端炔与对亚甲基苯醌的1,6-加成

为了合成selaginellin家族天然产物,我们开发了炔锂和对亚甲基苯醌的1,6-加成反应。研究了此反应的反应条件及底物适用范围和限制。结果表明,对亚甲基苯醌苯环上的取代基对反应速率和产率有显著的影响:吸电子基团增加其亲电性,使反应变快,并且可以得到较高的产率;与此相反,给电子基团则降低了对亚甲基苯醌的亲电性,反应变慢,并且表现出可逆性,产率变低。端炔对反应影响很小,均能得到高产率的产物。本方法可用于快速构建selaginellin家族天然产物的骨架结构。

1,6-Addition of Terminal Alkynes to p-Quinone Methides

In order to synthesize selaginellin family natural products, a methodology of 1,6-addition of alkynyl lithium to p-quinone methides was developed. The reaction conditions and scope and limitations of substrates of this reaction were investigated. The results show that the electronic effect of substituents on the phenyl ring of p-quinone methides exhibits significant effects on reaction rates and yields. Electro-withdrawing groups accelerate the addition and lead to good yields. On the other hand, electro-donating groups deactivate p-quinone methides, and low yield is observed presumably due to the equilibrium nature of the reaction. Besides, all alkynes surveyed provide corresponding products in high yield. This novel method can provide a rapid assembly of the skeleton of selaginellin natural products.