Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• heterocycle, and the benzene moiety can tolerate all manner of substituents in all positions, however, only mono-substituted systems are explored. This is a powerful procedure, which allows for the circumvention of traditional Pd or Cu catalysed couplings of heteroarenes, which are notoriously difficult. A

• encompass structurally diverse and relatively delicate scaffolds, making it suitable for LSF, would make this an incredibly valuable tool to the medicinal chemist. 3 Heterocycle formation The importance and prevalence of heterocyclic systems in medicinal chemistry cannot be overstated. Although reactions

• the anti-configuration in all cases. In addition, the option for oxidation to the oxazole or thiazole is always enticing as a way of easily accessing a diverse set of molecules. Immediately akin to the oxazole moiety is the oxadiazole heterocycle, which exhibits similar properties. There are several

Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant

• Irina A. Mironova,
• Pavel S. Postnikov,
• Rosa Y. Yusubova,
• Akira Yoshimura,
• Thomas Wirth,
• Viktor V. Zhdankin,
• Victor N. Nemykin and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159

• ) heterocycle (2-iodosylbenzenesulfonic acid), while the oxidation of sodium 2-iodobenzenesulfonate in neutral aqueous solution gives the iodine(V) products. Keywords: hypervalent iodine; iodine; 2-iodoxybenzenesulfonic acid; oxidation; X-ray; Introduction Recently, the interest in synthetic applications of

• ) heterocycle, 2-iodosylbenzenesulfonic acid (4) as main product. The direct oxidation of 2-iodobenzenesulfonic acid (2) with Oxone leads to the formation of the desired IBS (1, Scheme 1), however, contaminated with inorganic impurities. Because of the high solubility of IBS in water, this mixture is difficult

• of IBS, 2-iodosylbenzenesulfonic acid, by using periodic acid as an oxidant. We have demonstrated that the oxidation of free 2-iodobenzenesulfonic acid under acidic conditions affords an iodine(III) heterocycle, while the oxidation of sodium 2-iodobenzenesulfonate in neutral aqueous solution gives

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3⁺ + 2]-cycloaddition/rearrangement reactions

• Lin-bo Luan,
• Zi-jie Song,
• Zhi-ming Li and
• Quan-rui Wang

Beilstein J. Org. Chem. 2018, 14, 1826–1833, doi:10.3762/bjoc.14.155

• achieved when a third heterocycle, especially a 1,2,4-triazolo moiety, was attached to the seven-membered ring as part of 1,4-benzodiazepine [13][14]. Among various reported 1,2,4-triazole-annulated 1,4-benzodiazepines, triazolam (I), estazolam (II), alprazolam (III) and pyrazolam (IV) are prominent

Synthesis of pyrimido[1,6-a]quinoxalines via intermolecular trapping of thermally generated acyl(quinoxalin-2-yl)ketenes by Schiff bases

• Svetlana O. Kasatkina,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Ivan G. Mokrushin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2018, 14, 1734–1742, doi:10.3762/bjoc.14.147

• (quinoxaline fused by a six-membered heterocycle at the [a]-side) are promising biologically active compounds. Recent research studies revealed that they can act as inhibitors of poly(ADP-ribose) polymerase (PARP) [3], inhibitors of hepatitis C virus [4], 5-HT2C agonists [5][6][7], substances for controlling

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• branch-cells, (ii) basicity and conformational nature of the diaza-six-membered saturated heterocycle as linker and (iii) the global molecular shape, the resulted 4-aminophenol-based melamines displayed relevant redox properties [36] and, in some cases, selective aptitudes to produce MOFs (metal-organic

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• been further extended to the synthesis of a new series of molecules 77, where the central thiophene moiety is replaced by a 6-membered heterocycle, which is substituted by a gem-dimethyl or a cyclopropyl group. In this case, the reaction can be performed under metal-free conditions in the presence of a

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• triazole ring can be confirmed by the examination of the fingerprint region. According to literature, the presence of the heterocycle linker is accounted for by the occurrence of a tiny signal at 1242 cm−1 [11]; moreover, new bands are present in the spectrum of CaNS2 at 1296, 1050 and 1026 cm−1, which

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• reaction sequence proceeds under metal-free conditions, the selective transfer of the more electron-deficient aryl group of the unsymmetrical iodonium salts 1 is achieved. The N-arylated heterocycle NAr1 then serves as the directing group in the following ortho-C–H functionalisation with the iodoarene as

Synthesis of pyrazolopyrimidinones using a “one-pot” approach under microwave irradiation

• Mark Kelada,
• John M. D. Walsh,
• Robert W. Devine,
• Patrick McArdle and
• John C. Stephens

