Tandem alcohol oxidation, alkene hydrogenation

Scheme 9 Proposed mechanism and substrate scope for tandem alcohol oxidation/Wittig reaction/alkene hydrogenation sequence...

This C - H activation event is reversible, and is required to achieve catalytic turnover [62], A series of alcohols, mostly secondary benzylic examples, have been oxidized using this catalyst. The catalytic activity does not match that of the Ir examples described above, but it has been used in several tandem reactions that feature both dehydrogenation and hydrogenation steps to achieve interesting transformations. One example is a tandem alcohol oxidation/Wittig reaction/alkene hydrogenation sequence (Scheme 9) [61,62],... 

Using another Ru carbene catalyst, Williams and co-workers were able to develop a tandem process involving alcohol oxidation followed by a Wittig reaction and hydrogenation of the resulting alkene. Interestingly, C-H bond activation of the carbene ligand was observed in this reaction (Scheme 12.9). 

Two tandem alkene metathesis-oxidation procedures using Grubb s second-generation ruthenium catalyst resulted in unique functional group transformations. Use of sodium periodate and cerium(III) chloride, in acetonitrile-water, furnished cis-diols. Oxidation with Oxone, in the presence of sodium hydrogencarbonate, yielded a-hydroxy ketones.296 Secondary alcohols are oxidized to ketones by a hydrogen... 

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