ELIMINATION OF THE BARRIER TO COPE REARRANGEMENT IN SEMIBULLVALENE BY LI+ COMPLEXATION

The coordination of a Li+ ion stabilizes the transition state for the Cope rearrangement of semibullvalene and essentially eliminates the barrier. At 0 K structure 1 is 0.7 kcal mol−1 lower in energy than the semibullvalene–Li+ complex. Ab initio calculations also indicate that both species are homoaromatic. (Figure Presented.) Copyright © 1993 by VCH Verlagsgesellschaft mbH, Germany