Crystal X-ray diffraction guided NMR analysis of 3,9-diaryl-2,4,8,10-tetraoxaspiro[5.5]undecanes under differently shielding effect of terminal aromatic rings

The stereoscopic structures of 3,9-di(o-, m- and p-chlorophenyl)-2,4,8,10-tetraoxaspiro[5.5]undecanes were elucidated via high-resolution 1D and 2D NMR techniques including 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HSQC, and HMBC. Complete and accurate assignment of 1H and 13C spectral data, especially the discrimination of hydrogens and carbons in four methylenes under differently shielding effect of aromatic rings were achieved by NMR analysis guided by crystal X-ray diffraction.