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The organic ring closure reaction of diverse acyclic compounds is governed mostly by the Baldwin rule. The ring closure compounds shows emergent application. In recent years, ring closure reactions that are favoured by the Baldwin rules have received a lot of attention. In particular, the Baldwin rule favours the usage of sp- geometrical (diagonal) molecules in the cyclization reaction. The endo-dig cyclization help for synthesis of bulky compound in simple manner via radical coupling. The radical coupling method help for synthesis of various cyclized compounds, also heterocyclic compounds like, three – eight memebered ring compounds. Also, the endo dig cyclization used for synthesis of C-C, C-N, C-O, C-S bond forming compounds. From the all ring closing reaction, 6-endo dig cyclization has great important for synthesis of highly active 6, 7, 8 membered ring compounds. The formed 6-endo dig cyclized product has selective activity against various field cosmetics, medicinal, dye, agrochemical. There are come list of organic compounds are synthesis via 6-endo-dig cyclization like, carbazole, fused benzimidazole, fused pyrimidine, oxazole, chromenos, pyridine, quinoline etc., analogues. The 6-endo-dig cyclization reaction proceed presence of transition metal catalyst and with out catalyst. The 6-endo-dig cyclization processes can be used to synthesise a wide range of 6 membered heterocycles and carbocycles. This review compiles the significant uses of 6-endo-dig cyclization in organic synthesis from a variety of perspectives.

A silver‐catalyzed protocol for the synthesis of 3‐(1H‐isochromen)‐chromones is described. The method involves an initial 6‐endo‐dig cyclization of o‐alkynylbenzaldehydes and domino C−H alkylation and chromone annulation of the o‐hydroxyarylenaminones, which enables the installation of 1H‐isochromen and chromone in a single structure. This synthetic strategy is advantageous for the excellent regioselectivity, step economy, concise one‐pot methodology, gram‐scale synthesis, as well as high bond‐forming efficiency. [ABSTRACT FROM AUTHOR]

The manuscript describes the development of an efficient synthetic route to cinnolines, facilitating faster access to JNJ-8003 related Respiratory Syncytial Virus (RSV) non-nucleoside (NNI) inhibitors. Starting from correctly functionalized aryl halides, a Sonogashira reaction followed by S N Ar reaction with hydrazine 1,2-dicabroxylate reagents provided dihydrocinnolines directly via in situ 6-endo-dig cyclization. The dihydrocinnolines were conveniently transformed to corresponding cinnolines in one step. Notably, this three-step route to cinnolines is more practical and safer than traditional methods that involve hazardous diazo intermediates. The methodology demonstrated a broad substrate scope. Strategic selection of a readily available aryl halide enabled the synthesis of diverse cinnolines that served as JNJ-8003 analogues through late-stage functionalization. Furthermore, by capitalizing the inherent reactivity of aryl halides toward S N Ar reactions, we explored the synthesis of various heteroaromatic cinnolines. Given the extensive biological properties exhibited by cinnolines, our approach is poised to inspire further investigations in this field., (© 2025 Wiley-VCH GmbH.)

A cascade 6-endo-dig cyclization reaction was developed for the switchable synthesis of halogen and non-halogen-functionalized pyrazolo[3,4-b]pyridines from 5-aminopyrazoles and alkynyl aldehydes via C≡C bond activation with silver, iodine, or NBS. In addition to its wide substrate scope, the reaction showed good functional group tolerance as well as excellent regional selectivity. This new protocol manipulated three natural products, and the arylation, alkynylation, alkenylation, and selenization of iodine-functionalized products. These reactions demonstrated the potential applications of this new method. [ABSTRACT FROM AUTHOR]

A Cu‐catalyzed straightforward synthesis of 1‐naphthols via an 6‐endo‐dig cyclization of terminal alkynes with 2‐bromoaryl ketones in water is reported. The Cu(I) catalytic system tolerates various electron‐withdrawing and electron‐donating functional groups on both substrates and exhibits unique 6‐endo‐dig selectivity to give 1‐naphthols in moderate to good yields. [ABSTRACT FROM AUTHOR]

