The absolute configuration of trans-1,2-dimethylcyclopropane

By application of the newly discovered fact that 1° alkyl chlorides with γ-hydrogen form cyclopropanes on treatment with sodium metal, (?)-trans-1,2-dimethylcyclopropane has been prepared from (+)-1-chloro-2-methylbutane. Rigorous assignment of configuration to the isomeric cis- and trans-dimethylcyclopropanes is thereby achieved. The absolute configuration, (1R : 2R) trans-1,2-dimethylcyclopropane, can be assigned to the (?) enantiomer by several lines of argument and agrees with that calculated by Fitts.