1. R. W. Hoffmann and B. Kemper, Tetrahedron Letters, in press.
2. This compound has been independently studied by P. G. M. Wuts, personal communicate, October 1980.
3. Thermodynamics of vinyl ethers—XVIII
4. Preparation of Ketals from 2,2-Dimethoxypropane1
5. D. A. Evans, J. V. Nelson and T. R. Taber, Topics of Stereochemistry, in press.