The structure of the antibiotic micrococcin P has been determined by 13C n.m.r. spectroscopy. IN earlier r e p ~r t s , l -~the structure of subunits A, B, C, D, and E (Figure ) of the antibiotic micrococcin Pl was established. We now demonstrate, on the basis of 13C n.m.r. spectroscopy, the presence of one molecule of subunits A, C, D, and E and two molecules of subunit B per molecule of the antibiotic and revise the constitution of subunit E. Furthermore, we show that these fragments account for the total composition of micrococcin P (1) and establish its complete structure.The noise-decoupled 13C n.m.r. spectrum of micrococcin P (l), recorded in (CD,),SO solution on a Rruker HX-360 spectrometer operating at 90.52 MHz, exhibits 48 signals.

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An X-ray crystallographic study on 4"-0-(4-iodobenzoyl)megalomicin A has led to the revision of the structures of the megalomicins and the XK-41 antibiotics. Crystals are orthorhombic, space groupP2,2,2, with a = 12.669(2), b = 19.501 (6), c = 25.741 (9) A, and Z = 4. The structure was solved by the heavy-atom technique, and 1 812 observed reflections led to a final R of 0.095. The novel amino-sugar previously thought to be D-rhodosamine has been shown to have the L-configuration and is therefore renamed L-megosamine. It has also been shown to be glycosidically attached to the tertiary 6-hydroxy group. The 13C n.m.r. and circular dichroism (c.d.) parameters of these macrolides are described. The syntheses of methyl aand P-D-rhodosaminide, methyl aand P-D-megosaminide, methyl a-and 6-L-megosaminide, methyl a-and (3-D-angolosaminide, and methyl 2,3,6-trideoxy-3-(dimethylamino) -a-D-xylo-hexopyranoside are described and their conformations and 13C n.m.r. parameters are discussed. Methyl a-D-and -L-amicetoside, methyl a-D-and -L-cineruloside and other model 4-oxopyranosides and pyrans have been synthesized. Their c.d. properties have been determined and they have been shown to exhibit Anti-Octant behaviour.

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