Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• –Miyaura coupling reaction starting from 6,7-dibromo-2,3-dicyanonaphthalene, which was prepared according to the literature [45] (Scheme 2). The compounds with the substituents R = H [46] and t-Bu [47] are already known and were herein investigated for comparative purpose. The standard reaction conditions

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• preparing a heterogeneous Cu-based catalyst, the thereby obtained catalyst displayed remarkable performance in the Glaser hetero-coupling reaction. Combining two successful attempts, a further study concerning improvement of the robustness of catalysts and active sites when using LS as support is urgently

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• phosphoramidite building block 9 (Scheme 2). Results and Discussion Typically, the synthesis of C8-alkynyl derivatives relies on C8-bromoadenosine as reactant for the Sonogashira cross-coupling reaction to introduce the amino linker N-(propyn-2-yl)-6-(trifluoroacetamido)hexanamide (L) bearing an alkynyl moiety

Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides

• Dongsik Yang,
• Hongjian He and
• Bing Xu

Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221

• synthesis (SPPS) [47] to produce the peptides shown in Scheme 1. We first synthesized the peptide segments (i.e., Fmoc-DEDDDLLIG (1a) and acetyl-DEDDDLLIG (2a)). We kept the tert-butyl protecting groups of aspartic acid for the coupling reaction with Nap-ffky. We used 2,2,2-trifluoroethanol (TFE) in

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• obtained in a similar fashion by using (R)-lipoic acid in the coupling reaction. The ligand 2 contained a peripheral 2,2'-dipicolylamine residue for zinc(II) coordination. This group was separated from the lipoic acid anchor group by a C12 chain to ensure that it had a sufficient distance from the

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• , gave the corresponding β-brominated thienothiophene 4 in 91% yield [6]. Compound 4 was selectively brominated in α-position by using NBS in DMF at room temperature to give dibrominated thienothiophene 5 in 92% yield which was coupled in a Negishi-type cross-coupling reaction with zincated 2,3

• the azide route. The synthesis started from the above mentioned brominated thieno[3,2-b]thiophene 3, which was coupled with zincated 2,3-dibromothiophene 6 in a Negishi-type cross-coupling reaction with Pd(dppf)Cl2 as catalyst to give thiophene-substituted thienothiophene 10 in 72% yield. In the next

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0E9, Canada 10.3762/bjoc.16.201 Abstract In this report, chitin and chitosan nanocrystals were used as biomass-based supports for Pd nanoparticles (NPs) used as a heterogeneous catalyst for the Heck coupling reaction. By using a

• deposit Pd NPs directly onto both ChNCs and ChsNCs, and the as-made heterogeneous catalysts were tested with the Heck coupling reaction as a model for catalytic activity. Findings The fabrication of ChNC and ChsNCs was conducted using a procedure previously reported by our group (Lam) (see Supporting

• organic solvents (4:1 DMF/H2O) [26]. Conclusion ChNCs and ChsNCs were explored as sustainable supports for immobilizing Pd NPs to fabricate heterogeneous catalysts for the Heck coupling reaction. Through TEM and XPS analysis, metallic Pd NPs were formed and dispersed on the surface of the supports, while

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• 1,3,5-tris(bromomethyl)benzene (3) using the flash vacuum pyrolysis (FVP) technique as a key transformation (Scheme 1) [30]. As can be seen from an inspection of Scheme 1, they began their journey with the coupling reaction of 3 with 3-butenylmagnesium bromide in the presence of dilithium

• % yield. Next, the methyl substituents were introduced at the position of the carbonyl groups of 23 to generate the methyl-substituted olefin derivative 25 via alkenyl phosphates 24 by means of three-fold cross-coupling reaction with methylmagnesium iodide in THF. Finally, during the tandem ROM–RCM, they

• energy level and hence may be gifted to achieve a large open-circuit voltage. To this context, Amaya et al. has developed a novel bissumanenylidene 47 starting from the parent sumanene (2) first by converting it into the monoketosumanene followed by McMurry coupling reaction (Scheme 9). Although, they

Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst

• Jannis Ludwig,
• Julian Helberg,
• Hendrik Zipse and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179

• the Suzuki cross-coupling reaction published for a similar system [30], decomposition products and only 25% yield were obtained. Optimization by lowering the reaction temperature increased the yield to 91% (Scheme 1). Switching properties of porphyrin 1 Preliminary investigations on the photochemical

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• compared to the IC50 values of 1.3, 1.0, and 0.36 nM, respectively, for spliceostatin A (4) against the same cell lines. Fragment union via Pd-catalyzed sp2–sp2 coupling A Negishi coupling reaction [42] was used in the Jacobsen synthesis of FR901464 (1, Scheme 23) [17][18]. The hydrozirconation of 91

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• thiazolopyrimidine-5-ones by reacting 6-methyl-2-thiouracils with bromoethynylketones has been reported by Shishkin and co-workers (Scheme 4) [20]. The authors for the first time proved the structure of the 5-oxo isomer by single crystal X-ray diffraction analysis. The Pd-catalyzed Sonogashira coupling reaction

• ]thiazol-2-yl)-2-(7-R-5-oxo-5H-thiazolo[3,2-a]pyrimidin-3-yl)acetonitriles. Synthesis of 3-acyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-ones. Sonogashira coupling reaction of 6-amino-2-thiouracil with propargyl bromide. Reactions of 6-substituted 2-thiouracils 1a,b with chloroethynylphosphonates 2a–c

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• -bromobenzoate (6) to form methyl 4-benzylbenzoate (7) was used to evaluate the activity of the palladium catalysts on polymer support (Scheme 2). The Negishi reaction is a potent cross-coupling reaction in organic chemistry. Notably, it has much value for the synthesis of fine chemicals and medicinal drugs [22

One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes

• Haruyasu Asahara,
• Minami Hiraishi and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2020, 16, 1830–1836, doi:10.3762/bjoc.16.150

• group hinder the electrophilic modification at the 3-position. Generally, the aryl group is introduced by a Suzuki–Miyaura cross-coupling reaction [4][5], for which 3-bromo-4-nitrophenol must be prepared by the nitration of 3-bromophenol [6][7]. An alternative approach is the nitration of 3-arylphenol

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• with the complexity of its structures [11][19][20][21][22][23][24][25][26][27]. The intramolecular Heck arylation coupling reaction is among the most useful strategies for the construction of these compounds (Scheme 1) [11][21]. For example, isoindolo[2,1-a]indoles 6 have been prepared by the

• -polycyclic structures [42], we herein combined both approaches shown in Scheme 1 to design the construction of pentacycles 11, after carrying out an uncommon but highly diastereoselective Diels–Alder cycloaddition followed by a coupling reaction. This route also allowed out the aromatization of the B ring to

• intramolecular Heck cross-coupling reaction of the octahydroindoles 9/10 to the pentacycles 11, the process was explored with the simple substrates 8c,d and 8g (Scheme 4). Thus, the Pd(0)-catalyzed cyclization of the latter vinylpyrroles with potassium acetate and using acetonitrile or dimethylacetamide (DMA) as

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• (products 46a,b, 46m,n), 1,3-diketones (product 46r), as well as lactones (products 46o–q) were used in the oxidative C–O coupling reaction. The coupling of oximes with 1,3-diketones proceeded in lower yields than with 1,3-ketoesters (products 46a and 46r). Despite the presence of t-BuOOH in the system, a

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• 87% yield) was investigated (Scheme 8) [52]. Finally, the Poisson’s group developed a methodology for the Ullman cross-coupling reaction between the in situ-generated CuCF2PO(OEt)2 and aryl iodides containing a coordinating group (e.g., CO2CH3, COCH3, NO2), at the ortho-position of the halide [52

