An Expedient Phosphine-Catalyzed [4 + 2] Annulation: Synthesis of Highly Functionalized Tetrahydropyridines
作者:Xue-Feng Zhu、Jie Lan、Ohyun Kwon
DOI:10.1021/ja0344009
日期:2003.4.1
3-butadienoate acts as a 1,4-dipole synthon and undergoes [4 + 2] annulation with N-tosylimines in the presence of an organic phosphine catalyst. The resulting adducts, ethyl 6-substituted-1-(4-tosyl)-1,2,5,6-tetrahydro-pyridine-3-carboxylates, are formed in excellent yields with complete regioselectivity. Mechanistic reasoning for this new annulation has led to an expansion of the reaction scope by employing
2-甲基-2,3-丁二烯酸乙酯作为 1,4-偶极合成子,在有机膦催化剂存在下与 N-甲苯磺酰亚胺发生 [4 + 2] 环化。得到的加合物 6-取代-1-(4-甲苯磺酰基)-1,2,5,6-四氢-吡啶-3-羧酸乙酯以极好的收率形成,具有完全的区域选择性。通过使用 2-(取代-甲基)-2,3-丁二烯酸乙酯生成 2,6-顺式-二取代-1-(4-甲苯磺酰基)-乙酯,这种新环化的机理推理扩大了反应范围具有高非对映选择性的 1,2,5,6-四氢吡啶-3-羧酸盐。