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We present a method for the synthesis of substituted indolo[1,2‐a]quinoline‐5(6H)‐ones starting from 1‐(2‐ethynylphenyl)‐1H‐indoles. The transformation involves gold‐catalyzed oxidation of the triple bond followed by acid‐promoted intramolecular cyclization at the indole C2 position. Demonstrating noteworthy versatility, the reaction tolerates a wide array of substituents on the indole core and proceeds in good to excellent yields (up to 93 %). [ABSTRACT FROM AUTHOR]

A photoredox‐promoted approach for the synthesis of [1,4]diazepino[1,7‐a]indol‐6(7H)‐ones starting from N‐indolyl phenylacrylamides and aroyl chlorides as radical source is reported. This method, that involves a cascade radical addition on C−C double bond followed by intramolecular cyclization at indole C2‐position, affords two diastereomeric indole‐fused 1,4‐diazepinones characterized by a N−C(aryl) axial chirality in yields ranging from 51 to 99%. [ABSTRACT FROM AUTHOR]

A redox umpolung strategy for the synthesis of complex tetrahydrocarbazoles is reported. The reaction involves a visible light promoted radical cation [4+2] cycloaddition between 2-vinylindoles and conjugated alkenes that proceeds with good yields and diastereoselectivity. [ABSTRACT FROM AUTHOR]

An enantioselective phosphine‐catalyzed [3+2] cycloaddition between aza‐aurones and allenoates is here described. The reaction proceeded under mild reaction conditions to afford 2‐spirocyclopentyl indolin‐3‐one derivatives as single γ‐isomer and with high levels of stereocontrol. [ABSTRACT FROM AUTHOR]

The Cover Feature shows the synthesis of substituted indolo[1,2‐a]quinoline‐5(6H)‐ones starting from 1‐(2‐ethynylphenyl)‐1H‐indoles and N‐oxides by a gold‐catalyzed oxidation of the triple bond, followed by an acid‐promoted intramolecular cyclization at the indole C‐2 position. More information can be found in the Research Article by E. Brambilla, V. Pirovano and co‐workers (DOI: 10.1002/ejoc.202400083). Cover design by Dominica Del Grosso...By Elisa Brambilla; Mariaclara Gugiatti; Silvia Rizzato; Giorgio Abbiati and Valentina PirovanoReported by Author; Author; Author; Author; Author [Extracted from the article]

The reactivity of vinyl‐/furoindole derivatives with gold‐activated π‐systems is the subject of extensive investigation. In the presence of these electrophilic partners, the realized transformations allow for the construction of different and fascinating architectures via cycloaddition and cyclization reactions often included in cascade processes. The reactions realized involving in these processes an external substituent at the indole moiety are the subject of the present minireview. [ABSTRACT FROM AUTHOR]

In this paper, we describe the use of p‐TSA based Deep Eutectic Solvents (DESs) as alternative environmental‐friendly "active" solvents for the microwave‐mediated synthesis of 6‐substituted 3,4‐fused 2‐pyranones, and in particular isocoumarins, starting from 2‐alkynyl‐(hetero)arylcarboxylates. When the alkyne terminus bears a neutral or an electron‐donating group (EDG), the reactions are fast, clean and highly regioselective, to give the 6‐endo‐dig cyclization products in good to excellent yields. For substrates bearing an electron‐withdrawing group (EWG) on the alkyne end, the regioselectivity can be tuned by adding a small amount of silver(I) triflate as co‐catalyst. DES was demonstrated to be reusable without loss of efficiency in terms of reaction yields. Based on experimental evidence and previous findings, two competitive mechanisms working simultaneously are proposed to explain the outcomes and the regioselectivity issues. An acidic Deep Eutectic Solvent is an alternative environmental‐friendly "active" media for the microwave‐mediated synthesis of 6‐substituted 3,4‐fused 2‐pyranones. [ABSTRACT FROM AUTHOR]

The review summarizes the most recent achievements in the chemistry of 2-vinylindoles and 3-vinylindoles. In particular, we focus on the behavior of these compounds as dienes in cycloaddition reactions. The majority of the literature in this field deals with [4+2] cycloaddition, and only one report of [4+1] cycloaddition has appeared in the literature until now. Thus, the main section reviews [4+2] cycloaddition with activated cyclic and acyclic dienophiles under Lewis-acid catalysis or organocatalysis conditions. In addition, cycloadditions performed with simple p-systems as dienophiles, occurring through activation by transition-metal catalysts, are reviewed. This section mainly involves the use of allenes as dienophiles under gold catalysis conditions. In both cases, the authors report excellent levels of diastereoselectivity and enantioselectivity. Two separate subsections deal with the synthesis of natural compounds and with the use of methyleneindolinones as dienophiles. [ABSTRACT FROM AUTHOR]

The gold-catalyzed synthesis of tetrahydrocarbazoles through dearomative [4+2] cycloaddition reactions of 3/2-substituted 2/3-vinylindoles with allenamides is reported. In particular, we optimized the enantioselective variant of these cycloadditions. Using allenamides as dienophiles 3-substituted 2-vinylindoles gave the corresponding carbazoles with high chemo-, regio- and enantioselectivity. Good results were obtained also with 2-methyl 3-vinylindoles even if mixtures of ( Z) and ( E) isomers were isolated in high er and in excellent overall yields. [ABSTRACT FROM AUTHOR]

