Synthesis and '3C-NMR Spectra of Dimethyl-4-chromanones

Abstract

¹³C-NMR spectra of 2, 2- and 2, 3-dimethyl-4-chromanone derivatives have been examined. The latter was prepared from 2-methyl-2-butenoic acid and the corresponding phenols in the p r e s ence of polyphosphoric acid. The NMR signals were assigned by comparing the spectra of closely related compounds and on the basis of the comparison between the calculated an d observed chemical shift values for the aromatic ring carbons. The 3-methly carbon resonanc e at significantly high field (δ 9.4-10.5) in 2, 3-dimethy1-4-chromanones seems to be usefu for their conformational assignment.