Transfer Hydrogenolysis of Benzylic Compounds

Transfer hydrogenolysis using Pd/C and cyclohexene has been used for de-N-benzylation in peptide synthesis. This process, however, is not suitable 

To the solution of the N,N-dibenzyltryptamine derivative in EtOH were added HC02NH4 (15 mol/mol tryptamine) and Pd black (2 mol Pd/mol tryptamine) and the mixture was refluxed under N2 for 12 hours. It was brought to room temperature and another batch of HC02NH4 and Pd black was added with stirring. This was followed by the addition of formic acid, and the reaction mixture was refluxed for another 12 hours.350 

During the asymmetric synthesis of erythro and threo a-substituted 3-amino esters, the dimethylbinaphthyl moiety (28 in Fig. 4.5) was removed using transfer hydrogenolysis. 

The detritylation of N-tryphenylmethylvaleric acid ester derivatives was accomplished by catalytic hydrogenolysis, both in the standard and catalytic transfer modes.338 The trityl precursor was suspended in a mixture of EtOH and AcOH, and HC02NH4 was added. Reduction began with the addition of 10% Pd/C (0.05 mol Pd/mol) and continued for 50 hours at 25°C. 

Both the benzylic C-O and the C-N bonds were cleaved during the synthesis of (4)-lactacystin. The hydrogenolysis of the oxazoline moiety on Pd/C, Pd(OH2)/C, or Pd black in MeOH proved unsuccessful, but catalytic transfer 

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