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Benzalaminoacetals have led to 2-benzylpyrazines after refluxing with trifluoroacetic acid instead of the expected isoquinolines. This reaction has represented a useful way for preparing a variety of 2-benzylpyrazines from the corresponding benzaldehydes.

The treatment of the 90 degree angular precursor trans-[Ru[Cl.sub.2][(dmso-S).sub.4]] with an equivalent amount of the linear and rigid pyrazine (pyz) linker has produced the molecular triangle [[{trans,cis-Ru[Cl.sub.2][(dmso-S).sub.2]([mu]-pyz)}.sub.3]] instead of the molecular squares. The results have shown that the entropically favored molecular triangles are preferred over the expected molecular squares with metal corner fragments that have favored [N.sub.pyz]-M-[N.sub.pyz] angles narrower than 90 degrees due to the presence of ancillary ligands.

A general synthetic route is developed for the resonance-stabilized pyrazine-bridged bisdithiazolyl framework, involving the reductive deprotection of 2,6-diaminopyrazine-bisthiocyanate and cyclization with thionyl chloride. Variable-temperature single-crystal conductivity measurements have shown that the conductivity is activated at room temperature.

The syntheses, crystal structures, and magnetic susceptibilities of a family of copper pyrazine (pz)-based antiferromagnets with moderate in-plane magnetic exchange is reported. The compounds are well described by the two-dimensional Heisenberg model over most of the temperature range but undergo transition to an ordered state at low temperature.

The density functional theory (DFT) framework is used to study the main features of double group transfer reactions. The results have shown that a wide range of structure-types and processes including type II-dyotropic reactions and the Meerwein-Ponndorf-Verley reduction have taken place through highly synchronous in-plane aromatic transition structures, where the orbital topology is equivalent to that which corresponds to a [D.sub.26]-symmetric aromatic molecule such as pyrazine.

The preparation of the symmetrical heptacyclic core of the spiro 6-6-5-5 ritterazines is reported. It is expected that the key Diels-Alder/Wittig/diene cyclozirconation approach illustrated, supported by ZINDO calculations, would be a general strategy for the stereocontrolled construction of polycarbacyclic target structures.

A series of pyrazine (pz) complexes containing cis-(NH3)(sub 2)Pt(super II), (tmeda)Pt(super II), and trans-(NH3)(sub 2)Pt(super II) entities are synthesized and characterized by X-ray crystallography and/or (super 1)H NMR spectroscopy. The formation of the cyclic tetramer [Pt(super II)](sub 4) complex conforms to expectations of the molecular library approach, which predicts a molecular box when two ditopic building blocks with 90 degree and 180 degree angles, respectively, are combined.

The study of the electrochemical and spectroscopic properties of the pi-conjugated ligand tetra-2-pyridyl-1, 4-pyrazine (tppz) as well the mixed ligand complexes with terpyridine end caps provides a better characterization of the series of multimetallic oligomers of ruthenium (Ru). The results show that these compounds can be excellent wire materials, as they yield low HOMO-LUMO gaps, high delocalization, and the onset of quasi-bond features.

Representative polyfunctional tetrahydropyrido[3,4-b]pyrazine scaffolds are synthesized very readily by a one-pot annelation reaction of pentafluoropyridine with appropriate diamines. The trifluorinated pyridopyrazine products react sequentially with various nucleophiles to give polysubstituted tetrahydropyridopyrazines, demonstrating the potential of the polyfluorinated ring fused pyridine system as a scaffold for the synthesis of polysubstituted pyridopyrazine derivatives.

The enthalpy of binding of 2-methoxy-3-isobutylpyrazine (IBMP) to the mouse major urinary protein (MUP) is examined using a combination of isothermal titration calorimetry (ITC), NMR, X-ray crystallography, all-atom molecular dynamics simulations, and site-directed mutagenesis. The characteristic signature of hydrophobic association in solution depends on the degree of solvation of the binding pocket and the architecture of this pocket is as important as hydrophobicity in determining the relative contribution of enthalpic versus entropic effects in biomolecular associations.

Two isolated pyrazine alkaloids from Botryllus leachi, botryllazines A and B exhibit cytotoxicity against human tumor cells. Regioselective metalation of pyrazines and cross-coupling reactions provide an easy access to botryllazines A and B and to an isomer of botryllazine A with good yields from chloropyrazine.

A general and selective methods for partial reduction of pyridine, pyrimidine, and pyrazine rings of various heteroaromatic compounds with bridgehead nitrogen via Birch reduction motif is reported. This method could serve as a new and effective tool for quick and easy access toward various partially reduced fused heterocyclic compounds.

The synthesis and chemical reactivity of pyridazinedione-based enediynes are presented. The single-crystal X-ray structures showed similar c,d distances (distance between the acetylenic carbons undergoing covalent connection in Bergman cyclization).

