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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]

The first synthesis of 2,9-disubstituted cis-2,3a,7b,9,10a,14b-hexaazaperhydrodibenzotetracenes has been accomplished through intermolecular heterocyclization of N,N-bis(methoxymethyl) alkylamines with cis-1,6,7,12-tetraazaperhydrotetracene in the presence of SmCl3·6H2O catalyst or by recyclization of 1,3,5-tricycloalkyl-1,3,5-triazinanes with cis-1,6,7,12-tetraazaperhydrotetracene in the presence of NiCl2·6H2O catalyst. The structures were established by 1D (1H, and 13C) and 2D (HSQC, HMBC, COSY, NOESY) NMR spectroscopy, MALDI TOF/TOF mass spectrometry, and X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

Conjugated ladder-type oligomers are a class of important functional organic materials. They possess intriguing properties stemming from their fully fused aromatic backbones. The construction of the ladder-type backbone relies on a 'ladderization' step, which may be accomplished through either kinetically or thermodynamically controlled annulation reactions. The attributes of these reactions are discussed, with relevant recent examples. The development of these reactions is key to continued advances and innovation in the field of organic conjugated materials. 1 Introduction 2 Kinetic Annulations 3 Thermodynamic Annulations 4 Future Outlooks and Conclusion [ABSTRACT FROM AUTHOR]

A new approach has been developed for the synthesis of 1-substituted 3α,6α-diarylglycolurils from an imidazolone, imidazooxazolone, imidazooxazinone, or imidazooxazepinone and urea in the presence of hydrochloric acid. The structure of 1-ethyl-3α,6α-diphenylglycoluril was confirmed by X-ray diffraction studies. [ABSTRACT FROM AUTHOR]

Annulated arenes and hetarenes were prepared in good to very good yields by hydriodic acid/red phosphorus mediated reductive cyclization of 3-(hetero)aryl phthalides. The reductive cyclization also proceeded successfully with 2-aroylbenzoic acids and 2-aroylnaphthoic acids. [ABSTRACT FROM AUTHOR]

17H-Tetrabenzo[a,c,g,i]fluoren-17-one possessing a nonplanar, helicene-like structure was efficiently prepared by aerial oxidation of 17H-tetrabenzo[a,c,g,i]fluorene under mild basic conditions. A quinone methide and an unsymmetrical fulvalene containing a tetrabenzofluorene unit were synthesized from the ketone. Treatment of 17-bromotetrabenzo[ a,c,g,i]fluorene with a base afforded a symmetric fulvalene as an air-sensitive blue solid. Electrochemical analyses revealed that these compounds have high electron affinities. [ABSTRACT FROM AUTHOR]

A novel simple synthesis of bicyclo[6.n.0] (n = 3, 4) frameworks from various bisdienes by rhodium-catalyzed [4+4] cycloaddition has been developed. The reaction tolerates carbon or heteroatoms in the tether between the diene moieties. [ABSTRACT FROM AUTHOR]

A simple and efficient one-pot method is described for the construction of [1,4]thiazepino[5,4-a]isoquinolines containing intramolecular hydrogen bonds by a sequential four-component domino reaction of isoquinoline, a 2-bromoacetophenone, an aryl isothiocyanate, and dimethyl acetylenedicarboxylate. [ABSTRACT FROM AUTHOR]

Through careful choice of conditions, 2-(N-indolyl) amides can be directed to undergo selectively either enolate arylation to give oxindoles or direct arylation to give indolo-fused benzodiazepines. The former chemistry facilitates the synthesis of the hexahydropyrrolindole core of psychotrimine. [ABSTRACT FROM AUTHOR]

The synthesis of novel heterocyclic [1,2,4]triazolo[3,4- b][1,3,4]thiadiazine hybrids by a bimolecular reaction of 2-(4-amino-5- mercapto-4H-[1,2,4]triazol-3-yl)phenol with an aromatic or heterocyclic α-bromoacetyl derivatives is described. This synthetic procedure starts from an unprotected phenol. [ABSTRACT FROM AUTHOR]

