New Shelf-Stable Halo- and Alkoxy-SubstitutedPyridylboronic Acids and their Suzuki Cross-Coupling Reactions toYield Heteroarylpyridines

Autor:	Paul R. Parry, Martin R. Bryce, Brian Tarbit
Rok vydání:	2003
Předmět:	chemistry.chemical_compound Yield (engineering) Suzuki reaction Chemistry Organic Chemistry Pyridine Alkoxy group Medicinal chemistry Catalysis Coupling reaction
Zdroj:	Synthesis. 2003:1035-1038
ISSN:	1437-210X 0039-7881
DOI:	10.1055/s-2003-39158
Popis:	New shelf-stable pyridylboronic acids have been synthesized: bromine-lithium exchange followed by reaction with triiso-propylborate (TIPB) 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 TIPS 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 [CS 2 CO 3 , Pd(PPh 3 ) 2 Cl 2 , 1,4-dioxane, 95 °C] 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).
Databáze:	OpenAIRE
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