The reactions of salicylaldimines with electron‐rich alkenes (2,3‐dihydro‐2H‐furan and 3,4‐dihydro‐2H‐pyran) catalyzed by N,N′‐dioxide–Sc(OTf)3complexes were investigated. The methodology was successfully applied to the asymmetricsynthesis of cis‐4‐aminobenzopyran derivatives. Excellent yields, diastereo‐ and enantioselectivities were observed for a broad range of substrates under mild conditions
A stereoselective synthesis of symmetrical and unsymmetrical bibenzo[e][1,3]oxazine-2,2′-dione derivatives induced by low-valent titanium reagent
作者:Guo-Lan Dou、Fang Sun、Da-Qing Shi
DOI:10.1016/j.tet.2012.03.122
日期:2012.6
unsymmetrical bibenzo[e][1,3]oxazine-2,2′-dionederivatives were synthesized by the reaction of various o-hydroxy Schiff bases and triphosgene induced by low-valenttitanium reagent (TiCl4/Sm). A variety of substrates can participate in the process with good yields. The present method provides a useful preparation of 3,3′,4,4′-tetrahydro-4,4′-bibenzo[e][1,3]oxazine-2,2′-dionederivatives, which cannot be
低价钛试剂(TiCl 4 / Sm)诱导的各种邻羟基席夫碱与三光气反应合成了一系列对称和不对称的联苯并[ e ] [1,3]恶嗪-2,2'-二酮衍生物。)。多种底物可以高收率参与该过程。本方法提供了有用的3,3',4,4'-四氢-4,4'-联苯并[ e ] [1,3]恶嗪-2,2'-二酮衍生物的制备方法,否则无法制备。反应的机理表明一锅参与还原,偶联和环化。