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We have developed a family of dinuclear complexes using 2,7‐disubstituted 1,8‐naphthalenediol ligands that bind by molecular recognition to two neighboring phosphate diesters of the DNA backbone with the dinuclear CuII and NiII complexes exhibiting a severe cytotoxicity for human cancer cells. To increase the binding affinity, we intended to synthesize the corresponding dinuclear FeIII complex. Surprisingly, we obtained a tetranuclear FeIII perylene‐based complex instead of the expected dinuclear FeIII naphthalene‐based complex. In order to establish a rational and reproducible synthesis, we carefully analyzed this reaction. This revealed a multistep oxidative cascade reaction including the pre‐coordination of FeII ions in the N3‐binding pockets, the Lewis‐acid assisted MOM‐deprotection of the pre‐ligand by the pre‐oriented FeII ions, two oxidative aromatic C−C coupling reactions, oxidation of the perylene‐based backbone and of FeII to FeIII. The careful analysis of bond lengths, HOMA indices (harmonic oscillation model of aromaticity), FTIR and UV‐Vis‐NIR spectra supported by DFT calculations reveals the presence of an aromatic 18‐electron oxidized perylenequinone ligand backbone. In summary, a multistep cascade reaction involving in total a 10‐electron oxidation has been established for the straight‐forward synthesis of an unprecedented perylenequinone‐based ligand system. [ABSTRACT FROM AUTHOR]

Polycyclic heterocycles are the most common and critical structural motifs found in a variety of natural products, medicines, fertilizers, and advanced materials. Because of their widespread use in biologically active compounds and material chemistry, functionalised dibenzo heterocyclic compounds, especially dibenzofuran, dibenzothiophene, and carbazole derivatives, garnered much attention over time. Scientists are especially interested in elucidating more efficient techniques for developing these industrially essential compounds. Dibenzo‐fused heterocycles can rapidly be synthesised using highly efficient transition metal‐catalysed strategies as well as by economic metal‐free reaction conditions. This review includes a detailed overview of the most recent significant synthetic techniques, both metal‐catalysed and metal‐free, to produce these industrially significant and medicinally important dibenzo‐fused heterocycles. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: An efficient and highly stereoselective synthetic method to access polycyclic chromanes has been achieved through organocatalyzed one‐pot step‐wise reactions involving 2‐hydroxycinnamaldehydes, 2‐aminochalcones, and malononitrile as substrates. The reactions underwent a quintuple process by aza‐Michael/Michael/Knoevenagel/oxa‐Michael/aldol‐type reaction in sequence to give products bearing 3 new generated rings and 5 chiral centers in moderate to quantitative yields with excellent stereoselectivities. A novel retro‐reaction mechanism was discovered in the synthetic transformations of products. [ABSTRACT FROM AUTHOR]

Ytterbium triflate catalysed domino reaction of (3‐formyl‐4‐indolyl)‐derived donor‐acceptor cyclopropane with primary amines provides a simple approach to an unprecedented tetracyclic skeleton in which tropane system is peri‐annulated with an indole core. This process involves the formation of an imine and its (3+2)‐cross‐cycloaddition with donor‐acceptor cyclopropane moiety, yielding tropane‐fused indole core under mild reaction conditions. These products are of significant interest for pharmacology as potential hybrid molecules with a dual mode of action. [ABSTRACT FROM AUTHOR]

This article presents trioxa[9]circulene (3) as a novel member of hetero[n]circulenes. Its synthesis began with the synthesis of dimethoxydioxa[8]helicene (5) and used dimethoxydiepoxycyclononatrinaphthalene (4) as a key intermediate, despite the condensation reaction predominantly yielding a 1,4‐addition byproduct. The structures and properties of 3–5 were extensively investigated using experimental and computational methods. Analysis of the crystal structures reveal elongation of the internal C−C bonds in the nine‐membered ring of 3 compared to 4 and 5. Computational studies demonstrate the remarkable flexibility of trioxa[9]circulene's saddle‐shaped polycyclic framework, while the other two compounds are rigid with large racemization barriers. Optically pure forms of 4 and 5 exhibit absorption and luminescence dissymmetry factors on the order of 10−2, with smaller values observed for compound 4. In the crystal structures, molecules of 3 stack to form columns with remarkable π–π overlap, and the π–π interactions of 4 exhibit short intermolecular C‐to‐C contacts. Consequently, the solution‐processed film of 4 functioned as a p‐type organic semiconductor in field effect transistors. [ABSTRACT FROM AUTHOR]

