Formation of fluorene and anthracene derivatives in reactions of perfluorinated 1-alkyl-1-phenyl- and 1-alkyl-2-phenyl-1,2-dihydrocylobutabenzenes with antimony pentafluoride

The reaction of perfluoro(1-methyl-1-phenyl-1,2-dihydrocyclobutabenzene) with SbF₅ at 50°C, followed by hydrolysis, gave perfluoro(1-phenylindan-1-ol), while analogous reaction at 90°C afforded perfluoro[10-methylanthracen-9(10H)-one]. Perfluoro(1-methyl-2-phenyl-1,2-dihydrocyclobutabenzene) did not undergo skeletal transformations under analogous conditions, whereas at 200°C it was converted mainly into perfluoro(9-methylfluoren-9-ol). Perfluoro(1-ethyl-2-phenyl-1,2-dihydrocyclobutabenzene) reacted with SbF5 at 200°C to form perfluoro(9-ethylfluoren-9-ol) together with perfluorinated 9,9-dimethyl- and 9-ethyl-9-methyl-1,2,3,4-tetrahydro-9H-fluorenes.     

Transformations of Perfluorinated 2-Alkyl- and 2,2-Dialkylbenzocyclobutenones in SbF<Subscript>5</Subscript> and SiO<Subscript>2</Subscript>-SbF<Subscript>5</Subscript>

Perfluorinated 2-methyl- and 2-ethylbenzocyclobutenones on heating in SbF₅ underwent isomerization into perfluoroindan-1-one and perfluoro(2-methylindan-1-one), while their reaction with SiO₂—SbF₅ gave perfluorinated 3-methyl- and 3-ethylphthalides, respectively. Perfluorinated 2-ethyl-2-methyl- and 2,2-diethylbenzocyclobutenones reacted with SbF₅ to produce perfluorinated 2-(but-2-en-2-yl)- and 2-(pent-2-en-3-yl)-benzoic acids, and their transformations in SbF₅ over SiO₂ afforded 5,6,7,8-tetrafluoro-1-oxo-3-trifluoromethyl-1H-isochromene-4-carboxylic acid and perfluoro(4-ethyl-3-methyl-1H-isochromen-1-one), respectively.     

Expansion of the pentafluorobenzene ring and other skeletal transformations in the reaction of perfluoro(1,2-diethyl-1-phenyl-1,2-dihydrocyclobutabenzene) with antimony pentafluoride

The reaction of perfluoro(1-phenyl-1,2-diethyl-1,2-dihydrocuclobutabenzene) with SbF5 at 20°C, followed by treatment of the reaction mixture with water gave perfluoro {4-[1-(2-propylphenyl)propylidene]-2,5-cyclohexadien-1-one} together with perfluoro[4b,10-diethylbenzo[a]azulen-7(4bH)-one] resulting from unusual expansion of the pentafluorobenzene ring to seven-membered ring. Analogous reaction at 90°C, apart from the above compounds, afforded perfluorinated 10-ethyl- and 3,10-diethylbenzo[a]azulen-6(10H)-ones via elimination of C₂F₅ group from the seven-membered ring or its migration to the benzene ring.     

Skeletal transformations of pentafluorophenylation products of perfluorinated 1,2-dialkyl-1,2-dihydrocyclobutabenzenes in SbF5

Perfluorinated 1-ethyl-2-methyl- and 1-isopropyl-2-methyl-1,2-dihydrocyclobutabenzenes reacted with pentafluorobenzene in SbF₅ to generate perfluoro(1-ethyl-2-methyl-2-phenyl- and perfluoro(1-izopropyl-2-methyl-2-phenyl-1,2-dihydrocyclobutabenzen-1-yl) cations. These cations in SbF₅ at 20°C underwent opening of the four-membered ring and its expansion to five-membered. After hydrolysis, perfluorinated 4-[1-(2-propylphenyl)ethylidene]- and 4-[1-(2-isobutylphenyl)ethylidene]-2,5-cyclohexadien-1-ones were obtained together with perfluoro(3-ethyl- and perfluoro(3-isopropyl-2-phenylinden-1-ones).     

