Synthesis of Streptolidine (Roseonine, Geamine)

Streptolidine (roseonine, geamine) (1), a guanidino amino acid component of the streptothricin group antibiotics, was synthesized starting from d-ribose (8). The epimino compound (11b) was prepared from 8 in five synthetic steps. Azidolysis of 11b gave the arabino-type compound (12b), which in turn was converted to the key intermediate tribenzyloxycarbamido lactone (23b) by oxidation of C-1. The lactone 23b was rearranged to the free lactam (4) after deprotection, and then guanidinated with cyanogen bromide. The identity of the hydrolysis product of this guanidino lactam with natural streptolidine in all respects certified the proposed structure involving the steric configurations.