solution. They were first applied to catalyze aldol reactions, and were found to be effective catalysts for the transformations. The tetrapeptide Val-d-Pro-Gly-Leu-OH (1g) was the optimal organocatalyst. It was shown that the intensive β-turn conformation, indicated by CD and NOESY spectra, contributed to the (R)-aldol and high enantioselectivity of the reaction of acetone in MeOH, whereas the sharply varied
设计并合成了四肽,该四肽包含一个终止的
伯胺和构象受限的d -Pro-Gly或d -Pro-Aib(2-
氨基
异丁酸)链段作为强β-转核元素,并通过N-模块二肽与溶液中的C模块二肽。它们首先被用于催化羟醛反应,并被发现是有效的转化
催化剂。四肽Val- d -Pro-Gly-Leu-OH(1g)是最佳的有机
催化剂。结果表明,在密集的β转角构象,通过CD和NOESY光谱表明,促成了(ř)-
丙酮中的
丙酮反应具有较高的对映选择性,而急剧变化的构象应有助于
1,2-二氯乙烷(DCE)中反应的低对映选择性和(S)产物。
羟基丙酮反应中的不对称诱导不受溶剂的影响,在MeCN中添加1克
添加剂(S)-BINOL可达到主要的反产物。