... [a] Department of Chemistry, [b] Center of Analysis and Measurement, Zhongshan University, Guangzhou 510275 PR China; [c] Department of Chemistry and Biochemistry ... Chem. Soc., 33, 455 (1956). [24] G. Kototos and C. Tzougraki, J. Heterocyclic Chem., 23, 87 (1986). ...