Uses
It finds its application as a reagent for protection of carboxyl termini of peptides as 4-picolyl esters, providing a polar 'handle' which aids in separation and purification of the peptide. The group can be introduced in the presence of a base, e.g. tetramethylguanidine, is stable to acid-catalyzed removal of Cbz protecting group and can be removed by base, Na in liquid ammonia or catalytic hydrogenolysis. It is also applied in conjunction with Amberlyst?15 resin in peptide synthesis. It is an important raw material and intermediate used in organic synthesis, pharmaceuticals and agrochemicals.
Purification Methods
Purify it by recrystallisation from EtOH or EtOH/dry Et2O. It melts between 171o and 175o, and the clear melt resolidifies on further heating at 190o and turns red to black at 280o but does not melt again. The picrate-hydrochloride (prepared in EtOH) has m 146-147o. The free base is an oil. [Mosher & Tessieri J Am Chem Soc 73 4925 1951, Beilstein 20 III/IV 2752.]
