Regio- and stereoselectivity in the decatungstate photocatalyzed alkylation of alkenes by alkylcyclohexanes

Tetrabutylammonium decatungstate (WO) photocatalyzes radical alkylation reactions starting directly from alkanes. When using rert-butylcyclohexane and methylcyclohexane as the radical precursors, the addition to electrophilic alkenes (β,β-dialkylmethylenemalononitriles, acrylonitrile, methyl acrylate, methyl vinyl ketone) is regioselective and exclusively gives 3and 4-substituted cyclohexyl adducts, with no significant functionalization of the other positions. Furthermore, when a β,β-disubstituted alkene is used, the reaction is stereoselective (cis stereochemistry for the 1,3-cyclohexane derivatives and trans for the 1,4 isomers). Some of the reactions have also been carried out by using benzophenone as the photocatalyst, giving the same product distribution. However, the decatungstate anion is a superior catalyst from a preparative point of view, because it is efficient at low concentrations (0.002M, 2mol%) and allows for a simple work up. From a mechanistic point of view, the role o...