Heteroatom Chemistry最新文献

Condensation of 2,3-dichloropyrazine with 2-aminobenzenetellurole and 2-amino-5-methylbenzenetellurole, generated in situ by reduction of the corresponding ditellurides, resulted in the formation of novel 10H-pyrazino[2,3-b][1,4]benzotellurazine and its 7-methyl derivative. The products were purified via their well-crystallized 5,5-dibromo derivatives. X-ray crystallographic analysis of the title compound indicates that it has a pronounced V-shape and forms hydrogen-bonded dimers. Te, N-containing heterocycles have the potential of offering access to supramolecular assemblies.

New epoxides, derivatives of pyridine, 2,2′-bipyridine, and 1,10-phenanthroline, were synthesized from the respective α-methylazaarenes. The obtained racemic 2-oxiranyl-azaarenes along with styrene oxide and trans-stilbene oxide were submitted to the ring opening with chiral primary amines as a chiral auxiliary. The most effective reaction was run in the presence of Sc(OTf)₃/diisopropylethylamine for 7 days at 80°C, affording a good yield of the amino alcohols. Except for styrene oxide which gave both α- and β-amino alcohols, the reactions led regioselectively to the corresponding diastereomeric β-amino alcohols. The resulting diastereomers were separated, and the configurations of their stereogenic centers were established. The obtained enantiomerically pure 2-pyridinyl- and 6-(2,2′-bipyridinyl)-β-amino alcohols were tentatively tested as chiral ligands in the zinc-catalyzed aldol reaction.

1,2,4-Triazine and 1,2,5-oxadiazine derivatives 2–12 were obtained from treated 1,3-oxazolone (1) with phenyl hydrazine or hydroxylamine hydrochloride. Chlorotriazine derivative 3 undergoing condensation reactions with different reagents produced new fused tetrazolo-triazine and triazino-quinazolinone derivatives. 1,2,5-Oxadiazine has been used as a synthon for the fused pyrazolo-oxadiazine derivative. The constitution of the prepared compounds was built up based on microanalytical and spectral data. Some of the new compounds were assessed for their antimicrobial activity.

This work reports an efficient method for the oxidation reaction of aliphatic, aromatic allylic, and benzylic alcohols into aldehydes catalyzed by the cyclopentadienyl ruthenium(II) complex (RuCpCl(PPh₃)₂) with bubbled O₂. Through further optimizing controlled studies, the tendency order of oxidation reactivity was determined as follows: benzylic alcohols > aromatic allylic alcohols >> aliphatic alcohols. In addition, this method has several advantages, including a small amount of catalyst (0.5 mol%) and selective application of high discrimination activity of aliphatic, aromatic allylic, and benzylic alcohols.

Structure and bonding of hybrid group 13/14 pyramidal molecules ClE[$$R₄] (E = B–Ga, E′ = C–Ge, R = SiMe₃, SiMe^tBu₂) were studied by DFT calculations. Six pyramidal structures are suggested for their potential synthetic realization.

A new domino reaction between thioaurones and malononitrile has been reported. This reaction allows efficient access to benzothiophene-fused pyran derivatives in good yields under mild reaction conditions. The substrate scope is broad; a series of benzothiophene-fused pyran derivatives have been synthesized.

The host-guest complexation of six amine boranes (R₃NBH₃) by the macrocyclic host molecule cucurbit[7]uril (CB[7]) in aqueous solution has been investigated using ¹H and ¹¹B NMR spectroscopy. The limiting complexation-induced ¹H and ¹¹B chemical shift changes indicate that the amine boranes are included in the hydrophobic cavity of the host molecule. The host-guest stability constants for neutral { R₃NBH₃∙CB[7] } complexes (in the range of 10⁵-10⁷M^-1) have been determined by ¹H NMR competition experiments and are compared with the corresponding values for the isoelectronic/isostructural { R₃NCH₃∙CB[7] }⁺ complexes. Ammonia borane (H₃NBH₃) does not form a host-guest complex with CB[7]. The trends in the host-guest stability constant with the guest molar volume are examined, and the stability is ascribed to the hydrophobic effect (packing coefficient) and quadrupole-dipole interactions.

Phosphole P(V) derivatives are interesting building blocks for various applications from ligand synthesis to material sciences. We herein describe the preparation and characterisation of new 2,4-disubstituted oxo-, thiooxo-, and selenooxophospholes. The nature of the substituents on the phosphole ring determines the reactivity of these compounds towards homodimerization reactions. Aryl and trimethylsilyl substituted oxophospholes undergo selective [4+2] dimerization, whereas, for thiooxo- and selenooxophospholes, light-induced, selective [2+2] head-to-head dimerization occurs in the case of aryl substituents. DFT calculations provide some insights on these differences in reactivity.

Methylthioanilines, a series of sulfur-nitrogen donor ligands substituted with OCH₃, CH₃, Cl, and Br, and their copper(II) complexes have been synthesized and characterized by ¹H and ¹³C NMR, elemental analysis, FTIR, UV-Vis and EPR spectra, molar conductance, and magnetic susceptibility measurements. The NMR spectra of the ligands revealed that the para/ortho protons and para carbon were sensitive to the electronic effect of substituents. The CHNS analysis presented CuLCl₂ (L = OCH₃, CH₃, Cl) and CuL₂Cl₂ (L = Br) stoichiometries for the copper complexes. FTIR spectra showed that the bidentate ligands were coordinated to the copper ion through their nitrogen and sulfur atoms. The electronic spectra have suggested square planar and octahedral geometries for these complexes. The EPR spectra demonstrated that the solid state copper(II) complexes possess $$ orbital ground state and g_∥ > g_⊥ > 2.0023 in a tetragonal environment. The compounds were evaluated for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, and C. albicans. The copper complexes showed higher activity than the parent ligands against S. aureus and B. subtilis; the electron-donating OCH₃ and CH₃ derivatives were more active than the withdrawing Br- and Cl-substituted compounds.

To understand the stability, chelation behaviour, and biological activity of 4-Formylpyridinethiosemicarbazone (H4FPT), it is important to recognize its interactive geometry. Hence, computational studies on geometrically optimized structures of thione and thiol forms of H4FPT were performed. Binary metal complexes of the ligand, H4FPT (L) with the Ni(II) and Cu(II) metal ions (M), were synthesized and characterized by various spectroanalytical techniques as elemental analysis, molar conductance, magnetic susceptibility measurements, LC-MS, TGA, IR, UV-Visible, ESR, and powder XRD. Elemental analysis, LC-MS, and TGA studies indicate 1:2 (ML₂) composition for mononuclear Ni(II) complex and 1:1 (ML) composition for dinuclear Cu(II) complex. Electronic absorption titrations, fluorescence quenching studies, and viscosity measurements suggest intercalative mode of binding of the complexes with calf thymus DNA (CT-DNA). These complexes also promote hydrolytic cleavage of plasmid pBR322. The ligand (H4FPT) and its complexes showed moderate-to-good activity against Gram-positive and Gram-negative bacterial strains. The DPPH radical scavenging studies showed antioxidant nature of both complexes.