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-M
TPA 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。