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Diarylacetylenes undergo anti -dimagnesiation using magnesium bromide and sodium dispersion to afford (E)-1,2-dimagnesioalkenes. This dimagnesiation utilizes simple magnesium bromide as a reduction-resistant electrophile, contrasting with the previously reported dimagnesiation using tricky organomagnesium halides. The resulting vicinal double Grignard reagents react with various electrophiles to yield multisubstituted alkenes stereoselectively. [ABSTRACT FROM AUTHOR]

Functionalized 1,2,4,5-tetrasubstituted benzenes are synthetically difficult or laborious to access. The Rh-catalyzed [2+2+2] cycloaddition of a diyne and internal alkyne offers a seemingly straightforward route to these scaffolds; however, this has been largely restricted to alkynes bearing activating (coordinating) functional groups, with very few examples of unactivated alkynes. In this work, we disclose an assessment of Rh-catalyzed [2+2+2] cycloadditions employing unactivated internal alkynes, focusing on the structural diversity and compatibility of both alkyne and diyne components. The limitations of this method are disclosed, with exceptionally bulky alkynes and specific functional groups undergoing side reactions. Furthermore, the practicalities of gram-scale reactions and catalyst recovery/reuse are demonstrated. [ABSTRACT FROM AUTHOR]

An efficient methodology for the synthesis of highly diverse 4-aminoquinoline derivatives from activated alkynes and 2-aminobenzonitriles mediated by Lewis acid is described. The reaction proceeds via sequential aza-Michael addition/intramolecular annulation to afford highly substituted 4-aminoquinolines in good yields. The reaction is operationally simple and has high atom-economy with broad substrate scope. The post synthetic application of the reaction provides 4 H -benzo[ de ][1,6]naphthyridines. [ABSTRACT FROM AUTHOR]

A silver-catalyzed dearomative decarboxylative [3+2] spiroannulation of aryl oxamic acids with alkynes is described. The reaction provides reliable access to a range of azaspiro[4,5]trienones in moderate yields in aqueous media. In addition, the reaction exhibits a broad substrate scope and good functional group compatibility. [ABSTRACT FROM AUTHOR]

Reductive functionalization of C–C unsaturated systems, including alkenes and alkynes, with a range of hydroelements (H[E]) is one of the most fundamental and highly practical methods for the synthesis of functionalized hydrocarbons. Since the resultant hydrocarbon products have strong applicability as synthetic intermediates, numerous homogeneous organo(metallic) catalysts have been intensively utilized to date for reductive functionalization reactions. In particular, well-defined transition-metal-based catalysts capable of controlling the regio- or stereoselectivity of a product by harnessing the addition of H[E] (E = H, B, Si, Ge) into Cα –Cβ unsaturated bonds have drawn special attention. In this review , we describe recent examples of transition-metal catalytic systems (M = Fe, Co, Rh, Pd, Ni) for regio- or stereodivergent hydroelementation reactions of (conjugated) alkenes, alkynes, and allenes to give a pair of isomeric products in high selectivities from the same starting compounds simply by variation of the ligand. Mechanistic aspects of the ligand-controlled selectivity divergence are discussed in detail on the basis of experimental observations and/or computational insights. 1 Introduction 2 Hydroelementation of Alkenes and Alkynes 3 Hydroelementation of Conjugated Dienes and Diynes 4 Hydroelementation of Allenes 5 Summary and Outlook [ABSTRACT FROM AUTHOR]

Unstable tetra(methoxycarbonyl)cyclopentadienone was investigated in the synthesis of electron-deficient cycloheptatrienes via [4+2]-cycloaddition/cycloelimination reaction with cyclopropenes. The use of its stable dimer did not afford the product although similar reactions with alkynes have been reported. Quantum chemical calculation revealed that cyclopentadienone is not generated from the dimer and the reaction with alkynes proceeds via a more complicated cycloelimination/cycloaddition/cycloelimination cascade. However, the formation of cycloheptatrienes was found favorable over the formation of the dimer. Therefore, the trapping of tetra(methoxycarbonyl)cyclopentadienone upon formation was successful to give cycloheptatrienes with five ester groups. The use of methyl coumalate as a four-electron component was successful with cyclopropenes containing only one ester group to afford only two ester groups in the product. [ABSTRACT FROM AUTHOR]

The development of new catalytic methods based on lower-cost metals under environmentally friendly conditions is still a challenge. Herein, we report an efficient strategy for the synthesis of vinyl sulfones from O -propargyl alkynes and sodium salts of sulfinic acids using silver nitrate, an inexpensive and readily available catalyst, under air atmosphere using aqueous conditions. The products were obtained in good to moderate yields, and the mechanism of the reaction was also investigated. [ABSTRACT FROM AUTHOR]

