benzyl ((3R,4R)-1-(benzyloxy)-4-methyl-2-oxopyrrolidin-3-yl)carbamate

(2R,3S)-t-butyl 2-N-(benzyloxycarbonyl)-4-bromo-3-methylbutanoate

ethyl 3-methyl-4-oxobutanoate

4,4-Dimethoxy-3-methyl-butyric acid ethyl ester