Chemical degradation and X-ray crystal structure of rosaramicin

Kijanimicin. Part 3. Structure and absolute stereochemistry of kijanimicin

“…data for (48)- (52) are given in Table 1 and it is evident from the data for (48), that no rearrangements had occurred within the aglycone during the course of the methanolysis. The deshielding (-t-10.3) observed at C-32 in (48) relative to kijanimicin (1) clearly showed that the hydroxy group that was free in the (-4.2) and C-19 (-2.4) were all shielded in (1) due to the attachment of the D-kijanose unit at C- 17. The A& values in going from (48) to (14) showed similar values for C(16)--C (19) to those just discussed, indicating that the kijanose unit was glycosidically linked at C-17. The A& values observed in going from (48) to the 26-0-methyl ether (49) were consistent with what had previously been found with ( 2) and (15).…”

“…Overlapping fractions were further purified by preparative t. 1.c. on silica gel plates using 50% ethyl acetate in dichloromethane as the eluant to give an additional 108 mg of (19) (281 mg, 55%) as a colourless amorphous solid (Found: C, 56.75; H, 6.0;I, 11.95;N, 2.45. C50H631N2013 requires C, A, , , , , .…”

“…The di-iodobenzoate (20) crystallized from tetrahydrofuran-hexane as fine needles, which were also unsatisfactory for X-ray studies. The methyl ethers (19) and ( 21) could be obtained only as amorphous solids. Further degradations were therefore required to elucidate the structure of kijanimicin (I).…”

2-Diazo-1-(1,1-dioxothiomorpholin-4-yl)ethanone

“…For related structures found in the Cambridge Structural Database (Version 5.32 of November 2010; Allen, 2002), see: Fenlon et al (2007); Haynes et al (2006); Wang et al (2006);Miller et al (1991); Foces-Foces et al (1988); Ganguly et al (1980); Herdklotz & Sass (1969). For details of the synthesis, see: Kaupang (2010); Toma et al (2007) and for the synthesis of related diazoacetamides, see: Kaupang et al (2010); Kaupang (2010); Ouihia et al (1993).…”

Novel semisynthetic oxo and alkyl macrolide antibacterials and related derivatives

“…De-epoxidation of 20-C-butylrosaramicin (10) with chromous ions at acidic pH2' afforded (20), which was in turn converted into the hydrazone derivative (21).…”