Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• (90–105 kcal/mol) to form a new, weaker C–M bond (50–80 kcal/mol), followed by generation of a new C–C bond. Generally, transition metal-catalyzed sp2 C–H activation is facilitated by directing groups [10][11][12][13] or heteroatoms in the heterocyclic compounds [14][15][16][17][18]. This methodology

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• heterocyclic compounds is steadily growing, heterocyclic chemistry remains in the focus of the synthetic community. Enormous efforts have been made in the last decades in order to render the production of such compounds more selective and efficient. However, most of the conventional methods for the

• products contain at least one heterocyclic unit, the particular importance of heterocyclic compounds becomes clear [2]. Most of the classical methods for heterocycle synthesis are based on the use of acids or bases at elevated temperatures, conditions which are often not compatible with the presence of

• conducted at low temperatures. The electrochemical synthesis of heterocyclic compounds can be considered as a mature discipline. The last comprehensive review dealing with electrochemical heterocycle generation has been published in 1997 by Tabaković [26]. Earlier reviews on different aspects of the

New highlights of the syntheses of pyrrolo[1,2-a]quinoxalin-4-ones

• Emilian Georgescu,
• Alina Nicolescu,
• Florentina Georgescu,
• Florina Teodorescu,
• Daniela Marinescu,
• Ana-Maria Macsim and
• Calin Deleanu

Beilstein J. Org. Chem. 2014, 10, 2377–2387, doi:10.3762/bjoc.10.248

• constituent of several bioactive heterocyclic compounds that demonstrate interesting activity against Mycobacterium tuberculosis [1], anti-HIV [2], anticancer [3], and it modulates the estrogen receptor activity [4]. Synthetic methods towards pyrrolo[1,2-a]quinoxaline derivatives based on pyrroles [5], or

• towards N-bridged heterocyclic compounds [17][18][19][20] prompted us to investigate the one-pot three-component reactions of various substituted benzimidazoles with alkyl bromoacetates and electron-deficient alkynes in presence of an epoxide. Herein, we report a simple one-pot three-component synthetic

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• variety of methods for enantioselective syntheses of structurally diverse acyclic, carbocyclic, and heterocyclic compounds. 2.1 [3 + 2] Annulation of allenes with activated alkenes Nucleophilic phosphine-catalyzed annulations have been established as very useful tools for the syntheses of carbo- and

• substrate scope was, however, very limited. 2.2 [3 + 2] Annulations of allenes with activated imines Phosphine-catalyzed [3 + 2] annulation of allenes with activated imines has emerged as an important tool for the synthesis of functionalized pyrrolines, which are valuable heterocyclic compounds for the

• stereoselectivities (up to 99% ee, up to 99:1 dr) and moderate to excellent yields (42–99%). The piperidine products could be transformed conveniently into biologically important heterocyclic compounds. For example, with this asymmetric [4 + 2] annulation as the key step, using indole-2-carboxaldehyde as the starting

Synthesis of trifluoromethyl-substituted pyrazolo[4,3-c]pyridines – sequential versus multicomponent reaction approach

• Barbara Palka,
• Angela Di Capua,
• Maurizio Anzini,
• Gyté Vilkauskaité,
• Algirdas Šačkus and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2014, 10, 1759–1764, doi:10.3762/bjoc.10.183

• substituent, including important drug molecules in different pharmaceutical classes [5]. Keeping in mind the above facts, the synthesis of fluorinated heterocyclic compounds, which can act as building blocks for the construction of biologically active fluorine-containing molecules, is of eminent interest. In

Microwave-assisted Cu(I)-catalyzed, three-component synthesis of 2-(4-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-1H-benzo[d]imidazoles

• Yogesh Kumar,
• Vijay Bahadur,
• Anil K. Singh,
• Virinder S. Parmar,
• Erik V. Van der Eycken and
• Brajendra K. Singh

Beilstein J. Org. Chem. 2014, 10, 1413–1420, doi:10.3762/bjoc.10.145

• characterized by an appreciable chemical and biological importance. The synthesis of nitrogen-containing heterocyclic compounds and their derivatives plays an important role in organic chemistry as they frequently exhibit therapeutic and pharmacological properties. They have emerged as an integral backbone of

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• ; cobalt complex; metalloradical catalysis; organophosphorus; phosphoryl azide; Introduction Aziridines, the smallest three-membered nitrogen-containing heterocycles, are highly valuable heterocyclic compounds that are widely used in organic synthesis and pharmaceuticals [1][2]. As a result, tremendous

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• tolerance. Moreover, the produced selenones could be useful intermediates for the synthesis of different heterocyclic compounds. Keywords: heterocycles; monoperoxyphthalate; oxidation; selenides; selenones; Introduction Organoselenium compounds have received considerable attention in recent times because

