Photochemical Approach to the Cyclohepta[b]indole Scaffold by Annulative Two‐Carbon Ring‐Expansion. Issue 52 (17th August 2020)

• Record Type: Journal Article
• Authors: Tymann, Dina Christina; Benedix, Lars; Iovkova, Lyuba; Pallach, Roman; Henke, Sebastian; Tymann, David; Hiersemann, Martin
• Is Part Of: Chemistry. Volume 26:Issue 52(2020)
• Page Start: 11974
• Page End: 11978
• Publication Date: 2020-08-17
• Subjects: cascade reactions -- cyclohepta[b]indole -- indole[2, 3-d]tropone -- photochemistry -- ring expansion; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202002581
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We report on the implementation of the concept of a photochemically elicited two‐carbon homologation of a π‐donor–π‐acceptor substituted chromophore by triple‐bond insertion. Implementing a phenyl connector between the slide‐in module and the chromophore enabled the synthesis of cylohepta[ b ]indole‐type building blocks by a metal‐free annulative one‐pot two‐carbon ring expansion of the five‐membered chromophore. Post‐irradiative structural elaboration provided founding members of the indolo[2, 3‐ d ]tropone family of compounds. Control experiments in combination with computational chemistry on this multibond reorganization process founded the basis for a mechanistic hypothesis. Abstract : By enabling cooperativity of substituent and solvent effects, the concept of a photochemically triggered two‐carbon ring expansion was implemented to open a modular synthetic access to cyclohepta[ b ]indole‐type buildings blocks (see scheme).