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

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

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

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

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

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

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

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

4-(2-chloro-5-nitrobenzoyl)-8-methyl-1-oxa-4,8-diazaspiro[4.5]decane-3-carboxylic acid

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

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