Immobilization of 1,4-Diazabicyclo[2.2.2]Octane (DABCO) over Mesoporous Silica SBA-15: An Efficient Approach for the Synthesis of Functionalized Spirochromenes

Abstract

Immobilized 1,4-diazabicyclo[2.2.2]octane (DABCO) over mesoporous silica SBA-15 has been found to be an efficient heterogeneous base catalyst for the synthesis of biologically active functionalized spirochromene derivatives via three-component reaction of isatins/acenaphthoquinone, activated methylene reagents, and 1,3-dicarbonyl compounds in aqueous media. This ecofriendly protocol offers several advantages such as a cost-effective procedure with excellent yield, short reaction time, simple workup, recovery and reusability of catalyst, good functional group tolerance, and broad scope of usable substrates.

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GRAPHICAL ABSTRACT

Keywords:

• Heterogeneous catalyst
• mesoporous SBA-15
• multi-component reaction
• spirochromenes

ACKNOWLEDGMENT

We are thankful to the Research Council of Mazandaran University for the partial support of this work.

Notes

^a Yields refer to isolated products.

^b 10 wt% of isatin.

^a At rt

^b At 50 °C.

^c Yields refer to isolated products.

^a Reaction conditions: acenaphthoquinone (1 mmol); activated methylene reagents (1 mmol); 1,3-dicarbonyl compounds (1 mmol); catalyst: SBA-15–DABCO (7 mol%); solvent: H₂O (5 mL); temperature: 50 °C.

^b Yields refer to isolated products.