Novel Synthesis of Dihydroquinoxalinylpyridazine Derivatives

Methylquinoxaline derivative 1 undergoes bromination to give bromomethyl quinoxaline 2 , which could be transferred to cyanomethyl quinoxaline 3 . The latter compound 3 readily coupled with arene diazonium salts to give hydrazone derivatives 5a‐c . Compounds 5a,b reacted with active methylene reagents to give the target ring system, quinoxalinylpyridazine derivatives 8a‐c . Compound 1 reacted with DMFDMA to give the enamine derivative 9 , which coupled with arene diazonium salts to give the aldehydic hydrazone derivatives 10a‐c . Compound 10 reacted with active methylene compounds to give quinoxalinylpyridazine derivatives. UV characterization of some of the prepared compounds was reported.     

Synthesis and antibacterial activity of some novel thieno[2,3-c]pyridazines using 3-amino-5-phenyl-2-ethoxycarbonylthieno[2,3-c]pyridazine as a starting material

3-Amino-5-phenyl-2-ethoxycarbonylthieno[2,3-c]pyridazine (6) was prepared by reaction of 4-cyano-6-phenylpyridazine-3(2H)-thione (4) with ethyl chloroacetate in the presence of sodium ethoxide. Hydrazinolysis of compound 6 yielded the corresponding carbohydrazide, (9) which on treatment with acetylacetone and ethyl acetoacetate produced the novel thieno[2,3-c]pyridazines (10 and 11). Treatment of compound 9 with nitrous acid yielded the corresponding carboazide (13), which upon boiling in toluene furnished imidazo[4′,5′:4,5]thieno[2,3-c]pyridazine (15). Pyrimidothienopyridazines (16–18) were achieved by cyclocondensation of compound 9 with some reagents, namely acetic anhydride, formic acid, and triethyl orthoformate. The newly synthesized compounds were confirmed by elemental analyses and spectral data. The antibacterial activities of the new compounds were also evaluated.     

Spiroheterocyclic compounds: old stories with new outcomes

An efficient and straightforward method for the preparation of spirodiazine derivatives is reported which involves mild reaction conditions and easily accessible reactants. A new class of spiroazaheterocycles, spiro[pyrrolidine-pyrrolo[3,4-c]pyrroles], is obtained. A feasible explanation is given for the unexpected results obtained at high energy (high temperatures, MW and ultrasound irradiation).     

Synthesis, Crystal Structures and Properties of Two Copper (II) Complexes with Pyridazine Derivative Ligand

Abstract  Two new complexes, [Cu(L)₂(CH₃OH)] · (ClO₄)₂ (1) and [Cu(L)₂(H₂O)] · (NO₃)₂ (2), have been synthesized and their crystal structures have been determined by X-ray analysis, where L = 3-(3,5-bimethylpyrazole-yl)-6-chloro-pyridazine]. The complex 1 crystallizes in the monoclinic, space group C2/c, and the coordination configuration of copper (II) is better described as trigonal pyramidal geometry with four N atoms from L and one O_methanol^. The coordination configuration of 2 is quite similar to that of 1 except O_water instead of O_methanol^. The intermolecular hydrogen bonds link the repeat units and extend the molecules to multinuclear structures in both compounds. The spectral properties of the title compounds have been studied and discussed. Furthermore, the antibacterial activities of the title compounds have been detected, the results indicate that the ligands and two copper(II) complexes exhibit certain fungicidal activities again several bacteria. Index Abstract  Two new complexes, [Cu(L)2(CH3OH)]·(ClO4)2 (1) and [Cu(L)2(H2O)]·(NO3)2 (2), have been synthesized and their crystal structures have been determined by X-ray analysis, where L= 3-(3,5-bimethylpyrazole-yl)-6-chloro-pyridazine. The intermolecular hydrogen bonds extend the molecules to multinuclear structures in both compounds.      

Predicting and researching adsorption configurations of pyridazine on Si(100) surface by means of X-ray spectroscopies in theory

The landscape of organic molecule on Si(100) surface has a great significance for organic functionalisation of Si semiconductor. Several possible adsorption configurations for pyridazine on Si(100) surface have been forecasted by systemic comparison and investigation. The C1s XPS and NEXAFS spectra of these adsorption systems based on density functional theory and full core-hole potential approximation have been calculated. Although the sensibility of XPS to these adsorption configurations is not very strong, these configurations can be absolutely distinguished by NEXAFS spectra, which will bring tremendous reference to the future experimental study. Mode II, III, V and VI have a significantly higher adsorption energy, which are most likely to be present in experiment. In addition, we have made the research on specific sources of the peaks in spectra by analysing their decomposed NEXAFS spectra, the results show that the Carbon atoms which do not bond to surface atoms, make the most contribute to the intensity of characteristic peaks in spectra.     

