C−H Activation and Cross‐Coupling of Acyclic Aldonitrone. Issue 5 (26th January 2021)

• Record Type: Journal Article
• Authors: Brześkiewicz, Jakub; Stańska, Barbara; Dąbrowski, Piotr; Loska, Rafał
• Is Part Of: European journal of organic chemistry. Issue 5(2021)
• Page Start: 814
• Page End: 824
• Publication Date: 2021-01-26
• Subjects: Catalysis -- C−H activation -- Cross-coupling -- Homogenous nitrones -- Isomerization; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202001496
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: Palladium‐catalyzed activation of C(sp 2 )−H bond in a readily E, Z ‐isomerizable aldonitrone, bearing an ester group at the C terminus, enabled its cross‐coupling with a variety of aryl and heteroaryl bromides to give ketonitrones, including products with functional groups not compatible with the classical nitrone synthesis via condensation with hydroxylamines. The reactions proceeded with very high (usually complete) E selectivity. The key to obtaining good yields of the cross‐coupling products was the use of sterically hindered carboxylic acid as additive and non‐polar solvent (toluene), in which the starting nitrone exists mainly as E isomer. Further use of the obtained ketonitrones in dipolar cycloaddition or nucleophilic addition has also been demonstrated. Abstract : Palladium‐catalyzed C(sp 2 )−H activation of an acyclic, glyoxalate‐derived aldonitrone and its cross‐coupling with a variety of aryl and heteroaryl bromides provides C ‐aryl ketonitrones with very high E selectivity.