6-Fluoro-(7), 6-fluoro-6-methyl-(8), and 6, 6-difluoro-5, 7-dioxo-1, 4, 8, 1l- tetraazacyclotetradecane (9) were synthesized by condensation of 5 with each corresponding fluorine-substituted malonic ester8 (2: 3, and 4) in refluxing ethanol. The cyclization becomes faster as more F is substituted, completing within 30 min with difluorinated 4 as compared to 3 days with nonfluorinated 1,'O with yields of 39%(for 7), 54 ...
