An
efficient and chemodivergent synthesis of highly functionalized
1,4-dihydropyridazines and parazoles has been accomplished via base-promoted
annulation between hydrazones and alkyl 2-aroyl-1-chlorocyclopropanecarboxylates,
respectively. This transition-metal-free domino reaction proceeded
rapidly under mild basic conditions, affording potentially bioactive
1,4-dihydropyridazine and parazole derivatives in moderate yields.
The conversion of 1,4-dihydropyridazine to pyrazole was confirmed
by adjusting the quantity of the base.