Cyclic Alkene Compounds cyclohexene cyclooctene trans-cyclodecene cis-cyclodecene Copyright 2010 Pearson Prentice Hall,Inc. -Trans cycloalkenes are not stable unless the ring has at least eight carbons. -Cycloalkenes are assumed to be cis unless otherwise specifically named frans. Cyclic Alkene Compounds Trans cycloalkenes are not stable unless the ring has at least eight carbons. Cycloalkenes are assumed to be cis unless otherwise specifically named trans