((S)-1,4-Dibenzyl-2-oxo-pent-4-enyl)-carbamic acid tert-butyl ester

[(S)-1-((S)-4-Benzyl-5-oxo-2,5-dihydro-furan-2-yl)-2-phenyl-ethyl]-carbamic acid tert-butyl ester

(4S,5R)-4-Benzyl-2,2-dimethyl-oxazolidine-3,5-dicarboxylic acid 3-tert-butyl ester 5-methyl ester

(Z)-(S)-2-Benzyl-5-tert-butoxycarbonylamino-4-oxo-6-phenyl-hex-2-enoic acid methyl ester

(3R,5S)-3-benzyl-5-{(1S)-1-[(tert-butoxycarbonyl)amino]-2-phenylethyl}dihydrofuran-2-(3H)-one