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A theoretical study of the reactivity of pyrazaboles with amines and pyrazoles has been carried out at DFT level in gas phase, toluene and water media. The reaction with amines yields two molecules of pyrazolylboranes, while the reaction with pyrazoles allows to understand the interchange of such molecules in the pyrazaboles. The reaction of three pyrazaboles with two amines [N[H.sub.3] and NM[e.sub.3]] and pyrazole itself has been considered. The [S.sub.N]2 and [S.sub.N]1 mechanisms have been analyzed. The [S.sub.N]2 reaction is more favorable than the [S.sub.N]1 in the absence or presence of amines. Keywords: pyrazaboles, pyrazolylboranes, [S.sub.N]2, [S.sub.N]1, dative bonds Nous avons realise une etude theorique de la reactivite des pyrazaboles avec les amines et les pyrazoles au niveau de la theorie de la fonctionnelle de la densite (DFT) en phase gazeuse, dans le toluene et en milieu aqueux. La reaction avec les amines mene a la formation de deux molecules de pyrazolylboranes, tandis que la reaction avec les pyrazoles permet de comprendre l'echange de ces molecules dans les pyrazaboles. Nous avons examine la reaction de trois pyrazaboles avec deux amines [N[H.sub.3] et NM[e.sub.3]] et le pyrazole comme tel. Nous avons analyse les mecanismes [S.sub.N]2 et [S.sub.N]1. La reaction [S.sub.N]2 est plus favorable que la reaction [S.sub.N]1, en l'absence comme en presence d'amines. [Traduit par la Redaction] Mots-cles : pyrazaboles, pyrazolylboranes, [S.sub.N]2, [S.sub.N]1, liaisons bipolaires, 1. Introduction At the intersection of the fields of boron, heterocyclic, and coordination chemistry, there are two topics, both discovered by Trofimenko in the 1966-1967, which have been a success [...]

An efficient approach for the synthesis of N-acetyl- and N-aroyl-2-pyrazlines by intramolecular Michael addition of [alpha],[beta]-unsaturated hydrazones is reported. The strategy can be applied to obtain substituted azaproline derivatives in a diastereoselective route.

The representative of P,P,P-trichloroylides-5-methyl-2-phenyl-4-(trichlorophosphoranylidene)2,4-dihydro-3H-pyrazol-3-one was synthesized and characterized. Some chemical properties were studied and compared with one of P,P,P-trichloroylides-5-methyl-2-phenyl-4-(trichlorophosphoranylidene)2,4-dihydro-3H-pyrazol-3-one.

Second-order degenerate perturbation theory, in conjunction with the group homomorphism method for describing a similarity transformation, are used to characterize the subspace of two-state conical intersections contained in the branching space of a three-state conical intersection. It is shown by explicit calculation, using the lowest three-state conical intersection of (CH)3N2, that a second-order treatment yields highly accurate absolute energies, even as significant distances from the references point of three-state intersection.

The electron affinity (EA), photoelectron spectrum and the spectral analysis of 1-pyrazolide are presented. The thermodynamic properties of the pyrazole system, as well as the electronic structure of the corresponding radicals are discussed.

Several elegant methods for the regioselective synthesis of unsymmetrically substituted 1-arylpyrazoles that are reported in the literature are discussed. The 1-phenylpyrazole motif is present in several drug candidates for treatment of various diseases like cyclooxygenase-2 inhibitors, II-1 synthesis inhibitors and protein kinase inhibitors.

A novel one-step synthesis route to fully substituted pyrazol-4-ols is reported. This simple yet nonobvious method for the construction of pyrazol-4-ols by the condensation-fragmentation-cyclization-extrusion reactions of thietanones with 1,2,4,5-tetrazines is reported.

A highly efficient one-pot conversion of [beta]-aminocrotononitrile to secondary enaminonitriles including chiral ones is described. In contrast to [beta]-aminocrotononitrile, some of these N-substituted [beta]-enaminonitriles on reacting with acid chlorides show a unique preference for C-terminal selection allowing preparation of pyrazoles without separation of regioisomers. In addition, use of secondary enaminonitriles also provided access to pyrazoles that are not obtainable with primary enaminonitriles owing to an exclusive preference for N-terminal selection. Key words: [beta]-aminocrotononitrile, N-substituted enaminonitriles, regioselective, pyrazoles. Resume : On decrit une methode unipot tres efficace de conversion du [beta]-aminocrotononitrile en enaminonitriles secondaires, y compris ceux de nature chirale. Contrairement a ce qui est observe avec le [beta]-aminocrotononitrile, certains de ces [beta]-enaminonitriles N-substitues reagissent avec les chlorures d'acides avec une preference unique pour la position C-terminale, ce qui permet de preparer des pyrazoles sans avoir a separer les regioisomeres. De plus, l'utilisation d'enaminonitriles secondaires permet aussi d'acceder a des pyrazoles qui ne peuvent pas etre obtenus a partir de l'enaminonitrile primaire en raison de la preference exclusive pour la selection N-terminale. Mots cles : [beta]-aminocrotononitrile,enaminonitriles N-substitues, regioselective, pyrazoles.

