Catalyst- and solvent-free hydrophosphination and multicomponent hydrothiophosphination of alkenes and alkynes
作者:Yanina Moglie、María José González-Soria、Iris Martín-García、Gabriel Radivoy、Francisco Alonso
DOI:10.1039/c6gc00903d
日期:——
The hydrophosphination of carbon-carbon multiple bonds has been generally performed under acid, base or metal catalysis in different solvents. Herein, alkyl and alkenyl tertiary phosphines are obtained by the addition...
Allosteric effects in asymmetric hydrogenation catalysis? Asymmetric induction as a function of the substrate and the backbone flexibility of C1-symmetric diphosphines in rhodium-catalysed hydrogenations
作者:Angharad Baber、Johannes G. de Vries、A. Guy Orpen、Paul G. Pringle、Karl von der Luehe
DOI:10.1039/b607479k
日期:——
The new unsymmetrical, optically active ligands 1,2-C2H4(PPh2)(2′R,5′R-2′,5′-dimethylphospholanyl) (Laa) and 1,3-C3H6(PPh2)(2′R,5′R-2′,5′-dimethylphospholanyl) (Lbb) form complexes of the type [Rh(L)(cyclooctadiene)][BF4] where L = Laa (1a) or Lbb (1b), [PtCl2(L)] where L = Laa (2a) or Lbb (2b) and [PdCl2(L)] where L = Laa (3a) or Lbb (3b). The crystal structures of 2a and 2b show the chelate ligand backbones adopt δ-twist and flattened chair conformations respectively. Asymmetric hydrogenation of enamides and dehydroaminoesters using 1a and 1b as catalysts show that the ethylene-backboned diphosphine Laa gives a more efficient catalyst in terms of asymmetric induction than the propylene-backboned analogue Lbb. The greatest enantioselectivities were obtained with 1a and enamide substrates with ees up to 91%. Substrate-induced conformational changes in the Rh–diphosphine chelates are proposed to explain some of the ees observed in the hydrogenation of enamides.
Synthesis and Electrochemical Studies of Cobalt(III) Monohydride Complexes Containing Pendant Amines
作者:Eric S. Wiedner、John A. S. Roberts、William G. Dougherty、W. Scott Kassel、Daniel L. DuBois、R. Morris Bullock
DOI:10.1021/ic401232g
日期:2013.9.3
CoI complex [CoI(L2)(CH3CN)]+. Under voltammetric conditions, the reduced cobalt hydride reacts with a protic solvent impurity to generate H2 in a monometallic process involving two electrons per cobalt. In contrast, under bulk electrolysis conditions, H2 formation requires only one reducing equivalent per [HCoIII(L2)(CH3CN)]2+, indicating a bimetallic route wherein two cobalt hydride complexes react
两个新的四膦配体P n C-PPh 2 2 N Ph 2(1,5-二苯基-3,7-双((二苯基膦基)烷基)-1,5-二氮杂3,7-二磷环辛烷;烷基=(CH 2)2,n= 2(L 2);(CH 2)3,n= 3(L 3))已经合成。这些配体与钴的配位得到配合物[Co II(L2)(CH 3 CN)] 2+和[Co II(L3)(CH 3 CN)] 2+,它们经KC 8还原得到[Co I(L2)(通道3CN)+和[Co I(L3)(CH 3 CN)] +。Co I配合物的质子化提供[HCo III(L2)(CH 3 CN)] 2+和[HCo III(L3)(CH 3 CN)] 2+。使用数字仿真分析的[HCo III(L2)(CH 3 CN)] 2+的循环伏安法与涉及从[HCo II(L2)(CH 3)的可逆乙腈解离的E r C r E r还原机理一致CN)] +并导致形成HCo I(L2)。HCo
Synthesis and Reactivity of Tris(Hydroxymethyl)Phosphine-Mimicking Nonsymmetrical Diphosphine Ligands
作者:Aike Nijland、Steven van Zutphen、Duncan Carmichael
DOI:10.1080/10426507.2014.983597
日期:2015.6.3
As part of a study to obtain well-defined tris(hydroxymethyl)phosphine (THP)-inspired ligands, a new nonsymmetrical diphosphine featuring two hydroxymethyl functional groups on one phosphine terminus has been synthesized. A double formylation reaction was employed to effect the hydroxymethylation of the primary phosphine function in Ph2P(CH2)2PH2 and furnish the target bis(hydroxymethyl)phosphanyle