Diradical reaction mechanisms in [3 + 2]-cycloadditions of hetaryl thioketones with alkyl- or trimethylsilyl-substituted diazomethanes

• Grzegorz Mlostoń,
• Paulina Pipiak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2016, 12, 716–724, doi:10.3762/bjoc.12.71

• the University of Łódź. Applied reagents such as 2-diazopropane (7a) and diazoethane (7b) were prepared by known methods according to the literature protocols [31][32]. Thiobenzophenone (1a), fluorene-9-thione (thiofluorenone, 1b), symmetrical dihetaryl thioketones 1d,e, and nonsymmetrical aryl

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• been employed in view to reduce these undesirable effects, e.g., the synthesis of copolymers [14][15][16][17], block copolymers [18], the introduction of donor (D) and acceptor (A) moieties [19][20][21], or bulky substituents at the C-9 position of the fluorene units [22][23][24], incorporating PF

• [2,7-(9,9-dioctylfluorene)-alt-2,7-fluorene/TM-βCD)] (3·TM-βCD) and poly[2,7-(9,9-dioctylfluorene)-alt-2,7-fluorene/TM-γCD)] (3·TM-γCD) polyrotaxanes have been synthesized. Thus, 3·TM-βCD and 3·TM-γCD have been obtained through the Suzuki cross-coupling reaction of 2,7-dibromofluorene (1) encapsulated

• analysis (TGA). All copolymers showed only glass-transitions (Tg) and not any exothermal crystallization peak characteristic of polymers containing 9,9-dioctyl-2,7-fluorene units (PFO) [49], Figure 2. The non-rotaxane copolymer 3 has a Tg at 88 °C. The Tg value increases for 3·TM-γCD and 3·TM-βCD to 96 °C

Efficient synthesis of π-conjugated molecules incorporating fluorinated phenylene units through palladium-catalyzed iterative C(sp²)–H bond arylations

• Fatiha Abdelmalek,
• Fazia Derridj,
• Safia Djebbar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2015, 11, 2012–2020, doi:10.3762/bjoc.11.218

• ][34], this technology has been increasingly employed for the synthesis of fluorinated π-conjugated materials, but this strategy was limited to the synthesis of end-caped fluorene oligomers [35][36][37][38][39][40][41][42][43]. Organic molecules containing polyfluoroaryl groups have been also

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• product (toluene, 38). Diphenylacetic acid yielded tetraphenylethane in a near-quantitative yield but in contrast, the related 9H-fluorene-9-carboxylic acid produced the reduced alkane (9H-fluorene) as the major product. Incorporation of substituents on the phenyl ring proved a success; arylacetic acids

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• 9H-fluorene (298) and propargyl bromide, which on further treatment with 1,4-diazidobutane (300) and xylyl azides 302a–c in the presence of CuSO4·5H2O and sodium ascorbate in THF/water (1:1) gave the corresponding macrocycles (301, 42%) and (303a–c, 60–70% yield, Scheme 52). Murphy and Leyden [186

Palladium-catalyzed 2,5-diheteroarylation of 2,5-dibromothiophene derivatives

• Fatma Belkessam,
• Aidene Mohand,
• Jean-François Soulé,
• Abdelhamid Elias and
• Henri Doucet

Beilstein J. Org. Chem. 2014, 10, 2912–2919, doi:10.3762/bjoc.10.309

• et al. [38]. A fluorescent π-conjugate thiophene derivative bearing spiro[fluorene-9,4’-[4H]indeno[1,2-b]furan] substituents at C2 and C5 has been prepared in 46% yield by this reaction using Pd(OAc)2 (5 mol %) associated to PPh3 (10 mol %) as catalytic system [39]. A pyrrole derivative was coupled

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• other irreversible (Epa > 1.2 V). The potential of the former is too low to be related to the oxidation of the arms [34] or an isolated BODIPY unit [35]. It is probably due to the oxidation of the fluorene–BODIPY–fluorene structural unit, with the fluorene arms attached in the α- and β-positions for Y

• V). Due to conjugation between the BODIPY core and the arms in its α-position, the electronic structure of Y-B1 provides stabilisation of the negative doped states owing to partial delocalisation of charge/spin density over the unit α-fluorene–BODIPY–α-fluorene. This can be seen from DFT

