Synthesis of Axially Chiral Biaryls by Atropo-Diastereoselective Cleavage of Configurationally Unstable Biaryl Lactones with Menthol-DerivedO-Nucleophiles
作者:Gerhard Bringmann、Matthias Breuning、Rainer Walter、Andreas Wuzik、Karl Peters、Eva-Maria Peters
DOI:10.1002/(sici)1099-0690(199911)1999:11<3047::aid-ejoc3047>3.0.co;2-o
日期:1999.11
Configurationally unstable lactone-bridged biaryls 4 are cleaved atropo-diastereoselectively using chiral menthol-derived alkali metal alkoxides, to give axially chiral biaryl esters of type 5 in high yields and excellent diastereomeric ratios of up to > 99:1. The method permits the optional preparation of each of the two atropisomers from the same lactone precursor (“atropo-divergence”), simply according
使用手性薄荷醇衍生的碱金属醇盐选择性地将构型不稳定的内酯桥连的联芳基4裂解为对映体-非对映异构体,从而以高收率和高达> 99:1的极佳非对映异构体比例得到轴向类型5的轴向手性联芳基酯。该方法只需根据适当的薄荷酸酯或其对映异构体(如O-亲核试剂)的选择,或通过使用薄荷酸酯,就可以从同一内酯前体中任选地制备两种阻转异构体中的每一种(“阻转性”)。溶液或悬浮液。可能形成的不希望的次要阻转异构体5(如果有的话)可以通过环化回内酯4进行再循环(“轴向手性经济”)。。为了制备大量对映体纯的联芳醇9,开发了一种有效的反应序列:4的醇解原位还原结晶。这些醇解反应对于不对称联芳基合成的合成值通过将5转化为一系列具有对轴正交的各种官能团的6型对映纯联芳基进行说明。