A Direct, Concise, and Enantioselective Synthesis of 2-Substituted 4,4,4-Trifluorobutane-1,3-diols Based on the Organocatalytic In Situ Generation of Unstable Trifluoroacetaldehyde
作者:Kazumasa Funabiki、Yudai Furuno、Yosuke Yano、Yuta Sakaida、Yasuhiro Kubota、Masaki Matsui
DOI:10.1002/asia.201500607
日期:2015.12
A direct, concise, and enantioselective synthesis of 2‐substituted 4,4,4‐trifluorobutane‐1,3‐diols based on the organocatalytic asymmetric direct aldol reaction of an ethyl hemiacetal of trifluoroacetaldehyde with various aldehydes was examined. A catalytic amount (30 mol %) of commercially available and inexpensive l‐prolinamide is quite effective as an organocatalyst for the catalytic in situ generation
基于三氟乙醛的乙基半缩醛与各种醛类的有机催化不对称直接羟醛直接反应,研究了2-取代的4,4,4-三氟丁烷-1,3-二醇的直接,简明和对映选择性合成。催化量(30 mol%)的市售廉价廉的l-脯氨酰胺非常有效地用作有机催化剂,用于从其半缩醛催化原位生成气态和不稳定的三氟乙醛,以及随后与各种醛在二氯甲烷中的连续不对称直接羟醛反应。 0°C,然后用硼氢化钠还原,可得到2-取代的4,4,4-三氟丁烷-1,3-二醇,产率中等至良好(31-84%),非对映选择性低,对映选择性良好(64- 97% ee)。