A method for the reaction of an isatin and cyclopropenone compound at low catalytic amount. In the presence of an amine compound and phosphite, the isatin and cyclopropenone are reacted in an organic solvent using a silicon amino rare earth compound as a catalyst to synthesize pyrano[2,3-b]indol-2-one compounds. In the reaction above, the amount of catalyst is few, and noble metal is not needed for catalysis. The present method can achieve preparation of the pyrano[2,3]indol-2-one compound efficiently and simply.

Disclosed herein are a chromium compound represented by Formula 1a or 1b and a catalyst system including the same, exhibiting superior catalytic activity in an olefin trimerization reaction:
[{CH.sub.3(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CO.sub.2}.sub.2Cr(OH)][Formula 1a]
[{CH.sub.3CH.sub.2CH(CH.sub.2CH.sub.3)CO.sub.2}.sub.2Cr(OH)].[Formula 1b]

The present invention relates to an oligomerization catalyst a transition metal or transition metal precursor, a halogen-substituted organic ligand, and a heteroatom ligand, and to a method for selectively preparing 1-hexene or 1-octene from ethylene using the catalyst.

The present invention provides a process for preparing a water splitting catalyst containing [Mn.sub.4CaO.sub.4] core structure and use thereof. The present invention provides clusters containing [Mn.sub.4CaO.sub.4] core structure by a chemical synthesis using inexpensive metal ions (Mn.sup.2+, Ca.sup.2+ ions), simple carboxyl ligands and a permanganate, performed single crystal X-ray diffraction on their space structure, and characterized their physical and chemical properties with electron spectrum, electrochemical and electron paramagnetic resonance technologies and the like. These compounds can catalyze water splitting in the presence of oxidant to release oxygen and can also catalyze water splitting on the surface of an electrode to release electrons onto the surface of the electrode to form a current.

Disclosed are processes and intermediates for the preparation of compound (X), which is currently being investigated for the treatment of prostate cancer.

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Disclosed are a novel catalyst system which is a catalyst system for selectively oligomerizing olefin including ethylene and may trimerize and tetramerize olefin, different from the catalyst system for olefin oligomerization reported until now, and a method for preparing an olefin oligomer using same. The present invention provides a catalyst system for olefin oligomerization, including a ligand compound represented by Formula 1; a chromium compound; and a metal alkyl compound, and a method for preparing an olefin oligomer using same.

The present invention relates to a catalyst system comprising a transition metal compound on a solid carrier which is a surface-reacted calcium carbonate. The invention further relates to a method for manufacturing said catalyst system and to its use in heterogeneous catalysis.

A 4,4-divinylazoarylene-bridged diruthenium complex with a general formula [{Ru(CO)(L-?.sup.2[N,S].sup.?)(P.sup.iPr.sub.3).sub.2}.sub.2(?{CH?CHC.sub.6H.sub.2(.sup.iPr).sub.2-2,6}.sub.2N?N-4,4)], its synthesis, and its use as an catalyst in inorganic processes.

A 4,4-divinylazoarylene-bridged diruthenium complex bearing two Ru(CO)Cl(P.sup.iPr.sub.3).sub.2 moieties, its synthesis, and its use as an catalyst in organic processes.

A 4,4-divinylazobenzene-bridged diruthenium complex bearing two Ru(Co)Cl(P.sup.iPr.sub.3).sub.2 moieties, its synthesis, and its use as an catalyst in organic processes.