Diphosphine oxazoline ferrocenyl

Excellent enantioselectivity and double-bond regioselectivity can be achieved in an asymmetric Heck reaction between 2,3-dihydrofuran and aryl triflates by using a combination of chiral diphosphine-oxazoline ferrocenyl ligand and Pd catalyst <03CEJ3073>, as shown below. Chiral diphosphine-containing (arene)tricarbonylchromium(O) complexes were also used as ligands for this reaction to obtain the 2,3-isomer, however, both the yield and enantioselectivity were modest <03TA1455>. 

Scheme 11.16 Possible binding modes of the diphosphine oxazoline ferrocenyl ligands 31.

Tu, T., Deng, W.-R, Hou, X.-L. et al. (2003) The regioselectivity of the asymmetric intermolecular Heck reaction with planar chiral diphosphine-oxazoline ferrocenyl ligands. Chem. Eur. J., 9, 3073 1. 

Tu T, Hou X-L, Dai L-X (2003) Highly regio- and enantioselective Heck reaction of JV-methoxycarbonyl-2-pyrroline with planar chiral diphosphine-oxazoline ferrocenyl ligands. Org Lett 5 3651-3653... 

Figure 11.1 Comparison of bite angles of diphosphine ferrocenyl oxazoline with dppf and BINAP.

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