开环茂金属成环及氢分子消除反应机理的理论研究

采用密度泛函方法(DFT)在M06-2X/def2-TZVPP//B3LYP/def2-TZVPP+ZPE水平下, 对以开环的(η⁵-C₅H₇)₂Ru为前驱体生成闭环(η⁵-C₅H₅)₂Ru的各种可能的反应路径进行了详细的研究. 最终确定其反应机理为: (η⁵-C₅H₇)₂Ru的一个η⁵-C₅H₇发生端碳成键的成环反应形成(η³-C₅H₇)Ru(η⁵-C₅H₇), 经过两步氢原子迁移到Ru原子上, 之后脱掉一个氢气分子形成(η⁵-C₅H₅)Ru(η⁵-C₅H₇), 而后另一个η⁵-C₅H₇再重复成环并进行两步氢迁移以及氢气分子消除而得到最终的产物(η⁵-C₅H₅)₂Ru.     

Synthesis of New 2,4‐Diaryl‐6‐methyl‐5‐nitropyrimidines as Antibacterial and Antioxidant Agents

A new series of 2,4‐diaryl‐6‐methyl‐5‐nitropyrimidines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i ) were synthesized in good yields by Suzuki–Miyaura coupling of 2,4‐dichloro‐6‐methyl‐5‐nitropyrimidine ( 3 ) with various aryl boronic esters ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i ) in the presence of 1,1′‐ bis(diphenylphosphino)ferrocene dichloropalladium(II) (Pd(dppf)₂Cl₂). Further, antibacterial and antioxidant properties were screened for the title compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i . Most of the compounds possessed significant activity against Gram‐positive bacteria Staphylococcus aureus and Bacillus subtilis and Gram‐negative bacteria Escherichia coli and Klebsiella pneumoniae. The antioxidant activity of the title compounds showed significant antioxidant activity when compared with vitamin C.     

Concise synthesis of 5-methyl-, 5-formyl,and 5-carboxy analogues of 2′-deoxycytidine-5′-triphosphate

We describe a concise and efficient synthesis of 5-methyl-, 5-formyl-, and 5-carboxy-analogues of 2′-deoxycytidine-5′-triphosphate which are well known for their various biological applications. A protection-free one-pot synthesis was used to convert 5-methyl-2′-deoxycytidine into 5-methyl-2′-deoxycytidine-5′-triphosphate in high yield. 5-Formyl-2′-deoxycytidine-5′-triphosphate was obtained upon photosensitized oxidation (UV-A irradiation, λ ∼365 nm) of an aerated aqueous solution of 5-methyl-2′-deoxycytidine-5′-triphosphate with the use of menadione as the photosensitizer. 5-Formyl-2′-deoxycytidine-5′-triphosphate was converted into 5-carboxy-2′-deoxycytidine-5′-triphosphate by using biphasic TEMPO/BAIB oxidation method in high yield.     

Synthesis and Herbicidal Activity of Muti‐Substituted Pyrido[4,3‐d]pyrimidin‐4‐ones

A series of novel muti‐substituted pyrido[4,3‐d]pyrimidin‐4‐one derivatives 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l were designed and synthesized by the muti‐step reaction. N,S‐acetal 1 reacted with acetyl acetamide in the presence of zinc nitrate to obtain muti‐substituted pyridine 2 , which reacted with triethyl orthoformate to give 8‐cyano‐5‐methyl‐7‐methylthio‐pyrido[4,3‐d]pyrimidin‐4‐one 3 ; the target compounds 5 were obtained in good yields by the oxidation of 3 with H₂O₂ in a catalytic amount of sodium tungstate then by the substitution with various substituted phenols. Their structures were confirmed by IR, ¹H NMR, EI‐MS, and elemental analyses. The preliminary bioassay indicated that some of them displayed moderate herbicidal activity against dicotyledonous weed Brassica campestris L. at the concentration of 100 mg/L. For example, compounds 5a , 5f , and 5g possessed 76.0%, 62.7%, and 60.2% inhibition against B. campestris at the concentration of 100 mg/L. Moreover, 5a exhibited 58.2% inhibition against B. campestris at the concentration of 10 mg/L.     

