Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

• Mikhail Yu. Ievlev,
• Oleg V. Ershov,
• Mikhail Yu. Belikov,
• Angelina G. Milovidova,
• Viktor A. Tafeenko and
• Oleg E. Nasakin

Beilstein J. Org. Chem. 2016, 12, 2093–2098, doi:10.3762/bjoc.12.198

• ). Previously we reported about several ways of heterocyclization thereof [15][16][17][18][19][20][21][22][23], including the formation of pyran derivatives [20][21][22][23][24]. Our recent work should be noted individually, we were able to prepare various functionalized pyrano[3,4-c]pyrrole derivatives via

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• structure is distorted tetrahedral with favorable π–π stacking distances between the proximal phenyl and pyrrole rings of the two separate ligands (Figure 10a and 10b). The distance between centroids is 3.56 Å for Zn(L2)2, compared to 3.63 Å for Zn(ADP)2 [38]. The shorter distance found for Zn(L2)2 suggests

• a stronger interaction between the proximal phenyl and pyrrole rings than in Zn(ADP)2. Unfortunately, it cannot be determined whether the addition of fluorine or phenylacetylene contributed to the shorter π–π stacking distances without a crystal structure for Zn(WS3)2. Intermolecular favorable π–π

• distorted tetrahedral shape; b) Shows the π-stacking between the proximal phenyl group of one ligand and a pyrrole ring of the opposite ligand. Generic synthetic scheme for fluorinated free ligands, where L# corresponds to the desired ligand number. For instance, L3-ADP and L3-ADPI2 would lead to the

Synthesis of pyrrolo[2,1-f][1,2,4]triazin-4(3H)-ones: Rearrangement of pyrrolo[1,2-d][1,3,4]oxadiazines and regioselective intramolecular cyclization of 1,2-biscarbamoyl-substituted 1H-pyrroles

• Kkonnip Son and
• Seong Jun Park

Beilstein J. Org. Chem. 2016, 12, 1780–1787, doi:10.3762/bjoc.12.168

• of 3-chloro-1H-pyrrole-2-carboxylic acid (13) using the Vilsmeier reagent [9], followed by further amination to produce 1H-pyrrole-2-carboxamide 14 in good to excellent yield [9]. A reaction mixture of 14 with NaOH, NH4Cl, and NaClO led to the formation of the N-aminopyrrole 15 [11]. The addition of

• the NH2+ to the nitrogen of pyrrole 14 by using the NaOH/NH4Cl/NaClO system [11] can be considered as a more practical method than others, such as those that use NH2Cl and HOSA [19]. In contrast to other substituents, 2-fluorophenyl and 4-cyanophenyl groups caused low yields (15b: 15%, 15f: 31%). The

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• as the result of imine oxidation and aryl migration. On the other hand, electron-withdrawing substituents on the aryl group (Ar) promote the formation of amides 119d–f as result of hydride migration. The sterically hindered and fully substituted pyrrole 120 underwent a Baeyer–Villiger reaction to

• synthesis of various heterocyclic systems, such as furan, thiophene, and pyrrole derivatives. The reaction of unsymmetrical epoxy dioxanes 290a–d with triethylamine is accompanied by the 1,2-dioxane-ring opening to form 4-hydroxy-2,3-epoxy ketones 291a–d in high yields. The base catalysis involves the

Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

• Hideaki Komiyama,
• Chihaya Adachi and
• Takuma Yasuda

Beilstein J. Org. Chem. 2016, 12, 1459–1466, doi:10.3762/bjoc.12.142

• purification. 2,5,9,12-Tetrabromoanthra[1,2-b:4,3-b':5,6-b'':8,7-b''']tetrathiophene (1) [25], 2,5-bis(2-ethylhexyl)-3-(5-(4-hexylphenyl)thiophen-2-yl)-6-(5-(trimethylstannyl)thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (2) [30][33], (5,12-bis(2-ethylhexyl)anthra[1,2-b:4,3-b':5,6-b'':8,7-b

