Rearrangement of linalool, geraniol, nerol and their derivatives

Abstract

Acid-catalyzed conversion of linalool into geraniol, nerol, and a-terpineol is slower than the corresponding reactions of geraniol and nerol, because the tertiary linalyl carbocation reverts to linalool rather than going forward to rearranged products. The linalyl carbocation does not lose its stereochemical identity, and oxygen exchange of linalool is faster than rearrangement or cyclization. Solvolyses of linalyl esters and chloride are faster than those of the geranyl and neryl derivatives. These solvolyses are different from acid heterolysis of linalool in that there is extensive racemization of linalool, but cyclization to a-terpineol goes with considerable retention of configuration. Participation by the 6,7-double bond controls the stereochemistry of linalool heterolysis and solvolysis of linalyl esters, but it does not markedly affect the reaction rates