Structures with One Stereogenic Center

Now consider a compound in which the two paths around the ring are not equivalent. In 3-meth-ylcyclohexene, a methyl group and a hydrogen atom are bonded to C-3. C-2 and C-4 are not equivalent by rule 3. As a result, C-3 of 3-methylcyclohexene is a stereogenic center. The structure of (i )-3-methylcyclohexene is shown below. We see that it does not have a plane of symmetry. 

As in acyclic compounds, differences in the groups can be at some distance from the stereogenic center. The difference in 4-methylcyclohexene is two carbon atoms away from the stereogenic center. 

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