A general and highly selective method for the synthesis of 4-substituted 3a,6a-diphenyltetrahydro-2H-imidazo[4,5-d][1,3]thiazole-2,5(3H)-diones has been developed through a new reaction of 1-substituted 5-hydroxy-4,5-diphenyl-1H-imidazol-2(5H)-ones with potassium thiocyanate in the presence of acetic acid in acetonitrile. Details of supramolecular organization in the crystalline imidazothiazolones, as revealed by X-ray diffraction, are highlighted. [ABSTRACT FROM AUTHOR]

Synthetic studies on huperzine R are described. The 1-azabicyclo[ 5.4.3]tetradec-6-ene core was constructed by elimination of an ammonium salt formed at a position β to a carbonyl group. [ABSTRACT FROM AUTHOR]

The synthesis of the first ring-functionalized heliphenes is described, comprised of angular 1,2-di-, 2,3-di-, and 1,2,15,16-tetrachloro[6]phenylene, via a series of Sonogashira couplings and cobalt-catalyzed alkyne cyclotrimerization steps. These molecules are explored as potential precursors to antikekulene and their reactivity compared to that of the parent angular [6]phenylene. An X-ray structural determination of 1,2,15,16-tetrachloro[6]phenylene reveals a structure with a considerably larger helical separation than in [6]phenylene, caused by the bulk of the appended chlorine atoms. [ABSTRACT FROM AUTHOR]

Manganese dioxide mediated oxidative cleavage of 1,3-disubstituted benzo[c]furans in dichloromethane at room temperature gave good yields of 1,2-di(het)aroylbenzenes [ABSTRACT FROM AUTHOR]

This article outlines the efforts toward the synthesis of heterasumanene, a buckybowl consisting of four six-membered and three five-membered rings. Special attention is paid to our achievement on the facile and large-scale synthesis of trithia- and triselenasumanenes. [ABSTRACT FROM AUTHOR]

A simple and versatile route to 1,2-disubstituted acenaphthylenes has been developed. The method involves palladiumcatalyzed annulation of 1,8-dibromonaphthalene or 5,6-dibromoacenaphthylene with an internal alkyne, and does not require any organometallic reagent. A range of 1,2-disubstituted acenaphthylenes and 5,6-disubstituted 1,2-dihydrocyclopenta[f,g]acenaphthylenes were prepared in moderate to good yields. The method provides a rapid and simple route to dibenzo[j,l]fluoranthene through an Ullmann coupling. [ABSTRACT FROM AUTHOR]

Indoxamycins A–F represent a novel class of polyketides isolated from saline cultures of actinomycetes. Owing to their stereochemically congested tricyclic structure and potent biological activities, indoxamycins are attractive targets for synthetic chemists. This report discusses recent progress toward the total synthesis of indoxamycins both by Carreira's group and ours. [ABSTRACT FROM AUTHOR]

A simple and highly efficient synthesis of 2-substituted quinazolin-4(3H)-ones by the iron(III) chloride catalyzed reaction of isatoic anhydride with various amidoxime derivatives was developed. Several aryl and alkyl amidoximes were screened to demonstrate the scope of the methodology. [ABSTRACT FROM AUTHOR]

A mild, simple, and general method has been developed for the synthesis of phenazines by cross-coupling of benzoquinones with o-phenylenediamines. Benzoquinones and o-phenylenediamines reacted smoothly to give the corresponding cross-coupled products in good to excellent yields. 1,4-Naphthoquinone also coupled with o-phenylenediamines in the presence of copper acetate at 50 °C to give the corresponding benzo[a]phenazines. All reactions could be carried out under air. [ABSTRACT FROM AUTHOR]

Polycyclic aromatics have attracted much research interest owing to their promising applications in supramolecular chemistry and organic electronics. Much research focuses on developing novel polycyclic aromatics with diverse properties. Among various synthetic methodologies for constructing polycyclic aromatics, iron(III) chloride (FeCl3) promoted cyclization has been extensively utilized in the synthesis of such organic π-conjugated materials. In this account, we summarize investigations of the FeCl3-promoted cyclization reaction, the construction of a series of polycyclic aromatics through this method, and the applications of such compounds in thin-film transistors and functional nanomaterials and nanodevices. [ABSTRACT FROM AUTHOR]

