Despite attempts, the alkene 2,2,5,5-tetramethyl-3,4-(dimethylethyl)-3-hexene has never been synthesized. Because?.
SOLUTION:

Very unstable compound due to the repulsion between tert -butyl groups.
Despite attempts, the alkene 2,2,5,5-tetramethyl-3,4-(dimethylethyl)-3-hexene has never been synthesized. Because?.