Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• reactive intermediates. After a short introduction on activation modes in photocatalysis, selected case studies where organic dyes have been exploited for generating carbon-centered radicals, charged open-shell species, and heteroatom-centered radicals will be covered. The last short section will be

• )) radicals are important reactive intermediates for the construction of C–C and C–heteroatom bonds [31]. Their addition onto unsaturated systems, such as olefins and arenes, is particularly efficient. Additionally, alkyl radicals can undergo translocations, abstracting atoms from different sites. Recently

• for the synthesis of the arylated heteroarenes 12.3 via an intermolecular process [79]. Alemán and co-workers used PHTH (OD16) for the synthesis of various heteroatom-containing bicycles 12.4 through a tethered electrophile approach [80]. For the second strategy, König and co-workers developed an

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• catalysts in both oxidative and reductive quenching. The use of porphyrins as a photosensitizer for singlet oxygen generation is presented in the second topic, which was subdivided into two sections: pericyclic reactions and heteroatom oxidations. The first section describes the use of singlet oxygen in

• pericyclic reactions with olefins and dienes, and the second deals with heteroatom oxidations carried out by singlet oxygen. Review Porphyrins as photoredox catalysts Porphyrins and metalloporphyrins have been extensively studied as photosensitizers in singlet oxygen generation, but underexploited as

• (bpy)3)]2+, [Ir(ppy)3], eosin Y, and 4CzTPN [12] (Figure 3). However, some porphyrin and metalloporphyrin derivatives possess adequate potentials to be applied as photoredox catalysts in C–C and C-heteroatom bond formations [10][22]. Furthermore, supramolecular porphyrin-containing molecules, such as

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• )- and (E)-alkenes 311 afforded the (E)-alkene 312 as the major product. The targeted γ-borylated compounds (relative to the leaving group) were formed, each with high enantioselectivity, which can be used for further stereoselective C–C and C–X (X = heteroatom) bond formation. Catalytic Cu(NHC)-mediated

• addition (e.g., 351, 352). It was shown that the presence of a heteroatom plays a crucial role due to the otherwise non-selective, facile addition of Cu-Bpin to alkenes (Scheme 56) [103]. Based on previous studies on asymmetric 3-component carboboration of styrene derivatives [104] and 1,3-dienes [105

Synthesis of six-membered silacycles by borane-catalyzed double sila-Friedel–Crafts reaction

• Yafang Dong,
• Masahiko Sakai,
• Kazuto Fuji,
• Kohei Sekine and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2020, 16, 409–414, doi:10.3762/bjoc.16.39

• ][6][7][8][9][10], and reagents [11][12][13][14]. Therefore, the development of new methods to construct silacyclic skeletons is highly desirable. These compounds are commonly synthesized upon the reaction of heteroatom-bridged dilithiated diaryl compounds, such as dilithiated diaryl ethers and

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• occurs selectively on the end opposite to the phosphorus donor atom [48]. This is because the position trans to the heteroatom, with greater π-acceptor character, is more electrophilic than the one opposite the σ-donor atom [9]. One can modify this electronic imbalance by attaching vicinal heteroatoms

• from α-C–H bond activation in heterocycles The α-position to a heteroatom in a cyclic compound is activated because of the difference in electronegativity with carbon. This presents an opportunity to readily generate organometallic nucleophiles. Chelucci et al. [71] used this fact to synthesize the

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• -acetate hexacarbonyl dicobalt complexes and a Lewis or Brønsted acid. A range of heteroatom nucleophiles have been incorporated into alkyne dicobalt complexes by this chemistry [34][35][36][37][38][39][40]. However, reactions with carbon-based nucleophiles provide an opportunity to access the structurally

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• biologically inert, irradiation with violet light effectively "uncaged" agonist activity, but in a photoreversible manner. Since the neurotransmitter acetylcholine has fully saturated heteroatom valences, our photoswitchable 4FABTA probe could be useful for physiological studies of this neurotransmitter

Iodine-mediated hydration of alkynes on keto-functionalized scaffolds: mechanistic insight and the regiospecific hydration of internal alkynes

• Zachary Lee,
• Brandon R. Jones,
• Nyochembeng Nkengbeza,
• Michael Phillips,
• Kayla Valentine,
• Alexis Stewart,
• Brandon Sellers,
• Nicholas Shuber and
• Karelle S. Aiken

