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US 7,582,763 B2Granted
Enantioselective process
AssigneeSchering Corporation
InventorsFrank Xing Chen, Yee-Shing Wong, Feng Liang, Marc Poirier, George Wu
Life of this patent
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Abstract
An enantioselective process for preparing intermediates useful in the preparation of the chiral tricyclic compound of formula I is disclosed.
Claims4
A process for the preparation of a compound represented by formula V
- which comprises (1) contacting a compound represented by formula IIA
- with at least about an equivalent amount of phosphorous acid in the presence of catalytic amount of an alkali iodide or iodine and hydrobromic acid in water to form a reaction mixture, and then adding to the reaction mixture at least about an equivalent of hypophosphorous acid to form a compound represented by formula IIIA
- (2) contacting the resulting compound represented by formula IIIA with at least about an equivalent amount of bromine in the presence of an organic acid and a lower alkanol to form a compound represented by formula IVA
A process of preparing compounds represented by formulas IVA and IVB
- which comprises contacting compounds represented by formulas IIA and IIB
- with at least about an equivalent amount of phosphorous acid in the presence of at least a catalytic amount of sodium iodide, hydrobromic acid, in water to form a reaction mixture and adding to the so-formed reaction mixture at least about an equivalent amount of hypophosphorous acid, and continuing the contacting for a time sufficient to form a reaction mixture comprising the compounds represented by formulas IIIA and IIIB, and contacting the resulting reaction mixture with at least about an equivalent of bromine in the presence of an organic acid and a lower alkanol to form a compound represented by formula form a mixture comprising the compounds represented by formulas IVA and IVB.
Dependencies are inferred from the claim text.