Stereoselective hetero-Diels-Alder reactions: structure determination of new xanthenedione derivatives by NMR spectroscopy and x-ray crystallography

Abstract

The proton and carbon spectra of chromane derivatives were completely assigned by the use of 1H, 13C and 2D NMR spectroscopy, including NOESY and 2D INADEQUATE. The unambiguous configurational assignments of all regioisomers were achieved via 2D NOESY. The structure of the regioisomer 7A was confirmed using x‐ray diffraction. © 1999 John Wiley & Sons, Ltd.