Replacement of sp2‐hybridized carbon in polycyclic aromatic hydrocarbons (PAHs) by boron affords electron‐deficient π‐scaffolds due to the vacant pz‐orbital of three‐coordinate boron with the potential for pronounced electronic interactions with electron‐rich metal surfaces. Using a diboraperylene diborinic acid derivative as precursor and a controlled on‐surface non‐covalent synthesis approach, we report on a self‐assembled chiral supramolecular kagome network on an Ag(111) surface stabilized by intermolecular hydrogen‐bonding interactions at low temperature. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal a flat band at ca. 0.33 eV above the Fermi level which is localized at the molecule center, in good agreement with tight‐binding model calculations of flat bands characteristic for kagome lattices. [ABSTRACT FROM AUTHOR]

This review centers on the synthetic strategies employed with indolyl‐ynones. Indolyl‐ynone, owing to its highly reactive ynone moiety, frequently partakes in dearomatizing spirocyclization reactions and subsequent rearrangement reactions when subjected to various reaction conditions. Hence, various heterocycles such as densely functionalized spiroindolenines, carbazoles, quinolines and carbo‐and hetero‐cycle substituted indoles are synthesized from indolyl‐ynones. In addition to this, the versatile spirocyclic indole scaffold exhibits the capability to produce tetracyclic and polyclic structures through intricate skeletal rearrangement processes. Moreover, the total synthesis of natural products using the indolyl‐ynone moiety was also compiled in this review. [ABSTRACT FROM AUTHOR]

Three small molecules consisting of thieno‐fused naphthalimide units connected via aromatic linkers were synthesized to study the effect of fused thiophene rings on the properties of naphthalimide‐based molecules. A protocol for the synthesis of thienonaphthalimide‐based molecules without prior preparation and use of thienonaphthalimide precursors and organoelement compounds (organolithium, organotin, or organoboron compounds) was developed. The protocol is based on double thienannulation of bis‐alkyne substrates with sodium sulfide. The thin‐film morphology, photophysical and electrochemical properties of the obtained small molecules were studied. Single‐layer non‐doped organic light‐emitting diodes based on fluorene‐bridged thienonaphthalimide dimer showed yellow emission with luminance of 2200 cd/m2, and current efficiency of 0.35 cd/A. Combination of transient electroluminescence and photo‐CELIV methods allowed to estimate electron and hole mobility in the synthesized compounds; both are in order of 10−6 cm2V−1 s−1. [ABSTRACT FROM AUTHOR]

This article discusses the use of gold catalysts in the construction of polycycles through the dearomatization-allenene reaction. The study focuses on the activation of carbon-carbon double and triple bonds by gold catalysts, which allows for the efficient synthesis of complex molecules. The article explores the diastereoselectivity and chirality transfer in the reaction, as well as the reaction with different nucleophiles. Quantum chemical calculations were performed to understand the reaction mechanisms and selectivities. The text also provides detailed information on the synthesis procedures and characterization of the synthesized compounds. The authors, Nina Semleit and Gebhard Haberhauer, are researchers in the field of organic chemistry at the University of Duisburg-Essen. [Extracted from the article]

Increasing the chemical diversity of organic semiconductors is essential to develop efficient electronic devices. In particular, the replacement of carbon‐carbon (C−C) bonds with isoelectronic boron‐nitrogen (B−N) bonds allows precise modulation of the electronic properties of semiconductors without significant structural changes. Although some researchers have reported the preparation of B2N2 anthracene derivatives with two B−N bonds, no compounds with continuous multiple BN units have been prepared yet. Herein, we report the synthesis and characterization of a B2N2 anthracene derivative with a BNBN unit formed by converting the BOBN unit at the zigzag edge. Compared to the all‐carbon analogue 2‐phenylanthracene, BNBN anthracene exhibits significant variations in the C−C bond length and a larger highest occupied molecular orbital–lowest unoccupied molecular orbital energy gap. The experimentally determined bond lengths and electronic properties of BNBN anthracene are confirmed through theoretical calculations. The BOBN anthracene organic light‐emitting diode, used as a blue host, exhibits a low driving voltage. The findings of this study may facilitate the development of larger acenes with multiple BN units and potential applications in organic electronics. [ABSTRACT FROM AUTHOR]

A one-pot synthesis of 4,9-dimethyl-2,3a,5a,7,8a,10a-hexaazaperhydropyrenes by the catalytic heterocyclization of 2,6-dimethyl-1,4,5,8-tetraazadecalin with a cyclomethylating reagent (formaldehyde or tetramethylmethanediamine) and substituted anilines. [ABSTRACT FROM AUTHOR]

This article presents two groups of V‐shaped π‐scaffolds that consist of two N‐heteroacene units fused with either a rigid or flexible eight‐membered ring. These rigid and flexible N‐heteroacene dimers were synthesized through the condensation of tetraphenylenetetraone with the corresponding diamine and the Pd‐catalyzed cross‐coupling of tetrabromodibenzo[a,e]cyclooctatetraene with the corresponding diamine, respectively. A comparison of electronic structures and properties of the two groups of V‐shaped N‐heteroacene dimers shows subtle difference between the rigid and flexible eight‐membered ring linkers in forming extended π‐systems. X‐ray crystallography of these V‐shaped molecules has revealed interesting π‐π interaction modes, which are dependent on the central connecting units and substituting groups. These π‐π interactions between the V‐shaped π‐scaffolds have enabled the molecules to function as organic semiconductors in solution‐processed field effect transistors. [ABSTRACT FROM AUTHOR]

