Koichiro Oshima

Reactions of alkenylchromium reagents prepared from alkenyl trifluoromethanesulfonates (triflates) with chromium(II) chloride under nickel catalysis

philicities in these complexes, with vanadium in complexes 4 and 5 exhibiting greater electrophilicity. Given the inclination of other 17-electron metal carbonyl complexes to undergo associative ligand displacement reactions, it seems ironic that the incorporation of a pentadienyl ligand, which would be expected to promote associative attack via

Nickel-Catalyzed Carboxylation of Organozinc Reagents with CO2

73 coordination changes, should lead instead to a series of compounds for which much lower rates of substitution are observed and for which the substitutions also take place via dissociative means. Additional kinetic, EPR, and structural studies are under way in attempts to better understand the unexpected behavior of these 17-electron complexes.

Regio- and stereoselective ring opening of epoxy alcohols with organoaluminium compounds leading to 1,2-diols

An efficient nickel catalyst system for the carboxylation of organozinc reagents with CO(2) under very mild conditions has been developed. The catalyst system complements the conventional methods and enables the direct synthesis of various saturated carboxylic acid derivatives from the corresponding alkylzinc reagents and CO(2).

Selective oxidation of a primary hydroxyl in the presence of secondary one

Introduction of alkyl, alkynyl group, or hydride occurs regioselectively at the 3 position of the epoxy alcohols with inversion of the configuration upon treatment with organoaluminium reagents to produce vic-diols.

Triethylborane-induced stereoselective radical addition of perfluoroalkyl iodides to acetylenes

Abstract RuCl 2 (PPh 3 ) 3 -benzene system has been found to be highly effective for the title selective oxidation providing 10-hydroxyundecanal in 89% yield from 1,10-undecanediol.

Cerium catalyzed selective oxidation of secondary alcohols in the presence of primary ones

Abstract Treatment of terminal or internal acetylenes bearing a variety of substituents with perfluoroalkyl iodides in the presence of a catalytic amount of triethylborane provides the corresponding perfluoroalkenes in good to excellent yields. The addition of perfluoroalkyl iodides to olefins is also described.

New synthetic reactions catalyzed by cobalt complexes

The combination of (N42Ce(NO3)6-NaBrO3 or CE(SO4)2·2H2SO4-NaBrO3 has been found to be effective for the title selective oxidation.

Synthesis of 3-Trifluoromethylbenzo[b]furans from Phenols via Direct Ortho Functionalization by Extended Pummerer Reaction

Without suffering from β-elimination, cobalt complexes allow cross-coupling reactions of alkyl halides with Grignard reagents. A combination of a cobalt complex and trimethylsilylmethyl Grignard reagent effects Mizoroki-Heck-type reaction of alkyl halide with styrene, which conventional palladium catalysts have never made possible. Cobalt exhibits intriguing catalytic activities on hydrophosphination and allylzincation of alkynes. Silylmethylcobalt reagent is a powerful tool for the synthesis of highly silylated ethenes.

Aldol reaction of aluminium enolate resulting from 1,4-addition of Me2AlSPh to α,β-unsaturated carbonyl compound. A 1-acylethenyl anion equivalent

A concise and diversity-oriented route to trifluoromethylbenzo[b]furans has been devised. A variety of phenols are directly converted to the corresponding 2-methylthio-3-trifluoromethylbenzo[b]furans by new triflic-anhydride-mediated extended Pummerer annulation reactions with trifluoromethylketene dithioacetal monoxide. The methylthio group of the products undergoes further transformations, which increase the diversity of available trifluoromethylbenzo[b]furans.

Regioselective stannylmetalation of acetylenes in the presence of transition-metal catalyst

Abstract Me2AlSPh or Me2AlSeMe adds to α,β-unsaturated carbonyl compounds in 1,4-fashion. The resulting aluminium enolates react with aldehydes effectively to afford the adducts of the title anion after formal PhSH (or MeSeH)-elimination.