A novel asymmetric synthesis of r and s warfarin and its analogs
CA 2226752 C · Owner: The Dupont Merck Pharmaceutical Company · Inventors: Li, Hui-Yin; Robinson, Andrea Jane
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention provides a novel process for making compounds of formula (2a or 2b) or pharmaceutically acceptable salts thereof, wherein R1 is selected from the group consisting of phenyl and phenyl substituted with at least one group selected from NO2 and halogen, R2 is H; R3 is selected from the group consisting of C1-4 alkyl phenyl, and benzyl; and, R4 is selected from the group consisting of H and halogen; which comprises the steps of: a) oxidizing a racemate of formula (2) or a salt thereof to form a dehydro-compound of formula (3), wherein R5 is selected from the group consisting of H CH3, benzyl, C2-8 acyl, Na, Li and K; and b) asymmetrically, hydrogenating a compound of …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed July 10, 1996 and granted February 19, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 10, 2016.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 10, 2018.
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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.