8-ethyl-4-(3-nitrobenzoyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-ethyl-4-(2-phenylbutanoyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-ethyl-4-(3-methoxybenzoyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-ethyl-4-(3-methylbenzoyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

4-(4-nitrobenzoyl)-8-propyl-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-propyl-4-(thiophene-2-carbonyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-propyl-4-(pyridine-3-carbonyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

4-(3,4-difluorobenzoyl)-8-propyl-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-propyl-4-(2,4,6-trimethylbenzoyl)-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

8-tert-butyl-4-(3-fluorobenzoyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

8-benzyl-4-propanoyl-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid