((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

carbonic acid allyl ester (2S,3R)-2-(9H-fluoren-9-ylmethoxycarbonylamino)-3-hydroxy-pent-4-enyl ester

((R)-1-(S)-2,5-Dihydro-furan-2-yl-2-hydroxy-ethyl)-carbamic acid tert-butyl ester