Here, we describe a facile approach for the synthesis of substituted 1‐naphthylamines via three‐component 6‐endo‐dig cyclization of terminal alkynes with 2‐bromoaryl ketones, primary or secondary amines in water under Pd‐free conditions. The Cu(I) catalytic system avoids a fundamental problem related to these substrates, which competitively evolve through 5‐endo‐dig cyclization pathways under metal catalysis. This unique performance unlocks a rapid access to a diverse 1‐naphthylamines library that previously required longer synthetic routes. The synthetic potential of this method was further demonstrated by the gram‐scale synthesis, and the mechanism study showed that the reaction experienced sequential halide exchange, imine‐enamine tautomerization and 6‐endo‐dig cyclization. [ABSTRACT FROM AUTHOR]

A small library of 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a Ag2CO3/TFA-catalyzed intramolecular oxacyclization of N-Boc-2-alkynylbenzimidazole substrates. In all experiments, the 6-endo-dig cyclization was exclusively achieved since the possible 5-exo-dig heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed 6-endo-dig cyclization of N-Boc-2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated. While ZnCl2 has shown limits for alkynes with an aromatic substituent, Ag2CO3/TFA demonstrated its effectiveness and compatibility regardless of the nature of the starting alkyne (aliphatic, aromatic or heteroaromatic), providing a practical regioselective access to structurally diverse 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones in good yields. Moreover, the rationalization of oxacyclization selectivity in favor of 6-endo-dig over 5-exo-dig was explained by a complementary computational study.

Enaminones show unique nucleophilic and electrophilic characteristics exhibited by the amine-alkene-carbonyl system. Gold (I) and Gold (III) complexes are exceptionally potent and superior Lewis acids having a high affinity for p bonds of alkenes, alkynes, and allenes. This review focuses on gold-catalyzed reactions of enaminones and recent advances along with their interesting mechanistic aspects. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A gold(I)‐catalyzed 6‐endo‐dig cyclization of aromatic 1,5‐enynes was developed to synthesize 2‐(naphthalen‐2‐yl)anilines. The functional group tolerance of this cyclization was examined systematically and a possible mechanism was proposed. The derivatization of 2‐(naphthalen‐2‐yl)aniline was carried out to facile access to benzo[α]carbazole, benzo[c,h]cinnoline and dibenzo[i]phenanthridine derivatives in a divergent way. [ABSTRACT FROM AUTHOR]

An efficient gold‐catalyzed synthesis of pyrazolo[1,5‐a]pyridines have been developed from pyrazolo substituted propargyl alcohols via 6‐endo‐dig cyclization. In this intramolecular cyclization reaction a new C−N bond was formed regioselectively and good to excellent yields of pyrazolo[1,5‐a]pyridines were obtained in one‐pot. [ABSTRACT FROM AUTHOR]

This review article is an attempt to highlight the most important contributions toward the synthesis of various nitrogen-containing heterocyclic compounds from corresponding propargylic ureas through regio- and chemoselective 5-exo-dig and 6-endo-dig modes of N- and O-cyclization reactions. The review is divided into three major sections. In the first section we only focus on 5-exo-dig N-cyclization fashion. In the second section 5-exo-dig O-cyclization is described. The third section is devoted to 6-endo-dig N- and O-cyclizations

An efficient and straightforward synthetic method to access substituted aminobenzophenones has been developed. This transformation was catalyzed by gold and a new C—C bond was formed through intramolecular 6-endo-dig cyclization. The substituted aminobenzophenones were obtained in good to excellent yields. [ABSTRACT FROM AUTHOR]

Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines. This review will be helpful in the development of improved methods for the synthesis of natural and biologically important compounds.

Herein we report the stereoselective total synthesis of Exserolide F. The key step involves triflic acid catalyzed highly regioselective intramolecular cyclization of an O-alkynyl benzoic acid derivative to accomplish the core isocoumarin skeleton of the natural product via 6-endo-dig mode of cyclization. The other important steps are: Sharpless asymmetric epoxidation, Barbier propargylation, Sonogashira coupling en route to access the O-alkynyl benzoic acid derivative. [ABSTRACT FROM AUTHOR]

Karrikin (KAR1), also named ‘karrikinolide’, was isolated in 2004 from smoke water and identified as a very potent germination stimulant as well as controlling early seedling development for a large variety of plant species. We reported herein an unprecedented and scalable synthesis of Karrikin (KAR1) based on an elegant and efficient 6‐endo‐dig cyclization. Moreover, we evaluated the effect of KAR1 on corn seeds germination, we carried out additional studies on the uptake of this butenolide into corn seeds, and the main soil chemiodynamic properties (i.e., persistence and mobility) were calculated or estimated. Finally, we provided a rationalization of the experimental results by building a homology model of corn KAI2, using as template the X‐ray of the KAI2 protein from Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]

