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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


  • J.S. thanks the National Science Foundation (Grant No. CHE-0314784) for partial support of this research


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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).