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Iridium-Catalyzed Triborylation of 3-Substituted Indoles

Andrew S. Eastabrook A and Jonathan Sperry A B
+ Author Affiliations
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A School of Chemical Sciences, University of Auckland, 23 Symonds Street, Auckland 1142, New Zealand.

B Corresponding author. Email: j.sperry@auckland.ac.nz

Australian Journal of Chemistry 68(12) 1810-1814 https://doi.org/10.1071/CH15393
Submitted: 1 July 2015  Accepted: 29 July 2015   Published: 27 August 2015

Abstract

Readily available 3-substituted indoles undergo a one-pot iridium-catalyzed triborylation at the C2, C5, and C7 sites. 1H NMR analysis indicates borylation at C2 and C7 occurs first (no monoborylated product is observed), with the third borylation occurring as a separate, distinct step that is sterically directed to C5 by a combination of the substituent at C3 and the boronate at C7. The resulting tetrasubstituted indoles possess a substitution pattern that is cumbersome to prepare using existing methods.


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