Cathodic hydrodimerization of nitroolefins

• Michael Weßling and
• Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

• is the pyrrole derivative 22, in the air its light colour deepens quickly to brown. The electrolyses proceed uniformly. The current reaches after a short induction period (1–3 min) depending on the substrate a maximal current of 250–450 mA, which then decreases exponentially to zero. The dichloro

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• functionalised MPTTF and BPTTF species. Firstly, the large-scale preparation of the precursor species N-tosyl-(1,3)-dithiolo[4,5-c]pyrrole-2-one (6) is described, as well as the synthesis of the analogue N-tosyl-4,6-dimethyl-(1,3)-dithiolo[4,5-c]pyrrole-2-one (7). Thereafter, we show how 6 and 7 can be used to

• and Becher to develop pyrrole-annelated TTF derivatives: monopyrrolotetrathiafulvalenes (MPTTFs, 4) and bispyrrolotetrathiafulvalenes (BPTTFs, 5) (Figure 2) [4][25]. The presence of either one or two fused pyrrole rings, respectively, eliminates cis–trans isomerism whilst still allowing for further

• in the synthesis of functionalised MPTTFs and BPTTFs. We report a more convenient and larger scale (>20 g) synthesis of the key building block N-tosyl-(1,3)-dithiolo[4,5-c]pyrrole-2-one (6), than that previously published [25], in addition to the synthesis of its dimethylated analogue, N-tosyl-4,6

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• compounds which can be applied in organic optoelectronic materials. Indeed, we have recently reported the synthesis of novel push–pull dyes IK-1,2 based on the thieno[2,3-b]indole ring system, as a donating part of dye-sensitized solar cells [8] (Figure 1). It should be noted that thieno[2,3-b]pyrrole and

• thieno[3,2-b]pyrrole ring systems have been incorporated in the structures of various fused polycyclic compounds (heteroacenes), which have been used as efficient hole-transport materials for organic light emitting diodes (OLEDs) or field effect transistors (OFETs) [9][10][11][12][13][14][15]. Taking

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• hemiacetals after cascade reactions. Keywords: alkyne cyclization; gold-catalyzed reaction; indolo-oxazin-1-one; marine natural products; pyrrolo-oxazin-1-one; Introduction Pyrrole-containing heterocycles are widely distributed within a large number of natural products and biologically active molecules [1

• ]. These compounds possess a wide range of biological and pharmacological activities [2][3][4][5]. The oxazinone moiety is also frequently found in compounds displaying biological activities [6][7]. Pyrrolo-oxazinone structures with an oxazinone ring fused to a pyrrole are found in marine natural products

• substituted core structure 6 (Figure 2), which was generated by treatment of methyl 2-pyrrole-carboxylate with chloroacetone [2][27][28][29][30]. This core structure is also a very important intermediate for the synthesis of pyrrolo-pyrazinones as well as for pyrrolo-pyrazines [31]. Recently, Wang et al

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• approaches for the preparation of N-arylated MPTTF derivatives 4 have been reported (Scheme 1). In the first procedure [14][15][16], the aryl substituent is incorporated during the initial synthetic steps to form a N-aryl-1,3-dithiolo[4,5-c]pyrrole-2-thione 5, which is then coupled to 1,3-dithiole-2-thione 6

• planarity. Angles between the least-square planes, defined by the heavy atoms of the aromatic ring and neighbouring pyrrole ring do not exceed 17.3° (in 4e, see Table 2), ensuring good conjugation between the MPTTF and aromatic moieties. Boat-type deviations of the TTF groups (folding along the S–S vectors

• aromatic starting material and then purified by flash chromatography on silica gel to afford pure N-arylated MPTTFs. Preparation and characterization of 2-[4,5-bis(propylthio)-1,3-dithiol-2-ylidene]-5-(4-methoxyphenyl)-5H-1,3-dithiolo[4,5-c]pyrrole (4a) and 2-[1,3-dithiol-2-ylidene]-5-(4-methoxyphenyl)-5H

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• for symmetrical [76] A4 and trans-disubstituted [77] A2B2 meso-functionalized porphyrins. The tetrabrominated core 1 was synthesized from aldehyde 3 and pyrrole (4) to form the free base porphyrin 5, which is subsequently converted into its zinc complex 1. On the other hand the difunctional core 2 was

