在亚胺和磺酰氯的磺胺-施陶丁格环加成中,环选择性主要受磺酰氯的α-取代基的电子效应和亚胺的亲核性控制。具有弱给电子和吸电子取代基的磺酰氯更喜欢[2 s +2 i ]环,形成顺式和反式-β-杜鹃花的混合物。带有强吸电子α-取代基的磺酰氯根据亚胺的亲核性表现出不同的年环选择性,具体如下:(1)取代基比甲基大的弱亲核亚胺仅经历[2 s +2 i ]环化反应,生成反式-β-杜鹃花;(2)具有N-甲基取代基的强亲核亚胺通常同时发生[2 s +2 i ]和[2 s +2 i +2 i ]环化反应,从而传递反式-β-杜鹃花和rel(3 S,5 S由一分子的亚砜和两分子的亚胺组成的,6 R)-1,2,4-噻二嗪烷1,1-二氧化物; (3)更强的亲核环状(Z)-亚胺主要产生[2 s +2 i +2 i ]环,产生一对非对映异构体[2 s +2i +2 i ]年环过氧化物1,2,4-噻二嗪烷1,1-二氧化物。
Selective imine formation from alcohols and amines catalyzed by polymer incarcerated gold/palladium alloy nanoparticles with molecular oxygen as an oxidant
Carbon black stabilized, polymer incarcerated gold/palladium alloy nanoparticles (PICB-Au/Pd) act as an efficient, reusable heterogeneous catalyst for imine synthesis from alcohols and amines through a tandem oxidative process using molecular oxygen as the terminal oxidant.
Syntheses of β-lactams from acetic acids and imines induced by phenyl dichlorophosphate reagent
作者:Ana Arrieta、Fernando P. Cossio、Claudio Palomo
DOI:10.1016/s0040-4020(01)96484-1
日期:——
Among the reagents known to produce β-lactams from imines and acetic acids, only phenyl dichlorophosphate and 1-methyl-2-chloropyridinium iodide are suitable for the synthesis of vinylamino- β-lactams. Reaction of acetic acids with ethanolimine derivatives promoted by phenyl dichlorophosphate affords oxazolidines instead β-lactams. Protection of the hydroxyl group as the trimethylsilyl ether in the