Quest for 2,3-Secopyramidane: Computations Hint at Elusive Structure during Skattebo̷l Rearrangement of
Murray G Rosenberg1, Udo H Brinker2
1Independent Researcher, 216 Harry L Dr., Johnson City, New York 13790, United States.
None:
The ωB97X-D/def2-TZVP + 0.955(EZPV) theoretical model was used to determine if 2,3-secopyramidane (tricyclo[2.1.0.01,3]pentane) participates during the Skattebo̷l rearrangement of endo-2-ethenylcycloprop-1-ylidene. Intrinsic reaction coordinate animations show an almost barrierless attempt at 1,2-addition of the divalent C atom to the ethenyl double bond because the transition state is stabilized by intramolecular σ- and π-complexation. The formation of 2,3-secopyramidane is incomplete, however, and retro-1,2-addition takes over, leading to ring-puckered cyclopent-3-en-1-ylidene, a bishomoaromatic carbene. Ring-flattening is followed by a 1,2-H atom shift yielding cyclopenta-1,3-diene.
More Related Videos
Related Concept Videos
Thermal and Photochemical Electrocyclic Reactions: Overview
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Thermal Sigmatropic Reactions: Overview
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in...


