Process for preparing ketone enantiomer
CA 2124454 C · Owner: Pfizer Inc. · Inventors: Quallich, George J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A novel multi-step process for preparing the (4S-enantiomer of 4-(3,4-dichlorophenyl)-3,4-dihydro-1(2H)-naphthalenone in a highly-optically pure form is disclosed. The process involves (1) first esterifying 4-(3,4-dichlorophenyl)-4-ketobutanoic acid with isopropylene or isobutylene to form the corresponding isopropyl or tert.-butyl 4-(3,4-dichlorophenyl)-4-ketobutanoate; (2) then reducing the ketobutanoic acid ester obtained in the first step with an asymmetric carbonyl reducing agent to form the corresponding chiral isopropyl or tert.-butyl 4-(3,4-dichlorophenyl)-(4R)-hydroxybutanoate; (3) then sulfonylating the (4R)-hydroxybutanoic acid ester with methanesulfonyl benzenesulfonyl or …
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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 September 15, 1992 and granted August 26, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 15, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 15, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.