Beilstein J. Org. Chem. 2018, 14, 1222–1228, doi:10.3762/bjoc.14.104

• groups. Keywords: microwave-assisted synthesis; nitrogen-fused heterocycle; one-pot; pyrimidinone; Introduction The pyrazolo[1,5-a]pyrimidinone is a fused nitrogen-containing heterocyclic system and is of interest due to its role as a basic core scaffold in many bioactive and pharmaceutically relevant

Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle

• Akira Yoshimura,
• Michael T. Shea,
• Cody L. Makitalo,
• Melissa E. Jarvi,
• Gregory T. Rohde,
• Akio Saito,
• Mekhman S. Yusubov and
• Viktor V. Zhdankin

Beilstein J. Org. Chem. 2018, 14, 1016–1020, doi:10.3762/bjoc.14.87

• , Duluth, MN 55811, USA, Division of Applied Chemistry, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan 10.3762/bjoc.14.87 Abstract A new bicyclic organohypervalent iodine heterocycle derivative of benziodazole was prepared by

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides

• Kartik Temburnikar and
• Katherine L. Seley-Radtke

Beilstein J. Org. Chem. 2018, 14, 772–785, doi:10.3762/bjoc.14.65

• -dideazaadenine C-nucleosides [63][64][65][69][70]. A. Reaction of D-ribonolactone and lithiated heterocycle leading to C1'-substituted C-nucleosides. Steroechemical scrambling is observed when ring opened form of ribose is employed during nucleophilic substitution. B. Synthesis of C2' C-nucleosides using

Sequential Ugi reaction/base-induced ring closing/IAAC protocol toward triazolobenzodiazepine-fused diketopiperazines and hydantoins

• Robby Vroemans,
• Fante Bamba,
• Jonas Winters,
• Joice Thomas,
• Jeroen Jacobs,
• Luc Van Meervelt,
• Jubi John and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 626–633, doi:10.3762/bjoc.14.49

• heterocycle formation and the other an IAAC. Unlike some of the reported strategies using Cu-catalyzed IAAC [13][15], we postulated that the intramolecular dipolar cycloaddition would proceed under thermal conditions (metal-free) due to the close proximity of the azide and similar functionalities in the

• conformational restrictions prevent the side chains on the benzodiazepine bearing the amide and halogen to be in close proximity, which is needed for the reaction to proceed. The generality of the developed fused-heterocycle synthesis was studied with substituted azidoaldehyde, isocyanides and chloroacetic acid

• successful in synthesizing chloro derivatives 7i and 7j from 2-azido-4-chlorobenzaldehyde (1c). The multiring-fused heterocycle synthesis was also tried with an azidobenzaldehyde bearing electron-donating substituents; the reaction with 2-azido-4,5-dimethoxybenzaldehyde (1d) yielded the product 7k in lesser

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• benzyl or heterocycle groups and release of the unmodified sequences. Modifications at the internucleotide linkage: ONs containing either 5-nitro-2-furylmethyl or 5-nitro-2-thiophenylmethyl modifications at some internucleoside phosphates were converted to native (dT)n with good hypoxia selectivity in

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• with the azasiline donor, OLEDs displaying the unprecedented EQE of 22.3% were obtained [46]. As specificity, azasiline is a 6-membered heterocycle comprising a silicon atom introduced instead of a carbon atom to enlarge the HOMO–LUMO gap and lower the HOMO level. Due to the sp3 hybridization of the

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• -pot sequential synthesis of the trisubstituted 5-(pyridine-2-yl)thiophenes 8a. Substrate: amalonitrile; b5,5-dimethylcyclohexane-1,3-dione. The substitution reaction with MeOH. Examination of N,S-acetals substituted with a heterocycle (7aa–k) or an arene (7l–p). 1H NMR studies of Meldrum’s acid-based

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• reaction with different electron-rich, halogenated or heterocycle substituted alkynes, affording the respective products in good to moderate yields. Strongly electron-withdrawing nitro, acyl or cyano groups were not suitable. In accordance to the proposed mechanism, the reaction with 2-iodothioanisoles

A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• azlactone dimer, which is a versatile heterocycle containing two stereogenic centers (Figure 1). Kobayashi and co-workers demonstrated the rich reactivity of azlactones conducting the dimerization reaction using strong bases as catalysts; however, higher temperatures and long reaction times were required

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• (Table 2, entries 1–16). The presence of the ester functionality at position 5 of the heterocycle led to product mixtures if toluene was used as solvent so that products 4j–m could not be obtained selectively and separated. In DMSO solution, the corresponding Michael-type adducts 5j–m were smoothly

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

• Jury J. Medvedev,
• Ilya V. Efimov,
• Yuri M. Shafran,
• Vitaliy V. Suslonov,
• Vasiliy A. Bakulev and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2017, 13, 2569–2576, doi:10.3762/bjoc.13.253

