Stepwise Cross-Couplings of a Dibromo-γ-methylenebutenolide as an Access to <i>Z</i>-Configured α-Alkenyl-γ-alkylidenebutenolides. Straightforward Synthesis of the Antibiotic Lissoclinolide
作者:Reinhard Brückner、Achim Sorg、Frederik Blank
DOI:10.1055/s-2005-868506
日期:——
The Z-isomer of α-bromo-γ-(bromomethylene)butenolide was prepared from α-angelica lactone or levulinic acid in three and four steps, respectively. Successive Stille-couplings with an unsaturated stannane, with the potential to use a different second unsaturated stannane, involved the γ-substituent first and the α-substituent thereafter. Thereby, α-alkenyl-γ-alkylidenebutenolides and their arene analogs were obtained Z-selectively.
Z-异构体的α-溴-γ-(溴亚甲基)丁烯酮是分别从α-天使醇内酯或乙酰丙酸通过三步和四步合成的。通过与不饱和的锡烷进行连续的Stille偶联反应,首先引入γ取代基,然后引入α取代基,这允许使用不同的第二种不饱和锡烷。因此,获得了α-烯基-γ-烷基亚丁烯内酯及其芳烃类似物,具有Z选择性。