CHEMISTRY DIOXIRANES .32. DIMETHYLDIOXIRANE REACTIONS - RATE ACCELERATION DUE TO INTRAMOLECULAR H-BONDING

Absolute rate studies were carried out on a series of C-H insertion re actions 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 accelerati on occurs when the distance between the reacting C-H bond and the OH g roup permits intramolecular H-bonding stabilization of the transition state. A similar study in related compounds without the OH group showe d no effect of chain length on the rate of the C-H insertion reaction. A related study of the epoxidation reaction of la also found an incre ased rate when chain length permitted intramolecular H-bonding by an O H group.