinone derivatives

Condensation of 2-amino-4-hydroxy-2-mercaptopyrimidine (2) hydrate and ethyl 4-bromocrotonate gave a mixture of ethyl 7-amino-2,3-dihydro-5-oxo-5H-thiazolo[3,2-a]pyrimidine-3-acetate (4) and 2a,3-dihydro-1-thia-5,8,8b-triazaacenaphthylene-4,7(2H)-dione (5) whereas reaction of 2 with 4-bromocrotononitrile afforded only 7-amino-2,3-dihydro-5-oxo-5H-thiazolo[3,2-a] pyrimidine-3-acetonitrile. Reaction of the tricycle 5 (which was isolated as a hemihydrate) with excess methyl iodide/potassium carbonate in dimethylformamide resulted in both ring hydrolysis and methylation to give 3,4-dihydro-1,7-dimethyl-4- [(methylthio)methyl]-2H-pyrimido[1,6-a]pyrimidine-2,6,8(1H,7H)-trione (10). Methylating 5 with excess methyl iodide/sodium methoxide in methanol also resulted in ring fragmentation and methylation but instead afforded methyl 7-methyl-amino-2,3-dihydro-5-oxo-7H-thiazolo[3,2-a]pyrimidine-3-acetate. The mechanistic aspects of these reactions are discussed.     

Synthesis of 1,4-Dihydropyrano[2,3-<Emphasis Type="Italic">c</Emphasis>]pyrazole Derivatives

In reaction of 2-(2-thienyl)- and 2-(2-furyl)acrylonitriles with 3-methyl-1-phenyl-5-pyrazolone in the presence of basic catalysts 4-thienyl- and 4-furyl derivatives of 3,5-dimethyl-1,7-diphenyl-4,8-dihydropyrano-[2,3-c, 5,6-c]dipyrazole were obtained.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 756–758.Original Russian Text Copyright © 2005 by Vasyun’kina, Bykova, Plotkin, Ramsh.     

Facile microwave-assisted synthesis of bis-pyrazol pyrimidine derivatives via an <Emphasis Type="Italic">N</Emphasis>-alkylation reaction

Abstract  

We present herein a new and efficient method for synthesis of bis-pyrazol pyrimidine derivatives by N-alkylation using a microwave-assisted synthetic process. Two new compounds, N-(4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)methyl nicotinonitrile and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-4-methyl nicotinonitrile, were synthesized by the N-alkylation reaction. The novel compounds were characterized by Fourier transform infrared spectrometry, ultraviolet spectroscopy, elemental analysis, and nuclear magnetic resonance spectroscopy, etc. The microwave-assisted procedures have noteworthy advantages in terms of thermal efficiency over those carried out by conventional heating methods.     

Synthesis of methyl 12-aryl-9,9-dimethyl-11-oxo-7,8,9,10,11,12-hexahydrobenzo[<Emphasis Type="Italic">a</Emphasis>]acridine-10-carboxylate

A three-component condensation of 2-naphthylamine, aromatic aldehydes, and methyl 2,2-dimethyl-4,6-dioxocyclohexanecarboxylate afforded methyl (cis,trans)-12-aryl-9,9-dimethyl-11-oxo-7,8,9,10,11,12-hexahydrobenzo[a]acridine-10-carboxylates. Spectral luminescence and nonlinear optical properties of compounds obtained were investigated.     

Spirobisheterocyclization of 5-(Methoxycarbonyl)-1<Emphasis Type="Italic">H</Emphasis>-pyrrol-2,3-diones by the action of enaminoesters. Crystal and molecular structure of 1,7-diazaspiro[4.4]nonane

1-Aryl-4-aroyl-5-(methoxycarbonyl)-1Н-pyrrole-2,3-diones react with methyl 4-aryl-2-(arylamino)-4-oxobut-2-enoates with the formation of methyl 1,7-diaryl-4,9-diaroyl-3-hydroxy-2,6-dioxo-1,7-diazaspiro[4.4]nona-3,8-diene-8-carboxylates.     

