... Volume: Page: ... To access clip molecules derived from 9,9-dimethyl-2,4,6,8-tetraazabicyclo[3.3. 1]nonane-3,7-diones substituted at the 1 ... of the skeleton (17a,b and 20), we developed a different synthetic route (Scheme 3). Compounds 17a,b and 20 were treated ...