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Synthesis, Molecular Structure and Reactivity of 5-Methylidene-1,2,3,5-tetrahydroimidazo[2,1-b]quinazolines

Author(s): Anita Kornicka | Franciszek Sączewski | Maria Gdaniec

Journal: Molecules ISSN 1420-3049
Volume: 9; Issue: 3; Start page: 86; Date: 2004;
Original page

Keywords: 5-Methylidene-1 | 2 | 3 | 5-tetrahydroimidazo[2 | 1-b]quinazolines | 1 | 3-dipolar cycloaddition | alkylation | acylation | X-ray structure analysis.

ABSTRACT
Synthesis of novel 5-methylidene-1,2,3,5-tetrahydro[2,1-b]-quinazolinederivatives 2-4 with potential biological activities mediated by α-adrenergic and/orimidazoline receptors was performed by reacting 2-chloro-4,5-dihydroimidazole (1) withthe corresponding 2-aminoacetophenones. Compound 2, which incorporates an enaminemoiety, underwent a 1,3-dipolar cycloaddition reaction with the appropriate nitrones 5-9to give 1,2,3,5-tetrahydro-imidazo[2,1-b]quinazolin-5,5'-spiro-2',3'-diphenylisoxazol-idines 10-14. Reactions of the title compounds 2 and 4 with dimethyl acetylene-dicarboxylate (DMAD) afforded dimethyl 2-(2,3-dihydroimidazo[2,1-b]quinazolin-5(1H)-ylidenemethyl)but-2-enedioates 15, 16. Imidazo[2,1-b]quinazoline 2 was furthertreated with acetyl chloride, benzoyl chloride and mesyl chloride to give the 1-substitutedderivatives 17, 18 and 19, respectively. The structures of all new compounds obtainedwere confirmed by elemental analysis and spectral data (IR, 1H- and 13C-NMR) as well asX-ray crystallographic analysis of 3 and 18.