中国科学院上海有机化学研究所丁奎岭团队报道了钌催化融合杂芳烃的碳环选择性加氢反应。相关研究成果于2024年12月11日发表在《美国化学会杂志》。

苯并稠合杂芳烃的均相催化氢化通常提供部分氢化产物，其中杂芳环优先被还原，如喹啉氢化，生成1,2,3,4-四氢喹啉。

该文中，研究人员报道了一种使用手性螺缩酮基二膦（SKP）的Ru配合物，作为催化剂的稠合N-杂芳烃（喹啉、异喹啉、喹喔啉等）的碳环选择性氢化方法，以高化学选择性提供相应的5,6,7,8-四氢产物。

这种催化体系对于带有硼基或氨基的，稠合杂芳烃的不对称碳环氢化也是有效的。实验研究为催化的均相性提供了强有力的支持，并提出了氢化的内球机制。DFT计算表明，氢化是由喹啉碳环的η4配位活化为SKP的Ru二氢化物络合物，然后由金属到配体的氢化物转移引发。随后的碳循环还原通过H₂氧化加成和C-H还原消除的连续步骤进行。

附：英文原文

Title: Ruthenium-Catalyzed Carbocycle-Selective Hydrogenation of Fused Heteroarenes

Author: Chenguang Luo, Chaozheng Wu, Xiaoming Wang, Zhaobin Han, Zheng Wang, Kuiling Ding

Issue&Volume: December 11, 2024

Abstract: The homogeneous catalytic hydrogenation of benzo-fused heteroarenes generally provides partially hydrogenated products wherein the heteroaryl ring is preferentially reduced, such as quinoline hydrogenation, leading to 1,2,3,4-tetrahydroquinoline. Herein, we report a carbocycle-selective hydrogenation of fused N-heteroarenes (quinoline, isoquinoline, quinoxaline, etc.) using the Ru complex of a chiral spiroketal-based diphosphine (SKP) as the catalyst, affording the corresponding 5,6,7,8-tetrahydro products in high chemoselectivities. This catalytic system is also effective for the asymmetric carbocycle hydrogenation of fused heteroarenes bearing a boryl or amino group. Experimental studies provided a strong support for the homogeneous nature of the catalysis, and an inner-sphere mechanism was proposed for the hydrogenation. DFT calculations indicated that the hydrogenation is initiated by η4-coordinative activation of quinoline carbocycle to Ru dihydride complex of SKP, followed by metal-to-ligand hydride transfer. Subsequent carbocycle reduction proceeds via consecutive steps of the H2 oxidative addition and C–H reductive elimination.

DOI: 10.1021/jacs.4c05365

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c05365