2,3‐Dichloro‐5,6‐dicyano‐1,4‐benzoquinone Mediated Tandem Oxidative‐Coupling/Annulation of Enaminones with 1,3‐Diarylpropenes for the Synthesis of 3‐Allylchromones

Abstract

The tandem reaction of enaminones with 1,3‐diarylpropenes mediated by 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) is reported, which involves the oxidative coupling and the intramolecular cyclization reactions. It provides a convenient, efficient and metal‐free method for the synthesis of 3‐allylated chromones and quinolone with potential biological activities.

Synthetic applications of hydride abstraction reactions by organic oxidants

“…Other nucleophiles can be used to add into diarylpropene-derived cations, including indole, 60 phosphites, 61 and enaminones. 62 Cheng and co-workers expanded the diarylpropene chemistry in the development of processes that employ consecutive oxidations. 63 This is illustrated (Scheme 17) by the coupling of 76 with enamino ester 79.…”

Recent advances in the synthesis of 4H-chromen-4-ones (2012 − 2021)

“…286 Gold(I)-catalyzed hydroxy group assisted C(sp 2 )dH alkylation of o-hydroxyaryl enaminones with diazo compounds in dichloromethane at 60 °C gave 3-CH substituted 4H-chromen-4-ones, in good yields. 287 DDQ mediated tandem oxidative-coupling/annulation reactions of o-hydroxyaryl enaminones with 1,3-diarylpropenes to obtain 3-(1,3-diarylprop-2-en-1-yl)-4H-chromen-4-ones 288 and with cycloheptatriene to produce 3-(cycloheptatrienyl)-4H-chromen-4-ones, 289 in 1,2-DCE at room temperature. Several 3-vinyl-4H-chromen-4-ones were formed via domino C-H alkenylation and annulation reaction of o-hydroxyaryl enaminones with both terminal and internal alkenes promoted by palladium and iodide catalysts in the presence of TBHP and sodium bicarbonate in 1,2-DCE at 110 °C.…”

Six-membered ring systems: with O and/or S atoms

“…The synthesis of 3-fluoro-4H-chromen-4-ones is accomplished through tandem cyclization reactions of enaminones, prepared from the reaction of 2 0 -hydroxyacetophenones with N,N-dimethyl formamide dimethyl acetal (DMF-DMA) in refluxing toluene, promoted by Selectfluor in DCE at room temperature (19SL2295). It is through DDQ-promoted tandem oxidativeecoupling/annulation reactions that enaminones react with 1,3-diarylpropenes in DCE to afford 3-(1,3-diarylprop-2-en-1-yl)-4H-chromen-4-ones, in moderate to good yields (19EJO4589). A range of 3-methylthio-4H-chromen-4-ones are produced from iodine-promoted multicomponent reaction of 2 0 -hydroxyacetophenones with rongalite and DMSO carried out in the presence of DBU and copper(II) oxide at 100 C (Scheme 71) (19OBC1535).…”