benzyl 5,5-dimethoxy-8-oxo-3-azabicyclo<4.2.0>octane-3-carboxylate

1-benzyloxycarbonyl-N,N-dimethyl-1,6-dihydro-3(2H)-oxopyridine-4-acetamide

rel-benzyl (4R,5S)-4-(2-(dimethylamino)-2-oxoethyl)-5-hydroxy-3,3-dimethoxypiperidine-1-carboxylate

benzyl 7-hydroxy-6-oxo-2-azabicyclo<2.2.2>octane-2-carboxylate