Tsuneaki Yamagata

Preparation of optically active peralkyldiphosphines and their use, as the rhodium(I) complex, in the asymmetric catalytic hydrogenation of ketones

Abstract Two types of the optically active peralkyldiphosphine, 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(dialkylphosphino)butane (Rdiop 3) and N-(N′-substituted carbamoyl-4-dicyclohexylphosphino-2-dicyclohexylphosphinomethylpyrrolidine (R-Cycapp 8), have been prepared by various synthetic methods. Rhodium(I) complexes of 3 and 8 showed high catalytic activity for hydrogenation of various kinds of prochiral ketones, which were reduced smoothly to the corresponding optically active hydroxy compounds, under hydrogen at atmospheric pressure and ambient temperature. The neutral rhodium(I) complexes (diphosphine-RhN) hydrogenated α-ketoamides and α-ketopantolactone in fairly high optical yields (66–77%ee). In the hydrogenation of N-(α-ketoacyl)-α-amino esters, the Cydiop-RhN catalyst showed a marked contrast to the diop-RhN system; in the hydrogenation of the methyl ester of N-(phenylglyoxyl)-(S)-α-phenylalanine, 72%de was attained with little double asymmetric induction by the chiral center in the substrate.

Synthesis, characterisation and structure of square-planar palladium(II) complexes with phosphine–pyridine hybrid ligands o-Ph2PC6H4CH2O(CH2)nC5H4N-2 (n= 1–3). Isolation of the first transition-metal complex with a trans-chelating bidentate PN ligand

The reaction of Na2[PdCl4] or [PdCl2(PhCN)2] with an equimolar amount of new bidentate hybrid ligands having a P and a N donor atom capable of trans chelation, o-Ph2PC6H4CH2O(CH2)nC5H4N-2 (n= 1–3), gave mainly the 1 : 1 complex [PdCl2{o-Ph2PC6H4CH2O(CH2)nC5H4N-2}]. Depending on the length of the backbone connecting the phosphino and the pyridyl groups, cis- or trans-co-ordinated complexes were mainly formed; when n= 1 the cis complex 1 was formed, but the ligands with longer bridges gave the trans complexes 2 and 3 respectively as the main products. From the reaction of the palladium(II) complex with o-Ph2PC6H4CH2O(CH2)nC5H4N-2 (n= 2 or 3) the trinuclear complexes [Pd3Cl6{o-Ph2PC6H4CH2O-(CH2)nC5H4N-2}2]4(n= 2) and 5(n= 3) were also obtained as minor products and the cis-chelated complexes analogous to 1 could not be isolated. The reaction of Na2[PdCl4] with 2 equivalents of o- Ph2PC6H4CH2O(CH2)3C5H4N-2 gave quantitatively the 1 : 2 complex trans-[PdCl2{o-Ph2PC6H4CH2O-(CH2)3C5H4N-2}2]7 in which the ligand is bound only through the P atom. This complex is in equilibrium with the trans 1 : 1 complex 3 in solution, dissociating one molecule of the ligand (Keq= 5.6 × 10–3 mol dm–3, 35 °C). On heating in CH2Cl2-tetrahydrofuran or diethyl ether, 3 partially isomerised to the dinuclear complex [Pd2Cl4{µ-o-Ph2PC6H4CH2O(CH2)3C5H4N-2}2]6, in which the hybrid ligands act as bridges. The crystal structures of 1, 3 and 6 were determined; 3 is the first example of a transition-metal complex with a trans-spanning chelate phosphine-pyridine hybrid ligand. The reaction of the ligand o-Ph2PC6H4CH2-O(CH2)3C5H4N-2 with K2[PtCl4], in contrast to the palladium complexes, always gave the 1 : 2 complex trans-[PtCl2{o-Ph2PC6H4CH2O(CH2)3C5H4N-2}2]8 in good yield regardless of the ligand: Pt ratio. It did not dissociate in solution and the trans-chelated complex analogous to 3 could not be isolated even from the reaction of K2[PtCl4] with an equimolar amount of the ligand o-Ph2PC6H4CH2O(CH2)3C5H4N-2.

