Novel Mixed Complexes of Copper(II) and Ethylenediamine: Synthesis,Crystal Structure,and Catalytic Activity in the Cross-Coupling Reaction of 1-Phenyl-5<Emphasis Type="Italic">H</Emphasis>-tetrazole-5-thiol and Iodobenzene

Two earlier unknown complexes, [Cu(en)₂(Hptt)]Br (Hptt = 1-phenyl-1H-terazole-5-thiol, en = ethylenediamine) and trans-[Cu(en)2(H2O)Br]Br, have been synthesized and characterized using X-ray diffraction analysis. In [Cu(en)₂(Hptt)]Br complex, the copper cation is bonded with the N⁴ atom of tetrazole ring. Catalytic activity of the obtained complexes in cross-coupling reaction of 1-phenyl-5H-tetrazole-5-thiol with iodobenzene is comparable to that of CuBr₂ in the presence of 2 eq. of ethylenediamine.     

Diazepines I. A new synthesis of 6-phenyl-4H-imidazo[1,2-a] [1,4] benzodiazepines

6-Phenyl-4H-imidazo[1,2-a][1,4]benzodiazepines are obtained on reaction of 2-amino-7-chloro-5-phenyl-3H-1,4-benzodiazepine with α-bromoketones. In the cases of 3-bromo-2-butan-one and of 3-bromo-2-pentanone, 2-alkylimidazobenzodiazepine but not 1,2-dialkyl compound is the major product. A mechanism for the imidazole ring formation is presented.     

Preparation of 1,3-dienyl organotrifluoroborates and their Diels-Alder/cross-coupling reactions

2-BF₃-substituted 1,3-butadienes with potassium and tetrabutyl ammonium counterions have been prepared in gram quantities from chloroprene via a simple synthetic procedure. The potassium salt of this new main group element substituted diene has been characterized by ¹H, ¹³C, ¹¹B, and ¹⁹F NMR and the tetra n-butyl ammonium salt was also characterized by X-ray crystallography. Diels-Alder reactions of these dienes with dienophiles such as ethyl acrylate, methyl vinyl ketone, and N-phenylmaleimide are reported as well as subsequent Pd-catalyzed cross-coupling reactions of those Diels-Alder adducts. 4-Phenyl-2-BF₃-substituted 1,3-diene was prepared by magnesium-halogen exchange from the corresponding 2-bromo and iodo dienes. The 4-phenyl-2-bromo-1,3-butadiene was also characterized by X-ray crystallography. 4-Phenyl-2-BF₃-1,3-butadiene was used in Diels-Alder/cross-coupling reactions and the product of a Diels-Alder reaction with N-phenylmaleimide followed by cross-coupling with 4-bromo-benzonitrile was also characterized by X-ray crystallography.     

Electrophilic Substitution of Hydrogen in Betulin and Diacetylbetulin

Betulin and diacetylbetulin, which can be regarded as sterically hindered alkenes, reacted with N-chloro-, N-bromo-, and N-iodosuccinimides to give products of allylic and vinylic substitution in quantitative overall yield. The contribution of allylic substitution increases in the series Cl < Br < I. Quantum chemical simulation of the reactions of diacetylbetulin with N-halosuccinimides showed that, regardless of the electrophile power, all reactions involve open-chain carbocationic intermediates. The direction of deprotonation of the latter with formation of allylic or vinylic substitution products is determined by preferential orientation of the vacant orbital and C–Hlg bond.     

Derivatives of α,β-dehydroamino acids: V. Intramolecular cyclization of 2-{2-[(<Emphasis Type="Italic">Z</Emphasis>)-1-Benzamido-2-phenylvinyl]acetamidomethyl}benzimidazole

Reaction of 4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-one with 2-(1H-benzimidazol-2-yl)ethaneamine led to the formation of 2-{2-[(Z)-1-benzamido-2-phenylvinyl]acetamidomethyl}benzimidazole that in a reaction with hexamethyldisilazane in DMF gave 5-benzylidene-1-(1H-benzimidazol-2-yl)-2-phenyl-3,5-dihydro-4H-imidazol-4-one. In the presence of K₂CO₃ in dioxane the reaction with hexamethyldisilazane resulted in the product of intramolecular addition, N-(4-benzyl-3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]-benzimidazol-4-yl)benzamide     

Nature of solvation effects and mechanism of heterolysis of <Emphasis Type="Italic">tert</Emphasis>-alkyl halides

