Triethoxysilane-Palladium acetate

The hydrogenation of alkenes and alkynes in water can also use silanes as hydrogen sources. Tour reported that by using palladium acetate as catalyst, triethoxysilane reduced C-C unsaturated bonds to saturation in a mixture of THF and water.18 The reaction showed excellent chemo- and stereoselectivity. Water was essential to the reaction. In the absence of water, 95% of the starting alkene remained unchanged (Eq. 3.3). 

The exocyclic C — C double bond in the chlorin can be reduced by catalytic hydrogenation in tetrahydrofuran/water in the presence of palladium(II) acetate with triethoxysilane as hydrogen source to yield under kinetic control cw-stereoisomers, which can be transformed by treatment with /)-toluenesulfonic acid in methanol to the thermodynamically favored trans-isomers.27d... 

A simple alternative to the Lindlar reduction process has been recognized.95 The palladium(II) acetate-catalyzed polymerization of triethoxysilane in water produces finely divided palladium metal dispersed on a polysiloxane matrix with concomitant hydrogen evolution. Addition of (EtO)3SiH to the mixture of an alkyne and all other necessary constituents allows facile and selective reduction of the alkyne without an external hydrogen source ... 

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