Bi Metal–Organic Framework (Ce/Ni–BTC) as Heterogeneous Catalyst for the Green Synthesis of Substituted Chromeno[4, 3–b]quinolone under Solvent Free Condition
Authors: Sayahi Mohammad Hosein , Yadollahi Mahtab , Hamad Samir M. , Ganjali Mohammad Reza , Aghazadeh Mustafa , Mahdavi Mohammad , Bahadorikhalili Saeed 
Published: January 2021

Aims :

Novel bi metal organic framework (b–MOF) is synthesized and used as a heterogeneous catalyst
for the synthesis of chromeno[4, 3–b]quinolone derivatives via one-pot and solvent-free, four-component reaction
of dimedone, aromatic aldehydes, 4–hydroxycoumarin and ammonium acetate at 110°C.

Background:

b–MOFs can be used as a heterogeneous catalyst in the synthesis of many organic compounds. The
active and multi-purpose sites in b–MOFs provide a varied function in their catalytic applications. In this paper,
reductive CES method is applied for the synthesis of Ce0.47/Ni0.53–BTC b–MOF. The resulting b–MOF was used
as a heterogeneous catalyst for the synthesis of chromeno[4, 3–b]quinolone via one-pot and solvent-free, fourcomponent
reaction of dimedone, aromatic aldehyde, 4–hydroxycoumarin and ammonium acetate at 110 °C.

Methods:

Ce0.47/Ni0.53–BTC was synthesized in an electrochemical cell composed of a stainless steel foil with a
size of 5cm×5cm centered between two 5cm×5cm sized graphite plates as the anodes by the cathodic current
density of 0.2 A/dm2 and placed in a solution of cerium nitrate (0.3 g), nickel nitrate (0.3 g), H3BTC (0.2 g) and
NaNO3 (0.1 g) in ethanol (500 mL). Ce0.47/Ni0.53–BTC (10 mg) was added to a mixture of dimedone (1 mmol),
aromatic aldehyde (1 mmol), hydroxycoumarin (1 mmol) and ammonium acetate (1.5 mmol) and stirred at 110
°C under solvent-free conditions for 45 min. The reaction evolution was controlled by the TLC (hexane:ethyl acetate,
4:1). Then, boiling ethanol was added to the reaction mixture and stirred at room temperature for 15 min.
After the reaction completion, the catalyst was separated by centrifuge. Finally, the reaction mixture was placed
in an ice bath, which resulted in a white solid product and recrystallized from ethanol to give the pure product.

Result:

The b–MOF catalyst showed very good efficiency in the synthesis of the desired compounds and can be
easily recovered by centrifuge and reused at least five times without a decrease in catalytic activity.

Conclusion:

In this report, a novel bi metal-organic framework (Ce0.47/Ni0.53–BTC) is synthesized via the cathodic
electrosynthesis method. The synthesized b–MOF is fully characterized by several characterization methods.
The catalytic activity of Ce0.47/Ni0.53–BTC is investigated in the synthesis of chromeno[4, 3–b]quinolone
derivatives via one-pot four-component reaction of dimedone, aromatic aldehyde, 4–hydroxycoumarin and ammonium
acetate. The reaction optimization results showed that the highest isolated yield was obtained when the
reaction was performed in solvent-free conditions at 110 °C. The catalyst showed to be highly efficient in the
synthesis of the desired compounds and performing the reaction utilizing various starting materials gave the
products in good isolated yields, which proves the generality and the scope of the method. The catalyst could easily
be recovered by centrifuge and reused at least five times without a decrease in catalytic activity.