Efficient Synthesis of Chiral 1,1′-Binaphthalenes by the Asymmetric Suzuki–Miyaura Reaction: Dramatic Synthetic Improvement by Simple Purification of Naphthylboronic Acids
作者:Miroslav Genov、Antonio Almorín、Pablo Espinet
DOI:10.1002/chem.200600616
日期:2006.12.13
Naphthylboronic acids prepared as reported in the literature are contaminated with HCl. A very simple purification prior to their use in Suzuki-Miyaura couplings has been found to be crucial, rendering efficient some reactions that had been reported in the literature either to fail or to give extremely poor yields. With this improvement, parent boronic acids can be used instead of esters at moderate
如文献报道制备的萘基硼酸被HCl污染。已经发现在将其用于铃木-宫浦联轴器之前非常简单的纯化是至关重要的,这使得文献中报道的某些反应有效或失败或收率极低。通过这种改进,在中等温度下可以使用母体硼酸代替酯,并且可以使用溴代衍生物代替碘代衍生物。通过使用硼酸,溴萘和二茂铁基膦配体,可以方便地获得手性空间位阻的双萘衍生物。得到的产物具有良好的收率(95-55%)和良好的对映选择性(90-50%)。较大的配体在受阻配偶的偶联中效率较低。