Electrochemically induced transformation of 4(6)-dihalomethyl-4(6)-methylcyclohexa-2,5(2,4)-dien-1-ones into 4(2)-methyltropones

Electrochemical investigation of 4(6)-dihalomethyl-4(6)-methylcyclohexa-2,5(2,4)-dien-1-ones using cyclic voltammetry (CVA) and rotating disc electrode (RDE) methods has been performed. The reductive dehalogenation of cyclohexa-2,5(2,4)-dien-1-ones having a dihalomethyl substituent at the tertiary carbon atom was shown to proceed as a two-electron reductive elimination of the geminal halogen atoms with the intermediate formation of carbene and subsequent rearrangement of cyclohexadienone with the ring expansion to the corresponding 4- or 2-methylcyclohepta-2,4,6-trien-1-one.     

1,3-Dioxolan-4-ones and 1,3-oxathiolan-5-ones. Configuration of cis and trans isomers

The attempted acid-catalyzed azeotropic removal of water from a mixture containing lactamide and chloral in refluxing toluene lead to the elimination of ammonia; both cis- and trans-5-methyi-2-(trichloromethyl)-1,3-dioxolan-4-one were isolated. A number of 1,3-dioxolan-4-ones and 1,3-oxathiolan-5-ones were obtained by cyclodehydration of aldehydes with α-hydroxy- and α-mercapto-carboxylic acids in the presence of boron trifluoride etherate. Geometric isomers were separated, and their configurations were determined by nuclear magnetic resonance.     

Electrochemical study of the sequence of reductive dehalogenation of 2-bromo-5-dibromomethyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one and its analogs

The electrochemical behavior of a series of halogen-containing cyclohexa-2,5-dien-1-ones at the glassy-carbon electrode in DMF was studied. The reductive dehalogenation of 2-bromo-5-dibromomethyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one first results in the elimination of the carbonylallylic bromine atoms, then the carbonylic bromine atom is elimi-nated, and finally, the neopentylic chlorine atoms are eliminated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1558–1564, September, 2006.     

Chloromethyl-, dichloromethyl-, and trichloromethyl-1,2,4-triazines and their 4-oxides: method for the synthesis and tele-substitution reactions with C-nucleophiles

A simple procedure was developed for the synthesis of 1,2,4-triazines and their 4-oxides containing the ClCH₂, Cl₂CH, or CCl₃ group at position 3 by cyclization of 2-aryl-2-hydrazono-1-oximinoethanes with the corresponding chloroacetonitriles. The reaction pathway depends on the number of halogen atoms in the acetonitrile used. The reactions with trichloroacetonitrile, monochloroacetonitrile, and dichloroacetonitrile afford 3-trichloromethyl-1,2,4-triazines, 3-chloromethyl-1,2,4-triazine 4-oxides, and a mixture of the corresponding dichloromethyltriazines and their 4-oxides, respectively. The reactions of 3-trichloromethyl-1,2,4-triazines with indoles and phenols are accompanied by tele-substitution with elimination of halogen from the trichloromethyl group to give 5-indolyl- (or 5-hydroxyphenyl)-3-dichloromethyl-1,2,4-triazines.     

A facile and novel synthesis of 5-phenylimidazo[4,5-c][1,8]naphthyridin-4(5H)-ones

A convenient and regioselective synthesis of a new heterocycle, 5-phenyl-1H or 3H-imidazo[4,5-c][1,8]-naphthyridin-4(5H)-one 1-a or 1-b , is described. Methyl 2-anilinonicotinate 15 was transformed into the valuable intermediate, N-phenyl-3-azaisatoic anhydride 4 using trichloromethyl chloroformate (TCF). Treatment of 4 with the anion of ethyl nitroacetate gave 4-hydroxy-3-nitro-1-phenyl-1,8-naphthyridin-4(5H)-one 3 . Compound 3 was chlorinated, aminated, reduced, and cyclized to afford 5-phenylimidazo[4,5-c][1,8]naphthyridin-4(5H)-one 1 . Regioselective substitution at the 1 or 3-position in the imidazole moiety of 1 was achieved by minor changes of the above scheme.     