Specificities of heterolysis of tert-alkyl halides in protic and aprotic solvents were analyzed. Values of log k ₂₅ for heterolysis of tert-butyl chloride, tert-butyl bromide, tert-butyl iodiede, 1-chloro-1-methylcyclopentane, 1-chloro-1-methylcyclohexane, 1-bromo-1-methylcyclopentane, 1-bromo-1-methylcyclohexane, 2-chloro-2-phenylpropane, 1-iodoadamantane, and 2-bromo-2-methyladamantane in 19 to 44 solvents, determined mostly by the verdazyl technique were collected. Correlation analysis of solvation effects was performed in terms of multiparameter equations based on the linear free energy relationship principle, as well as in the logk-E _T coordinates. The nature of solvation effects and mechanism of heterolysis of a covalent C-Hlg bond were discussed.     

Complexes of copper(II) and cobalt(II) halides with 4-(3,5-dimethyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-1-yl)-6-methyl-2-phenylpyrimidine: Synthesis,structures, and properties

Copper(II) and cobalt(II) complexes with 4-(3,5-dimethyl-1H-pyrazol-1-yl)-6-methyl-2-phenylpyrimidine (L) of the general formula MLX₂ (M = Cu(II), X = Cl and Br; M = Co(II), X = Cl, Br, and I) were obtained. According to X-ray diffraction data, CuLBr₂ and CoLX₂ (X = Cl, Br, and I) are mononuclear molecular complexes. The ligand L is coordinated to the metal atom in a chelating bidentate fashion through the N atoms of the pyrimidine and pyrazole rings. The coordination polyhedron of the metal atom is extended to a distorted tetrahedron by two halide ions. In solution, CuLBr₂ undergoes slow transformation into CuL_(1?x)L′ _x Br₂ and the binuclear (X-ray diffraction data) Cu(I) complex [CuL_(1?x)L′ _x Br]₂ (L′ is 4-(4-bromo-3,5-dimethyl-1H-pyrazol-1-yl)-6-methyl-2-phenylpyrimidine). The complexes MLX₂ show weak antiferromagnetic interactions between the M²⁺ ions.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-and <Emphasis Type="Italic">C</Emphasis>-trimethylsilyl-substituded anililes

N-Metallation of bromoanilines with ethylmagnesium bromide followed by a reaction with trimethylchlorosilane provided N-mono and N-bis(trimethylsilyl)bromoanilines depending on the structure of substrate. The metallation of bissilylated bromoanilines with butyllithium permitted the introduction of a trimethylsilyl substituent in the aromatic ring. Previously unknown 2-bromo-N,N-bis(trimethylsilyl)aniline, 2,6-dibromo-N-trimethylsilylaniline, 2,6-dibromo-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilylaniline, 2-bromo-6-trimethylsilyl-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilyl-N-trimethylsilylaniline, 2,4,6-tribromo-N-trimethylsilylaniline, and 2,4,6-tribromo-N,N-bis(trimethylsilyl)aniline were prepared. The structures of the compounds obtained were established by the chromato-mass spectrometry and ¹H, ¹³C, and ²⁹Si NMR spectroscopy.     

Conjugate halo- and mercuroazidation of 1-phenyltricyclo-[4.1.0.0<Superscript>2.7</Superscript>]heptane. Synthesis of a conformationally rigid α-amino acid with a bicyclo[3.1.1]heptane skeleton

1-Phenyltricyclo[4.1.0.0^2.7]heptane reacted with N-bromo-, N-chloro-, and N-iodosuccinimides and with mercury(II) acetate in the presence of sodium azide as external nucleophile to give conjugate addition products to the central C¹–C⁷ bicyclobutane bond with a norpinane structure, where the azido group and the phenyl were attached to the same carbon atom (C⁶). The bromo- and chloroazidation showed anti-stereo-selectivity, and the iodoazidation, moderate syn-stereoselectivity; the mercuroazidation afforded exclusively the corresponding syn-addition product. Hydro-, bromo- and chlorodemercuration of the mercury adduct with sodium tetrahydridoborate and elemental bromine and chlorine, respectively, did not involve the azido group, and the original configuration was retained. The reduction of the hydrodemercuration product with LiAlH₄ gave 6-exo-phenylbicyclo[3.1.1]heptan-6-amine which was transformed in three steps into conformationally rigid 6-endo-(acetamido)bicyclo[3.1.1]heptane-6-carboxylic acid.     

