4-[3-(trifluoromethyl)benzoyl]-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-(4-methyl-3-nitrobenzoyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-(2,4-difluorobenzoyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-(2-chloro-5-nitrobenzoyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-benzoyl-8-methyl-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-(3,5-dinitrobenzoyl)-8-methyl-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-[2-(4-methoxyphenyl)acetyl]-8-methyl-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

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

8-methyl-4-[4-(trifluoromethyl)benzoyl]-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

8-methyl-4-(pyridine-3-carbonyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

4-[2-(4-chlorophenyl)acetyl]-8-methyl-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid