Mitsubishi Chemical Industries Limited

Rikizo Furuya

Hiromi Okushima

Shinichiro Fujimori

Makio Kobayashi

Akihiro Narimatsu

Yoshimi Kitada

Shuzo Hayakawa

Issei Nitta

Piperazinyl carbonyl phenyl pyridazinone derivatives useful as

There are provided novel pyridazinone derivatives having the general formula (I): ##STR1## wherein A represents 5- or 6-membered heterocyclic ring having 1-3 nitrogen atoms, which may be substituted by at least one member selected from the group consisting of C.sub.1-5 alkyl, cyano, hydroxyl, C.sub.1-5 alkoxy, amino, C.sub.1-5 alkylamino, C.sub.2-6 dialkylamino, C.sub.2-5 acylamino, carboxyl, C.sub.2-5 alkoxycarbonyl and carbamoyl, and R.sup.1 and R.sup.2 independently represent hydrogen atom or C.sub.1-5 alkyl or R.sup.1 and R.sup.2 may form together C.sub.1-5 alkylene, and salts thereof.

Pyridazinone derivatives and salts thereof as cardiac stimulants

A 7.alpha.-acylthio-4-en-3-oxosteroid such as 7.alpha.-acetylthio-17-hydroxy-3-oxo-17.alpha.-pregn-4-ene-21-carboxylic acid .gamma.-lactone (spironolactone) which is an antialdosteronic diuretic effective in therapy is prepared by contacting a steroidal material which contains a 7.beta.-acylthio-4-en-3-oxosteroid with a thiocarboxylic acid.

Method for preparing 7.alpha.-acylthio-4-en-3-oxosteroids

An alkali metal salt of a 3-(17.beta.-hydroxyandrosten-3-one 3-acetal-17.alpha.-yl)propiolic acid which is useful as an intermediate in the preparation of 3-(3-oxo-7.alpha.-acetylthio-17.beta.-hydroxyandrost-4-en-17.alpha.-yl)-pr opiolactone (spironolactone) as antialdosteronic diuretics and hypotensive agents is prepared by reacting a 17.beta.-hydroxypregnen-20-yn-3-one 3-acetal (I) with an alkali metal dimsyl (II) to give an alkali metal salt of the 17.beta.-hydroxypregnen-20-yn-3-one 3-acetal (III), and reacting the compound (III) with carbon dioxide followed by hydrolysis.

Process for preparing steroid-carboxylates

A steroidal 7.alpha.-acylthio-4-en-3-one is produced by adding a thiocarboxylic acid to a steroidal 4,6-dien-3-one in the presence of a strong acid in a neutral organic solvent.

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Yokohama, Japan

Rikizo Furuya