One‐Pot Synthesis of Pyrimido[1,2‐a]benzimidazoles under Solvent‐Free Conditions

A series of pyrimido[1,2‐a]benzimidazoles were obtained from aldehydes, 2‐aminobenzimidazole and ethyl acetoacetate in good‐to‐excellent yields by a simple, mild, and efficient procedure utilizing N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide (TBBDA) and poly(N‐bromo‐N‐ethylbenzene‐1,3‐disulfonamide) (PBBS) as catalysts.     

Synthesis of N,N,N-4,4＂-Di-（4-methylphenyl）-2,2＇：6＇,2＂- terpyridine-N,N,N-tris（isothiocyanato） Ruthenium（Ⅱ） and Application to Colorimetric Hg^2＋ Sensor

A terpyridine derivative DPTP [di-（4-methylphenyl）-2,2＇：6＇,2＂-terpyridine] was conveniently synthesized from 2-bromopyridine via halogen-dance reaction, Kharash coupling and Stille coupling reaction. Then its corresponding ruthenium complex Ru-DPTP [N,N,N-4,4＇＇-di-（4-methy,phenyl）-2,2＇：6＇,2＂-terpyridine-N,N,N-tris（is,-thi,cyanat,）- ruthenium（H） ammonium] was obtained and fully characterized by IR, UV-Vis, ESI MS and elemental analysis. The MLCT absorption band of Ru-DPTP was blue-shifted from 570 to 500 nm upon addition of Hg^2＋. Among a series of surveyed metal ions, the complex showed a unique recognition to Hg^2＋, indicating that it can be used as a selective colorimetric sensor for Hg^2＋.     

Synthesis of 1,3‐Selenazol‐2(3H)‐imines

The reaction of N,N′‐diarylselenoureas 16 with phenacyl bromide in EtOH under reflux, followed by treatment with NH₃, gave N,3‐diaryl‐4‐phenyl‐1,3‐selenazol‐2(3H)‐imines 13 in high yields (Scheme 2). A reaction mechanism via formation of the corresponding Se‐(benzoylmethyl)isoselenoureas 18 and subsequent cyclocondensation is proposed (Scheme 3). The N,N′‐diarylselenoureas 16 were conveniently prepared by the reaction of aryl isoselenocyanates 15 with 4‐substituted anilines. The structures of 13a and 13c were established by X‐ray crystallography.     

Axially Dissymmetric Chiral (R)‐N,W‐Bis(2‐hydroxy‐3,5‐ditert‐butyl‐arylmethyl)‐1, 1′‐binaphthalene‐2,2′‐diamine as Chiral Ligands in the Reaction of Diethylzinc to Aldehydes†

Chiral ligand (A)‐N,N′‐Bis(2‐hydroxy‐3,5‐di‐tert‐butyl‐arylmethyl)‐1,1′‐binaphthalene‐2,2′‐diamine derived from the reduction of Schiff base (R)‐2,2′‐bis (3,5‐di‐tert‐butyl‐2‐hydroxybenzylideneamino)‐1, 1′‐binaphthyl with LiAlH₄, is fairly effective in the asymmetric addition reaction of diethylzinc to aldehydes by which good yields (46%‐94%) of the corresponding sec‐alcohols can be obtained in moderate ee (51%‐79%) with R configuration for a variety of aldehydes.     

Synthesis and characterization of diphenylaminodiphenyl stryl based alternating copolymers

Diphenylaminobiphenylated stryl based alternating copolymers with phenyl or fluorene, which were expected to have a terphenylene vinylene backbone containing an (N,N‐diphenylamino)biphenyl pendant and a phenyl/fluorene/phenylene vinylene backbone containing an (N,N‐diphenylamino)biphenyl pendant, were synthesized by a Suzuki coupling reaction. The obtained copolymers were confirmed with various types of spectroscopy. The alternating copolymers showed good hole‐injection properties because of their low oxidation potential and good solubility and high thermal stability with a high glass‐transition temperature. The alternating copolymers showed blue emissions because of the adjusted conjugation lengths; the maximum wavelength was 460 nm for poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐5‐(2′‐ethylhexyloxy)‐2‐methoxybenzene} and 487 nm for poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl] vinylene‐alt‐9,9‐dihexylfluorene}. The maximum brightness of indium tin oxide/poly(3,4‐ethylene dioxythiophene)/polymer/LiF/Al devices with poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐5‐(2′‐ethylhexyloxy)‐2‐methoxybenzene} or poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐9,9‐dihexylfluorene} as the emitting layer was 250 or 1000 cd/m², respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 341–347, 2007     

