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

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

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

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

4-{[1,1'-biphenyl]-4-carbonyl}-8-methyl-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

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

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

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

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

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

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