作者:Marcel K. Eberle、Reinhart Keese、Helen Stoeckli-Evans
DOI:10.1002/hlca.19980810117
日期:1998.1.12
(−)-(R)-4,4,4,4′,4′,4′-Hexafluorovaline hydrochloride ((R)-5) of 98% ee is prepared from β,β-bis(trifluoromethyl)acrylic acid (= benzyl 4,4,4-trifluoro-3-(trifluoromethyl)but-2-enoate; 1) in 4 steps with an overall yield of 9.6%. Key step is the separation of the TsOH salts of the diastereoisomers obtained by anti-Michael addition of (+)-(R)-1-phenylethylamine (2) to 1 ( (R,R)-3). In contrast to the
(-)-(R)-4,4,4,4',4',4'- 98%ee的六氟缬氨酸盐酸盐((R)-5)由β,β-双(三氟甲基)丙烯酸( =4个步骤中的4,4,4-三氟-3-(三氟甲基)丁-2-烯酸苄酯;1),总产率为9.6%。关键步骤是分离通过将(+)-(R)-1-苯基乙胺(2)反迈克尔加成1((R,R)-3)而获得的非对映异构体的TsOH盐。与已发表的(S)手性相反,(R,S)-6的X射线结构分析表明,(R)-手性必须分配给左旋(-)-4,4,4,4',4',4'-六氟缬氨酸盐酸盐。