Copper-Catalyzed Annulation–Trifluoromethyl Functionalization of Enynones

Abstract

The Cu­(I)-catalyzed annulation–halotrifluoromethylation and cyanotrifluoromethylation of enynones have been established, enabling multibond formations of the synthesis of quaternary carbon-centered 1-indanones in moderate to good chemical yields. The reaction of enynones with Togni’s reagent and chloro- or bromotrimethylsilane afforded halo- and CF3-containing 1-indenones. However, the addition of K3PO4 as a base into the catalytic system led to forming cyano-anchored (Z)-1-indanones as major stereoisomeric products. This strategy exhibits remarkable compatibility with a wide range of enynones.

Photoinduced radical tandem annulation of 1,7-diynes: an approach for divergent assembly of functionalized quinolin-2(1H)-ones

“…Recently, Jiang's group elaborated a photocatalytic three-component biheterocyclization of heteroatom-linked 1,7-diynes with CBrCl 3 and water as oxygen sources, leading to access of skeletally diverse fusedtricyclic heterocycles (Scheme 1C) (Wang et al, 2021). Intrigued by previous work and the continuation of our interest in radical cascade reactions (Wang et al, 2023a;Wang et al, 2023b;Wang et al, 2023c;Zhang et al, 2023), we believed that CCl 3 radical derived from BrCCl 3 under visible-light irradiation could add to preformed amide-linked 1,7-diynes followed by 6-exo-dig cyclization, 1,5-(S N ″)-substitution, and dehydrohalogenation to furnish versatile functionalized quinolin-2(1H)-ones. No construction of quinolin-2(1H)-ones bearing gem-dihaloalkenes starting from 1,7-diynes and perhalogenated methanes has been reported.…”

Catalytic Radical-Triggered Annulation/Iododifluoromethylation of Enynones for the Stereospecific Synthesis of 1-Indenones

“…Enynones are known compounds that have been reported. We prepared them according to literature procedures . Other reagents, unless otherwise noted, were purchased from commercial vendors and used without further purification.…”

“…Many methods for the construction of 1-indenones have been established, which often involve classical Friedel–Crafts acylation, Grignard reagent-initiated reactions, Heck–Larock cyclization, as well as metal-catalyzed annulation of arylalkynes and recently developed radical addition–cyclization strategy . Very recently, Zhu’s lab reported a novel kind of enynones and applied them to [4 + 2] annulations with styrenes and 1,4-conjugate addition with electron-rich aromatic compounds . We and collaborators have also developed a number of powerful and efficient pathways for the construction of 1-indenone frameworks via radical-induced annulation-difunctionalization of 1,6-enynes .…”

Photocatalytic Multicomponent Annulation of Amide-Anchored 1,7-Diynes Enabled by Deconstruction of Bromotrichloromethane

“…For instance, the group of Jiang elaborated a photocatalytic three-component biheterocyclization of heteroatom-linked 1,7-diynes with CBrCl 3 and water, leading to access skeletally diverse fused-tricyclic heterocycles [ 38 ]. Encouraged by previous results and the continuation of our interest in synthetic chemistry [ 44 , 45 , 46 , 47 ], we planned and conceived that the reaction can be directed toward photoinduced addition-annulation to build up quinolone skeletons when secondary alcohol-tethered 1,7-diynes was changed by amide-anchored 1,7-diynes as radical receptors. Intriguingly, we found the multicomponent cyclization reaction of amide-anchored 1,7-diynes 1 with CBrCl 3 , H 2 O and alcohols/thiols under visible-light irradiation, producing a plethora of 3-benzoyl-quinolin-2(1 H )-one acetates 2 in moderate to excellent yields ( Scheme 1 b).…”