循環器系薬の合成研究(第3報)Pyrano[2,3-c]pyrazolone誘導体の合成

概要

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Synthetic studies on pyrano [2,3-c] pyrazolones were planned to find new cardiovascular drugs. A mixture of α-acetyl-γ-butyrolactone (ABL) and 3-methyl-2-pyrazolin-5-one (I_1) was heated to give α-[1-(3-methyl-5-oxo-2-pyrazolin-4-yl)ethylidene]-γ-butyrolactone (II_1). However, the desired ring closure product, 5-(2-hydroxyethyl)-3,4-dimethyl pyrano-[2,3-c] pyrazol-6(1H)-one (III_1) was easily obtained under reflux in dimethylformamide (DMF). 5-Aminoethyl derivatives (IV) were produced from III in the usual manner. It was found that substitution reactions of pyrano [2,3-c] pyrazoles with alkyl halides usually took place at the position 2 in preference to position 1. A novel ring opening-reclosure occurred in the reaction of 3,4-dimethyl-1-(2-tosyloxyethyl) pyrano [2,3-c] pyrazol-6(1H)-one (XXIII) with the appropriate amine to afford new pyrazolo [3,2-b] [1,3] oxazole compounds. In these compounds, pyrano [2,3-c] pyrazolones possessing N-substituted phenylpiperazine moiety showed coronary vasodilating and antihypertensive activities.
社団法人日本薬学会の論文
1978-03-25