Palladium-catalyzed transfer hydrogenolysis

Palladium-catalyzed transfer hydrogenolysis of benzyl acetate to give toluene has been achieved by using ammonium formate. Hydrogen-donating abilities of various formate salts were found to depend on the counter-ion K+>NH4+>Na+>NHEt3+>Li+>H+ [66]. 

Terminal allenes.1 A synthesis of 1,2-dienes (3) from an aldehyde or a ketone involves addition of ethynylmagnesium bromide followed by reaction of the adduct with methyl chloroformate. The product, a 3-methoxycarbonyloxy-l-alkyne (2), can be reduced to an allene by transfer hydrogenolysis with ammonium formate catalyzed by a zero-valent palladium complex of 1 and a trialkylphosphine. The choice of solvent is also important. Best results are obtained with THF at 20-30° or with DMF at 70°. 

The benzyl group can serve as an alcohol-protecting group when acidic conditions for ether cleavage cannot be tolerated. The benzyl C—O bond is cleaved by catalytic hydrogenolysis or with sodium in liquid ammonia. Benzyl ethers can also be cleaved with the use of formic acid, cyclohexene, or cyclohexadiene as hydrogen sources in transfer hydrogenolysis catalyzed by platinum or palladium. ... 

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