PMGB

To a stirred solution of the N-BOC derivative (0.01 mol) in 25 mL dichloromethane (in a round bottomed flask fitted with a gas bubbler since a gas is evolved) at room temperature was added 25 mL trifluoroacetic acid. The resulting mixture was stirred at room temperature for 5 h. The reaction mixture was evaporated below 50 ^oC and then poured to premixed solid sodium bicarbonate with few pieces of ice, extracted with dichloromethane, dried (Na₂SO₄) and evaporated to give the corresponding amine in quantitative yield.

Note:

1. We observed hydrolysis of sulfonamide group while trying to deprotect O-BOC using TFA.

2. We observed hydrolysis of ester group while trying to deprotect N-BOC using TFA.