SiO₂-BiCl₃ as Heterogeneous Catalyzed Synthesis of 6-Methyl-2-aryl-4,5-dihydropyridazin-3(2H)-one Derivatives

Abstract

A mild and highly efficient stereoselective reaction using silica supported bismuth(III) chloride (SiO₂-BiCl₃) has been successfully employed in the synthesis of 6-methyl-2-aryl-4, 5-dihydropyridazin-3(2H)-one derivatives (3a-o) with a variety of phenyl hydrazines (1a-o) bearing either electron withdrawing or donating functional groups and 4-pentynoic acid (2). The catalyzed reaction proceeded smoothly under room temperature in THF to give the corresponding 3a-o derivatives in good to excellent yields. The 3a-o derivatives have been characterized by IR, ¹H NMR, ¹³C NMR, mass and elemental analysis. The use of this approach allowed us to rapidly screen a selection of conditions and quickly confirm the viability of preparing the target 3a-o derivatives in short reaction times.

Keywords:

• Hydrohydrazination
• phenyl hydrazine
• pyridazinone
• 4-pentynoic acid