Iridium-catalyzed C–H borylation of pyridines

Sadler, S.A.; Tajuddin, H.; Mkhalid, I.A.I.; Batsanov, A.S.; Albesa-Jove, D.; Cheung, M.S.; Maxwell, A.C.; Shukla, L.; Roberts, B.; Blakemore, D.C.; Lin, Z.; Marder, T.B.; Steel, P.G.

doi:10.1039/c4ob01565g

Iridium-catalyzed C–H borylation of pyridines

Sadler, S.A.; Tajuddin, H.; Mkhalid, I.A.I.; Batsanov, A.S.; Albesa-Jove, D.; Cheung, M.S.; Maxwell, A.C.; Shukla, L.; Roberts, B.; Blakemore, D.C.; Lin, Z.; Marder, T.B.; Steel, P.G.

Authors

S.A. Sadler

H. Tajuddin

I.A.I. Mkhalid

A.S. Batsanov

D. Albesa-Jove

M.S. Cheung

A.C. Maxwell

L. Shukla

B. Roberts

D.C. Blakemore

Z. Lin

T.B. Marder

Professor Patrick Steel p.g.steel@durham.ac.uk
Professor

Abstract

The iridium-catalysed C–H borylation is a valuable and attractive method for the preparation of aryl and heteroaryl boronates. However, application of this methodology for the preparation of pyridyl and related azinyl boronates can be challenged by low reactivity and propensity for rapid protodeborylation, particularly for a boronate ester ortho to the azinyl nitrogen. Competition experiments have revealed that the low reactivity is due to inhibition of the active catalyst through coordination of the azinyl nitrogen lone pair at the vacant site on the iridium. This effect can be overcome through the incorporation of a substituent at C-2. Moreover, when this is sufficiently electron-withdrawing protodeborylation is sufficiently slowed to permit isolation and purification of the C-6 boronate ester. Following functionalization, reduction of the directing C-2 substituent provides the product arising from formal ortho borylation of an unhindered pyridine ring.

Citation

Sadler, S., Tajuddin, H., Mkhalid, I., Batsanov, A., Albesa-Jove, D., Cheung, M., …Steel, P. (2014). Iridium-catalyzed C–H borylation of pyridines. Organic and Biomolecular Chemistry, 12(37), 7318-7327. https://doi.org/10.1039/c4ob01565g

Journal Article Type	Article
Acceptance Date	Aug 1, 2014
Online Publication Date	Aug 1, 2014
Publication Date	Oct 7, 2014
Deposit Date	Sep 26, 2014
Publicly Available Date	Sep 30, 2014
Journal	Organic and Biomolecular Chemistry
Print ISSN	1477-0520
Electronic ISSN	1477-0539
Publisher	Royal Society of Chemistry
Peer Reviewed	Peer Reviewed
Volume	12
Issue	37
Pages	7318-7327
DOI	https://doi.org/10.1039/c4ob01565g