A new method for the intramolecular electrophilic ipso -cyclization of alkynes with triflic anhydride-activated sulfoxides, followed by demethylation with triethylamine in one pot, is described for the synthesis of 3-thiospiro[4.5]-decatrienones in moderate to good yields. This method provides a facile strategy for assembling the sulfur-substituted spirocyclic compounds. [ABSTRACT FROM AUTHOR]

The atroposelective transformation of alkynes is an efficient protocol for the assembly of axially chiral compounds. Benefitting from the rapid development of chiral organocatalysts, the organocatalytic atroposelective reactions of alkynes have been extensively studied over the past decades. An array of chiral catalysts, including chiral Brønsted acid catalysts, secondary amine catalysts, N -heterocyclic carbene (NHC) catalysts, thiourea catalysts and N -squaramide catalysts, are employed in enantioselective reactions of different alkynes. This short review summarizes the recent advances on organocatalytic atroposelective reactions of alkynes according to the type of alkyne substrate. The reaction mechanisms, modes of enantiocontrol, product diversity and applications are highlighted. 1 Introduction 2 Electron-Rich Aryl Alkynes 3 Electron-Deficient Aryl Alkynes 4 Other Types of Alkynes 5 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

An iridium-catalyzed ligand-controlled semi-reduction of alkynes employing H2 O as the hydrogen donor, together with its application, is reported. The use of di- tert -butylphosphinous chloride is crucial for stereoselectivity toward Z -olefins, whereas the use of 2-(diphenylphosphino)benzaldehyde is crucial for stereoselectivity toward E -olefins. More than 35 alkenes were obtained in good yields and high stereoselectivities. The utility of the current method in practical applications was investigated by studying the drug effects of (E)-1,3-dimethoxy-5-styrylbenzene on nerve growth in a zebrafish model. [ABSTRACT FROM AUTHOR]

This article discusses the development of a heterogeneous copper-based catalyst, Cu3N NC, for the protosilylation of unsaturated compounds. The catalyst was found to be effective in the synthesis of various silanes from alkynes, alkenes, and imines under base- and ligand-free conditions. The Cu3N NC catalyst demonstrated high activity and durability, and it could be reused multiple times without significant loss of activity. The article also presents the protosilylation of alkynes with electron-withdrawing groups, the protosilylation of alkenes, and the protosilylation of imines using the Cu3N NC catalyst. The findings contribute to the development of sustainable technologies for the production of valuable silanes. [Extracted from the article]

This article discusses the development of a nickel-catalyzed hydroalkynylation reaction of 1,3-dienes with simple alkynes. The researchers used a Xantphos ligand to achieve regioselective hydroalkynylation, producing a variety of allylic alkyne products. They optimized the reaction conditions by adding water, which increased the yield of the desired product. The method demonstrated excellent functional-group tolerance and a wide substrate scope for alkynes. The researchers also proposed a mechanism for the reaction based on previous studies. Further research will focus on asymmetric variants, expanding the reaction scope, and exploring synthetic applications. [Extracted from the article]

This article discusses the synthesis of fluorinated molecules, which are important in drug discovery and crop science. The authors focus on the regiodivergent borylation of fluorinated alkynes using copper catalysis. They describe the optimization of reaction conditions and the scope and limitations of the borylation reactions. The authors also developed a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction to selectively functionalize the borylated olefins. The article provides a proposed mechanism for the reactions and discusses the scalability of the reactions. [Extracted from the article]

This article discusses the synthesis and characterization of various 1-thiaphenalene derivatives using a radical approach and photoredox catalysis. The reaction involves the intermolecular cyclization of 1-naphthalenesulfonyl chlorides and alkynes under mild conditions, resulting in high product diversity and broad functional-group tolerance. The authors provide a plausible reaction mechanism and experimental details for the synthesis of specific compounds, which were characterized using techniques such as NMR, HRMS, and IR spectroscopy. This information can be valuable for researchers studying these compounds or related topics. [Extracted from the article]

This article explores the use of alumina as an activator for copper catalysts in the hydroboration of alkynes. Hydroboration of alkynes is important in the synthesis of vinylboronic acids and esters. The traditional method using dialkoxyboranes has limitations, so transition-metal-catalyzed hydroborations have gained popularity. Alumina simplifies the experimental procedure and allows for hydroboration in air and aqueous media. The article presents the results of different reaction conditions and demonstrates successful hydroboration of various substrates. It also discusses the use of alumina as a base surrogate in Cu-catalyzed hydroboration and provides technical information and procedures for synthesis and characterization of compounds. [Extracted from the article]