This review examines sequential processes involving α,β-ynones and α,β-ynoates containing proximate nucleophiles as useful building blocks for the synthesis of heterocyclic derivatives through conjugate-addition-type, pericyclic and transition-metalcatalyzed transfer hydrogenation, hydroarylation, hydrovinylation, or hydroalkynylation reactions followed by heterocyclization. 1 Introduction 2 Conjugate Addition-Heterocyclization Processes of α,β- Ynones and α,β-Ynoates Containing Proximate Nucleophiles 2.1 Conjugate Addition-Annulation Reactions of β-(2-Aminoaryl or Heteroaryl)-α,β-Ynones 2.2 Sequential Reactions of γ-Hydroxy-α,β-Acetylenic Esters with Nucleophilic Reagents 2.3 Sequential Electrophilic Addition-Annulation Processes of α,β-Ynones Containing Proximate Nucleophiles 3 Cycloaddition-Heterocyclization Processes of α,β-Ynones and α,β-Ynoates Containing Proximate Nucleophiles 3.1 [2+2] and [4+2] Cycloaddition-Annulation Reactions 3.2 1,3-Dipolar Cycloaddition-Annulation Reactions 4 Transition-Metal-Catalyzed Addition-Heterocyclization Processes of α,β-Ynones and α,β-Ynoates Containing Proximate Nucleophiles 4.1 Palladium-Catalyzed Transfer Hydrogenation-Heterocyclization Processes 4.2 Palladium-Catalyzed Hydroarylation-Heterocyclization Processes 4.3 Rhodium-Catalyzed Hydroarylation-Heterocyclization Processes 4.4 Copper-Catalyzed Hydroarylation-Heterocyclization Processes 4.5 Transition-Metal-Catalyzed Hydrovinylation-Heterocyclization Processes 4.6 Transition-Metal-Catalyzed Hydroalkynylation-Heterocyclization Processes 5 Conclusion. [ABSTRACT FROM AUTHOR]

The gold-catalyzed intermolecular Diels-Alder cycloaddition and competitive Michael addition reactions between 2-vinylindoles and enones/enals are reported. The reaction outcome strictly correlates with the electronic character of the heteroaromatic substrate. Thus, Diels-Alder cycloadducts are the sole products in the presence of less electron-rich heterocycles, whereas Michael addition adducts are observed with more electron-rich heterocycles. Plausible competitive reaction mechanisms are proposed and discussed as well. [ABSTRACT FROM AUTHOR]

Abstract: The cycloaddition reactions of ‘all-carbon’ 1,3-diazabuta-1,3-dienes with a few conjugated and unconjugated alkynyl ketenes are described. The reactions provide some interesting azetidinones and dihydropyrimidinones bearing an alkynyl moiety. The regiochemistry of cycloadduct is related with the degree of conjugation of the alkynyl ketene. Moreover, two alternative approaches to ‘all-carbon’ 1,3-diazabuta-1,3-dienes are reported. [Copyright &y& Elsevier]

β-(2-Aminophenyl)-α,β-ynones readily react with nitrogen nucleophiles to give three major types of products, depending on reaction conditions and variation in the nucleophiles. The reaction may lead to simple 1,2-nucleophilic adducts or, at higher temperatures, to a divergent sequential cyclisation giving rise to 2-aryl-4-aminoquinolines by reaction with amines, or to substituted 2-aryl or 2-alkyl-4-alkylidene quinazolines by reaction with amidines. The latter could also be synthesised by reaction of β-(2-aminophenyl)-α,β-ynones with iminochlorides. [Copyright &y& Elsevier]

A new synthesis of quinoline derivatives was achieved by catalytic hydrogenation of 3,4-disubstituted 2-(2-formylphenyl)-isoxazolin-5(2H)-ones. In the same way, 2,3-disubstituted [1,8]naphthyridine was obtained. [Copyright &y& Elsevier]

Indole 2-carboxamide derivatives 4 underwent palladium-catalyzed intramolecular cyclization reactions to afford β-carbolinones or pyrazino [1,2-a]indoles according to different reaction pathways. The complete regioselectivity of the reactions was obtained in different reaction conditions. [ABSTRACT FROM AUTHOR]

The cycloaddition reactions of 1-p-tolyl and 1-benzyl- 2,4-diphenyl-1,3-diazabuta-1,3-dienes with a variety of aryl and alkyl isocyanate and isothiocyanate are described. The reaction mechanism is also discussed. [Copyright &y& Elsevier]

Intramolecular cyclization of 2-acyl-1-propargyl-1H-indoles in the presence of ammonia provides an easy entry to pyrazino[1,2-a]indole nucleus. [Copyright &y& Elsevier]

Studies the enantioselective synthesis of 2-amino-3-hydroxynorbornene-2-carboxylic acid derivatives using Diels-Alder reaction between cyclopentadiene and different dienophiles, operating with different Lewis acids and both with thermal and with ultrasound conditions. Control of cycloaddition reaction in favor of the exo and endo products; Catalysts used in the reactions.

Review: [115 refs. [ABSTRACT FROM AUTHOR]

Highly substituted tetrahydrocarbazole derivatives are obtained in high yields and diastereoselectivities. [ABSTRACT FROM AUTHOR]

The Lewis acid mediated diastereoselective [4 + 2]-cycloaddition of vinylindoles [e.g. (I)] and acetamidoacrylate (II) gives tetrahydrocarbazoles [e.g.(III)], which can be further derived. [ABSTRACT FROM AUTHOR]