4-alkyl(aryl)-1-germacyclohexa-2,5-diene

enThe 1(Z),4(Z)-1,5-dilithium-3R-3-methoxypenta-1,4-dienes react with diaryldichlorogermanes and dialkyldichlorogermanes to give the 1,1-diaryl- and 1,1-dialkyl-4R-4-methoxy-1-germacyclohexa-2,5-dienes, respectively.With phenyltrichlorogermane, methyl- and ethyl-trichlorogermanes the E/Z-isomeric 1-phenyl(methyl,ethyl)-1-chloro-4R-4-methoxy-1-germacyclohexa-1,3-dienes are obtained, reduction of these with LiAlH₄ makes the corresponding 1-aryl-(alkyl)-1H-4R-4-methoxy-1-germacyclohexa-2,5-dienes available.Reduction of 1-ethyl-1-chloro-4-phenyl-4-methoxy-1-germacyclohexa-2,5-diene with LiAlH₄ yields by additional ether cleavage 1-ethyl-1H-4-phenyl-1-germacyclohexa-2,4-diene.The ¹H NMR (60 MHz, 90 MHz), ¹³C NMR, IR and mass spectra are discussed, several ¹H NMR spectra are calculated according to the LAOCOONLAME program.     

Synthese und chemie von 4R-silacyclohexa-2,5-dienen und 4R-silacyclohexa-2,4-dienen

The 1(Z),4(Z)-1,5-dilithium-3R-3-methoxypenta-1,4-dienes, available by cleavage of 1,1-di-n-butyl-4R-4-methoxy-1-stannacyclohexane-2,5-dienes with n-BuLi in ether, react with dichlorosilanes (R′R″ SiCl₂; R′, R″ = H, alkyl, aryl, alkoxy) to give 1R′,1R″,4R-4-methoxy-1-silacyclohexa-2,5-dienes.Claevage of the ether group with BBr₃, BCl₃ or PCl₃ gives 6-chloro(bromo)-1-silacyclohexa-2,4-dienes or 1,5-dichloro-1-silacyclohexane-2,4-dienes, respectively.Ether cleavage of 4R-4-methoxy-1-silacyclohexa-2,5-dienes with sodium results in the formation of 4R-1-silacyclohexadienyl anions, which can be hydrolyzed to give 1-silacyclohexa-2,4-dienes which reach further with trichloromethylsilane to give 6-trimethylsilyl-1-silacyclohexa-2,4-dienes.Phase transfer-catalyzed conversion of 1-chlorosilacyclohexadienes into the fluoro derivatives as well as further substitution reactions of 1-chlorosilacyclohexadienes are described.The ¹H NMR, ¹³C NMR, IR and mass spectra of the silacyclohexadienes are discussed.     

Silacyclohexadienylanionen bis- und tris-trimethylsilyl)-silacyclohexadiene

1,1-Dialkyl(1,1-diaryl)-4-R-1-silacyclohexadienyl anions (1) are available by ether cleavage of the corresponding, 1,1-dialkyl(1,1-diaryl)-4-methoxy-4-R-1-silacyclohexa-2,5-dienes (4), or by deprotonation of the 1,1-dialkyl(1,1-diaryl)-4-R-1-silacyclohexa-2,4-dienes (3) - which are available from 4 - with n-BuLi or LDA resp.The anions 1 are regioselectively silylated by trimethylchlorosilane to give the 6-trimethylsilyl-1-silacyclohexa-2,4-dienes (7,8), their alkylation or acylation occurs exclusively in 4-position to 16 or 17 resp.Deprotonation of 7, 8 with n-BuLi gives the 2-trimethylsilyl-1-silacyclohexadienyl (9), with trimethylchlorosilane they react regioselectively to give the 2,6-bis(trimethylsilyl)-1-silacyclohexa-2,4-dienes (10, 11), with alkyl halides and ketones the anion 9 reacts only in the 4-position.The 1-silacyclohexa-2,5-dienes 22, 25, 28 substituted at the silicon atom by functional groups (O-i-Prop) or by hydrogen can be transformed into 2,6-bis(trimethylsilyl)-1-silacyclohexa-2,4-dienes 24, 27, 33 resp., if LDA is used as base.The easily formed 4-R-2,6-bis(trimethylsilyl)-1-silacyclohexa-2,4-dienyl anions (by deprotonation of 10, 11, 24, 27, 33 with LDA) react with trimethylchlorosilane regioselectively to give the 4-R-2,4,6-tris(trimethylsilyl)-1-silacyclohexa-2,5-dienes 37. Accessing 37 succeeds very simply by manifold-silylation of the 1-sila-2,4-cyclohexadienes 38 with excess trimethylchlorosilane in the presence of 3 mol LDA.Owing to trimethylsilyl substitution in the 2,6-position of the 1-silacyclohexa-2,4-dienes, the ring-silicon atom is strongly sterically shielded, therefore reactions of functional groups at the silicon atom are restricted.     