A systematic study of the synthesis of the 5,7-diaryl-4-oxo-pyrazolo [3,4-d]pyrimidin-6-thiones (3), 2-phenyl5,7-bis(2'-methylphenyl)-4-oxo-pyrazolo[3,4-d]pyrimidin-6-thiones (4b), 2(3H)-3-phenyl-5,7-diaryl-4-oxo-pyrazolo[3,4d]pyrimidin-6-thiones (5), 5,7-diaryl-4-oxo-isoxazolo[5,4-d]pyrimidin-6-thiones (7), 3,5,7-triaryl-2,3-dihydro-4-oxoisoxazalo [5,4-d]pyrimidin-6-thiones (8), 2-amino-6,8-diaryl-5-oxo-pyrimido[4,5-d]pyrimidin-7-thiones (9), 3,4-dihydro-2-amino-4-phenyl-6,8-diaryl-5-oxo-pyrimido [4,5-d]pyrimidin-7-thiones (10), 3-cyano-6,8-diaryl-2,5-dioxo-pyrido[2,3d]pyrimidin-7-thiones (11) from the condensation products 1 and 2, derived from 1,3-diaryl-2-thiobarbituric acids is described. Key words: synthesis, fused, pyrazole, isoxazole, pyrimidines. Resume : On decrit une etude systematique de la synthese des 5,7-diaryl-4-oxo-pyrazolo [3,4-d]pyrimidin-6-thiones (3), 2-phenyl-5,7-bis(2'-methylphenyl)-4-oxo-pyrazolo[3,4-d]pyrimidin-6-thiones (4b), 2(3H)-3-phenyl-5,7-diaryl-4-oxopyrazolo[3,4-d]pyrimidin-6-thiones (5), 5,7-diaryl-4-oxo-isoxazolo[5,4-d]pyrimidin-6-thiones (7), 3,5,7-triaryl-2,3dihydro-4-oxo-isoxazolo[5,4-d]pyrimidin-6-thiones (8), 2-amino-6,8-diaryl-5-oxo-pyrimido[4,5-d]pyrimidin-7-thiones (9), 3-4-dihydro-2-amino-4-phenyl-6,8-diaryl-5-oxo-pyrimid [4,5-d]pyrimidin-7-thiones (10) et 3-cyano-6,8-diaryl-2,5-dioxopyrido [2,3-d]pyrimidin-7-thiones (11) a partir des produits de condensation 1 et 2 obtenus a partir des acides 1,3-diaryl-2-thiobarbituriques. Mots cles : synthese, condense, pyrazole, isoxazole, pyrimides.

The absorption and emission spectra for a series of substituted 1,3-diphenyl-5-pyrene-2-yl-4,5-dihydro-1H-pyrazole (DPPyP) molecules are computed by TDDFT methods. The solvent effect is modeled using the self-consistent reaction field (SCRF) method with Tomasi's polarized continuum model (PCM). The ground-state geometries were optimized by the Hartree-Fock method with the 6-31G basis set (and also with 3-21G * for molecule A) (HF/6-31G), and the lowest singlet excited-state geometries were optimized at the ab initio CIS level with the 6-31G basis set (CIS/6-31G). The calculated results indicate that the TDDFT method can reproduce the experimental values. We consider the effects of different basis sets on the optimization of the ground-state geometries. Specially, some insights on the differences observed for these compounds in changing the substituted donors (H, C[H.sub.3], and N[H.sub.2]) and acceptor group (CN) are given; the results indicate that introduction of the donor groups will lead emission to be red-shifted, while introduction of the acceptor will induce the emission to be blue-shifted, which provides useful information for modulating light-emitting material colors. Key words: absorption and emission, TDDFT, CIS, SCRF-PCM.

An unusual reaction process that produced unexpected heterocyclic systems by a fragmentation-recombination mechanism is described. Evidence for the mechanism of the formation of the dihydropyrazoles is presented for supporting the novel fragmentation-cycloaddition process.

The B3LYP functional is adopted to study a series of possible surface complexes and to obtain information on the adsorption mechanism of pyrazole on silver colloid. The pyrazolide when adsorbed on silver colloidal particles was found to exhibit charge delocalization upon the ring and was also found to transfer half of its negative charge to metal.

A practical and scalable pathway to selective CC[K.sub.1] receptor antagonist is described. The key features in the concise route include a regioselective construction of the pyrazole core through the reaction of an aryl hydrazine and an elaborated acetylenic ketone, a [Tf.sub.2]O/pyridine mediated Z-selective dehydration of an [alpha]-hydroxyester and a stereoselective hydrolysis.

