Studies on Pyridazines. XX. Syntheses of 1, 2-Bis (3'-pyridazinyl)-ethenes, -ethanes, and Their Di-N-oxides

Abstract

The compounds, in which two pyridazine rings are combined through two carbon atoms, were synthesized. 3-Methylpyridazine 2-oxide (I) was condensed with 3-formylpyridazine 2-oxide (II) to give 1, 2-bis [3'-(2'-oxido)-pyridazinyl]- ethene (III). Reaction of III with PCl₃ in CHCl₃ afforded the deoxygenated compound, 1, 2-bis (3'-pyridazinyl)-ethene (IV). Oxidation of IV with H₂O₂ in AcOH gave 1'1'-di-N-oxide (V). Catalytic hydrogenation of III with Pd-C afforded 1, 2-bis (3'-pyridazinyl)-ethane (VI). Oxidation of VI afforded three kinds of di-N-oxides, i.e., 1', 1'-di-N-oxide (VII), 1', 2'-di-N-oxide (VIII), and 2', 2'-di-N-oxide (IX). Wurtz's reaction of chloromethylpyridazines was also carried out, affording the corresponding ethane (XI) and ethene (XII) derivatives.