Stereoselective reaction of ±-7-Phenyldinaphtho[2,1-b;1′,2′-d]phosphole with an optically active palladium complex. Molecular structure and fluxional behavior of Pd(S)- C6H4CH(CH3)N(CH3)2(P)-PPh(C20H12) Cl

Abstract Reaction of ±-7-phenyldinaphtho[2,1- b ;1′,2′- d ]phosphole ( 1 ) with one-half equivalent of an optically active palladium complex, Pd[( S )-C 6 H 4 CH(CH 3 )N(CH 3 ) 2 ](μ-Cl) 2 (( S )- 3a ), proceeded stereoselectively to give one of the diastereomers, Pd( S )-C 6 H 4 CH(CH 3 )N(CH 3 ) 2 ( P )-PPh(C 20 H 12 )Cl (( S )( P ) 4a ), accompanying racemization of 1 . The X-ray crystallographic analysis of ( S ( P )- 4a determined the absolute configuration of the coordinated phosphole unequivocally to be P . The fluxional behavior of 4a and the related complex is also discussed.

A new rhodium trinuclear complex containing highly protected hydroxo groups, [{Rh(binap)}3(µ3-OH)2]CIO4, responsible for deactivation of the 1,3-hydrogen migration catalyst of allylamine [binap = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl]

A new stable rhodium trinuclear complex, [{Rh(binap)}3(µ3-OH)2]ClO4[binap = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl](2), formed when water deactivates the RhI–binap complex catalysed asymmetric 1,3-hydrogen migration of allylamine, has been isolated; and X-ray structural analysis of the deuterium derivative [{Rh[(+) binap]}3(µ3-OD)2]ClO4 revealed a unique structure with two highly protected µ3-hydroxo groups.

Facile Oxidative Addition of O−H Bonds of Methanol and Water to IrI Complexes Having Peraryldiphosphane Ligands

A new piece in the puzzle. Hydrido(alkoxo) complexes of late transition metals have often been postulated as intermediates or transition states in the catalytic hydrogenation of carbonyl compounds and catalytic hydrogen transfer reactions. Here the facile oxidative addition of the O-H bonds of alcohol and water to iridium(I) complexes of peraryldiphosphanes [Eq. (a)] is reported and the resulting complexes are described. R=H, Me.

Preparation of cationic (E)-σ-alkenyi palladium complexes having a P–O–N or a P–O–P tridentate ligand as a stabilized intermediate of palladium-catalysed stereoselective addition of methanol to acetylenes; characterisation, X-ray analysis and the reaction pathway

Cationic (E)-σ-alkenyl palladium complexes 1 having a P–O–N or a P–O–P tridentate ligand are prepared stereoselectively from cis-PdCl2(PNn= 1)[PN =o-Ph2PC6H4CH2O(CH2)n-2-C5H4N-P,N] or cis-PdCl2(POP)[POP = Ph2P(CH2)2O(CH2)2PPh2-P,P] and internal alkynes in the presence of AgPF6 and MeOH; the X-ray crystal structure of 1c is reported and a stepwise abstraction of chloride ligands for the formation of 1 is proposed.

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%).

Reductive dimerization of dialkyl acetylenedicarboxylate catalyzed by [Rh(binap)(MeOH)2]ClO4 in methanol

Abstract Cationic Rh(I) complex [Rh(binap)(MeOH) 2 ]ClO 4 catalyzes reductive dimerization of dialkyl acetylenedicarboxylates 1 to give 1,2,3,4-tetrakis(alkoxycarbonyl)-1,3-butadienes 2 in methanol selectively.

Molecular structure and absolute configuration of (P)‐7‐phenyldinaphtho[2,1‐b;1',2'‐d]phosphole

An X-ray diffraction study of a crystal of the title compound, C 26 H 17 P, showed that the naphthyl rings bend away from each other and deviate significantly from planarity; the whole molecule has helical chirality. The crystal chosen for the crystallographic analysis had P absolute configuration, indicating that spontaneous resolution had occurred during crystallization

Leichte oxidative Addition von Methanol und Wasser an Peraryldiphosphan‐IrI‐Komplexe

Ein neues Stuck des Puzzles: Hydrido(alkoxo)-Komplexe spater Ubergangsmetalle sind haufig als Intermediate und Ubergangszustande bei katalytischen Hydrierungen von Carbonylverbindungen und katalytischen Wasserstoffubertragungen postuliert worden. Durch oxidative Addition der OH-Gruppen von Alkohol und Wasser an Peraryldiphosphaniridium(I)-Komplexe [Gl. (a)] wurden derartige Komplexe erhalten. R=H, Me.