作者:Alan R. Katritzky、Ion Ghiviriga、Ke Chen、Dmytro O. Tymoshenko、Ashraf A. A. Abdel-Fattah
DOI:10.1039/b008196p
日期:——
Novel polysubstituted 5,6-dihydro-4H-1,3-oxazines are synthesized by 1,4-cycloaddition of unactivated olefins with N-acyliminiums from benzotriazole precursors. The configuration and conformation of the products are deduced from NMR investigation. The regio- and exo–endo stereochemistry of the cycloaddition are discussed. Conformations of compounds of six types of substitution (6-mono; 6,6-, 5,6- and 4,6-di; 4,6,6- and 4,5,6-tri) are rationalized on the basis of axial-1,3-repulsion and the anomeric effect.
新型多取代的5,6-二氢-4H-1,3-恶嗪是通过未活化的烯烃与来自苯并三唑前体的N-酰基亚胺鎓进行1,4-环加成反应合成的。通过NMR研究推断产物的构型和构象。讨论了环加成的区域和外-内立体化学。基于轴向1,3-排斥和异头效应,对六种取代类型(6-单;6,6-、5,6-和4,6-二;4,6,6-和4,5,6-三)的化合物的构象进行了合理化解释。