ChemInform Abstract: Reaction of Some 1,2-Diaza-1,3-butadienes with Activated Methine Compounds. A Straightforward Entry to 1,4-Diyhdropyridazine, Pyridazine, and 4,5(4H,5H)-Cyclopropylpyrazole Derivatives.

✍ Scribed by Orazio A. Attanasi; Paolino Filippone; Chiara Fiorucci; Elisabetta Foresti; Fabio Mantellini

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 41 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199922153

✦ Synopsis

Reaction of Some 1,2-Diaza-1,3-butadienes with Activated Methine Compounds.

A Straightforward Entry to 1,4-Diyhdropyridazine, Pyridazine, and 4,5(4H,5H)-Cyclopropylpyrazole Derivatives.

-Aminocarbonyl diaza compounds (I) give with different β-tri-or β-dicarbonyl compounds of type (II) and (V) 1,4-dihydropyridazines like (III). The latter compounds are conveniently converted to pyridazines by bromination with tribromide on Amberlyst A-26 as solid-phase brominating reagent followed by ready dehydrobromination. Compound (V) affords mixtures of dihydropyridazines (III) and (VI) in a similar ratio, probably because of the nearly equivalent possibility of ring closing on the two different keto groups. With phenoxy diketone (VIII) the pyridazines are formed directly with no evidence of dihydro intermediates. Surprisingly, the alkoxy derivatives of type (X) produce cyclopropapyrazoles (XIII). A detailed investigation of the reaction pathway demonstrates some interesting interconversions of these products to dihydropyridazines and finally to pyrroles.

-(ATTANASI, ORAZIO A.;