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We have synthesized several bicyclic heteroaromatic compounds with bridgehead nitrogen from N-amine salts of heteroaromatic amines. 2-Amino and 2-unsubstituted thiazolo[3,2-b][l,2,4]triazole derivatives 2a-b were prepared by the cyclization reaction from N-amine salts of aminothiazole-5-yl(N-methoxyimino)acetate with cyanogen bromide and formamidine acetic acid salt, respectively. 2-Methylthiazolo[3,2-b][1,2,4]triazole 2c was obtained from N-acetylated N-amine salt of aminothiazole-5-yl(N-methoxyimino)acetate by the cyclization reaction in the presence of polyphosphoric acid (PPA). 2-Substituted and 2-unsubstituted thiazole[3,2-b][1,2,4]triazole derivatives 2a-c were coupled with 7-aminocephalosporanic acid (7-ACA). Coupled cephalosporin derivatives 1a-c did not have good antibacterial activities in vitro.

The syntheses and in vitro evaluation of a new series of pyrido[2,3-d]pyrimidine-2,4-diones bearing substituents at C-3 and/or C-4 positions on the pyridine ring are described. Some of these compounds, especially 5l and 6f, were found to be potent phosphodiesterase 4 (PDE 4) inhibitors exhibiting improved ratio of PDE 4 inhibitory activity:rolipram binding assay (RBA).

The indium-mediated allylation reaction of acyl cyanides with allyl halides in aqueous media afforded a variety of β,γ-unsaturated ketones in moderate to good yields under mild and neutral conditions.

We review in this report the preparation of several side-chain fluorinated analogues of biologically important imidazoles and indoles. The building blocks used should also have applications in other synthetic problems. The addition of “FBr” to vinyl imidazole derivatives was used to prepare β-fluoro- and β,β-difluorohistamine and histidinols, as well as β-fluorourocanic acid. Deoxyfluorination of intermediate acylindoles was used to prepare a series of β,β-difluorotryptamine derivative, including the fluorinated analogue of the important neurotransmitter, serotonin.

The reductive cleavage of thiobenzoates promoted by samarium diiodide afforded various kinds of disulfides in good yields under mild and neutral conditions.

Cephalosporins with 3-pyazolylpyridinium at C-3 position, which is supposed to exhibit synergic activity of ceftazidime and cefoselis, were synthesized and their antibacterial activity against Gram-positive and Gram-negative was inspected.

The new cephalosporins having N-linked quarternary ammonium salt at C-3 position were prepared from the reaction of 2-methylimino-3-methyl-1,3-thiazoline derivatives with cephalosporins. Also antimicrobial activities of those compounds were determined.