Highly Efficient Induction of Chirality in Intramolecular [2 + 2] Cycloadditions between Ketenimines and Imines
作者:Fernando P. Cossío、Ana Arrieta、Begoña Lecea、Mateo Alajarín、Angel Vidal、Fulgencio Tovar
DOI:10.1021/jo991826q
日期:2000.6.1
Highly stereocontrolled, intramolecular [2 + 2] cycloadditions between ketenimines and imines leading to 1,2-dihydroazeto[2, 1-b]quinazolines have been achieved. The source of stereocontrol is a chiral carbon atom adjacent either to the iminic carbon or nitrogen atom. In the first case, the stereocontrol stems from the preference for the axial conformer in the first transition structure. In the second
酮亚胺和亚胺之间高度立体控制的分子内[2 + 2]环加成反应导致了1,2-二氢氮杂并[2,1-b]喹唑啉的形成。立体控制的来源是与亚氨基碳原子或氮原子相邻的手性碳原子。在第一种情况下,立体声控制源于在第一过渡结构中偏爱轴向适形器。在第二种情况下,立体控制的起源在于所形成的CC键与对应于极性CX键的sigma轨道之间的双电子稳定相互作用,X为负电原子。这些模型可以扩展到其他相关系统,以预测此分子内反应中的立体化学结果。