Borohydride reduction of acetophenone and esters of dehydrocarboxylic acids in the presence of chiral cobalt(<Emphasis Type="SmallCaps">II</Emphasis>) diamine complexes

The catalytic reduction of acetophenone, methyl α-acetamidocinnamate, and dimethyl itaconate with alcohol-modified sodium borohydride was studied in the presence of complexes CoCl₂·L₂ (L₂ are chiral C ₂-symmetric diamines: (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(diphenylaminomethyl)-1,3-dioxolane). The maximum enantiomeric excess of (S)-1-phenylethanol was 24%, that of dimethyl α-methylsuccinate was 38%.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–347, February, 2005.     

Poly(<Emphasis Type="Italic">N</Emphasis>-vinylimidazole) as an efficient and recyclable catalyst of the aza-Michael reaction in water

Poly(N-vinylimidazole) effectively catalyzed Michael addition of 1H-1,2,4-triazole, 3,5-dimethyl-1H-1,2,4-triazole, uracil, oxazolidin-2-one, and succinimide to but-3-en-2-one, cyclohex-2-en-1-one, methyl acrylate, and methyl vinyl sulfone in water at room temperature. The catalyst can readily be regenerated and repeatedly used at least five times without loss in activity, as shown in the reaction of 1H-1,2,4-triazole with but-3-en-2-one as an example.     

Napthyridines. IV. Synthesis of benzo[f]-1,7-naphthyridines

Benzo[f]-1,7-naphthyridines have been synthesized from 3-nitrolepidine ( 3 ) by a sequence involving monobromination of the methyl group of 3 , oxidation of the bromomethyl group to the carboxyladehyde group by Franzen's trimethylamine N-oxide procedure, and conversion of the resultant 3-nitro-1-quinoline-carboxaldehyde ( 6 ) to the benzo[f]-1,7-naphthyridine by the Borsche modification of the Friedlander cyclization.     

Rearrangement of benzylsulfanyl-substituted 2-aza-1,3,5-triene into 5-phenyl-4,5-dihydro-1,3-thiazole in the t-BuOK-THF-DMSO system

Benzylsulfanyl-substituted 2-aza-1,3,5-triene prepared according to one-pot procedure from methoxyallene, isopropyl isothiocyanate, and benzyl bromide underwent unexpected rearrangement in the superbasic t-BuOK-THF-DMSO system with formation of 2-[(Z)-1-methoxyprop-1-en-1-yl]-4,4-dimethyl-5-phenyl-4,5-dihydro-1,3-thiazole via α-deprotonation of the benzylsulfanyl substituent, followed by intramolecular [1,5]-cyclization. Concurrent deprotonation of methyl group in the ketone imine fragment and subsequent [1,7]-electrocyclization of the resulting azatriene carbanion afforded 2-(benzylsulfanyl)-3-methoxy-7-methyl-4,5-dihydro-3H-azepine and 6-methoxy-2-methyl-3H-azepine.     

Synthesis of a novel cyclodextrin dimer linked by a macrocyclic polyamine

The first example of cyclodextrin dimer appending a macrocyclic polyamine spacer on the primary faces was synthesized via two approaches: 1,a direct reaction of l,7-bis(2'-aminoethyl)-4,10-dimethyl-l,4,7,10-tetraazacyclododecane (1) with an excess of 6-deoxy-6-O-tosyl-β-cyclodextrin; 2,a condensation of 1 with two equivalents of 6-deoxy-6-formyl-β-cyclodextrin,which was followed by a reduction with NaBH4.     