Beilstein J. Org. Chem. 2019, 15, 2747–2752, doi:10.3762/bjoc.15.265

• hydration reaction of alkynes serves as a green alternative to metal-catalyzed procedures. Previous work has shown that this method works well with terminal alkynes on keto-functionalized scaffolds, including 1,3-dicarbonyls and their heteroatom analogues. It was hypothesized that the reaction proceeds

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• used to architect various ring-fused S-heteroacenes, which have been studied extensively [8][9][10] due to their better characteristics compared to heteroatom-free acenes. For instance, S-heteroacenes have a better oxidation stability due to lower-lying HOMO levels, as well as more efficient charge

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• , Supporting Information File 1) and the photoisomerization are observed. When the substituent Y is a halogen atom, we observe a slight bathochromic shift of the π–π* band to higher wavelengths with increasing size of the heteroatom, from 323 nm for Y = H (3e) to 339 nm for Y = I (6e) (Table 3, Figure 4A

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• ]. Yet another approach is the use of heteroatom-modified farnesyl diphosphates that could be still cyclized by TPSs yielding unnatural terpenoids [105]. CotB1 synthesizes geranylgeranyl diphosphate (GGDP) 3 from the substrates dimethylallyl diphosphate (DMAPP) 1 and isopentenyl diphosphate (IPP) 2. The

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• transfer reagents in organic synthesis [1][2][3][4][5][6][7][8][9][10][11]. A 3-center 4-electron bond connects the central iodine atom, providing two electrons, with two carbon- or heteroatom ligands L1 and L2, providing one electron each (Figure 1). These ligands can be arranged along the hypervalent

• Supporting Information File 1) were observed at remarkable high Tpeak values (193.9–210.1 °C). Following these results, it has been intriguing to analyze the influence of the heteroatom in the heterocyclic moiety on the thermal decomposition process. The change of one nitrogen atom to sulfur as in thiazole

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• achieved using Et3N·3HF as the fluorine source with a high catalyst loading (20–30 mol %) affording the products in 45–92% yield [70]. The heteroatom-containing functional group (R1) is necessary for good reactivity and regioselectivity. α-Fluorination of acidic carbonyl compounds: In 2011, Shibatomi and

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• throughout this article [34]. Generic structures of commonly referenced heteropentafulvenes, named according to the heteroatom substitution: oxafulvene, azafulvene, phosphafulvene, thiafulvene and silafulvene. A representation of HOMO–LUMO orbitals of pentafulvene and the influence of EWG and EDG

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• [1][2][11][12]. Moreover, the designed macrocycles are useful molecular tools in the investigation of supramolecular catalysis and reaction mechanisms [1][2][13][14][15][16]. Heteracalixaromatics or heteroatom-bridged calix(het)arenes [17][18][19][20][21] are synthetic macrocycles composed of

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• , inexpensive, water-tolerant Lewis acid catalyst in the formation of both carbon–carbon and carbon–heteroatom bonds, and thereby the formation of various biologically promising organic compounds [68]. Important advances in scandium-catalyzed chemistry include [4 + 2] and [2 + 2] cycloaddition reactions, Baeyer

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

• Manuel Pedrón,
• Laura Legnani,
• Maria-Assunta Chiacchio,
• Pierluigi Caramella,
• Tomás Tejero and
• Pedro Merino

Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158

• by a mesomeric effect of the α-heteroatom. Nevertheless, the corresponding IRCs for the three transition structures confirmed a concerted reaction connecting the corresponding encounter pairs EP1, EP2 and EP3 (see Supporting Information File 1), formed from reagents R1–3 and ruthenium(IV) tetroxide

• ]. Table 1 summarizes the differences observed in the studied cases. The presence of a heteroatom contributes to lower the energy barrier of the oxidation reaction, and in the case of the pyrrolidine, it is below the reactant, demonstrating the stabilizing effect of the heteroatom in the transition

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• species E1 (δ 53 ppm) and E2 (δ 43 ppm). This difference may reveal that phosphorus in cation E4 is bound to a carbon atom, rather than to a heteroatom O or N, like in E1 and E2. Structurally close six-membered ring cations, having the C–P bond, resonate at 30.5–31.9 in 31P NMR [16], that is close to the

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• (Figure 2b), because a completely flat geometry of the isolated molecule DST 3 (in the gas phase) was obtained from theoretical calculations (vide infra). Molecules of DST 3 order in a typical herringbone fashion, where the terminal hydrogen atoms form hydrogen bond-like C–H heteroatom interactions (2.819

