Production of Dihydrogen Using Ammonia Borane as Reagent and Pyrazole as Catalyst

Theoretical chemistry (DLPNO-CCSD(T)/def2-TZVP//M06-2x/aug-cc-pVDZ) was used to design a system based on ammonia boranes catalyzed by pyrazoles with the aim of producing dihydrogen, nowadays of high interest as clean fuel. The reactivity of ammonia borane and cyclotriborazane were investigated, including catalytic activation through 1H-pyrazole, 4-methoxy-1H-pyrazole, and 4-nitro-1H-pyrazole. The results point toward a catalytic cycle by which, at the same time, ammonia borane can initially store and then, through catalysis, produce dihydrogen and amino borane. Subsequently, amino borane can trimerize to form cyclotriborazane that, in presence of the same catalyst, can also produce dihydrogen. This study proposes therefore a consistent progress in using environmentally sustainable (metal free) catalysts to efficiently extract dihydrogen from small B−N bonded molecules.     

1H, 13C NMR, X-ray and conformational studies of new 1-alkyl-3-benzoyl-pyrazole and 1-alkyl-3-benzoyl-pyrazoline derivatives

The (1)H and (13)C NMR resonances of 22 1-alkyl-pyrazole and 25 1-alkyl-pyrazoline derivatives were assigned completely using the concerted application of one- and two-dimensional experiments (DEPT, gs-HMQC and gs-HMBC). Nuclear Overhauser enhancement (NOE) effects, conformational analysis and X-ray crystallography confirm the preferred conformation of those compounds.     

Polymerizing cluster helicates into high-connectivity networks

Solvothermal reactions of CuII salts and 3,5-bis(4-pyridyl)pyrazole (HL) under various conditions gave three different types of crystalline compound, namely [Cu2(Cu5L6)]BF(4).5 H2O (1 a), [Cu2(Cu5L6)]ClO(4).5 H2O (1 b), and [Cu7(CN)2(Cu5L6)2][BF4]3 (2). 1 a and b were obtained in ethanol and NH3.H2O, whereas 2 was obtained in methanol and NH3.H2O. The three complexes were constructed by incorporating new pentanuclear copper(I) pyrazolate bis(triple helical) cluster helicates (Cu5L6) as the second building units (SBUs), in which as many as twelve 4-pyridyl N atoms are available for further coordination and construction of high-connectivity topological networks. In 1 a and b, seven 4-pyridyl N atoms are linked to three three-coordinated CuI atoms and four four-coordinated CuI atoms, which results in 3,4,7-connected networks. In 2, as many as eleven 4-pyridyl N atoms coordinate to eleven CuI atoms, which results in a 4,10-connected topological network. The increasing connectivity of the cluster nodes in 2 is closely related to the in situ-formed CN- anion bridge around the periphery of the pentanuclear cluster helicates. The luminescenct properties of these compounds were also investigated.     

新型含吡唑基的查尔酮的合成、表征及晶体结构

以2种1-苯基-3-甲基-5-对甲苯氧基-吡唑-4-甲醛为原料, 在强碱条件下与苯乙酮(取代苯乙酮)发生羟醛缩合, 高产率地合成出10种新型含吡唑基的查尔酮. 化合物的结构经元素分析, IR和¹H NMR确认. 并用X射线衍射法测定了化合物4c的晶体结构. 化合物4c属三斜晶系, 空间群P-1, 晶胞参数: a＝1.0225(2) nm, b＝1.4263(3) nm, c＝1.6718(3) nm, α＝110.32(3)°, β＝106.30(3)°, γ＝98.11(3)°, M_r＝428.90, V＝2.1159(7) nm³, D_c＝1.346 Mg/m³, Z＝2, F(000)＝896.     

