Synthesis of Substituted Imidazo[1,5-a]pyrazines via Mono-, Di-, and Directed Remote Metalation Strategies

详细信息    查看全文

• 作者：Johnathan Board ; Jian-Xin Wang ; Andrew P. Crew ; Meizhong Jin ; Kenneth Foreman ; Mark J. Mulvihill ; Victor Snieckus
• 刊名：Organic Letters
• 出版年：2009
• 出版时间：November 19, 2009
• 年：2009
• 卷：11
• 期：22
• 页码：5118-5121
• 全文大小：189K
• 年卷期：v.11,no.22(November 19, 2009)
• ISSN：1523-7052

文摘

Imidazo[1,5-a]pyrazines 1 undergo regioselective C3-metalation and C5/C3-dimetalation to afford a range of functionalized derivatives 2a−2g (Table 1), and 4a−4d (Table 2). Under similar conditions, the C3-methyl derivatives 2a and 5 undergo surprising regioselective C5-deprotonation to afford, after electrophile quench, products 4b and 6a−6p (Table 3), results that are rationalized by quantum mechanical calculations. Benzamide 7b, obtained from such metalation chemistry followed by Suzuki cross coupling, undergoes directed remote metalation-cyclization to afford 8, representing the hitherto unknown triazadibenzo[cd,f]azulen-7(6H)-one tricyclic ring system.