Some evidence for the directing effect of the 2-pyridylsilyl groups in Ru-catalyzed intermolecular Pauson-Khand-type reaction (PKR) is provided. Most importantly, the study succeeded in isolating several monometallic Ru complexes relevant to the catalytic reaction.

The electrochemical, spectroscopic, and electroluminescent properties of a family of diimine complexes of Ru featuring various aliphatic side chains as well as a more extended pi-conjugated system are investigated. The incorporation of di-tert-butyl side chains on the dipyridyl ligand is found to be the most beneficial substitution in terms of reducing self-quenching of luminescence.

Quasielastic neutron scattering is used to probe the solid-state ligand dynamics in the coordination polymer Mn [N (CN)(sub 2)](sub 2)(pyz) {pyz = pyrazine} which has double-interpenetrating 3D lattices. The pyrazine ligand is seen to liberate in a deep potential in the low temperature monoclinic phase.

The study describes a novel multi-component synthesis of highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives. The isocyanide-based three-component reaction gives very high yield of the derivatives at ambient temperature.

A volatile route is developed for symmetrical and unsymmetrical pyrazines. The Swern oxidation of the aminodiols is carried out without the protection of the basic amines, showing that the amino diketones are not isolated, but are condensed directly with hydroxylamine to give the substituted pyrazines.

Two new magnetic 3D NaCl-like networks were synthesized in which the metal ions are linked by pyz into (4, 4) sheets and further linked by a [[mu].sub.1,3]-nitrito group. The magnetic investigation reveals that the [[mu].sub.1,3]-nitrite bridge could transmit antiferromagnetic interaction in the case of [Co.sup.2+].

A report on the one-pot synthesis of new 9-alkyl-6-chloropyrido[3,2-e]-[1,2,4] triazolo[4,3-a]pyrazines, which was obtained from 2,3-dichloropyrido[2,3-b]pyrazine in a single step, is presented. The key step was the regioselective nucleophilic aromatic substitution that gave rise to unique isomers before ring closure.

The article explains various mechanisms that are involved in the catalysis and inhibition of nicotinamidase/pyrazinamidase (PncA) from Mycobacterium tuberculosis. Pyrazinecarbonitrile is shown to be one compound that acts as an irreversible inactivator of PcnA.

Cycloparaphenylenes and nitrogen analogues formed from the building blocks pyridinyl, pyrazinyl, pyridazinyl and pyrimidinyl are investigated. Nitrogen substitution has reduced the o,o' steric interactions between neighboring rings and nanohoops pyrazinyl and pyrimidinyl have ribbon-like structure with dihedral angles between neighboring rings near zero.

A supramolecular three-component double-porphyrin tweezer (PT) is prepared by using heteroleptic complex formation along the HETTAP method. The higher stability of PT-(DABCO)(py) is the result of charge transfer from DABCO to the vacant [pi]* orbital of pyrazine across the porphyrin plane.

Asymmetric scandium(III)-catalyzed rearrangement of 3-allyloxyflavones is used for preparing chiral, nonracemic 3,4-chromanediones in high enantioselectivities. The initial studies of the mechanism have supported an intramolecular arrangement pathway that has proceeded via benzopyrylium intermediate.

The mechanism study of C-F reductive elimination from a transition metal complex and the evaluation of C-F bond formation from three Pd(IV) fluoride complexes are described. The ancillary pyridyl-sulfonamide ligand has played a main role for C-F reductive elimination in which an oxygen atom of the sulfonyl group has coordinated to Pd.

Photolysis of triazolo[1,5-b]pyridazine isolated in Ar matrix has generated diazomethylpyridazines and diazopentenynes as detected by IR spectroscopy. Three possible mechanisms of ring-contraction in arylnitrenes are identified by ring-opening to dienylnitrenes, concerted ring-contraction and by spiroazirenes.

A novel [PPh.sub.3]-catalyzed (4+n) annulation of 2-(acetoxymethyl)buta-2,3-dienoates with 1,n-bisnucleophiles (n = 1, 2) is developed for providing a facile synthetic method for cyclopentene and 1,2,3,6-tetrahydropyridazine derivatives. The acetate group of 2-(acetoxymethyl)buta-2,3-dienoate is very important for the formation of 1,4-biselectrophilic intermediate and deuterium studies have shown that the reaction pathway has involved a proton-transfer process.

Several experimental and first-principles studies are conducted to explain the 1D to 3D magnetic transformation taking place in the copper pyrazine dinitrate S = 1/2 antiferromagnetic crystal. The magnetic susceptibility and heat capacity curves of the crystal are shown to remain unchanged with the spin and magnetic chains.

The article explains synthesis, as well as the characterization of a series of condensed oligopyrazine analogues of acenes, the pyrazinacenes. These compounds are shown to be widely used in the organic thin film transistors.