Les Phases Na5NbO5 et Na5TaO5 Structure Cristalline de Na5NbO5

Na₅Nb0₅ and Na₅Ta0₅ Phases. Crystal Structure of Na₅NbO₅ New ternary oxides of formulas Na₅NbO₅ and Na₅TaO₅ have been prepared. They crystallize in the monoclinic system (space group C2/c). The crystal structure of Na₅NbO₅ has been determined. It derives from a NaCl-type structure by ordering of the cations and of the oxygen vacancies in the anionic sublattice, the corresponding formula being Na_5/6Nb_1/6O_5/6□_1/6. Sodium and niobium have a distorted square-pyramidal surrounding.     

Synthesis and Insecticidal Activity of Tetrazole‐Linked Triazole Derivatives

A new series of 4‐(4‐substitutedbenzylideneamino)‐5‐((1‐methyl‐1H‐tetrazol‐5‐ylthio)methyl)‐4H‐1,2,4‐triazole‐3‐thiol derivatives ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k ) are prepared using 4‐amino‐5‐((1‐methyl‐1H‐tetrazol‐5‐ylthio)methyl‐4H‐1,2,4‐triazole‐3‐thiol ( 4 ), as an intermediate compound. The structures of all the newly synthesized products are established supported by their spectral ¹H NMR, ¹³C NMR, FTIR, electrospray ionization mass spectrometry (mass), and analytical data. All the compounds are screened for their insecticidal activity against Plodia interpunctella, and six compounds exhibited significant activity.     

Photochemical reactions of 6-alkylamino- and 6-alkylanilino-5H-benzo[a]phenothiazin-5-ones

Photochemical reactions of 6-alkylamino- and 6-alkylanilino-5H-benzo[a]phenothiazin-5-ones have been investigated. 6-Ethylamino- and 6-isopropylamino-5H-benzo[a]phenothiazin-5-ones and 6-methylanilino- and 6-ethylanilino-5H-benzo[a]phenothiazin-5-ones gave 6-amino-5H-benzo[a]phenothiazin-5-one and 6-anilino-5H-benzo[a]phenothiazin-5-one, respectively, on irradiation.     

Photochemical reactions of allyl and crotyl halides with cyclopentadienyl-chromium, -molybdenum and -tungsten complexes

[MoCl(CO)₃(η⁵-C₅H₅)] on photolysis with allyl or crotyl halides C₅H₄RX gives Mo^IV complexes [MoX₂(CO)(η³-C₃H₄R)(η⁵-C₅H₅)] (R = H, X = Cl, Br, I; R = Me, X = Cl, Br). [WCl(CO)₃(η⁵-C₅H₅)] under similar conditions gives trihalides [WX₃(CO)₂(η⁵-C₅H₅)] (X = Cl, Br) on reaction with C₃H₅Cl and C₃H₅Br while [WCl(CO)₃(η⁵-C₅H₄SiMe₃)] and [CrI(CO)₃(η⁵-C₅H₅)] react with allyl chloride to give [WCl₃(CO)₂(η⁵-C₅H₄SiMe₃)] and [CrCl₂(η⁵-C₅H₅)] respectively.     

Synthesis of (5R)- and (5S)-5-Methyl-5, 6-dihydrouridine Derivatives

The hydrogenation of 2′, 3′-O-isopropylidene-5-methyluridine (1) in water over 5% Rh/Al₂O₃ gave (5 R)- and (5 S)-5-methyl-5, 6-dihydrouridine (2) , separated as 5′-O-(p-tolylsulfonyl)- (3) and 5′-O-benzoyl- (5) derivatives by preparative TLC. on silica gel and ether/hexane developments. The diastereoisomeric differentiation at the C(5) chiral centre depends upon the reaction media and the nature of the protecting group attached to the ribosyl moiety. The synthesis of iodo derivatives (5 R)- and (5 S)- 4 is also described. The diastereoisomers 4 were converted into (5 R)- and (5 S)-2′, 3′,-O-isopropylidene-5-methyl-2, 5′-anhydro-5, 6-dihydrouridine (7) .     

