Metal asymmetric Heck reaction

A novel phosphinito dipeptido ligand series were prepared, and fully characterized. These ligands readily form metal complexes with Pd(H) and Pt(II) precursors. The Pd(II) complexes were investigated for their suitability in asymmetric Heck reaction using 3,4-dihydrofuran as a substrate. 

For intermolecular asymmetric Heck reaction between aryl triflates and 2,3-dihydrofuran the hindered diphosphine 1 is superior to BINAP. Improved enantioselectivity is due to the bulky f-butyl substituents to create a more ideal chiral pocket in the metal complexes. 

Metal-Catalyzed Cross-Coupling Reactions, Vol. 1,2nd edn (eds A. de Meijere and F. Diederich), Wiley-VCH Verlag GmbH, Weinheim, Germany, pp. 217-315 (c) Dounay, A.B. and Overman, L.E. (2003) The asymmetric intramolecular Heck reaction in natural product total synthesis. Chem. Rev., 103, 2945-63 (d) Link, J.T. (2002) The intramolecular Heck reaction. Org. React., 60, 157-534 (e) Shibasaki, M. and Miyazaki, F. (2002) Asymmetric Heck reactions, in... 

Dodd, D.W., Toews, H.E., Carneiro, RD.S. et al. (2006) Synthesis of metal complexes of peptide-phosphinites metal complexes in asymmetric Heck reaction. Inorg. Chim. Acta, 359, 3054-65. 

Keywords Allylic Alkylation m Asymmetric Catalysis m C2-Symmetry m De-symmetrization m Electronic Differentiation m Heck Reaction m Hydrogenations m Metal Complexes m Modular Design m P,N-Ligands m Steric Differentiation m Respective Control... 

Another significant development in oxazoline chemistry is the application of oxazoline-containing ligands for asymmetric catalysis, such as palladium-catalyzed allylic substimtions, Heck reactions, hydrogenations, dialkylzinc additions to aldehydes, and Michael reactions. The discovery of diastereoselective metalation of chiral ferrocenyloxazolines has further expanded the availability of chiral ligands for metal-catalytic reactions. 

One of the emerging applications of 4,5-dihydroimidazole-based compounds is as chiral auxiliaries in metal complexes used for asymmetric synthesis for example, 457 in ruthenium-catalyzed DielsAlder reactions <2001 J(P 1)1500, 2006JOM(691)3445> 458 in diethylzinc addition to aldehydes <2003SL102> 459 in asymmetric intramolecular Heck reactions <20030L595> and 460 in ruthenium-catalyzed epoxidation <2005OL3393> and iridium-catalyzed hydrogenation of imines <2004TA3365>. 

A wide variety of synthetic processes have been rendered asymmetric through the use of a chiral catalyst. In addition to the types of reaction described above, chiral transition metal catalysts have been used to influence the stereochemical course of isomerization, cyclization, and coupling reactions. As an example, an approach towards the natural product (-)-epibatidine (158) was recently reported by Namyslo and Kaufmann (166). Epibatidine is a potent analgesic and a nicotinic receptor agonist. The synthesis involves an asymmetric Heck-type hydroarylation between the bicyclic alkene (155) and pyridyl iodide (156). A number of bidentate chiral li-... 

Prior chapters have covered the use of transition metals in asymmetric hydrogenations ( 6.2 and 7.1), hydroborations ( 7.3), hydrosilylations and hydro-cyanations ( 6.3, 6.4, 7.4 and 7.5), cyclopropanations ( 7.19), aldol reactions ( 6.11), allylations of carbanions ( 5.3.2), and some sigmatropic rearrangements ( 10.3). This chapter covers other reactions catalyzed by transition metal complexes including coupling of organometallic reagents with vinyl, aryl or allyl derivatives, Heck reactions allylamine isomerizations, some allylation reactions, car-bene insertions into C-H bonds and Pauson-Khand reactions. 

The enantioselective spiro ring construction is an important issue because many natural compounds have chiral spiro centers [103,104]. Pd catalyses of Spiro cyclizations have been reported by asymmetric intramolecular Mizoroki-Heck reactions [105,106]. In spite of a similar potential, transition metal-catalyzed ene-type carbocyclization has never been applied to asymmetric spiro cyclizations [107-110]. 

Water-soluble macromolecular metal complexes based on terminally functionalized ethylene oxides and ethylene oxide-propylene oxide block copolymers have been used as catalysts for hydroformylation, hydrogenation, Wacker oxidation of imsaturated compounds, hydroxylation of aromatic compounds, oxidation of saturated and alkylaromatic hydrocarbons, metathesis, Heck reaction, and some asymmetric reactions. 

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