Synthesis and structure of (R,S)-2-methyl-4-(4-nitrophenyl)-pyrano[3,2-c]chromen-5(4H)-one

In this paper, the synthesis and structure of a novel pyrano[3,2-c]coumarin, which was obtained unexpectedly in a reaction of phosphoryl chloride and acenocoumarol, are presented. The chemical structure of the novel compound was elucidated by a detailed spectroscopic analysis based mainly on 1D and 2D NMR techniques. The structure was finally confirmed with a single-crystal X-ray analysis. The B3LYP/6-311+G** method correctly reproduces the bond lengths, bond angles, torsion angles, and other experimental spectroscopic data, which can be useful for investigating the characteristics of some structurally related molecules. Additionally, the title compound was obtained in high yields by performing a dehydratation reaction of acenocuomarol with acetic anhydride.