1,3-Dipolar cycloaddition reactions of VDCP-diesters with aromatic diazomethanes generated in situ from the aromatic aldehydes and tosylhydrazine mediated by base produce pyrazole derivatives under mild conditions. A plausible reaction mechanism is proposed based on the control experiments along with the discussion on the regioselectivity.

Catalytic CuI and sparteine have annulated 2-formylpyrroles with o-aminoiodoarenes to produce substituted pyrrolo[1,2-a]quinoxalines and related heterocycles. The reaction has worked for annulation of 2-formylindoles, 2-formylimidazole, 2-formylbenzimidazole and a 3-formylpyrazole.

The cycloaddition of 4-iodosydnones with terminal alkynes has proceeded with good regiocontrol in order to produce 5-iodo pyrazoles. These products have participated in subsequently C-C and C-heteroatom bond forming processes.

A facile and efficient Cu(I)-catalyzed cross-coupling method is described for preparing of N-alkynyl or N-bromoalkenyl heteroarenes from bromoalkynes. The studies have shown that poly(ethylene glycol) 400 (PEG400) has acted as both a Cu(I)-stabilizing ligand as well as a phase transfer solvent.

A short and straightforward synthesis of a series of pyrazolo[1,5-f]phenanthridine derivatives and regioselective synthesis of 1,5-diarylpyrazole intermediates are described. The scope and limitations of the two methodologies are explored to establish the complementariness of the reaction and also establish the environmentally safer porotcols for catalysts used.

A newly developed chelation-assisted palladium-catalyzed cascade bromination/cyanation reaction of 2-arylpyridine and 1-arylpyrazole C- H bonds is reported. The one-pot reaction which utilized [K.sub.3][Fe[(CN).sub.6]] as a safe and nontoxic cyanide source provide aromatic nitriles in moderate to good yields.

The studies related to the scope and limitation of the combined ruthenium-lipase induced dynamic kinetic resolution (DKR) through O-acetylation of racemic heteroaromatic secondary alcohols (1-heteroaryl substituted ethanols) are presented. The results obtained provide better understanding of the mechanistic aspects behind the difference in reactivity of 1-heteroaryl substituted ethanols in comparison to reference substrates.

The efficient Suzuki cross-coupling of pyrazoline nonaflates with organoboron reagents was performed to obtain diverse 3-substituted-2-pyrazolines in excellent yield. The wide scope of the process could be used as a rapid, divergent strategy for the synthesis of elaborated 2-pyrazolines that are not readily available via conventional methods.

The addition of diazomethane and diazoethane to enantiopure (S)-(+)-3-[(methylphenyl)sulfinyl]-5,6-dihydropyran-2-one has produced the corresponding pyrazolines with almost complete [pi]-facial selectivity. The results are improved starting from sulfonyl pyrazolines, which has produced pure 3-oxabicyclo[4.1.0] heptan-2-ones.

A novel, short and convenient synthesis of pyrazolo[1,5-a]quinoxalines from simple quinoxalines is described. The key step in the synthesis involves the reaction of an oxime with acetic anhydride which proceeded under formation of an N-N bond and cleavage of a C-O bond.

An intramolecular 1,3-dipolar cycloaddition method is used for an efficient synthesis of the benzofuropyrazole skeleton. The method could be used to prepare a wide range of pharmaceutically active benzofuropyrazoles by using Pd-catalyzed coupling strategies.

The development of a new efficient strategy for the preparation of 3-alkoxymethyl-pyrazolo[3,4-b]pyridines is reported. The compounds could be manipulated to access 3-alkoxymethyl-pyrazolo[3,4-b]pyridines with a variety of substitution patterns as well as 3-aminomethyl-pyrazolo[3,4-b]pyridines.

The role of viscosity or solvent friction in ionic liquids for an intramolecular Diels-Alder (IMDA) reaction of (E)-1-phenyl-4-[2-(3-methyl-2-butenyloxy)benzylidene]-5-pyrazolone is studied. The results have shown that the solvent microviscosity, rather than the bulk macroscopic viscosity, is the criteria for selecting the ionic liquids as the reaction media.

The use of the fluorinated alcohols trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP) to facilitate the regioselective synthesis of pyrazole is reported. The pyrazoles obtained could be used as synthetic intermediates to prepare fluorinated analogs of tebufenpyrad, a commercial acaricide.

The synthesis of highly substituted isoxazoles, 1-acyl-5-hydroxy-4,5-dihydro-1H-pyrazoles by the electrophilic cyclization of 2-alkyn-1-one O-methyl oximes is reported. The reaction provides selective route to ICI-induced dehydration of a heterocyclic derivative that provides iodinated pyrazoles.