Effect of N1-substituted pyrazolic hybrid ligands on palladium catalysts for the Heck reaction

In this paper we have explored the influence of several linkers present on the [PdCl₂(L)] complexes, where L is 3,5-dimethylpyrazolic hybrid ligand N1-substituted by polyether chains and/or phenyl groups. These complexes have been used as pre-catalysts in the Heck reaction between phenyl halides and tert-butyl acrylate. The corresponding complexes efficiently catalyze the Heck olefination and provide good yields under phosphine-free conditions, even for aryl chlorides. Different reaction conditions were investigated and it was found that the nature of the ligand has an important influence on the effectiveness of the catalytic system. Ligand 1,8-bis(3,5-dimethyl-1H-pyrazol-1-yl)-3,6-dioxaoctane (L1), which has previously shown to be the most flexible and versatile, achieved high turnover numbers within very short reaction times and low catalyst loadings.     

吡唑腙及其双杂环化合物的设计、合成及生物活性

利用Vilsmeier-Haak反应得到活性中间体,取代-4-甲酰基吡唑;将其与芳氧乙酰肼反应,合成5个吡唑腙类化合物3,再经关环反应,制得5个吡唑类双杂环化合物4。所有新化合物的结构均经IR,1H NMR,MS和元素分析确证了结构。对新化合物3,4分别进行了棉花枯萎病菌、棉花黄萎病菌、棉花立枯病菌、瓜果腐霉病菌、番茄早疫病菌、向日葵菌核病菌等初步的抑菌活性测试,结果表明,吡唑类双杂环化合物4的抑菌效果明显高于吡唑腙化合物3。在质量浓度为50mg/L时,3d、3e对番茄早疫病菌、向日葵菌核病菌有较好的抑制效果(﹥80%);双杂环化合物4对6种病菌均有明显的抑制效果(﹥70%),其中4d、4e对棉花立枯病菌的抑制率大于95%。     

Synthesis, characterization and antitumor activity of novel N-substituted α-amino acids containing ferrocenyl pyrazole-moiety

A series of new N-[(3-ferrocenyl-1-phenylpyrazol-4-yl)methyl] α-amino acids were prepared and characterized by a range of spectroscopic techniques and cyclic voltammetry. The in vitro antitumor activity of all synthesized compounds was investigated against cervix adenocarcinoma HeLa, melanoma Fem-x and myelogenous leukemia K562 cell lines using the MTT method. Tryptophan derivative 1l exhibited the highest cytotoxic activity in the cell growth inhibition of all three types of cell lines.     

Synthesis and Crystal Structure of 7-Ethoxycarbonyl-2-methyl-6-methylthio-lH-imidazo[1,2-b]pyrazole

The title compound 7-ethoxycarbonyl-2-methyl-6-methylthio-1H-imidazo[1,2-b]-pyrazole (Mr = 239.29) was synthesized and structurally characterized by IR, 1H NMR and single-crystal X-ray diffraction. It belongs to the triclinic system, space group P1, with a = 8.0461(10), b = 8.5534(11), c = 9.5605(12) A, α = 64.804(2), β = 74.231(2), γ = 76.885(2)°, V= 568.27(12) A3, Z = 2, Dc = 1.398 g/cm3,μ= 0.274 mm-1, F(000) = 252, the final R.= 0.0454 and wR = 0.1261. A total of 3360 reflections were collected, of which 2466 were independent (Rint = 0.0138) and 2154 were observed with I > 2σ(Ⅰ).     

Synthesis and Crystal Structure of 3-{[（1E） 1-（2- Hydroxyphenyl） methylidene]amino}-4-cyanopyrazole

The title Schiff base compound （C11H8N4O）, a derivative of pyrazole, has been synthesized by the reaction of salicylaldehyde and 3-amino-4-cyanopyrazole in absolute ethanol and characterized by elemental analyses, IR, ^1H NMR and X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P21/n, with a = 7.5594（7）, b = 18.3342（19）, c = 22.461（2） A^°, β = 98.419（2）°, V = 3079.5（5） A^°3, Mr = 212.21, Z = 12, F（000） = 1320, Dc = 1.373 g/cm^3, T = 298（2） K, 2 = 0.71073 A^°, the final R = 0.0571 and wR = 0.0493. A total of 5412 unique reflections were collected, of which 1612 with I 〉 2σ（I） were observed. The molecular structure adopts a trans configuration about the C=N double bond. The preliminary biological tests show that the compound has high antibacterial activities.