Photoredox-Catalyzed Intermolecular Hydroalkylative Dearomatization of Electron-Deficient Indole Derivatives

Abstract

Dearomatization of indole derivatives offers a straightforward approach to access diverse indolines. To date, the corresponding dearomative transformations involving electron-deficient indoles are limited. Herein, we report a one-electron strategy for dearomatization of electron-deficient indoles via a photoredox-catalyzed hydroalkylation employing commercially available glycine derivatives as the hydrofunctionalization reagents. Followed by DBU-mediated lactamization, structurally appealing lactam-fused indolines are obtained in good to excellent yields with exclusive selectivity.

Decatungstate‐Photocatalyzed Dearomative Hydroacylation of Indoles: Direct Synthesis of 2‐Acylindolines

“…developed an efficient organophotoredox‐catalyzed hydroalkylative dearomatization of C2‐ and C3‐substituted indoles using N ‐arylglycine derivatives as electron‐rich radical precursors. Lactams were obtained in high yields and complete diastereoselectivity after DBU‐mediated cyclization (Scheme 1, Equation (1)) [6] . One year later, Wang et al.…”

“…Lactams were obtained in high yields and complete diastereoselectivity after DBU-mediated cyclization (Scheme 1, Equation ( 1)). [6] One year later, Wang et al accomplished an elegant stereoselective hydroalkylation of electron-poor indoles bearing Oppolzer camphorsultam auxiliary with tertiary amines leading to various enantioenriched indolines in good yields with excellent diastereoselectivities (Scheme 1, Equation ( 2)). [7a] Later, the same group disclosed a diastereoselective dearomative hydro-functionalization of indoles through radical decarboxylation of a wide variety of aliphatic carboxylic acids (Scheme 1, Equation ( 3)).…”

Visible-light enabled synthesis of cyclopropane-fused indolines via dearomatization of indoles

“…Previously, we reported a visible-light induced dearomatization reaction of indole derivatives via a radical–radical coupling process. 11 Driven by our ongoing interest on this topic, we envisaged that photoredox-catalyzed radical addition-polar cyclization cascade would occur when other radical precursors were introduced. 9 f , g In this case, an efficient strategy for rapid access to cyclopropane-fused indolines might be developed.…”

Visible-light induced dearomatization reactions

“…Electron-deficient indole derivatives were feasible substrates for this strategy and the corresponding dearomatization reaction was also demonstrated by the authors (Scheme 52). 96 Structurally appealing lactam-fused indolines were obtained in good to excellent yields with exclusive selectivity.…”