• ''']tetrathiophene-2,9-diyl)bis(trimethylstannane) (3) [24][27], and 3-(5-bromothiophen-2-yl)-2,5-bis(2-ethylhexyl)-6-(5-(4-hexylphenyl)thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (4) [30] were synthesized according to the reported procedures. Detailed synthetic schemes for these compounds are provided

3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic–organic hybrid perovskite solar cells

• Wei Li,
• Munechika Otsuka,
• Takehito Kato,
• Yang Wang,
• Takehiko Mori and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2016, 12, 1401–1409, doi:10.3762/bjoc.12.134

• -type semiconducting polymers, such as poly(3-hexylthiophene) (P3HT), and the state-of-the-art narrow band gap polymers, such as poly[2,5-bis(2-decyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-(E)-1,2-di(2,2’-bithiophen-5-yl)ethane (PDPPDBTE), were successfully applied to the HTM in the PSCs [11][12

Application of Cu(I)-catalyzed azide–alkyne cycloaddition for the design and synthesis of sequence specific probes targeting double-stranded DNA

• Svetlana V. Vasilyeva,
• Vyacheslav V. Filichev and
• Alexandre S. Boutorine

Beilstein J. Org. Chem. 2016, 12, 1348–1360, doi:10.3762/bjoc.12.128

• synthesis of conjugates of pyrrole–imidazole polyamide minor groove binders (MGB) with fluorophores and with triplex-forming oligonucleotides (TFOs). Diverse bifunctional linkers were synthesized and used for the insertion of terminal azides or alkynes into TFOs and MGBs. The formation of stable triple

• helices by TFO-MGB conjugates was evaluated by gel-shift experiments. The presence of MGB in these conjugates did not affect the binding parameters (affinity and triplex stability) of the parent TFOs. Keywords: binding affinity; click chemistry; Cu(I)-catalyzed azide–alkyne cycloaddition; pyrrole

• ]. Besides natural and engineered peptides or proteins, two synthetic substances are known to recognize and bind dsDNA in a sequence-specific manner: triplex-forming oligonucleotides (TFOs) [4][5] and pyrrole–imidazole polyamide minor groove binders (MGBs) [6][7]. TFOs recognize polypurine stretches in

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• reaction times may cause the decomposition of products in the presence of K2CO3. In 2014, Wang et al. designed the chiral tridentate Schiff-base/Cu complex (cat. 3) for the asymmetric Friedel–Crafts alkylation of pyrrole with isatins (route a, Scheme 5) [17]. For N-protected isatin substrates, the final

• state for the observed stereoselectivity. Pyrrole attacked the ketone from the Si face to generate (R)-3-pyrrolyl-3-hydroxyoxindoles. Very recently, Feng et al. revealed that the bifunctional guanidine (L3)/CuI catalyst can catalyze asymmetric alkynylation of isatins with terminal alkynes, affording

Marine-derived myxobacteria of the suborder Nannocystineae: An underexplored source of structurally intriguing and biologically active metabolites

• Antonio Dávila-Céspedes,
• Peter Hufendiek,
• Max Crüsemann,
• Till F. Schäberle and
• Gabriele M. König

Beilstein J. Org. Chem. 2016, 12, 969–984, doi:10.3762/bjoc.12.96

• Na a174 yielded a new class of halogenated pyrrole–oxazole compounds 14–18 (Figure 8). Pyrronazols A (14), A2 (15) and B (16), synthesized by Ari7, additionally include an α-pyrone moiety [48]. This is worth noting, since the non-cyclic alkyl moiety in the pyrronazols C1 (17) and C2 (18), found in

Iridium/N-heterocyclic carbene-catalyzed C–H borylation of arenes by diisopropylaminoborane

• Mamoru Tobisu,
• Takuya Igarashi and
• Naoto Chatani

Beilstein J. Org. Chem. 2016, 12, 654–661, doi:10.3762/bjoc.12.65

• instability of 11-B during isolation (Table 2, entry 8). Our protocol was able to borylate non-benzofused five-membered heteroarenes. Pyrrole 12 was much less reactive than indoles, and required neat conditions to obtain a modest yield of the borylated product 12-B (Table 2, entry 9). Thiophene (13) afforded

