DESIGN OF SUBSTITUTED SEMIBULLVALENES SUITABLE FOR CONTROL OF THE COPE REARRANGEMENT BY 2 PS IR LASER-PULSES

A systematic experimental search for substituted semibullvalenes yield s systems which have nearly thermoneutral reactants and products (Delt a H-0 approximate to 0.5-1 kJ mol(-1)) separated by moderately low bar riers GRAPHICS e.g. 2,6-dicyanoethylmethylsemibullvalene DEM-SBV (= 7c reversible arrow 7c'). Theoretical model simulations suggest that t heir Cope rearrangement may be controlled by two infrared picosecond ( IR ps) laser pulses: The first pump pulse excites the reactants to the transition state, represented by a delocalized wave packet with energ y above the potential barrier. The second dump pulse stabilizes the pr oducts.