Mechanistic insights into the malonoyl peroxide syn-dihydroxylation of alkenesElectronic supplementary information (ESI) available: Experimental procedures, characterisation data, copies of NMR spectra for all compounds, detailed procedures for kinetics, DFT modelling and CIF files. CCDC 936074-936077. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3sc53256a

• Main Authors: Rawling, Michael J, Rowley, Julian H, Campbell, Matthew, Kennedy, Alan R, Parkinson, John A, Tomkinson, Nicholas C. O
• Format: Article
• Language: English
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c3sc53256a

A detailed mechanistic understanding of the malonoyl peroxide mediated dihydroxylation of alkenes is presented. The reaction is first order in both alkene and peroxide with stoichiometric water playing a dual role. An ionic mechanism is proposed and supported by the use of 18 O isotopically labelled peroxide, a radical clock probe and DFT calculations. Hammett analysis suggests the reaction proceeds via a discrete carbocation intermediate which is consistent with the stereochemical outcome of the transformation. A subsequent Woodward-type 1,3-dioxolan-2-yl cation has been trapped in situ and the mechanism of hydrolysis defined by isotopic labelling studies. Stable reaction intermediates have been isolated and characterised by X-ray crystallographic analysis and minor competing reaction pathways identified. A detailed mechanistic understanding of the malonoyl peroxide mediated dihydroxylation of alkenes is presented.