A novel process for the regio- and stereospecific synthesis of polyprenylated quinone derivatives, such as Vitamin K1, K2 and Ubiquinone, has been achieved exploiting dithioacetal-, especially 1,3-dithiane-, mediated Umpolung chemistry which works along a new concept "Inhibiting resonance delocalization (IRD)" to overcome isomerization generated due to delocalization of allylic carbanions on the π-electron cloud of an allylic system. The present novel synthesis of all-trans Vitamins K1, K2 and Ubiquinone is achieved by coupling of a quinone group with a polyprenyl side chain where either of the two moieties may have 1,3-dithiane as a terminal group while undergoing umpolung chemistry. Similarly while coupling two polyprenyl fragments to each other in building of the all-trans side chain. A stereospecific synthesis of vitamin K1 was also achieved along the same synthetic outline using a chiral hexahydrofarnesyl derivative retaining optical and geometrical isomeric properties equivalent to those of the natural K1.
利用二
硫代
乙缩醛,特别是 1,3-二
硫代
乙缩醛介导的 Umpolung
化学,实现了一种新工艺,可进行多烯基醌衍
生物(如
维生素 K1、K2 和
泛醌)的区域和立体特异性合成,该工艺采用了一种新概念 "抑制共振失焦(IRD)",以克服由于烯丙基体系 π 电子云上的烯丙基碳离子失焦而产生的异构化。本新型全反式
维生素 K1、K2 和
泛醌的合成是通过醌基与聚
丙烯酰基侧链的偶联实现的,在偶联过程中,两个分子中的任何一个都可能以
1,3-二噻烷作为末端基团。同样,在建立全反式侧链的过程中,两个多烯基片段也会相互偶联。按照同样的合成方法,我们还利用一种手性六氢法
萘基衍
生物实现了
维生素 K1 的立体特异性合成,该衍
生物保留了与天然 K1 相同的光学和几何异构特性。