Concise and practical syntheses of 8-oxa-3-aza-bicyclo[3.2.1]octane and 9-oxa-3-aza-bicyclo[3.3.1]nonane are described starting from furan-2,5-dicarboxylic acid and 4H-pyran-2,6-dicarboxylic acid, respectively, and using a solvent-free step for a key cyclisation.