• using 20 and pyrrole (4) following the Lindsey protocol [77] for A4 porphyrins gives the desired tetravalent porphyrin host as the free base 21, which is subsequently converted into the desired product C4 by metalation using zinc(II) acetate. Host C2 was synthesized according to the above-mentioned

• ) and respective experimental and calculated isotopic patterns of the desired [2]- or [3]pseudorotaxanes (right hand side): a) 1:1 mixture of A2 and C2, b) 2:1 mixture of A2 and C4, c) 1:1 mixture of A4 and C4, d) 1:2 mixture of A4 and C2. Overview of the synthesis of the guests A2 and A4. a) Pyrrole (4

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• state. In addition, they can be easily derivatized [31][32][33][34][35][36][37]. If the optical properties of BODIPY are very sensitive to modification of the pyrrole core [38][39], they are less sensitive to the substitution of the central pseudo meso position [40][41]. Additionally, the fluorine

Novel stereocontrolled syntheses of tashiromine and epitashiromine

• Loránd Kiss,
• Enikő Forró and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2015, 11, 596–603, doi:10.3762/bjoc.11.66

• 1,3-dipolar cycloaddition and reduction [34] (Figure 3). (−)-Tashiromine has been accessed through the ring closure of difunctionalized acyclic chiral sulfonamide-based β-amino acids [35], the cyclization of pyrrole derivatives with a chiral side-chain [36], or the enantioselective arylation of

• pyrrole, followed by saturation [37]. The transformation of chiral functionalized pyrrole or pyrrolidine derivatives has served as the basis of the construction of (−)-epitashiromine [38][39] (Figure 4). The oxidative functionalization of cyclic β-amino acid derivatives has been reported to be a

Functionalized branched EDOT-terthiophene copolymer films by electropolymerization and post-polymerization “click”-reactions

• Miriam Goll,
• Adrian Ruff,
• Erna Muks,
• Felix Goerigk,
• Beatrice Omiecienski,
• Ines Ruff,
• Rafael C. González-Cano,
• Juan T. Lopez Navarrete,
• M. Carmen Ruiz Delgado and
• Sabine Ludwigs

Beilstein J. Org. Chem. 2015, 11, 335–347, doi:10.3762/bjoc.11.39

• the electropolymerization can be regarded as a crosslinking step [17][18]. Electropolymerization of monomer mixtures is another powerful tool to modify material properties. Among a variety of monomer mixtures including pyrrole and thiophene [19][20], 2,2’-bithiophene and pyrrole [21][22] and

• [28] or the modification of the surface polarity heading for bio-compatible electrodes [29]. The direct electropolymerization of ionically modified monomers was for example carried out by Reynolds et al. for sulfonic acid functionalized pyrrole [30][31]. The groups of Heeger et al. [32][33][34

• modified bithiophene followed by bipyrrole monomers [38]. In some cases the direct polymerization of ionically modified monomers remains problematic: this was for example reported in the case of sulfonic acid modified pyrrole, where film deposition was only possible when a copolymerization with pristine

2-(1-Hydroxypropyn-2-yl)-1-vinylpyrroles: the first successful Favorsky ethynylation of pyrrolecarbaldehydes

• A. V. Ivanov,
• V. S. Shcherbakova,
• I. A. Ushakov,
• L. N. Sobenina,
• O. V. Petrova,
• A. I. Mikhaleva and
• B. A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 228–232, doi:10.3762/bjoc.11.25

• modified conditions of the Favorsky reaction has been implemented to pave an expedient route to important biomolecules containing a pyrrole ring. Keywords: acetylene; ethynylation; Favorsky reaction; 1-vinylpyrrole-2-carbaldehyde; Introduction Functionalized pyrroles bearing a terminal acetylenic moiety

• spasm, brain ischemia, cerebral and myocardial infarction, nephritis, immune diseases, and Crohn’s disease [3]. 2-(1-Hydroxypropyn-2-yl)pyrroles have also been employed for the annulation of a cyclopentanone ring onto a pyrrole to form fused bicycles which then have abundant use as synthetic

