4-(furan-2-carbonyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

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

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

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

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

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

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

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

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

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

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

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

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