[Display omitted] Treatment of 1-alkyl-4-(2-alkynylphenyl)triazoles with copper acetate resulted in the formation of mesoionic [1,2,3]triazo[5,1- a ]isoquinoliums via 6- endo -dig cyclization and C H bond oxidation. [ABSTRACT FROM AUTHOR]

Potentially bioactive angular dihydropyridocoumarin and phenanthrolinone derivatives are synthesized in good to excellent yields using readily available iron(III) chloride (FeCl3) as the catalyst. The process is very simple, straightforward and inexpensive, and provides a diverse range of pyranoquinolone or phenanthrolinone derivatives, via a 6-endo-dig mode of cyclization, starting from simple and easily available 6-(N-propargyl)aminocou-marin and -quinolone derivatives. [ABSTRACT FROM AUTHOR]

Abstract: Dipyrido[1,2-a:3′,4′-d]imidazole derivatives can be readily synthetized from various 3-alkyne-2-cyanoimidazo[1,2-a]pyridines via an efficient Grignard reagent-promoted 6-endo-dig cyclization of nitrile to alkynes. A previous optimization of the Sonogashira coupling reaction at C(3) of the 2-cyanoimidazo[1,2-a]pyridine was necessary as this coupling reaction is known to be largely influenced by the nature of the 2-substituent. [Copyright &y& Elsevier]

Background: Several natural/synthetic molecules having a structure similar to 1H-isochromen- 1-ones have been reported to display promising antioxidants and platelet aggregation inhibitory activity. Isocoumarin (1H-2-benzopyran-1-one) skeleton, either whole or as a part of the molecular framework, has been explored for its antioxidant or antiplatelet activities., Introduction: Based on the literature, a new prototype, i.e., 3-phenyl-1H-isochromen-1-ones based compounds, has been rationalized to possess both antioxidant as well as antiplatelet activities. Consequently, no reports are available regarding its inhibition either by cyclooxygenase-1 (COX-1) enzyme or by arachidonic acid (AA)-induced platelet aggregation. This prompted us to investigate 3-phenyl-1H-isochromen-1-ones towards antioxidant and antiplatelet agents., Methods: The goal of this work was to identify new 3-phenyl-1H-isochromen-1-ones based compounds via synthesis of a series of analogues, followed by performing in vitro antioxidant as well as AA-induced antiplatelet activities. Then, identification of potent compounds by SAR and molecular docking studies was carried out., Results: Out of all synthesized 3-phenyl-1H-isochromen-1-ones analogues, five compounds showed 7-fold to 16-fold more highly potent antioxidant activities than ascorbic acid. Altogether, ten 3-phenyl-1H-isochromen- 1-one analogues displayed antioxidant activities in 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Almost all the 3-phenyl-1H-isochromen-1-one analogues exhibited potent AA-induced antiplatelet activity; few of them displayed 7-folds more activity as compared to aspirin. Further, in silico analysis validated the wet results., Conclusion: We disclose the first detailed study for the identification of 3-phenyl-1H-isochromen-1-one analogues as highly potent antioxidant as well as antiplatelet agents. The article describes the scaffold designing, synthesis, bioevaluation, structure-activity relationship, and in silico studies of a pharmaceutically privileged bioactive 3-phenyl-1H-isochromen-1-one class of heterocycles., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

• [1,2,3]triazolo[5,1– a ]isoquinolines have been synthesized. • A three-component cascade reaction has been developed. • [1,2,3]triazolo[5,1– a ]isoquinolines have been converted to other molecules. Novel AlCl 3 -promoted, three component cascade Henry reaction-triazole formation-intramolecular 6- endo -dig cyclization reactions between 2-alkynylaryl aldehydes, nitroalkanes, and sodium azide for the assembly of [1,2,3]triazolo[5,1- a ]isoquinolines have been developed. Further transformations of representative [1,2,3]triazolo[5,1- a ]isoquinolines are also described. [ABSTRACT FROM AUTHOR]