The Clean and Mild Synthesis, Crystal Structure, and Intra-Molecular Hydrogen Bond Study of Substituted New 4,8-Dihydropyrano[3,2-B]-Pyrans Containing Chlorokojic Acid Moiety

Abstract

A safe, green and convenient process was developed for the synthesis of a novel group of 4,8-dihydropyrano[3,2-b]-pyrans by dialkyl acetylenedicarboxylates and alkyl isocyanides being trapped by chlorokojic acid in good to excellent yields at ambient temperature. Characterization of all structures was carried out by FT-IR and 1H and 13C NMR spectrometers, and two compounds were analyzed using X-ray diffraction technique. Crystal structures showed an intramolecular hydrogen bond and stacking of the dimeric (RS) molecules with the unit cell along the a-axis. © 2019, Springer Nature B.V.