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Synfacts 2005(0): 0059-0059  
DOI: 10.1055/s-2005-869947
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Chiral Ferrocenyl Phosphine-Triazines as Ligands for Asymmetric Allylic Substitution

Rezensent(en): Mark Lautens, Andrew Martins
X.-P. Hu, H.-L. Chen, Z. Zheng*
Dalian Institute of Chemical Physics, P. R. China
Ferrocene-Based Chiral Phosphine-Triazines: A New Family of highly Efficient P,N Ligands for Asymmetric Catalysis
Adv. Synth. Catal.  2005,  347:  541-548  
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Publikationsdatum:
20. Juli 2005 (online)

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Key words

palladium(II) - allylic alkylation - allylic amination - triazines - ligands

Significance

Asymmetric allylic alkylations have been exhaustively studied, and excellent enantio­selectivities have been demonstrated in numerous cases. Ferrocenyl-based P,N-ligands have recently received attention, with the incorporation of N-heterocycles believed to influence selectivity. The pendant triazine was found to increase enantio­selectivity, with better selectivity than cases with less N content. Allylic substitution with malonates (α-substituted and unsubstituted) and benzyl­amine were demonstrated, displaying excellent yield and selectivity with malonates, and good yield and selectivity with amination.

Comment

The triazine ligand where R′ = Ph showed highest utility, providing the best combination of yield and enantioselectivity. For a similar approach employing N-heteroaryls towards Rh-catalyzed hydroboration, see: D. J. Connolly, P. M. Lacey, M. McCarthy, C. P. Saunders, A.-M. Carroll, R. Goddard, P. J. Guiry J. Org. Chem. 2004, 69, 6572-6589.

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