Reaction of Thiocarboxylic Acids with <Emphasis Type="Italic">N</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butyl-2-halo-2-methylpropanimines

Reaction of N-tert-butyl-2-chloro-2-methylpropanimine with thiocarboxylic acids has proceeded by two routes, one involving nucleophilic substitution of the chlorine atom in the primary iminium salt by acylthio group, and another via reduction of its cation at the C–Cl bond. Thiocarboxylic acids have reacted with 2-bromoaldimines only via reduction of primary salt cation at the C–Br bond. Acylthio-substituted iminium salts, aldehydes, and their acetals have been prepared.     

Sc(OTf)<Subscript>3</Subscript> catalyzed synthesis of novel 6-phenyl-6<Emphasis Type="Italic">H</Emphasis>-chromeno[4,3-b]quinolines and evaluation of their cytotoxicity

Novel 6-phenyl-6H-chromeno[4,3-b]quinoline derivatives have been prepared by reaction of 4-chloro-2-phenyl-2H-chromene-3-carbaldehyde with various aromatic amines using 5 mol % of Sc(OTf)3 in acetonitile. This is the first example of one-pot synthesis of 6-phenyl-6H-chromeno[4,3-b]quinoline from 4-chloro-2-phenyl-2H-chromene-3-carbaldehyde at ambient temperature. Preliminary evaluation of cytotoxic activity of these chromeno[4,3-b]quinoline derivatives has been carried out. Some products exhibited anti cancer activity against two carcinoma cell lines A549 and B-16.     

Stereoselectivity of halomethoxylation of 1-phenyltricyclo-[4.1.0.0<Superscript>2,7</Superscript>]heptane and methyl 7-phenyltricyclo[4.1.0.0<Superscript>2,7</Superscript>]-heptane-1-carboxylate

The stereoselectivity of halomethoxylation of 1-phenyltricyclo[4.1.0.0^2,7]heptane and methyl 7-phenyltricyclo[4.1.0.0^2,7]heptane-1-carboxylate at the central bicyclobutane C¹-C⁷ bond by the action of N-chloro-, N-bromo-, and N-iodosuccinimides in methanol depends on the halogen nature. Conjugate chlorination and bromination are characterized by pronounced anti-stereoselectivity; the contribution of syn-addition slightly increases in going from the monosubstituted tricycloheptane substrate to disubstituted. Iodomethoxylation of the latter is clearly syn-stereoselective.     

1-Bromo-3,3,3-trifluoro-1-nitropropene: Synthesis and reaction with phenyl azide

An improved procedure was developed for the synthesis of 3,3,3-trifluoro-1-nitropropene, and a new representative of gem-bromonitroalkenes, 1-bromo-3,3,3-trifluoro-1-nitropropene, was synthesized therefrom. Its reaction with phenyl azide gave a mixture of two regioisomeric 1,2,3-triazoles, from which pure 5-nitro-1-phenyl-4-(trifluoromethyl)-1H-1,2,3-triazole was isolated.     

Synthese und reaktionen von 1-germcyclohexa-2,4-dienen und 1-germacyclohexa-2,4-dien-eisentricarbonylen

1,1-Diakyl(aryl)4-alkyl(aryl)-4-methoxy-1-germacyclohexa-2,5-dienes undergo ether cleavage with sodium in n-pentane or liquid ammonia. Hydrolysis of the resulting sodium salts yields the 1,1-dialkyl(aryl)-4-alkyl(aryl)-1-germacyclohexa-2,4-dienes. Reduction of 1-chloro-4-methoxy-1-germacyclohexa-2,5-dienes with LiAlH₄ can be directed to give the 1H-1-germacyclohexa-2,4-dienes with ether cleavage.The 1H-1-germacyclohexadienes are chlorinated by PCl₅ and brominated by N-bromosuccinimide to the 1-chloro- or 1-bromo-1-germacyclohexa-2,4-dienes, respectively. 1,1-Diethyl-4-phenyl-4-methoxy-1-germacyclohexa-2,5-diene reacts with PCl₃ with ether cleavage and formation of the 6-chloro-1-germacyclohexa-2,4-diene. Ether cleavage is also possible with BCl₃, the 1-phenyl-1-chloro-4R-4-methoxy-1-germacyclohexa-2,5-dienes are transformed into the 1-phenyl-1,6-dichloro-4R-1-germacyclohexa-2,4-dienes.The Fe(CO)₃ complexes of 1,1-dialkyl(aryl)-1-germacyclohexa-2,4-dienes were synthesized.     