The preparation of bridged bicyclooctadienes through the dearomatization of simple arenes is an interesting synthetic tool to access a vast chemical space of elegant molecular architectures from a wide range of simple and cheap building blocks. However, the energetic toll due to the loss of the aromatic stabilization has greatly limited the development of para-cycloadditions, especially with respect to intermolecular processes. We report herein the first general approach for the selective dearomatization of simple naphthalene. The visible-light-promoted reaction occurs under mild conditions over an ample range of substrates and it involves the initial sensitization of an acylallenamide. Moreover, complete control on the difunctionalization of either the internal or the terminal C–C double bond is observed depending on the substrate functionalization.

Fragments of buckminsterfullerene (C60) include the monumental three compounds corannulene, sumanene, and truxene. These three have served as leading molecules in ongoing research for curved, fused, and π‐extended polyaromatic materials. Achieving more structural variations that join the ranks of these three archetypes remains challenging. Herein we report synthesis of an octacyclic hydrocarbon that is an unexplored C60‐fragment, namely, a 4,11‐dihydrodiindeno[7,1,2‐ghi:7′,1′,2′‐pqr]chrysene (C28H16, which we named Metelykene). The key to success was solution‐compatible synthesis in which double pentagonal rings flank hexagonal ones. This solution‐phase approach, coupled with the resulting non‐planar π‐conjugation, is so straightforward that it offers an entry to a derivative such as a cardo aromatic monomer. [ABSTRACT FROM AUTHOR]

A gold‐catalyzed cascade cyclization of naphthalene‐tethered allenynes gave strained fused phenanthrene derivatives. The reaction proceeds through the nucleophilic reaction of an alkyne with the activated allene to generate a vinyl cation intermediate, followed by arylation with a tethered naphthalene ring to form the 4H‐cyclopenta[def]phenanthrene (CPP) scaffold. When using aryl‐substituted substrates on the alkyne terminus, the gold‐catalyzed reaction produced dibenzofluorene derivatives along with the CPP derivatives. Selective formation of CPP and dibenzofluorene derivatives depending on the reaction conditions is also presented. [ABSTRACT FROM AUTHOR]

A kinetically‐stabilized nitrogen‐doped triangulene cation derivative has been synthesized and isolated as the stable diradical with a triplet ground state that exhibits near‐infrared emission. As was the case for a triangulene derivative we previously synthesized, the triplet ground state with a large singlet‐triplet energy gap was experimentally confirmed by magnetic measurements. In contrast to the triangulene derivative, the nitrogen‐doped triangulene cation derivative is highly stable even in solution under air and exhibits near‐infrared absorption and emission because the alternancy symmetry of triangulene is broken by the nitrogen cation. Breaking the alternancy symmetry of triplet alternant hydrocarbon diradicals by a nitrogen cation would therefore be an effective strategy to create stable diradicals possessing magnetic properties similar to the parent hydrocarbons but with different electrochemical and photophysical properties. [ABSTRACT FROM AUTHOR]

A key challenge in the synthesis of diterpenoid alkaloids lies in identifying strategies that rapidly construct their multiply bridged polycyclic skeletons. Existing approaches to these structurally intricate secondary metabolites are discussed in the context of a "bond-network analysis" of molecular frameworks, which was originally devised by Corey some 40 years ago. The retrosynthesis plans that emerge from a topological analysis of the highly bridged frameworks of the diterpenoid alkaloids are discussed in the context of eight recent syntheses of hetidine and hetisine natural products and their derivatives. This Minireview highlights the extent to which network analyses of the type described here sufficed for designing synthesis plans, as well as areas where they had to be amalgamated with functional group oriented synthetic planning considerations.

A novel CoII -catalyzed polyene cyclization was developed that is uniquely effective when performed in hexafluoroisopropanol as the solvent. The process is presumably initiated by metal-catalyzed hydrogen-atom transfer (MHAT) to 1,1-disubstituted or monosubstituted alkenes, and the reaction is remarkable for its tolerance of internal alkenes bearing either electron-rich methyl or electron-deficient nitrile substituents. Electron-rich aromatic terminators are required in both cases. Terpenoid scaffolds with different substitution patterns are obtained with excellent diastereoselectivities, and the bioactive C20-oxidized abietane diterpenoid carnosaldehyde was made to showcase the utility of the nitrile-bearing products. Also provided are the results of several mechanistic experiments that suggest the process features an MHAT-induced radical bicyclization with late-stage oxidation to regenerate the aromatic terminator.

