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

8-tert-butyl-4-(thiophene-2-carbonyl)-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

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

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

8-tert-butyl-4-[(2Z)-3-phenylprop-2-enoyl]-1-oxa-4-azaspiro[4.5]decane-3-carboxylic acid

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

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

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

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

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

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