Synthesis and bromination/dehydrobromination of <Emphasis Type="Italic">N,N</Emphasis>-diallyltrifluoromethanesulfonamide

The reaction of triflluoromethanesulfonamide with allyl bromide in dimethyl sulfoxide gave N,N-diallyltrifluoromethanesulfonamide which was subjected to bromination with 1 and 2 equiv of bromine. The product of bromine addition to both allyl groups, CF₃SO₂N(CH₂CHBrCH₂Br)₂, was found to exist as a mixture of two diastereoisomers at a ratio of 9: 11. Its dehydrobromination by the action of sodium methoxide was chemoselective with successive elimination of one, two, and three hydrogen bromide molecules to afford N-(2-bromoprop-2-en-1-yl)-N-(2,3-dibromopropyl)trifluoromethanesulfonamide, N,N-bis(2-bromoprop-2-en-1-yl)trifluoromethanesulfonamide, and N-(2-bromoprop-2-en-1-yl)-N-(propadienyl)trifluoromethanesulfonamide, respectively.     

Reactions of polyhalomethanes with olefins catalyzed by copper complexes with aromatic amino alcohols

Copper complexes with amino alcohols structurally similar to ephedrin (1-phenyl-3-(N-methylamino)propan-1-ol and 1-phenyl-2-(N-methylamino)ethanol) are catalytically very active in the free-radical addition of CCl₄ and CBr₄ to linear alk-1-enes. These amino alcohols themselves are initiators of radical addition reactions, and, in the reaction with CBr₄, they are more active than the metal complexes. In the presence of the amino alcohols, as distinct from classical radical initiators, the reaction is highly selective and affords an addition product. An analysis of kinetic equations and the data obtained for the reaction involving CHCl₃ suggest that the amino alcohols and the corresponding metal complexes are involved in different ways in the addition of CCl₄ and CBr₄ to linear alk-1-enes.     

Reaction of 2-methylquinoline with 3-phenylprop-2-ynenitrile in the KOH—H<Subscript>2</Subscript>O system

The reaction of 2-methylquinoline with 3-phenylprop-2-ynenitrile in the presence of water (0—25 °C, 20 mol.% KOH, 5 equiv. H₂O) is accompanied by the loss of aromaticity of the quinoline nucleus and results in double functionalization of the molecule at the nitrogen atom and the methyl group. Two 2-cyano-1-phenylethenyl groups were introduced into the molecule to form (2E,4E)-4-{1-[(Z)-2-cyano-1-phenylethenyl]quinolin-2(1H)-ylidene}-3-phenylbut-2-enenitrile in 59—67% yield. This reaction is stereoselective: the N-2-cyano-1-phenylethenyl-substituent has the Z-configuration, while the 1,3-diene moiety at the methyl group has the E,E-configuration. (2E)-3-Phenyl-4-(quinolin-2-yl)but-2-enenitrile that formed as a by-product (0—24% yields) is formally the addition product of the methyl group of the quinoline substrate at the acetylenic bond.     

Reaction of transsilylation of <Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="Italic">N</Emphasis>-trimethylsilylacetamide with silanes ClCH<Subscript>2</Subscript>SiR<Superscript>1</Superscript>R<Superscript>2</Superscript>Cl

The reaction of N-methyl-N-trimethylsilylacetamide with silanes ClCH₂SiR¹R²Cl (R¹, R² = H, Me; H, Ph; Ph₂) leads to the formation of (O→Si) chelate compounds with pentacoordinate silicon: N-[chloro(methyl)-silyl]methyl-, N-[chloro(phenyl)silyl]methyl-, and N-[chloro(diphenyl)silyl]methyl-N-methylacetamides. From the data of multinuclear NMR spectroscopy, the intermediates of the reaction of N-methyl-N-trimethylsilylacetamide with ClCH₂SiPhHCl and ClCH₂SiPh²Cl are stable in CDCl₃ solution at room temperature during several days and slowly rearrange to the final (O–Si) chelate compounds.     

Polyfunctional imidazoles: XIII.<Superscript>1</Superscript> Addition and cyclization reactions of 1-aryl-4-chloro-5-(2-nitroethenyl)-1<Emphasis Type="Italic">H</Emphasis>-imidazoles with sulfur and nitrogen nucleophiles

1-Aryl-4-chloro-5-(2-nitroethenyl)-1H-imidazoles reacted with thiols and aromatic amines via Michael addition to give 5-[(1-arylsulfanyl)-2-nitroethyl)]-4-chloro-1H-imidazoles and N-[1-(1-aryl-4-chloro-1H-imidazol-5-yl)-2-nitroethyl]anilines, respectively. [2 + 3]-Cycloaddition of the title compounds to sodium azide afforded 4-(4-chloro-1H-imidazol-5-yl)-1H-1,2,3-triazoles.     

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 .