Tetradentate nitrogen-containing ligands bis-5-(2-pyridylmethylidene)-3,5-dihydro-4<Emphasis Type="Italic">H</Emphasis>-imidazol-4-ones and their coordination compounds with Cu<Superscript>I</Superscript> and Cu<Superscript>II</Superscript>

Tetradentate N₄-type organic ligands containing two 5-(2-pyridylmethylidene)-2-thio-3,5-dihydro-4H-imidazol-4-one fragments linked by two-, four-, or six-carbon polymethylene bridges between the sulfur atoms were synthesized. Mono- and dinuclear complexes of these ligands with copper(II) chloride, as well as with copper(I) and copper(II) perchlorates, were prepared. The structure of the coordination compound (5Z,5′Z)-2,2′-(butane-1,2-diyl-disulfanyldiyl)bis-5-(2-pyridylmethylidene)-3-phenyl-3,5-dihydro-4H-imidazol-4-one with copper(I) perchlorate was established by X-ray diffraction. The copper atom in this complex is in a distorted tetrahedral coordination formed by four nitrogen atoms of two imidazole and two pyridine rings. The perchlorate anion is located in the outer sphere of the complex and is not involved in the coordination with the copper ion. The electrochemical study of the ligands and the complexes was carried out by cyclic voltammetry and rotating disk electrode voltammetry. The initial reduction of the complexes under study occurs at the metal atom. The length of the polymethylene bridge in the ligand has only a slight effect on the redox properties of the ligands and the complexes.     

2-甲基-1,5-苯并硫氮杂的基态和激发态反应的研究 I: 2-甲基-1,5-苯并硫氮杂-4(5H)-酮的卤化和亲核取代反应

2-甲基-1,5-苯并硫氮杂-4(5H)-酮(1a)与不同的氯化试剂-五氯化磷、三氯氧磷和氯化砜在不同的条件下氯化,可分别生成:2-甲基-4-氯-1,5-苯并硫氮杂(2a)、2-氯-4-甲基-1,5-苯并硫氮杂(3a)、2-二氯甲基苯并噻唑(5)、2-三氯甲基苯并噻唑(6)和2-甲基-1,5-苯并硫氮杂-4(5H)-酮盐酸盐(4).2-甲基-4-氯-1,5-苯并硫氮杂与醇钠反应生成相应的2-甲基-4-烷氧基-1,5-苯并硫氮杂外,还可以分离到它的2,4-异构体,2-烷氧基-4-甲基-1,5-苯并硫氮杂.产物的结构均经元素分析、红外光谱、^1H和^1^3C核磁共振谱和质谱鉴定.     

Preparation of 5-chloropyrazoles via tandem Meyer–Schuster/von Auwers rearrangements

A new, practical preparation of β,β-dichloroenones in three to four steps allows for a straightforward synthesis of 5-chloropyrazoles. Addition of various propargyl anions to commercially available 4-methyl-4-(trichloromethyl)cyclohexa-2,5-dien-1-one gives high yields of the corresponding propargyl alcohols. These are then transformed, in a single step, via two consecutive rearrangements, a Meyer–Schuster and a (sometimes spontaneous) von Auwers rearomatizing rearrangement, to deliver α,α-aryl-trichloromethylketones. After elimination of HCl, cyclization of the β,β-dichloroenones with various hydrazines delivers 5-chloropyrazoles. The four to five step sequence to 5-chloropyrazoles is very atom economical, expelling only water and two molecules of HCl from all the building blocks.     

Synthesis of 1,2-benzisothiazolin-3-ones by ring transformation of 1,3-benzoxathiin-4-one 1-oxides

1,2-Benzisothiazolin-3-ones were synthesized from 1,3-benzoxathiin-4-one 1-oxides by means of a nonhazardous and inexpensive method. The 1,3-benzoxathiin-4-one 1-oxides were prepared by oxidation of 1,3-benzoxathiin-4-ones with hydrogen peroxide in the presence of a catalyst. Attack of amines on the carbonyl groups of the 1,3-benzoxathiin-4-one 1-oxides and subsequent elimination of carbonyl compounds likely produced sulfenic acids, which then underwent ring closure to afford the 1,2-benzisothiazolin-3-ones.     

Synthesis and Bioactivity of Novel Aminomethyl-2-（1, 2,4-triazol）-4, 4-dimethyl-3-pentanone （ol）

3, 3-Dimethyl-1-(1,2,4-triazol)-2-butanone was treated with aqueous formaldehyde to give an additional product, and subsequent elimination by acetic anhydride yielded 4,4-dimethyl-2-(1,2,4-triazol)-1-penten-3-one. Further addition with substituted amines provideda series of (1,2,4-triazol)-4,4-dimethyl-3-pentanone, which were then reduced by KBH4 to obtaina series of (1,2,4-triazol)-4,4-dimethyl-3-pentanol. Their structures were confirmed by ^1HNMR and elemental analysis. The results of bioassay showed that the title products possess good fungicidal activities.     