New molecular scaffolds of C‐, Z‐ and box‐shaped configurations are constructed by fusing phenazine and pyrene units with oxanorbornene. As revealed by X‐ray crystallography, the C‐shaped molecules exhibit two interesting π‐π stacking modes of phenazine depending on the substituting groups, and the box‐shaped molecule accommodates two chloroform molecules in the cavity and forms H‐bonds with another four molecules of chloroform. The C‐ and Z‐shaped molecules as a pair of diastereomers exhibit almost the same charge transfer absorption and emission including positive solvatochromism, indicating that the intramolecular charge transfer between pyrene (π‐donor) and phenazine (π‐acceptor) is not dependent on the overall molecular geometry. [ABSTRACT FROM AUTHOR]

As new polycyclic aromatic hydrocarbons (PAHs) containing an imide group, we designed and synthesized 2,3‐naphthalimide fused with benzothiophene 1 or benzofuran 2. 1 and 2 have a push‐pull structure attributed to the imide group and the electron‐donating heterocyclic moieties, indicated that 1 and 2 play as a fluorosolvatochromic dye. 1 and 2 were synthesized in 3‐steps. The absorption and fluorescence spectra were measured in twelve different solvents. The absorption spectra of 1 and 2 showed a slight solvent dependence. On the other hand, a strong solvent dependence was observed in the fluorescence spectra of 1 and 2, that is, fluorosolvatochromism. The plots of the emission maximum versus the solvent polarity parameter ET(30) for 1 and 2 exhibited a good linear correlation. Multiple linear regression analysis using Catalán scale suggested that the fluorescence behavior of 1 and 2 is influenced by the acidity and dipolarity of the solvents. The changes in the dipole moment between the ground and excited states estimated by the Lippert‐Mataga equation were 7.6 D for 1 and 7.2 D for 2. [ABSTRACT FROM AUTHOR]

The incorporation of heteroatoms into hydrocarbon compounds greatly expands the chemical space of molecular materials. In this context, B−N doping takes a center stage due to its isosterism with a C=C‐bond. Herein, we present a new and modular synthetic concept to access novel diazadiborabenzo[b]triphenylenes 7 a–h using the B−N doped biradical 16 as intermediate. Characterization of the photophysical properties revealed the emission spectra of the diazadibora benzo[b]triphenylenes 7 a–h can conveniently be tuned by small changes of the substitution on the boron‐atom. All of the diazadibora compounds show a short life‐time phosphorescence. Additionally, we were able to rationalize the excited‐state relaxation of the diazadiboraacene 7 a via intersystem crossing by quantum chemical calculations. The new synthetic strategy provides an elegant route to various novel B−N doped acenes with great potential for applications in molecular materials. [ABSTRACT FROM AUTHOR]

Embedding seven‐membered rings into polycyclic aromatic molecules is attractive as they can exert an influence on molecular conformation that ultimately changes the solubility and π‐electronics. The considerations in designing and synthesizing a highly strained azatriseptane framework are discussed herein. We employ a twofold macrocyclization strategy to form the [7,7,7]‐system and through scoping various strategies identify that the Friedel–Crafts approach is the key. In addition to the successes presented here, the synthetic limitations we have identified highlight the key challenges in forming triseptane frameworks and pave the way for second‐generation analogues that may have various applications in optical and electronic organic materials. [ABSTRACT FROM AUTHOR]

A series of Diels–Alder reactions between the diene 2,2'‐biaceanthrylene and several dienophiles is presented. The diene is a cyclopenta‐fused polycyclic aromatic hydrocarbon with anthracene units linked by two cyclopentene rings. Depending on the dienophile, the major product was the result of a single addition (dimethyl acetylenedicarboxylate) or double addition (quinone, benzyne) to the diene. Single crystal X‐ray analysis of the quinone‐derivative shows a propeller‐like structure composed of mixed enantiomers. The synthesis and photophysical properties of these compounds are presented. [ABSTRACT FROM AUTHOR]

A novel, benign synthetic strategy towards soluble tetra(peri‐naphthylene)anthracene (TPNA) decorated with triisopropylsilylethynyl substituents has been established. The compound is perfectly stable under ambient conditions in air and features intense and strongly bathochromically shifted UV/vis absorption and emission bands reaching to near‐IR region beyond 900 nm. Cyclic voltammetry measurements revealed four facilitated reversible redox events comprising two oxidations and two reductions. These remarkable experimental findings were corroborated by theoretical studies to identify the TPNA platform a particularly useful candidate for the development of functional near‐IR fluorophores upon appropriate functionalization. [ABSTRACT FROM AUTHOR]

