Transient-axial-chirality controlled asymmetric rhodium-carbene C(sp2)-H functionalization for the synthesis of chiral fluorenes
Transient-axial-chirality controlled asymmetric rhodium-carbene C(sp2)-H functionalization for the synthesis of chiral fluorenes
复制标题
瞬态轴向手性控制的不对称铑卡宾 C(sp(2))-H 官能化用于合成手性芴
DOI：
10.1038/s41467-020-16098-8
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发表时间：
2020-05-12
影响因子：
16.6
通讯作者：
Xu, Xinfang
中科院分区：
文献类型：
--
作者：
Dong, Kuiyong;Fan, Xing;Xu, Xinfang
在催化不对称反应中，手性分子的形成通常依赖于在立体决定步骤中从手性催化剂到产物的直接手性转移（点或轴向手性）。在此，我们公开了一种实现不对称反应的瞬时轴向手性转移策略。该方法依赖于将点手性从催化剂转移到具有轴向手性的二铑卡宾中间体，即瞬时轴向手性，因为该物质是反应的中间体。然后通过C（sp（2））-H官能化反应将瞬时手性转移到最终产物中，具有非常高的对映选择性。我们还推广了这种策略的不对称级联反应，涉及双卡宾/炔复分解（CAM），过渡金属催化的方法，以获得高收率高达99%ee.Detailed的DFT计算获得的手性9-芳基芴框架的瞬态轴向手性转移的模式和CAM反应的详细机制。手性分子的形成通常依赖于手性从催化剂到产物的直接传递。在这里，作者报道了一种基于从催化剂到具有轴向手性的二铑卡宾中间体的点手性转移的策略，然后通过C（sp（2））-H官能化将其转移到产物。
In catalytic asymmetric reactions, the formation of chiral molecules generally relies on a direct chirality transfer (point or axial chirality) from a chiral catalyst to products in the stereo-determining step. Herein, we disclose a transient-axial-chirality transfer strategy to achieve asymmetric reaction. This method relies on transferring point chirality from the catalyst to a dirhodium carbene intermediate with axial chirality, namely a transient-axial-chirality since this species is an intermediate of the reaction. The transient chirality is then transferred to the final product by C(sp(2))-H functionalization reaction with exceptionally high enantioselectivity. We also generalize this strategy for the asymmetric cascade reaction involving dual carbene/alkyne metathesis (CAM), a transition-metal-catalyzed method to access chiral 9-aryl fluorene frameworks in high yields with up to 99% ee. Detailed DFT calculations shed light on the mode of the transient-axial-chirality transfer and the detailed mechanism of the CAM reaction. The formation of chiral molecules generally relies on direct chirality transfer from catalyst to products. Here, the authors report a strategy based on point chirality transfer from the catalyst to a dirhodium carbene intermediate with axial chirality, which is then transferred to products via C(sp(2))-H functionalization.