Synthesis of Polycyclic Benzo[<i>b</i>]indolo[3,2,1-<i>de</i>]acridines via Sequential Allenylation, Diels–Alder Cyclization, and Hydrogen Migration Reaction

A novel methodology for stereoselective synthesis of benzo­[<i>b</i>]­indolo­[3,2,1-<i>de</i>]­acridines through the tandem reaction of propargylic compounds with organoboron is described, and only one diastereoisomer was obtained. The sequential procedure was triggered by Pd(0)-catalyzed allenylation of propargyl carbonate. Then, Diels–Alder cyclization and hydrogen migration processes proceeded successively to furnish the polycyclic target molecules. Control reactions suggested the base (Cs₂CO₃) was indispensable for the hydrogen migration

LDA-Promoted Synthesis of 3‑Amino Furans by Selective Lithiation of Enaminones

An efficient cascade β-metalation/addition/cyclization reaction promoted by LDA is described in which 3-amino furans were constructed from enaminones and aldehydes. A broad range of substituents on the starting compounds was tolerated, and the polysubstituted furans were gained with moderate to excellent yields within 2 h

Palladium-Catalyzed Synthesis of 2,3,4-Trisubstituted Furans via Cascade Reactions of Aryloxy-enynes with Aryl Halides

A highly efficient palladium-catalyzed cascade reactions of aryloxy-enynes with aryl halides under mild reaction conditions has been developed. This methodology offers rapid access to 2,3,4-trisubstituted furans in good to excellent yields in a regioselective manner

Lewis Acid-Catalyzed Cyclization of Enaminones with Propargylic Alcohols: Regioselective Synthesis of Multisubstituted 1,2-Dihydropyridines

A highly efficient BF₃·Et₂O-catalyzed cascade reaction of enaminones with propargylic alcohols under mild reaction conditions has been developed. This methodology offers regioselective access to multisubstituted 1,2-dihydropyridines in good to excellent yields

Palladium-Catalyzed Synthesis of 2,3,4-Trisubstituted Furans via Cascade Reactions of Aryloxy-enynes with Aryl Halides

A highly efficient palladium-catalyzed cascade reactions of aryloxy-enynes with aryl halides under mild reaction conditions has been developed. This methodology offers rapid access to 2,3,4-trisubstituted furans in good to excellent yields in a regioselective manner

Lewis Acid-Catalyzed Cyclization of Enaminones with Propargylic Alcohols: Regioselective Synthesis of Multisubstituted 1,2-Dihydropyridines

A highly efficient BF₃·Et₂O-catalyzed cascade reaction of enaminones with propargylic alcohols under mild reaction conditions has been developed. This methodology offers regioselective access to multisubstituted 1,2-dihydropyridines in good to excellent yields

Copper-Catalyzed Oxidative Dearomatization/Spirocyclization of Indole-2-Carboxamides: Synthesis of 2‑Spiro-pseudoindoxyls

A copper-catalyzed oxidative dearomatization/spirocyclization of indole-2-carboxamides using <i>tert</i>-butyl hydroperoxide (TBHP) as the oxidant has been developed that provides rapid and efficient access to C2-spiro-pseudoindoxyls. Two of the sp² C–H bonds are functionalized during the reaction process, and the reaction likely proceeds via the formation of a highly reactive 3<i>H</i>-indol-3-one intermediate followed by aromatic electrophilic substitution with the <i>N</i>-aryl ring of the amide moiety

Transition-Metal-Free Aminoacylation of Ynones with Amides: Synthesis of 3‑Carbonyl-4-quinolinones or Functionalized Enaminones

A transition-metal-free tandem process for the synthesis of substituted quinolin-4­(1<i>H</i>)-ones or enaminones is presented. A base-promoted insertion of ynones into the C–N σ-bond of amides is the key step in this process, which provides the corresponding aminoacylation products in good to high yields. Quinolin-4­(1<i>H</i>)-ones are selectively formed via the subsequent N-cyclization pathway in the cases of ynones bearing an <i>ortho</i>-bromo-substituted aryl ring. Easily accessible starting materials and high atom economy make this procedure attractive

Copper-Catalyzed Synthesis of Substituted Quinolines via C–N Coupling/Condensation from <i>ortho</i>-Acylanilines and Alkenyl Iodides

An efficient cascade copper-catalyzed intermolecular Ullmann-type C–N coupling/enamine condensation reaction is described, in which <i>ortho</i>-acylanilines and alkenyl iodides converted to multisubstituted quinolines in good to excellent yields

Transition-Metal-Free Ring Expansion Reactions of Indene-1,3-dione: Synthesis of Functionalized Benzoannulated Seven-Membered Ring Compounds

A novel ring expansion reaction of indene-1,3-dione with alkynyl ketones under transition-metal-free conditions has been developed. This process offers an efficient and direct way to synthesize benzoannulated seven-membered rings or fused-ring compounds through C–C σ-bond activation. Notable features of the procedure include easily accessible starting materials, good functional group tolerance, and high atom economy