Reactions of perfluorinated 1-ethyltetrahydronaphthalene, 1-ethylindan, and 1,1-diethylindan with pentafluorobenzene in antimony pentafluoride

The reaction of perfluoro(1-ethyltetrahydronaphthalene) with pentafluorobenzene in SbF₅, followed by treatment of the reaction mixture with water, afforded a mixture of 1-hydroxyperfluoro(1-phenyl-4-ethyletetrahydronaphthalene) and perfluoro(5-phenyl-8-ethyl-2,6,7,8-tetrahydronaphthalen-2-one). From perfluoro(1,1-diethylindan), 1-hydroxyperfluoro(1,1-diethyl-3-phenylindan) was obtained. Perfluoro(1-ethylindan) reacted with an equimolar amount of pentafluorobenzene in SbF₅ to give (after hydrolysis) 1-hydroxyperfluoro-(3-ethyl-1-phenylindan), 1-hydroxyperfluoro(3-ethyl-1,3-diphenylindan), and perfluoro(1-ethyl-1-phenylindan), while in the reaction with excess pentafluorobenzene, followed by treatment with anhydrous hydrogen fluoride, perfluoro(1-ethyl-3-phenylindan) and perfluoro(1-ethyl-1,3-diphenylindan) were formed.     

X-ray diffraction investigation of perfluoro-4-methylenecyclohexa-2,5-dienones

Perfluorinated 8-phenyl-7,8-diethylbicyclo[4.2.0]octa-1,4,6-trien-3-one (3), 2-(4-oxocyclohexa-2,5-dienylidene)-1,1-diethylbenzocyclobutene (4) and 2-(4-oxocyclohexa-2,5-dienylidene)-5-(2-phenyl-cis-1,2-diethylbenzocyclobuten-1-yloxy)-1,1-diethylbenzocyclobutene (5), including the 4-methylencyclohexa-2,5-dienone fragment, were prepared by the reaction of perfluoro-1,1-(1) and-1,2-diethylbenzocyclobutene (2) with pentafluorobenzene in SbF₅. Single crystal X-ray diffraction study of compounds 3–5 revealed that the oxygen atom of the C=O group participated in the formation of supramolecular architectures in all three compounds, and C=O…π bonding may be considered as the corresponding synthon (with increased separation in the case of compound 5). C-F…π bonding acts as a second synthon. F…F interactions in crystals 3–5 were classified as stabilizing or enforced.     

Opening of the four-membered ring in perfluorinated 1-alkyl-2-phenyl- and 1-aryl-1,2-dihydrocyclobutabenzenes in the system I<Subscript>2</Subscript>-SbF<Subscript>5</Subscript>

Reactions of perfluorinated 1-phenyl-, 1-(2-ethylphenyl)-, 1-(4-ethylphenyl)-, 1-methyl-2-phenyl-, and 1-ethyl-2-phenyl-1,2-dihydrocyclobutabenzenes with iodine in antimony pentafluoride at 130°C, followed by hydroysis of the reaction mixture, resulted in the formation of perfluorinated 2-methyl-, 2-ethyl-2′-methyl-, 4-ethyl-2′-methyl-, 2-ethyl-, and 2-propylbenzophenones via opening of the four-membered ring in the initial cyclobutabenzene at the C¹–C² bond. The presence of hydrogen fluoride facilitates the process and promotes profound transformations leading to anthracene derivatives.     

New derivatives of 4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrazole, 4,5-dihydro-1,2-oxazole,and pyrimidine prepared proceeding from (<Emphasis Type="Italic">E</Emphasis>)-3-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-one

Condensation of acetylferrocene with 5-phenyl(4-methylphenyl)-1,2-oxazole-3-carbaldehydes afforded (Е)-3-[5-phenyl(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-ones. Reactions of (Е)-3-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-one with semicarbazide, thiosemicarbazide, and hydroxylamine led to the formation of 5-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-3-ferrocenyl-4,5-dihydro-1H-pyrazole- 1-carboxamide, 5-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-3-ferrocenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide, and 5-(4-methylphenyl)-3'-ferrocenyl-4',5'-dihydro-3,5'-bi-1,2-oxazole respectively. Reactions of (Е)-3-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-one with guanidine and thiourea result in 4-[5-(4-methyl-phenyl)-1,2-oxazol-3-yl]-6-ferrocenylpyrimidin-2-amine and -2-thione respectively.     

