Takao Ikariya

Ruthenium (II)-BINAP complex catalyzed asymmetric hydrogenation of unsaturated dicarboxylic acids

Abstract Asymmetric hydrogenation of unsaturated dicarboxylic acids employing ruthenium-BINAP complexes as catalyst gave optically active 2-alkylsuccinic acids with high enantioselectivities.

Preparation and properties of hydride triphenyl-phosphine ruthenium complexes with 3-formyl (or acyl) propionate [RuH(ocochrchrcor′)(PPh3)3] (R H, CH3, C2H5; R H, CH3, C6H5) and with 2-formyl (or acyl) benzoate [RuH(o-OCCOC6H4COR′)(PPh3)3] (R′ H, CH3)

Abstract Reactions of Five-membered cyclic dicarboxylic anhydrides, such as phthalic anhydride and succinic anhydride, with RuH2(PPh3)3] and 3-formyl propionate [RuH(OCOCH2CH2CHO)(PPh3)3], via the Cue5f8O bond cleavage of the anhydrides. Similar reactions of methylsuccinic anhydride or ethylsuccinic anhydride with RuH2(PPh3)4 afford mixtures of the isomers [RuH(OCOCHRCH2CHO)(PPh3)3] and RuH(OCOCH2CHRCHO)(PPh3)3] (R ue5fb CH3 or C2H5), in ca. 3 to 1 molar ratio in each reaction. Complexes with 2-acyl benzoate or 3-acyl propionate ligands formulated as [RuH(o-OCOC6H4COCH3(PPH3)3] or [RuH(OCOCH2CH2COR/t)(PPh3)3](R/t ue5fb CH3, C6H5) are prepared from the reaction of corresponding 2-acyl benzoic or 3-acyl propionic acids with RuH2(PPh3)4. Upon contact with hydrogen at elevated pressure, or with hydrogen chloride or carbon monoxide at atmospheric pressure, these complexes release the corresponding γ-lactones, which are formed through the reduction of formyl or acyl groups in the carboxylate ligands followed by intramolecular condensations. Hydrogenation of 3-acyl propionic acids using ruthenium(II) complexes as catalyst gives γ-substituted γ-lactones in high yields.

Catalytic asymmetric hydrogenation of cyclic anhydrides using ruthenium (II) chiral phosphine complex

Abstract Optically active γ- and δ-lactones are obtained by the hydrogenation of five- and six-membered cyclic anhydrides using a Ru(II) complex with chiral phosphine ligand, DIOP, as a catalyst.

Asymmetric hydrogenation of prochiral carboxylic acids catalyzed by the five-coordinate ruthenium(II)-hydride complex [RuH(binap)2]PF6 (binap = (R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl)

Abstract The five-coordinate complex [RuH(binap)2]PF6 (I, binap = (R)- or (S)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) has been found to have sufficient catalytic activity for asymmetric hydrogenation of itaconic acid and other prochiral carboxylic acids under mild conditions. The catalytic hydrogenation of itaconic acid by I was examined under a variety of conditions, and the addition of triethylamine was found to effect high enantioselectivities (> 90% ee). 1H and 31P NMR examinations of reaction mixtures of I and itaconic acid under conditions similar to the hydrogenation suggested the formation of ruthenium species containing one binap chelate.

Highly regioselective lactone formation catalyzed by ruthenium complexes. An application to synthesis of arylnaphthalene lignans

Abstract Ruthenium catalyzed hydrogenation of cyclic anhydrides and dehydrogenation of diols have been successfully applied to the highly regioselective synthesis of arylnaphthalene lignans.

Catalytic regioselective dehydrogenation of unsymmetrical α,ω-diols using ruthenium complexes

Abstract Ruthenium complex catalyzed regioselective dehydrogenation of unsymmetrically substituted 1,4- and 1,5-diols in the presence of α,β-unsaturated ketone as a hydrogen acceptor and triethylamine gave β-substituted γ-lactones and γ-substituted δ-lactones as major products, respectively.

Preparation of a new type of imidoruthenium hydride complex

Abstract Treatment of RuH 2 (PPh 3 ) 4 with cyclic imides such as d -camphorimide, phthalimide, succinimide and methyl succinimide gave a new type of imidoruthenium hydride complex, RuH(imido)(PPh 3 ) 3 , which has an imido ligand acting as bidentate ligand coordinated through its nitrogen and oxygen atoms.

WCl6/LiAlH4 Promoted transformation of imines into secondary and tertiary amines

Abstract The reaction of WCl6/LiAlH4 with imines, R′Nue5fbCHR, gave tertiary amines, R′N(CH2R)2, and secondary amines, R′NHCHRCH2R. Isotope labeling experiments revealed that the reaction involved two types of azatungstenacyclobutanes, WNR′CHRC HR and WCHRNR′C HR, produced from the reaction of an alkylidene tungsten intermediate with the imine Cue5fbN double bond. Formation of these metallacyclobutanes is highly dependent on the solvent used.