Microsolvated and Chelated Butylzinc Cations: Formation,Relative Stability,and Unimolecular Gas‐Phase Chemistry

Solutions of butylzinc iodide in tetrahydrofuran, acetonitrile, and N,N‐dimethylformamide were analyzed by electrospray ionization mass spectrometry. In all cases, microsolvated butylzinc cations [ZnBu(solvent)_n]⁺, n=1–3, were detected. The parallel observation of the butylzincate anion [ZnBuI₂]^? suggests that these ions result from disproportionation of neutral butylzinc iodide in solution. In the presence of simple bidentate ligands (1,2‐dimethoxyethane, N,N‐dimethyl‐2‐methoxyethylamine, and N,N,N′,N′‐tetramethylethylenediamine), chelate complexes of the type [ZnBu(ligand)]⁺ form quite readily. The relative stabilities of these complexes were probed by competition experiments and analysis of their unimolecular gas‐phase reactivity. Fragmentation of mass‐selected [ZnBu(ligand)]⁺ leads to the elimination of butene and formation of [ZnH(ligand)]⁺. In marked contrast, the microsolvated cations [ZnBu(solvent)_n]⁺ lose the attached solvent molecules upon gas‐phase fragmentation to produce bare [ZnBu]⁺, which subsequently dissociates into [C₄H₉]⁺ and Zn. This difference in reactivity resembles the situation in organozinc solution chemistry, in which chelating ligands are needed to activate dialkylzinc compounds for the nucleophilic addition to aldehydes.     

Synthesis of 4‐fluoroalkyl‐2H‐pyrido [1, 2‐a] pyrimidin‐2‐ones from 2, 2‐dihydropolyfluoroalkanoic acids

In the presence of N, N′‐dicyclohexylcarbodiimide, 2‐aminopyridine and its derivatives (2) condensed with 2, 2‐di‐hydropolyfluoroalkanoic adds (1) to give the corresponding amides. Subsequent intramolecular Micheal addition‐elimination reactions of the fluorine‐containing amides under basic conditions gave 4‐fluoroalkyl‐2H‐pyrido[1,2‐a]pyrimidin‐2‐ones (3) in good yields.     

Reactivity of ortho‐Substituted Aryl–Palladium Complexes towards Carbodiimides,Isothiocyanates, Nitriles,and Cyanamides

Complexes [Pd(C₆H₃XH‐2‐R′‐5)Y(N^N)] (X=O, NH; Y=Br, I; R′=H, NO₂; N^N=N,N,N′,N′‐tetramethylethylenediamine (tmeda), 2,2′‐bipyridine (bpy), 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (dtbbpy)) react with RN?C?E (E=NR, S) or RC≡N (R=alkyl, aryl, NR′′₂) and TlOTf (OTf=CF₃SO₃) to give, respectively, 1) products of the insertion of the C?E group into the C? Pd bond, protonation of the N atom, and coordination of X to Pd, [Pd{κ²‐X,E‐(XC₆H₃{EC(NHR)}‐2‐R′‐4)}(N^N)]OTf or [Pd(κ²‐X,N‐{ZC₆H₃(NH?CR)‐2‐R′‐4})(N^N)]OTf, or products of the coordination of carbodiimides and OH addition, [Pd{κ²‐C,N‐(C₆H₄{OC(NR)}NHR‐2)}(bpy)]OTf; or 2) products of the insertion of the C≡N group to Pd and N‐protonation, [Pd(κ²‐X,N‐{XC₆H₃(NH?CR)‐2‐R′‐4})(N^N)]OTf.     

An Efficient and Economical Method for the Preparation of Fmoc-Argω,ω'(Boc)2-OH

The arginine derivative Fmoc‐Arg^ω,ω′(Boc)₂‐OH has been prepared in perfect yield starting from Fmoc‐Orn·HCl and N,N′‐di‐Boc‐N′′‐triflyguanidine with the presence of diisopropylethylamine (DIEA). This work provides an efficient and economical method for the preparation of this compound.     

