Stereoselective synthesis of spiroethers and spiroketals via photoaddition of dihydro-4-pyrones to 1,3-dioxin-4-ones
作者:Nizar Haddad、Zehavit Abramovich、Igor Ruhman
DOI:10.1016/0040-4039(96)00602-8
日期:1996.5
intramolecular photoaddition of dihydro-4-pyrones to 1,3-dioxin-4-ones, followed by subsequent fragmentation affording a spiroether which provides, after Baeyer-Villager oxidation, the corresponding spiroketal with complete retention of configuration at the spirocenter. The configuration of this center is defined by the facial selectivity of the chiral dioxinone at the photoaddition step. Thus, this
提出了一种多功能和立体选择性合成螺醚和螺环酮的方法。关键步骤基于分子内将二氢-4-吡喃酮光加成为1,3-二恶英-4-酮,随后进行片段化,得到螺醚,在Baeyer-Villager氧化后,该螺醚可提供相应的螺环酮,并保留其构型。螺旋中心。该中心的构型由在光加成步骤中手性二恶英酮的面部选择性定义。因此,该方法能够实现热力学上较不稳定的螺环酮的立体选择性合成,螺环酮通常通过依赖平衡的大多数常规方法以异构体混合物形式生产。在存在内标物的情况下,合成热力学较不稳定的螺酮,然后进行受控差向异构化,