In their analysis of experiments and in their planning of syntheses, organic chemistsconsciouslyorunconsciouslytendtousetheprincipleofleastmotion, thechemicalequivalentofOccam'srazor. Inrearrangementreactionsthispr- ciple is violated and may make rearrangements problematic reactions. At the sametime,thereisalwaysfascinationintheunexpectedandsorearrangement reactionsarealsoanattractive?eldofstudy. Consequently, ourunderstanding of rearrangement reactions is now quite advanced and allows strategic uses in organic synthesis. Here, a helpful tool that may easily be overlooked is thein?uence...