Oxidation of Organoboranes with Trimethylamine N-Oxide Dihydrate

Recently it has been reported that the commercialy available, easily handled trimethylamine N-oxide dihydrate is an effective oxidizing agent for organoboranes. An examination of the efficiency and reactivity of this reagent under various reaction conditions was conducted. Alkenes were hydroborated to the corresponding alkylboranes, and the subsequent oxidations to alcohols were carried out using a slight excess of trimethylamine N-oxide dihydrate. The product yields at different tiem intervals were determined by glpc analysis.The oxidation can be carried out in hydrocarbon as well as ethereal solvents. The rate of oxidation is proportional to temperature. Furthermore, long reaction times at moderate temperatures are not detrimental to yields. The rates of reaction of alkyl groups in the organoborane were determined to be tertiary > cyclic secondary > acyclic secondary > $\text{n}$-primary > branched primary > vinyl.