Effective in silico prediction of new oxazolidinone antibiotics: force field simulations of the antibiotic–ribosome complex supervised by experiment and electronic structure methods

• Jörg Grunenberg and
• Giuseppe Licari

Beilstein J. Org. Chem. 2016, 12, 415–428, doi:10.3762/bjoc.12.45

• (ΔΔEb +25.8 kJ/mol). Candidate 25 superimposes well with the original position of linezolid itself. The pyrrole ring interacts via a strong H-bond (1.79 Å) with the G2540 phosphate group making this guest comparable to linezolid in terms of its remarkable relative binding affinity of +1.3 kJ/mol. A

• small negative relative binding energy is finally observed for guest 26. The lowest energy minimum of the ribosomal complex with this guest shows that now the guest is bound upside down: the pyrrole NH group establishes an effective H-bond with the nucleobase U2620 located at the A-site entry border

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• approaches rely on the anellation of the pyrrole part to indene-based starting materials [30][31][32][33]. In this paper we discuss our experiences with the assembly of cyclopenta[f]indole and -indoline systems (A, Scheme 1). A bond between the indole 5-position (4a in the resulting tricycle) and the

Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

• Ming-Liang Zhang,
• Deng-Feng Yue,
• Zhen-Hua Wang,
• Yuan Luo,
• Xiao-Ying Xu,
• Xiao-Mei Zhang and
• Wei-Cheng Yuan

Beilstein J. Org. Chem. 2016, 12, 295–300, doi:10.3762/bjoc.12.31

• 100049, China 10.3762/bjoc.12.31 Abstract For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H

• -pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee). Keywords: asymmetric catalysis; bifunctional catalysts; Henry reaction; organocatalysis; 1H-pyrrole-2,3-diones; Introduction Asymmetric organocatalysis has been

• construction of the useful and versatile β-nitroalcohol scaffolds is still desirable. Pyrrole skeletons represent an important class of heterocycles and are frequently found in many biologically active molecules and natural products [27][28]. Particularly, 3-substituted-3-hydroxy-1H-pyrrol-2(3H)-one

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• : conjugation; heterocycles; hydroquinone; linker effect; pyrrole; Introduction Quinone–pyrrole dyads have attracted interest in various applications due to the possibility of modulating the electronic interaction between the two subunits, with porphyrin–quinone dyads being well-known examples [1][2][3

• different linkers between the pyrrole and hydroquinone subunits was designed [6]. Although it is known that N-protected pyrrole (Py) can be selectively functionalized at the β-position [7], we found the published procedures to be unsuitable for our purpose (vide infra). Therefore, we have developed improved

• procedures for the synthesis of quinone–pyrrole dyads with a variety of linkers between the two subunits. The target compounds thus consist of a pyrrole unit as well as a hydroquinone group (protected as dimethyl ether, i.e., dimethoxybenzene, DMB), connected by different linkers, resulting in varying

Biocatalysis for the application of CO₂ as a chemical feedstock

• Apostolos Alissandratos and
• Christopher J. Easton

Beilstein J. Org. Chem. 2015, 11, 2370–2387, doi:10.3762/bjoc.11.259

• drive the equilibrium toward carboxylation, such as high CO2 concentration. Successful examples include the carboxylation of phenol and hydroxystyrene derivatives including catechol [102], guaiacol [110], indole [101] and pyrrole [100] (Scheme 7). Isocitrate dehydrogenase As discussed above, as part of

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• synthesis of the tris-pyrrole macrocyclic pigment nonylprodigiosin [52]. A preliminary protonation of the tris-pyrrole followed by a RCM applied to 37 in the presence of the ruthenium catalyst 36 gave the macrocycle 38, which was then transformed into the saturated derivative 39 using the Wilkinson’s

