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DOI: 10.1055/s-2001-9745
Studies on Isocyanides and Related Compounds; A Facile Synthesis of 4-Phenyl-1-(2H)phthalazinone-2-alkanoic Acid Amides
Publication History
Publication Date:
31 December 2001 (online)

A convenient synthesis of the title compounds by means of the Ugi four-component condensation (Ugi 4-CC) is reported. The reaction between acetaldehyde azine (3a), 2-benzoylbenzoic acid (4),and cyclohexyl isocyanide (5) spontaneously afforded N-cyclohexyl 2-(1,2-dihydro-1-oxo-4-phenylphthalazin-2-yl)propionamide (1a) upon loss of acetaldehyde from the intermediate Ugi 4-CC adduct 6a. Starting from the less reactive azines 3c-f arising from ketones, the Ugi 4-CC adducts 6c-f did not spontaneously cyclize, whereas phenylacetaldehyde azine (3b) afforded a mixture of the Ugi 4-CC adduct 6b and cyclized product 1b. In all of the cases, the adducts 6b-f were easily cyclized to 1b-f in acidic medium.
isocyanides - multi-component reactions - Ugi four-component condensation (U-4CC) - 1-(2H)phthalazinones - phthalazine ring synthesis