Solvent effects on (3,3);sigmatropic rearrangements and mechanisms of allylic additions to benzaldehyde

he solvent effects on two different (3,3) sigmatropic rearrangements were examined in an effort to determine the results of medium changes on the rates of reaction and on the position of transition states. The aliphatic Cope rearrangement was examined in a variety of solvents and the rate of the reaction was correlated with cohesive energy density (c.e.d.). The correlation was found to be poor indicating that c.e.d. alone is an insufficient parameter to elucidate rate changes even for a nonpolar substrate. It has been previously established that the rate of the aliphatic Claisen rearrangement responds positively to an increase in solvent polarity and hydrogen bonding. The extent of bond breaking and bond making in allyl vinyl ether (AVE) in both an aqueous and a nonpolar medium were investigated using deuterated starting materials (AVE-4-;The mechanism of addition to benzaldehyde by diisopropyl tartrate (DIPT) derivatives of allyl boronate and allyl Grignard reagents were investigated with substituent and deuterium kinetic isotope effects. Competition experiments were used to determine the relative reactivties of substituted benzaldehydes and the derivatized product alcohols were analyzed by gas chromatograpy. The Hammett...