Acyl‐Directed ortho‐Borylation of Anilines and C7 Borylation of Indoles using just BBr3. (12th September 2019)

• Record Type: Journal Article
• Authors: Iqbal, Saqib A.; Cid, Jessica; Procter, Richard J.; Uzelac, Marina; Yuan, Kang; Ingleson, Michael J.
• Is Part Of: Angewandte Chemie. Volume 131:Number 43(2019)
• Page Start: 15525
• Page End: 15529
• Publication Date: 2019-09-12
• Subjects: Borane -- Borenium -- Borylierung -- Dirigierende Gruppen -- Elektrophile aromatische Substitution; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201909786
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Indoles are privileged heterocycles found in many biologically active pharmaceuticals and natural products. However, the selective functionalization of the benzenoid moiety in indoles in preference to the more reactive pyrrolic unit is a significant challenge. Herein we report that N‐acyl directing groups enable the C7‐selective C−H borylation of indoles using just BBr3 . This transformation shows some functional‐group tolerance and notably proceeds with C6 substituted indoles. The directing group can be readily removed in situ and the products isolated as the pinacol boronate esters. Acyl‐directed electrophilic borylation can be extended to carbazoles and anilines with excellent ortho selectivity. 4‐amino‐indoles are amenable to this process, with acyl group installation and directed electrophilic C−H borylation enabling selective formation of C5‐BPin‐indoles. Abstract : B‐dirigiert : Eine Acyl‐dirigierte elektrophile C‐H‐Borylierung bietet Zugang zu neuartigen C5‐ und C7‐borylierten Indolen mit lediglich BBr3 als Borylierungsreagens. Die Umwandlung verläuft über die Bildung von sechsgliedrigen Boracyclen.