The three-component condensation of 5-aminopyrazoles, aromatic aldehydes, and cyclic 1,3-diketones to selectively obtain three distinct reaction products, pyrazolo[3,4-b]quinolin-5-ones, pyrazolo[5,1-b]quinazolin-8-ones, and pyrazolo[4,3-c]quinolizin-9-ones is presented. The tricyclic heterocycles could give moderate to good isolated yields.

A new simple method for the synthesis of various N-methyl-4-fluoro-5-substituted-1H-pyrazoles in high yield is developed. The selective high-yielding method allows to prepare chromeno[2,3-d]pyrazol-9-one compound as a new class of azaxanthones.

A simple and efficient procedure for the silver(I)-catalyzed formation of pyrazoles from propargyl N-sulfonylhydrazone is reported. The methodology facilitates the efficient and regioselective synthesis of 1,3- and 1,5-disubstituted and 1,3,5-trisubstituted pyrazoles.

The photophysical behavior of 3-pyrazolyl-2-pyrazoline derivative (PZ) is analyzed in micellar solutions of anionic sodium dodecyl sulfate (SDS), cationic cetyl trimethylammonium bromide (CTAB) and nonionic p-tert-octylphenoxy polyoxyethanol micelle by using steady state and time-resolved fluorescence spectroscopy method. The results are interpreted in terms of the model that urea displaces water molecules from the micellar interface and the consequent destabilization has led to the expulsion of the probe molecules from the interfacial region.

An efficient and modular approach for the regiocontrolled preparation of pyrazoles having substituents of all three-carbon atoms is described. The method uses an easily switchable metal-directing group to enable sequential direct lithiation of the 3- and 5-positions of the pyrazole ring.

Azinyl and diazinyl ketone hydrazones are suitable starting materials for ring closure to fused pyrazoles. Quantum chemical calculations reveal that the mechanism of these cyclizations specifically depend on the applied reaction conditions.

An enhanced method to obtain pyrazole with increased regioselectivity by using fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as solvents is reported. The modified method can be applied to synthesize fluorinated analogs of tebufenpyrad with acaricide activity.

A simple and efficient one-pot synthesis of acyclic polyols fused with pyrazolo[1,5-a]pyrimidines and 1,2,4-triazolo[1,5-a]pyrimidine as novel carbohybrids with regioselectivity is reported. The synthesis involved the condensation of 2-C-formyl glycals with 3-aminopyrazoles and 3-amino-1,2,4-triazoles in excellent yields under the microwave irradiation.

Neutral and other acidic called two protocols were developed for the regioselective synthesis of 1,3,5-tri- and 1,3,4,5-tetrasubstituted pyrazoles. The reaction involving interaction between electron-deficient N-arylhydrazones and nitroolefins provides insight into stereochemistry of the key pyrazolidine intermediate and stepwise cycloaddition mechanism.

Sulfides and sulfones, derived from the initial ring-opening of 2-nitrothiophene with pyrrolidine/AgN[O.sub.3] in EtOH, are reacted with diazomethane for the synthesis of heterocycles. Dichotomic behavior has yielded pyrazolines from sulfides and isoxazolines from sulfones.

The chemistry of diazafulvenium methides generated by the thermal xtrusion of sulfur dioxide from 2,2-dioxo-1H, 3H-pyrazolo[1,5-c] [1,3]thiazoles is described. The diazafulvenium methides unsubstituted at C-7 participate in [8pie + 2pie] cycloadditions giving pyrazolo-annulated heterocycles resulting from the addition across the 1,7-position.

An investigation of 1,3-dipolar cycloaddition of trimethylsilyldiazomethane with alpha,beta-unsaturated esters is presented. It is demonstrated that the distribution of 2-pyrazoline products is highly dependent on the relative configuration of the substituents on the 1-pyrazoline intermediate.

A B[H.sub.3] pyridine reduction method was developed for a variety of functionalized N-acylated dihydropyrazoles, which proceed in good to high yield applicable in kilogram scale. The resulting acylpyrazolidine products that arise upon reduction were isolated in good to high yields following exposure to reaction conditions, which were shown to tolerate a variety of different functional groups.

A series of arylpyrazole compounds, which specifically bind the glucocorticoid receptor (GR), selectively modulates GR-regulated biological functions in preadipocyte, preosteoblast, and lung epithelial cell lines. Subtle differences in ligand chemistry can profoundly influence the transcriptional regulatory activity of GR, and that endogenous genes bearing natural glucocortidcoid receptor elements (GREs) are especially sensitive detectors of these differences.

A general protocol for the palladium-mediated Suzuki coupling reaction of pyrazole triflates and aryl boronic acids is developed. The use of additional dppf ligand was determined to increase product yields allowing for the use of a broad range of reaction substrates.