De-protection

The deprotection of functional groups is often used in the Life Science and Fine Chemicals Industry. Most deprotection reactions applied on an industrial scale involve the cleavage (hydrogenolysis) of N- and O-benzyl protective groups. A protective group for N that can be easily removed by hydrogenation at lower temperature is the carbobenzyloxy group, also called Cbz or Z group.

Typical reaction conditions are low pressure (1-5 bars) and low temperature (20-100 °C). The cleavage of N-benzyl protective groups require higher temperature than the cleavage of O-benzyl protective groups. The catalyst of choice is often unreduced palladium on activated carbon as this works fine for most of the de-protection reactions, and gives typically excellent results. Sometimes reduced catalysts are required. The reaction rate depends strongly on the leaving group and can be arranged in the following order: O-C(O)-N-R > O-C(O)-R > O-Ph > O-CH₂-R. Addition of acid typically increases the reaction rate.

Dedicated Catalysts for De-protection 

E 196 NN/W 5% Pd
E 105 N/W 5% Pd
E 105 O/W 5% Pd
E 107 MA/W 5% Pd
E 105 NN/W 5% Pd
E 101 NE/W 10% Pd
E 101 NE/W 20% Pd
E 105 R/W 5% Pd (Z group deprotection)
B 113 W