(5R)-benzyl 4-(3,3-dimethyl-1-oxo-2-oxa-7-azaspiro[4.5]dec-7-yl)piperidine-1-carboxylate
(5S)-benzyl 4-(3,3-dimethyl-1-oxo-2-oxa-7-azaspiro[4.5]dec-7-yl)piperidine-1-carboxylate
benzyl 4-(3,3-dimethyl-1-oxo-2-oxa-7-azaspiro[4.5]dec-7-yl)piperidine-1-carboxylate
tert-butyl 3,3-dimethyl-1-oxo-2-oxa-7-azaspiro[4.5]decane-7-carboxylate
tert-butyl 3-methyl-1-oxo-2-oxa-7-azaspiro[4.5]decane-7-carboxylate