The synthesis, crystallization, and solid-state NMR dynamics of molecular structures composed of polar pyridine and pyridazine groups as well as their corresponding N-oxides, proposed to emulate the structure and function of macroscopic compasses are described. The preparation and crystal structure of pyridine-[d.sub.2] and pyridazine-[d.sub.10], one labeled with deuteria in the pyridine rotator and the other fully deuterated in the two trityl groups in the stator are also described.

Allylic esters bearing the (2-pyridine)C[O.sub.2]-, (2-pyrazine)C[O.sub.2]-, [(EtO).sub.2]P[O.sub.2]-, [C.sub.6][F.sub.5]C[O.sub.2]-, o-([Ph.sub.2]P)[C.sub.6][H.sub.4]C[O.sub.2]-, MeOC[O.sub.2]-, or AcO- group were examined to establish allylic substitution of secondary allylic alcohol derivatives with alkynyl copper reagents. Mg[Br.sub.2] (3 equiv) promoted the reaction to produce the anti [S.sub.N]2' product in 93% yield with 94% regioselectivity and 99% chirality transfer.

A study was conducted to examine drug-like inhibitors of tau assembly using quantitative high-throughput screening (qHTS) of [approximately]292000 compounds. Findings revealed classes of inhibitors, including novel aminothienopyridazines (ATPZs).

The nanoporous metal-organic framework [Fe(pz)Ni[(CN).sub.4]], (pz = pyrazine) which exhibit hysteretic spin-crossover at ambient conditions and is robust to the adsorption and desorption of a wide range of small molecular guests, both gases ([N.sub.2], [O.sub.2], C[O.sub.2]) and vapors (methanol, ethanol, acetone, acetonitrile, and toluene) is described. Guest desorption followed by adsorption, and vice versa, could be used to switch between spin states in the bistable temperature region to add a guest-dependent memory effect to this system.

The ultrafast photoelectron imaging technique was used to perform ultrafast internal conversion of [S.sub.2] to [S.sub.1] of pyrazine through a conical intersection of the potential energy surfaces. The two-dimensional time-energy map of the photoelectron angular anisotropy revealed a clear signature of the internal conversion (the color change of green-orange-green in the horizontal direction).

The reaction of Cr[([C.sub.6][H.sub.6]).sub.2] and 1,2,4,5-tetracyanopyrazine (TCNP) has formed [Cr[([C.sub.6][H.sub.6]).sub.2][TCNP], and TCNP is reduced and has formed the eclipsed [pi]- [[TCNP].sub.2.sup.2-] dimer. [[TCNP].sub.2.sup.2-] is described by an atoms-in-molecules analysis as having a 2[e.sup.-]/8c C-C bond that has involved the four C atoms from each six-member ring.

The coordination-driven self-assembly of ortho-linked oxacalix[2]benzene[2]pyrazine as well as oxacalix[2]arene[2]pyrazene with a silver cation has helped in the formation of a discrete molecular cage and a one-dimensional chain of coordination cages. The void of the metal-containing cage is occupied by a methyl group of an acetonitrile bonded to a neighboring cage in the solid state and one benzene ring is present in the void of each one-dimensional chain of coordination cage complex.

o-C-H silylation of arylboronic acids is achieved by using 2-pyrazol-5-ylaniline as an ortho-directing agent, which is temporarily attached to the boronyl group via Ru-catalyzed silylation with hydrosilanes. The silylated products are used in Suzuki-Miyaura coupling, which is followed either by iodination with ICl or by Tamao oxidation to furnish iodine- or hydroxyl-substituted biaryls.

The synthesis, and structural and magnetic characterization of three [Cu.sup.2+]-containing coordination polymers, [Cu(H[F.sub.2])[(pyrazine).sub.2]]Sb[F.sub.6], [[Cu.sub.2]F(HF)(H[F.sub.2])[(pyrazine).sub.4]][(Sb[F.sub.6]).sub.2], and [CuAg([H.sub.3][F.sub.4])[(pyrazine).sub.5]][(Sb[F.sub.6]).sub.2] are presented. The polymers are found to crystallize in either tetragonal or orthorhombic space groups, have structures consisting of 2D square layers of [[M[(pyz).sub.2]].sup.n+] that are linked in the third dimension by either H[F.sub.2.sup.-] or [H.sub.3][F.sub.4.sup.-] and the variations observed in magnetic behaviors are driven by differences in the H***F hydrogen-bonding motifs.

A cobalt-catalyzed cross-coupling of aryl halides with 2-chloropyrimidines or 2-chloropyrazines is described. The main step in this method is the formation of aromatic organozinc reagents and their coupling with 2-chlorodiazines using the same cobalt halide as catalyst and Zn duster under mild conditions.