A STEREOCHEMICAL STUDY OF THE ISOMERIZATION OF CYCLOPROPYL ETHERS TO ALLYL ETHERS CATALYZED WITH ZINC IODIDE

Optically active 1-alkoxybicyclo[4.1.0]heptane was converted using zin c iodide as a catalyst to 2-alkoxymethylidenecyelohexane without loss of optical purity. The mechanism of the isomerization was studied usin g a stereochemical analysis of the product and deuterium labeling expe riments. The results indicated that the isomerization takes place thro ugh a stepwise mechanism that involves an attack of zinc iodide on the cyclopropane ring: to cause ring opening, followed by an intramolecul ar 1,2-hydride shift with liberation of the zinc iodide.