Stereochemistry of enacyloxins. Part 3.1 (12′S,17′R,18′S,19′R)-Absolute configuration of enacyloxins, a series of antibiotics from Frateuria sp. W-315
Stereochemistry of enacyloxins. Part 3.1 (12′S,17′R,18′S,19′R)-Absolute configuration of enacyloxins, a series of antibiotics from Frateuria sp. W-315
Stereochemistry of enacyloxins. Part 3.1 (12′S,17′R,18′S,19′R)-Absolute configuration of enacyloxins, a series of antibiotics from Frateuria sp. W-315
The absolute configuration of the 12â²,17â²,18â²,19â²-positions of enacyloxins (ENXs), a series of polyhydroxy-polyenic antibiotics from Frateuria sp. W-315, was determined. As degradation of decarbamoyl (dec) ENX IIa gave (5R,6S,1â²E)-6-(but-1â²-enyl)-5-chloro-5,6-dihydro-2H-pyran-2-one, which corresponded to the 15â²â23â² skeleton of dec ENX IIa, its enantiomers were synthesized from tri-O-acetyl-D-glucal. Comparison of the HPLC retention time of these naturally derived and synthetic compounds revealed the 17â²R,18â²S,19â²R-configuration of ENXs. Hydrogenation and oxidation of ENX IIa gave methyl 13-hydroxy-6,12-dimethyltridecanoate, which was converted to the 13-MTPA ester. Comparison of the 1H NMR chemical shifts and the coupling constants with the model compounds revealed the 12â²S-configuration. This absolute stereochemistry is necessarily applicable to other enacyloxins.