[reaction: see text] A highly practical, general method for catalytic formation of substituted pyridines from a variety of unactivated nitriles and alpha,omega-diynes is given. The reactions which were catalyzed by 5 mol % of dppe/CoCl2-6H2O in the presence of Zn powder (10 mol %) could proceed at rt to approximately 50 degrees C with high functional compatibility and regioselectivity.

[reaction: see text] A 2-(2,6-diisopropylphenyl)iminomethylpyridine (1a)/CoCl(2).6H(2)O/Zn reagent has been developed as an effective instant catalyst for the intra- and intermolecular cyclotrimerization of alkynes to substituted benzenes, making the method extremely practical since the reagent, 1a/CoCl(2).6H(2)O/Zn, is inexpensive and easy to handle and the reaction is less sensitive to moisture and is reasonably general.

An iron species derived from FeCl 2 or FeCl 3 by in situ reduction with zinc powder in the presence of imidazol-2-ylidene or bidentate nitrogen ligand could effectively catalyze intramolecular cycloisomerization of triynes to annulated benzenes. With a 2-iminomethylpyridine ligand, hydrates of FeCl 2 and FeCl 3 as well as their anhydrous ones could be used.

Imidazolium and 4,5-dihydroimidazolium carbene-CuCl complexes effectively catalyzed the substitution reaction of allylic compounds with Grignard reagents in an S N 2 0 -selective fashion. It was noteworthy that the amount of the imidazolium carbene-CuCl complex could be reduced to 0.001 mol% and the catalysis recorded a high TON (10 5 ). Based on the experimental results, the atetype complex(es) such as [(imidazolium carbene)-CuR 2 ] À (MgX) + was postulated as an active species.

A variety of substituted 2,2'-bipyridines were synthesized by a 1,2-bis(diphenylphosphino)-ethane (dppe)/cobalt chloride hexahydrate (CoCl 2 ·6 H 2 O)/zinc-catalyzed [2 + 2 + 2] cycloaddition reaction of diynes and nitriles, with all reactions exhibiting exclusive regioselectivity. Thus, symmetrical and unsymmetrical 1,6-diynes and 2-cyanopyridine reacted in the presence of 5 mol % of dppe, 5 mol % of CoCl 2 ·6 H 2 O and 10 mol % of zinc powder to provide the corresponding 2,2'-bipyridines. Under identical reaction conditions, 1-(2-pyridyl)-1,6-diynes and nitriles reacted smoothly with exclusive regioselectivity to produce 2,2'-bipyridines in good yield. 2,2'-Bipyridines were also obtained by the double [2 + 2 + 2] cycloaddition reaction of 1,6,8,13-tetraynes with nitriles. Similarly, 2,2':6',2''-terpyridines were synthesized from 1-(2-pyridyl)-1,6-diyne and 2-cyanopyridine. The regiochemistry observed can be explained by considering the electronic nature of cobaltacyclopentadiene intermediates and nitriles. A survey of the exclusive regiochemical trend gives reasonable credence to the synthetic potential of the present method.

New electron-transporting materials for organic light-emitting devices (OLEDs) based on trisubstituted benzene with both bipyridine and terpyridine, 1,3-bisbipyridyl-5-terpyridylbenzene (BBTB) and 1-bipyridyl-3,5-bisterpyridylbenzene (BTBB), were developed. Glass transition temperatures of BBTB and BTBB were 93 C and 108 C, respectively, and BTBB was completely amorphous with no melting point. Electron mobilities of BTBB exceeded the order of 10 were reached at voltages of 3.0 V and 4.5 V, respectively. In addition, ionization potentials of BBTB (6.33 eV) and BTBB (6.50 eV) were sufficiently large to confine holes in common emissive layers.

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A NiCl 2 -6H 2 O/Zn reagent with a 2-aryliminomethylpyridine ligand catalyzed cyclization/polymerization of 1,6-diynes mainly to yield the corresponding poly(1,3-butadienylene) compounds, 10 whereas, NiBr 2 -3H 2 O/Zn with use of 3-(2-(2-methoxyethoxy)-ethyl)-1-methyl-1H-imidazol-3-ium bromide as a ligand converted 1,6-diynes to the corresponding annulated 1,3,5,7-cyclooctatetraenes in a biphasic solvent system consisting of toluene and an ionic liquid. 15For homogeneous metal-catalyzed reactions, a bimetallic or bimolecular cooperative mechanism has often been proposed, where a dimerization of the metal species or dimeric interaction of the metal species plays a critical role: 1 Many cases have been postulated in which a bimetallic or bimolecular mechanism is 20 involved as a major course for effective, selective production of the desired compound. Meanwhile, the reverse case has also been reported in which dimerization of the metal species deactivates the catalyst by forming stable, coordinatively saturated, inert complexes and furthers decomposition by disproportionation. In 25 this context, isolating the catalyst to a solid phase from a solution phase by immobilization onto polymeric supports or inorganic materials is a versatile means not only for avoiding the formation of dimeric metal molecules thereby deactivating and decomposing the catalyst but also for increasing the catalyst 30 reactivity and selectivity via a bimetallic or bimolecular mechanism. 2 Herein we propose a new strategy for controling the reactions which proceed through formation of a dimeric metal intermediate: Isolation (or immobilization) of the metal-catalyst 35 into an ionic liquid (IL) 3 phase in an IL/usual organic solvent biphasic system which can separate the catalyst from the employed substrate and maintain a high catalyst concentration in the IL phase throughout the reaction, a situation which might be favorable for reactions via a dimeric metal intermediate and corresponding COTs catalyzed by a (DME)NiBr 2 /Zn [DME = 1,2-dimethoxyethane] reagent in THF-H 2 O, where reaction with a large amount of catalyst loading (20~40 mol%) realized highly selective production of COTs against co-production of [2+2+2] cycloadducts. 6 The results were rationalized by assuming the 55 dimeric mechanism that Wilke suggested.Cyclooctatetraenes (COTs) are of interest as ligands capable of coordinating to various metal atoms and electron transporting components in organic light-emitting devices, and especially as precursors for polyacetylenes in the ring-opening metathesis 60 polymerization (ROMP) reaction. 7 Efforts, therefore, have been made in developing methods for synthesizing COTs. 8 Of the existing methods, the transition metal-catalyzed [2+2+2+2] cycloaddition of alkynes can be considered one of the most attractive and direct. 65During the course of studying the transition metal-catalyzed cycloisomerization of alkynes, 9 we found that a 2-(aryliminomethyl)pyridine/NiCl 2 -6H 2 O/Zn reagent catalyzed cycloaddition of diethyl dipropargylmalo...