Chen Bo, Zhang Lei, Luo Huihui, Huang Liang, He Peipei, Xue Gaijun, Liang Hongliang, Dai Wen
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China.
JACS Au. 2023 Jan 13;3(2):476-487. doi: 10.1021/jacsau.2c00608. eCollection 2023 Feb 27.
The oxidative cleavage and functionalization of unsaturated C-C bonds are important processes for synthesis of carbonyl compounds from hydrocarbon feedstocks, yet there has been no report of direct amidation of unsaturated hydrocarbons an oxidative cleavage of unsaturated C-C bonds with molecular oxygen as an environmentally benign oxidant. Herein, for the first time, we describe a manganese oxide-catalyzed auto-tandem catalysis strategy that enables direct synthesis of amides from unsaturated hydrocarbons by coupling oxidative cleavage with amidation. With oxygen as an oxidant and ammonia as a nitrogen source, a wide range of structurally diverse mono- and multisubstituted activated and unactivated alkenes or alkynes can smoothly undergo unsaturated C-C bond cleavage to deliver one- or multiple-carbon shorter amides. Moreover, a slight modification of the reaction conditions also allows for the direct synthesis of sterically hindered nitriles from alkenes or alkynes. This protocol features excellent functional group tolerance, a broad substrate scope, flexible late-stage functionalization, facile scalability, and a cost-effective and recyclable catalyst. Detailed characterizations reveal that the high activity and selectivity of the manganese oxides are attributed to the large specific surface area, abundant oxygen vacancies, better reducibility, and moderate acid sites. Mechanistic studies and density functional theory calculations indicate that the reaction proceeds through divergent pathways depending on the structure of substrates.
不饱和碳 - 碳键的氧化裂解和官能团化是从烃类原料合成羰基化合物的重要过程，然而，尚未有关于以分子氧作为环境友好型氧化剂，对不饱和烃进行直接酰胺化以及不饱和碳 - 碳键氧化裂解的报道。在此，我们首次描述了一种氧化锰催化的自动串联催化策略，该策略能够通过氧化裂解与酰胺化的偶联，从不饱和烃直接合成酰胺。以氧气作为氧化剂，氨作为氮源，多种结构多样的单取代和多取代的活化和未活化烯烃或炔烃能够顺利地进行不饱和碳 - 碳键裂解，生成少一个或多个碳的酰胺。此外，对反应条件进行轻微调整，也能够从烯烃或炔烃直接合成位阻腈。该方法具有出色的官能团耐受性、广泛的底物范围、灵活的后期官能团化、易于放大以及具有成本效益且可循环使用的催化剂。详细表征表明，氧化锰的高活性和选择性归因于其大比表面积、丰富的氧空位、更好的还原性和适度的酸位点。机理研究和密度泛函理论计算表明，反应根据底物结构通过不同途径进行。
