Preparation of novel Sulfur and phosphorus containing oxazolines as ligands for asymmetric catalysis

Allen, J. T.; Dawson, Graham; Frost, Christopher G.; Williams, Ionathan M.J.; Coote, Steven J.

doi:10.1016/s0040-4020(01)80795-x

Cited by 89 publications

(28 citation statements)

References 27 publications

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“…OxaPN was synthesized according to a published procedure. [12] Characterization Electrochemical set-up for voltammetry: Electrochemical experiments were carried out in a three-electrode cell connected to a Schlenk line. The cell was equipped with a double envelope to maintain a constant temperature (Lauda RC20 thermostat).…”

Section: Resultsmentioning

confidence: 99%

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Oxidative Addition of Palladium(0) Complexes Generated from [Pd(dba)2] and P-N Ligands: A Kinetic Investigation

2000

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The major complex formed in solution from [[Pd0(dba)2]+1P-N] mixtures is [Pd0(dba)(P-N)] (dba=trans,trans-dibenzylideneacetone; P-N=PhPN, 1-dimethylamino-2-diphenylphosphinobenzene; FcPN, N,N-dimethyl-1-[2-(diphenylphosphino)ferrocenyl]methylamine; OxaPN, 4,4'-dimethyl-2-(2-diphenylphosphinophenyl)-1,3-oxazoline). Each complex consists of a mixture of isomers involved in equilibria: two 16-electron rotamer complexes [Pd0(eta2-dba)(eta2-P-N)] and one 14-electron complex [Pd0(eta2-dba)(eta1-P-N)] observed for FcPN and OxaPN. [Pd0(dba)(PhPN)] and [SPd0(PhPN)] (S solvent) react with PhI in an oxidative addition: [SPd0(PhPN)] is intrinsically more reactive than [Pd0(dba)(PhPN)]. This behavior is similar to that of the bidentate bis-phosphane ligands. When the PhPN ligand is present in excess, it behaves as a monodentate phosphane ligand, since [Pd0(eta2-dba)(eta1-PhPN)2] is formed first by preferential cleavage of the Pd-N bond instead of the Pd olefin bond. [Pd0(eta1-PhPN)3] is also eventually formed. [Pd0(dba)(FcPN)] and [Pd0(dba)(OxaPN)] are formed whatever the excess of ligand used. [SPd0(FcPN)] and [SPd0)(OxaPN)] are not involved in the oxidative addition. The 16-electron complexes [Pd0(eta2-dba)(eta2-FcPN)] and [Pd0(eta2-dba)(eta2-OxaPN)] are found to react with PhI via a 14-electron complex as has been established for [Pd0(eta2-dba)(eta1-OxaPN)]. Once again, the cleavage of the Pd-N bond is favored over that of Pd-olefin bond. This work demonstrates the higher affinity for [Pd0(P-N)] of dba compared with the P-N ligand, and emphasizes once more the important role of dba, which either controls the concentration of the most reactive complex, [SPd0(PhPN)], or is present in the reactive complexes, [Pd0(dba)(FcPN)] or [Pd0(dba)(OxaPN)], and thus contributes to their intrinsic reactivity.

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Section: Resultsmentioning

confidence: 99%

“…FcPN and OxaPN are models for the aminoferrocenylphosphane [11] and phosphinooxazoline [12] ligands, respectively, that are used in enantioselective cross-coupling reactions, [5] allylic nucleophilic substitutions, [6±8] and Heck reactions.…”

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confidence: 99%

Oxidative Addition of Palladium(0) Complexes Generated from [Pd(dba)2] and P-N Ligands: A Kinetic Investigation

2000

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“…Synthesis via the Grignard reagent procedure also furnished the compound 5 as the main product (Scheme 2). Therefore, we employed the 2-(2-fluorophenyl)-oxazoline 2f as precursor to react with the phosphine reagent KPPh 2 in refluxing THF [11], and fortunately, the ligand 3f was obtained in good yield, though the homo-coupling reaction could not be completely avoided. The racemic ligands 3a and 3b were obtained from the racemic starting materials, while the chiral ligand 3f was synthesized using (S)-(+)-2-amino-2-phenylethanol and 2-fluorobenzoic acid as starting materials.…”

Section: Synthesis Of the Phox Ligands 3a-fmentioning

confidence: 99%

Nickel(II) complexes bearing phosphinooxazoline ligands: Synthesis, structures and their ethylene oligomerization behaviors

Tang

Zhang

Jie

et al. 2005

Journal of Organometallic Chemistry

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“…They are synthesized from chiral amino alcohols and benzonitrile or bromobenzonitrile: the phosphine is introduced via ortholithiation [9, 10] or lithium-halogen exchange as the first step [10][11][12] in ligand synthesis. Alternatively, the phosphine moiety can be introduced by nucleophilic substitution using an ortho-fluorophenyloxazoline as precursor (Scheme 29.1, route c) [13].…”

Section: Introductionmentioning

confidence: 99%

P,N and Non‐Phosphorus Ligands

Pfaltz¹,

Bell²

2006

The Handbook of Homogeneous Hydrogenation

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P,N and Non-Phosphorus Ligands Oxazoline-Derived P,N LigandsThe Crabtree catalyst ([Ir(PCy 3 )(py)(COD)]PF 6 ) [6] shows remarkable activity in the hydrogenation of alkenes, particularly sterically hindered tri-and even tetrasubstituted alkenes. Its structure has inspired a great deal of research into chiral P,N ligands for enantioselective hydrogenation, producing a variety of useful catalysts. The largest and most successful group of chiral analogues of the Crabtree catalyst are iridium complexes with oxazoline-derived P,N ligands.The oxazoline-derived P,N ligands can be classified into four groups according to structure: phosphino-oxazolines; phosphite-and phosphinite-oxazolines; catalysts containing a P-N bond; and structurally related non-oxazoline catalysts. Phosphino-oxazolines

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Preparation of novel Sulfur and phosphorus containing oxazolines as ligands for asymmetric catalysis

Cited by 89 publications

References 27 publications

Oxidative Addition of Palladium(0) Complexes Generated from [Pd(dba)2] and P-N Ligands: A Kinetic Investigation

Oxidative Addition of Palladium(0) Complexes Generated from [Pd(dba)2] and P-N Ligands: A Kinetic Investigation

Nickel(II) complexes bearing phosphinooxazoline ligands: Synthesis, structures and their ethylene oligomerization behaviors

P,N and Non‐Phosphorus Ligands

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