Enantioselective Intermolecular [2+2] Photocycloaddition Reaction of Cyclic Enones and Its Application in a Synthesis of (−)-Grandisol
作者:Saner Poplata、Thorsten Bach
DOI:10.1021/jacs.8b01011
日期:2018.3.7
The intermolecular [2+2] photocycloaddition of typical cyclic α,β-unsaturated enones, such as 2-cyclohexenone, with olefins was performed in moderate to good yields (42–82%) and with high enantioselectivity (82%–96% ee). An unusual substitution pattern at the chiral oxazaborolidine-AlBr3 Lewisacid complex that promotes the reaction was found to be crucial for the success of the reaction. The method
典型的环状 α,β-不饱和烯酮(如 2-环己烯酮)与烯烃的分子间 [2+2] 光环加成以中等至良好的产率(42-82%)和高对映选择性(82%-96% ee )。发现促进反应的手性恶唑硼烷-AlBr3 路易斯酸络合物的不寻常取代模式对反应的成功至关重要。该方法用于对映选择性合成单萜(-)-格兰地醇,以3-甲基-2-环己烯酮为原料,可分六步完成,总产率为13%。
Synthesis of optically pure enantiomers of grandisol