A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• unsymmetrically substituted diarylpyridines, difficult to access by other methods. Keywords: arylpyridines; cross coupling reaction; heteroaromatics; one-pot reaction; palladium catalyst; Introduction Nitrogen heterocycles are an important class of compounds widely present in agrochemical products [1][2] and

• display promising properties in asymmetric catalysis [19][20][21][22]. In our ongoing forensic chemistry programme directed toward the identification and synthesis of novel byproducts of illegally produced amphetamine analogues, we described the synthesis of several new nitrogen heterocycles. Among them

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

• piperazines. Review Direct α-C–H lithiation trapping Since the seminal discovery made by Beak and Lee [28][29], α-functionalization of N-Boc-protected nitrogen heterocycles via direct α-C–H lithiation trapping has been a straightforward and effective method to introduce various substituents on the α-carbon

• atoms [30][31]. Corresponding enantioselective versions have also been developed using chiral diamines as ligands to allow access to enantioenriched α-substituted nitrogen heterocycles. However, most of the success has been made in the territory of N-Boc-pyrrolidine [32][33] and N-Boc-piperidine [34][35

• -functionalization of N-Boc-protected saturated mono-nitrogen heterocycles via the lithiation trapping sequence using chiral diamines such as (−)-sparteine and (+)-sparteine surrogates as ligands have been made. However, the progress for the enantioselective α-functionalization of N-Boc-protected piperazines is

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• compounds even at 0 °C. It was also examined in more demanding systems such as conjugated dienes and polyenes. The catalyst is stable, storable and easy to purify. Keywords: chromane derivatives; metathesis catalyst; nitrogen heterocycles; olefin metathesis; Ru-carbene; Introduction Olefin metathesis is

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

• Antonia Di Mola,
• Maximilian Tiffner,
• Francesco Scorzelli,
• Laura Palombi,
• Rosanna Filosa,
• Paolo De Caprariis,
• Mario Waser and
• Antonio Massa

Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279

• particularly promising for large scale applications. Keywords: asymmetric synthesis; Belliotti (S)-PD 172938; heterocycles; isoindolinones cascade reactions; phase transfer catalysts; Introduction Among the nitrogen heterocycles, the isoindolinone ring system is a favored scaffold, owing to the wide range of

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• elimination of one of the chlorine atoms from the seven-membered ring, the acid-catalyzed reaction between methylene-active nitrogen heterocycles and о-chloranil occurs, depends on the conditions of its performance, with or without inclusion of a stage of dehydrochlorination and leads to 5,6,7-trichloro- or

• established. The interaction of o-chloranil with derivatives of 2-methylquinoline by method A or B proceeds more smoothly giving rise to the corresponding trichloro- and tetrachloro-1,3-tropolones with yields in the range of 60–85% [23]. Among the five-membered nitrogen heterocycles entered into the reaction

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• radicals to make transient imines [1][2][3]. In turn, onward reactions of the imines provide assorted products including ketones and nitrogen heterocycles [4][5][6][7][8][9][10]. Figure 1a shows a generic addition/elimination reaction of ene-sulfonamides along with example transformations in Figure 1b from

Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

• Marcel Mirel Popa,
• Emilian Georgescu,
• Mino R. Caira,
• Florentina Georgescu,
• Constantin Draghici,
• Raluca Stan,
• Calin Deleanu and
• Florea Dumitrascu

Beilstein J. Org. Chem. 2015, 11, 1079–1088, doi:10.3762/bjoc.11.121

• structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported. Keywords: indolizine; nitrogen heterocycles; N-ylide; 4-pyridylpyrimidine; pyrrolo[1,2-c]pyrimidine; Introduction Two heteroarenes linked through a single bond [1] proved to be versatile

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• ; nitrogen heterocycles; rearrangement; Introduction One of the foci of current organic synthesis is the exploration of new chemical space, with an emphasis on significant heterocyclic molecular diversity [1][2]. Direct applications of such advances in medicinal chemistry, chemical biology and nanochemistry

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

• structural fragment, since enaminones are versatile starting materials in organic synthesis and are notably important for the synthesis of nitrogen heterocycles [25][26][27]. In particular, β-enaminoketones are endowed with electrophilic and nucleophilic reaction centers and have a versatile reactivity that

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• being surrounded by three nitrogen heterocycles, but provide for CuAAC reactions that are much faster than with TBTA [80]. As neither copper(I) alkyne π-complexes nor acetylide complexes with this class of tris(heteroarylmethyl)amines as ancillary ligands have been characterized, mechanistic

