1. M. J. Weiss, G. J. Gibs, J. F. Poletto and W. A. Remers, US Patent 3,758,501 (1973);
2. Chem. Abstr., 82, P57663r (1974).
3. R. C. Effland, L. Davies and G. C. Helsley, US Patent 3,952,025 (1976);
4. Chem. Abstr., 85, P46628u (1976).
5. Intramolecular Reactions of Some Cyclic β-Diketones1