(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.
Diastereo and Enantioselective Synthesis of Fluorinated Threonines
GUANTI, GIUSEPPE;BANFI, LUCA;
1985-01-01
Abstract
(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.
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