A suspension of 107.3 g Z-Gln(Mtt)OH (200 mM) in 800 ml methanol and 200 ml IN hydrochloric acid is hydrogenated at room temperature and normal pressure in the presence of 0.4 g palladium on carbon (10%) catalyst. On completion of the hydrogen uptake the catalyst is filtered off, washed with methanol and the filtrate, after addition of 27.9 ml triethylamine (200 mM) and 200 ml water, concentrated to a volume of about 600 ml. The formed crystalline precipitate is filtered off and washed with water until the washings are chloride-free. The obtained H-Gln(Mtt)OH contains 0.5-1 mole water and decomposes slowly above 231° C. Yield 85%.
