Mild and Selective Synthesis of an Aryl Boronic Ester by Equilibration of Mixtures of Boronic and Borinic Acid Derivatives
作者:Vanessa F. Hawkins、Mark C. Wilkinson、Matthew Whiting
DOI:10.1021/op800169s
日期:2008.11.21
of aryl Grignard reagents with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (isopropyl pinacol borate) under noncryogenic conditions can lead to mixtures of the corresponding boronic ester along with, generally undesired, borinic acid derivatives. We have found that in certain cases gentle heating of the crude reaction mixtures leads to complete equilibration to give the borinic esters as the
在非低温条件下用2-异丙氧基-4,4,5,5-四甲基-1,3,2-二氧杂硼烷(异丙基频哪醇硼酸酯)淬灭芳基格氏试剂会导致相应的硼酸酯与通常不希望的硼酸酯混合物,硼酸衍生物。我们发现,在某些情况下,粗制反应混合物的温和加热导致完全平衡,从而得到硼酸酯作为唯一产物,然后可以高收率分离。这种新的平衡可以减少使用低温条件或大量过量的试剂在硼酸酯合成过程中获得选择性的需要。