• calculations for this structure (vide infra) which show slight expansion of the LUMO from the core to the arm. The increase in reduction potential with increasing length of the arm could be explained by the lower electron density exerted by one fluorene in each arm, as opposed to the oligofluorenes in the

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• ]. Synthesis of 2,7-dibromo-9,9-(dicyanomethylene)fluorene (1): 2,7-dibromo-9,9-(dicyanomethylene)fluorene was prepared by a condensation reaction between 2,7-dibromofluoren-9-one with malononitrile at 110 °C in DMSO according to a literature method [13][33][34]. Synthesis of bis(4-bromophenyl)(4-methylphenyl

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• , Eugene, Oregon 97403, USA Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA 10.3762/bjoc.10.219 Abstract We report a new synthetic route to 5,11-disubstituted indeno[1,2-b]fluorene-6,12-diones that is amenable to larger scale reactions, allowing for the preparation of

• gram amounts of material. With this new methodology, we explored the effects on crystal packing morphology for the indeno[1,2-b]fluorene-6,12-diones by varying the substituents on the silylethynyl groups. Keywords: crystal packing; electron accepting; indenofluorenes; organic electronics; polycyclic

• . Our laboratory has been exploring a new class of PCHs based on the five structural isomers of indenofluorene [9]. In particular, the indeno[1,2-b]fluorene (IF, 1, Figure 1) skeleton is similar to linear oligoacenes, with the notable exception that the molecule contains two five-membered carbocycles

First synthesis of meso-substituted pyrrolo[1,2-a]quinoxalinoporphyrins

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2014, 10, 808–813, doi:10.3762/bjoc.10.76

• ) porphyrins (5, 6 and Zn–TPP) are shown in Figure 1a,b. Besides the Soret and Q bands in porphyrins 4g, 4h, 5 and 6, an additional absorption peak originates at 280 and 320 nm due to the presence of pyrene and fluorene units, respectively. Thus, the electronic absorption spectra of these compounds

• demonstrated the features of both porphyrin and pyrene or fluorene subunits and suggest that there is no significant interaction between the attached chromophore and the porphyrin ring in the ground state. The fluorescence spectra of porphyrins 4f, 4g, 4h, 5 and 6 were recorded in CHCl3 at the excitation

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• , obtained in the presence of a simple dehydrating agent, were limited to the use of simple aldehydes, amines and α-acidic α,α-disubstituted isocyanides such as methyl isocyano(phenyl)acetate and 9-isocyano-9H-fluorene [89]. The scope of these reactions could be extended to isocyanides with other

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• ′,2′-c]fluorene, also known as truxene (Figure 1), is a heptacyclic polyarene with C3 symmetry that can be envisaged as three fluorenes that are superimposed through a common central benzene ring [2][3]. Truxene has been used as a starting compound, or a core unit, for larger star-shaped polyarenes

• by using the RI-J approximation [23]. The hexyl chains on the fluorene units were shortened to methyl groups in the model in order to decrease the computational cost of the simulation. The main structural difference observed is the degree of twisting between the fluorene and thiophene in the two

• . HOMO−1 (bottom, left), HOMO (bottom, right), LUMO (top, left) and LUMO+1 (top, right) of T1-4FTh. Synthesis of the thiophene-fluorene arm for the 3-isomer. Synthesis of the thiophene-fluorene arm for the 4-isomer. Coupling of arms to the truxene core. Synthesis of T4-4FTh. Optical data for TX-xFTh and

Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

• Aurica Farcas,
• Ana-Maria Resmerita,
• Andreea Stefanache,
• Mihaela Balan and
• Valeria Harabagiu

Beilstein J. Org. Chem. 2012, 8, 1505–1514, doi:10.3762/bjoc.8.170

• bulkier silylated groups, affecting the ability of the diborate groups from the DOF molecule to partially penetrate the PS-βCD cavity. Keywords: alternating fluorene-bithiophene copolymer; cyclodextrins; interlocked molecules; macrocycles; persilylated β-cyclodextrin; polyrotaxanes; Introduction Organic

• wide emission band during operation [8]. Taking into account the relevant photophysical properties of these organic compounds, new synthetic approaches were developed. Copolymerization of fluorene with thiophene, bithiophene or other aromatic comonomers is an alternative method for tuning the optical