Synthesis of New C2‐Symmetric Chiral Bisamides from (1S,2S)‐Cyclohexane‐1,2‐dicarboxylic Acid

A series of new C₂‐symmetric (1S,2S)‐cyclohexane‐1,2‐dicarboxamides was synthesized from (1S,2S)‐cyclohexane‐1,2‐dicarbonyl dichloride and N‐benzyl‐substituted aromatic amines, which were prepared from 2‐aminopyridine, 2‐chloroaniline, and 2‐aminophenol via imine formation with benzaldehyde and subsequent reduction with NaBH₄. (1S,2S)‐N,N′‐Dibenzyl‐N,N′‐bis[2‐(benzyloxy)phenyl]cyclohexane‐1,2‐dicarboxamide was converted to (1S,2S)‐N,N′‐dibenzyl‐N,N′‐bis(2‐hydroxyphenyl)cyclohexane‐1,2‐dicarboxamide via hydrogenolysis in the presence of Pd(OH)₂ on active carbon powder.     

N,N,N′,N′‐Tetrabromobenzene‐1,3‐Disulfonamide and Poly(N‐Bromo‐N‐Ethyl‐Benzene‐1,3‐Disulfonamide) as Efficient Catalysts for the Methoxymethylation of Alcohols under Solvent‐Free Conditions

Methoxymethylation of a variety of alcohols was performed using formaldehyde dimethyl acetal in the presence of N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide [TBBDA] and poly(N‐bromo‐N‐ethylbenzene‐1,3‐disulfonamide) [PBBS] as catalysts at room temperature and solvent‐free conditions. The methoxymethyl ethers (MOM‐ethers) were obtained with good to excellent yields.     

Synthesis and biological activity of novel N‐benzoyl‐N‐tert‐butyl‐N′‐(β‐triphenylgermyl)propionylhydrazines

A series of new N‐benzoyl‐N‐tert‐butyl‐N′‐(β‐triphenylgermyl)propionylhydrazines were synthesized by the condensation reaction of β‐triphenylgermyl propanoic acid with N‐benzoyl‐N‐tert‐butylhydrazines in good yields by using N,N′‐dicyclohexylcorbodiimide as dehydrating agent. These title compounds were evaluated for molting hormone mimicking activity. The results of bioassay showed that the compounds exhibit moderate larvicidal activity, and toxicity assays indicated that the title compounds can induce a premature, abnormal and lethal larval molt. We found that the title compounds possess potential anticancer activities in vitro. Copyright © 2002 John Wiley & Sons, Ltd.     

Efficient asymmetric addition of diethylzinc to aldehydes using C2‐novel chiral pyridine β‐amino alcohols as chiral ligands

A series of novel C₂‐symmetric chiral pyridine β‐amino alcohol ligands have been synthesized from 2,6‐pyridine dicarboxaldehyde, m‐phthalaldehyde and chiral β‐amino alcohols through a two‐step reaction. All their structures were characterized by ¹H NMR, ¹³C NMR and IR. Their enantioselective induction behaviors were examined under different conditions such as the structure of the ligands, reaction temperature, solvent, reaction time and catalytic amount. The results show that the corresponding chiral secondary alcohols can be obtained with high yields and moderate to good enantiomeric excess. The best result, up to 89% ee, was obtained when the ligand 3c (2S,2′R)‐2,2′‐((pyridine‐2,6‐diylbis(methylene))bisazanediyl))bis(4‐methyl‐1,1‐diphenylpentan‐1‐ol) was used in toluene at room temperature. The ligand 3g (2S,2′R)‐2,2′‐((1,3‐phenylenebis(methylene))bis(azanediyl))bis(4‐methyl‐1,1‐diphenylpentan‐1‐ol) was prepared in which the pyridine ring was replaced by the benzene ring compared to 3c in order to illustrate the unique role of the N atom in the pyridine ring in the inductive reaction. The results indicate that the coordination of the N atom of the pyridine ring is essential in the asymmetric induction reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Mild Oxidation of 1,3,5‐Trisubstituted Pyrazolines with N‐Bromo‐sulphonamides

1,3,5‐Trisubstituted pyrazolines to pyrazoles are carried out efficiently in the presence of new reagents N,N,N′, N′‐tetrabromo‐benzene‐1,3‐disulfonylamine [TBBDA] and N,N′‐dibromo‐N,N′‐1,2‐ethanediylbis‐(p‐toluenesulphonamide) [BNBTS] in solvent‐free conditions with catalytic amounts of SiO₂ under microwave irradiation in high yields.     

