Optical Resolution of 5‐Oxo‐1‐Phenyl‐Pyrazolidine‐3‐Carboxylic Acid as a New Organocatalyst for Organic Reactions |
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| Authors: | Zheng‐Hao Tzeng Shuen‐Wen Yang Pang‐Min Liu Kwun‐Min Chen |
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| Institution: | Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan 116, R.O.C. |
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| Abstract: | Optical resolution of racemic 5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid 2 with L‐amino acid methyl ester via the diastereomers formation was investigated. Treatment of racemic 5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid 2 with L‐valine methyl ester gave diastereomers with a total yield of 86%. The diastereomeric dipeptides can be easily separated by flash column chromatography. Acidic cleavage of the derived diastereomers gave both the optically pure (+)‐(R)‐ and (‐)‐(S)‐5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid ((+)‐(R)‐ 2 and (‐)‐(S)‐ 2 ) with a total yield of 94% and 95%, respectively. |
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| Keywords: | Optical resolution Organocatalyst 5‐Oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid L‐Amino acid |
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