Process for producing pyrido[1,2-a] pyrimidine derivative
申请人:WAKO PURE CHEMICAL INDUSTRIES LTD
公开号:EP0385634A2
公开(公告)日:1990-09-05
3-Tetrazolylpyrido[1,2-a]pyrimidin-4-ones of formula
useful as an antiallergy agent are produced by reacting a cyano derivative of pyrido[1,2-a]pyrimidin-4-one 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.
Process for producing 3-tetrazolyl pyrido[1,2-a]pyrimidine derivatives
申请人:Wako Pure Chemical Industries, Ltd.
公开号:US05081243A1
公开(公告)日:1992-01-14
3-Tetrazolylpyrido[1,2-a]pyrimidin-4-one derivatives useful as an antiallergy agent are produced by reacting a cyano derivative of pyrido[1,2-a]pyrimidin-4-one 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.
A facile and practical synthesis of 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1, 2-α]pyrimidin-4-one (4), the potassium salt of which is used clinically as an anti-asthma agent, is described. Treatment of a key intermediate (6b), prepared from 2-amino-3-methylpyridine (1) and 2-ethoxymethylene-1, 3-propanedinitrile, with sodium azide in N, N-dimethylformamide gave predominantly the cyanotetrazole (7a), while in acetic acid it gave exclusively the iminotetrazole (7b), which was easily converted into 4 by acid hydrolysis. A one-pot process starting from 6b to give 4, avoiding the use of explosive aluminum azide, was established.