This article provides an overview of recent advancements in transition-metal-catalyzed Sonogashira cross-coupling reactions of alkyl electrophiles. It discusses the challenges associated with coupling nonactivated alkyl electrophiles and highlights three catalytic systems that have been developed to address these challenges. The article also mentions the development of enantioselective Sonogashira reactions using copper catalysts with chiral ligands. The challenges and future directions in this field are also discussed. [Extracted from the article]

This article discusses the synthesis of ynamides, a class of N-alkynyl compounds, through various catalytic reactions. The authors highlight the importance of ynamides in the synthesis of nitrogen-containing scaffolds and summarize existing methods for their synthesis. They also present their own research on the direct catalytic addition of terminal alkynes to azodicarboxylates to produce ynehydrazides, which can then be converted into ynamides. The authors propose potential future directions for further research in this field. [Extracted from the article]

This article explores the borylative difunctionalization of unsaturated hydrocarbons using borylcopper species. It discusses the importance of developing simple and effective methods for preparing organoboron compounds. The article focuses on Cu-catalyzed reactions, including regioselective hydroborations, boroallylation, boroacylation, and boroformylation of 1,2-dienes. The authors describe the development of catalyst systems and ligands that have shown high yields and selectivities in these reactions. The research aims to contribute to the field of organic synthesis by developing efficient and selective catalytic reactions for the functionalization of unsaturated hydrocarbons. [Extracted from the article]

This document provides information on the synthesis and characterization of various compounds belonging to the imidazo[2,1-b][1,3]thiazine family. The compounds were synthesized using a specific method and characterized using various techniques such as NMR and HRMS. The document includes details on the physical properties, yields, and spectral data of each compound. The document also acknowledges the contribution of M. Malikėnas for HRMS measurements and provides a link to supporting information. [Extracted from the article]

This article provides an overview of the palladium-catalyzed homo-dimerization of terminal alkynes, a process used in synthetic chemistry. It discusses different methods and catalysts that have been developed to achieve selective dimerization of alkynes. The use of palladium catalysts has shown significant advancements, and the article also explores environmentally friendly approaches using water as a solvent and mechanochemical conditions. The text emphasizes the potential for practical and industrial applications, but further research is needed in this field. [Extracted from the article]

The given text provides information on the synthesis and characterization of various indole compounds. The compounds described include derivatives of indole with different substituents, such as chlorine, bromine, nitro, trifluoromethyl, and carboxylate groups. The document includes data such as melting points, NMR spectra, and mass spectrometry results for each compound. These compounds may have potential applications in various fields, such as pharmaceuticals or materials science. [Extracted from the article]

This document provides information on the synthesis and characterization of several compounds, including 2,3,4,5-tetraphenyl-N-(p-tolyl)-1H-benzo[b]azepine-9-carboxamidecarboxamide (8b), N-(4-chlorophenyl)-2,3,4,5-tetraphenyl-1H-benzo[b]azepine-9-carboxamide (8d), and N-(3-methoxyphenyl)-2,3,4,5-tetraphenyl-1H-benzo[b]azepine-9-carboxamide (8e). The compounds were synthesized using a general procedure and purified using PTLC. The physical and spectroscopic properties of the compounds were determined, including melting point, Rf value, IR, 1H NMR, 13C NMR, and HRMS. The computational methodology used for the study is also mentioned, along with acknowledgments and supporting information. [Extracted from the article]

(E)- N -(2-Cyclohexyl-1-phenyl-3-(trimethylsilyl)allyl)aniline (19) General procedure A was used to react I N i -benzylaniline (183 mg, 1.0 mmol) with (cyclohexylethynyl)trimethylsilane (180 mg, 1.0 mmol) in the presence of catalyst B II-Bu b (111 mg, 0.1 mmol) for 24 h at 140 °C. Keywords: alkynes; allylamines; C-H activation; hydroaminoalkyl-ation; titanium; catalysis EN alkynes allylamines C-H activation hydroaminoalkyl-ation titanium catalysis 3759 3776 18 11/01/23 20231116 NES 231116 Graph The catalytic hydroaminoalkylation of alkenes [1][8] (Scheme 1), which takes place by a 100% atom-economical addition of the -C-H bond of a primary, [8] secondary, [8][8][8][8] or tertiary [8][8] amine across the alkene double bond, has received considerable attention over the past 15 years. N -(3,3-Dimethyl-2-methylenebutyl)aniline (1) 4d General procedure A was used to react I N i -methylaniline (107 mg, 1.0 mmol) with I tert i -butylacetylene (99 mg, 1.2 mmol) in the presence of catalyst B II-DIPP b (194 mg, 0.1 mmol) for 24 h at 140 °C. 3-Chloro- N -(3,3-dimethyl-2-methylenebutyl)aniline (5) General procedure A was used to react 3-chloro- I N i -methylaniline (142 mg, 1.0 mmol) with I tert i -butylacetylene (99 mg, 1.2 mmol) in the presence of catalyst B II-DIPP b (194 mg, 0.1 mmol) for 24 h at 140 °C. N -(3,3-Dimethyl-2-methylenebutyl)-4-(trifluoromethoxy)aniline (7) General procedure A was used to react I N i -methyl-4-(trifluoromethoxy)aniline (191 mg, 1.0 mmol) with I tert i -butylacetylene (99 mg, 1.2 mmol) in the presence of catalyst B II-DIPP b (194 mg, 0.1 mmol) for 24 h at 140 °C. [Extracted from the article]

