Amy E. Smith, Kate M. Clapham, A. Batsanov
Mar 1, 2008
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0
Influential Citations
23
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Journal
European Journal of Organic Chemistry
Abstract
We report the synthesis of (2,6-dimethoxy-3-pyridyl)boronic acid (2), (2,3-dimethoxy-4-pyridyl)boronic acid (4), (2,6-difluoro-3-pyridyl)boronic acid (6), (2,6-dichloro-3-pyridyl)boronic acid (8) and (2,3-dichloro-4-pyridyl)boronic acid (10) by directed ortho-metalation reactions on the corresponding disubstituted pyridine precursor, followed by the reaction with triisopropyl borate (TPB) or trimethyl borate. Thereactivity of the pyridylboronic acids with heteroaryl halides in Suzuki–Miyaura cross-coupling reactions has been evaluated. New highly functionalized heteroarylpyridine derivatives have thereby been obtained in moderate to high yields. The reaction of 8 and 3-amino-2-chloropyridine yielded the rare 5H-pyrrolo[2,3-b:4,5-b′]dipyridine (i.e. 1,5-diazacarbazole) ring system by sequential cross-coupling and intramolecular cyclisation reactions. The X-ray crystal structures are reported for the pyridylboronic acids 2, 4, 8 and 10. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)