Hidenori Kumobayashi

New Chiral Diphosphine Ligands Designed to have a Narrow Dihedral Angle in the Biaryl Backbone

A series of novel optically active diphosphine ligands, (4,4′-bi-1,3-benzodioxole)-5,5′-diylbis(diarylphosphine)s (6), which are called SEGPHOS, has been designed and synthesized with dihedral angles in the Ru complexes being less than that in the corresponding BINAP-Ru complex. The stereorecognition abilities of SEGPHOS-Ru complex catalysts in the asymmetric catalytic hydrogenation of a wide variety of carbonyl compounds are superior to those observed with BINAP-Ru complex catalysts.

Ruthenium-catalyzed oxidation of β-lactams with molecular oxygen and aldehydes

Abstract The RuCl3 catalyzed reaction of β-lactams in the presence of acetaldehyde and molecular oxygen in an acid and ethyl acetate under buffer conditions gives the corresponding 4-acyloxy β-lactams highly efficiently.

Asymmetric hydrogenation of unsaturated carbonyl compounds catalyzed by BINAP-Ru(II) complexes. Enantioselective synthesis of γ-butyrolactones and cyclopentanones

Abstract Asymmetric hydrogenation of 2- and 4-alkylidene-γ-butyrolactones and 2-alkylidenecyclopentanones catalyzed by BINAP—Ru(II) complexes affords the corresponding γ-butyrolactones and cyclopentanones in 94–98% ee. Hydrogenation of (E)- and (Z)-2-propylidene-γ-butyrolactone catalyzed by the same catalyst gave the products with the same absolute configuration and in almost equal enantioselectivities, which shows that olefin geometry does not affect the stereochemistry and enantioselectivity.

Chemoselective asymmetric hydrogenation of α,β-unsaturated carbonyl compounds to allylic alcohols catalysed by [Ir(binap)(cod)]BF4-aminophosphine

Asymmetric hydrogenation of (E)-4-phenyl-3-buten-2-one by use of [Ir(binap)(cod)]BF4 and o-di-methylaminophenyldiphenylphosphine afforded (E)-4-phenyl-3-buten-2-ol in 97% chemoselectivity and in 65% enantiomeric excess. A mixed ligand iridium dihydride complex containing both BINAP and the aminophosphine ligand has been shown to be the catalytically active species.

Osmium-catalyzed oxidation of β-lactams with peroxides

Abstract Osmium-catalyzed oxidation of β-lactams with peroxides in acetic acid gives the corresponding 4-acetoxy β-lactams, which are versatile synthetic intermediate of carbapenem antibiotics, in good to excellent yields.

Asymmetric synthesis of (R)-2-chloro-1-(m-chlorophenyl)ethanol using acetone powder of Geotrichum candidum

The asymmetric synthesis of (R)-2-chloro-1-(m-chlorophenyl)ethanol, a precursor for a key intermediate of an important class of drugs, was achieved by reduction of the corresponding ketone using an acetone powder of Geotrichum candidum with 98% ee and 94% yield based on the starting amount of ketone.

Enantioselective hydrogenation of acyclic aromatic ketones catalyzed by BINAP—Ir(I)—aminophosphine systems

Abstract Enantioselective hydrogenation of acyclic aromatic ketones PhCOR (R = alkyl or cycloalkyl group) has been accomplished by using the catalytic systems derived from [Ir(( S )-binap)(cod)]BF 4 or [Ir(( S )-H 8 -binap)(cod)]BF 4 [H 8 -BINAP = 2,2′-bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl] and bis( o -dimethylaminophenyl)phenylphosphine. The enantiomeric excesses as well as the absolute configurations of the corresponding alcohols depend markedly on the steric size of the alkyl or cycloalkyl groups, and the highest ee s are obtained when the alkyl groups R are i -Pr (84%, R ) and c -C 6 H 11 (80%, R ), respectively.

Cationic rhodium(I) complex-catalysed asymmetric isomerisation of allylamines to optically active enamines

The cationic rhodium(I) complex(+)- or (–)-2,2′bis(diphenylphosphino)-1,1′-binaphthyl(cyclo-octa-1,5-diene)rhodium perchlorate, effectively catalyses the isomersiation of N,N-diethylnerylamine or N,N-diethylgeranylamine to produce optically active N,N-diethylcitronellal-(E)-enamine with excellent enantioselectivity (> ca. 95% enantiomeric excess) and chemoselectivity (> ca. 98%).