• . Enyne ring-closing metathesis. Synthesis of (R)-(+)-muscopyridine using a RCM strategy. Synthesis of a tris-pyrrole macrocycle. Synthesis of a bicyclic imidazole. RCM using Schrock’s catalyst 44. Synthesis of 1,6-pyrido-diazocine 46 by using a RCM. Synthesis of fused pyrimido-azepines through RCM. RCM

The marine sponge Agelas citrina as a source of the new pyrrole–imidazole alkaloids citrinamines A–D and N-methylagelongine

• Christine Cychon,
• Ellen Lichte and
• Matthias Köck

Beilstein J. Org. Chem. 2015, 11, 2029–2037, doi:10.3762/bjoc.11.220

• Christine Cychon Ellen Lichte Matthias Kock Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany 10.3762/bjoc.11.220 Abstract The chemical investigation of the Caribbean sponge Agelas citrina revealed four new pyrrole–imidazole

• ) which consist of a pyridinium ring and an ester linkage instead of the aminoimidazole moiety and the common amide bond in PIAs. Keywords: Agelas citrina; marine sponges; mauritiamine; NMR; pyrrole–imidazole alkaloids; Introduction The family of pyrrole-imidazole alkaloids (PIAs) represents a

• double bonds of 2 were assigned to E configuration. Citrinamine B (2) is the 2,2´-didebromo derivative of nagelamide H (20). We could not observe a chiroptical effect for 2 as it was also described in the original work of 20. Our investigation on Agelas citrina yielded two additional pyrrole–imidazole

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

• -methyl-2-(2,3,4-trifluorophenyl)pyrrole (4) in 91% yield. It is important to note that 4 equiv of N-methylpyrrole were used in order to prevent the formation of the 2,5-diarylated pyrrole as a side product. Finally, both 2-pentylthiophene and benzothiophene were arylated in 76% and 82% yields

• , compound 13, was isolated in 35% yield. This lower yield might be explained by a slower oxidative addition rate to the palladium with this electron-rich aryl bromide. Next, we investigated the reactivity of 1-methyl-2-(2,3,4-trifluorophenyl)pyrrole (4) in a second direct arylation (Scheme 3). Using of PdCl

• (C3H5)(dppb) catalyst and KOAc as base in DMA, the C5 position of the pyrrole unit was arylated in 82% yield with a complete regioselectivity; whereas the C–H bond at C5’ position on the trifluorobenzene unit remained untouched. Moreover, under similar reaction conditions, using 4-bromobenzaldehyde or 4

Synthesis of quinoline-3-carboxylates by a Rh(II)-catalyzed cyclopropanation-ring expansion reaction of indoles with halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2015, 11, 1944–1949, doi:10.3762/bjoc.11.210

• reactions between pyrrole and chloromethylcarbene, and 2,3-dimethylindole and dichloromethylcarbene [20][21]. It was suggested that the quinoline ring system is formed by ring expension of a labile indoline cyclopropane intermediate. In analogy to the postulated literature pathway, we propose that the

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• may still limit dissociation of the (TTF+•)(PC61BM−•) bound pair. The surprising inertness of 14c towards electropolymerisation can be circumvented by replacing the thiophene units in the monomer terthiophene backbone with more electron-rich moieties, such as pyrrole and EDOT. Bisthienylpyrrolo-TTF

• of polymer 37. Polymer 47, synthesised by Stille polymerisation of 42 and 38, is an analogue of the polymer 39. A direct comparison between the obtained polymers with pyrroloTTF and thienoTTF units showed that the incorporation of an electron-rich pyrrole unit into the conjugated backbone leads to

• materials with a wider band gap as they are less stable to n-doping. The pyrrole unit lowers the oxidation potentials of the TTF moieties but the electrochemical dominance of the TTF is lost in the pyrrolo-TTF polymers. Another analogue of polymer 37 includes the 2,5-bis(2-octyldodecyl)-1,4-dioxopyrrolo[3,4

Fe(II)/Et₃N-Relay-catalyzed domino reaction of isoxazoles with imidazolium salts in the synthesis of methyl 4-imidazolylpyrrole-2-carboxylates, its ylide and betaine derivatives

