Oxidation of Allenes and Alkynes with Hydrogen Peroxide Catalyzed by Cetylpyridinium Peroxotungstophosphate (PCWP)

Article abstract of DOI:10.1021/jo00098a028

The oxidation of allenes and alkynes with hydrogen peroxide catalyzed by peroxotungstophosphate (PCWP) was examined.A variety of allenes were first converted into the corresponding α-ethoxy ketones upon treatment with 35percent H2O2 under the influence of PCWP in a mixed solvent consisting of ethanol and dichloromethane.When the reaction was carried out using tert-butyl alcohol as a solvent, approximately a 1:1 regioisomeric mixture of α-hydroxy ketones was obtained along with a small amount of α-tert-butoxy ketone.Oxidation of internal alkynes such as 4-octyne by the PCWP-H2O2 system under phase-transfer conditions using chloroform produced α,β-epoxy ketones in good yields.The same reaction in a mixed solvent of ethanol and chloroform gave α,β-unsaturated ketones rather than α,β-epoxy ketones.Plausible reaction paths are proposed for the oxidation of allenes and alkynes by the PCWP-H2O2 system.