Unusual formation of 7-vinylcycloheptatriene derivatives in the catalytic cyclopropanation of cyclooctatetraene with diazocarbonyl compounds in the presence of rhodium catalysts

The reaction of cyclooctatetraene with methyl diazoacetate or diazoacetone in the presence of rhodium binuclear complexes gives, besides 9-substituted bicyclo[6.1.0]nona-2,4,6-trienes (mixture ofanti- andsyn-isomers, total yields 60–75%), isomeric β-(cyclohepta-2,4,6-trien-1-yl)acrylates or 4-(cyclohepta-2,4,6-trien-1-yl)but-3-en-2-one in 20–34% yields. In the case of methyl diazoacetate, a mixture ofE- andZ-isomers in a ratio of −3.5∶1 was obtained, while diazoacetone gave onlyE-isomer. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2204–2206, November, 1999.     

Control of photoreactions of eight membered ring di- and trienones in a crystalline inclusion complex with optically active 1,6-DI(o-Chlorophenyl)-1,6-diphenylhexa-2,4-diyne-1,6-diol

By complexing with the title host compound, flipping equilibrium of cycloocta-2,4,6-trien-1-one was frozen in one optical conformer as a 2:1 complex, which upon irradiation gave optically active bicyclo [4.2.0] octa-4,7-dien-2-one. Irradiation of a 1:2 complex of cycloocta-2,4-dien-1-one and the same host compound gave an optically active dimer, anti-tricyclo [8.6.0.0^2,9] hexadeca-7, 11-diene-3, 16-dione.     

Unusual reaction of chloroacetyl chloride with 1,2-dichloroethene. Synthesis and properties of 2-chlorovinyl dichloromethyl ketone

The reaction of chloroacetyl chloride with 1,2-dichloroethene in the presence of AlCl₃ unexpectedly led to the formation of (E)-1,1,4-trichlorobut-3-en-2-one whose structure was proved by ¹H and ¹³C NMR, IR, and mass spectra and independent synthesis. A probable reaction scheme was proposed, which involves transformation of initially formed 1,2,4-trichloro-3-oxobutan-2-yl cation by the action of AlCl₃. The high reactivity of the vinylic halogen atom in (E)-1,1,4-trichlorobut-3-en-2-one was demonstrated by its reactions with nitrogen-centered nucleophiles (triethylamine, aniline, 3,5-dimethyl-1H-pyrazole) and sodium sulfide. These reactions involved only the C-Cl bond in the vinyl fragment and afforded (4,4-dichloro-3-oxobut-2-en-1-yl)triethylammonium chloride, 1,1-dichloro-4-phenylaminobut-3-en-2-one, 1-(4,4-dichloro-3-oxobut-2-en-1-yl)-3,5-dimethyl-1H-pyrazole, and 4,4′-thiobis(1,1-dichlorobut-3-en-2-one), respectively. The reaction of 1,1,4-trichlorobut-3-en-2-one with benzylhydrazine gave a mixture of 1,3- and 1,5-disubstituted pyrazoles.     

Two New Sequiterpenoids from Helicteres angustifolia

A new sesquiterpenoid lactone, 3,6,9-trimethyl-pyrano[2,3,4-de]chromen-2-one (1) and a novel sesquiterpenoid quinone, 6-[2-(5-acetyl-2,7-dimethyl-8-oxo-bicyclo[4.2.0]octa-l,3,5-trien-7-yl)-2-oxo-ethyl]-3,9-dimethylnaphtho[1,8-bc]pyran-7,8-dione (2) together with a known perezone (3) were isolated from the roots of Helicteres angustifolia. The structures were elucidated as mainly on the basis of ID and 2D NMR spectroscopic data.     

