Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• groups to form biaryl frameworks. Traditionally, transition-metal-catalyzed cross-coupling reactions of aryl halides or pseudohalides with arylmetal reagents have been employed for the connection of two aryl units [5][6][7][8][9]. However, in search of more efficient synthetic routes, C–H arylation

Copper-catalyzed remote C–H arylation of polycyclic aromatic hydrocarbons (PAHs)

• Anping Luo,
• Min Zhang,
• Zhangyi Fu,
• Jingbo Lan,
• Di Wu and
• Jingsong You

Beilstein J. Org. Chem. 2020, 16, 530–536, doi:10.3762/bjoc.16.49

• molecules, thus having drawn much attention. Transition metal-catalyzed C–X/C–M cross-coupling reactions such as Suzuki and Stille couplings are the main approaches to achieve the arylation of PAHs [7][8][9][10][11]. However, the selective arylation of the C7-position of 1-naphthoic acid derivatives remains

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• phosphole oxides through C–H functionalization and cross-coupling reactions. The phosphole ring was constructed in the early stage of the synthesis by a three-component assembly method featuring a 1,4-cobalt migration as the key step. Unlike other C–H activation/alkyne annulation approaches to benzo[b

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• to synthesize thiazolidinone derivatives through a Barton–McCombie pathway in 2015 [17] (Scheme 1b). Recently, potassium tert-butoxide has been shown to be an efficient promoter for C–C-bond formation reactions [18][19][20][21][22]. However, only few reports described C–N-bond cross-coupling

• reactions using potassium tert-butoxide as promoter. Wu developed an efficient protocol for the KOt-Bu-promoted synthesis of 1-aminoisoquinolines from 2-methylbenzonitriles and benzonitriles [23], and the carbonylative cyclization of propargylic amines with selenium under CO gas-free conditions [24]. Based

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• obtained in excellent yields of 93% and 97%, respectively, and represent potential substrates for subsequent cross-coupling reactions, which would provide structurally more complex products. Amidines with heterocyclic substituents were also evaluated. While the pyridine-substituted derivative 10o furnished

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• could be trifluoromethylselenolated that way (Scheme 2) [13][15][16][17]. Mechanistically, the authors postulated the involvement of copper(I)/(III) oxidation states. Oxidative cross-coupling reactions between terminal alkynes using the [(bpy)CuSeCF3]2 complex were also undertaken by the same group to

• yields, as can be seen in Scheme 12 [35]. Due to the limitations of ClSeCF3 as an electrophilic reagent for trifluoromethylselenolations in cross-coupling reactions, our group developed a new bench-stable reagent, namely trifluoromethyltolueneselenosulfonate (TsSeCF3) [36

• already demonstrated its versatility in numerous processes. Nevertheless, its use in oxidative cross-coupling reactions requires stoichiometric amounts of the oxidant, which limits the attractiveness of the method in some cases. Finally, the newly developed electrophilic reagent TsSeCF3 also demonstrated

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• summary, we developed an umpolung strategy for catalytically formed α-alkoxyalkyl anions from aromatic aldehydes for the use in allylic cross-coupling reactions. The synergistic palladium/copper-catalyzed reaction of aromatic aldehydes, allylic carbonates, and a silylboronate delivered the homoallylic

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• . Synthetic strategy towards 1,3,5-tris(arylazo)benzenes 3 based on consecutive Baeyer–Mills reactions. Preparation of tris(arylazo)benzenes 3 by Pd-catalyzed cross-coupling reactions of N-Boc-arylhydrazides and bromo-substituted ABs, followed by oxidation. Synthesis of azobenzene building block 8. Synthesis

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

• effectively tune their physical characteristics and also reduce production costs since the routine synthesis of heteroacene structures involves cross-coupling reactions catalyzed by expensive transition metals [15]. Thus, in this paper, we would like to present an efficient metal-free synthesis of the aryl

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• -coupling reactions was planned. Starting from 1-bromo-4-methoxynaphthalene (1), the Pd-catalyzed Suzuki coupling reaction with commercial boronic acids afforded the naphthyl and pyrenyl derived methyl ethers 2 and 3 in 78% and 87% yield, respectively (Scheme 1). For the synthesis of the anthryl derivative

• fluorescence response on fluoride ion addition. Results and Discussion Synthesis of the borylated dyes 16–19 For the synthesis of the triaryl systems 12–15, precursors of the organoboron dyes 16–19, the construction of two stereogenic axes was required. Therefore, a synthetic route based on consecutive cross

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• reactions). Conclusion Since just three literature examples are known to date in which Suzuki–Miyaura cross-coupling reactions gave access to silicon rhodamines in poor to moderate yields (Scheme 2), we wanted to improve these first valuable experimental results. In general, the amount of re-isolated