Chiral nanographenes with both high fluorescence quantum yields (ΦF) and large dissymmetry factors (glum) are essential to the development of circularly polarized luminescence (CPL) materials. However, most studies have been focused on the improvement of glum, whereas how to design highly emissive chiral nanographenes is still unclear. In this work, we propose a new design strategy to achieve chiral nanographenes with high ΦF by helical π‐extension of strongly luminescent chromophores while maintaining the frontier molecular orbital (FMO) distribution pattern. Chiral nanographene with perylene as the core and two dibenzo[6]helicene fragments as the wings has been synthesized, which exhibits a record high ΦF of 93 % among the reported chiral nanographenes and excellent CPL brightness (BCPL) of 32 M−1 cm−1. [ABSTRACT FROM AUTHOR]

Any singular irreducible cubic curve (or simply, cubic) after an affine transformation can be written as either y 2 = x 3 , or y 2 = x 2 (x + 1) , or y 2 = x 2 (x − 1). We classify the phase portraits of all quadratic polynomial differential systems having the invariant cubic y 2 = x 2 (x + 1). We prove that there are 6 3 different topological phase portraits for such quadratic polynomial differential systems. We control all the bifurcations among these distinct topological phase portraits. These systems have no limit cycles. Only three phase portraits have a center, 19 of these phase portraits have one polycycle, three of these phase portraits have two polycycles. The maximum number of separartices that have these phase portraits is 26 and the minimum number is nine, the maximum number of canonical regions of these phase portraits is seven and the minimum is three. [ABSTRACT FROM AUTHOR]

Our present study provides expedient methods for the synthesis of novel substituted indanes, pyrido[3,2,1-jk]carbazoles and pyrido[3,2,1-kl]phenothiazines utilizing intramolecular Friedel-Crafts cyclialkylations of synthesized heteroaryl alcohols. This methodology is realized by a three-step protocol involving first esterification of starting carboxylic acids to the corresponding esters, addition of Grignard reagents to give carbinol precursors and followed by Friedel-Crafts cyclizations of alcohols mediated by AlCl3/CH3NO2, PPA or P2O5-catalysts to furnish the desired polycycles in good to excellent yields of 65-85%. The designed protocol offers easy access to the pharmaceutically promising templates in good yields. The molecular structural elucidations of all newly obtained compounds have been proved by spectral and elemental analysis. [ABSTRACT FROM AUTHOR]

Under the open‐vessel atmosphere conditions, the one‐pot synthesis of bis‐sulfonyl dibenzooxabicyclo[5.5.0]dodecanes was developed by double substitution of 1,3‐dichloroacetone with arenesulfinic acid sodium salts, and C‐ and O‐alkylation of the resulting 1,3‐bis‐sulfonylacetones with 2 equivalents of o‐bis(bromomethyl)arenes. A plausible mechanism is proposed and discussed. This high‐yielding protocol provides an intermolecular substitution and an intramolecular ring‐closure via the formations of three carbon−carbon single (C−C) bonds, two carbon−sulfur single (C−S) bonds, and one carbon−oxygen single (C−O) bond. [ABSTRACT FROM AUTHOR]

Gold(I)‐catalyzed cyclization of o‐alkenyl‐o'‐alkynylbiaryls in the presence of external or internal nucleophiles provides a straightforward access to phenanthrene‐based polycycles, which are of considerable interest in materials science. Thus, their reactions with alcohols yield functionalized dihydrophenanthrenes, in a process that can also be carried out intramolecularly, to provide phenanthrene‐derived heteropolycyclic compounds. Moreover, benzo[b]triphenylenes can be synthesized from o‐methoxyvinyl‐o'‐alkynylbiaryls, in a reaction in which an (hetero)aryl substituent at the triple bond acts as an internal nucleophile. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Two novel boron (B), sulfur (S), nitrogen (N)‐doped polycyclic aromatic hydrocarbon multiple resonance emitters (DBNS and DBNS‐tBu) are designed and synthesized for narrowband red emission by embedding two pairs of S and N atoms and two B atoms in para‐positions of central benzene rings within a tridecacyclic aromatic skeleton to form donor‐π‐donor (D‐π‐D) and acceptor‐π‐acceptor (A‐π‐A) structures, which not only exhibit emission maximum at 641 nm with small full width at half maximum of 39 nm, but also combine high photoluminescent quantum efficiency (85%) and rapid reverse intersystem crossing (kRISC = 2.2 × 105 s−1), giving rise to red electroluminescence with color coordinates of (0.65, 0.34) and maximum external quantum efficiency of 7.8% via solution process. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Two novel boron (B), sulfur (S), nitrogen (N)‐doped polycyclic aromatic hydrocarbon multiple resonance emitters (DBNS and DBNS‐tBu) are designed and synthesized for narrowband red emission by embedding two pairs of S and N atoms and two B atoms in para‐positions of central benzene rings within a tridecacyclic aromatic skeleton to form donor‐π‐donor (D‐π‐D) and acceptor‐π‐acceptor (A‐π‐A) structures, which not only exhibit emission maximum at 641 nm with small full width at half maximum of 39 nm, but also combine high photoluminescent quantum efficiency (85%) and rapid reverse intersystem crossing (kRISC = 2.2 × 105 s−1), giving rise to red electroluminescence with color coordinates of (0.65, 0.34) and maximum external quantum efficiency of 7.8% via solution process. [ABSTRACT FROM AUTHOR]

