2,2′,6,6′-tetraoxazolinyl biphenyl ligand and...

Details 2,2′,6,6′-tetraoxazolinyl biphenyl ligand and... 2,2′,6,6′-tetraoxazolinyl biphenyl ligand and...

2006-12-29

2010-08-03

Saeed, Kamal A (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

active

07767825

ABSTRACT:
The present invention relates to a method for preparing 2,2′,6,6′-tetraoxazolinyl biphenyl ligand in chemical industry field. In the present invention, compound (III) is reacted with an activator that can activate the hydroxyl group selected from the group consisting of alkyl halosulfonium compound, aryl halosulfonium compound, phosphoryl chloride, phosphorus pentachloride, thionyl chloride and triphenyl phosphine, in the presence of alkali(s), to give the target product (IV), 2,2′,6,6′-tetraoxazolinyl biphenyl ligand. The ligand of the present invention can be used in various asymmetric reactions catalyzed by metals, with high reactivity and stereoselectivity, and thus represents a good application outlook. The 2,2′,6,6′-tetraoxazolinyl biphenyl ligand has the formula of:wherein, R1=hydrogen, alkyl, substituted or unsubstituted aryl, substituted or unsubstituted benzyl; R2=hydrogen, alkyl, substituted or unsubstituted aryl, substituted or unsubstituted benzyl; R3=hydrogen, alkyl, substituted or unsubstituted aryl, substituted or unsubstituted benzyl; R4=hydrogen, alkyl, substituted or unsubstituted aryl, substituted or unsubstituted benzyl.

REFERENCES:
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Gant T.G. et al, “The First Enantioselective Synthesis of the Chemotactic Factor Sirenin by an Intramolecular [2+1] Cyclization Using a New Chiral Catalyst”, Tetrahedron Letters, vol. 36, No. 48, pp. 8745-8748 (1995).
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Imai Y. et al., “Novel Axial Chiral Catalyst Derived from Biphenyl Ligand Bearing only Twoortho-Substituents”, Tetrahedron Letters, vol. 38, No. 15, pp. 2681-2684 (1997).
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U.S. Appl. No. 12/159,440 to Wanbin Zhang et al., filed Jun. 27, 2008.

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