Pd(II)-Catalyzed Transient Directing Group-Assisted Regioselective Diverse C4–H Functionalizations of Indoles
Anurag Singh, Arnab Dey, Kuntal Pal, Om Prakash Dash, Chandra M. R. Volla
Abstract
The development of a rational strategy for achieving site-selective C4–H halogenation of indoles is an appealing yet challenging task. Herein, we disclose a Pd(II)-catalyzed transient directing group (TDG)-assisted methodology for realizing C4 chlorination/bromination of indoles employing glycine as the TDG and NFSI as a bystanding oxidant. The use of inexpensive and commercially available CuX2 as the halide source is the key highlight of this protocol. Furthermore, the TDG methodology was also extended to accessing C4 acetoxylated indoles employing acetic acid as the acetate source and 1-fluoro-2,4,6-trimethylpyridinium triflate as the oxidant.
Topics & Concepts
HalogenationChemistryRegioselectivityTrifluoromethanesulfonateAcetic acidHalideCatalysisCombinatorial chemistryOrganic chemistryCatalytic C–H Functionalization MethodsSynthesis and Catalytic ReactionsOxidative Organic Chemistry Reactions