Efficient ortho-formylation in vitamin E series, application to the semi-synthesis of natural 5- and 7-formyl-δ-tocotrienols revealing an unprecedented 5-bromo-7-formyl exchange
作者:Khaled Alsabil、Guillaume Viault、Sorphon Suor-Cherer、Jean-Jacques Helesbeux、Joumaa Merza、Vincent Dumontet、Luis Manuel Peña-Rodriguez、Pascal Richomme、Denis Séraphin
DOI:10.1016/j.tet.2017.10.039
日期:2017.12
Semi-synthesis of 5- and 7-formyltocopherols and tocotrienols has been developed by ortho-formylation of C-5 or C-7-unsubstituted vitamin E derivatives (14 examples) up to 90% yield, through heating in the presence of respectively 10-10-15 equivalents of MgCl2-Et3N-(CH2O)n. Formylation of 5-bromo-δ-tocotrienol revealed an unprecedented 5-bromo/7-formyl exchange and yielded 7-bromo-5-formyl-δ-tocotrienol
通过分别在10到10的条件下加热将C-5或C-7-未取代的维生素E衍生物(14个实例)进行邻甲酰化,开发了5-和7-甲酰基生育酚和生育三烯酚的半合成方法。-10-15当量的MgCl 2 -Et 3 N-(CH 2 O)n。5-溴-δ-生育三烯酚的甲酰化显示出前所未有的5-溴/ 7-甲酰基交换,并产生了7-溴-5-甲酰基-δ-生育三烯酚作为主要产物。次要的5-溴-7-甲酰基-δ-生育三烯酚通过三个步骤导致先前从藤黄的茎皮中分离出的7-甲酰基-δ-生育三烯酚。