• (0)-mediated reductive cross-coupling reaction between the iodobenzene and various 2-bromo-1,1,2,2-tetrafluoroethyl derivatives (RCF2CF2Br) was developed presumably involving a RCF2CF2Cu species (Scheme 21) [76]. In 2015, Yagupolskii and co-workers investigated the synthesis of perfluoroalkylcopper

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• )-iodoalanine 2. The reaction was activated using Pd(0) as a catalyst. A palladium-catalyzed cross-coupling reaction between an organozinc iodide and aryl halides offers a convenient method for the direct preparation of protected fluorinated Phe analogues 3. Thus, cross coupling of the protected iodoalanine 2

• the protected ᴅ,ʟ-N-Boc-2-bromophenylalanine (89) using a Stille coupling reaction to give the o-vinyl derivative 90 as key intermediate. A hydroboration reaction of compound 90 afforded the primary alcohol 91, which was directly fluorinated and deprotected to give the free amino acids 93 (ᴅ and ʟ

Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

• Yongsu Li,
• Bendu Pan,
• Xuefeng He,
• Wang Xia,
• Yaqi Zhang,
• Hao Liang,
• Chitreddy V. Subba Reddy,
• Rihui Cao and
• Liqin Qiu

Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85

• not so good (see Supporting Information File 1, Scheme S1, compounds 3u, 60% yield, 11% ee; 3v, 90% yield, 0% ee). More specifically, the change of the R1 group on the bromoamide compound has a weak influence on the coupling reaction. No matter it was a straight alkyl chain, a branched alkyl chain, a

• silica gel. The enantiomeric excess value of the product was determined by HPLC by using an AD-H, OD-H or IA-3 column. (R)-MeO-MOP and our ligands. Asymmetric Suzuki–Miyaura coupling. Reaction conditions: 1 equiv N-aryl-bromoaryl compounds, 2 equiv arylboronic acids, 5 mol % Pd, 6 mol % ligand, 3 equiv

• of K3PO4, 2 mL THF, 50 ⁰C, 72 h; Yields are combined isolated values; ee values were determined by HPLC with chiral columns. Asymmetric Suzuki–Miyaura coupling. Reaction conditions: 1 equiv of bromoaryl compounds, 2 equiv of arylboronic acids, 5 mol % Pd, 6 mol % of ligand, 3 equiv of K3PO4, 2 mL THF

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

• heterogeneous photocatalysts. A Sn porphyrin-based porous aromatic framework (SnPor@PAF) with a broad and strong optical absorption in the visible light region was used for this transformation [98]. Luo, Ji and co-workers synthesized this material by a Yamamoto homo coupling reaction using a well-designed

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• cycle for the C–C coupling. The coupling reaction follows a radical–anion mechanism due to the presence of electron-donating ligand 12 and this is the key feature allowing preferential binding of the phenoxyl radicals for PCET. Products arising from homo- and heterocouplings were formed with high

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• excellent yields. However, benzyl and vinyl bromides did not prove efficient for this coupling reaction. Common cyclic and acyclic ethers, symmetric or nonsymmetric, such as oxetane, tetrahydropyran, dioxane, 2-methyltetrahydrofuran, and 2-methoxy-2-methylpropane, were found compatible, affording the

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• material was purified via column chromatography using silica gel. The BODIPY dimer 7 was prepared using 6 [38] and was obtained as a fluorescent orange solution or as pink-orange crystals in a 30% yield. Similarly, the Pd-catalyzed Sonogashira cross-coupling reaction [39] was successful for the reaction

• confirm full conversion. For this reason, it may be that the ethynyl bond was not completely deprotected before the next coupling reaction. After the TBAF deprotection step, the second Sonogashira cross-coupling reaction was carried out with the nickel porphyrin 15 [41] under the same reaction conditions

• bromination of 17a [42] (Scheme 3). The coupling reaction was initially carried out with (5,15-dibromo-10,20-dihexyl/diphenyl)porphyrinato)zinc(II) but both porphyrins had extremely low solubility. Using the more soluble 17c gave access to the triptycene–porphyrin–triptycene complex 18. The reaction was