• synthesized exclusively by the addition of ethynylmagnesium halides (Iotsich complexes [6]) to pyrrole-2-carbaldehydes [4][7][8]. Astonishingly, the classic Favorsky ethynylation of pyrrole aldehydes with alkynes in the presence of KOH proves to be absolutely invalid. In fact, our attempt to ethynylate

Efficient deprotection of F-BODIPY derivatives: removal of BF₂ using Brønsted acids

• Mingfeng Yu,
• Joseph K.-H. Wong,
• Cyril Tang,
• Peter Turner,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 37–41, doi:10.3762/bjoc.11.6

• derivatives incorporating fluorescent dyes for sensing applications [22][23][24][25]. Looking to extend these systems to incorporate an F-BODIPY motif, we have synthesized the Boc-protected triazolyl-cyclam/F-BODIPY derivatives 3 and 4 from 2,4-dimethyl-1H-pyrrole (5), 4-nitrobenzaldehyde (6, Scheme 2A) and 4

• and conditions: (a) (i) 2,4-dimethyl-1H-pyrrole (5), TFA, DCM, rt, overnight; (ii) DDQ, rt, 2 h; (iii) Et3N, BF3·OEt2, rt, overnight, 27%; (b) NH2NH2·H2O, 10% Pd/C, EtOH, reflux, 2 h, 90%; (c) (i) 1 M HCl (aq), CH3OH, NaNO2, H2O, 0 °C, 1 h; (ii) NaN3, H2O, rt, 2 h, 71%; (d) propargyl-tri-Boc cyclam 12

• , CuSO4·5H2O, sodium ascorbate, THF/H2O (7:3), 50 °C, 12 h, 100%; (e) trimethylsilylacetylene, CuI, Pd(PPh3)4, Et3N, THF, rt, overnight, 100%; (f) K2CO3, CH3OH, rt, overnight, 71%; (g) (i) 2,4-dimethyl-1H-pyrrole (5), TFA, DCM, rt, overnight; (ii) DDQ, rt, 2 h; (iii) Et3N, BF3·OEt2, rt, overnight, 24%; (h

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• modulation of its amino groups at 3 and 8 positions of the phenanthridine ring [52][53]. Systematic changing of the ethidium bromide exocyclic amines into guanidine, pyrrole, urea, and various substituted ureas revealed importance of electron-donor properties of substituents at the 3- and 8-position of the

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

• )pyrrole (33) in 61% yield (Scheme 6, bottom). Finally, as 4,7-diarylbenzothiadiazoles also display important physical properties [45], we applied our procedure to 4,7-dibromobenzothiadiazole which is commercially available (Scheme 7). In all cases, the desired 4,7-diarylbenzothiadiazoles 34–38 were

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

• pyrrole unit as well. It is known that attaching aromatic units to the β-positions of BODIPY increase the Stokes shift due to more pronounced structural relaxation of the excited state [29]. Therefore, incorporating the BODIPY unit as the core could improve the separation between absorption and emission

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• ], and 7 [47] were prepared according to the literature. 10,10'-(5',5'''-(2,5-Bis(2-octyldodecyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo[3,4-c]pyrrole-1,4-diyl)bis([2,2'-bithiophene]-5',5-diyl))bis(2,8-diethyl-5,5-difluoro-1,3,7,9-tetramethyl-5H-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-4-ium-5-uide) (9

• : 165–167 °C. 10,10'-(5'',5'''''-(2,5-Bis(2-octyldodecyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo[3,4-c]pyrrole-1,4-diyl)bis([2,2':5',2''-terthiophene]-5'',5-diyl))bis(2,8-diethyl-5,5-difluoro-1,3,7,9-tetramethyl-5H-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-4-ium-5-uide) (10): BODIPY 7 (278 mg, 0.5 mmol

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• the nine-membered ring led to tricyclic compound 45. The pyrrole ring of 45 was formed by intramolecular condensation of cinnamyl amide 46, which is prepared via union of quaternary piperidinone 47 and cinnamyl electrophile 48. We envisioned that our allylic alkylation of lactam enolates would furnish

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• general scheme for the thermal degradation of RF has been proposed by Mastowska and Malicka [151] which is based on TG, DTG and DTA analysis. The thermal degradation of RF initiates with its ribityl side chain by losing three molecules of water, followed by degradation to give a pyrrole ring, and

