1. Y. Iwanami, Nippon Kagaku Zasshi, 83, 161 (1962); C. A., 59, 3920b (1963).
2. N. G. Koshel and I. Ya. Postovskii, KhGS [Chemistry of Heterocyclic Compounds], 6, 684 (1970).
3. A. Bantlin, Ber., 11, 2106 (1878).
4. L. Horner, U. Schwenk, and E. Junghans, Ann., 579, 212 (1953).
5. K. T. Potts and S. W. Schneller, J. Heterocycl.Chem., 1968, 469.