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

Abstract

A new Pd(II)-catalyzed annulation/iododifluoromethylation of enynones has been developed for the synthesis of versatile 1-indanones with moderate to good yields (26 examples). The present strategy enabled the concomitant incorporation of two important difluoroalkyl and iodo functionalities into 1-indenone skeletons with (E)-stereoselectivity. The mechanistic pathway was proposed, consisting of the difluoroalkyl radical-triggered α,β-conjugated addition/5-exo-dig cyclization/metal radical cross-coupling/reductive elimination cascade.

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.…”

Photoinduced Alkylsulfonylation and Cyanoalkylsulfonylation of Morita–Baylis–Hillman Adducts via Multicomponent Insertion of Sulfur Dioxide

“…Encouraged by this result, we questioned whether S N 2′-type alkylsulfonylation of MBH adducts could be achieved by combining of alkyl carbon radical and SO 2 under visible light catalysis and mild conditions. Based on our continued interest in radical chemistry and expanding the molecular diversity of allylic sulfones, we reported herein the first example for the assembly of allylic alkylsulfones 3 through a visible light induced multicomponent reaction of MBH adducts 1 , SO 2 surrogate of DABSO, and potassium alkyltrifluoroborates 2 in the presence of Mes-Acr + ClO 4 – (Scheme e path i ). Notably, when cycloketone oxime esters served as C-radical precursors to expand the diversity of allyl alkylsulfonylation MBH adducts, the cyanoalkylsulfonylation reaction of MBH adducts 1 with DABSO and cycloketone oxime esters 4 proceeded smoothly in the presence of a photoredox catalyst with N , N , N ′, N ′-tetramethylethylenediamine (TMEDA) as a base, orienting similar processes entry to synthesize trisubstituted olefins 5 bearing a alkyl sulfonyl unit and a cyano group (Scheme e path ii ).…”

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).…”