Department of Chemistry and Nano Science (BK Plus), Ewha Womans University , Seoul 120-750, Korea.
Org Lett. 2016 Dec 16;18(24):6432-6435. doi: 10.1021/acs.orglett.6b03328. Epub 2016 Dec 1.
A novel, one-pot route for the synthesis of nonaromatic ring-fused 1,4-oxazepines and 1,4-oxazines has been developed. The reaction features a sequential rhodium(II)-catalyzed reaction of N-sulfonyl-1,2,3-triazoles with glycidols, followed by a regioselective Lewis acid Mg(OBu)-catalyzed intramolecular ring-opening reaction. It has been found that the regioselectivity in the epoxide ring-opening was largely determined by the substituents on the glycidols. Thus, substituted glycidols (R ≠ H) afforded seven-membered oxazepine derivatives selectively, while unsubstituted glycidols (R = H) afforded six-membered oxazine derivatives. Plausible reaction pathways are elucidated and supported by experiments with several glycidols bearing different substituents around the epoxide functionality.
开发了一种新颖的、一锅法合成非芳环稠合 1,4-噁嗪和 1,4-恶唑啉的方法。该反应的特点是 Rh(II)催化 N-磺酰基-1,2,3-三唑与缩水甘油的顺序反应，然后是区域选择性路易斯酸 Mg(OBu)-催化的分子内环开反应。研究发现，环氧开环的区域选择性主要取决于缩水甘油上的取代基。因此，取代的缩水甘油（R ≠ H）可选择性地得到七元噁嗪衍生物，而未取代的缩水甘油（R = H）则得到六元噁嗪衍生物。通过对几种带有不同取代基的环氧功能基的缩水甘油进行实验，阐明了合理的反应途径并提供了支持。
