Ring-closure reactions through intramolecular substitution of thiophenoxide by oxygen and nitrogen nucleophiles: simple stereospecific synthesis of 4,5-dihydroisoxazoles and 4,5-dihydropyrazoles
作者:Mariola Zielinska-Błajet、Rafał Kowalczyk、Jacek Skarżewski
DOI:10.1016/j.tet.2005.03.085
日期:2005.5
A new and simple method for the stereospecific synthesis of 3,5-disubstituted-4,5-dihydro-isoxazoles (chiral isoxazolines) from readily available oximes of chiral Michael adducts of thiophenol to chalcones is reported. An analogous reaction with the N-arylhydrazones of the Michael adduct gave nonracemic 1-(aryl)-3,5-diphenyl-4,5-dihydro-1H-pyrazoles (chiral pyrazolines), but these products are configurationally
报道了一种新的,简单的方法,该方法可以从苯硫酚的手性迈克尔加合物向查耳酮的易获得的肟中立体定向合成3,5-二取代的4,5-二氢-异恶唑(手性异恶唑啉)。与迈克尔加成物的N-芳基hydr类似的反应得到非外消旋的1-(芳基)-3,5-二苯基-4,5-二氢-1H-吡唑(手性吡唑啉),但是这些产物构型不稳定。合成的关键步骤是闭环反应,该反应通过噻吩氧化物的立体特异性分子内亲核取代而发生。