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• (+/−)-6-carba-analog of (+)-hydantocidin, compound (+/−)-103 was devoided of herbicidal activity at 1000 ppm concentration. 9. Miscellaneous reactions Dondas et al. reported the synthesis of a derivative of compound 107 bearing the pyrrolo[3,4-c]pyrrole skeleton at the furanose C-4' position from uracil

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• [2] such as methyl pyrrole-2-carboxylate, emitted by Stackebrandtia nassauensis, or 2-acetylpyrrole from Saccharopolyspora erythraea, volatile alkaloids are rarely produced by actinomycetes. We became interested in the strain Streptomyces sp. FORM5 to elucidate whether volatile formation is linked to

Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

• Jens Schmidt,
• Zeinab Khalil,
• Robert J. Capon and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2014, 10, 1228–1232, doi:10.3762/bjoc.10.121

• sequence, which incorporates a regioselective pyrrole alkylation, an electrophilic aromatic nitration and a regio- and stereoselective Corey–Noe–Lin dihydroxylation [18], has previously been described (in the total synthesis of heronapyrrole C) [3]. The procedure of Shi et al. [19][20][21] was then used to

Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

• Zong Guan,
• Jan C. Namyslo,
• Martin H. H. Drafz,
• Martin Nieger and
• Andreas Schmidt

Beilstein J. Org. Chem. 2014, 10, 832–840, doi:10.3762/bjoc.10.79

• observable in NMR spectra at standard temperature conditions. The spiro compound 14c crystallized from a saturated solution in n-hexane so that we were able to perform a single crystal X-ray analysis. The compound crystallized monoclinic. As expected, neither the pyrrole ring nor the pyrazole ring is planar

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• -coupling reaction in excellent yields [26]. The non-symmetric 4,6’-disubstituted bipyridine 10 was obtained in good yield from a Negishi cross-coupling of 6 and 7 [27]. Cleavage of the pyrrole protecting groups of 8–10 with hydroxylamine provided the corresponding diamines 11–13 [26] in satisfying to

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

• temperature (80 °C), but under an argon atmosphere [16]. An interesting Ag-promoted cascade synthesis of pyrrole-2-carboxyaldehydes involving an A3-coupling followed by an unusual imidazole ring opening, was reported by Liu in 2011 [17]. The authors found that propargylamines derived from the AgBF4-catalyzed

• coupling of imidazole-4-carboxyaldehydes 3, differently substituted alkynes and secondary amines were susceptible to a subsequent in situ transformation to give 3,5-disubstituted pyrrole-2-carboxaldehydes 4 in moderate to good yields in addition to variable amounts of 5-substituted-5H-pyrrolo[1,2-c

• was proven to be necessary in the reaction system. A series of experiments with 1-, 2- or 5-formylimidazoles and selected control reactions with the isolated propargylamine intermediate, partly in the presence of D2O or H218O, were helpful to clarify the mechanism of the formation of pyrrole-2

Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones

• Murat Kucukdisli,
• Dorota Ferenc,
• Marcel Heinz,
• Christine Wiebe and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 466–470, doi:10.3762/bjoc.10.44

• .10.44 Abstract The cyclocondensation of enones with aminoacetonitrile furnishes 3,4-dihydro-2H-pyrrole-2-carbonitriles which can be readily converted to 2,4-disubstituted pyrroles by microwave-induced dehydrocyanation. Alternatively, oxidation of the intermediates produces 3,5-disubstituted pyrrole-2

• closure to furnish 3,4-dihydro-2H-pyrrole-2-carbonitriles 6 after reprotonation [36]. If the products are devoid of an additional substituent in 2-position, the cyclocondensation can be simply effected by refluxing a mixture of the enone 1 and aminoacetonitrile hydrochloride (2) in pyridine. The base

• ) under acidic conditions. Several strong and weak acids were screened at temperatures ranging from 0–150 °C. The formation of pyrrole 7a was observed in acetic acid under microwave heating but many byproducts were formed under these conditions, presumably due to oligo- and polymerization of the product

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• allows their application in the synthesis of important heterocycles such as indole [28], dihydropyridine [29], quinoline [30], pyrrole [31] and pyridinone [32]. Furthermore, they can take part in one-pot multicomponent reactions with both nucleophilic and electrophilic reactants, leading to a fast access