• cannot exclude an alternative route when the carbenoid interacts with the cyano group to yield an oxazole heterocycle [39][40][41][42][43][44][45]. Herein we present the first detailed results of this study. Results and Discussion To determine the scope and limitations of these reactions, several

• photosensitivity and hence could be used in OLED devices [68]. Also these compounds display high nucleophilicity in reactions with electrophiles which are often accompanied by a variety of thiophene heterocycle transformations, and hence could be successfully used for their further functionalization [69

A novel synthetic approach to hydroimidazo[1,5-b]pyridazines by the recyclization of itaconimides and HPLC–HRMS monitoring of the reaction pathway

• Dmitry Yu. Vandyshev,
• Khidmet S. Shikhaliev,
• Andrey Yu. Potapov,
• Michael Yu. Krysin,
• Fedor I. Zubkov and
• Lyudmila V. Sapronova

Beilstein J. Org. Chem. 2017, 13, 2561–2568, doi:10.3762/bjoc.13.252

• [1,5-b]pyridazines along route B, 1-aminoimidazoles with no substituents at the C-5 atom of the original heterocycle and 1,3-dielectrophilic reagents are used, e.g., 1,3-diketones [24][25][26], β-ketoesters [24], α,β-unsaturated ketones [27][28], including those obtained in situ [29][30] or containing

A concise flow synthesis of indole-3-carboxylic ester and its derivatisation to an auxin mimic

• Marcus Baumann,
• Ian R. Baxendale and
• Fabien Deplante

Beilstein J. Org. Chem. 2017, 13, 2549–2560, doi:10.3762/bjoc.13.251

• chemistry; heterocycle; hydrogenation; indole; multistep; Introduction Indoles are amongst the most important bioactive heterocyclic structures being commonly encountered in the amino acid tryptophan (1), the related neurotransmitter serotonin (2) as well as numerous complex alkaloid natural products and

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

• Sergey L. Deev,
• Alexander S. Paramonov,
• Tatyana S. Shestakova,
• Igor A. Khalymbadzha,
• Oleg N. Chupakhin,
• Julia O. Subbotina,
• Oleg S. Eltsov,
• Pavel A. Slepukhin,
• Vladimir L. Rusinov,
• Alexander S. Arseniev and
• Zakhar O. Shenkarev

Beilstein J. Org. Chem. 2017, 13, 2535–2548, doi:10.3762/bjoc.13.250

• ] (Figure 1B). For this reason, the adamantylation of compounds 5 and 6 led to mixtures of N3- and N4-adamantylated isomers, which reisomerized into each other likely via the formation of an adamantyl cation and starting NH-heterocycle. The unambiguous determination of N-adamantylation site(s) in

• ]triazinone 19-15N2. Previously, the same approach was described for the incorporation of 15N atoms in azole and azine rings of compound 4 [38]. Heterocycle 20-15N2 was obtained by the treatment of 19-15N2 with hydrobromic acid according to a procedure described for 6-nitro-1,2,4-triazolo[5,1-c][1,2,4]triazin

• observed by NMR spectroscopy in DMSO solution (≈10:7). Interestingly, for 15a, the major conformer corresponds to a rotameric state with a screened N1 atom, but in the major conformer of 15b, the N2 atom of the heterocycle is screened. Notably, similar structural disorder was previously observed in the

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• time, the 1,2,3-triazoles became the heterocycle of choice in drug discovery, due to their favourable pharmacokinetic and safety profiles, hydrogen-bonding capability, moderate dipole moment, rigidity and stability under in vivo conditions [5][6]. Also, the ability of 1,2,3-triazoles to act as amide

• derivatives and it was largely helpful for calculating the Raman spectra for monitoring purposes. It corroborated the substitution of the phenyl-1-(1,2,3-triazolyl)methyl unit at O-4 position of the quinolone heterocycle and formation of the 1,2,3-triazole ring in compounds 5–8 (Figure 5 and Supporting

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• afforded azafulvene derivatives 91 (Scheme 34) [82]. Remarkably, the formation of five-membered cyclic nitrone through N-attack of the oxime on the cyano group is more preferable over the six-membered N–O heterocycle. C-Nucleophiles possessing leaving groups have been also used in the construction of N–O

High-speed vibration-milling-promoted synthesis of symmetrical frameworks containing two or three pyrrole units

• Marco Leonardi,
• Mercedes Villacampa and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2017, 13, 1957–1962, doi:10.3762/bjoc.13.190

• vibration milling (HSVM) [14][15]. The importance of pyrrole frameworks stems from the status of this heterocycle as a privileged structure in drug discovery due to its presence as a structural core in molecules that are able to bind various receptors [16]. Results and Discussion Our route to the target