Molecular mechanics calculations on cyclopentenyl compounds, products obtained by olefin metathesis of norbornadiene derivatives

Abstract

Molecular mechanics calculations (MM2) are used to elucidate energies and structures of possible reaction products in olefin metathesis of 2,3-dimethylnorbornadiene. The comparison of experimental and calculational results concerning norbornadiene itself shows excellent agreement both in energy and structure. The predicted isomers of lowest energy in a series of three different reaction products seem highly reliable and will lead to a more precise interpretation of the olefin metathesis reaction and the resulting product distribution. Some sixty different isomers have been considered and structures and energies are given. Nonplanarity of double bonds and van der Waals repulsions of closely related hydrogen atoms in polycyclic cycloolefins are considered in some detail. In order to reduce computing time and efforts in obtaining starting coordinates, a computer program for some dimeric structures was devised, which can combine minimized structures stemming from MM2 calculations.