(3R,4R)-4-Ethynyl-3-((S)-1-hydroxy-ethyl)-1-(4-methoxy-benzyl)-azetidin-2-one
(3R,4R)-4-Ethynyl-3-((R)-1-hydroxy-ethyl)-1-(4-methoxy-benzyl)-azetidin-2-one
(3R,4S)-4-Ethynyl-3-((R)-1-hydroxy-ethyl)-1-(4-methoxy-benzyl)-azetidin-2-one
(3S,4S)-4-Ethynyl-3-<(1R)-hydroxyethyl>-N-p-methoxybenzyl-2-azetidinone
(3S,4R)-4-Ethynyl-3-((S)-1-hydroxy-ethyl)-1-(4-methoxy-benzyl)-azetidin-2-one