Synthesis and characterization of a novel organic–inorganic hybrid salt and its application as a highly effectual Brønsted–Lewis acidic catalyst for the production of N,N′‐alkylidene bisamides

In this research, a novel organic–inorganic hybrid salt, namely, N¹,N¹,N²,N²‐tetramethyl‐N¹,N²‐bis(sulfo)ethane‐1,2‐diaminium tetrachloroferrate ([TMBSED][FeCl₄]₂) was prepared and characterized by Fourier‐transform infrared spectroscopy (FT‐IR), energy‐dispersive X‐ray spectroscopy (EDX), elemental mapping, field emission scanning electron microscopy (FE‐SEM), X‐ray diffraction (XRD), thermal gravimetric (TG), differential thermal gravimetric (DTG), and vibrating‐sample magnetometry (VSM) analyses. Catalytic activity of the hybrid salt was tested for the synthesis of N,N′‐alkylidene bisamides through the reaction of benzamide (2 eq.) and aromatic aldehydes (1 eq.) under solvent‐free conditions in which the products were obtained in high yields and short reaction times. The catalyst was superior to many of the reported catalysts in terms of two or more of these factors: the reaction medium and temperature, yield, time, and turnover frequency (TOF). [TMBSED][FeCl₄]₂ is a Brønsted–Lewis acidic catalyst; there are two SO₃H groups (as Brønsted acidic sites) and two tetrachloroferrate anions (as Lewis acidic sites) in its structure. Highly effectiveness of the catalyst for the synthesis of N,N′‐alkylidene bisamides can be attributed to synergy of the Brønsted and Lewis acids and also possessing two sites of each acid.     

A new one‐dimensional CdII coordination polymer with a two‐dimensional layered structure incorporating 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,2‐dicarboxylate ligands

The N‐heterocyclic ligand 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and interesting properties. In the coordination polymer catena‐poly[[cadmium(II)‐bis[μ‐benzene‐1,2‐dicarboxylato‐κ⁴O¹,O^1′:O²,O^2′]‐cadmium(II)‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole}‐κ²N²:N³;κ²N³:N²] dimethylformamide disolvate], {[Cd(C₈H₄O₄)(C₁₁H₁₀N₄)]·C₃H₇NO}_n, (I), each Cd^II ion exhibits an irregular octahedral CdO₄N₂ coordination geometry and is coordinated by four O atoms from two symmetry‐related benzene‐1,2‐dicarboxylate (1,2‐bdic²⁻) ligands and two N atoms from two symmetry‐related imb ligands. Two Cd^II ions are connected by two benzene‐1,2‐dicarboxylate ligands to generate a binuclear [Cd₂(1,2‐bdic)₂] unit. The binuclear units are further connected into a one‐dimensional chain by pairs of bridging imb ligands. These one‐dimensional chains are further connected through N—H…O hydrogen bonds and π–π interactions, leading to a two‐dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairs via weak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.     

Dinuclear Complexes of Copper(I) with Crown Ether‐containing N‐Thiophosphorylated Bis‐thioureas and 2,2′‐Bipyridine or 1,10‐Phenanthroline: Synthesis,Characterization, and Picrate Extraction Properties

