“…In this respect, thiophene 1,1-dioxide units show much larger coupling constants (7-7.5 Hz) for the thiophene α,βprotons [62] than thiophene units itself (5.6-5.9 Hz). [40,63] Furthermore, in IR spectra of sulfones a characteristic symmetric stretching band arises in the regime of 1135-1170 cm À 1 , an asymmetric band between 1300-1335 cm À 1 . [64] In contrast, for aromatic N-oxides a stretching band in the regime of 1200-1300 cm À 1 is expected.…”