A modular synthesis of both difurooxa‐ and difuroazadiborepins from a common precursor is demonstrated. Starting from 2,2′‐bifuran, after protection of the positions 5 and 5' with bulky silyl groups, formation of the novel polycycles proceeds through opening of the furan rings to a dialkyne and subsequent re‐cyclization in the borylation step. The resulting bifuran‐fused diborepins show pronounced stability, highly planar tricyclic structures, and intense blue light emission. Deprotection and transformation into dibrominated building blocks that can be incorporated into π‐extended materials can be performed in one step. Detailed DFT calculations provide information about the aromaticity of the constituent rings of this polycycle. [ABSTRACT FROM AUTHOR]

Design, synthesis, and isolation of a Kekulé hydrocarbon with a triplet ground state is described. Its triplet ground state was unambiguously confirmed by ESR experiments, and the structure and fundamental physical properties were also revealed. The key feature of the molecular design is the decrease in the bonding interaction in the singlet state by aromatic stabilization of benzene rings and the increase of the exchange interaction of unpaired electrons which are favorable for the triplet state. These results contribute to the development of hydrocarbon‐based organic magnetic materials. [ABSTRACT FROM AUTHOR]

Herein, we report a visible‐light‐induced [2+2+1] dearomative cascade cyclization of indole/furan alkynes with NaHSO3, providing an array of diverse highly strained sulfonyl polycycles. Compared to our previous work, this method does not require the use of additional sacrificial oxidants and have wider reaction scope. Preliminary mechanistic studies suggest that the indole moiety initiated the reaction, which proceeded via single‐electron oxidation pathway. An alkenyl radical formed by intramolecular addition capture SO2, and the resulting specie is cyclized to furnish the final product. Also, DFT calculations disclosed that the groups on the indole ring or at the side chain probably affect the single electron distribution at the reaction site of IM‐RC‐I, and the distribution may be a decisive factor of spirocyclization. [ABSTRACT FROM AUTHOR]

A two‐step synthesis of less accessible spiro[cyclobutene‐1,9′‐fluorene] compounds from biaryl‐alkynes and 2‐(2‐fluoropyridin‐1‐ium‐1‐yl)‐1,1‐bis((trifluoromethyl)sulfonyl)ethan‐1‐ide, which serves as a potent precursor for outstandingly electrophilic Tf2C=CH2, has been developed. This synthetic methodology includes selective formation of gem‐bis(triflyl)cyclobutenes from biaryl‐alkynes and Tf2C=CH2 followed by desulfinative spirocyclisation mediated by 1,1,1,3,3,3‐hexafluoroisopropyl alcohol (HFIP). Besides, on the basis of the chameleonic reactivity of sulfone functionality, several derivatisations of triflylated spiro[cyclobutene‐1,9′‐fluorene] products have been successfully achieved. [ABSTRACT FROM AUTHOR]

A set of building blocks based on the 4,5,6,7‐tetrahydro‐pyrazolo[1,5‐a]pyrazine scaffold is synthesized in a multigram scale in a cost‐efficient manner. The possibility of the introduction of different substituents, neutral or functionalized in different positions of pyrazole and/or piperazine rings, is shown. The efficacy of using NH‐pyrazole carbonic acids as a key intermediate of the process is demonstrated. The regioselectivity for direct insertion of the substituent to the 4,5,6,7‐tetrahydro‐pyrazolo[1,5‐a]pyrazine core is discussed. The synthetic perspectives for using the functionalized 4,5,6,7‐tetrahydro‐pyrazolo[1,5‐a]pyrazine as a bifunctional scaffold is discussed. The utilizing of building blocks obtained for the different region‐ and/or stereoselective synthesis, including sole transformations or modifications of functional groups, is demonstrated. The advantages of the proposed approach are proven compared with the other known methodologies. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are promising nanocarbon materials with diverse optoelectronic properties, yet they also pose concerning environmental and health risks. Despite the ubiquity of PAHs in the environment (crude oil, emissions, and biomass), most supermolecules rely on heteroatoms for stability. We discovered and characterized a family of all-hydrocarbon, all-π-conjugated [n]cycloparaphenylene-PAH host-guest complexes. We built a theoretical framework to rapidly select these complexes and predict their stabilities, driven exclusively by CH−π interactions. More than a dozen complexes were confirmed experimentally and assembled directly from commercially available compounds. This motif offers a versatile way to combine the advantageous properties of organic semiconductors with the rich dynamic, stereochemical, stimulus-responsive, and stress-dissipative behavior of host-guest complexes, while creating new opportunities for bespoke PAH separation or remediation materials. [ABSTRACT FROM AUTHOR]