Condensed pyridazines. Part III. Rearrangement and ring cyclization during the thermolysis of (z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate

The thermolysis of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate ( II ) provides a new synthetic route to pyrrolo[2,3-c-]pyridazines, specifically, methyl 3-chloro-1,6-dimethyl-4-oxo-1,4-dihydro-7H-pyrrolo[2,3-c]pyridazine-5-carboxylate ( III ) in 91% yield. Treatment of III with ozone provides an entry into the novel pyridazino[3,4-d][1,3]oxazine ring system, specifically, 3-chloro-1,7-dimethylpyridazino[3,4-d][1,3]oxazine-4,5-dione ( IV ) in 73% yield. Compound IV is smoothly hydrolyzed into 6-acetylamino-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazine-5-carboxylic acid ( V ) which is readily recyclized into IV by dehydration with acetic anhydride. Furthermore, IV undergoes a facile reductive ring opening reaction with sodium borohydride to give 3-chloro-6-ethylamino-1-methyl-4-oxo-1,4-dihydropyridazine-5-carboxylic acid ( VI ) in 95% yield.     

Regioselective synthesis of polyfluoroalkyl-substituted 7-(1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-1-yl)-6,7-dihydro-1<Emphasis Type="Italic">H</Emphasis>-indazol-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

3-Polyfluoroalkyl-6,6-dimethyl-7-(1H-1,2,3-triazol-1-yl)-6,7-dihydro-1H-indazol-4(5H)-ones were synthesized with high regioselectivity by 1,3-dipolar cycloaddition of terminal alkynes (phenylacetylene, hex- 1-yne, hept-1-yne, and but-3-yn-1-ol) to 7-azido-6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones which were prepared by bromination of 6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol- 4(5H)-ones with N-bromosuccinimide in anhydrous carbon tetrachloride, followed by treatment of the corresponding 7-bromo derivatives with sodium azide.     

3,3′‐Dimesityl‐7‐methyl‐9a‐phenyl‐4,4′,5,5′,6,8,9,9a‐octa­hydro‐7H‐1,2,4‐oxa­diazo­lo­[4,5‐d][1,4]­diazepine‐8‐spiro‐5′‐isoxazole

Condensation of mesito­nitrile oxide with 1,7‐di­methyl‐5‐phenyl‐2,3‐di­hydro‐1H‐1,4‐diazepine leads to two cycloadducts (I) and (II). The structure and stereochemistry of the dicyclo­adduct (II) was established by X‐ray crystallographic analysis.     

Synthesis of 1-substituted (R,S)-8-(2-methoxy-5-methylphenyl)-3,3,9-trimethyl-2-azaspiro[4.5]deca-1,7-dien-6-ones

Reactions between p-methylanisole, isobutyraldehyde, and nitriles (acetonitrile, methyl thiocyanate, or ethyl cyanoacetate) in conc. H₂SO₄ yield 1-substituted (R,S)-8-(2-methoxy-5-methylphenyl)-3,3,9-trimethyl-2-azaspiro[4.5]deca-1,7-dien-6-ones.     

Neomacrodione: a new degraded diterpenoid from the roots of Neoboutonia macrocalyx Beng (Euphorbiaceae)

One new degraded diterpenoid 3,6-dihydroxy-1,7-dimethyl-9,10-phenantroquinone (neomacrodione) (1) together seven known compounds were isolated from the roots of Neoboutonia macrocalyx (Euphorbiaceae). The structures of the compounds were established based on their NMR and mass spectrometric data in conjunction with those previously reported in the literature. Compound (1) displayed moderate antibacterial activities.     

The structure of covalent hydrates of alloxazines. A reinvestigation

It is shown by ¹³C-NMR. and synthesis of 6,7-dimethyl-3-ethoxycarbonylamino-quinoxaline-2-carboxamide ( 5 ) and methyl 6,7-dimethyl-3-(N′-methylureido)-quinoxaline-2-carboxylate ( 6 ) that hydrolysis of lumichrome ( 1 , R = H) must yield 6,7-dimethyl-3-ureidoquinoxaline-2-carboxylic acid ( 2 , R = H) and not 6,7-dimethyl-2-oxo-1,2,9,9a-tetrahydrooxazolo[4,5-b]quinoxaline-9a-carboxamide ( 2a , R = H), as previously proposed.