Heteroligand complexes of lanthanides with 4-formyl-3-methyl-1-phenylpyrazol-5-one and 1,10-phenanthroline

Complexes of the general formula LnL₃ · Phen (Ln = Nd, Sm, Eu, Gd, Tb, Dy, and Yb; HL = 4-formyl-3-methyl-1-phenylpyrazol-5-one, Phen = 1,10-phenanthroline) were obtained and examined by IR spectroscopy and thermogravimetry. The structure of the complex TbL₃ · Phen was studied by X-ray diffraction. The coordination polyhedron of terbium is a distorted square antiprism made up of six O atoms of three 4-formylpyrazol-5-one anions and two N atoms of the 1,10-phenanthroline molecule. Polycrystalline samples of the complexes studied show emission in the spectral ranges characteristic of Ln(III).     

An efficient synthesis of designed 4-thiazolidinone fused pyrimidine derivatives as potent antimicrobial agents

A novel series of hybrid 2-substituted ((pyrimidin-2-yl)hydrazinyl)thiazolidin-4-one derivatives were synthesized by means of aromatic nucleophilic displacement of chlorine atoms of 2,4,6-trichloro pyrimidine. Synthesis of some novel 2-(2-(6-morpholino-4-substituted(phenyl amino)pyrimidin-2-yl)hydrazinyl)thiazol-4(5H)-one derivatives have been carried out by the displacement of chlorine atoms on the basis of functionality concept on varying conditions. The synthesized hydrazinyl thiazolidin-4-one pyrimidine derivatives were evaluated for their expected antimicrobialactivity; where, the majority of these compounds showed potent antibacterial and antifungal activities against the tested strains of bacteria and fungi. Afforded title analogs were subsequently characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, Mass spectroscopy. SAR and HOMO-LUMO studies were also carried out for confirming the structure biological activity. Thus, these studies suggested that hydrazinyl pyrimidine derivatives bearing thiazolidinone moiety are interesting scaffolds for the development of novel antimicrobial agents.     

1，3，4，6－四硫代戊搭烯－2，5－二酮制备含硫取代基的四硫富瓦烯的研究

以１，３，４，６－四硫代戊搭烯－２，５－二酮为原料，经偶联、醇解、烃化或醇解、烃化、偶联等步骤，制得四甲硫基四硫富瓦烯、四乙硫基四硫富瓦烃、二喹喔啉硫醚、４－甲硫基－５－甲氧甲酰硫基－１，３－二硫环戊烯－２－酮、四甲硫基乙烯和４，４＇－二甲硫基－５，５＇－二甲氧甲酰硫基四硫富瓦烯及它的异构体混合物．提出了１，３，４，６－四硫代戊搭烯－２，５－二酮醇解机理．讨论了未得到某些预期产物的原因．报道了３种四硫富瓦烯衍生物的循环伏安图及电化学性质．     

Boron chelates with 5,5,5-trifluoro- and 5,5,5-trichloro-4-aminopent-3-en-2-ones

Boron chelates were obtained by the reaction of butoxy(butylthio)diphenylborane with 5,5,5-trifluoro(trichloro)-4-aminopent-3-en-2-one, and their reactions with primary amines were investigated. -Diiminate complexes of boron with trifluoro- and trichloromethyl groups were synthesized.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2657–2661, November, 1992.     

Pyrolysis of 5-chloropentan-2-one and 4-chloro-1-phenylbutan-1-one. Participation of the carbonyl group

The rates of elimination of 5-chloropentan-2-one and 4-chloro-1-phenylbutan-1-one in the gas phase have been determined in a static system, seasoned with allyl bromide, and in the presence of the chain inhibitor propene. The reactions are unimolecular and follow a first-order rate law. The working temperature and pressure ranges were 339.4–401.1°C and 46–117 torr, respectively. The rate coefficients for the homogeneous reactions are given by the following Arrhenius equations: for 5-chloropentan-2-one, log k₁(s^?1) = (13.12 ± 0.88) - (207.8 ± 11.0)kJ/mol/2.303RT; and for 4-chloro-1-phenylbutan-1-one, log k₁(s^?1) = (12.28 ± 1.09) - (185.2 ± 12.0)kJ/mol/2.303RT. The carbonyl group at the γ position of the C? Cl bond of haloketones apparently participates in the rate of pyrolysis. The five-membered conformation appears to be a favorable structure for anchimeric assistance of the C?O group in the gas-phase elimination of chloroketones.     

