Palladium-Catalyzed Direct Heck Arylation of Dual π-Deficient/π-Excessive Heteroaromatics. Synthesis of C-5 Arylated Imidazo[1,5-a]pyrazines
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- 作者：Jian-Xin Wang ; J. Adam McCubbin ; Meizhong Jin ; Radoslaw S. Laufer ; Yunyu Mao ; Andrew P. Crew ; Mark J. Mulvihill ; Victor Snieckus
- 刊名：Organic Letters
- 出版年：2008
- 出版时间：July 17, 2008
- 年：2008
- 卷：10
- 期：14
- 页码：2923 - 2926
- 全文大小：175K
- 年卷期：v.10,no.14(July 17, 2008)
- ISSN：1523-7052
文摘
A general and efficient synthesis of 5-aryl imidazo[1,5-a]pyrazines by palladium-catalyzed coupling of the corresponding 8-substituted derivatives with aryl halides is described. The scope of this new reaction for the imidazo[1,5-a]pyrazine ring system was explored using three readily available 8-substituted precursors, X = NH2, NMe2, and OMe, as well as 8-aryl derivatives, X = Ar′. On the basis of these results as well as studies using a deuterated derivative, a Heck-like mechanism is proposed for this transformation.