A convenient synthesis of pyrandione derivatives using P-toluenesulfonic acid as catalyst under ultrasound irradiation

Abstract

A new series of 3,3'-{alkane-α,ω-diylbis[imino-eth-1-yl-1-ylidene]}bis(6-methyl-2H-pyran-2,4(3H)-dione) derivatives (3c-e) has been synthesized by the convenient ultrasound-mediated condensation of a diamine with dehydroacetic acid in the presence of a catalytic amount of p-toluenesulfonic acid. The structure of all synthesized compounds was elucidated by IR spectroscopy, ¹H NMR spectroscopic spectra, elemental analysis, and mass spectroscopy. A tautomeric form for the derivatives species is also proposed.

Keywords: Dehydroacetic acid; Schiff base; Condensation; Catalyst; Ultrasound irradiation; Tautomerism