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Ab initio direct dynamics study of cyclopropyl radical ring-opening
1Department of Chemistry and Institute for Scientific Computing, Wayne State University, Detroit, MI 48202, USA.
Journal of the American Chemical Society
|March 28, 2002
Summary
Stereochemistry of cyclopropyl radical ring-opening was simulated. While disrotatory is predicted, conrotatory pathways were observed, indicating incomplete energy redistribution in the allyl radical product.
Area of Science:
- Chemical Dynamics
- Quantum Chemistry
- Reaction Mechanisms
Background:
- The electrocyclic ring-opening of cyclopropyl radical is a fundamental reaction in organic chemistry.
- Understanding its stereochemical outcome is crucial for predicting product formation.
Purpose of the Study:
- To investigate the stereochemistry of the cyclopropyl radical's electrocyclic ring-opening reaction.
- To explore the dynamics and product distribution using computational methods.
Main Methods:
- Quasiclassical direct dynamics simulations were performed.
- CASSCF(3,3)/6-31G(d) level of theory was employed.
- Trajectories were initiated from the transition state (TS) using Boltzmann distribution.
Main Results:
- Intrinsic reaction coordinate calculations predicted disrotatory stereochemistry.
- However, 43% of simulated trajectories followed the conrotatory path.
- Four distinct trajectory types were observed in the 200 fs dynamics of the allyl radical product.
Conclusions:
- Initial reaction stereochemistry is predominantly disrotatory, but conrotatory pathways are significant.
- Intramolecular vibrational energy redistribution and internal rotation are incomplete within 200 fs.
- A statistical distribution of allyl isomers was not achieved on this timescale.
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