Pyrrole as a Directing Group: Regioselective Pd(II)-Catalyzed Alkylation and Benzylation at the Benzene Core of 2-Phenylpyrroles
作者:Johannes M. Wahl、Alexander Pöthig、Thorsten Bach
DOI:10.1021/acs.orglett.6b00141
日期:2016.2.19
Pyrrole has been employed for the first time as a directing group in the Pd(II)-catalyzed ortho-functionalization of C(sp2)–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
吡咯首次被用作 Pd(II) 催化的 C(sp 2 )-H 键的邻位官能化中的导向基团。各种取代的 2-苯基吡咯在苯环的邻位成功地甲基化、烷基化或苄化,产生各自的 2-取代的吡咯-2-基苯(36 个例子,51-93% 的产率)。进行该反应既不需要添加剂也不需要额外的配体,该反应通常以PdBr 2作为催化剂和Li 2 CO 3作为碱进行。从机制上讲,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。