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Conjugated iminium salts (III) and (V) are obtained by ene reaction of cyanamidium salt (I) with ylidenecyanamide derivatives (II) and (IV), respectively.

Glycosylation of pyridinone (IV) under conventional or microwave-assisted conditions affords the corresponding O-glycosides instead of the N-glycosides.

Title reaction leads to either 4H-1,3-oxazinium salts or 6H-1,3-oxazinium salt or N-acyl-1-azonia-1,3-butadiene salts . The formation of these products is explained by a multistep reaction sequence starting with a [2+2] cycloaddition of the carbonyl double bond to the nitrilium triple bond. The constitution of 6H-1,3-oxazinium hexachloroantimonate is confirmed by an X-ray structural analysis.

N-alkylnitrilium hexachloroantimonates 1 react with phenylacetylene (2 a) or bis(methylthio)acetylene (2f) to give 3-azonia-2,3,5-hexatriene hexachloroantimonates 4, which either enolize to furnish 4-alkylidene-2-methyl-6-phenyl-3-azonia-2,4-hexadiene salts 7d,e or cyclize to afford 3,4-bis(methylthio)-2H-pyrrolium salts 6f-k

N-Alkylnitrilium salts (1) undergo ene reactions with electron-rich di- and higher substituted alkenes 2 to afford either 2-azoniaallene salts (3, 6, 9, 11) (the nitrilium salt reacting as ene and the alkene reacting as enophile) or 1-azonia-1,4-pentadiene salts (10, 12) (the alkene reacting as ene and the nitrilium salt reacting as enophile). Competing with ene reactions tri- and tetrasubstituted alkenes and N-alkylnitrilium salts undergo [2+2]cycloaddition to furnish azetinium salts (8, 13). In solution, alkyl substituted 2-azoniaallene salts tautomerize to 2-azonia-1,3-butadiene salts (4, 5, 7). The constitutions of the 2-azoniaallene salt 6c and the azetinium salt 8 were secured by X-ray crystallographic analyses.

A new tetranortriterpenoid, 11 β ,12 β -diacetoxyharrisonin, together with the known atalantolide, obacunone, harrisonin, 12 β -acetoxyharrisonin, pedonin, cneorin R and perforaquassin A have been isolated from the root bark of Harrisonia abyssinica . The structure of the new compound which is based on a rearranged tetranortriterpenoid with a five membered ring-B and a seco ring-A and D was assigned on the basis of extensive NMR studies and X-ray diffraction analysis. In addition, the structure and relative configuration of the known perforaquassin A was confirmed by X-ray diffraction analysis.

Reactions of alpha,alpha'-dichloroazo compounds 2 with SbCl5 gave 1-(chloroalkyl)-1-aza-2-azoniaallene salts 3 as reactive intermediates. Cycloadditions of 3 with the ribofuranosyl cyanide 4 afforded the beta-D-ribofuranosyl-1,2,4-triazolium salts 5, which rearranged spontaneously to salts 6. Hydrolysis of 6 gave the 1,2,4-triazole C-nucleosides 7, which yielded the free nucleosides 8 after deblocking. Analogously, 12 was prepared from the cycloaddition of 4 with the alpha-chloroazo compound 10 in the presence of SbCl5. Deblocking of 12 with sodium methoxide afforded 13. Compounds 8a,b,e,f and 13 were tested against HIV-1, HIV-2, HSV-1 and HSV-2 and were found to be inactive.

The adenosine A2A receptor (AA2AR) has emerged as an attractive target for the treatment of Parkinson’s disease. Evidence suggests that antagonists of the AA2AR may be neuroprotective and may help to alleviate the symptoms of Parkinson’s disease. During last decade, many efforts have been accomplished searching potent and selective AA2AR antagonists. In this field, various xanthines and non-xanthine heterocyclic compounds of monocyclic, bicyclic and tricyclic nucleus possessing very good affinity with a broad range of selectivity have been proposed. The aim of this article is to summarize available data on different chemical classes of AA2AR antagonists including those in clinical development, and briefly present an overview of the structure–activity relationships found for these compounds. 1. Parkinson’s disease and its treatment

Interaction between 2,5-dichlorothiophene-3-carbonyl isothiocyanate, accessible via 2,5-dichlorothiophene-3-carbonyl chloride, and model heterocyclic amines produced the respective 2,5-dichloro-N-(substituted aminocarbonothioyl)thiophene-3-carboxamides. Upon heating, the deprotonated form of the latter underwent intramolecular cyclization to deliver the corresponding 2-(substituted amino)-4H-thieno[3,2-e]-1,3-thiazin-4-ones. The structures of these new bicyclic derivatives and their acyclic precursors are based on microanalytical and spectral (IR, MS, and NMR) data.

A series of N-(substituted)-6-chlorothieno[2,3-e]-1,4,2-dithiazin-3-amine 1,1-dioxides (9a-g) were prepared via direct interaction of the appropriate isothiocyanate with 2,5-dichloro-3-thiophenesulphonamide 6 in THF in the presence of sodium hydride. The structures of these new bicyclic derivatives are based on microanalytical and spectral (IR, MS, and NMR) data.