Pyrrole as a Directing Group: Regioselective Pd(II)-Catalyzed Alkylation and Benzylation at the Benzene Core of 2-Phenylpyrroles.
Pyrrole as a Directing Group: Regioselective Pd(II)-Catalyzed Alkylation and Benzylation at the Benzene Core of 2-Phenylpyrroles.
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DOI：
10.1021/acs.orglett.6b00141
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发表时间：
2016-02
期刊：
影响因子：
5.2
通讯作者：
J. Wiest;Alexander Poethig;T. Bach
中科院分区：
文献类型：
--
作者：
J. Wiest;Alexander Poethig;T. Bach
吡咯首次被用作Pd（II）催化的C（sp（2））-H键邻位官能化反应中的导向基团。各种取代的2-苯基吡咯在苯环的邻位成功地被甲基化、烷基化或苄基化，得到相应的2-取代的吡咯-2-基苯（36个实例，51-93%产率）。进行该反应既不需要添加剂也不需要另外的配体，该反应常规地用PdBr 2作为催化剂和Li 2CO 3作为碱进行。从机理上讲，有证据表明钯与吡咯的预配位能够实现区域选择性邻位攻击。
Pyrrole has been employed for the first time as a directing group in the Pd(II)-catalyzed ortho-functionalization of C(sp(2))-H bonds. A variety of substituted 2-phenylpyrroles were successfully methylated, alkylated, or benzylated in the ortho-position of the benzene ring, yielding the respective 2-substituted pyrrol-2-yl benzenes (36 examples, 51-93% yield). Neither additives nor additional ligands were required to perform the reaction, which was routinely conducted with PdBr2 as the catalyst and Li2CO3 as the base. Mechanistically, there is evidence that precoordination of palladium to the pyrrole enables the regioselective ortho-attack.