Reaction of O,O′‐diisopropylthiophosphoric acid isothiocyanate (iPrO)₂P(S)NCS with 1,10‐diaza‐18‐crown‐6, 1,7‐diaza‐18‐crown‐6, or 1,7‐diaza‐15‐crown‐5 leads to the N‐thiophosphorylated bis‐thioureas N,N′‐bis[C(S)NHP(S)(OiPr)₂]‐1,10‐diaza‐18‐crown‐6 ( H₂L^I ), N,N′‐bis[C(S)NHP(S)(OiPr)₂]‐1,7‐diaza‐18‐crown‐6 ( H₂L^II ) and N,N′‐bis[C(S)NHP(S)(OiPr)₂]‐1,7‐diaza‐15‐crown‐5 ( H₂L^III ). Reaction of the potassium salts of H₂L^I–III with a mixture of CuI and 2,2′‐bipyridine ( bpy ) or 1,10‐phenanthroline ( phen ) in aqueous EtOH/CH₂Cl₂ leads to the dinuclear complexes [Cu₂(bpy)₂L^I–III] and [Cu₂(phen)₂L^I–III] . The structures of these compounds were investigated by ¹H, ³¹P{¹H} NMR spectroscopy, and elemental analysis. The crystal structures of H₂L^I and [Cu₂(phen)₂L^I] were determined by single‐crystal X‐ray diffraction. Extraction capacities of the obtained compounds in comparison to the related compounds 1,10‐diaza‐18‐crown‐6, N,N′‐bis[C(=CMe₂)CH₂P(O)(OiPr)₂]‐1,10‐diaza‐18‐crown‐6, N,N′‐bis[C(S)NHP(O)(OiPr)₂]‐1,10‐diaza‐18‐crown‐6 towards the picrate salts LiPic, NaPic, KPic. and NH₄Pic were also studied.     

Synthesis of Aib‐ and Phe(2Me)‐Containing Cyclopentapeptides

Some recently described pentapeptides containing the α,α‐disubstituted α‐amino acids Aib and Phe(2Me) have been cyclized in DMF solution using diphenyl phosphorazidate (DPPA), O‐(1H‐benzotriazol‐1‐yl)‐N,N,N′,N′‐tetamethyluronium tetrafluoroborate/1‐hydroxybenzotriazole (TBTU/HOBt), and diethyl phosphorocyanidate (DEPC), respectively, to give the corresponding cyclopentapeptides in fair‐to‐good yields. In the case of peptides with L ‐amino acids, and (R)‐ and (S)‐Phe(2Me), the yields differed significantly in favor of the L /(R) combination. The conformations in the crystals of cyclo(Gly‐Aib‐(R,S)‐Phe(2Me)‐Aib‐Gly) and cyclo(Gly‐(R)‐Phe(2Me)‐Pro‐Aib‐Gly) have been determined by X‐ray crystallography, leading to quite different results. In the latter case, the conformation in solution has been elucidated by NMR studies.     

Preparation of amphiphilic statistical copolymers of 2‐hydroxyethyl methacrylate with 2‐diethylaminoethyl methacrylate,precursors of water‐soluble copolymers

Statistical copolymers of 2‐hydroxyethyl methacrylate (HEMA) and 2‐diethylaminoethyl methacrylate (DEA) were synthesized at 50 °C by free‐radical copolymerization in bulk and in a 3 mol L^?1 N,N′‐dimethylformamide solution with 2,2′‐azobisisobutyronitrile as an initiator. The solvent effect on the apparent monomer reactivity ratios was attributed to the different aggregation states of HEMA monomer in the different solvents. The copolymers obtained were water‐insoluble at a neutral pH but soluble in an acidic medium when the molar fraction of the DEA content was higher than 0.5. The quaternization of DEA residues increased the hydrophilic character of the copolymers, and they became water‐soluble at a neutral pH when the HEMA content was lower than 0.25. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2427–2434, 2002     

N-(4-甲基苯甲酰氨基) N’-[5-(2-三氟甲基苯基)-2-呋喃甲酰硫脲的合成、晶体结构测定与生物活性测定

本文首次合成标题化合物N-(4-甲基苯甲酰氨基)-N’-[5-(2-三氟甲基苯基)-2-呋喃甲酰硫脲。化合物(C21H16F3N3O3S, Mr = 447.43)单晶经测定为单斜晶体,空间群为P -1。在晶体中,存在一些分子内和分子间的相互作用,分子间还有C—H···π 的相互作用,这可能导致晶体更稳定的原因。目标产物的结构经IR, H NMR和元素分析测定确证。初步生物活性测试表明,部分化合物对棉花枯萎病、黄瓜灰霉病、苹果轮纹病和棉花炭疽病有较好的选择性杀菌活性;部分目标化合物有较好的除草活性。