Selective ortho and benzylic functionalization of secondary and tertiary p-tolylsulfonamides.: Ipso-bromo desilylation and Suzuki cross-coupling reactions
Selective ortho and benzylic functionalization of secondary and tertiary p-tolylsulfonamides.: Ipso-bromo desilylation and Suzuki cross-coupling reactions
复制标题
DOI：
10.1021/jo001402s
复制
发表时间：
2001-06-01
影响因子：
3.6
通讯作者：
Snieckus, V
中科院分区：
文献类型：
--
作者：
MacNeil, SL;Familoni, OB;Snieckus, V
使用正丁基锂对二级和三级磺酰胺 1 和 2 进行了动力学与热力学去质子化研究。虽然 1 和 2 都显示出动力学邻位金属化，但热力学条件分别导致邻位和苄基去质子化（图 1 和 2）。使用 n-BuLi/KOtBu 超碱对 1 进行金属化导致区域选择性苄基金属化（图 4）； LDA 去质子化也进行了简要探讨。应用所开发的条件可以合成多种磺酰胺产品 5a-e、6a-e、7a、b 和 8a-e。异溴脱甲硅烷基化反应得到磺酰胺9a、b，而Suzuki交叉偶联反应得到联芳基磺酰胺11a-c。
Kinetic vs thermodynamic deprotonation studies on secondary and tertiary sulfonamides 1 and 2 using n-BuLi have been carried out. While both 1 and 2 show kinetic ortho-metalation, thermodynamic conditions lead to ortho and benzylic deprotonation, respectively (Figures 1 and 2). Metalation of 1 using the n-BuLi/KOtBu superbase led to regioselective benzylic metalation (Figure 4); LDA deprotonation was also briefly explored. Application of the developed conditions allows the synthesis of diverse sulfonamide products 5a-e, 6a-e, 7a,b, and 8a-e. Ipso-bromo desilylation reactions afford sulfonamides 9a,b while Suzuki cross-coupling reactions furnish biaryl sulfonamides 11a-c.