This article outlines our recent efforts to synthesize (+)-fusarisetin A, a naturally occurring 3-acyltetramic acid, by a route based on a hypothetical biosynthesis. Our research suggests that the biosynthesis of (+)-fusarisetin A might involve the aerobic oxidation of equisetin, possibly mediated by metal oxidants or by photochemically produced reactive oxygen species [ABSTRACT FROM AUTHOR]

Novel hydroxylated polyfunctionalized benzo[c]coumarins were synthesized by a new one-pot reaction of an unprotected monohydroxy-3-(acetoacetyl)coumarin as an active methylene Michael donor with 4-oxo-4H-chromene-3-carboxylic acid as a Michael acceptor in the presence of a catalytic amount of 4-pyrrolidin- 1-ylpyridine. An organobase-catalyzed tandem 1,4-conjugate addition, decarboxylation and aromatization reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

The regioselective 1,6-conjugate addition of ethyl malonate and malononitrile to (E)-2-styrylchromones is described. A synthesis of novel pentasubstituted spirocyclohexanes discovered during the course of these studies is also discussed. A novel domino multicomponent 1,6-/1,6-/1,4-conjugate addition reaction for the formation of these new spirocyclohexanes is proposed. [ABSTRACT FROM AUTHOR]

Asymmetric alkyne addition to aldehydes catalyzed by our BINOL-based (BINOL = 1,1'-bi-2-naphthol) catalyst system has allowed easy access to a variety of functionalized chiral propargylic alcohols with high enantiomeric purity. This article summarizes our work on using these chiral propargylic alcohols for the synthesis of structurally diverse organic molecules. Optically active tetronic acids and aminofuranones have been synthesized by the regiospecific hydration and amine addition, respectively, of chiral γ-hydroxy-α,β-acetylenic esters, a type of functionalized propargylic alcohol. Ruthenium-carbene-catalyzed ring-closing metathesis and octacarbonyldicobalt(0)-mediated Pauson- Khand (PK) cycloadditions have been used to convert propargylic alcohol based enynes into optically active mono- and bicyclic products, respectively. A chiral propargylic alcohol derived dienediyne has been subjected to a rhodium(I)-catalyzed PK cycloaddition, followed by enyne metathesis catalyzed by the Grubbs II catalyst and a Diels-Alder reaction, leading to the formation of a polycyclic product with high chemo- and stereoselectivity. Finally, a highly chemo- and stereoselective domino PK/[4+2] cycloaddition of a series of optically active trienynes has been discovered to quickly generate tetracyclic products that contain a spirocyclic framework and a quaternary carbon center. This work demonstrates that the BINOL-catalyzed asymmetric addition of alkynes to aldehydes is a very useful process for the asymmetric synthesis of structurally diverse organic products. 1 Introduction 2 Conversion of γ-Hydroxy-α,β-acetylenic Esters 2.1 Conversion into Tetronic Acids 2.2 Conversion into Aminofuranones 2.3 Conversion into γ-Acetoxy-Substituted Dienoates 3 Conversion of Chiral Propargylic Alcohol Based Enynes 3.1 Conversion into Cycloalkenes by Ring-Closing Metathesis 3.2 Conversion into Bicyclic Products by Intramolecular Pauson-Khand Cycloaddition 3.2.1 Using Chiral Enynes Derived from Pent-4-enal To Generate Fused 5,5-Bicyclic Products 3.2.2 Using Chiral Enynes Derived from Hex-5-enal To Generate Fused 6,5-Bicyclic Products 3.2.3 Using Chiral Allyl Propargyl Ethers for the Pauson-Khand Reaction 3.2.4 Discussion about the Stereoselectivity of the Intramolecular Pauson-Khand Reaction 4 Conversion of Chiral Propargylic Alcohol Based Enediynes 4.1 Preparation of Optically Active Dienediynes and Their Conversion into Bicyclic Products Using the Pauson- Khand Reaction 4.2 Ring-Closing Metathesis To Construct 5,5,7- and 5,5,8-Tricyclic Compounds 4.3 Using the Highly Diastereoselective Diels-Alder Reaction To Construct a Fused 5,5,7,6-Polycyclic Compound 4.4 Reversing the Diastereoselectivity of the Rhodium(I)-Catalyzed Pauson-Khand Cycloaddition of Chiral Enediynes 5 Conversion of Chiral Propargylic Alcohol Based Trienynes 5.1 Domino Pauson-Khand/[4+2] Cycloaddition of Optically Active Trienynes in the Presence of [RhCl(CO)2]2 5.2 Proposed Mechanistic Explanation for the Chemo- and Stereoselectivity of the Domino Pauson-Khand/[4+2] Cycloadditions 5.3 Related Catalytic Conversion of a Chiral Dienediyne in the Presence of [RhCl(CO)2]2 6 Summary. [ABSTRACT FROM AUTHOR]

