Method of preparing pyridazinone derivatives
CA 2065333 C · Owner: Howarth, Michael Scott · Inventors: Cox, Brian Geoffrey; Howarth, Michael Scott
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method for the preparation of a pyridazinone derivative having general formula (I), where: R1 is a phenyl group optionally substituted, R2 is H, alkyl or carboxy R3 is H, alkyl or alkoxy , and R4 is alkyl; said method comprising reacting a hydrazone of glyoxylic acid halide having formula (VII) in which X is halogen with an ester of formula (VIII) in the presence of an alkaline earth base.
Read the whole patent
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 August 29, 1990 and granted January 16, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 29, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 29, 2012.
- 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
Timeline From CIPO dates
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.