((3R,4S)-4-Methoxy-5-oxo-tetrahydro-furan-3-yl)-carbamic acid tert-butyl ester

(2S,3S)-2-Benzyloxy-3-tert-butoxycarbonylamino-succinic acid 1-methyl ester

((3R,4S)-4-Benzyloxy-5-oxo-tetrahydro-furan-3-yl)-carbamic acid tert-butyl ester

[(3R,4S)-4-(Naphthalen-1-ylmethoxy)-5-oxo-tetrahydro-furan-3-yl]-carbamic acid tert-butyl ester

[(3R,4S)-4-(Naphthalen-2-ylmethoxy)-5-oxo-tetrahydro-furan-3-yl]-carbamic acid tert-butyl ester