Access to Variously Substituted 5,6,7,8-Tetrahydro-3H-quinazolin-4-ones via Diels–Alder Adducts of Phenyl Vinyl Sulfone to Cyclobutene-Annelated Pyrimidinones

Autor: Dirk Finsinger, Suryakanta Dalai, Armin de Meijere, Karsten Rauch, Vladimir N. Belov, Shamil Nizamov
Rok vydání: 2006
Předmět:
Zdroj: European Journal of Organic Chemistry. 2006:2753-2765
ISSN: 1099-0690
1434-193X
DOI: 10.1002/ejoc.200600060
Popis: Under basic conditions (Et3N, dioxane), the aromatic amidines 4 and also S-methylisothiourea 4g cleanly undergo Michael addition to methyl 2-chloro-2-cyclopropylideneacetate (5), followed by intramolecular nucleophilic substitution, cyclopropyl to cyclobutyl ring enlargement, deprotonation and cyclization with elimination of methanol to afford the cyclobutene-annelated pyrimidinones 6 in 43–83 % yield (7 examples). Thermal cyclobutene-ring opening of the latter at 175 °C followed by regioselective Diels–Alder cycloaddition with phenyl vinyl sulfone gives the 2-aryl-6-(phenylsulfonyl)-5,6,7,8-tetrahydroquinazolinone derivatives 12 in 39–83 % yield (7 examples). Base-induced elimination of benzenesulfinic acid and subsequent catalytic hydrogenation leads to the 2-aryltetrahydroquinazolinone derivatives 14 in excellent yields (6 examples). Deprotonation at the sulfonyl-substituted center, alkylation and subsequent elimination of benzenesulfinic acid followed by catalytic hydrogenation gives the 2,6-disubstituted tetrahydroquinazolinones 17a-R. Nucleophilic substitution of the methylthio group in 12g by secondary amines yields the 2-(dialkylamino)tetrahydroquinazolinones 14i–k.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Databáze: OpenAIRE
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