Synthesis of new aryl substituted furan-2(5H)-ones using the Suzuki-Miyaura reaction

A series of novel 5-arylidenefuran-2(5H)-ones and 5-arylidene-4-arylfuran-2(5H)-ones were synthesized via the Suzuki-Miyaura reactions of fimbrolide derivatives 5-(bromomethylene)furan-2(5H)-one and 4-bromo-5-(bromomethylene)furan-2(5H)-one, respectively. A regioselective Suzuki-Miyaura reaction on 4-bromo-5-(bromomethylene)furan-2(5H)-one allowed the synthesis of unsymmetrically substituted 5-arylidene-4-arylfuran-2(5H)-ones. The crystal structure of the intermediate 5-arylidene-4-bromofuran-2(5H)-one revealed interesting Br?O halogen bonding.     

Derivatives of M(η5-C5H5)2 (M = Mo,W) with alkenylpyridines and related ligands

Reactions of ligands 2-vinylpyridine 1, 4-vinylpyridine 2, 2-allylpyridine 3, 1-allylpyrazole 4, acrylonitrile 5 and allylcyanide 6 with the metallocene derivatives [Mo(η⁵-C₅H₅)₂H₃][PF₆] 7, [Mo(η⁵-C₅H₅)₂HI] 8, [W(η⁵-C₅H₅)₂H₃] [PF₆] 9, [Mo(η⁵-C₅H₅)₂H₂] 10, [M(η⁵-C₅H₅)₂Br₂], M = Mo 11, M = W 12 are described. Reaction of 7 with 1, 8 with 1, 3 with 8 and 4 with 8 gave mixtures of metallocyle isomers resulting from coordination of the nitrogen atom to molybdenum followed by internal hydrometallation; reaction of 11 with 1 gave an olefinic π complex; reaction of either 9 or 11 with 1 gave intractable oils; reactions of 8 with 2, 11 with 5, 12 with 5, 11 with 6 and 12 with 6 yielded monosubstituted products in which the ligand is N-coordinated.     

The synthesis and reactivity of rhenocene

Oxidation of lithiodicyclopentadienylrhenium by organic carbonyl compounds gives the complex (C₂₀H₂₀Re₂). Spectroscopic data show that this complex consists of two rhenocene fragments, {(C₅H)₅Re}, linked by a metal-metal bond, and so that it must be represented as a dimer of rhenocene, {(C₅H₅)Re}₂. Reaction of the dimer with benzyl bromide gives {(C₅H₅)₂ReCH₂C₆H₅} and {(C₅H₅₂ReBr}, while thermolysis gives the new dimeric complex {(C₅H₅)₂(C₅H₄)₂Re₂} and two equivalents of {(C₅H₅)ReH} and photolysis (λ ? 410 nm) gives [{η⁴- (C₅H₆)(C₅H₅)Re}{η⁵,η¹-(C₅H₄)(C₅H₅)Re}].     

Novel and efficient syntheses of 3′,5′-diamino derivatives of 2′,3′,5′-trideoxycytidine and 2′,3′,5′-trideoxyadenosine. Protonation behavior of 3′,5′-diaminonucleosides

High yielding synthetic routes to 3′,5′-diamino-2′,3′,5′-trideoxycytidine and 3′,5′-diamino-2′,3′,5′-trideoxyadenosine are described. In addition, the protonation behavior of 3′,5′-diamino-2′,3′,5′-trideoxycytidine, 3′,5′-diamino-2′,3′,5′-trideoxyadenosine, 3′,5′-diamino-3′,5′-dideoxythymidine, and 3′,5′-diamino-2′,3′,5′-trideoxyuridine has been studied by means of pH-metric measurements and NMR spectroscopy. The ionization constants and the sequence of protonation sites have been determined.     

