46 STRUCTURE OF IKARUGAMYCIN
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The structure of a new antibiotic, ikarugamycin (IM) (1) was proposed based on the following degradation reactions. Catalytic hydrogenation of IM afforded a hexahydro IM (2), which gave a deoxyoctahydro IM (3) on further hydrogenation. Both (2) and (3) were reduced to a deoxydecahydro IM (4) by lithium borohydride reduction. Ozonolysis of IM followed by acid hydrolysis afforded L-ornithine and (5). Starting from (3), α-DNP-ornithine and (9) were obtained as shown in the scheme. Oxidation of IM with permanganate yielded (15), (16), (17), (18), (14) and (5), and with chromic acid (15), (16), (17), (19), (20) and (21). Both (2) and (3) gave (16), (17), (22), (23), (24), (25) and (26) on chromic acid oxidation. However, (27) and (28) were obtained only from (3).
