Visible-Light-Promoted Tandem Annulation of <i>N</i>‑(<i>o</i>‑Ethynylaryl)acrylamides with CH₂Cl₂

A novel tandem annulation of <i>N</i>-(<i>o</i>-ethyn­yl­aryl)­acryl­amides, with CH₂Cl₂ as a one-carbon unit, for the divergent synthesis of cyclopenta­[<i>c</i>]­quinolin-4­(<i>5H</i>)-ones and benzo­[<i>j</i>]­phenanthridin-6­(<i>5H</i>)-ones, which relies on the substitution effect of the 2 position of the acrylamide moiety, is described. Promoted by the visible-light photoredox catalysis, this reaction allows the formation of multiple chemical bonds through multiple C–Cl/C–H functionalization and [2 + 2 + 1] annulation cascades

Metal-Free Oxidative 1,2-Arylmethylation Cascades of <i>N</i>‑(Arylsulfonyl)acrylamides Using Peroxides as the Methyl Resource

A new, metal-free oxidative 1,2-arylmethylation cascades of <i>N</i>-(arylsulfonyl)­acrylamides for the assembly of 2,2-disubstituted-<i>N</i>-arylbutanamides containing an all-carbon quaternary center is presented. This reaction enables the one-step formation of two new C–C bonds through a sequence of methylation/1,4-aryl migration/desulfonylation using an organic peroxide as the methyl resource with a broad substrate scope and excellent functional group tolerance

Palladium-Catalyzed Oxidative Heck-Type Alkylation/Aryl Migration/Desulfonylation between Alkenes with α‑Carbonyl Alkyl Bromides

A new Pd­(II)-catalyzed alkene oxidative difunctionalization initiated by Heck insertion has been developed for the selective synthesis of acyclic and cyclic all-carbon quaternary stereocenters, which achieves an oxidative Heck-type alkylation, aryl migration, and desulfonylation sequence and represents a different input from those previously used Heck coupling in synthesis is reported

[4 + 2] Annulation Cascades of 2‑Bromo-1-arylpropan-1-ones with Terminal Alkynes Involving C–Br/C–H Functionalization

Straightforward access to various substituted naphthalenones by copper-catalyzed [4 + 2] annulation cascades of 2-bromo-1-arylpropan-1-ones with terminal alkynes is presented. Employing a Cu­(MeCN)₄PF₄ catalyst and 1,10-phenanthroline (1,10-Phen) ligand enables the formation of three new C–C bonds in a single reaction via [4 + 2] annulation of a 2-bromo-1-arylpropan-1-one with an alkyne followed by α-alkylation with the other 2-bromo-1-arylpropan-1-one with excellent functional group tolerance and step efficiency

Sulfur Incorporation: Copper-Catalyzed Cascade Cyclization of 1,7-Enynes with Metal Sulfides toward Thieno[3,4‑<i>c</i>]quinolin-4(<i>5H</i>)‑ones

A novel copper-catalyzed cascade cyclization of 1,7-enynes with metal sulfides is described. This sulfur-incorporation method provides straightforward access toward the important thiophene-fused quinolin-4­(<i>5H</i>)-one scaffold through cyclization and double C–S bond formation cascade, and the chemoselectivity of this 1,7-enyne cyclization toward 1,3,3a,9b-tetrahydrothieno­[3,4-<i>c</i>]­quinolin-4­(<i>5H</i>)-ones and 3,3a-dihydrothieno­[3,4-<i>c</i>]­quinolin-4­(<i>5H</i>)-ones can be controlled by varying the sulfur resources

Rhodium-Catalyzed Synthesis of Isoquinolines and Indenes from Benzylidenehydrazones and Internal Alkynes

A new route is presented for the selective assembly of isoquinolines and indenes by rhodium-catalyzed tandem cyclization of benzylidenehydrazones with internal alkynes. This method involves the selective cleavage of the N–N bond and the CN bonds and is dependent on the substituents of the benzylidenehydrazone

Metal-Free Oxidative <i>Ipso</i>-Carboacylation of Alkynes: Synthesis of 3‑Acylspiro[4,5]trienones from <i>N</i>‑Arylpropiolamides and Aldehydes

A general and metal-free radical route to synthesis of 3-acylspiro­[4,5]­trienones is established that utilizes TBHP (<i>tert</i>-butyl hydrogenperoxide) as an oxidation and a reaction partner to trigger the oxidative <i>ipso</i>-carboacylation of <i>N</i>-arylpropiolamides with aldehydes. This method offers a new difunctionalization of alkynes through oxidative cross coupling of the aldehyde C­(sp²)–H bond with an <i>ipso</i>-aromatic carbon

Copper-Catalyzed Radical [2 + 2 + 1] Annulation of Benzene-Linked 1,<i>n</i>‑Enynes with Azide: Fused Pyrroline Compounds

A novel selective copper-catalyzed radical [2 + 2 + 1] annulation of benzene-linked 1,<i>n</i>-enynes with azido-benziodoxolone to access fused pyrroline compounds, including 3<i>H</i>-pyrrolo­[3,4-<i>c</i>]­quinolin-4­(3<i>aH</i>)-ones, chromeno­[3,4-<i>c</i>]­pyrrol-4­(9<i>bH</i>)-one, and indeno­[1,2-<i>c</i>]­pyrroline, has been developed, which proceeds via the addition of the azide radical to the alkene, annualtion, and azidation cascade

Copper-Catalyzed C–H Oxidative Radical Functionalization and Annulation of Aniline-Linked 1,7-Enynes: Evidence for a 1,5-Hydride Shift Mechanism

A new copper-catalyzed tandem C–H oxidative radical functionalization and annulation of aniline-linked 1,7-enynes with alkyl nitriles or acetone is described. This reaction allows the selective construction of 1<i>H</i>-cyclopenta­[<i>c</i>]­quinolines and benzo­[<i>j</i>]­phenanthridin-6­(5<i>H</i>)-ones which rely on the substitution effect at the 2-position of the acrylamide moiety. The mechanism involving a 1,5-hydride shift process is proposed according to the control deuterium-labeled experiment

Synthesis of Benzocyclohepta[<i>b</i>]indoles by Lewis Acid Catalyzed Annulation of Two 3‑(1<i>H</i>‑Isochromen-1-yl)‑1<i>H</i>‑indoles

A novel Lewis acid catalyzed annulation reaction has been established for the synthesis of benzocyclohepta­[<i>b</i>]­indoles. This method represents a new annulation strategy to a seven-membered carbocyclic ring system from two 3-(1<i>H</i>-isochromen-1-yl)-1<i>H</i>-indole molecules using Cu­(OTf)₂ catalyst; moreover, the products, benzocyclohepta­[<i>b</i>]­indoles, can be used as the rapid mercuric ion colorimetric detection reagents