a ring inversion occurs in their piperidine ring system and determined the relative stereochemistry by capturing each half-chair conformer as cyclic carbamates 26 and 27, respectively. Utilizing this protocol total syntheses of (±)-1 and its diastereomer (±)-2 have been accomplished and the relative stereochemistry of virantmycin has been established as shown in 1.
通过分子内的氮烯加成反应作为关键步骤,已经开发出了有效的,立体定向的途径来制备维他霉素的
四氢喹啉环模型3和4。在4和3的NOE实验中,我们发现在其
哌啶环系统中发生了环反转,并通过分别捕获每个半椅子构象异构体为环状
氨基甲酸酯26和27来确定相对立体
化学。利用该方案,已经完成了(±)-1及其非对映异构体(±)-2的全部合成,并且建立了维兰霉素的相对立体
化学,如图1所示。