创新霉素的立体化学研究

THE STEREOCHEMISTRY OF CHUANGXINMYCIN

由化学方法证明创新霉素的绝对构型为3S,4R,如式1所示.与已知具有相同骨架的抗生素indolmycin(7)的绝对构型相反,为生源方面饶有兴趣的问题.去甲创新霉素(14)的羧基及去羧创新霉素(18)的甲基均以横键为最佳构象,因此似无顶端(anomeric)效应.由此可以推断创新霉素在溶液中较大的羧基是横键,甲基是竖键.这一点与固态X衍射结果一致.

Chuangxinmycin was shown by chemical correlation to have 3S,4R configuration as shown by 1.It is surprising that 1 has opposite absolute configuration as indolmycin(7)with the same carbon skeleton.The carboxyl group of norchuangxinmycin(14)and the methyl group of decarboxychuangxinmycin(18)were found to have preferred equatorial conformations with no observable anomeric effect in the former.Thus the bulkier carboxyl group of 1 itself must adopt the equatorial position predominantly,if not exclusively,in solution,a situation already found prevailing in the crystalline state by X-ray diffraction.