Acceleration of transfer-hydrogenation of cyclohexene with palladium catalysts in the presence of polysaccharides

Transfer hydrogenation of alkenes is a very attractive reduction pathway, as it does not involve hazardous metal hydrides or high pressure hydrogen. It can be easily performed with isopropanol as a solvent and hydrogen donor, using a homogenous or heterogeneous palladium catalyst. We present here, for the first time, that the addition of a xerogel composed of natural polysaccharides to the transfer hydrogenation of cyclohexene with palladium salts or Pd/C in isopropanol tremendously increased the reaction activity rate. The Carrageenans forms, and especially iota, were found to be the most useful additives in two scales that were tested.