In this account, we describe our efforts in developing the chemistry of the highly luminescent dithieno[3,2-b:2′,3′-d]phosphole system over the last ten years. We provide an overview of the synthetic possibilities and the inherent tunability of the emission properties offered by this particular heterole. 1 Introduction 2 Synthesis and Properties of Dithieno[3,2-b:2′,3′-d]phospholes 3 Functionalization of Dithieno[3,2-b:2′,3′-d]phospholes 3.1 Phosphorus Functionalization 3.2 Functionalization at the 2- and 6-Positions 3.2.1 Symmetric Functionalization 3.2.2 Asymmetric Functionalization 3.3 Incorporation of Fused Rings onto the Main Scaffold 4 Photophysical Properties 5 Conclusion [ABSTRACT FROM AUTHOR]

Diels-Alder reactions of 2-vinylindoles with cyclic carbo- and heterodienophiles, in the presence of suitable Lewis acids, led to uncommon [c]-carbo- and furoannulated tetrahydrocarbazoles. The obtained compounds encompass a carbonyl group in an angular position, suitable for further transformations, and represent useful intermediates for the synthesis of more complex structures. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed cycloaddition reactions of 1,8-diethynylnaphthalene derivatives with o-diiodoarenes take place to generate the corresponding benzo[k]fluoranthene-based linear acenes in moderate to good yields. In addition, 1-ethynyl-8-iodonaphthalenes undergo palladium-catalyzed cyclodimerizations to produce zethrenes. Finally, in the presence of a catalytic system comprised of [NiBr2(dppe)/Zn], 1-ethynyl-8-iodonaphthalenes reacts with nitriles and 2-butyne to form the respective pyrroloarenes and pyrene. [ABSTRACT FROM AUTHOR]

Rhodium complexes of N-heterocyclic carbenes (NHC) [RhCl(cod)(NHC)], [cod = 1,5-cyclooctadiene, NHC = 1,3-diisopropylimidazolin-2-ylidene, and NHC = 1,3-dimesitylimidazolin-2-ylidene] are tested for intra- and partially intramolecular [2+2+2]-cycloaddition reactions demonstrating their effectiveness in this kind of process. This is the first use of a rhodium-NHC complex in a [2+2+2]-cycloaddition reaction of three alkynes. ESI-MS has been used to detect oxidative addition intermediates using rhodium NHC as the catalytic system. [ABSTRACT FROM AUTHOR]

Evidence for the formation of an ovoid chiral cage, resulting from the auto-assembly of two hexafunctional and three tetrafunctional modules reacting through dynamic covalent bond formation, is provided. [ABSTRACT FROM AUTHOR]