Three-Component Spiro Heterocyclization of Pyrrolediones with Indan-1,3-dione and Acyclic Enamines

Ethyl 4,5-dioxo-2-phenyl-4,5-dihydro-1H-pynole-3-carboxylates reacted with indan-1,3-dione and 3-amino-1-phenylbut-2-en-1-one or 3-aminobut-2-enenitrile to give 3-benzoyl-2-methyl-2′,5-dioxo-5′-prienyl-1,1′,2′,5-tetrahydrospiro[indeno[1,2-b]pyridine-4,3′-pyrroles] and 2-methyl-2′,5-dioxo-5′-phenyl-1,1′,2′,5-tetrahydrospiro[indeno[1,2-b]pyridine-4,3′-pyrrole]-3-carbonitriles, respectively.

     

Derivatives of α,β-dehydro amino acids: VI. Reaction of 4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-one with piperidin-2-ylmethanamine

4-Benzylidene-2-phenyl-1,3-oxazol-5(4H)-one reacts with piperidin-2-ylmethanamine to give N-{(Z)-3-oxo-3-[(piperidin-2-ylmethyl)amino]-1-phenylprop-1-en-2-yl}benzamide, N-(4-benzyl-3-oxooctahydro-2N-pyrido[1,2-a]pyrazin-4-yl)benzamide, or/and (Z)-4-benzylidenehexahydro-2H-pyrido[1,2-a]pyrazin-3(2H)-one, depending on the solvent, temperature, and reaction time. The latter product is formed via three-step tandem process.     

Reaction of 1,3,4,6-tetraketones with <Emphasis Type="Italic">p</Emphasis>-toluidine and benzaldehyde

Reactions of 1,6-diphenylhexane-1,3,4,6-tetraone, octane-2,4,5,7-tetra-one, and decane-3,5,6,8-tetraone with a mixture of p-toluidine and benzaldehyde afforded, respectively, 2-[4-benzoyl-3-hydroxy-1-(4-methylphenyl)-5-phenyl-1H-pyrrol-2-yl]-1-phenylethanone, (1E)-1-[4-acetyl-3-hydroxy-1-(4-methylphenyl)-5-phenyl-1,5-dihydro-2H-pyrrol-2-ylidene]propan-2-one, and 2-hydroxy-1-(4-methylphenyl)-2-(2-oxobutyl)-4-propanoyl-5-phenyl-1,2-dihydro-3H-pyrrol-3-one.     

Dipolar additions with 1-(4,6-dimethylpyrimidin-2-yl)- and 1-(4,6-dimethoxy-s-triazin-2-yl)-3-oxidopyridinium betaines

Cycloaddition to 1-(4,6-dimethylpyrimidin-2-yl)- and 1-(4,6-dimethoxy-s-triazin-2-yl)-3-oxidopyridinium betaines across the 2,6-positions of the pyridine rings with indene, acenaphthylene and ethyl cinnamate gave substituted 8-aza[3.2.1]bicycIooct-3-en-2-ones, whereas the [6π + 4π] cycloaddition reaction with 6,6-dimethylfulvene gave a tricyclo[6.3.1.0^2.6]dodeca-2,(6),4,9-trien-11-one. Structural and configurational assignments of the cycloadducts were deduced from ¹H nmr and ir spectral data.     

Thermal decomposition of 2-amino-3-aziridino-1,4-naphthoquinones

The course of the thermal decomposition of various 2-amino-3-substituted aziridino-1,4-naphthoquinones (Ia-g) was investigated. In all the cases, the thermal decomposition gave variable amounts of 2,3-diamino-1,4-naphthoquinone (II) and of substituted 1,2,3,4,5,10-hexahydrobenzo[g]quinoxaline-5,10-diones (IIIa-g) with complete stereospecificity. The decomposition of the aziridines Ib,f also gave significative amounts of 2-amino-3-allylamino-1,4-naphthoquinones (IVb,f). In the case of 2-amino-3-(2′-phenyl-3′-ethylaziridino)-1,4-naphthoquinone (Ig), the formation of trans-1-phenyl-1-butene (V), 2-(1-phenylpropyl)-1H-naphtho-imidazole-4,9-dione (VI), 2-phenyl-3-ethyl-3,4,5,10-tetrahydrobenzo[g]quinoxaline-5,10-dione (VII), 2-phenyl-3-ethyl-5,10-dihydrobenzo[g]quinoxaline-5,10-dione (VIII), and a mixture of cis- and trans-4H-2,3,5,6-tetra-hydro-2-phenyl-3-ethyl-5-iminonaphtho[1,2-b]oxazin-6-one (IX) also occurred. Hypotheses concerning the mechanism and the steric course of this reaction are given. The reaction is a general method for the stereospecific synthesis of 2,3-disubstituted 1,2,3,4,5,10-hexahydrobenzo[g]quinoxalines.     