Synthesis and Biological Activity of O‐Methyl Methyl 1‐(Substituted Phenoxyacetoxy)‐1‐(thien‐2‐yl)methylphosphinates

A series of novel O‐methyl methyl 1‐(substituted phenoxyacetoxy)‐1‐(thien‐2‐yl)methylphosphinates 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h were synthesized. Their structures were confirmed by IR, ¹H NMR, mass spectroscopy, and elemental analyses. The results of preliminary bioassays show that some of the title compounds exhibit moderate to good herbicidal and fungicidal activities. For example, the title compounds 5c , 5d , and 5g possess 90–100% inhibition against the tested plants at the concentration of 10 mg/L and 100 mg/L, whereas the title compounds 5a , 5b , 5c , and 5h possess 70–94% inhibition against Phyricularia grisea and Sclerotinia sclerotiorum at the concentration of 50 mg/L.     

Synthesis and Antimicrobial Screening of Some Novel Chromones and Pyrazoles with Incorporated Isoxazole Moieties

The title compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h and 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h have been synthesized from β‐diketones and chromones, respectively, having 5‐methyl‐3‐phenylisoxazole moiety. Substituted 2‐acetylphenyl 5‐methyl‐3‐phenylisoxazole‐4‐carboxylate 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h were converted into 1‐(2‐hydroxyphenyl)‐3‐(5‐methyl‐3‐phenylisoxazole‐4‐yl)propane‐1,3‐dione 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h by Baker–Venketaraman transformation. Further, the cyclodehydration of diketone 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h with glacial acetic acid in conc. HCl at reflux gave corresponding substituted 2‐(5‐methyl‐3‐phenylisoxazole‐4‐yl)‐4H‐chromen‐4‐one 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h . The corresponding 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h react with hydrazine hydrate in presence of glacial acetic acid in ethanol at reflux to furnish 2‐(5‐5(5‐methyl‐3‐phenylisoxazole‐4‐yl)‐1H‐pyrazole‐3‐yl)phenol 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h . The structures of all newly synthesized compounds have been confirmed by IR, ¹H NMR, mass spectral data, as well as elemental analysis. The synthesized compounds have been screened for their antimicrobial activity. Some of the compounds show better antimicrobial activity as compared with the reference drugs Streptomycin, Ampicillin, Gentamycin, Cefixime, and Ketoconazole.     

Synthesis of Novel 2‐Aryloxy‐3‐(4‐chlorophenyl)‐8‐substituted‐5‐aryl‐8,9‐dihydro‐3H‐chromeno[2,3‐d]pyrimidine‐4,6(5H,7H)‐dione Derivatives

Twenty‐one novel 2‐aryloxy‐3‐(4‐chlorophenyl)‐8‐substituted‐5‐aryl‐8,9‐dihydro‐3H‐chromeno[2,3‐d]pyrimidine‐4,6(5H,7H)‐diones 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o , 5p , 5q , 5r , 5s , 5t , 5u were designed and easily synthesized via a tandem aza‐Wittig reaction. Treatment of iminophosphorane 3 with 4‐chlorophenyl iso‐cyanate gave carbodiimide 4 , which reacted with phenols to provide the title compounds in 50–73% isolated yields. All compounds 3 and 5 were confirmed by infrared, ¹H‐NMR, mass spectra, and elemental analysis, and compound 5a was further analyzed by single‐crystal X‐ray diffraction, and the title compounds were synthesized with the purpose of bringing in some new chemical and biological interests.     

