The Synthesis of a Series of N-t-Amyloxycarbonyl-oligo-l-proline

A series of N-protected l-proline oligomers, the di-, tri-, tetra-, penta-, hexa- and octamer, were synthesized by conventional methods. The proline imino-group was protected by the t-amyloxycarbonyl (Aoc) group, and the carboxyl group was protected as the benzyl ester during the synthesis. These Aoc-oligoprolines were valuable in elucidating the relationship between the conformation and the degree of polymerization of the polyprolines. The Aoc-protecting group was useful in purifying the intermediates and in obtaining crystals of the final compounds.