• Ekaterina E. Galenko,
• Olesya A. Tomashenko,
• Alexander F. Khlebnikov,
• Mikhail S. Novikov and
• Taras L. Panikorovskii

Beilstein J. Org. Chem. 2015, 11, 1732–1740, doi:10.3762/bjoc.11.189

• reaction with sulfur affording the corresponding imidazolethiones under very mild conditions. Keywords: imidazole; isoxazole; NHC carbene; pyrrole-2-carboxylate; relay catalysis; Introduction Pyrrole-2-carboxyate and imidazole units are present in bioactive pyrrole-imidazole alkaloids and pyrrole

• complexes of pyrrole-2-carboxylic acid [23][24][25]. In some cases these complexes were prepared via dehydration of the corresponding proline complexes [25]. Substituted pyrrole-2-carboxylic acids as ligands of complexes are seldom used and are only exemplified by complexes of indole-2-carboxylic acid [26

• ][27] and coenzyme pyrroloquinoline quinone [28]. The synthesis of 4-imidazolylpyrrole-2-carboxylic acid derivatives usually involves the corresponding pyrrole with a functional group allowing the formation of a imidazole ring [8][9]. Recently we developed a new approach to 3-(1H-pyrrol-3-yl)-1H

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• species. Among radially expanded TTFs, Jeppesen, Becher, Nielsen, Sessler, and co-workers reported TTF-calix[4]pyrrole 3 as a valuable supramolecular receptor, and 3 easily incorporated 1,3,5-trinitrobenzene (TNB) in the cavity to form 4 (3:TNB = 1:2) (Figure 2) [41][42]. Furthermore, in the presence of

• halide ions, 3 formed the C60 complex 5, in which C60 was bound within the bowl-like cup of the TTF-calix[4]pyrrole core in a ball-and-socket binding mode [43]. Recently, the C3-symmetric compounds 6a,b incorporating three TTF residues were reported by Amabilino, Avarvari, and co-workers (Figure 3) [21

• 30 is estimated to be ca. 1000 times higher than that of the neutral fiber (before doping: σrt 3 × 10−6 S cm−1, after doping: σrt 3 × 10−3 S cm−1) [68]. Star-shaped pyrrole-fused TTF oligomers 38–43 were synthesized by nucleophilic aromatic substitution (SNAr) reactions of fluorinated benzenes with

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• using the DFT B3LYP method in order to rationalize the experimental results. Keywords: CH acidity; indoles; iodolysis; mixed lithium–zinc bases; pyrroles; Introduction Pyrrole occurs in very important natural products such as tetrapyrrolic (linear) bilirubinoids, and (cyclic) porphyrins and corrins

• pyrrole and indole substrates 1 and 2, the unsubstituted azoles were reacted with aryl and heteroaryl iodides under copper catalysis. As far as the derivatives 1a,b, 1d,e and 2a–e are concerned, the reactions were carried out by using 1.5 equiv of the azole, 0.2 equiv of copper, 2 equiv of caesium

• thiophene ring took place. After subsequent interception with iodine, N-(5-iodo-2-thienyl)pyrrole (3a) was isolated in nearly quantitative yield. Under the same reaction conditions, the corresponding indole substrate 2a was similarly converted into N-(5-iodo-2-thienyl)indole (4a) (Scheme 3). Starting from

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

A new and efficient procedure for the synthesis of hexahydropyrimidine-fused 1,4-naphthoquinones

• Marcelo Isidoro P. Reis,
• Vinícius R. Campos,
• Jackson A. L. C. Resende,
• Fernando C. Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2015, 11, 1235–1240, doi:10.3762/bjoc.11.137

• pyrrole-, furan- and thiophene-fused naphthoquinones [36]. For several years, our group has been interested in developing new synthetic methods for the preparation of heterocycle-fused 1,4-naphthoquinones or heterocycle-tethered 1,4-naphthoquinones. 1,3-Quinazolines are nitrogenated heterocycles that are