<3S-<3α(S*),4α>>-1-(2,4-dimethoxybenzyl)-3-(1-acetoxyethyl)-4-ethoxycarbonyl-2-azetidinone-4-carboxylic acid

<3S-<3α(S*),4β>>ethyl 1-(2,4-dimethoxybenzyl)-3-(1-acetoxyethyl)-2-azetidinone-4-carboxylate

<3S-<3α(S*),4β>>-benzyl<3-(1-t-butyldimethylsilyloxyethyl)-2-azetidinone-4-yl>acetate

<3S-<3α(S*),4β>>-1-(2,4-dimethoxybenzyl)-3-(1-t-butyldimethylsilyloxyethyl)-4-diazoacetyl-2-azetidinone

<3S-<3α(S*),4α>>ethyl 1-(2,4-dimethoxybenzyl)-3-(1-acetoxyethyl)-2-azetidinone-4-carboxylate

[(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-1-(2,4-dimethoxy-benzyl)-4-oxo-azetidin-2-yl]-acetic acid methyl ester

<1R-(1α,4α,5α)>-7-(2,4-dimethoxybenzyl)-2,6-dioxo-4-methyl-3-oxa-7-azabicyclo<3.2.0>heptane