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One-pot synthesis of 6-pyrrolyl- N -alkyl-indazoles by the reductive coupling of N -alkyl-6-nitroindazoles and 2,5-hexadione was investigated in the presence of different reducing agents (SnCl 2 /AcOH and In/AcOH in THF). Indazoles 5a – h and 6a – h were obtained in good to excellent yields (74–95%) and characterized by elemental analysis, NMR, and single crystal X-ray diffraction. The same synthetic approach was also used to obtain 5-pyrrolyl- N -alkyl-indazoles.

New four-substituted indazoles 4a–e were synthesized by regioselective nucleophilic substitution of hydrogen of N-alkyl-7-nitroindazoles 2a,b with arylacetonitriles 3a–c. Compounds 4a–e were reacted with arylsulfonyl chloride in pyridine to give some new indazole linked sulfonamides with good yields. The SNH at position C-4 of 7-nitroindazole with arylacetonitrile is confirmed by X-ray diffraction analysis of compounds 4e and 6a.

The reduction of substrate (I) in the presence of alcohols affords the corresponding amines and the unexpected title compounds (III).

The synthesis of 3-glycosyloxylated flavylium ions (anthocyanins), in particular of callistephin (4), a natural anthocyanin, is described. The structural transformations in aqueous solution and molecular complexation with chlorogenic acid (7) and caffeine (8) of the synthesized pigments 3 and 4 are investigated and compared to those of the corresponding 3-methoxyflavylium ions 1 and 2 and to those of oenin (5) and malvin (6), two very common natural anthocyanins. The results are discussed in terms of the role played by the glycosyloxy residues in the chemical properties of anthocyanins. Anthocyanin molecular complexation (copigmentaion) is quantitatively investigated by UV/VIS spectroscopy and 1H-NMR. In particular, the UV/VIS spectroscopic data are interpreted using a general theoretical treatment, which, e.g., allows to demonstrate the formation of molecular complexes between the colourless forms of an anthocyanin and 8.