tert-butyl (10R,12R)-10-allyl-12-methyl-9-oxo-3,4,6,7,8,9,10,11,12,13-decahydrobenzo[j][1]oxa[5]azacycloundecine-5(2H)-carboxylate

tert-butyl (1R,3R,6S)-1-allyl-3-methyl-5,14-dioxo-10-azaspiro[5.8]tetradecane-10-carboxylate

tert-butyl (1R,3R,5S,6R)-1-allyl-5-hydroxy-3-methyl-14-oxo-10-azaspiro[5.8]tetradecane-10-carboxylate

tert-butyl (1R,3R,5R,6R)-1-allyl-5-hydroxy-3-methyl-14-oxo-10-azaspiro[5.8]tetradecane-10-carboxylate

tert-butyl (1S,3R,5S,6R)-1-hydroxy-3-methyl-14-oxo-5-(2-oxoethyl)-10-azaspiro[5.8]tetradecane-10-carboxylate