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Journals and Conferences
In this tutorial review recent mechanistic studies on transition metal-catalyzed hydrogen transfer reactions are discussed. A common feature of these reactions is that they involve metal hydrides, which may be monohydrides or dihydrides. An important question is whether the substrate coordinates to the metal (inner-sphere hydrogen transfer) or if there is a… (More)
Chiral iridium catalysts have now been used in the asymmetric hydrogenation of largely unfunctionalized olefins for a decade. Recently, they have also been applied to substrates with more exotic functional groups, including non-coordinating ones. These, unlike coordinating substituents, cannot direct asymmetric hydrogenation by rhodiumor ruthenium-based… (More)
This account discusses the progress made in the asymmetric hydrogenation of minimally functionalised terminal olefins as a new, alternative, sustainable and direct strategy for preparing enantioenriched hydrocarbons. It discusses the latest development in catalyst design, from the initial discovery of lanthanide catalytic precursors, through the use of… (More)
The asymmetric Heck reaction using P,N-ligands has been studied by a combination of theoretical and experimental methods. The reaction follows Halpern-style selectivity; that is, the major isomer is produced from the least favored form of the pre-insertion intermediate. The initially formed Ph-Pd(P,N) species prefers a geometry with the phenyl trans to N.… (More)
A range of saturated chiral azacycles has been prepared in high yield and with high selectivity from simple starting materials. A modular approach with ring-closing metathesis as a key step was used to produce a number of five-, six-, and seven-membered cyclic alkenes. Asymmetric hydrogenation catalyzed by N,P-ligated iridium complexes gave saturated… (More)
The first Ir-catalyzed asymmetric hydrogenations of vinyl boronates have been performed using low catalyst loadings (0.5 mol%) and pressure (as low as 1 bar). Good selectivities (76-98% ee) were obtained for a range of substrates.
[reaction: see text] Enol phosphinates, which are structural analogues of enol acetates, have for the first time been employed as substrates for Ir-catalyzed asymmetric hydrogenation. A number of enol phosphinates have been synthesized and reduced successfully with up to and above 99% ee.
Diphenylvinylphosphine oxides and di- and trisubstituted vinylphosphonates have been employed as substrates in iridium-catalyzed asymmetric hydrogenations. Complete conversions and excellent enantioselectivities (up to and above 99% ee) were observed for a range of substrates with both aromatic and aliphatic groups at the prochiral carbon. We have also… (More)
New nitrogen- and sulfur-containing compounds, bicyclic and monocyclic, were prepared and evaluated as ligands in the transfer hydrogenation of acetophenone. Utilising [Ir(COD)Cl]2 as metal precursor the best result, 80% ee, was obtained using a bicyclic sulfoxide ligand.
The reaction mechanism of the iridium-phosphanooxazoline-catalyzed hydrogenation of unfunctionalized olefins has been studied by means of density functional theory calculations (B3LYP) and kinetic experiments. The calculations suggest that the reaction involves an unexpected Ir(III)-Ir(V) catalytic cycle facilitated by coordination of a second equivalent of… (More)