Orion-yhtyma Oy

Jorma V Haarala

Erkki J Honkanen

Heimo O Haikala

Pentti T Nore

Tom Wikberg

Reijo J Backstrom

Aino K Pippuri

Reijo B Ackstr Om

The compound (-)-[[4-(1,4,5,6 tetrahydro-4-methyl-6-oxo-3 pyridazinyl) phenyl]-hydrazono] propane dinitrile and its salts are prepared and used for treating congestive heart failure.

(-)-[[4-(1,4,5,6-tetrahydro-4-m

Diastereomeric intermediate salts of formulae (IIIa) or (IIIb) ##STR1## are prepared.

Stable and crystallographically essentially pure polymorphic form A of (E)-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitro-phenyl)acrylamide may be prepared by crystallizing crude synthesis product from lower aliphatic carboxylic acid such as formic or acetic acid with a catalytic amount of hydrochloric or hydrobromic acid added. The product is a potent inhibitor of catechol-O-methyl-transferase enzyme (COMT).

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Jorma V Haarala