The rearrangement of cyclopropyl chlorides to allyl chlorides : Stereospecificity in the recapture of the chloride ion

The cyclopropyl chlorides (1 and 2) rearrange on heating to give stereospecifically the allyl chlorides (3 and 4, respectively). In the presence of nucleophiles such as methoxide ion, the corresponding allyl ethers (5 and 6, respectively) are formed. Analysis of the stereochemistry of these products indicates that they are formed from the corresponding allyl chlorides (3 and 4), which are evidently the first-formed products of the reaction even in the presence of strong nucleophiles. The reaction of the allyl chlorides (3 and 4) with sodium phenylthioxide in aprotic non-polar solvents goes predominantly with retention of configuration, but in methanol is normal in giving predominantly inversion of configuration.