作者:Carlo Scolastico、Esterino Conca、Laura Prati、Giuseppe Guanti、Luca Banfi、Adriano Berti、Paolo Farina、Umberto Valcavi
DOI:10.1055/s-1985-31363
日期:——
(d,l)-threo and allo-2-amino-4,4,4-trifluoro-3-hydroxybutanoic acids are synthesised from ethyl trifluoroacetoacetate via reduction and saponification of the 4,4,4-trifluoro-3-hydroxy-2-methoxyiminobutanoate. threo-Isomers are stereospecifically obtained by epimerisation of allo-isomers via the corresponding oxazolidinones. An acylation and stereoselective reduction sequence performed on ethyl N,N-dibenzylaminoacetate also leads to threo-isomers (1A) in good yields. An enantioselective synthesis of (L)-4-fluorothreonine by regiospecific opening of (2S), (3R)-3-benzyloxyoxiranecarboxylic acid is reported.
(d,l)-threo和allo-2-氨基-4,4,4-三氟-3-羟基丁酸是通过乙基三氟乙酰乙酸酯的还原和水解4,4,4-三氟-3-羟基-2-甲氧基亚氨基丁酸酯来合成的。通过相应的唑烷酮的差向异构化可以立体特异性地获得threo异构体。在乙基N,N-二苄基氨基乙酸酯上进行的酰化和立体选择性还原序列也能以良好的产率得到threo异构体(1A)。报道了一种通过(2S),(3R)-3-苄氧基环氧乙烷羧酸的区域特异性开环来选择性合成(L)-4-氟苏氨酸的方法。