RECYCLIZATION OF 2-(3,6-DIARYL-2,5-DIHYDROPYRIDAZIN-4-YL)-1H-BENZIMIDAZOLES TO 2-[(3,5-DIARYLPYRAZOL-4-YL)METHYL]-1H-BENZIMIDAZOLES

摘要

2-(3,6-Diaryl-2,5-dihydropyridazin-4-yl)-1H-benzimidazoles undergo a previously unknown type of recyclization of the pyridazine ring to a pyrazole to give 2-[(3,5-diarylpyrazol-4-yl)methyl]-1H-benzimidazoles. It is suggested that the mechanism of this conversion, which includes formation of a secondary enhydrazine group in the diazine ring and its subsequent contraction, occurs after the intramolecular formation and opening of a cyclopropane ring.