Convenient Approach for the One-Pot, Three-Component Synthesis of Triheterocyclic 4H-Pyrimido[2,1-b]benzothiazole Derivatives Using TBAHS

Abstract

An efficient and convenient synthesis of 4H-pyrimido[2,1-b]benzothiazole derivatives has been achieved by a one-pot, three-component condensation reaction of 2-aminobenzothiazole (1) with substituted benzaldehydes (2a–f) and β-dicarbonyl derivatives (3a–e) in presence of 30 mol% of tetrabutylammonium hydrogen sulfate (TBAHS) in good to excellent yields.

GRAPHICAL ABSTRACT

Keywords:

• Multicomponent condensation
• pyrimidobenzothaizole
• tetrabutylammonium hydrogen sulfate (TBAHS)

ACKNOWLEDGMENTS

The authors are thankful to the director, IICT, and head, Organic Chemistry Division II, Indian Institude of Chemical Technology, for their constant encouragement and support. Hanmant K. Gaikwad thanks the University Grants Commission, New Delhi, for the award of a research fellowship.

Notes

^a Isolated yields obtained after column chromatography.

^b No reaction.

^a Reaction conditions: 1 (1 mmol), 2a (2 mmol), 3a–e (2 mmol), TBAHS (30 mol %), 120 °C, and ethylene glycol (5 mL).

^b Isolated yields obtained after column chromatography.

^a Reaction conditions: 1 (1 mmol), 2b–f (2 mmol), 3a (2 mmol), TBAHS (30 mol %), 120 °C, and ethylene glycol (5 mL).

^b Isolated yields obtained after column chromatography.