• photophysical properties of PFs by using persilylated γ-CD as a new host molecule [33]. Inclusion of bithiophene into persilylated β-cyclodextrin, randomly methylated β-cyclodextrin, or chemically modified CD derivatives, followed by copolymerization with fluorene monomers results in significant changes in the

Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

• Sergio Pascual,
• Christophe Bour,
• Paula de Mendoza and
• Antonio M. Echavarren

Beilstein J. Org. Chem. 2011, 7, 1520–1525, doi:10.3762/bjoc.7.178

• pathway. The cyclization of 9-(3-phenylprop-2-ynyl)-9H-fluorene (7a) to form 3-phenylfluoranthene (8a) [59] was also examined by using catalysts 5, 6, and GaCl3 (Table 2). Since the initial gold(I)-catalyzed reaction provided a mixture of 3-phenyl-1,10b-dihydrofluoranthene, 3-phenyl-1,2,3,10b

• (Table 2, entries 11 and 12). The reaction of 3a with Pd(OAc)2 as catalyst proceeded differently to give known (E)-9-(3-phenylallylidene)-9H-fluorene (9) [60], presumably via the formation of the corresponding allene as an intermediate (Scheme 2). Substrates 7b–j, prepared by alkylation of fluorenyl

• lithium with the corresponding propargyl bromide or by Sonogashira couplings of 9-(prop-2-ynyl)-9H-fluorene [61], were cyclized by using gold(I) complex 6 or GaCl3 as the catalyst (Table 3). Although both catalysts could be used for the synthesis of 3-arylfluoranthenes 8b–h, better yields were obtained

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• Yu-Hsuan Wang Joshua F. Bailey Jeffrey L. Petersen Kung K. Wang C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA 10.3762/bjoc.7.58 Abstract 5-(2-Methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene were

• to form 5-phenyl-11H-benzo[b]fluorene (3a) in a single operation (Scheme 1) [5]. It is interesting to note that the newly formed benzo[b]fluorenyl moiety in 3a could also be regarded as a 1-arylnaphthyl derivative with three additional substituents at the 2, 3, and 4 positions. The reaction is not

• -ethynyl-2-(methoxymethyl)benzene (4b). On exposure to potassium tert-butoxide in refluxing toluene for five hours, 9a was transformed to 5-(2-methoxyphenyl)-11H-benzo[b]fluorene 13a along with a small amount (ca. 2%) of 14a in a single operation. Presumably, the cascade sequence involved an initial 1,3

SbCl₃-catalyzed one-pot synthesis of 4,4′-diaminotriarylmethanes under solvent-free conditions: Synthesis, characterization, and DFT studies

• Ghasem Rezanejade Bardajee

Beilstein J. Org. Chem. 2011, 7, 135–144, doi:10.3762/bjoc.7.19

• ) which highlights the application of SbCl3 as useful catalyst in this methodology. Furthermore, the application range of the reaction was expanded to fused aromatic rings such as 9H-fluorene and anthracene: 9H-Fluorene-2-carbaldehyde and anthracene-9-carbaldehyde react with N,N-dimethylaniline under the

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• ]. The polymers consisted of dialkylated DPP units and carbazole, triphenylamine, benzo[2,1,3]thiadiazole, anthracene, or fluorene units in alternating fashion. They were prepared via Suzuki coupling, from the DPP monomers M-1 or DPP-3,6-diphenyl(4,4´-bis(pinacolato)boron ester. A number of readily

• a brightness at 20 V of 50 cd m−2 without much optimization. The maximum emission was at 600 nm, the turn-on voltage was 3.5 V. Cao et al. [33] prepared DPP-fluorene copolymers with a DPP content of between 0.1 and 50%. It was found that absorption and emission spectra, both in solution and thin

• content, the EQE was lowered to 0.14%, and the brightness to 127 cd m−2, similar to the results reported by Zhu et al. [31]. Cao et al. [34] also studied DPP-fluorene alternating copolymers with the fluorene unit being attached to the m-position of the phenyl groups in DPP (in contrast to the usual p

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• these methods have been applied to building blocks with additional substituents including functional groups as well as to other aromatic building blocks, such as biphenyl [33], bipyridine [36][42], thiophene [36][43][44], fluorene [45], and triptycene [46], and other shapes, e.g. starlike compounds [2