Enantioselective Halo-oxy- and Halo-azacyclizations Induced by Chiral Amidophosphate Catalysts and Halo-Lewis Acids

Catalytic enantioselective halocyclization
of 2-alkenylphenols
and enamides have been achieved through the use of chiral amidophosphate
catalysts and halo-Lewis acids. Density functional theory calculations
suggested that the Lewis basicity of the catalyst played an important
role in the reactivity and enantioselectivity. The resulting chiral
halogenated chromans can be transformed to α-Tocopherol, α-Tocotrienol,
Daedalin A and Englitazone in short steps. Furthermore, a halogenated
product with an unsaturated side chain may provide polycyclic adducts
under radical cyclization conditions.

本研究通过使用手性酰胺磷酸酯（chiral amidophosphate）催化剂与卤代路易斯酸（halo-Lewis acids），成功实现了2-烯基苯酚（2-alkenylphenols）与烯酰胺（enamides）的催化对映选择性卤代环化反应。密度泛函理论（Density functional theory）计算结果表明，催化剂的路易斯碱性（Lewis basicity）对反应活性与对映选择性具有重要作用。所得手性卤代色满（chiral halogenated chromans）可通过简短步骤转化为α-生育酚（α-Tocopherol）、α-生育三烯酚（α-Tocotrienol）、戴达林A（Daedalin A）以及恩格列酮（Englitazone）。此外，带有不饱和侧链的卤代产物可在自由基环化条件下生成多环加合物（polycyclic adducts）。