Synthesis of (E)-Quinoxalinone Oximes through a Multicomponent Reaction under Mild Conditions

Abstract

Herein, a novel method for the gram-scale synthesis of (E)-quinoxalinone oximes through a multicomponent reaction under mild conditions is described. Such a transformation was performed under transition-metal-free conditions, affording (E)-oximes in a moderate-to-good yield through recrystallization. Our methodology demonstrates a successful combination of a Mannich-type reaction and radical coupling, providing a green and practical approach for the synthesis of potentially bioactive quinoxalinone-containing molecules.

Photoinduced Protocol for Aerobic Oxidation of Aldehydes to Carboxylic Acids under Mild Conditions

“…Shen and co-workers demonstrated a photoinduced self-catalyzed fluoroalkylation/cyclization of unactivated alkenes using molecular oxygen as a green oxidant . On the other hand, great effort has been devoted to developing aqueous phase reactions because water serves as an abundantly available, non-toxic, and non-flammable solvent. − Based on our previous work on developing green and sustainable reaction systems for organic synthesis, − herein, we report a photoinduced aerobic aqueous-phase reaction for the oxidation of aldehydes (Scheme b). Such a transformation employs molecular oxygen (O 2 ) as the sole oxidant and water as the main solvent and avoids using any catalyst and additive, providing a green and practical approach for the preparation of carboxylic acids.…”

Recent advances in the application of Langlois’ reagent in olefin difunctionalization

“…1 Consequently, the development of efficient methods for incorporation of CF 3 groups into organic molecules remains a topic of intensive research to the scientific community. 2 The introduction of a CF 3 group into organic molecules has been quite prominent in the last decade, which was due to the discovery of multifarious trifluoromethylation reagents. 3 Based on the type of active intermediate derived from substrates, 4 they fall into the following four categories (Scheme 1a), (a) electrophilic trifluoromethylation reagents, such as Togni's reagent, (b) nucleophilic trifluoromethylation reagents, such as the Ruppert–Prakash reagent, (c) radical trifluoromethylation reagents, such as (bpy)Cu(CF 3 ) 3 , and (d) trifluoromethyl radical reagents, such as Langlois’ reagent.…”

Visible-light-induced direct perfluoroalkylation/heteroarylation of [1.1.1]propellane to diverse bicyclo[1.1.1]pentanes (BCPs) under metal and photocatalyst-free conditions

“…8 Recently, our group has reported several photocatalyst-free protocols for the modification of heteroarenes. 9 These multi-component transformations proceed via a radical-relay mechanism to generate the desired products. In consideration of the facts that [1.1.1]propellane involves a characteristic fragile central bond (energy barrier of ring opening: ∼26 kcal mol −1 ) and the bicyclo[1.1.1]pentyl radical (BCP-radical) is kinetically stable, 10 we wondered whether it might be possible to intercept the strained [1.1.1]propellane with perfluoroalkyl radicals.…”