1. A. S. Gybin, V. S. Bogdanov, V. A. Smit, and M. Z. Krimer, Izv. Akad. Nauk SSSR, Ser. Khim. 2156 (1978).
2. W. N. Mueller and P. E. Butler, Chem. Commun., 648 (1966);
3. J. Org. Chem.,33, 2642 (1968).
4. G. Kresze and W. Kosbahn, Lieb. Ann. Chem.,731, 67 (1970).
5. G. H. Schmid and D. G. Garratt, The Chemistry of Double Bonded Functional Groups (S. Patai, ed.), Wiley (1977), p. 828.