Affiliation:
1. Lehrstuhl für Organische Chemie II Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
2. Department of Chemistry Yale University 225 Prospect St. New Haven CT 06520 USA
Abstract
AbstractHeavy‐atom tunneling limits the lifetime and observability of bicyclo[4.1.0]hepta‐2,4,6‐triene, a key intermediate in the rearrangement of phenylcarbene. Bicyclo[4.1.0]hepta‐2,4,6‐triene had been proposed as the primary intermediate of the rearrangement of phenylcarbene, but despite many efforts evaded its characterization even in cryogenic matrices. By introducing fluorine substituents into theortho‐positions of the phenyl ring of phenylcarbene, the highly strained cyclopropene 1,5‐difluorobicyclo[4.1.0]hepta‐2,4,6‐triene becomes stable enough to be characterized in argon matrices. However, even at 3 K this cyclopropene is only metastable and rearranges via heavy‐atom tunneling to the corresponding cycloheptatetraene. Calculations suggest that fluorination is necessary to slow down the tunneling rearrangement of the bicycloheptatriene. The parent bicycloheptatriene rapidly rearranges via heavy‐atom tunneling and therefore cannot be detected under matrix isolation conditions.
Funder
Deutsche Forschungsgemeinschaft