Synthesis of O-benzyl azetedinone derivatives of (R) & (S)-2-aminobutanols

Some new chiral azetedinone derivatives from O-benzyl protected (R) & (S)-2-amino-1-butanols have been reported. (R) & (S)-2-Amino-1-butanols were first converted into their O-benzyl derivatives through a known methodology, which were then converted into the azetedinone derivatives via the formation of Schiff's bases and the usual keteneimine cycloaddition reaction. The reaction was found to take place with a great deal of stereoselectivity which may be attributed to blocking of one of the faces of the imine by the bulky benzyl group and the ethyl group.