1,4-Diazabicyclo[2.2.2]octane as an Efficient Catalyst for a Clean, One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives via Multicomponent Reaction in Aqueous Media

Abstract

1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as a mild and efficient catalyst for the synthesis of various tetrahydrobenzo[b]pyran derivatives via a one-pot, three component condensation of aromatic aldehydes, dimedone, and active methylene compounds. This method provides several advantages: a simple workup procedure, environmental friendliness, neutral conditions, and good yields. In addition, water or 50% aqueous ethanol was chosen as a green solvent.

Graphical Abstract

Keywords:

• Active methylene compound
• aromatic aldehyde
• dimedone
• multicomponent reaction
• tetrahydrobenzo[b]pyran

ACKNOWLEDGMENT

This work was supported by an Indiana University–Purdue University Fort Wayne Summer Faculty Research Grant.

Notes

^aAll reactions were run with 4-methylbenzaldehyde (2 mmol), dimedone (2 mmol), and malononitrile (2 mmol) in water refluxed for 2 h to afford compound 4j.

^bIsolated yields.

^aRefluxed in water for 2 h in the presence of 10 mol% DABCO as the catalyst.

^bRefluxed in 50% aqueous ethanol for 2 h in the presence of 10 mol% DABCO as the catalyst.

^cIsolated yields.