Yasuo Wakatsuki

Recent developments in organolanthanide polymerization catalysts

This review describes recent advances in the synthesis and polymerization chemistry of organolanthanide complexes (including those of scandium and yttrium), with emphasis being placed on the complexes that show novel activity and selectivity in polymerization reactions.

Cobalt metallocycles : I. One-step and stepwise synthesis of cobaltacyclopentadiene complexes from acetylenes

Abstract (π-Cyclopentadienyl) (triphenylphosphine) cobaltacyclopentadiene complexes having a variety of substituents have been prepared from substituted acetylenes and (π-cyclopentadienyl)bis(triphenylphosphine)cobalt. In some cases monoacetylene complexes have been isolated and by addition of other acetylenes to the monoacetylene complexes, cobalt metallocycles consisting of two diffferent acetylene units have been prepared. The structures of all cobaltacyclopentadiene isomers have been determined by NMR spectra and/or by degradation to organic compounds.

Ruthenium-Catalyzed Intermolecular Hydroamination of Terminal Alkynes with Anilines: A Practical Synthesis of Aromatic Ketimines.

Without solvent and in the open air, the hydroamination of phenylacetylene with aniline in the presence of [Ru(3)(CO)(12)]/NH(4)PF(6) proceeds with high regioselectivity [Eq. (1)]. Simple distillation gives a product with greater than 99 % purity in an excellent yield. The application of this method to a new two-component reaction gives the important class of substances: the quinolines.

Cobalt metallocycles: II. Diels—alder type reaction of cobaltacyclopentadienes with olefins

Abstract Several cobaltacyclopentadiene complexes, (π-C5H5)(PPH3)( CoCRCRCRC R) (I), reacted with olefins (ethylene, propylene, styrene, methyl acrylate, dimethyl maleate) to give corresponding cyclohexadiene complexes. The first step of the reaction involves replacement of triphenylphosphine by olefin. Therefore the cycloaddition reaction takes place between two ligands bonded simultaneously to a transition metal. Endo—exo stereoselectivity was examined when dimethyl maleate was used as dienophile.

Lanthanide(II) complexes bearing mixed linked and unlinked cyclopentadienyl–monodentate-anionic ligands

Abstract This paper is intended to provide an overview on recent progress in the chemistry of divalent lanthanide complexes bearing mixed (linked and unlinked) cyclopentadienyl–monodentate-anionic ligands. The synthesis, structures, and one-electron-transfer and polymerization reactions of these complexes are described.

A practical one-pot synthesis of 2,3-disubstituted indoles from unactivated anilines

2-Substituted-3-methyl indoles are synthesized with good regioselectivity from readily available substrates and catalysts, i.e. the reaction of anilines with propargyl alcohols in the presence of 0.36–1 mol% Ru3(CO)12.

Efficient transformation of propargylic alcohols to α,β-unsaturated aldehydes catalyzed by ruthenium/water under neutral conditions

Abstract α,β-Unsaturated aldehydes were selectively obtained in high yields from propargylic alcohols in aqueous solutions using RuCpCl(PR 3 ) 2 (Cp=η 5 -C 5 H 5 ) as a catalyst. Of the tert -phosphine ligands examined, PMe 3 gave the most satisfactory results. Typically, RuCpCl(PMe 3 ) 2 (5 mol%) catalyzed the transformation of oct-1-yn-3-ol at 100°C to give 2-octenal in an isolated yield of 85% ( E / Z =80/20).

Some reactions of π-cyclopentadienylbis(triphenylphosphine) rhodium(I)

Abstract Reactions of π-cyclopentadienylbis(triphenylphosphine)rhodium(I) (I) with alkyl halides, olefins, acetylenes, carbon disulfide and elementary sulfur have been investigated. Methyl iodide gives the oxidative-addition product [πC5H5 Rh(PPh3)2CH3]I but isopropyl iodide produces the alkyl substituted-cyclopentadienyl complex (π-i-C3H7C5H4)Rh(PPh3)I2. Under a nitrogen atmosphere, olefins and acetylenes give compounds of the composition π-C5H5 Rh(PPh3)(L) (L = CH2—CHCN, CH2—CHCO2CH3, CH3O2—CCOO2CH3). In the presence of air, however, complexes of the composition π-C5H5Rh(L)2 (L = CH2—CHCN, CH2—CHCO2CH3, CH2—C(CH3)CN) and π-C5H5Rh(L)3 (L = CH3O2 CC—CCO2 CH3, PhC—CCO2 CH3) are formed. The reaction of carbon disulfide or sulfur with (I) also gives the compounds π-C5H5Rh(PPh3)(L) (L = CS2, CS3, S5).

DIE ERSTE ANTI-MARKOWNIKOW-HYDRATISIERUNG TERMINALER ALKINE : RUTHENIUM(II)/ PHOSPHAN-KATALYSIERTE BILDUNG VON ALDEHYDEN

Erst das zugesetzte Phosphan, z.B. Pentafluorphenyldiphenylphosphan oder das Natriumsalz von 3,3′,3″-Phosphinidintris(benzolsulfonsaure), ermoglicht die effiziente Ruthenium(II)-katalysierte Hydratisierung terminaler Alkine zu Aldehyden uber eine bislang nicht beschriebene Anti-Markownikow-Addition von Wasser [Gl. (a)]. Als katalytisch aktive Spezies werden Komplexe vom Typ [RuCl2(PR2′R″)x] diskutiert. R=Alkyl, Ph.

Some organometallic chemistry of ruthenium(II)

Abstract Stoichiometric and catalytic reaction of Ru(II) phosphine complexes with alkynes, olefins, and enynes are described. The hydride complex RuCl(CO)H(PPh3)3 (1) reacts with the double bond of a cis-enyne whereas it reacts with triple bonds of trans-enynes. Metathesis of vinyl silanes with olefins are catalyzed by 1 where β-Si elimination is the key step. Dimerizations of tBu- and Me3Si-substituted acetylanes into the corresponding butatrienes are catalyzed by Ru(II) active species as studied by isolation of the intermediates. A model reaction for the crucial step of the catalytic cycle, formation of a Ru vinylidene complex from acetylene, has been fully simulated by ab initio-MO calculations.