Reactions of Polyfluorinated 3-Substituted 2,4-Cyclohexadienones with Alkynes

Reactions of 2,3,4,5,6-pentafluoro-6-chloro-2,4-cyclohexadienone with anthranylic acid, 2,6-dichloro- and 2,6-dimethylaniline, diethylamine, sodium azide, and also the reaction of 6-phenyl-3-pentafluorophenoxy-2,4,5,6-tetrafluoro-2,4-cyclohexadienone with methanol afford 3-substituted 2,4,5,6-tetrafluoro-2,4-cyclohexadienones. The 3-methoxy-2,4,5,6-tetrafluoro-6-chloro-2,4-cyclohexadienone and 3-methoxy-6-phenyl-2,4,5,6-tetrafluoro-2,4-cyclohexadienone form cycloadducts with 1-hexyne and propargyl alcohol that under treatment with propyl alcohol in the presence of potassium carbonate undergo ring cleavage to furnish propyl arylfluorochloroacetates and diarylacetates. The reaction between 3-azido-2,4,5,6-tetrafluoro-6-chloro-2,4-cyclohexadienone and phenylacetylene gives rise to 4-oxo-2-phenyl-3,5,6,7-tetrafluoro-5-chlorobicyclo[4.1.0]hept-2-ene-7-carbonitrile.     

1,1-Dimethyl-1-silacyclohexa-2,4-dien-tricarbonyleisen Vorläufige Mitteilung

1,1-Dimethyl-2,3,4,5-tetraphenyl-1-silacyclohexa-2,4-diene is isomerized by iron pentacarbonyl to 1,1-dimethyl-2,3,4,5-tetraphenyl-1-silacyclohexa-2,5-diene. However, iron pentacarbonyl with 1,1-dimethyl-1-sila-cyclohexa-2,4-diene yields 1,1-dimethyl-1-silacyclohexa-2,4-diene-tricarbonyl-iron.     

Synthesis of new sulfanyl-, sulfinyl-, and sulfonyl-substituted polychlorobuta-1,3-dienes

New R-sulfanyl-substituted polychlorobuta-1,3-dienes were synthesized by reactions of hexachloro-1,3-butadiene or 1,1,2,4,4-pentachlorobuta-1,3-diene with dimethylbenzenethiols, heptane-1-thiol, and 4-methyl-7-sulfanyl-2H-chromen-2-one. Some sulfides were oxidized to the corresponding sulfoxides and sulfones or brominated with bromine. Among the synthesized compounds, the coumarin derivative, 4-methyl-7-(1,2,3,4,4-pentachlorobuta-1,3-dien-1-ylsulfanyl)-2H-chromen-2-one showed fluorescence properties. 1,1′,1″-[3,4-Dichlorobuta-1,3-diene-1,1,4-triyltris(sulfanediyl)]tris(2,4-dimethylbenzene) reacted with potassium tert-butoxide in petroleum ether to afford a mixture of isomeric 1,1′,1″-[4-chlorobuta-1,2,3-triene-1,1.4-triyltris(sulfanediyl)]tris(2,4-dimethylbenzene) and 1,1′,1″-[2-chlorobut-1-en-3-yne-1,1,4-triyltris(sulfanediyl)]-tris(2,4-dimethylbenzene). The GC/MS method was found to be useful for the separation of some sulfanyl-substituted butadiene isomer mixtures. The synthesized compounds were characterized by elemental analyses, mass spectrometry, UV-Vis, IR, and NMR (¹H, ¹³C) or fluorescence spectroscopy.     

