Enantioselective [2+2] Photocycloaddition Reactions of Enones and Olefins with Visible Light Mediated by
<i>N</i>
,
<i>N</i>
′‐Dioxide–Metal Complexes
作者:Han Yu、Shunxi Dong、Qian Yao、Long Chen、Dong Zhang、Xiaohua Liu、Xiaoming Feng
DOI:10.1002/chem.201804600
日期:2018.12.20
A 2‐alkenoylpyridine‐bound N,N′‐dioxide–TbIII complex has been found to absorb visible light to reach the excited state, leading to the direct visible‐light‐excited catalytic enantioselective [2+2] cycloaddition of 2‐alkenoylpyridines to various alkenes in the absence of an additional photosensitizer. Diverse enantioenriched cyclobutanes were successfully obtained (yields up to 70 %, >19:1 d.r., 92 %
已发现与2-链烯酰基吡啶结合的N,N'-二氧化物-Tb III络合物吸收可见光以达到激发态,从而导致2-链烯酰基吡啶直接可见光激发催化对映选择性[2 + 2]环加成在没有额外的光敏剂的情况下生成各种烯烃。成功获得了多种对映体富集的环丁烷(收率高达70%,> 19:1 dr,92%ee)。新型手性ter(III)络合物具有顺色和重原子效应,导致红移,较低的激发能和容易的系统间交叉,从而使天线2链烯酰基吡啶被激发。为了进行比较,手性N,N'-二氧化物–ScIII配合物与[Ru(bpy)3 ] Cl 2的结合在2'-羟基查耳酮与烯烃的对映选择性光环加成反应中非常有效,从而揭示了底物和金属盐均对该反应具有显着影响。