C2, C5, and C4 Azole N-Oxide Direct Arylation Including Room-Temperature Reactions
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- 作者：Louis-Charles Campeau ; Mé ; gan Bertrand-Laperle ; Jean-Philippe Leclerc ; Elisia Villemure ; Serge Gorelsky ; Keith Fagnou
- 刊名：Journal of the American Chemical Society
- 出版年：2008
- 出版时间：March 19, 2008
- 年：2008
- 卷：130
- 期：11
- 页码：3276 - 3277
- 全文大小：77K
- 年卷期：v.130,no.11(March 19, 2008)
- ISSN：1520-5126
文摘
The N-oxide group imparts a dramatic increase in reactivity at all positions of the azole ring of thiazoles and imidazoles and changes the weak bias for C5 > C2 arylation to a reliable C2 > C5 > C4 reactivity profile. Use of this cross-coupling strategy enables high yielding and room-temperature C2 arylations, mild reactions at C5, and the first examples of C4 arylation-providing a unique opportunity for exhaustive functionalization of the azole core with complete control of regioselectivity. A correlation of reactivity with the relative contributions of each carbon atom to the HOMO is observed and discussed.