An Efficient and Sustainable Protocol for the Synthesis of Poly-Functionalized-Pyran Derivatives under Ultrasound Irradiation

Abstract

A highly efficient and catalyst-free green synthetic protocol is developed for the synthesis of two series of poly-functionalized pyran derivatives via the one-pot reaction of aromatic aldehydes, malononitrile, and either dimedone or 1,3-dimethyl barbituric acid with EtOH: H₂O (1:1 v/v) as solvent under ultrasound irradiation. Excellent yields (90–99%) of desired pyran derivatives were obtained for rapid reaction time 5 min. The structural features of the synthesized compounds were fully characterized by spectroscopic techniques (IR, HRMS ¹H, and ¹³C NMR). A simple workup, clean reaction profile, short reaction times, excellent yields, 95% atom economy, and 100% carbon efficiency are the benefits of the proposed protocol. In addition, the circumvention of the chromatographic separations is the further advantage of the procedure.

Graphical Abstract

Keywords:

• Green protocol
• multicomponent synthesis
• one-pot reaction
• poly-functionalized pyrans
• ultrasound irradiation

Additional information

Funding

The authors thank the National Research Foundation (NRF) of South Africa for the financial support, and the University of KwaZulu-Natal for research facilities. This study was funded by National Research Foundation (NRF) of South Africa.