Rate Acceleration of the Retro Diels-Alder Reaction of Anthracene Cycloadducts by Polysiloxy Substituents
Abstract:
The effects of diene substitution on the rate of the retro Diels- Alder reaction are not well understood. Siloxy substituents have, however, been shown to increase the rate of cycloreversion. In an effort to find cycloadditioncycloreversion systems that are relatively fast in both directions, polysiloxy anthracenes were synthesized. The Diels-Alder reactivityboth forward and retroof polysiloxyanthracenes with acrylonitrile was investigated and compared to that of nonsilylated anthracenes. The siloxy substituents slow the forward reaction moderately and accelerate the retro reaction significantly. The unexpected slowing of the forward reaction has been rationalized as being due to ring strain preventing complete conjugation of oxygen lone pairs. Theses Anthratenes.