Stereoselectively fluorinated N-heterocycles: a brief survey

• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2013, 9, 2696–2708, doi:10.3762/bjoc.9.306

• inspection of the medicinal chemistry literature will reveal two obvious themes in the structures of current drug candidates: the ubiquity of nitrogen heterocycles, and the popularity of organofluorine moieties. Therefore, it seems natural that a combination of these two features will offer rich

New syntheses of 5,6- and 7,8-diaminoquinolines

• Maroš Bella and
• Viktor Milata

Beilstein J. Org. Chem. 2013, 9, 2669–2674, doi:10.3762/bjoc.9.302

• . Dechlorination of 4-chloro-7,8-diaminoquinoline gave 7,8-diaminoquinoline hydrochloride which was successfully employed as starting material in the synthesis of condensed nitrogen heterocycles. Keywords: chlorination; deselenation; nitrogen heterocycles; o-diaminoquinolines; selenadiazoloquinolones

• 7,8-diaminoquinoline hydrochloride in the synthesis of nitrogen heterocycles is discussed in datail. Results and Discussion In the present approach, selenadiazoloquinolones 1 and 9 represent a masked form of the target o-diaminoquinolines where the o-phenylenediamine moiety is protected as the 2,1,3

• irreproducible due to this instability. Accordingly, it is far more convenient to employ hydrochloride 5 as the starting material in the subsequent reactions, whether isolated or prepared in situ. Next, hydrochloride 5 was applied as the substrate in the synthesis of nitrogen heterocycles (Scheme 2). The

Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

• Susanna Schmidbauer,
• Andreas Hohenleutner and
• Burkhard König

Beilstein J. Org. Chem. 2013, 9, 2088–2096, doi:10.3762/bjoc.9.245

• known to undergo a variety of reactions with nitrogen heterocycles [18] and might thus attack the emitters, leading to the formation of a variety of deterioration products. We therefore performed the irradiation experiments in different solvents under atmospheric as well as inert conditions (freeze-pump

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• intermolecular or intramolecular manner have been employed in some transformations that are highly useful. Prominent examples are the Minisci reaction [11][12][13][14][15] for the preparation of mainly nitrogen heterocycles and Zard’s homolytic substitution reactions at nitrogen heterocycles with xanthates as

Synthesis of 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones and novel ring contraction and fusion reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] into 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones

• Lidia S. Konstantinova,
• Kirill A. Lysov,
• Ljudmila I. Souvorova and
• Oleg A. Rakitin

Beilstein J. Org. Chem. 2013, 9, 577–584, doi:10.3762/bjoc.9.62

• far, no general approach to their synthesis has been proposed, and yields are often low. 3-Methyl-2-thioxo-2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-dione has been shown to possess a fungicidal activity to Pyricularia Oryzae [4][5]. A family of thiazolonaphthoquinones fused on a chain with nitrogen

• heterocycles (pyrrole [6][7], and triazoles [8]) were found to possess antifungal and antitumor activity toward a number of species causing fungal diseases and toward Walker 256 carcinoma cell lines. The compounds with the thiazoloanthroquinone structure have not been reported in the literature so far. We were

Synthesis of SF₅-containing benzisoxazoles, quinolines, and quinazolines by the Davis reaction of nitro-(pentafluorosulfanyl)benzenes

• Petr Beier and
• Tereza Pastýříková

Beilstein J. Org. Chem. 2013, 9, 411–416, doi:10.3762/bjoc.9.43

• powder in aqueous acetic acid according to the literature procedure (Table 2) [31]. Aminoketones 10 and 11 were investigated as starting substrates in the synthesis of various nitrogen heterocycles by condensation reactions. Several reliable synthetic methods giving quinolones [32][33] or quinazolines

Dipyrazolo[1,5-a:4',3'-c]pyridines – a new heterocyclic system accessed via multicomponent reaction

• Wolfgang Holzer,
• Gytė Vilkauskaitė,
• Eglė Arbačiauskienė and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2012, 8, 2223–2229, doi:10.3762/bjoc.8.251

• multicomponent reaction affording new tricyclic compounds with a dipyrazolo[1,5-a:4',3'-c]pyridine core. Detailed NMR spectroscopic investigations (1H, 13C and 15N) were undertaken with all obtained compounds. Keywords: cyclization; nitrogen heterocycles; NMR spectroscopy; multicomponent reaction; pyrazole

