3-Methylazetidin-2-one and its precursors: Optical resolution and absolute configurations

Article abstract of DOI:10.1016/0957-4166(96)00065-1

Enantiomers of 3-methylazetidin-2-one - (3R)-(+)- and (3S)-(-)-1 and 3-amino-2-methylpropionic acid - (2R)-(-)- and (2S)-(+)-2 were obtained from corresponding diastereomers of methyl (αS)-N-α-methylbenzyl-3-amino-2-methylpropionate 3A,B which had been separated by recrystallization of their salts 4A,B with p-toluenesulfonic acid. The absolute configurations of azetidinones (+)- and (-)-1 and their diastereomeric precursors, i.e. amino esters 3A,B, (αS)-N-α-methylbenzyl-3-amino-2-methylpropionic acids 5A,B, and (αS)-N-α-methylbenzyl-3-methylazetidin-2-ones 6A,B were established by conversion of (+)-1 to amino acid (2R)-(-)-2 and of amino acid (2S)-(+)-2 to (-)-1.