Cyclododecanedione and 1, 8-cyclotetradecanedione were prepared from bis-Grig- nard reagent and dinitriles. This is a convenient synthetic method for large-ring cycloalkanediones. Cyclododecanedione and 1, 8-cyclotetradecanedione were prepared from bis-Grignard reagents and dinitriles. This is a convenient synthetic method for large-ring cycloalkanes.