Divergent and Synergistic Photocatalysis: Hydro- and Oxoalkylation of Vinyl Arenes for the Stereoselective Synthesis of Cyclopentanols via a Formal [4+1]-Annulation of 1,3-Dicarbonyls

The controllable
divergent reactivity of 1,3-dicarbonyls is described,
which enables the efficient hydro- and oxoalkylation of vinyl arenes.
Both reaction pathways are initiated through the formation of polarity-reversed C-centered-radical intermediates at the active methylene
center of 1,3-dicarbonyls via direct photocatalytic C–H bond
transformations. The oxoalkylation of alkenes is achieved under aerobic
conditions via a Cu­(II)-photomediated rebound mechanism, while
the corresponding hydroalkylation becomes possible under a nitrogen
atmosphere by the combination of 4CzIPN and a Brønsted base.
The breadth of these divergent protocols is demonstrated in the late-stage
modification of drugs and natural products and by the transformation
of the products to a variety of heterocycles such as pyridines, pyrroles,
or furans. Moreover, the two catalytic modes can be combined synergistically
for the stereoselective construction of cyclopentanol derivatives
in a formal [4+1]-annulation process.

本文详细阐述了1,3-二羰基化合物的可控发散反应性，该反应性使得乙烯基芳烃的高效水合和氧合烷基化成为可能。两种反应路径均通过在1,3-二羰基的活性亚甲基中心通过直接的可见光催化C-H键转化形成极性反转的C中心自由基中间体而启动。在好氧条件下，通过Cu(II)-光介导的反弹机制实现烯烃的氧合烷基化，而在氮气气氛下，通过4CzIPN与布朗斯台德碱的结合，使得相应的氢烷基化成为可能。这些发散性方法的应用范围在药物和天然产物的后期修饰以及将产物转化为各种杂环（如吡啶、吡咯或呋喃）中得到体现。此外，这两种催化模式可以协同作用，在形式上的[4+1]环化过程中，选择性地构建环戊醇衍生物。