New Approaches for the Synthesis of Thiazoles and Their Fused Derivatives with Antimicrobial Activities

The 2‐ethoxy carbonyl methylene thiazol‐4‐one ( 3 ) reacts with acetophenone ( 4 ) to give the ethyl 2‐(4‐oxo‐4,5‐dihydro‐thiazol‐2‐yl)‐3‐phenyl‐2‐butenoate ( 5 ). The reactivity of the latter product towards aromatic aldehydes 6a‐d , cyanomethylene reagents 9a,b , aromatic aldehydes 13a‐d , phenylisothiocyanate ( 16 ), elemental sulfur and aromatic amines ( 20a‐c ) was studied to give arylidene, pyridine, thiophene and anilide derivatives. Some of the newly synthesized derivatives were used to synthesize fused derivatives. The antimicrobial activities of the newly synthesized products were tested in vitro for antimicrobial activity against two bacterial isolates, one saprophytic (Escherichia coli) and the other parasitic (Xanthomonas citri) and for antifungal activity against one saprophytic (Aspergillus fumigatus) and two phytopathogenics (Rhizoctonia solani and Fusarium oxysporum).     

邻二氮杂苯-水复合物氢键相互作用的理论研究

The hydrogen bond structure and interaction energy on the ground state of pyridazine and water complex are studied with B3LYP and MP2 method. All calculations show that there are strong interactions for a hydrogen bond N…H-O and large red-shifts for the symmetric H-O stretching vibrational frequencies in the pyridazine and water complex. The first singlet 1(n, π ) and 1(π,π) vertical excitations of the monomer pyridazine and the hydrogen bond between a pyridazine molecule and a water molecule have been investigated with time-dependent density functional theory TDB3LYP method.     

Novel pyrrole C-nucleosides by nitrogen extrusion from pyridazine C-nucleosides

Pyridazine C-nucleosides have been synthesized by [4+2] cycloaddition of alkynyl C-nucleosides with substituted tetrazines. These pyridazines on extrusion of a nitrogen atom afforded novel pyrrole C-nucleosides with good yields. The results of electrochemical and chemical reduction are compared.     

Chemistry, commentary, and community: discussion of “an examination of the vaporization enthalpies and vapor pressures of pyrazine, pyrimidine, pyridazine, and 1,3,5-triazine” by Lipkind and Chickos

Vaporization enthalpies for the isomeric diazines were discussed within the context of recent measurements and estimation techniques. It is suggested that pyridazine shows enigmatic behavior.

Spectral, structural and DFT studies of platinum group metal 3,6-bis(2-pyridyl)-4-phenylpyridazine complexes and their ligand bonding modes

Reactions of 3,6-bis(2-pyridyl)-4-phenylpyridazine (L^ph) with [(η⁶-arene)Ru(μ-Cl)Cl]₂ (arene = C₆H₆, p-ⁱPrC₆H₄Me and C₆Me₆), [(η⁵-C₅Me₅)M(μ-Cl)Cl]₂, (M = Rh and Ir) and [(η⁵-Cp)Ru(PPh₃)₂Cl] (Cp = C₅H₅, C₅Me₅ and C₉H₇) afford mononuclear complexes of the type [(η⁶-arene)Ru(L^ph)Cl]PF₆, [(η⁵-C₅Me₅)M(L^ph)Cl]PF₆ and [(Cp)Ru(L^ph)(PPh₃)]PF₆ with different structural motifs depending on the π-acidity of the ligand, electronic properties of the central metal atom and nature of the co-ligands. Complexes [(η⁶-C₆H₆)Ru(L^ph)Cl]PF₆1, [(η⁶-p-ⁱPrC₆H₄Me)Ru(L^ph)Cl]PF₆2, [(η⁵-C₅Me₅)Ir(L^ph)Cl]PF₆5, [(η⁵-Cp)Ru(PPh₃)(L^ph)]PF₆, (Cp = C₅H₅, 6; C₅Me₅, 7; C₉H₇, 8) show the type-A binding mode (see text), while complexes [(η⁶-C₆Me₆)Ru(L^ph)Cl]PF₆3 and [(η⁵-C₅Me₅)Rh(L^ph)Cl]PF₆4 show the type-B binding mode (see text). These differences reflect the more electron-rich character of the [(η⁶-C₆Me₆)Ru(μ-Cl)Cl]₂ and [(η⁵-C₅Me₅)Rh(μ-Cl)Cl]₂ complexes compared to the other starting precursor complexes. Binding modes of the ligand L^ph are determined by ¹H NMR spectroscopy, single-crystal X-ray analysis as well as evidence obtained from the solid-state structures and corroborated by density functional theory calculations. From the systems studied here, it is concluded that the electron density on the central metal atom of these complexes plays an important role in deciding the ligand binding sites.