- Optical resolution by preferential crystallization of (RS)-2-benzoylamino-2-benzyl-3-hydroxypropanoic acid and its use in synthesizing optically active 2-amino-2-methyl-3-phenylpropanoic acid.
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To synthesize optically active 2-amino-2-methyl-3-phenylpropanoic acid (1), (RS)-2-benzoylamino-2-benzyl-3-hydroxypropanoic acid [(RS)-2] was first optically resolved using cinchonidine as a resolving agent to yield optically pure (S)- and (R)-2 in yields of about 70%, based on half of the starting amount of (RS)-2. Next, the racemic structure of (RS)-2 was examined based on melting point, solubility, IR spectrum, and binary and ternary phase diagrams, with the aim of optical resolution by preferential crystallization of (RS)-2. Results indicated that the (RS)-2 exists as a conglomerate at room temperature, although it forms a racemic compound at the melting point. The optical resolution by preferential crystallization yielded (S)- and (R)-2 with optical purities of about 90%, which were fully purified by recrystallization. After O-tosylation of (S)- and (R)-2, reduction by zinc powder and sodium iodide gave (R)- and (S)-1, respectively.
- Shiraiwa, Tadashi,Suzuki, Masahiro,Sakai, Yoshio,Nagasawa, Hisashi,Takatani, Kazuhiro,Noshi, Daisuke,Yamanashi, Kenji
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p. 1362 - 1366
(2007/10/03)
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- α-Hydroxymethylphenylglycine and α-hydroxymethylphenylalanine: Synthesis, resolution, and absolute configuration
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Racemic α-hydroxymethylphenylglycine and α-hydroxymethylphenylalanine have been synthesized by selective hydroxymethylation of oxazolones derived from phenylglycine and phenylalanine, and resolved into enantiomers by fractional crystallization of their di
- Olma
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p. 1442 - 1447
(2007/10/03)
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