Photoreactions of 3-diazo-3H-benzofuran-2-one; dimerization and hydrolysis of its primary photoproduct, a quinonoid cumulenone: a study by time-resolved optical and infrared spectroscopy

Light-induced deazotization of 3-diazo-3H-benzofuran-2-one (1) in solution is accompanied by facile (CO)-O bond cleavage yielding 6-(oxoethenylidene)-2,4-cyclohexadien-1-one (3), which appears with a rise time of 28 ps. The expected Wolff-rearrangement product, 7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-ylidenemethanone (4), is not formed. The efficient light-induced formation of the quinonoid cumulenone 3 opens the way to determine the reactivity of a cumulenone in solution. The reaction kinetics of 3 were monitored by nanosecond flash photolysis with optical (lambda(max) approximately 460 nm) as well as Raman (1526 cm(-1)) and IR detection (2050 cm(-)(1)). Remarkably, the reactivity of 3 is that expected from its valence isomer, the cyclic carbene 3H-benzofuran-2-one-3-ylidene, 2. In aqueous solution, acid-catalyzed addition of water forms the lactone 3-hydroxy-3H-benzofuran-2-one (5). The reaction is initiated by protonation of the cumulenone on its beta-carbon atom. In hexane, cumulenone 3 dimerizes to isoxindigo ((E)-[3,3']bibenzofuranylidene-2,2'-dione, 7), coumestan (6H-benzofuro[3,2-c][1]benzopyran-6-one, 8), and a small amount of dibenzonaphthyrone ([1]benzopyrano[4,3-][1]benzopyran-5,11-dione, 9) at a nearly diffusion-controlled rate. Ab initio calculations (G3) are consistent with the observed data. Carbene 2 is predicted to have a singlet ground state, which undergoes very facile, strongly exothermic (irreversible) ring opening to the cumulenone 3. The calculated barrier to formation of 4 (Wolff-rearrangement) is prohibitive. DFT calculations indicate that protonation of 3 on the beta-carbon is accompanied by cyclization to the protonated carbene 2H(+), and that dimerization of 3 to 7 and 9 takes place in a single step with negligible activation energy.     

Two-dimensional correlation NMR study of the structure of by-product in the reaction of 2-methylquinoline with 3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2-benzoquinone

The reaction of 2-methylquinoline with 3,5-di-tert-butyl-1,2-benzoquinone afforded a mixture of 5,7-di-tert-butyl-3-hydroxy-2-(quinolin-2-yl)cyclohepta-2,4,6-trien-1-one and previously unknown 10-tert-butylindolo[1,2-a]quinoline-8,11-dione. The structure of the latter was determined by two-dimensional heteronuclear correlation NMR spectroscopy.     

Self-cyclization of (E)-2-(trimethylsilylmethyl)pentadienol derivative. Synthesis of bicyclo[4.3.0]nonane ring systems

Utility and limitation of the title reaction was studied. When (E)-3-(4-t-butyl- and 4-phenylcyclohex-1-en-1-yl)-2-(trimethylsilylmethyl)prop-2-en-1-ols were treated with Ms₂O or MsCl, 3-t-butyl- and 3-phenyl-8-methylbicyclo[4.3.0]nona-1(6),7-dienes were obtained, respectively. The corresponding (Z)-isomer afforded a complex mixture, among which an elimination product was detected. (E)-4-(4-t-Butylcyclohexylidene)-2-(trimethylsilylmethyl)but-2-en-1-ol afforded only elimination product.