(E)-3-(2-Alkyl-10H-phenothiazin-3-yl)-1-arylprop-2-en-1-ones: Preparative, IR, NMR and DFT study on their substituent-dependent reactivity in hydrazinolysis and sonication-assisted oxidation with copper(II)nitrate

A series of novel 3(5)-aryl/ferrocenyl-5(3)-phenothiazinylpyrazoles and pyrazolines were obtained by substituent-dependent regioselective condensation of the corresponding (E)-3-(2-alkyl-10H-phenothiazin-3-yl)-1-aryl/ferrocenylprop-2-en-1-one with hydrazine or methylhydrazine in acetic acid. The dif...

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Bibliographic Details
Published in:Organic & biomolecular chemistry 2006-01, Vol.4 (23), p.4375-4386
Main Authors: Găină, Luiza, Csámpai, Antal, Túrós, György, Lovász, Tamás, Zsoldos-Mády, Virág, Silberg, Ioan A, Sohár, Pál
Format: Article
Language:English
Subjects:
Copper - chemistry
Cyclization
Hydrazines - chemistry
Magnetic Resonance Spectroscopy
Nitrates - chemistry
Oxidation-Reduction
Phenothiazines - chemical synthesis
Phenothiazines - chemistry
Pyrazolones - chemistry
Sonication
Spectrophotometry, Infrared
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Summary:A series of novel 3(5)-aryl/ferrocenyl-5(3)-phenothiazinylpyrazoles and pyrazolines were obtained by substituent-dependent regioselective condensation of the corresponding (E)-3-(2-alkyl-10H-phenothiazin-3-yl)-1-aryl/ferrocenylprop-2-en-1-one with hydrazine or methylhydrazine in acetic acid. The different propensity of the primary formed beta-hydrazino adducts to undergo competitive retro-Mannich reaction was interpreted in terms of tautomerisation equilibrium constants calculated by DFT using a solvent model. The regioselectivity of the cyclisation reactions with methylhydrazine and the substituent-dependent redox properties of pyrazolines were also rationalized by comparative DFT calculations performed for simplified model molecules. On the effect of ultrasound-promoted oxidation with copper(II)nitrate phenothiazine-containing pyrazolines, enones and oxo-compounds were selectively transformed into sulfoxides. Only one sulfoxide enone was partially converted into an oxirane derivative. The structure of the novel products was determined by IR and NMR spectroscopy including COSY, HSQC, HMBC and DNOE measurements.
ISSN:1477-0520
1477-0539
DOI:10.1039/b608455a