一种便捷的膦催化[4 + 2]环化反应：高官能团化四氢吡啶的合成。
An expedient phosphine-catalyzed [4 + 2] annulation: synthesis of highly functionalized tetrahydropyridines.
作者信息
Zhu Xue-Feng, Lan Jie, Kwon Ohyun
机构信息
Department of Chemistry, University of California, Los Angeles, California 90095-1569, USA.
出版信息
J Am Chem Soc. 2003 Apr 23;125(16):4716-7. doi: 10.1021/ja0344009.
Ethyl 2-methyl-2,3-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 ethyl 2-(substituted-methyl)-2,3-butadienoates to give ethyl 2,6-cis-disubstituted-1-(4-tosyl)-1,2,5,6-tetrahydro-pyridine-3-carboxylates with high diastereoselectivities.
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]环化反应。生成的加合物，即6-取代-1-(4-甲苯磺酰基)-1,2,5,6-四氢吡啶-3-羧酸乙酯，以优异的产率和完全的区域选择性形成。对这种新环化反应的机理推导使得通过使用2-(取代甲基)-2,3-丁二烯酸乙酯来扩大反应范围，从而以高非对映选择性得到2,6-顺式二取代-1-(4-甲苯磺酰基)-1,2,5,6-四氢吡啶-3-羧酸乙酯。
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