• heterotriacenes 1–4 evidenced only a slight increase of the interring bond (C4–C4’) for DTS 2 (1.43 Å) and consequently a smallest bite angle (C1YC1’ = 100°) despite the longest C–Se bond in the series (1.88 Å). The C-heteroatom distances vary for S (1.73–1.75 Å) to Se (1.85–1.88 Å) with the peculiarity that the

• ), the transition energies of S1 and S2 as well as the experimentally determined energy gaps are depicted for the heterotriacenes under investigation. The dependence of both transitions energies on the heteroatom character of the triacenes is shown. Both transitions gradually bathochromically shift from

Genomics-inspired discovery of massiliachelin, an agrochelin epimer from Massilia sp. NR 4-1

• Jan Diettrich,
• Hirokazu Kage and
• Markus Nett

Beilstein J. Org. Chem. 2019, 15, 1298–1303, doi:10.3762/bjoc.15.128

• these, six could be attributed to a 2,3-substituted phenol moiety (C-1 to C-6), whereas the other two carbons exhibited resonances at 181.3 ppm (C-23) and 182.3 ppm (C-12) characteristic of carbon–heteroatom double bonds. This left two degrees of unsaturation for additional ring structures. HMBC and

Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation

• Yang Liu,
• Julie Oble and
• Giovanni Poli

Beilstein J. Org. Chem. 2019, 15, 1107–1115, doi:10.3762/bjoc.15.107

• past decades, palladium chemistry has gained an important place in the toolbox of chemists, and its use became a privileged strategy for the selective formation of carbon–carbon and carbon–heteroatom bonds [2][3][4][5]. Among the different types of palladium-catalyzed transformations, domino – alias

Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction

• Vaida Milišiūnaitė,
• Rūta Paulavičiūtė,
• Eglė Arbačiauskienė,
• Vytas Martynaitis,
• Wolfgang Holzer and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2019, 15, 679–684, doi:10.3762/bjoc.15.62

• synthetic methods has been developed for the construction of carbon–heteroatom bonds using these types of catalysts. For example, the gold(I) catalyst [(Ph3PAu)3O]BF4 was applied in the regioselective intramolecular cyclization of alkynols to construct bicyclic ethers [37], while the silver(I) catalyst

Design of indole- and MCR-based macrocycles as p53-MDM2 antagonists

• Constantinos G. Neochoritis,
• Maryam Kazemi Miraki,
• Eman M. M. Abdelraheem,
• Ewa Surmiak,
• Tryfon Zarganes-Tzitzikas,
• Beata Łabuzek,
• Tad A. Holak and
• Alexander Dömling

Beilstein J. Org. Chem. 2019, 15, 513–520, doi:10.3762/bjoc.15.45

• bear a heteroatom in the 4-position as oxygen or sulfur (Y = O, S, Scheme 2) were employed in order to enhance the diversity of our macrocycles [4]. Thus, in a parallel way, we readily synthesized 12 different amino acids which were subsequently subjected to the Ugi macrocyclization. After quite some

• size of 15–17 atoms and an oxygen as the heteroatom linker improves the binding affinity. All the active macrocycles have a 6-chloro-substituted indole core. It is well established that at the bottom of the Try23 pocket a hydrophobic small subpocket exists which is formed by Phe86, Ile103, Leu82 and

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• organic chemistry because they can install polar functional groups onto simple non-polar alkene moieties. Many of the most common methods for these reactions rely upon the reactivity of pre-oxidized electrophilic heteroatom donors that can often be unstable, explosive, or difficult to handle. Herein, we

• describe a method for alkene oxyamination and diamination that utilizes simple carbamate and urea groups as nucleophilic heteroatom donors. This method uses a tandem copper–photoredox catalyst system that is operationally convenient. The identity of the terminal oxidant is critical in these studies. Ag(I

Synthesis and biological activity of methylated derivatives of the Pseudomonas metabolites HHQ, HQNO and PQS

• Sven Thierbach,
• Max Wienhold,
• Susanne Fetzner and
• Ulrich Hennecke

Beilstein J. Org. Chem. 2019, 15, 187–193, doi:10.3762/bjoc.15.18

• , its isolation should be possible and enable further modification, for example by ipso-substitution with heteroatom electrophiles. The application of the boronic acid in Suzuki–Miyaura coupling should also be possible [30][31]. Growth inhibition experiments against S. aureus showed that HQNO