Keywords: heterocycles; alkynes; cyclization; gold catalysis; norbornene EN heterocycles alkynes cyclization gold catalysis norbornene 3652 3661 10 10/19/23 20231102 NES 231102 Graph Direct C-H functionalization of heteroarenes has advanced significantly in recent decades, allowing access to a wide range of heteroarenes for the development of new pharmaceuticals and functional materials. Purification by flash column chromatography (silica gel, hexanes/EtOAc 200:1) provided B 1c b ; yield: 226 mg (63%); yellow solid; mp 110-112 °C. Purification by flash column chromatography (silica gel, hexanes/EtOAc 200:1) provided B 1e b ; yield: 451 mg (70%); orange liquid. Purification by flash column chromatography (silica gel, hexanes/EtOAc 100:1) provided B 1o b ; yield: 241 mg (95%); yellow liquid. [Extracted from the article]

Keywords: annulation; C-H functionalization; fused heterocycles; rhodium catalysis; thienopyrrole EN annulation C-H functionalization fused heterocycles rhodium catalysis thienopyrrole 3582 3588 7 10/19/23 20231102 NES 231102 Graph Fused heterocyclic compounds have attracted much attention in a wide range of fields including pharmaceuticals, agrichemicals, and organic materials, due to their unique bioactivities as well as electronic and optical properties. Thus, they recently reported that I N i -(pivaloyloxy)thiophene-3-carboxamide undergoes formal Lossen rearrangement/oxidative [3+2] annulation with bulky internal alkynes under Cp SP A sp Rh(III) catalysis to form thieno[3,2- I b i ]pyrrole derivatives. The Cp*Rh(I) species liberated at the last step is reoxidized by a silver salt oxidant to regenerate the active Cp*Rh(III) species. Besides these 3-(acetylamino)thiophenes, 2-(acetylamino)thiophene ( B 1f b ) could also be employed for the present annulation to construct a thieno[2,3- I b i ]pyrrole core, although the yield of product B 3fa b was low. [Extracted from the article]

Keywords: ruthenium catalysis; mandelic acids; alkynes; annulation; isocoumarins EN ruthenium catalysis mandelic acids alkynes annulation isocoumarins 2005 2010 6 10/09/23 20231024 NES 231024 Graph Isocoumarins are an important class of natural lactones, and their skeletal structure is an important part of many active pharmaceutical ingredients. At present, the major methods for synthesizing isocoumarins include (1) the cyclization reaction of I ortho i -halogen-substituted benzoic acids or their esters or amides with 1,3-diketones or internal alkynes; [10][11][12] and (2) the internal cyclization reaction of I ortho i -alkenyl- or alkynyl-substituted benzoic acids or their esters. The reactions of benzaldehydes B 5 b and benzoic acids B 6 b with B 2a b proceeded when the amount of Cu(OAc) SB 2 sb -H SB 2 sb O was increased to 1.5 equivalents and the reaction time was shortened to ten hours. Ruthenium(II)-Catalyzed C-H Annulation of Mandelic Acids with Internal Alkynes to Construct Isocoumarins. [Extracted from the article]

