Forbidden 1,3-sigmatropic rearrangements

Application of the Cplex-isoelectronic theory to electrocyclisations, sigmatropic rearrangements, cheletropic reactions and antiaromaticityConsistent with Santilli's hadronic chemistry

“…In the case of the bicyclo[4.2.0]octene system 19 (Fig. 10), the rate of the retention pathway is greater that the inversion pathway and the retention pathway is more stereospecific [37]. These empirical results are consistent with the existence of a concerted process for both the inversion and retention products and thus consistent with the existence of the analogous electronic mechanism 15.…”

“…The kinetics of the bicyclo[3.2.0]hept-2-ene system 18 (Fig. 10), shows that retention and inversion occurred with only a factor of 7 between them [37]. Furthermore the stereospecificity factor (inversion and retention) is only of the order 7 and 10 between the 7-exo methyl isomer and the 7-endo methyl isomer.…”

Operational Criteria for Evaluation of Concertedness in Potential Pericyclic Reactions

“…Berson and Salem (1972) have suggested that overlap of the front lobe of the migrating carbon with the central lobe of the allylic system may strongly stabilize the transition state for the sr pathway. Berson and Salem (1972) have suggested that overlap of the front lobe of the migrating carbon with the central lobe of the allylic system may strongly stabilize the transition state for the sr pathway.…”

“…The idea that there might be a cause-and-effect relationship between "symmetry allowedness" and "concertedness" was further scrutinized by Baldwin (Baldwin and Fleming, 1970;Baldwin et ai, 1972) and Berson (1972). In part, confusion arises because of ambiguity in the term "relevant events," which appear in the foregoing definition of concerted reactions.…”

“…Baldwin and Fleming (1970) have presented detailed arguments that serve to distinguish energetically concerted reactions (Woodward and Katz, 1959;Doering et al, 1972) from those which are bondingly concerted in a molecular orbital sense (Salem, 1968;Silver, 1974) (i.e., reactions in which the bonding character of interacting molecular orbitals is preserved throughout the transformation). Berson (1972;Berson and Salem, 1972;Berson and Holder, 1973) and other investigators (Salem, 1970;Baldwin and Grayston, 1974) have presented examples of symmetry forbidden, concerted reactions. Berson (1972;Berson and Salem, 1972;Berson and Holder, 1973) and other investigators (Salem, 1970;Baldwin and Grayston, 1974) have presented examples of symmetry forbidden, concerted reactions.…”