Efficient ball-mill procedure in the ‘green’ asymmetric aldol reaction organocatalyzed by (S)-proline-containing dipeptides in the presence of water
作者:José G. Hernández、Eusebio Juaristi
DOI:10.1016/j.tet.2011.06.042
日期:2011.9
activity of (S)-proline-based dipeptides 1a–c has been evaluated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solvent-free conditions in a ball mill. In particular, the methyl ester of (S)-proline-(S)-tryptophan, (S,S)-1c, proved to be an efficient organocatalyst, and the aldol reaction proceeded with good chemical yields and excellent diastereo- and
(S)-脯氨酸基二肽1a – c的有机催化活性已在无磨条件下在球磨机中通过代表性的酮与各种芳族醛之间的不对称羟醛反应进行了评估。特别地,(的甲酯小号)-proline-(小号) -色氨酸,(小号,小号) - 1C,被证明是一种有效的有机催化剂,并具有良好的化学产率和优异的diastereo-和对映选择性(进行醛醇缩合反应在水和5摩尔%苯甲酸作为添加剂的情况下,抗/合成比最高至98:2,抗反式和合成基极高达98%ee)。