SP 1 sp H NMR (600 MHz, CDCl SB 3 sb ): = 7.94 (dd, I J i = 5.4, 3.1 Hz, 2 H), 7.79 (dd, I J i = 5.5, 3.1 Hz, 2 H), 6.87 (dd, I J i = 2.8, 2.0 Hz, 1 H), 6.26 (t, I J i = 3.5 Hz, 1 H), 6.23 (dd, I J i = 3.7, 1.8 Hz, 1 H), 4.54 (d, I J i = 2.6 Hz, 2 H), 2.27 (t, I J i = 2.6 Hz, 1 H). Pyrroles 5 by Sonogashira Coupling; General Procedure 8 A stirred mixture of CuI (17 mg, 0.09 mmol), PPh SB 3 sb (90 mg, 0.34 mmol), and Pd(OAc) SB 2 sb (17 mg, 0.08 mmol) was purged with N SB 2 sb and heated to 50 °C. 2-[(1-Prop-2-yn-1-yl-1 H -pyrrol-2-yl)carbamoyl]benzyl Acetate (9) Ac SB 2 sb O (0.5 mL) and Et SB 3 sb N (1 mL) were added to a stirred solution of B 8g b (250 mg, 0.98 mmol) in CH SB 2 sb Cl SB 2 sb (15 mL). SP 1 sp H NMR (400 MHz, CDCl SB 3 sb ): = 7.95 (dd, I J i = 5.5, 3.0 Hz, 2 H, AA'BB'), 7.80 (dd, I J i = 5.5, 3.0 Hz, 2 H, AA'BB'), 7.20 (dd, I J i = 5.1, 0.9 Hz, 1 H), 7.01-6.99 (m, 1 H), 6.92 (dd, I J i = 4.9, 2.5 Hz, 1 H), 6.89 (dd, I J i = 5.4, 1.8 Hz, 1 H), 6.30 (dd, I J i = 4.9, 3.1 Hz, 2 H), 4.82 (d, I J i = 5.8 Hz, 2 H). [Extracted from the article]

SP 1 sp H NMR (600 MHz, CDCl SB 3 sb ): = 7.94 (dd, I J i = 5.4, 3.1 Hz, 2 H), 7.79 (dd, I J i = 5.5, 3.1 Hz, 2 H), 6.87 (dd, I J i = 2.8, 2.0 Hz, 1 H), 6.26 (t, I J i = 3.5 Hz, 1 H), 6.23 (dd, I J i = 3.7, 1.8 Hz, 1 H), 4.54 (d, I J i = 2.6 Hz, 2 H), 2.27 (t, I J i = 2.6 Hz, 1 H). Pyrroles 5 by Sonogashira Coupling; General Procedure 8 A stirred mixture of CuI (17 mg, 0.09 mmol), PPh SB 3 sb (90 mg, 0.34 mmol), and Pd(OAc) SB 2 sb (17 mg, 0.08 mmol) was purged with N SB 2 sb and heated to 50 °C. 2-[(1-Prop-2-yn-1-yl-1 H -pyrrol-2-yl)carbamoyl]benzyl Acetate (9) Ac SB 2 sb O (0.5 mL) and Et SB 3 sb N (1 mL) were added to a stirred solution of B 8g b (250 mg, 0.98 mmol) in CH SB 2 sb Cl SB 2 sb (15 mL). SP 1 sp H NMR (400 MHz, CDCl SB 3 sb ): = 7.95 (dd, I J i = 5.5, 3.0 Hz, 2 H, AA'BB'), 7.80 (dd, I J i = 5.5, 3.0 Hz, 2 H, AA'BB'), 7.20 (dd, I J i = 5.1, 0.9 Hz, 1 H), 7.01-6.99 (m, 1 H), 6.92 (dd, I J i = 4.9, 2.5 Hz, 1 H), 6.89 (dd, I J i = 5.4, 1.8 Hz, 1 H), 6.30 (dd, I J i = 4.9, 3.1 Hz, 2 H), 4.82 (d, I J i = 5.8 Hz, 2 H). [Extracted from the article]

Keywords: cross-coupling; copper; catalysis; heterocycles; alkynes EN cross-coupling copper catalysis heterocycles alkynes 2370 2376 7 07/14/23 20230801 NES 230801 Graph The FDA has approved 37 new drugs and combination therapies in 2022. [13][14][15] Metalloamination/cyclization promoted by diethylzinc proceeded optimally at 90 °C when benzotrifluoride (BTF) was used as the reaction solvent, although toluene and even 1,2-DME can be substituted. The J. Young tube was placed in a 90 °C oil bath and the cyclization reaction was monitored by NMR (indicated by the recession of the alkene peaks), using BTF as an internal standard. [Extracted from the article]

Alkynes, isoquinolines, axial chirality, C-H functionalization, iridium catalysis, asymmetric synthesis Then, isoquinoline 1 (0.2 mmol), alkyne 2 (0.2 mmol), and NaBAr F (35.4 mg, 0.04 mmol, 20 mol%) were added under argon and the tube was heated at 80 °C for 10-24 h. Keywords: alkynes; isoquinolines; axial chirality; C-H functionalization; iridium catalysis; asymmetric synthesis EN alkynes isoquinolines axial chirality C-H functionalization iridium catalysis asymmetric synthesis 1442 1446 5 07/11/23 20230725 NES 230725 Graph Transition-metal-catalyzed enantioselective C-H functionalization represents one of the most valuable and straightforward routes to optically active molecules by direct transformations of C-H compounds. [Extracted from the article]

