2,4-Dinitrophenol as an Effective Cocatalyst: Greatly Improving the Activities and Enantioselectivities of Primary Amine Organocatalysts for Asymmetric Aldol Reactions
作者:Chao-Shan Da、Li-Ping Che、Qi-Peng Guo、Feng-Chun Wu、Xiao Ma、Ya-Ning Jia
DOI:10.1021/jo802758b
日期:2009.3.20
Seven primary amine organocatalysts 1a−g were readily prepared from natural primary amino acids via two steps and then were used to catalyze the direct asymmetric aldol reaction, but they showed very poor enantioselectivities and activities. As an effective cocatalyst, 2,4-dinitrophenol (DNP) dramatically elevated the activities and enantioselectivities of these very inefficient primary amine organocatalysts
可以通过两步从天然伯氨基酸容易地制备出7种伯胺有机催化剂1a - g,然后将其用于催化直接不对称羟醛反应,但它们的对映选择性和活性非常差。作为一种有效的助催化剂,2,4-二硝基苯酚(DNP)大大提高了这些非常低效的伯胺有机催化剂的活性和对映选择性。与从头开发催化剂相比,通过选择和使用最佳助催化剂对非常低效的有机催化剂进行这种补救的过程特别具有成本效益且对环境有利。由1f组成的最高效的有机催化系统DNP表现出高的对映选择性和良好的非对映选择性,具有广谱的七种酮。线性酮和环戊酮主要合成产物,而环己酮主要产生反产物。