Ugi-post functionalization, from a single set of ugi-adducts to two distinct heterocycles by microwave-assisted palladium-catalyzed cyclizations: tuning the reaction pathways by ligand switch. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Organic Chemistry Année : 2009

Ugi-post functionalization, from a single set of ugi-adducts to two distinct heterocycles by microwave-assisted palladium-catalyzed cyclizations: tuning the reaction pathways by ligand switch.

William Erb
Luc Neuville

Résumé

Linear amides 4, prepared in one step by the Ugi four-component reaction, were converted to 3,4-dihydroquinoxalin-3-ones (5) or to 2-(2-oxoindolin-1-yl)acetamides (6) dependent on the catalytic conditions. While microwave irradiation was found to be determinant on the reaction efficiency, the choice of ligand diverged the reaction pathways. Heating a solution of 4 in dioxane/MeCN (v/v = 85/15) under microwave irradiation conditions in the presence of Pd(dba)(2) (0.05 equiv) and Cs(2)CO(3) (2 equiv), using XPhos as a supporting ligand, afforded the 3,4-dihydroquinoxalin-3-ones (5) via an intramolecular N-arylation of the secondary amide. On the other hand, using BINAP as ligand under otherwise identical conditions, intramolecular alpha-CH arylation of tertiary amide occurred to furnish the oxindoles (6).
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Dates et versions

hal-00416555 , version 1 (14-09-2009)

Identifiants

Citer

William Erb, Luc Neuville, Jieping Zhu. Ugi-post functionalization, from a single set of ugi-adducts to two distinct heterocycles by microwave-assisted palladium-catalyzed cyclizations: tuning the reaction pathways by ligand switch.. Journal of Organic Chemistry, 2009, 74 (8), pp.3109-15. ⟨10.1021/jo900210x⟩. ⟨hal-00416555⟩
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