Keywords: chiral phosphoric acid; organocatalysis; cycloaddition; alkenes; alkynes EN chiral phosphoric acid organocatalysis cycloaddition alkenes alkynes 1200 1214 15 06/19/23 20230704 NES 230704 1 Introduction Asymmetric cycloaddition reaction is the most powerful strategy for the construction of various enantioenriched carbocycles and heterocycles, [1] because it provides an efficient and completely atom-economical route from simple precursors. In order to achieve this goal, we needed to overcome the following issues: (1) realization of efficient cycloaddition of alkynes with appropriate partners; (2) the installation of suitable groups onto alkynes to avoid free rotation around the potential C-C axes; (3) the choice of a competent chiral catalyst to promote the designed cycloaddition reactions and to control the stereoselectivity. 3 CPA-Catalyzed Cycloaddition of Alkynes Although the CPA-catalyzed cycloaddition of alkenes have been well documented, the CPA-catalyzed asymmetric cycloaddition reaction of alkynes is still lacking. On the other hand, the cycloaddition of alkynylnaphthols with imines proceeded via a sequential [4+2] cycloaddition, an alkyne-type Povarov cycloaddition, and an auto-oxidation reaction. [Extracted from the article]

After synthesizing alkyne hydrazones B 5a b through a simple condensation of I p i -toluenesulfonylhydrazide with the alkyne hydrazones, the resulting compounds can react with NIS to synthesize B 7a b I via i a chemoselective pathway; compound B 7a b can be easily hydrolyzed, leading to alkyne hydrazides B 6a b . Keywords: tandem reactions; N -iodosuccinimide; lactones; tosylhydrazones; alkynes; oxidation EN tandem reactions N -iodosuccinimide lactones tosylhydrazones alkynes oxidation 1270 1274 5 06/19/23 20230704 NES 230704 Tandem C-C and C-X bond formations are among the most powerful approaches for the construction of a broad spectrum of structurally complex molecules from readily available starting materials in a convergent way. In the case of B 3a b synthesis, the 5- I exo i -dig cyclization is preferred over the 6- I endo i -dig cyclization; however, in the case of B 2a b synthesis, the 6- I endo i -dig cyclization is the main pathway for the cyclization step. Owing to the significance of pyranoquinoline and isobenzofuran moieties, which are known to be present in a variety of alkaloids and possess a wide range of pharmacological and biological activities, [6] we report herein the tandem oxidation-ring closure reactions of alkyne hydrazones to afford fused lactones by using NIS in the presence of water. [Extracted from the article]

Direct functionalization of alkynes under oxidative conditions is challenging, as alkynes are usually recalcitrant towards typical oxidants. Herein, we communicate a strategy for the divergent functionalization of alkynes with photoexcited acridinium organic dyes, presumably via the formation of vinyl cation radicals as key intermediates. Based on the nature of the nucleophiles, different types of difunctionalized products were obtained in moderate to good yields. Addition of lithium Lewis acids resulted in a surprising reversal of diastereocontrol. [ABSTRACT FROM AUTHOR]

Cobalt-catalyzed hydroalkynylation of alkynes, alkenes, and imines affords internal alkynes with various functional groups adjacent to the carbon–carbon triple bond moiety in an atom-economical manner. In addition, cross-coupling of in situ generated alkynylcobalt species from terminal alkynes, haloalkynes, and metal acetylides with (hetero)aromatic compounds and organic halides selectively provides various internal aryl- and alkylalkynes. 1 Introduction 2 Hydroalkynylation of Alkynes for 1,3-Enyne Synthesis 3 Hydroalkynylation of Polar and Nonpolar Double Bonds 4 Dehydrogenative Cross-Coupling Reaction Using Terminal Alkynes with Aromatic Compounds 5 Cross-Coupling Reactions Using Haloalkynes as the Coupling Partners 6 Cross-Coupling Reactions Using Metal Acetylides 7 Conclusion [ABSTRACT FROM AUTHOR]