• different alkyl phenyl selenides to the corresponding selenones. Since the phenylselenonyl group is an excellent leaving group, selenone 2 readily undergoes SN2 type substitution reactions with common nucleophiles [7][8] as shown in Scheme 2. A wide range of heterocyclic compounds can be obtained by

• intermediates which readily undergo intramolecular SN2 type substitution reactions to afford a range of heterocyclic compounds (Table 2, entries 2–7) and benzeneseleninic acid. Thus, the oxidation of β-hydroxyalkyl phenyl selenide 1e gave, in tetrahydrofuran and in the presence of dipotassium hydrogen phosphate

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• –heteroatom bond formation via C–H activation has received attention owing to the omnipresence of heterocyclic compounds in nature [8]. Recently, it has been demonstrated that the intramolecular bond formation between a heteroatom and a vicinal unreactive C–H is an efficient method for the synthesis of

Regioselective S_N2' Mitsunobu reaction of Morita–Baylis–Hillman alcohols: A facile and stereoselective synthesis of α-alkylidene-β-hydrazino acid derivatives

• Silong Xu,
• Jian Shang,
• Junjie Zhang and
• Yuhai Tang

Beilstein J. Org. Chem. 2014, 10, 990–995, doi:10.3762/bjoc.10.98

• nitrogen-containing heterocyclic compounds, especially pyrazole derivatives [2][3][4][5][6][7]. Although various methods detailing the synthesis of hydrazines have been established [8], the development of an efficient synthesis of hydrazines with highly structural diversity from simple starting materials

• synthesis of nitrogen-containing heterocyclic compounds. Experimental General information All reactions were carried out in nitrogen atmosphere under anhydrous conditions. Solvents were purified according to standard procedures. Mortia–Baylis–Hillman (MBH) alcohol 1 were prepared according to literature

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

Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles

• Antonio Arcadi,
• Emanuela Pietropaolo,
• Antonello Alvino and
• Véronique Michelet

Beilstein J. Org. Chem. 2014, 10, 449–458, doi:10.3762/bjoc.10.42

• methodologies for the selective preparation of fluorinated heterocyclic compounds is therefore still highly challenging [4][5]. The variation of the indole structure has been a field of high interest for a long time, considering the importance of this skeleton as a ubiquitous skeleton of pharmaceuticals and

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels–Alder reactions

• Salah Fadel,
• Youssef Hajbi,
• Mostafa Khouili,
• Said Lazar,
• Franck Suzenet and
• Gérald Guillaumet

Beilstein J. Org. Chem. 2014, 10, 282–286, doi:10.3762/bjoc.10.24

• class of heterocyclic compounds and include many substances of both biological and chemical interest [1][2][3][4]. Prevention and treatment of angiogenic disorders and cancers were realized with this class of heterocyclic derivatives [5]. They show anti-allergic [6], anti-inflammatory [7], antibacterial

• -demand Diels–Alder reaction under microwave irradiation [22][23][24]. The use of 1,2,4-triazines in inverse electron-demand Diels–Alder reactions proved to be an efficient strategy for the construction of various heterocyclic compounds [25][26][27], such as azacarbazoles [28][29][30][31][32][33

Four-component reaction of cyclic amines, 2-aminobenzothiazole, aromatic aldehydes and acetylenedicarboxylate

• Hong Gao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 2934–2939, doi:10.3762/bjoc.9.330

• preparation of the mixed heterocyclic compounds containing units of benzothiazole, piperidine and 2-pyrrolidinone in satisfactory yields. The range of substrates and the reaction mechanism for this reaction were briefly discussed. This convenient synthetic reaction might be potentially used for complex

An efficient method for the construction of polysubstituted 4-pyridones via self-condensation of β-keto amides mediated by P₂O₅ and catalyzed by zinc bromide

• Liquan Tan,
• Peng Zhou,
• Cui Chen and
• Weibing Liu

Beilstein J. Org. Chem. 2013, 9, 2681–2687, doi:10.3762/bjoc.9.304

• ; self-condensation; Introduction β-Keto amide and their derivatives are desired classes of intermediates for the synthesis of nitrogen- and oxygen-containing heterocyclic compounds since they possess six reactive sites in the same molecule (Scheme 1) [1][2][3][4][5][6][7]. A lot of reports can be found

• in the literature concerning the construction of different heterocyclic compounds from β-keto amides by modification of the six different reactive positions [8][9][10][11][12][13]. Our interest in the fields of cleavage or construction of C–C and C–hetero bonds using β-keto amides and their

• well known that 4-pyridones are one of the most important classes of heterocyclic compounds as they are a key structural attribute of many bioactive natural products [21][22][23][24][25][26][27]. Besides, many of the 4-pyridones have shown interesting biological activities, such as antibacterial [24

Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

• Fei Zhao,
• Lei Zhang,
• Hailong Liu,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

• efficient CuI-catalyzed methodology for the synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives. This approach rapidly achieved the tetracyclic products with good to excellent yields in short reaction time under microwave irradiation. We anticipate that these important heterocyclic compounds that

Oxidative 3,3,3-trifluoropropylation of arylaldehydes

• Akari Ikeda,
• Masaaki Omote,
• Shiho Nomura,
• Miyuu Tanaka,
• Atsushi Tarui,
• Kazuyuki Sato and
• Akira Ando

Beilstein J. Org. Chem. 2013, 9, 2417–2421, doi:10.3762/bjoc.9.279

• substrates decreased the yield of the products substantially, probably because of the steric hindrance introduced by the substituent (Table 2, entries 10 and 11). While the reaction could be applied to polycyclic and heterocyclic compounds, 3m and 3n were only obtained in low yield (Table 2, entries 12 and

A one-pot synthesis of 3-trifluoromethyl-2-isoxazolines from trifluoromethyl aldoxime

• Raoni S. B. Gonçalves,
• Michael Dos Santos,
• Guillaume Bernadat,
• Danièle Bonnet-Delpon and
• Benoit Crousse

Beilstein J. Org. Chem. 2013, 9, 2387–2394, doi:10.3762/bjoc.9.275

• yield the corresponding trifluoromethylated γ-amino alcohols. Keywords: aldoxime; amino alcohol; fluorine; isoxazole; isoxazoline; organo-fluorine; Introduction 2-Isoxazolines are five-membered heterocyclic compounds that have been widely applied in medicinal and organic chemistry. This nucleus is

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• large number of functional groups and therefore has various uses in organic synthesis and can also be exploited for the preparation of heterocyclic compounds. Isocyanate derivatives can be generally obtained in good yields. However, it is necessary to avoid the traditional triphenylphosphine to obtain

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• reusable solid supported/heterogeneous catalyst for the efficient synthesis of heterocyclic compounds remains a challenge to chemists in laboratories and in the industry [22][23]. Reactions with reagents that are immobilized on inorganic solid supports show several advantages over the conventional

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• of an increase in the molecular diversity, offering a suitable strategy intended for library discovery. It is well known that metal-catalyzed hydroarylation is a powerful reaction to prepare benzofused heterocyclic compounds [29][30][31]. Pt(IV) [32], Pt(II) and Au(I) [33] complexes were early

• recognized as suitable catalysts to convert aryl propargyl ethers into chromenes. Nowadays, alternative gold(I)-based catalysts have been successfully exploited to further prepare substituted 2H-chromenes [34][35][36][37][38], as well as a wide variety of relevant heterocyclic compounds [39][40]. On the

An easy direct arylation of 5-pyrazolones

• Hao Gong,
• Yiwen Yang,
• Zechao Wang and
• Chunxiang Kuang

Beilstein J. Org. Chem. 2013, 9, 2033–2039, doi:10.3762/bjoc.9.240

• synthesize a new series of heterocyclic compounds containing the pyrazolone moiety. The reaction of pyrazolones with arylboronic acids is an attractive approach for the synthesis of arylpyrazolone [15][16]. However, it often needs pre-formation of halo-pyrazolones. Transition metal-catalyzed direct arylation

• ). Conclusion In summary, we developed a mild, simple and efficient method for the direct arylation of 5-pyrazolones by Pd-catalyzed C–H bond activation. This approach resulted in the construction of 4-aryl-5-pyrazolones, which are important heterocyclic compounds used in medicinal and biological research. The

The first example of the Fischer–Hepp type rearrangement in pyrimidines

• Inga Cikotiene,
• Mantas Jonusis and
• Virginija Jakubkiene

Beilstein J. Org. Chem. 2013, 9, 1819–1825, doi:10.3762/bjoc.9.212

• Fischer–Hepp rearrangement takes place when N-nitroso secondary anilines are treated with HCl or HBr, other acids give poor results or none at all. To the best of our knowledge, there are no examples of the migration of a nitroso group in heterocyclic compounds in the scientific literature. Obviously, the

A simple, enaminone-based approach to some bicyclic pyridazinium tetrafluoroborates

• František Josefík,
• Markéta Svobodová,
• Valerio Bertolasi and
• Petr Šimůnek

Beilstein J. Org. Chem. 2013, 9, 1463–1471, doi:10.3762/bjoc.9.166

• using a more reactive diazonium salt before a less reactive one. Keywords: azo coupling; diazonium salt; enaminone; pyridazinium; Introduction As heterocyclic compounds play a very important role in everyday life, e.g., as pharmaceuticals, agrochemicals, dyes, etc. (for many monographies or textbooks