Process for producing pyrido1,2-apyrimidine derivative
CA 2010336 C · Owner: Ishihara, Masami · Inventors: Nawa, Hiroyoshi; Yoshihara, Jun; Ishihara, Masami
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
3-Tetrazolylpyrido1,2-apyrimidin-4-one derivatives useful as an antiallergy agent are produced by reacting a cyano derivative of pyrido1,2-apyrimidin-4one compound with (i) hydrazoic acid, followed by hydrolysis, or with (ii) a salt of hydrazoic acid reacting the resulting product with an acid or a base followed by hydrolysis.
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 February 19, 1990 and granted November 19, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 19, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 19, 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.