Direct Synthesis of Previously Inaccessible Bridgehead Azabicyclics by Intramolecular Cyclization of α-Sulfonamido and α-Sulfonimido Radicals
作者:Leo A. Paquette、Choon Sup Ra、Jeffrey D. Schloss、Silvana M. Leit、Judith C. Gallucci
DOI:10.1021/jo010216z
日期:2001.5.1
Syntheses of the first bridgehead sultams and the only known bridgehead disulfonimide are described. Both approaches capitalize on the electrophilicity of alpha-sulfonyl radicals and their propensity to undergo intramolecular ring closure. Where double bonds are concerned, 5-exo and 6-exo pathways operate preferentially as long as structural strain is not excessive. When the reaction center is a carbon-carbon
描述了第一个桥头磺胺和唯一已知的桥头二磺酰亚胺的合成。两种方法都利用了α-磺酰基的亲电性和它们进行分子内闭环的倾向。在涉及双键的情况下,只要结构应变不过度,5-exo和6-exo途径就优先起作用。当反应中心是碳-碳三键时,第一个环化反应会产生乙烯基,该乙烯基具有足够的反应活性以捕获溶剂苯。在45的情况下,该顺序反应重要地导致引入足够活化的苯乙烯官能团以允许第二个闭环在动力学上可行。通过X射线晶体学方法已经阐明了12和17的固态结构特征。尽管与氮孤对相对于相邻磺酰基的排列方式的规范存在重大差异,但这些化合物仍具有良好的水解稳定性。对于13,可能产生α-磺酰胺碳负离子,并且已经实现了用乙酸铬酰的区域特异性氧化。