New shelf-stable halo- and alkoxy-substituted pyridylboronic acids and their Suzuki cross-coupling reactions to yield heteroarylpyridines

Parry, P.R.; Bryce, M.R.; Tarbit, B.

Abstract

New shelf-stable pyridylboronic acids have been synthesized: bromine-lithium exchange followed by reaction with triiso-propylborate (TEPB) yielded 2-fluoro-5-pyridylboronic acid (4), 3-bromo-5-pyridylboronic acid (5) and 2-ethoxy-5-pyridylboronic acid (6); directed lithiation followed by reaction with trimethylborate (TMB) or TIPB afforded 2-methoxy-3-pyridylboronic acid (8), 3-bromo-6-methoxy-4-pyridylboronic acid (11) and 3-bromo-6-ethoxy-4-pyridylboronic acid (12). Cross-coupling of pyridylboronic acids 4, 6, 8, and 11 with 3-bromoquinoline [CS2CO3, Pd(PPh3)(2)Cl-2, 1,4-dioxane, 95 degreesC] gave pyridinylquinoline derivatives 13, 15-17 in 50-77% yields: the analogous reaction of 5 was low yielding due to further in situ reactions of the product 14. Cross-coupling of 12 with 2-bromo-5-nitrothiophene gave 3-bromo-4-(5-nitro-2-thienyl)-6-ethoxypyridine (18).

Citation

Parry, P., Bryce, M., & Tarbit, B. (2003). New shelf-stable halo- and alkoxy-substituted pyridylboronic acids and their Suzuki cross-coupling reactions to yield heteroarylpyridines. Synthesis: Journal of Synthetic Organic Chemistry, 1035-1038

• Journal Article Type: Article
• Publication Date: 2003-05
• Journal: Synthesis : journal of synthetic organic chemistry.
• Print ISSN: 0039-7881
• Publisher: Thieme Gruppe
• Peer Reviewed: Peer Reviewed
• Issue: 7
• Pages: 1035-1038