The radical bromoallylation of alkynes, allenes, and vinylidene cyclopropanes proceeds efficiently in the presence of a radical initiator to give 2-bromo-substituted 1,4-, 1,5-, and 1,6-diene derivatives, respectively. Three-component reactions comprised of allenes, electron-deficient alkenes, and allyl bromides give 1,7-dienes in good yields. The bromoallylation of an arylalkene can override β-scission of the bromine radical from β-bromoalkyl radicals to give 5-bromoalkenes, whilst the bromoallylation of vinylcyclopropanes is accompanied by 5- exo ring closure to give 1-(bromomethyl)-2-vinylcyclopentane derivatives in good yields. All of the products contain a reactive vinyl bromide moiety, which can be readily functionalized by Pd-catalyzed cross-coupling and radical cascade reactions. 1 Introduction 2 Synthesis of 1,4-Dienes by Bromoallylation of Acetylenes 3 Synthesis of 1,5-Dienes by Bromoallylation of Allenes 4 Synthesis of 1,6-Dienes by Bromoallylation of Methylenecyclopropanes 5 Synthesis of 1,7-Dienes by Bromoallylation of Allenes and Electron-Deficient Alkenes 6 Bromoallylation of Arylalkenes and Vinylcyclopropanes 7 Conclusion [ABSTRACT FROM AUTHOR]

1 H -Isochromenes and 1,2-dihydroisoquinolines are synthesized by regioselective indium(III)-catalyzed intramolecular hydrofunctionalization of o -(alkynyl)benzyl derivatives. The reaction with o -(alkynyl)benzyl alcohols and amines proceeds using indium triiodide (5–10 mol%) in toluene at 80–100 °C via regioselective 6- endo - dig intramolecular alkyne hydroalkoxylation or hydroamination in good yields. Alternatively, the cycloisomerization reaction of o -(alkynyl)benzaldehydes and imine derivatives using InI3 (5 mol%) and the Hantzsch ester (120 mol%) takes place, under milder reaction conditions, to give a variety of functionalized 1 H -isochromenes and 1,2-dihydroisoquinolines through a domino cycloisomerization/reduction approach. [ABSTRACT FROM AUTHOR]

A novel approach for the stereoselective construction of N–N atropisomeric compounds by a Pd-catalyzed 5- endo -hydroaminocyclization is described herein. A broad range of bisheterocycles , connected by a configurationally stable N–N stereogenic axis, were prepared with catalyst control in enantioenriched form. [ABSTRACT FROM AUTHOR]

Stereoselective construction of conjugated dienes and polyenes has remained an enduring synthetic problem owing to the central roles these compounds play in natural product synthesis, methodology, and medicine. This review focuses on recent developments in dienylation as an emerging strategy for the direct installation of unsaturated four-carbon units of conjugated π-systems, outlining the regio- and stereoselectivity, as well as the synthetic scope of reactions with various dienylating reagents and the mechanistic implications of the catalytic cross-coupling processes that are used to enable dienylation. 1 Introduction 2 Sulfolenes 3 1,3-Dienes 4 Small-Ring Dienylation Reagents 5 Pyrones, Alkynes, and Homoallenylboronates 6 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

An extremely simple method is developed to prepare 4,5-benzotropones and 2,3,4,5-dibenzotropones via one-pot cycloaddition reactions of alkynes with naphthoquinones and dibenzoquinones mediated by BF3 ·Et2 O. Various mono- and disubstituted phenylacetylenes, multisubstituted 1,2-naphthoquinones and dibenzoquinone substrates are investigated. In addition, a scale-up synthesis of 7-phenyl-5 H -dibenzo[ a , c ][7]annulen-5-one and further derivation of 7-(4-fluorophenyl)-5 H -dibenzo[ a , c ][7]annulen-5-one are explored. [ABSTRACT FROM AUTHOR]

Using (PPh3)2 CuBH4 as catalyst, a convenient, efficient, and inexpensive palladium-free catalytic system has been developed to catalyze Sonogashira cross-coupling of o -iodoanilines with terminal alkynes under an air atmosphere to give a range of 2-ethynylaniline derivatives with up to 99% yield. This protocol is amenable to scale up. Notable features of the approach include good functional group tolerance, air atmosphere, and excellent yields. [ABSTRACT FROM AUTHOR]

Cycloadditions of nitrones with alkynes usually occur best under heat activation. Due to the instability of the formed isoxazolines, alternative activation methods must be found. Here, hyperbaric conditions are used to transform nitrones generated from unprotected carbohydrates into the corresponding polyhydroxy-isoxazolines at room temperature. The reaction proved completely regioselective in favor of the 5-substituted 4-isoxazolines, and the products are obtained in good yields as mixtures of the two possible diastereoisomers. Further transformations into biologically valuable targets are described. The whole synthesis constitutes a very straightforward procedure for the transformation of aldoses, and is highly compatible with the principles of green chemistry. [ABSTRACT FROM AUTHOR]