Three-component reaction of methyl 2,4-dioxo-4-phenylbutanoate and methyl 2,4-dioxopentanoate with aromatic aldehydes and propane-1,2-diamine and chemical properties of the products

The reactions of methyl 2,4-dioxo-4-phenylbutanoate and methyl 2,4-dioxopentanoate with a mixture of an aromatic aldehyde and propane-1,2-diamine, depending on the initial reactant ratio, gave 4-acyl-1-(2-aminopropyl)-5-aryl-3-hydroxy-2,5-dihydro-1H-pyrrol-2-ones and 1,1′-(propane-1,2-diyl)bis(4-acetyl-3-hydroxy-5-phenyl-2,5-dihydro-1H-pyrrol-2-one). Reactions of substituted 1-(2-aminopropyl)-2,5-dihydro-1H-pyrrol-2-ones with aromatic amines and hydrazines were studied, and the structure of one of the products, 5-(2-aminopropyl)-3,4-diphenylpyrrolo[3,4-c]pyrazol-6-one, was proved by X-ray analysis.     

New method of synthesis of 1,1-bis(trialkylsilyl)- and bis(trialkylgermyl)germacyclopenta-2,4-dienes

The reactions of 1,1-dichloro-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene (1), magnesium, and R₃ECl (E = Si, Ge) under mild conditions (20 °C, THF) gave 1,1-bis(trimethylsilyl)-2,3,4,5-tetraphenyl-1-germacyclopenta-2,-4-diene (2a) and 1,1-bis(triethylgermyl)-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene (2b) respectively. The reaction is versatile and applies to the compounds R₃ECl (E = Si, Ge) that do not react with magnesium.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2234–2236, October, 2004.     

Synthesis of 2-amino-6-(nitroimidazolyl)thiopurines

We have synthesized a series of novel 2-amino-6-(nitroimidazolyl)thiopurines by reaction of thioguanine with 1-alkyl(1,2-dialkyl)-5-chloro-4-nitro-, 2-alkyl(1,2-dialkyl)-5-bromo-4-nitro-, and 1-alkyl(1,2-dialkyl)-4-chloro-5-nitroimidazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 221–224, February, 2000.     

Formation of bicyclic adducts in the reactions of fluorinated 2,4-cyclohexadien-1-ones with 2-carboxyhenzenediazonium

Benzyne generated during the decomposition of 2-carboxybenzenediazonium interacts with 6-chloro-2,3,4,5,6-pentafluoro-2,4-cyclohexadien-1-one, 6-chloro-2,4,5,6-tetrafluoro-3-methoxy-2,4-cyclohexadien-1-one, 6-chloro-2,4,5,6-tetrafluoro-3-(pentafluorophenoxy)-2,4-cyclohexadien-1-one, and perfluoro-6-phenoxy-2,4-cyclohexadien-1-one to form [4+2]-cycloaddition products. The latter are easily converted to 1-naphthylacetic acid derivatives by the action of O- and N-nucleophiles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1634–1637, September, 1994.This work was carried out with the financial support of the International Science Foundation (Project No. Ch₂-6713-0925).     

Substituierte 5-Hydroxypyrimidine und ihre O,O-Diethylphosphorsäure-, O,O-Diethylthiophosphorsäure-und N,N-Dimethylcarbamidsäureester

4-Alkyl (or aryl)-6-chloro-5-hydroxy-2-methylpyrimidines5a–5e, 4-alkyl (or aryl)-5-hydroxy-2-methyl-1H-pyrimidin-6-ones5g–5k and 6-alkyl (or aryl)-5-hydroxy-1H,3H-pyrimidin-2,4-diones5l–5n were prepared and converted into O,O-diethylphosphoric acid esters7a–7e, O,O-diethylphosphorothioic acid esters7f–7i and N,N-dimethylcarbamic acid esters8.

     

Reactions of 5-aminopyrimidines with phosphorus pentachloride

5-Amino-4, 6-dichloro-, 5-amino-4-chloro-6-methoxy-, and 5-amino-4-chloro-6-morpholinopyrimidines react with PCl₅ to form monomeric 5-(trichlorophosphoranyleneamino)pyrimidines.     

