2-Alkylidene-4H-3,1-benzoxathiin-4-ones were efficiently synthesized by reaction of 2-(acylthio)benzoic acids with condensation reagents in the presence of base. The E and Z isomers of the products were distinguished by comparison of the chemical shifts of the vinylic protons in the H-1 NMR spectra of the 4H-3,1-benzoxathiin-4-ones and their corresponding 1-oxides.
2-Alkylidene-4H-3,1-benzoxathiin-4-ones were efficiently synthesized by reaction of 2-(acylthio)benzoic acids with condensation reagents in the presence of base. The E and Z isomers of the products were distinguished by comparison of the chemical shifts of the vinylic protons in the H-1 NMR spectra of the 4H-3,1-benzoxathiin-4-ones and their corresponding 1-oxides.
2-Alkylidene-4H-3,1-benzoxathiin-4-ones were efficiently synthesized by reaction of 2-(acylthio)benzoic acids with condensation reagents in the presence of base. The E and Z isomers of the products were distinguished by comparison of the chemical shifts of the vinylic protons in the H-1 NMR spectra of the 4H-3,1-benzoxathiin-4-ones and their corresponding 1-oxides.