An AMI study of the cope rearrangements of bullvalene, barbaralane, semibullvalene, and derivatives of semibullvalene

Abstract

AMI calculations are reported for the Cope rearrangements of [3,3,2,02,8] tricyclodeca-3,7,9-triene (bullvalene; 6), (3,3,1,02,8] tricyclonona-3,7-diene (barbaralane; 7), [3,3,0,02,8] tricyclonona-3,7-diene (semibullvalene; 8), and 12 derivatives of 8. All the reactions were predicted to take place via typical aromatic pericyclic transition states, unlike chair Cope rearrangements but like the boat rearrangement of 1,5-hexadiene. A second biradicaloid transition state of higher energy was found for 6 and 8. CN or F in 8 at C2, C4, C6, or C8 is predicted to accelerate the reaction.