Studies of stereoselectivity in cycloaddition of cyclic dienes to 2-azabicyclo[2.2.2]octene derivatives; through-space effects on 15N NMR shifts of bicyclic amines and lactams
作者:John R Malpass、Djaballah Belkacemi、David R Russell
DOI:10.1016/s0040-4020(01)01125-5
日期:2002.1
2.2]oct-7-en-3-one 7 are observed, giving exo,endo- and endo,endo-Diels–Alder cycloadducts 10a and 11a at atmospheric pressure (exo- and endo-defined here by reference to the benzo- and etheno-bridges, respectively). Hydride reduction of the carbonyl in 10a provides an indirect route to 9, which is formally derived from 2-methyl-5,6-benzo-2-azabicyclo[2.2.2]oct-7-ene 6 but which is inaccessible directly
在2-甲基-5,6-苯并-2-氮杂双环[2.2.2] oct-7-en-3-one 7中,环己-1,3-二烯与双键形成双键的四种可能的面方法中只有7种观察到,给予外,内切-和内型,内切-Diels -阿尔德cycloadducts 10A和11A在大气压力(外-和内分别这里-defined通过参考苯并和亚乙烯基桥)。10a中羰基的氢化物还原提供了通往9的间接途径,该途径正式衍生自2-甲基-5,6-苯并-2-氮杂双环[2.2.2] oct-7-ene 6但由于6的热逆加成,因此无法直接访问。X射线晶体结构证实了立体化学分配。环戊二烯与7的环加成反应遵循相似的路径,并将结果与仅观察到面部外侵的7-氮杂双环[2.2.1]庚烯类似物的相应研究进行比较。与邻近的乙烯桥和乙醇桥的空间相互作用引起氨基和内酰胺氮的大量高场15 N NMR位移。