Synthesis of meta-(Indol-3-yl)phenols from Indoles and Cyclohexenone via Palladium(II)-Catalyzed Oxidative Heck Reaction and Dehydrogenative Aromatization in a One-Step Sequence

Abstract

Facile construction of a meta-(indol-3-yl)phenol framework with a wide substrate scope (a total of 25 compounds) via a palladium(II)-catalyzed oxidative Heck reaction and dehydrogenative aromatization in a one-step sequence is reported. This methodology affords a novel route for the privileged structures that are challenging to access via a direct link between indole and phenol, in a highly efficient and atom-economical manner.

Pd-catalyzed direct functionalization of glycals with cycloalkenones: application to the synthesis of chiral phenanthrenones

“…Cycloalkenones are commercially available reagents and have been demonstrated as an excellent substrate in cross-dehydrogenative coupling reactions under Pd-catalysis. [22][23][24][25] In particular, oxidative Heck reactions of cycloalkenones with aryl boronic acids/halides and indoles are well studied and applied in the synthesis of valuable products. The synthesis of b-substituted cyclohexenone by Pdmediated cross-coupling reactions of aryl boronic acids/halides and cyclohexenones followed by aerobic dehydrogenative aromatization was studied by Stahl and others.…”

“…24 In the Kim reaction conditions, oxidative Heck followed by dehydrogenative aromatization by using O 2 as a sole oxidant directly provides the required meta-(indol-3-yl) phenols in one step (Scheme 1d). 25 Phenanthrenones are known to have wide biological activities and some of the biologically potent phenanthrenones of plant origin are listed in Fig. 1.…”

“…24 In the Kim reaction conditions, oxidative Heck followed by dehydrogenative aromatization by using O 2 as a sole oxidant directly provides the required meta -(indol-3-yl) phenols in one step (Scheme 1d). 25…”

LiBr-Catalyzed C3-Disulfuration between Indole and N-Dithiophthalimide

“…The significance of indole derivatives in the treatment of diseases has been increasingly prominent in recent years, and the direct C3-functionalization or directing group-assisted C2-functionalization of indole is the typical strategy for the preparation of these molecules . Many achievements were acquired in the cyanation, sulfenylation, and halogenation in the C3-position of indoles in the past few years; however, the disulfide method of indole 3-position was rarely reported.…”