Rear side acceleration

As a whole, our set of measurements therefore shows that, contrary to what is usually observed under low contrast conditions [21, 71], BWD protons originating from the laser-irradiated surface have practically the same characteristics as the FWD protons from the target rear side, suggesting a quasi-symmetrical TNSA acceleration in the two directions. 

The cationic cyclopropyl to allyl rearrangement is always disrotatory. If a cyclopropyl cation 9 or 14 is involved, both disrotatory modes are electronically equivalent, and their ratio is determined by steric interactions in the transition state. If, however, cyclopropane 16 rearranges to an allyl cation 17 in a synchronous reaction, bypassing the cyclopropyl cation 4, only the disrotatory mode, that moves the electron density of the breaking bond to the rear side of the leaving group X, occurs. This anchimeric assistance causes a kinetic acceleration of the rearrangement by a factor of at least 10 to 10 . °... 

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