Microwave irradiation and post-Ugi reactions own their respective advantages in comparison with other strategies. The combination of microwave irradiation and post-Ugi reactions shows paramount importance in the construction of polycycles. This minireview outlines the recent developments of microwave-assisted post-Ugi reactions for the synthesis of polycycles. Through transition metal-catalyzed or transition metal-free transformations, diverse polycycles are prepared in an efficient, rapid, and step-economical manner. [ABSTRACT FROM AUTHOR]

A series of triazabenzo[a]pyrenes comprising a cata‐condensed pyridine ring and 4,10‐diazapyrene framework were synthesized from commercially available materials in the following three steps: palladium‐catalyzed direct C−H arylation, nucleophilic addition of Grignard reagents to cyano groups, and copper‐catalyzed oxidative C−N bond formation. The triazabenzo[a]pyrenes showed superior electron‐accepting properties and narrower HOMO‐LUMO energy gaps compared to the corresponding 4,10‐diazapyrene derivative because of the condensation of an electron‐deficient pyridine ring. The photophysical, acid‐responsive, and electrochemical properties of triazabenzo[a]pyrenes depend on the position of the nitrogen atom in the cata‐condensed pyridine ring. Density functional theory calculations revel that the condensation of a pyridine ring leads to a lowering of the LUMO energy level thereby enhancing the electron‐accepting properties. [ABSTRACT FROM AUTHOR]

[Display omitted] Novel terpenoid dimers linked through the E–E rings were synthesized by catalytic multicomponent condensation of amino derivatives of methyl maleopimarate with form-aldehyde and dimethyl-tetraazadecalin or tetraazaperhydro- tetracene. Primary screening of the synthesized terpenoid dimers for cytotoxic activity was performed. [ABSTRACT FROM AUTHOR]

Convergent routes to various six-membered carbocyclic architectures exploiting the unique radical chemistry of xanthates are described in this brief review. Three approaches are discussed. The first is the modification of existing cyclohexane building blocks, namely, cyclohexanones, cyclohexenones and cyclohexenes. The second deals with the construction of six-membered carbocycles by associating the chemistry of xanthates with classical ionic reactions, especially the Robinson annulation, the Michael addition and the Horner–Wadsworth–Emmons condensation. Finally, the third route is the formation of six-membered rings by direct six- exo and, but more rarely, six- endo cyclisation modes. Many of the complex structures presented herein would be tedious to obtain by more traditional methods. [ABSTRACT FROM AUTHOR]

Herein we devise and execute a new synthesis of a pristine boron‐doped nanographene. Our target boron‐doped nanographene was designed based on DFT calculations to possess a low LUMO energy level and a narrow band gap derived from its precise geometry and B‐doping arrangement. Our synthesis of this target, a doubly B‐doped hexabenzopentacene (B2‐HBP), employs six net C−H borylations of an alkene, comprising consecutive hydroboration/electrophilic borylation/dehydrogenation and BBr3/AlCl3/2,6‐dichloropyridine‐mediated C−H borylation steps. As predicted by our calculations, B2‐HBP absorbs strongly in the visible region and emits in the NIR up to 1150 nm in o‐dichlorobenzene solutions. Furthermore, B2‐HBP possesses a very low LUMO level, showing two reversible reductions at −1.00 V and −1.17 V vs. Fc+/Fc. Our methodology is surprisingly selective despite its implementation of unfunctionalized precursors and offers a new approach to the synthesis of pristine B‐doped polycyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

This study explored new polycyclic conjugated scaffolds combining pyrene and cyclobutadienoid rings. Regioisomeric bis(naphthocyclobuta)pyrenes were synthesized and characterized by single‐crystal X‐ray crystallography. It was found that the regioisomeric polycyclic conjugated scaffolds exhibit different local aromaticity and photophysical properties as a result of the different fusion patterns of pyrene and cyclobutadienoid. Tuning the π‐stacking of bisnaphtho[2′,3′:3,4]cyclobuta[1,2‐e:1′,2′‐l]pyrene by changing the length of the alkyl substituents led to a p‐type organic semiconductor for solution‐processed thin film transistors. [ABSTRACT FROM AUTHOR]

We study bifurcations in finite-parameter families of vector fields on. Recently, Yu. Ilyashenko, Yu. Kudryashov, and I. Schurov provided examples of (locally generic) structurally unstable -parameter families of vector fields: topological classification of these families admits at least one numerical invariant. They also provided examples of -parameter families such that the topological classification of these families has at least numerical invariants and used those examples to construct families with functional invariants of topological classification. In this paper, we construct locally generic -parameter families with any prescribed number of numerical invariants and use them to construct -parameter families with functional invariants. We also describe a locally generic class of -parameter families with a tail of an infinite number sequence as an invariant of topological classification. [ABSTRACT FROM AUTHOR]

