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

A highly efficient and catalyst-free green synthetic protocol is developed for the synthesis of two series of poly-functionalized pyran derivativesviathe 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, (HRMSH)-H-1, and(13)C 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.

Automated summary

In this study, a highly efficient and catalyst-free green synthetic protocol was developed for the synthesis of two series of poly-functionalized pyran derivatives. The protocol showed excellent yields, simple workup, short reaction times, and high atom economy and carbon efficiency. The circumvention of chromatographic separations was also an advantage of this procedure.