Study of multicomponent synthesis of 7-alkyl or aryl-6H,7H-benzo[f]chromeno[4,3-b] chromen-6-ones involving N,N-disulfopiperidiniumbisulfate [DSPP][HSO4] as efficient recyclable homogeneous Brönsted acidic catalyst

Abstract

Herein, a new type of pyranocoumarin derivatives 7-alkyl or aryl-6H,7H-benzo[f]chromeno[4,3-b] chromen-6-ones (2a-h) was developed via three component reaction of 4-hydroxy coumarin, β-naphthol and aliphatic/aryl aldehydes using 25 mol% of N,N-disulfopiperidinium bisulfate [DSPP][HSO₄] as homogeneous recyclable Brönsted acidic ionic liquid catalyst in EtOAc under reflux to produce excellent yields (89-97%) of the products within 2-4 h reaction. In neat condition, the same reaction required 4.5 h to produce 90% yield of model product (2d) at 100 ℃, which took only 2.5 h to yield 97% of the same product in EtOAc under reflux temperature.

Keywords: Acidic ionic liquids; Homogeneous catalyst; Piperidinium; Pyranocoumarins; Recyclable; Three-component.