Rapid molecular‐weight growth of hydrocarbons occurs in flames, in industrial synthesis, and potentially in cold astrochemical environments. A variety of high‐ and low‐temperature chemical mechanisms have been proposed and confirmed, but more facile pathways may be needed to explain observations. We provide laboratory confirmation in a controlled pyrolysis environment of a recently proposed mechanism, radical–radical chain reactions of resonance‐stabilized species. The recombination reaction of phenyl (c‐C6H5) and benzyl (c‐C6H5CH2) radicals produces both diphenylmethane and diphenylmethyl radicals, the concentration of the latter increasing with rising temperature. A second phenyl addition to the product radical forms both triphenylmethane and triphenylmethyl radicals, confirming the propagation of radical–radical chain reactions under the experimental conditions of high temperature (1100–1600 K) and low pressure (ca. 3 kPa). Similar chain reactions may contribute to particle growth in flames, the interstellar medium, and industrial reactors. [ABSTRACT FROM AUTHOR]

The synthesis of several centrotriindanes bearing ortho‐phenyl groups in the sterically constricted bay regions is described. The classical three‐step sequence including twofold cyclodehydration of the corresponding 2,2‐dibenzyl‐1,3‐indanediols afforded an angular difuso‐triidane and several all‐cis‐tribenzo[5.5.5.6]fenestranols equipped with two or four ortho‐phenyl groups. In contrast to the construction of these conformationally flexible centrotriindanes, attempts to synthesize ortho,ortho‐diphenyl‐substituted tribenzotriquinacenes failed due to the increased rigidity of the TBTQ skeleton. The high steric load imposed by the para‐terphenyl moieties affects the spirocyclization between 1,3‐indanedione and 1,5‐di‐(para‐2′‐terphenylyl)pentadienone, kinetic control of which is critical to access the all‐cis‐tribenzo[5.5.5.6]fenestrane framework. In contrast, the corresponding tetraphenyl‐cis,cis,cis,trans‐tribenzo[5.5.5.6]fenestranol is easily accessible. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Stimuli‐responsive molecules are highly desirable in different scenario such as smart materials, bio‐imaging, and environment monitoring. Herein, a series of hetero polycycles which show optical response toward chemical stimuli are synthesized from trithiasumanene (TTS). The TTS is transformed into ortho‐quinone form, which then undergoes three‐component Debus‐Radziszewski reaction with aldehydes and ammonia to give oxazole‐fused TTS (2—6). The thiophene rings on 3—5 are selectively oxidized to thiophene‐S,S‐dioxides, affording 3‐3O2—5‐3O2. It is found that the electronic structures of these compounds are governed by the substituents on oxazole moiety and oxidation state of thiophene ring. Moreover, these hetero polycycles exhibit optical response toward different chemical stimuli. Particularly, compounds 6 and 3‐3O2 can serve as fluorescence detectors for harmful chemicals sulfide ions (S2–/HS–) and aniline, respectively. This work indicates that TTS is a promising precursor for the creation of responsive materials. [ABSTRACT FROM AUTHOR]

The benzocyclobutene (BCB) moiety is present in several bioactive natural products and medicinally interesting molecules. BCB is also a valuable synthon for building a variety of polymers by the virtue of its propensity to undergo polymerization. The research on BCB chemistry has grown in the last few decades due to its unique applications in various fields of science. In this review, we have included various methods for the preparation of BCBs and highlighted their applications in the construction of diverse complex structural frameworks. We believe that this review will be useful to synthetic chemists and polymer scientists, and we anticipate several new applications will emerge in this promising area. [ABSTRACT FROM AUTHOR]

The carboarylation reaction of biphenyl‐alkynes was successfully triggered by electrophilic attack of 1,1‐bis(triflyl)ethylene on the alkyne moiety to give polycyclic aromatic hydrocarbons (PAHs) decorated by superacidic carbon acid functionality. Neutralisation of thus obtained acids with NaHCO3 yielded the corresponding sodium salts, which showed improved solubility in both aqueous and organic solvents. [ABSTRACT FROM AUTHOR]

The commercially available n-type semiconductive dye Violanthrone 79 was used as starting material to synthesize previously unexplored substituted violanthrenes through a reductive aromatization and functionalization strategy. By using the low-cost reducing agents zinc and sodium dithionite in combination with suitable electrophilic trapping reagents, three violanthrenes functionalized with two pivalyloxy, trimethylsiloxy, or methoxy groups were selectively obtained in high yields. Due to their octyl ether moieties, these new red dyes are highly soluble. They were characterized by means of UV/vis and fluorescence spectroscopy, and their redox properties were studied by cyclic voltammetry. The spectroscopically determined frontier molecular orbital energies are compared to those calculated by density functional theory and suggest that electron-deficient Violanthrone 79 was transformed into three electron-rich violanthrenes with molecular characteristics typically observed in molecular precursors for p-type organic semiconductors. [ABSTRACT FROM AUTHOR]