(4SR)-acetoxy-(3S)-<(1R)-tert-butyldimethylsilyloxyethyl>azetidin-2-one 、
4,4-二甲基-3-乙酰胺恶唑烷-2-硫 在
N-乙基哌啶 、 tin(II) trifluoromethanesulfonate 作用下,
生成 (R)-3-[(S)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-4-[(S)-2-(4,4-dimethyl-2-thioxo-oxazolidin-3-yl)-1-methyl-2-oxo-ethyl]-azetidin-2-one 、 (R)-3-[(S)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-4-[(R)-2-(4,4-dimethyl-2-thioxo-oxazolidin-3-yl)-1-methyl-2-oxo-ethyl]-azetidin-2-one