A. Jesus Velho, J. Martins
2020
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Journal
Journal of the Brazilian Chemical Society
Abstract
Chiral amino alcohols are very versatile compounds used in organic chemistry as chiral auxiliaries, chiral ligands and synthetic intermediates. They also present high biological activity, and take part in the structure of valuable drugs. Syn and anti 1,2-diphenyl2-aminoethanol, 1 and 2 (Figure 1), have been used widely as part of designed ligands for asymmetric transformations including α-arylation of α-aminoacids, synthesis of enantiomerically enriched 1,2-diaryl carbonyl compounds, asymmetric Baeyer-Villiger oxidation, asymmetric epoxidation of alkylidenemalononitriles, among others. (1S,2S)-Pseudoephenamine 3 and (1S,2R)-ephenamine 4 (Figure 1) are known chiral auxiliaries used in diastereoselective alkylations which provide alcohols, ketones and carboxylic acids with high enantiomeric purity. Several synthetic methods have been reported for the synthesis of (1S,2R)-ephenamine 4, as well as the respective (1S,2R)-1,2-aminoalcohol 2, however, to the best of our knowledge, none of these methods starts from readily available chiral amino acid. Zhou et al. has described the synthesis of enantiopure syn N-Boc-protected-1,2-amino alcohols in good yields from readily available L-amino acids in four reaction steps (Scheme 1). Ghorai et al. has described the synthesis of anti N-Boc-protected-1,2-amino alcohols starting from N-Boc-(S)-phenylglycine on a similar approach, nevertheless none chiral ephenamine 4 precursor had been synthesized (Scheme 2).