This computational study investigates the conformationally restricted allenyl cope rearrangement of <i>syn</i>-7-allenylnorbornene using recently developed density functional theory (DFT) functionals and compares the results to past DFT and complete active space self-consistent field (CASSCF) calculations performed on the same reaction. The results from these calculations were compared to the experimental research done on the same reaction, which produced multiple stereoisomers, suggesting the reaction proceeded through a non-concerted mechanism. The CASSCF level calculations reported that the mechanism for this rearrangement followed two non-concerted pathways with a common biradical intermediate. These pathways accurately reproduced the stereoselectivity of products found in the experimental results of this reaction. Therefore it was concluded that CASSCF calculations predicted the correct mechanism for this rearrangement. Past investigation of this mechanism with DFT functionals B3LYP, BLYP, and BPW91 were unable to model the experimental stereoselectivity but were able to reproduce portions of the mechanism found by CASSCF calculations, including the biradical intermediate essential for the formation of the products. In this study, the Minnesota series of DFT functionals were used in an attempt to improve upon the B3LYP functional. However, the newer functionals found a concerted mechanism in all cases and were unable to reproduce the needed stereoselectivity. Therefore it was concluded that the newer Minnesota series of DFT functionals do not improve upon past DFT calculations and instead find less accurate mechanistic pathways than B3LYP.

Further computational investigation on the conformationally-restricted allenyl cope rearrangement of <i>Syn</i>-7-allenylnorbornene

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Further computational investigation on the conformationally-restricted allenyl cope rearrangement of Syn-7-allenylnorbornene