Engineering of indole-based tethered biheterocyclic alkaloid meridianin into β-carboline-derived tetracyclic polyheterocycles via amino functionalization/6-endo cationic π-cyclization

• Piyush K. Agarwal,
• Meena D. Dathi,
• Mohammad Saifuddin and
• Bijoy Kundu

Beilstein J. Org. Chem. 2012, 8, 1901–1908, doi:10.3762/bjoc.8.220

• ring to facilitate cationic π-cyclization. Keywords: cyclization; indole; meridianin; natural products; nitrogen heterocycles; Introduction Indole is an important pharmacophore present in many natural and designed polyheterocyclic synthetic products of therapeutic importance [1][2][3]. The range of

Access to pyrrolo-pyridines by gold-catalyzed hydroarylation of pyrroles tethered to terminal alkynes

• Elena Borsini,
• Gianluigi Broggini,
• Andrea Fasana,
• Chiara Baldassarri,
• Angelo M. Manzo and
• Alcide D. Perboni

Beilstein J. Org. Chem. 2011, 7, 1468–1474, doi:10.3762/bjoc.7.170

• -azepines. Keywords: C–C coupling; gold catalysis; homogeneous catalysis; nitrogen heterocycles; rearrangement; Introduction Intramolecular transition-metal-catalyzed reactions represent one of the most challenging routes for the preparation of heterocyclic compounds [1][2][3][4][5]. Methodologies

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• addition of diethylphosphite. Moderate to good yields were obtained depending on the nature of the various components (Scheme 14) [13]. Amines as hetero-Michael donors Many multicomponent approaches to nitrogen heterocycles have been developed based on the reaction of nitrogen-centered nucleophiles with α

• Ma and coworkers for the selective preparation of five-membered nitrogen heterocycles starting from allene-bearing nucleophilic centers [41]. In this context, the same authors developed a new synthesis of substituted imidazolidinones 75 through a palladium-catalyzed, three-component reaction of 2,3

Combination of gold catalysis and Selectfluor for the synthesis of fluorinated nitrogen heterocycles

• Antoine Simonneau,
• Pierre Garcia,
• Jean-Philippe Goddard,
• Virginie Mouriès-Mansuy,
• Max Malacria and
• Louis Fensterbank

Beilstein J. Org. Chem. 2011, 7, 1379–1386, doi:10.3762/bjoc.7.162

• [11], as well as the studies from Nevado [3], Hammond and Xu [12], Liu and Xu [13], and Liu [14], we were attracted by the possibility to access fluorinated nitrogen heterocycles 2a and 2b by performing subsequently an intramolecular nucleophilic attack of nitrogen onto the gold-activated triple bond

• aminoalkynes into valuable nitrogen heterocycles substituted by a fluorine atom in position 3 of the ring. This could certainly be applied to the synthesis of biologically relevant substrates. Current efforts are being made in this direction and a more exemplified study will be reported in due course

Long-range diastereoselectivity in Ugi reactions of 2-substituted dihydrobenzoxazepines

• Luca Banfi,
• Andrea Basso,
• Valentina Cerulli,
• Valeria Rocca and
• Renata Riva

Beilstein J. Org. Chem. 2011, 7, 976–979, doi:10.3762/bjoc.7.109

• with chiral amines as auxiliaries [6], or with chiral cyclic imines. The use of cyclic imines (three-component Ugi–Joullié reaction) [7][8] is particularly useful, because the resulting Ugi products are necessarily nitrogen heterocycles. However, good diastereoselectivity has been obtained so far only

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• )-catalyzed opening of the VCP moiety embedded in an azapolycyclic system occurs at high temperature (110–130 °C) to afford the corresponding 1,3-dienes in moderate yield (34–53%). Keywords: nitrogen heterocycles; rearrangement; rhodium; small ring systems; spiro compounds; Introduction The cyclopropyl

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• -dielectrophiles has been extensively used for the preparation of bicyclic nitrogen heterocycles, especially in the preparation of condensed heterocycles such as pyrazolo[3,4-d]pyrimidines, pyrazolo[3,4-b]pyridines, imidazopyrazoles etc. In view of significant interest in the synthesis of these heterocyclics, we

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• ], and δ-azidoesters and chlorides into allylated nitrogen heterocycles [30]. To help in elucidating the mechanisms of these reductions, we used CW EPR spectroscopy and attempted to characterise the reactive intermediates in selected reactions involving gallium trichloride. Surprisingly, we found that