2-Azaspiro[3.3]heptane-2-carboxylic acid tert-butyl ester
1,6-Diazaspiro[3.4]octane-6-carboxylic acid tert-butyl ester
2,5-Diazaspiro[3.4]octane-5-carboxylic acid tert-butyl ester
1,7-Diazaspiro[4.4]nonane-7-carboxylic acid tert-butyl ester
1,7-Diazaspiro[4.4]nonane-1-carboxylic acid tert-butyl ester
3-Oxo-1-Oxa-7-azaspiro[4.4]nonane-7-carboxylic acid tert-butyl ester
1,6-Diazaspiro[3.5]nonane-6-carboxylic acid tert-butyl ester
1,7-Diazaspiro[3.5]nonane-7-carboxylic acid tert-butyl ester
4-Oxohexahydrocyclopenta[c]pyrrole-2-carboxylic acid tert-butyl ester
1,7-Diazaspiro[4.5]decane-7-carboxylic acid tert-butyl ester