Yoshiki Ohshiro

Stereoselective synthesis of vinylphosphonate

Abstract Dialkyl vinylphosphonate is stereoselectively prepared by palladium-catalyzed reaction of vinyl bromide with dialkyl phosphite.

Oxovanadium-induced oxidative desilylation for the selective synthesis of 1,4-diketones

Silyl enol ethers underwent the VO(OR)Cl2-induced homo- or cross-coupling giving 1,4-diketones selectively via one-electron oxidative desilylation.

Oxidative decarboxylation of α-amino acids with coenzyme PQQ

Abstract Oxidative decarboxylation of α-phenylglycine with coenzyme pqq was performed catalytically in the presence of CTAB under mild conditions to give benzaldehyde and benzoic acid.

Palladium-catalyzed reaction of allylic ammonium bromides with nucleophiles

Abstract The reactions of allylic triethylammonium bromides and dimethylsulfonium bromide with carbon nucleophiles were catalyzed by tetrakis(triphenylphosphine)palladium to afford olefinic esters and ketones.

Micelle enhanced oxidation of amines by coenzyme PQQ

Abstract Nonezymatic oxidation of amines with the coenzyme PQQ is enhanced by a cationic surfactant to give the corresponding carbonyl compounds, suggesting that the micelle presents a good environment for oxidation with PQQ. The similar reaction is applicable to alcohols though an efficiency is not so high.

Reactions of diphenylcyclopropenone with ketenes in the presence of nickel tetracarbonyl

Abstract Reactions of diphenylcyclopropenone with ketenes in the presence of catalytic amounts of nickel tetracarbonyl have been studied. In these reactions, 1 : 1 cycloadducts, cyclopentene-1,2-dione derivatives, were obtained in yields above 80%. The cycloaddition reactions were significantly affected by solvents, and DMF was the most suitable solvent. Iron pentacarbonyl did not act as a catalyst. Reaction mechanisms are discussed.

Synthesis of vinylsilanes by palladium-catalyzed reaction of trimethylsilylallyl acetates with nucleophiles

Abstract Treatment of 1-trimethylsilylallyl and 3-trimethylsilylallyl acetates with nucleophiles (active methylene compounds and enamines) in the presence of a catalytic amount of Pd(PPh3)4 affords vinylsilane derivatives selectively.

A novel catalytic system for oxygenation with molecular oxygen induced by transition metal complexes with a multidentate N-heterocyclic podand ligand

Abstract An efficient system for the catalytic epoxidation reaction of olefins with molecular oxygen was achieved by the utilization of FeCl 2 and the N -heterocyclic podand ligand, N,N′ -bis{2-(4-imidazolyl)ethyl}-2,6-pyridinedicarboxamide (BIPA), without the need for a co-reductant. The pyridyl-substituted N -heterocyclic podand ligand, N,N′ -bis{2-(2-pyridyl)ethyl}-2,6-pyridinedicarboxamide (2-BPEPA) was useful in the Co(OAc) 2 -catalyzed selective oxygenation of phenols to the corresponding p - or o -quinones with molecular oxygen. Efficiency of the oxygenation catalysts largely depends on the coordination interaction with the heterocyclic moieties of the podand ligands.

Novel generation of azomethine ylide from N-(α-silylbenzyl)amide by silicon shift: an equivalent of nitrile ylide

Abstract Azomethine ylides were generated from N -(α-silylbenzyl)amides by thermal silicon shift to the oxygen and trapped with dipolarophiles to give the same products as those from the corresponding nitrile ylides via elimination of silanol.

A novel system for oxygenation. Effect of multidentate podand ligand in transition metal catalyzed epoxidation with molecular oxygen

Abstract An efficient system for the catalytic epoxidation reaction of olefins with molecular oxygen was achieved by utilization of FeCl2 or Co(OAc)2 and the N-heterocyclic podand ligand, N,N′-bis{2-(4-imidazolyl)ethyl}-2, 6-pyridine-dicarboxamide (BIPA), without the need for a coreductant. The multidentate coordination of BIPA is considered to serve an important role in the oxygenation.