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A new metal-free catalytic approach for the synthesis of anti-Markovnikov methyl acetals from vinylarenes based on in situ generated HOI species is reported. The mechanistic investigations provided the solid evidence for the proposed mechanism.

A new metal-free protocol is described for the synthesis of terminal acetals by tandem oxidative rearrangement of olefins using oxone as an oxidant in the presence of iodine. Moreover, a one-pot procedure for the preparation of glycol mono esters from olefins is also presented for the first time using the same reagent system.

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Carbon–carbon (C–C) coupling is critically important in organic synthesis. Direct C–C coupling to replace two C–H bonds is preferred over coupling of two prefunctionalized C–intermediates but is synthetically challenging. While such coupling is feasible through homogeneous catalysis, the mechanism regarding how the two C–H bonds are activated and coupled by heterogeneous active metal atoms remains not well understood. This work demonstrates the need for a proximate metal–metal dimer site to facilitate heterogeneously catalyzed C–C coupling reactions. We demonstrate that dinuclear Pd2+ sites in (Pd2+)2-silicotungstate (Pd2ST) catalyzed oxidative C–C coupling of 2-methylfuran by O2 through synchronized double C–H activations under ambient conditions, selectively producing 5,5′-dimethyl-2,2′-bifuran (DMBF). Mononuclear Pd2+ ions in Pd1H2ST and H4ST are not active. The 13C NMR and DRIFT spectroscopies of adsorbed 13CO, combined with DFT and theoretical 13C NMR calculations, determined that dinuclear Pd2+ ions are separated by ∼3.5 Å on Pd2ST and 3.1 Å in the Pd2+C­(O)Pd2+ complex. XRD and TEM are used to confirm that the most active Pd2ST/SiO2 catalyst has near monolayer dispersion. 29Si MAS NMR is used to confirm the presence of the silicotungstate structure after calcination. The original silicotungstate Keggin structure is maintained after the Pd2ST/SiO2 is calcined.