α-Cyclization of tertiary amines. Part 3. Captodative or push-pull enamines form pyrrolines, pyrrolizidines and their ring homologues with dimethyl acetylenedicarboxylate in a highly diastereoselective reaction
作者:Benoît De Boeck、Shuiping Jiang、Zdenek Janousek、Heinz G. Viehe
DOI:10.1016/s0040-4020(01)85235-2
日期:1994.1
The title one-pot reaction occurs through a sequence of [2+2] cycloaddition, ring opening to dienamines and formation of a 1,5-dipole by [1,6] hydrogen-shift. This intermediate may cyclize or, in sterically suitable cases and at lower temperatures, lead to isolable N-vinyl enamines by proton transfer.
通过[2 + 2]环加成,二烯胺开环和通过[1,6]氢转移形成1,5-偶极的过程发生标题一锅反应。该中间体可环化,或在空间上合适的情况下且在较低温度下通过质子转移产生可分离的N-乙烯基烯胺。