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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 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.

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.

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).

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.

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.

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.

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.

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 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.

A coherent green fluorescence is obtained by butylation at the 2-position panchromatic 2,3-diaryl-5,8-diarylquinoxalines to produce the corresponding 2-butyl-2,3-diaryl-5,8-diaryl-1H-quinoxalines. 2-butylation converted one imine unit of the pyrazine ring to an amine group, which has changed the electron donor and acceptor functions to produce a coherent green fluorescence.

The synthesis of new classes of thieno[3,4-b]pyrazines containing electron-donating and electron-withdrawing groups from 2,3-dibromo- and 2,3-di(bromomethyl)thieno[3,4-b]pyrazines is reported. The findings revealed that the thieno[3,4-b]pyrazines functionalized with electron-withdrawing groups could be used as potential building blocks for the generation of new low band gap materials.

A simple synthesis of 5-dialkylamino-6-aryl-(2H)-pyridazin-3-one from 5,6-dichloropyridazinone is described. The synthesis involves a palladium-catalyzed Suzuki-Miyaura cross coupling of 6-chloro-5-dialkylaminopyridazinone with various arylboronic acids as the key transformation.

The assembly of bis-18,18'-desmethyl ritterazine N, originally found in the lipophilic extract of the tunicate Ritterella tokioka which induce apoptosis in apoptosis-resistant malignant cells, in enantiomerically pure form and its activity in the NCI 60 cell panel is described. The synthetic alkaloid, lacking only two of the 52 carbon atoms of the natural product, shows selective activity in the NIH 60 cell panel.

The twelve step biomimetic synthesis and characterization of malbrancheamide and malbrancheamide B is reported. The synthesis involved an intramolecular Diels-Alder reaction of a 5-hydroxypyrazin-2(1H)-one to construct the bicyclo[2.2.2]diazaoctane core.

The development of a novel and convenient orthogonal method for the synthesis of asymmetrically tri- and tetrasubstituted pyrazines starting from para-methoxybenzyl-protected 3,5-dichloro-2(1H)-pyrazinones is demonstrated. The key step in the sequence involves mild, one-step iodine-catalyzed methylation with concomitant aromatization of the generated thiopyrazinone.

A comprehensive study of the reactivity of the C-B bond in Suzuki-Miyaura palladium-catalyzed cross-couplings with aryl/heteroaryl halides is described. The reaction involves the facile conversion of substituted 3-methoxypyridazines into the corresponding pyridazin-3(2H)-ones with good functional group tolerance.

Triptycenyl o-quinone is used for synthesizing a family of shape-persistent dendrimers and macrocycles. These shape-persistent ligands can be used for developing robust coordination frameworks with large free volume.

The preparation of tetrahydropyrazines, dihydropyrazines, pyrazines, piperazinones, and quinoxalines by 1,4-addition of 1,2-diamines to 1,2-diaza-1,3-butadienes bearing carboxylate, carboxylate, carboxamide or phosphorylated groups at the terminal carbon and subsequent internal heterocyclization is described. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-diamines has produced pyrazines.

A series of 12 bridging ligands was prepared and these ligands include a central linker appended to two 1,8-naphthyrid-2-yl or two 1,10-phenanthrolin-2 yl units. Examination of the electronic absorption spectra of the bridging ligands shows the strongest correlation between pairs of ligands having the same central linker.

The dye-sensitized photooxygenation of furanosyl furans easily affords C- or O-glycosides with cis-alpha,beta-unsaturated 1,4-dioxo aglycones. The reaction, performed on a ribofuranosyl furan, provides a useful new entry to a novel pyridazine C-nucleoside that can be achieved through a simple on-pot procedure.

Acrolein is hydrogenated in the presence of various aldehyde partners with Rh(COD)2OTf as pre-catalyst to explore the applicability of catalytic hydrogenation-aldolization methodology vis-a-vis aldehyde enolate generation. The results revealed that catalytic enal hydrogenation represents a viable method for the reductive generation of metalloaldehyde enolates.