204274-33-9Relevant academic research and scientific papers
Efficient route to (S)-azetidine-2-carboxylic acid
Futamura, Yasuhiko,Kurokawa, Masayuki,Obata, Rika,Nishiyama, Shigeru,Sugai, Takeshi
, p. 1892 - 1897 (2008/02/03)
A new and efficient route to (S)-azetidine-2-carboxylic acid (>99.9% ee) in five steps and total yield of 48% via malonic ester intermediates was established. As the key step, efficient four-membered ring formation (99%) was achieved from dimethyl (S)-(1′-methyl)benzylaminomalonate by treating with 1,2-dibromoethane (1.5 eq) and cesium carbonate (2 eq) in DMF. Krapcho dealkoxycarbonylation of dimethyl (1′S)-1-(1′-methyl) benzylazetidine-2,2-dicarboxylate, the product of this cyclization procedure, proceeded with preferential formation (2.7:1, 78% total yield) of the desired (2S,1′S)-monoester, with the help of a chiral auxiliary which was introduced on the nitrogen atom. The undesired (2R,1′S)-isomer could be converted to that with proper stereochemistry, by a deprotonation and subsequent reprotonation step. Finally, lipase-catalyzed preferential hydrolysis of the (2S,1′S)-monoester and subsequent deprotection provided enantiomerically pure (S)-azetidine-2-carboxylic acid in a 91% yield from the mixture of (2S,1′S)- and (2R,1′S)-isomers.
Process for producing optically active azetidine-2-carboxylic acid derivative
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, (2008/06/13)
There is provided a process for improving optical purity of azetidine-2-carboxylic acid of the following formula which comprises: preparing a solution of azetidine-2-carboxylic acid; and cooling the said solution in the presence of a seed crystal of one optional optical isomer of the azetidine-2-carboxylic acid to selectively recrystallize the optical isomer of the azetidine-2-carboxylic acid having the same configuration with respect to the carbon atom of the 2-position of the azetidine ring as the seed crystal.
