C-13 NUCLEAR MAGNETIC-RESONANCE STUDY OF BENZO[B]THIOPHENES AND BENZO[B]THIOPHENE S-OXIDES AND S,S,-DIOXIDES

The 13C NMR spectra of benzo[b]thiophenes and a series of benzo[b]thiophene S-oxides and S, S-dioxides of well-defined structure were recorded. A comparison between benzothiophenes and the sulfoxide and sulfone derivatives permits the characterization of the effect of the sulfoxide and sulfone moieties on 13C chemical shifts in this heteroaromatic system. A comparison of the 13C resonances of benzothiophene S-oxides and S, S-dioxides with the corresponding derivatives of 2, 3-dihydrobenzothiophene shows a decrease in aromaticity on going from the benzo[b] thiophene to the S-oxide and S, S-dioxide systems, the sulfoxide being more aromatic than the sulfone. © 1979, American Chemical Society. All rights reserved.