(2aS,2bS,5aS,6R)-2-Eth-(Z)-ylidene-2b-methyl-1,4-dioxo-octahydro-3-oxa-6a-aza-cyclobuta[a]pentalene-6-carboxylic acid benzyl ester

(2S,2aS,2bS,5aS,6R)-2-((R)-1-Methanesulfonyloxy-ethyl)-2b-methyl-1,4-dioxo-octahydro-3-oxa-6a-aza-cyclobuta[a]pentalene-6-carboxylic acid benzyl ester

4-乙酰氧基氮杂环丁酮

3S-<1R-(tert-butyldimethylsilanyloxy)ethyl>-4S-(2S-methyl-5-oxo-2,5-dihydrofuran-2-yl)azetidin-2-one

(2S,2aS,2bS,5aS,6R)-2-((R)-1-Hydroxy-ethyl)-2b-methyl-1,4-dioxo-octahydro-3-oxa-6a-aza-cyclobuta[a]pentalene-6-carboxylic acid benzyl ester

<3S-<1R-(tert-butyldimethylsilanyloxy)ethyl>-2S-(2-methyl-5-oxo-2,5-dihydrofuran-2-yl)-4S-oxo-azetidin-1-yl>acetic acid benzyl ester

(2S,2aS,2bS,5aS,6R)-2-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-2b-methyl-1,4-dioxo-octahydro-3-oxa-6a-aza-cyclobuta[a]pentalene-6-carboxylic acid benzyl ester