In the former, the charge serves only to accelerate appreciably thermal orbital‐symmetry allowed reactions, whereas in the latter, the charge determines the course of the transformations accordoi:10.1002/HLCA.19730560104U. WidmerJ. ZsindelyHans‐Jürgen HansenHans Schmidhelvetica chimica acta...
Abstract The recent synthesis of enantiomerically pure (−)-( M )- σ -[4]helicene has provided an archetype helical model system for vibrational optical activity, comparable to what π -helicenes represent in the field of electronic optical activity. We present the first measurements and the ...