Photoisomerization of cis,cis- and cis,trans-1,4-di-o-tolyl-1,3-butadiene in glassy media at 77 K: One-bond-twist and bicycle-pedal mechanisms

Abstract

(Chemical Equation Presented) Let's twist again: In the isomerization of cis,cis-1,4-di-o-tolyl-1,3-butadiene in isopentane glass at 77 K, hula-twist pathways are eliminated, because unstable photoproduct conformers do not form. Instead, the isomerization is found to proceed by bicycle-pedal (BP) and one-bond-twist (OBT) mechanisms (see scheme). © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.