Synthesis of optically active β-lactams by the reaction of 2-acyl-3-phenyl-<i>l</i>-menthopyrazoles with CN compounds
作者:Choji Kashima、Kiyoshi Fukusaka、Katsumi Takahashi
DOI:10.1002/jhet.5570340529
日期:1997.9
The reaction of 1-acyl-3,5-dimethylpyrazoles 1 with CN compounds was kinetically controlled with syn stereoselectivity through a lithium enolate intermediate using lithium diisopropylamide. In contrast, the anti stereoselective reaction of 1 was caused by the action of diisopropylethylamine in the presence of magnesium bromide under the thermodynamic control. Reaction of 2-acyl-3-phenyl-l-menthopyrazoles
1-酰基-3,5-二甲基吡唑1与C N化合物的反应是通过使用二异丙基氨基化锂的烯醇锂中间体以顺式立体选择性动力学控制的。相反,在热力学控制下,在溴化镁存在下,二异丙基乙胺的作用引起1的抗立体选择性反应。观察到2-酰基-3-苯基-1-薄荷脑吡唑12与C N化合物以主要的2'S构型以较高的化学和光学产率反应。在2-丙酰基-3-苯基-1-薄荷脑吡唑(12a)与N-亚苄基-4-甲苯磺酰胺(2)。将N-酰基-吡唑和C N化合物的产物直接或以短转化步骤进一步环化成β-内酰胺。