A variety of olefin-metathesis protocols have been used to prepare spirocyclic compounds, cyclic sulfones, and constrained α-amino acid derivatives. Conceptually, a new approach to a novel cyclophane ring system has been realized via ring-closing meta�thesis (RCM). Also, tetracyclic compounds related to anthracycline antibiotics have been assembled using Claisen rearrangement and RCM as key steps. Further, a sequential use of the Diels-Alder �reaction and ring-opening cross-metathesis delivered highly functionalized spiroindane derivatives, and trisubstituted benzene derivatives have been assembled using Grubbs’ catalyst. Finally, the enyne and cross-enyne metathesis sequences have been used to prepare several constrained α-amino acid derivatives. 1 Introduction 2 Application of Ring-Closing Metathesis To Give Spiro�cyclic Compounds 3 Application of Ring-Closing Metathesis To Give Cyclophane Derivatives 4 Application of Ring-Closing Metathesis To Give Cyclic Sulfone Derivatives 5 Application of Ring-Closing Metathesis To Give Cyclic α-Amino Acid Derivatives and Modified Peptides 6 Application of Ring-Closing Metathesis to Benzannulation 7 Application of Enyne Metathesis to the Synthesis of Constrained α-Amino Acid and Naphthoxepin Derivatives 8 Application of Cross-Enyne Metathesis to the Synthesis of Highly Functionalized Phenylalanine Derivatives 9 Application of Ring-Opening Cross-Metathesis to Spiro�indanes 10 Synthesis of Trisubstituted Benzene Derivatives Using Grubbs’ Catalyst 11 Metathesis of a Novel Enyne System 12 Macroheterocycles via Cross-Enyne and Ring-Closing Metathesis Cascade Reactions 13 Conclusions [ABSTRACT FROM AUTHOR]

A new synthetic route for biologically interesting polycycles with a citran and a cyclol nucleus was developed starting from several substituted trihydroxybenzenes. This methodology was applied successfully to the synthesis of two natural products, rubranine and deoxybruceol. [ABSTRACT FROM AUTHOR]

Isoindole derivatives containing an azetidin-2-one moiety were prepared from phthalic anhydride by an approach that involves a [2p+2p] cycloaddition of an imine to a novel ketene generated in situ, and an electrocyclic reaction of a zwitterionic intermediate. The reactions were highly stereoselective and trans-β-lactams were obtained as the sole observed products. [ABSTRACT FROM AUTHOR]

A tetrabutylammonium bromide catalyzed trifluoromethylation/cyclization reaction of o-aralkynylaryl aldehydes with trimethyl(trifluoromethyl)silane and cesium fluoride has been developed. A variety of 1-alkylidene-3-(trifluoromethyl)phthalans were prepared in moderate to excellent yields by tandem nucleophilic addition and cyclization. [ABSTRACT FROM AUTHOR]

Tetramethylcyclobutadiene-AlCl3 complex reacted with bisalkynes possessing phenylene and biphenylene spacer giving rise to mono- and bis-Dewar benzenes. The rearrangement of the bis-Dewar benzene derivatives under thermal conditions (150 ˚C) yielded the corresponding linear ter- and quaterphenyl compounds possessing substituted terminal benzene rings. A mixture of an alkynylbiphenyl and a terphenyl was also obtained by the reaction of tetramethylzirconacyclopentadiene with bisalkynylbenzene in 13% combined yield. [ABSTRACT FROM AUTHOR]

Tetramethylcyclobutadiene-AlCl3 complex reacted with bisalkynes possessing phenylene and biphenylene spacer giving rise to mono- and bis-Dewar benzenes. The rearrangement of the bis- Dewar benzene derivatives under thermal conditions (150 °C) yielded the corresponding linear ter- and quaterphenyl compounds possessing substituted terminal benzene rings. A mixture of an alkynylbiphenyl and a terphenyl was also obtained by the reaction of tetramethylzirconacyclopentadiene with bisalkynylbenzene in 13% combined yield. [ABSTRACT FROM AUTHOR]

A thermally induced reaction cascade including an electrocyclic rearrangement, two Diels-Alder reactions and a 1,4-elimination from a simple cyclobutene carbonate can explain the synthesis of a complex tricyclo[3.2.1.02,7]oct-3-ene core structure. [ABSTRACT FROM AUTHOR]