Background: The pyridinium based p-toluenesulfonic acid functionalized [Py(CH2)4
SO3H][CH3PhSO3] ionic liquid has been employed as eco‐friendly solvent cum promoter for the
multicomponent domino heterocyclization of substituted 2-aminobenzothiazoles with 4-hydroxy-6-
methyl-2-pyrone / 4-hydroxycoumarin and aryl aldehydes to produce benzothiazolo[2,3-b]pyrano
[3,4-e]pyrimidin-4-ones and benzothiazole [2,3-b]chromeno[3,4-e]pyrimidin-6-one in excellent
Methods and results: Three-component synthesis of structurally diverse benzothiazolopyrano/
chromenopyrimidines, incorporating the privileged heterocyclic scaffolds of medicinal relevance has
been carried out by the reaction of substituted 2-aminobenzothiazoles with 4-hydroxy-6-methyl-2-
pyrone / 4-hydroxycoumarin and aryl aldehydes in pyridinium based p-toluenesulfonic acid functionalized
ionic liquid. The Brønsted acidic ionic liquid could be reused five-times without a significant
loss of catalytic activity.
Conclusion: The protocol proves to be efficient and facile in terms of high yields, operational simplicity,
reduced reaction time and ease of recovery of the reaction medium.