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Acyl‐Directed ortho ‐Borylation of Anilines and C7 Borylation of Indoles using just BBr 3
Author(s) -
Iqbal Saqib A.,
Cid Jessica,
Procter Richard J.,
Uzelac Marina,
Yuan Kang,
Ingleson Michael J.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201909786
Subject(s) - borylation , chemistry , pinacol , electrophile , moiety , functional group , combinatorial chemistry , selectivity , stereochemistry , organic chemistry , aryl , catalysis , alkyl , polymer
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 BBr 3 . 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.