Novel route of the reaction of trifluoromethyl-containing N-methyl(4-ethoxyphenyl)imidazolidin-2-ones with urea

The reactions of perfluorobiacetyl with N-(4-ethoxyphenyl)- and N-methylurea afforded cis- and trans-isomers of 1-methyl-4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidin-2-one and 1-(4-ethoxyphenyl)-4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidin-2-one in a yield of ～60—75%. N-Alkyl(aryl)bis(trifluoromethyl)imidazooxazoles were obtained as unexpected products in the reaction of 1-alkyl(aryl)-4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidin-2-ones with urea in dimethylacetamide. The reaction is accompanied by the rearrangement of imidazolidin-2-ones to N-alkyl(aryl)-5,5-bis(trifluoromethyl)hydantoins with CF₃ group migration from position 5 to position 4 of the starting heterocycle. A similar rearrangement is observed on boiling of the studied imidazolidin-2-ones in dimethylacetamide. The molecular structures of 3-(4-ethoxyphenyl)-5,5-bis(trifluoromethyl)imidazolidine-2,4-dione and 6-(4-ethoxyphenyl)-3a,6a-bis(trifluoromethyl)tetrahydroimidazo[4,5-d]oxazole-2,5-dione were studied by X-ray diffraction analysis.     

5(4)-Chloro-1-(2,4-dinitrophenyl)pyrazoles from 2,4-Dinitrophenylhydrazones of Chlorovinyl Ketones and β,β-Dichloroacrolein

A method has been developed for obtaining 3-alkyl(phenyl)-4(5)-chloro-1-(2,4-dinitrophenyl)pyrazoles from appropriate dinitrophenylhydrazones of 1-chloro-, 1,2-, and 2,2-dichlorovinyl ketones by heating the latter in polyphosphoric acid. The structure of the pyrazoles was studied by IR and ¹H NMR spectroscopy. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1012–1019, July, 2005.     

Rearrangement of 1,4-benzodiazepin-2,4-diones to 3,l-benzoxazin-4-ones

Treatment of 7-chloro-3,4-dihydro-1H-1,4-benzodiazepin-2,5-dione (Ia) with refluxing acetic anhydride in the presence of pyridine afforded 6-chloro-2-methyl-4H-3,1-benzoxazin-4-one (IIa). A plausible reaction path for this novel rearrangement reaction is described: Ia → 4-acetyl-7-chloro-3,4-dihydro-lH-1,4-benzodiazepin-2,5-dione → 7-chloro-1,4-diacetyl-3,4-dihydro-lH-1,4-benzodiazepin-2,4-dione → IIa. When 7-chloro-3,4-dihydro-4-methyl-lH-1,4-benzodiazepin-2,5-dione (Ib), 3,4-dihydro-4-methyl-1H-1,4-benzodiazepin-2,5-dione (Id) and 3,4-dihydro-1-methyl-1H-1,4-benzodiazepin-2,5-dione (Ie) were allowed to react with acetic anhydride under conditions similar to those used for the rearrangement reaction, only acetylation occurred.     

Catalytic [6<Emphasis Type="Italic">π</Emphasis> + 2<Emphasis Type="Italic">π</Emphasis>]-Cycloaddition of 1,2-Dienes to Bis(cyclohepta-1,3,5-trien-7-yl)alkanes in the Presence of Ti(acac)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>,–Et<Subscript>2</Subscript>AlCl

An efficient procedure has been developed for the synthesis of difficultly accessible 9,9′-(alkane-α,ω-diyl)bis[7-(diphenylmethylidene)bicyclo[4.2.1]nona-2,4-dienes] and 16,16′-(alkane-α,ω-diyl)bis(tricyclo-[9.4.1.0^2,10]hexa-2,12,14-trienes) in 55–84% yields by [6π + 2π]-cycloaddition of 7,7′-(alkane-α,ω-diyl)bis-(cyclohepta-1,3,5-trienes) to 1,1-diphenylpropa-1,2-diene and cyclonona-1,2-diene in the presence of the catalytic system Ti(acac)₂Cl₂–Et₂AlCl. The structure of the isolated compounds has been reliably proved by modern spectral methods.     

