Palladium-catalyzed oxidative arylacetoxylation of alkenes: synthesis of indole and indoline derivatives

Abstract

A method for the oxidative arylacetoxylation of alkenes has been developed to synthesize indole and indoline derivatives from readily accessible substrates. The cinnamyl tethered anilines with picolinamide as a directing group provided 3-substituted indoles via intramolecular oxidative arylacetoxylation, and the 2-methyl substituted cinnamyl anilines furnished indoline derivatives with 3-position quaternary stereocenters in good to excellent yields via sequential intramolecular oxidative arylacetoxylation, hydrolysis and oxidation steps.

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

“…59 The presence of picolinamide as a directing group on Ncinnamylanilines 144 was fundamental for the formation of 3-substituted indoles 145 as the result of an arylacetoxylation domino process (Scheme 56). 60 Analogously, starting from 2-methyl-substituted N-cinnamylanilines, cyclization gave indoline derivatives 146 with a quaternary stereocenter at C-3. Also in this case, the reaction proceeds via arene palladation and subsequent alkene insertion.…”

Recent Development in Palladium-Catalyzed Domino Reactions: Access to Materials and Biologically Important Carbo- and Heterocycles

“…In the case of cinnamyl tethered anilines with a methyl substituent the isomerization was restricted and acetoxylation lead the indoline derivatives (Scheme 99). 151…”

“…In the case of cinnamyl tethered anilines with a methyl substituent, the isomerization was restricted and acetoxylation lead to the indoline derivatives (Scheme 99). 151 A previous example, recorded in Scheme 25, involved the formation of a C−O bond in the scope of the synthesis of benzosultams using a simple alkyne relay process.…”

Access to indolines from primary phenylethylamines by an unexpected palladium-catalyzed C–H functionalization process

“…It should be noted that palladium catalyzed oxidative synthesis of pyrrolidine, indole and indoline derivatives needs the presence of the picolinamide fragment as a directing group. 20,21…”