Synthesis of p-coumaroylquinic acids and analysis of their interconversion

The synthesis of four isomers of p-coumaroylquinic acids was performed by esterification of p-acetylcoumaroylchloride with a suitably protected (-)-quinic acid. All isomers have been characterized by means of NMR spectroscopy and circular dichroism. Acyl migration was observed in the synthesis of 3-0-p-coumaroylquinic acid and 4-O-p-coumaroylquinic acid. Calculations on the most stable conformations of all isomers have also been performed to explain the acyl migration observed during the synthesis procedure.