Synthesis and crystal and molecular structures of <Emphasis Type="Italic">N,N</Emphasis>′-methylenedipyridinium tetrachlorozincate(II) and <Emphasis Type="Italic">N,N</Emphasis>′-methylenedipyridinium tetrachlorocadmate(II)

Treatment of N,N′-methylenedipyridinium dichloride [C₅H₅N-CH₂-NC₅H₅]Cl₂ with MCl₂ (M = Zn or Cd) in aqueous solution gives the organic-inorganic hybrid ionic compounds [C₅H₅N-CH₂-NC₅H₅] · [MCl₄]. Both complex salts were fully characterised by multinuclear NMR spectroscopy, elemental analysis, and their molecular structures confirmed by powder X-ray diffraction studies. The most striking feature in both solid state structures was the presence of the C…Cl-M short contacts between the organic [C₅H₅N-CH₂-NC₅H₅] dication and inorganic [MCl₄] anion, which led to different crystal packing. For [C₅H₅N-CH₂-NC₅H₅]·[ZnCl₄], the C…Cl-Zn interactions led to the alternating arrangement of [C₅H₅N-CH₂-NC₅H₅]²⁺[ZnCl₄]²⁻ to form 1-D chains in the direction [010], and each individual chain had a two-fold rotational axis along the b axis, while for [C₅H₅N-CH₂-NC₅H₅] · [CdCl₄] the C…Cl-Cd associations gave 2-D network. In both solid state structures, the presence of Cl-ring centroid distances gave a strong indication of some form of Cl-π interactions.     

Peptidehelicenes in solution and gel: chiral discrimination through interactions between two types of helixes

Helical [5]thiaheterohelicene 5HM, which rapidly interconverts between P and M enantiomers in solution, was connected to helical l-phenylalanine oligomers with an ester linkage to give peptidehelicenes (5Fn, where n: number of bonded phenylalanines). The characteristics of 5F4 and 5F5 with two types of helixes in a molecule were investigated, particularly in comparison with those of 5F1–5F3 with an incomplete coil of a peptide moiety. l-Phenylalanine peptide chains induced a shift in the equilibrium between the P and M helixes of 5HM toward the P side for all the 5Fns examined. The enantiomeric excess (ee) of the P form increased with a decrease in temperature, together with an elongation of the peptide chains. 5F4 and 5F5 in hot solutions of some solvents formed a gel at room temperature, whereas 5F1–5F3 showed no such behavior. In this gel, the stable helical form of the 5HM moiety in 5F4 and 5F5 was observed to be the M form in contrast to that in their solutions.     

Design,Synthesis, and Characterization of 1, 3‐disubstituted‐1,4‐benzodiazepine Derivatives

The 2‐amino‐4′‐flouro‐benzophenone ( 1 ) that was reacted with chloroacetylchloride to afford 2‐chloro‐N‐(2‐(4′‐fluorobenzoyl) phenyl)acetamide ( 2 ) was subsequently converted to 1,4‐benzodiazepines ( 3 ) by the modification of the known hexamethylenetetramine based cyclization reaction developed by Blazevic and Kajfez. Thus, obtained product ( 3 ) was reacted with a variety of alkyl halide using KOH in DMF to give 1‐substituted‐5‐(4‐fluorophenyl)‐1H‐benzo[e][1,4]diazepin‐2(3H)‐one ( 4a , 4b ). To achieve 1, 3‐disubstituted 1, 4‐benzodiazepines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o , 5p , 5q , 5r , 5s , 5t ), 1‐substituted‐5‐(4‐fluorophenyl)‐1H‐benzo[e][1,4]diazepin‐2(3H)‐one ( 4a , 4b ) was treated with various aromatic aldehydes in the presence of KOH in toluene.     

Novel synthetic protocol toward pyrazolo[3,4‐h]‐[1,6]naphthyridines via Friedlander condensation of new 4‐aminopyrazolo[3,4‐b]pyridine‐5‐carbaldehyde with reactive α‐methylene ketones

Novel pyrazolo[3,4‐h][1,6]naphthyridine derivatives 6 , 8 , 9 , 11 , 13 , and 15 have been synthesized by Friedlander condensation of new 4‐amino‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine‐5‐carbaldehyde (o‐aminoaldehyde) 4 with active methylene ketones, such as symmetric acetone 5a , monoalkylketones 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , unsymmetrical dialkyl ketones 7a , 7b , p‐bromophenylacetonitrile 10 , β‐ketoester 12a , β‐ketoamide 12b , or diethyl malonate 14 , respectively. J. Heterocyclic Chem., (2011).