Carbon-13 NMR Spectra of 4-Chromanone, 4H-1-Benzothiopyran-4-one, 4H-1-Benzothiopyran-4-one 1,1-Dioxide, and Their Substituted Homologs

Abstract
The 13C NMR spectra of 4-chromanone, 4H-1-benzothiopyran-4-one, 4H-1-benzothiopyran-4-one 1,1-dioxide, and their methyl and phenyl substituted homologs were examined. The salient effect depending on the kinds of the hetero atoms or the group at the 1-position has been observed on the chemical shifts, especially for C-2, C-3, C-8, C-4a, and C-8a.