DIMETHYLDIOXIRANE REACTIONS: RATE ACCELERATION DUE TO INTRAMOLECULAR H-BONDING

摘要

Absolute rate studies were carried out on a series of C—H insertion reactions of dimethyldioxirane (1a). The substrates were chosen so that the distance between a single tertiary C—H bond and an OH group could be varied. The measured rate constants indicate that a rate acceleration occurs when the distance between the reacting C—H bond and the OH group permits intramolecular H-bonding stabilization of the transition state. A similar study in related compounds without the OH group showed no effect of chain length on the rate of the C—H insertion reaction. A related study of the epoxidation reaction of 1a also found an increased rate when chain length permitted intramolecular H-bonding by an OH group.