Combining a Click–Multicomponent Reaction: One-Pot Synthesis of 1,2,3-Triazol-4-ylmethyl 3-Amino-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carboxylate Derivatives

Abstract

(1,2,3-Triazol-4-yl)methyl-3-amino-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carboxylate derivatives were synthesized by a four-component, one-pot condensation reaction of benzaldehyde derivatives, an active methylene compound (prop-2-ynyl-2-cyanoacetate), azides, and phthalhydrazide in the presence of Cu(OAc)₂/sodium ascorbate as catalysts and 1-methyl-1H-imidazolium trifluoroacetate ([Hmim]TFA) as an ionic liquid medium in good to excellent yields.

GRAPHICAL ABSTRACT

Keywords:

• 1,3-Dipolar cycloaddition
• multicomponent reaction
• pyrazolo[1,2-b]phthalazine-2-carboxylate derivatives
• 1,2,3-triazoles

Notes

^a Reaction conditions: 4-chlorobenzaldehyde 1a (0.14 g, 1 mmol), 1-azido-3-nitrobenzene 2a (0.16 g, 1 mmol), prop-2-ynyl 2-cyanoacetate 3 (0.14 g, 1.2 mmol), phthalhydrazide 4 (0.16 g, 1 mmol), Cu(OAC)₂ (0.02 g, 10 mol%), sodium ascorbate (0.04 g, 20 mol%), solvent (10 mL), 4 h.

^b Cu(OAC)₂ (0.02 g, 10 mol%), sodium ascorbate (0.04 g, 20 mol%), and p-TSA (0.34 g, 20 mol%).

^c Cu(OAC)₂ (0.02 g, 10 mol%), sodium ascorbate (0.04 g, 20 mol%), and [Hmim]TFA (10 mol%).

^d CuI (0.019 g, 10 mol%) and [Hmim]TFA (10 mol%).

^e CuSO₄ (0.016 g, 10 mol%), sodium ascorbate (0.04 g, 20 mol%), and [Hmim]TFA (10 mol%).

^f CuCl₂ (0.013 g, 10 mol%), sodium ascorbate (0.04 g, 20 mol%), and [Hmim]TFA (10 mol%).

^g Cu(OAC)₂ (0.01 g, 5 mol%), sodium ascorbate (0.02 g, 10 mol%), and [Hmim]TFA (10 mol%).

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