Energy barrier, and conformation

Potential-energy barriers and conformations for tertiary substituents bonded to olefins have been reported in only a few cases. An interesting example is tetrakis(l-methylcyclopropyl)ethylene, which adopts a conformation of Z>2 symmetry with alternating up and down cyclopropyl groups and a barrier (AG = 14.8 kcal mol" ) slightly lower than for tetraisopropylethylene (Loerzer et al. 1983). 

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