Process for the synthesis of chirally pure beta-amino-alcohols

摘要

A process is provided for preparing chirally pure S-enantiomers of alpha-amino acids comprising the steps of: a) preparing an organometallic reagent from an alkyl halide of the formula (R)2CH(CH2)nCH2X; b) adding the organometallic reagent to carbon dioxide to afford a carboxylic acid; c) activating the carboxylic acid with an acid chloride, phosphorus trichloride, acid anhydride, or thionyl chloride in the presence of a tertiary amine base; d) reacting the product of step c) with an alkali metal salt of S-4-benzyl-2-oxazolidinone; e) treating the product of step d) with a strong non-nucleophilic base to form an enolate anion; f) trapping the enolate anion with 2,4,6-triisopropylbenzenesulfonyl azide to afford an oxazolidinone azide; g) hydrolyzing the oxazolidinone azide with an aqueous base to afford an alpha-azido acid; h) reducing the alpha-azido acid to the alpha-amino acid; and i) recrystallizing the alpha-amino acid to the chirally pure alpha-amino acid. A process is also provided for preparing chirally pure S-enantiomers of beta-amino alcohols further comprising the steps of reducing the crude alpha-amino acid to the beta-amino alcohol and recrystallizing the beta-amino alcohol to the chirally pure beta-amino alcohol. A process is further provided for preparing chirally pure S enantiomers of N-sulfonyl beta-amino alcohols further comprising the steps of sulfonylating the beta-amino alcohol with 5-chloro-thiophene-2-sulfonyl halide; and recrystallizing to afford the chirally pure N-sulfonyl beta-amino alcohols.