Studies on Isocyanides and Related Compounds; A Facile Synthesis of 4-Phenyl-1-(2H)phthalazinone-2-alkanoic Acid Amides

Stefano Marcaccini; Roberto Pepino; Cecilia Polo; M. Cruz Pozo

doi:10.1055/s-2001-9745

Synthesis 2001; 2001(1): 0085-0088
DOI: 10.1055/s-2001-9745

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Studies on Isocyanides and Related Compounds; A Facile Synthesis of 4-Phenyl-1-(2H)phthalazinone-2-alkanoic Acid Amides

Stefano Marcaccini^* , Roberto Pepino, Cecilia Polo, M. Cruz Pozo

^*CNR, Centro di Studio sulla Chimica e la Struttura dei Composti Eterociclici e loro Applicazioni, Dipartimento di Chmica Organica "Ugo Schiff", Università di Firenze, via Gino Capponi 9, 50121 Firenze, Italy; E-mail: marc@chimorg.unifit.it

Abstract

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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

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