2-Ethoxy-3-pyridylboronic acid: A versatile reagent for the synthesis of highly-functionalised 3-aryl/heteroaryl-pyridines via Suzuki cross-coupling reactions

THOMPSON A., BATSANOV A., BRYCE M., Saygili N., PARRY P., TARBIT B.

TETRAHEDRON, vol.61, no.21, pp.5131-5135, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 61 Issue: 21
  • Publication Date: 2005
  • Doi Number: 10.1016/j.tet.2005.02.070
  • Journal Name: TETRAHEDRON
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.5131-5135
  • Hacettepe University Affiliated: Yes

Abstract

This paper describes the commercially-viable synthesis and isolation of 2-ethoxy-3-pyridylboronic acid on a ca. 70 g scale via a directed ortho-metalation reaction on readily-available 2-ethoxypyridine. A range of efficient cross-coupling reactions of 2-ethoxy-3-pyridylboronic acid with selected aryl/heteroaryl halides under palladium-catalysed Suzuki-Miyaura conditions yield novel 2-ethoxy-3-aryl/heteroaryl-pyridines in high yield (heteroaryl=pyridyl, pyrimidyl, pyrazyl). The X-ray crystal structure of 2-ethoxy-3-pyridylboronic acid reveals that the boronic acid group takes part in an intramolecular O-(HO)-O-... bond with the adjacent ethoxy substituent, and an intermolecular O-(HN)-N-... bond. (c) 2005 Elsevier Ltd. All rights reserved.