Trifluoromethyl-containing pyrazolinyl (p-tolyl) sulfones: The synthesis and structure of promising antimicrobial agents

The regiospecific synthesis of a novel series of nine 4-phenyl- and 3-alkyl(aryl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-tosylpyrazoles (pyrazolinyl p-tolyl sulfones), as well as their antimicrobial activity against yeast, such as fungi, bacteria, and alga are reported. The 1-p-tosyl-2-pyrazolines were obtained from the cyclocondensation reaction of 3-phenyl- and 4-alkyl(aryl)-1,1,1-trifluoro-4-alkoxy-3-alken-2-ones, [where alkyl = H, Me and aryl are -C₆H₅, 4-CH₃C₆H₄, 4-OCH₃C₆H₄, 4-FC₆H₄, 4-ClC₆H₄, 4-BrC₆H₄,] with p-tosylhydrazine in a yield of 58-92% when toluene was employed as solvent. The best activity was obtained when the structure possessed a 4-fluorophenyl substituent linked at the carbon-3 of the pyrazoline ring. Subsequently, the dehydration reaction of 3-(4-fluorophenyl) substituted 2-pyrazoline with thionyl chloride/pyridine in benzene as solvent furnished the corresponding 1H-pyrazole in only a moderate yield (49%).     

The first application of 4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones in a three-component condensation protocol for the synthesis of 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-ones

The one-pot, simple and efficient three-component condensation protocol for the preparation of a series of twenty-five new 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-ones, where aryl = Ph, 4-tolyl, 4-ClPh, 4-NO₂Ph and 4-CHOPh, and acyl = Ac, Bz, 4-FBz, furan-2-oyl, thien-2-oyl and naphth-1-oyl, employing 1,3-cyclohexanedione, five aryl aldehydes and for the first time, six 4-alkyl(aryl/heteroaryl)-4-methoxy-1,1,1-trifluoroalk-3-en-2-ones, is described. Yields in 15-75% were obtained when the MCRs were performed in the presence of a catalytic amount of triethylamine (25 mol%) and in ethanol as solvent under reflux for 16 h. A representative X-ray diffraction data for 3-acetyl-4-phenyl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-one is also showed.     

Synthesis of electron-poor 4-halo-2-azabuta-1,3-dienes by Rh(II)-catalyzed diazo ester-azirine coupling. 2-Azabuta-1,3-diene-2,3-dihydroazete valence isomerism

The Rh₂(OAc)₄-catalyzed reaction of alkyl 2-acyl-2-diazoacetates and dimethyl diazomalonate with methyl 2-bromo- and 2-chloro-3-phenyl-2H-azirine-2-carboxylates gives rise to electron-poor 4-halo-substituted (3E)-2-azabuta-1,3-dienes. Their formation proceeds with complete stereoselectivity via ring-opening of the intermediate azirinium ylide. 2-Azabuta-1,3-dienes with electron-withdrawing substituents at the 1,1,4-positions are stable compounds at room temperature, but are in equilibrium with cyclic valence isomers, 2,3-dihydroazetes, at elevated temperatures.     

Ring-opening reactions of 3-substituted 1-azabicyclo[1.1.0]butane with dichlorocarbene

Reaction of 3-ethyl-1-azabicyclo[1.1.0]butane ( 1a ) with chloroform-potassium tert-butoxide afforded a ring-opened product, 1,1-dichloro-2-aza-4-ethylpenta-1,4-diene ( 4a ), which was characterized via conversion to the corresponding N-substituted 5-chloro-1,2,3,4-tetrazole, Sa . Reaction of 3-phenyl-1-azabicyclo-[1.1.0]butane ( 1b ) with “Seyferth's reagent” (PhHgCCl₂Br) afforded 1,1-dichloro-2-aza-4-phenylpenta-1,4-diene ( 4b ), which also was characterized via conversion to a tetrazole derivative, i.e., 5b . Finally, the reaction of 1b with dichlorocarbene generated under phase transfer conditions (chloroform-sodium hydroxide-TEBA) was studied. At short reaction times (0.5 hour), the major reaction product was 4b . However, at longer reaction times (20–30 hours), two secondary products, 8 and 9 , were formed which resulted via subsequent dichlorocyclopropanation of 4b .