Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan, 46241, Republic of Korea.
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) and Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea.
Angew Chem Int Ed Engl. 2017 Dec 18;56(51):16262-16266. doi: 10.1002/anie.201709162. Epub 2017 Nov 27.
Regioselective C4-, C5-, and di-alkenylations of pyrazoles were achieved. An electrophilic Pd catalyst generated by trifluoroacetic acid (TFA) and 4,5-diazafluoren-9-one (DAF) leads to C4-alkenylation, whereas KOAc and mono-protected amino acid (MPAA) ligand Ac-Val-OH give C5-alkenylation. A combination of palladium acetate, silver carbonate, and pivalic acid affords dialkenylation products. Annulation through sequential alkenylation, thermal 6π-electrocyclization, and oxidation gives functionalized indazoles. This comprehensive strategy greatly expands the range of readily accessible pyrazole and indazole derivatives, enabling useful regiodivergent C-H functionalization of pyrazoles and other heteroaromatic systems.
实现了吡唑的区域选择性 C4-、C5-和二烯基化。三氟乙酸 (TFA) 和 4,5-二氮杂芴-9-酮 (DAF) 生成的亲电 Pd 催化剂导致 C4-烯基化，而 KOAc 和单保护氨基酸 (MPAA) 配体 Ac-Val-OH 则导致 C5-烯基化。醋酸钯、碳酸银和特戊酸的组合提供了二烯基化产物。通过顺序烯基化、热 6π-电环化和氧化进行环化得到官能化的吲唑。这种综合策略大大扩展了易于获得的吡唑和吲唑衍生物的范围，实现了吡唑和其他杂芳环系统的有用的区域发散 C-H 官能化。
