Synthesis of Substituted Imidazo[1,5-<i>a</i>]pyrazines via Mono-, Di-, and Directed Remote Metalation Strategies
作者:Johnathan Board、Jian-Xin Wang、Andrew P. Crew、Meizhong Jin、Kenneth Foreman、Mark J. Mulvihill、Victor Snieckus
DOI:10.1021/ol901889e
日期:2009.11.19
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
咪唑并[1,5- a ]吡嗪1经历区域选择性的C3-金属化和C5 / C3-双金属化,从而提供一系列功能化的衍生物2a - 2g(表1)和4a - 4d(表2)。在相似的条件下,C3-甲基衍生物2a和5经历令人惊讶的区域选择性C5-去质子化,在亲电淬灭后得到产物4b和6a - 6p(表3),该结果通过量子力学计算得以合理化。苯甲酰胺7b得自这种金属化化学方法,随后是铃木交叉偶联的S -C,经定向远程金属化-环化,得到8,代表迄今未知的三氮杂二苯并[ cd,f ] azulen -7(6 H)-一个三环系统。