2, 3, 4, 5, 6-五苯基苯甲醛的新合成途径

从四苯基环戊二烯酮与乙二醇缩肉桂醛通过干法在260-270℃直接加成并脱CO,接着经氧化、水解制备了2,3,4,5,6-五苯基苯甲醛,对目标产物的结构进行了^1HNMR,IR,UV-Vis和元素分析表征。在对反应中间产物进行分离、鉴定的基础上提出了该反应的可能途径。     

Mechanism of the reaction of 2-methoxybenzo[d][1,3,2]dioxaphosphinin-4-one with chloral by quantum-chemical calculations

Quantum-chemical calculations of various stereoisomers, intermediates, and transition states of the reaction of 2-methoxybenzo[d][1,3,2]dioxaphosphinin-4-one with chloral, leading to formation of 2-methoxy-3-(trichloromethyl)benzo[e[1,4,2 ⁵]dioxaphosphepin-2,5-dione, were carried out by the density functional theory (DFT) method with the PBE functional and Triple z basis, using the Priroda program. The first step of the reaction is [1+2] cycloaddition of phosphorus to the chloral C=O bond to form an intermediate with a five-coordinate phosphorus atom via a transition state in which the positive and negative charges are strongly localized on phosphorus and chloral oxygen, respectively. Calculations of the internal reaction coordinate from all transition states were carried out.     

Nuclear Quadrupole Resonance and Stereochemistry III. Trichloromethyl derivatives

³⁵Cl nuclear quadrupole resonance frequencies are reported of the chlorine atoms in the trichloromethyl group of benzotrichlorides and trichloromethyl derivatives of heterocyclic molecules. They are compared with previously reported results for the same group attached to other planar conjugated radicals. In such compounds the three chlorine atoms cannot be equivalent and all the results are discussed from the point of view of possible orientation-dependant hyperconjugation between the C? Cl bonds and the conjugated moiety, particularly with reference to the marked effects observed in trichloromethyl ethers reported in part I of this series. In the benzo-trichloride and indeed most of the compounds discussed such effects are small.     

The reaction of 2-acetoacetamidopyridines with phosgene. A route to novel 3-Acetyl-2-chloro-4H-pyrido[ 1,2-a] pyrimidin-4-ones

2-(Acetoacetamido)pyridine, 1 , and its 5-methyl derivative, 2 , with phosgene, gave 3-acetyl-2-chloro-4H-pyrido[1,2-a]pyrimidin- 4 -one, 5 , and 3-acetyl-2-chloro-7-methyl-4H-pyrido[1,2-a]-pyrimidin-4-one, 6 , respectively. The structures of these compounds followed from their elemental analyses, and interpretations of their uv, ir, pmr, and X-ray spectra. An alternative route to 5 and 6 , which sought first to react 1 and 2 with methyl - and benzyl chloroformates, was unsuccessful, and led, instead, to elimination of the acetoacetyl group with concomitant formation of the carbamate derivatives, 10 and 11 .     

An electrochemical interpretation of the mechanism of the chemical decarboxylation of 6-carboxyperhydropyrimidin-4-ones

The present work analyzes the anodic oxidation of the tetrabutylammonium salt of 1-benzoyl-2(S)-tert-butyl-6(S)-carboxyperhydropyrimidin-4-one, which is a useful starting material in the synthesis of enantiopure α-substituted β-amino acids. It was demonstrated that in CH₂Cl₂ solvent, the anodic oxidation reaction results in fast and complete decarboxylation, followed by proton elimination thereby leading to the same product of chemical (diacetoxyiodobenzene) oxidative decarboxylation. The electrochemical mechanism involves two electron transfer steps, but appears as a monoelectronic process owing to the release of one proton from the key acyliminium carbocation intermediate. The relative stability of this intermediate and the suppression of any solvolysis reaction in CH₂Cl₂ allow for the detection of the acyliminium intermediate by means of cyclic voltammetry experiments. By contrast, in the presence of a nucleophilic solvent such as acetonitrile, the acyliminium intermediate is trapped in a typical Ritter reaction.