Chemoselective Amination of 5-Bromo-2-chloro-3-fluoropyridine

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• 作者：Bryan W. Stroup ; Paul V. Szklennik ; Cornelia J. Forster ; Michael H. Serrano-Wu
• 刊名：Organic Letters
• 出版年：2007
• 出版时间：May 10, 2007
• 年：2007
• 卷：9
• 期：10
• 页码：2039 - 2042
• 全文大小：69K
• 年卷期：v.9,no.10(May 10, 2007)
• ISSN：1523-7052

文摘

The chemoselective functionalization of 5-bromo-2-chloro-3-fluoropyridine (1c) is described. Catalytic amination conditions (Pd₂dba₃, Xantphos,base) afford exclusively the bromide substitution product (2) for both secondary amines and primary anilines. A reversal in chemoselectivityis observed under neat conditions in the absence of palladium catalysis, with substitution at the 2-chloro position preferred to generate 3.Last, selective substitution of the 3-fluoro group is achieved under S_NAr conditions to afford the dihalo adduct (4).