Tetrahedron Letters 44:733–735, 2003,Please follow this paper and try

Hi, 

You can try to use liquid ammonia as solvent. In these conditions, cysteine or methionine should not poison the catalyst. Adding BaSO4 or BF3.Et2O in the case of methionine could also help :) 

Thanks Margery.

Do you think it will help in case sulphur is present as thiourea moeity?

Hi,

You can try neat TFA at 60°C for overnight if you don't have BOC group there in. It worked for me sometime back

Acidic media can be used. 

You can use ammonium formate and pd/C system in methanol at 60°C in this way poisoning will also mask and with deCBZ or de benzylation

Dear Margery.

In one of your responses you mentioned that "thiourea moiety" is present in your reactant.

Please confirm this as my suggestion will depend on that.

Many conditions suggested above may lead to "peeling off" of the thiourea moiety.

Be careful before attempting on a "costly" material.

Best wishes

Yes the thiourea moeity is present.

Then you need to be careful, especially with reaction conditions requiring heating above room temperature.

Best wishes

You can use glacial AcOH at room temperature. The best is monitoring by TLC if the reaction has stopped because of poisoning, and adding if needed new wet aliquots of Pd/C into the vessel.