(4R,5R,6S)-4-[2-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-6-[(R)-1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3-(diphenoxy-phosphoryloxy)-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid allyl ester

(3S,4R)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-4-((1R,3R)-3-methoxy-2-oxo-cyclohexyl)-azetidin-2-one

(1S,5R,8aS,8bR)-1-((R)-1-Hydroxy-ethyl)-5-methoxy-2-oxo-1,2,5,6,7,8,8a,8b-octahydro-azeto[2,1-a]isoindole-4-carboxylic acid allyl ester

(2S,2aS,2bR)-2-((R)-1-Hydroxy-ethyl)-1-oxo-1,2,2a,2b,5,6-hexahydro-4H-3-oxa-7a-aza-cyclobuta[a]indene-7-carboxylic acid allyl ester

(2S,2aS,2bS)-2-((R)-1-Hydroxy-ethyl)-1-oxo-1,2,2a,2b,5,6-hexahydro-4H-3-oxa-7a-aza-cyclobuta[a]indene-7-carboxylic acid allyl ester