Here, we report a RhI3-catalyzed intramolecular carboamination reaction to access polysubstituted indoles. The protocol features a broad substrate scope (>20 examples), good functional-group compatibility, and a low catalyst loading (5 mol% Rh). Good to excellent yields (up to 98%) were obtained. An unprecedented C–N bond-cleavage mode via a six-membered transition state σ-bond metathesis mechanism was proposed based on control experiments. A series of C3-allylated indole derivatives were accessed, proving that the system provides an alternative catalytic route to polysubstituted indoles. [ABSTRACT FROM AUTHOR]

This account relates briefly the personal trajectory of the author and the thought processes that went into solving synthetic problems and developing new reactions more generally useful in organic synthesis. 1 Preamble and Early Education 2 In France with Sir Derek Barton 3 Chemistry at Ecole Polytechnique and at the ICSN 4 Final Remarks [ABSTRACT FROM AUTHOR]

Halodiazirines have emerged as very useful reagents in photochemically or thermally mediated cyclopropanation reactions with alkenes. This short review highlights the synthetic applications of these reagents as precursors of halocarbenes in transformations with various alkenes. 1 Introduction 2 Cyclopropanation of Aryl Halodiazirines 3 Tandem Reactions Using Aryl Halodiazirines 4 Cyclopropanation of Alkyl- and Benzyl-halodiazirines 5 Cyclopropanation of Other Halodiazirines 6 Reactions of Halodiazirines with Alkynes 7 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

This review focuses on the carbocyclization reactions of alkyne-containing substrates catalyzed by Brønsted acids. The electrophilic activation occurs either by direct protonation of the alkyne or by formation of an intermediate cation that further reacts with the alkyne to give a key vinyl cation intermediate. Specific focus is placed on the selectivity of the various methodologies described herein and on mechanistic rationales. 1 Introduction 2 Brønsted Acid Catalyzed Alkyne Carbocyclization Involving C(sp) Reaction Partners 2.1 Brønsted Acid Catalyzed Cyclization of Diynes 2.2 Brønsted Acid Catalyzed Cyclization of Allenynes 3 Brønsted Acid Catalyzed Alkyne Carbocyclization Involving C(sp2) Reaction Partners 3.1 Brønsted Acid Catalyzed Cycloisomerization of Enynes 3.1.1 Initial Protonation of the Alkene Function 3.1.2 Initial Protonation of the Alkyne Function 3.1.3 A Conia-Ene Reaction 3.2 Electrophile-Induced Carbocyclization Involving Other C(sp2)-Based Reaction Partners 3.2.1 Iminium Electrophiles 3.2.2 Oxonium Electrophiles 3.2.3 Isocyanate and Thioisocyanate Electrophiles 3.3 Brønsted Acid Catalyzed Cycloisomerization of Aryl-alkynes 3.3.1 Reactions Using Excess or Stoichiometric Amounts of Brønsted Acid 3.3.2 Reactions Using Substoichiometric Amounts of Brønsted Acid 3.3.3 Heteroatom-Substituted Alkynes 3.3.4 Enantioselective Brønsted Acid Catalyzed Cycloisomerization of Aryl-alkynes 4 Brønsted Acid Catalyzed Alkyne Carbocyclization Involving C(sp3) Reaction Partners: Alkyne-alkane Cycloisomerization 5 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

An efficient protocol has been developed for the synthesis of larger condensed arenes from aromatic hydrocarbons and internal alkynes. This protocol uses readily available [CpRhI2 ]n as a catalyst and Cu(OAc)2 as an oxidant and proceeds smoothly through undirected double C–H activation. The addition of trifluoroacetic acid has a crucial positive impact on the reaction selectivity and the yields of the target products. In contrast to the previously reported catalytic systems, the new conditions allow the use of both dialkyl- and diarylacetylenes with the same high efficiency. [ABSTRACT FROM AUTHOR]

Over the past two decades, catalytic alkyne alkoxylation-initiated Claisen rearrangement has proven to be a practical and powerful strategy for the rapid assembly of a diverse range of structurally complex molecules. The rapid development of Claisen rearrangements triggered by transition-metal-catalyzed alkyne alkoxylation has shown great potential in the formation of carbon–carbon bonds in an atom-economic and mild way. However, metal-free alkyne alkoxylation-triggered Claisen rearrangement has seldom been exploited. Recently, Brønsted acids such as HNTf2 and HOTf have been shown to be powerful activators that promote catalytic alkyne alkoxylation/Claisen rearrangement, leading to the concise and flexible synthesis of valuable compounds with high efficiency and atom economy. Recent advances on the Brønsted acid catalyzed alkyne alkoxylation/Claisen rearrangement are introduced in this Account, in which both intramolecular and intermolecular tandem reactions are discussed. [ABSTRACT FROM AUTHOR]