Question

Why cant 1,2,3- Trimethyl cyclopropane have a cis or a trans formation?

Answer 1

The structure of 1,2,3- Trimethyl cyclopropane is as follows:

Generally. cis or trans formation are used only when there is double bond present in the molecule.Since here we donot have any doubles ,there is no need to use cis/trans notation.

In 1,2-dimethyl cyclobutane , there is possibility than 1 methyl group out of plane and other in same plane. so there we will represent using wedge and dash structures. If 2 groups are present inside ring we use cis and outside ring we call it trans. But here we have 3 substituted methyl groups We cannot assign both cis and trans for same stable molecule (if 2 orient in 1 way and other in other way).so , there will be no cis and trans for this molecule