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
作者:Ryo Takeuchi、Hiromasa Kiyota、Manabu Yaosaka、Toshihiko Watanabe、Keijiro Enari、Takeyoshi Sugiyama、Takayuki Oritani
DOI:10.1039/b104341m
日期:2001.10.11
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.
研究人员测定了烯酰环毒素(ENXs)的12â²,17â²,18â²,19â²-位的绝对构型,烯酰环毒素是来自弗氏菌W-315的一系列多羟基多烯抗生素。癸氨基甲酰基(癸)ENX IIa降解后得到(5R,6S,1â²E)-6-(丁-1â²-烯基)-5-氯-5,6-二氢-2H-吡喃-2-酮,与癸ENX IIa的15â²â23â²骨架相对应。通过比较这些天然衍生化合物和合成化合物的高效液相色谱保留时间,发现了ENXs的17â²R、18â²S、19â²R构型。ENX IIa 经氢化和氧化后得到 13-羟基-6,12-二甲基十三烷酸甲酯,并转化为 13-MTPA 酯。将 1H NMR 化学位移和耦合常数与模型化合物进行比较,发现了 12â²S-构型。这种绝对立体化学结构必然适用于其他烯丙菊酯。