(R/S)-Ethyl 2-Acetoxy-4-phenyl-4H-chromene-3-carboxylate

A simple protocol for the preparation of O-acylated enol form (R/S)-ethyl-2-acetoxy-4-phenyl-4H-chromene-3-carboxylate 5 was presented. The compound was characterized by H-1-, C-13-and DEPT135 NMR spectra, including {H-1,H-1} COSY, {H-1,C-13} HSQC, {H-1,C-13} HMBC, and 2D-NOESY spectra. The preferred regioselectivity for O-acylation of 3,4-dihydrocoumarin 5 in the presence of substituent in the 4th position in the chroman ring and accounting for the steric hindrance of the ester group in the 3rd place was confirmed.