N-Phosphoryl imines react with oxygenated dienes in the presence of Lewis acids to provide either the formal aza-Diels-Alder adduct, or the acyclic Mannich-type addition product, depending upon the catalyst and work up used, which is in agreement with the hypothesis that these reactions are mediated by zwitterionic Lewis acid-complex intermediates, rather than a concerted cycloaddition transition-state followed by hydrolytic ring opening. Stoichiometric asymmetric induction can be achieved using a zinc(II)-binol complex, producing up 77% ee.
N-
磷酰亚胺在
路易斯酸存在下与氧杂二烯反应,得到的产物取决于所用的催化剂和工作条件,可能是形式上的氮杂-狄尔斯-阿德尔加合物,或是无环的曼尼希型加成产物,这与反应通过两性离子
路易斯酸配合物中间体来介导的假设一致,而不是通过协同环加成过渡态再经
水解开环来进行的。使用
锌(II)-二
萘并联
苯酚配合物可以实现
化学计量的不对称诱导,产物的对映体过量率可达到77%。