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• with chlorophosphines, the reaction of metal phosphides with haloalkanes, and transition-metal-catalyzed cross-coupling reactions to form C–P bonds are the most widely used methods for the synthesis of phosphines [13][14]. Since phosphines are easily oxidized to phosphine oxides, the addition of

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• , phenolates), acyl anions (generated by umpolung of aldehydes with imidazolium salts) and by palladium-catalyzed cross-coupling reactions (Suzuki, Stille) [10]. A related Stille cross coupling of a benzo[c][2,7]naphthyridine bearing a triflate group at C-5 gave an intermediate for the total synthesis of

• of the 4-bromo residue (cross-coupling reactions, nucleophilic substitutions) should open the opportunity to generate a broad variety of 4,5-disubstituted benzo[c][2,7]naphthyridines as building blocks for natural products total synthesis (Figure 2D). Results and Discussion For the envisaged direct

• cross-coupling reactions, 4-bromo-5 iodobenzo[c][2,7]naphthyridine (13) is regarded as an interesting building block for synthetic chemists. Another interesting building block is ester 14, which was obtained in 37% yield by quenching 5-metalated 9d with diethyl carbonate. The quenching of 9d after

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• useful tools in the further investigation of the biochemistry and pharmacology of sirtuins. Results Chemistry of azastilbenes All azastilbene derivatives were synthesised by palladium-catalysed cross-coupling reactions using either commercially available 5-bromonicotinamide (3a) or methyl 5

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

• oxidation states (Cu(0), Cu(I), Cu(II), and Cu(III)). Copper has been known for a long time to act as a catalyst for cross-coupling reactions (Ullmann–Goldberg reaction), cyanation of aryl halides (Rosenmund–von Braun reaction), Hurtley reaction and intermolecular oxidative cyclization of haloalkynes [41

• ][42][43][44]. Various copper salts have been used as Lewis acid in homogeneous catalysis. CuO nanoparticles (NPs) were used for C–N, C–S, C–O cross-coupling reactions and C-arylation. Recently, exploiting the cross-coupling tendency of CuO NPs, Reddy et al. have reported their use as a heterogeneous

• -catalyzed cross-coupling reactions have laid down the foundation of new C–C bond formations [50][51]. A number of Pd-catalyzed organic reactions viz., C–N coupling, amination and intramolecular amidation, cyclization, and Suzuki–Miyaura coupling [52][53][54][55] have recently been reported in the literature

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• -coupling reactions. Herein, stereodefined 1,3-enynes, including tetrasubstituted ones, were straightforwardly synthesized from cis or trans-alkynylated oxiranes in good to excellent yields by a one-pot cascade process. The procedure relies on oxirane deprotonation, borylation and a stereospecific

• .15.141 Abstract 1,3-Enynes are important building blocks in organic synthesis and also constitute the key motif in various bioactive natural products and functional materials. However, synthetic approaches to stereodefined substituted 1,3-enynes remain a challenge, as they are limited to Wittig and cross

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

• different scan rates (right). Synthesis of heterotriacenes DTT 1 and DTS 2 via copper-catalyzed cross-coupling reactions. Synthesis of selenolotriacenes DST 3 and DSS 4. Oxidative polymerization of heterotriacenes 1–4 to corresponding conjugated polymers P1–P4. Bond distances, bond angles, and distances D

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• -4,7-diiodo-2,1,3-benzothiadiazole (11b) was reported by Blakey, Marder and co-workers [51], no cross-coupling reactions using this derivative have been reported yet. Recently, the synthesis of 4,7-dibromo-5,6-dicyano-2,1,3-benzothiadiazole (11a) was also reported alongside with its use in a

• moments known for MOF linkers so far, with 5 even exceeding 10 Debye. Cross-coupling reactions, particularly Sonogashira reactions of dicyanobenzenes are known to be accompanied by phthalocyanine formation and other side products. These problems are avoided by applying Stille conditions using 1

Remarkable effect of alkynyl substituents on the fluorescence properties of a BN-phenanthrene

• Alberto Abengózar,
• David Sucunza,
• Patricia García-García and
• Juan J. Vaquero

Beilstein J. Org. Chem. 2019, 15, 1257–1261, doi:10.3762/bjoc.15.122

• -phenanthrenes with substituents of a diverse nature have been synthesized by palladium-catalyzed cross-coupling reactions of a common chloro-substituted precursor, which was made from readily available materials in only four steps. Evaluation of the photophysical properties of the prepared compounds unveiled an

• cross-coupling reactions [30], and we envisioned that this reaction could be used to prepare C7 substituted BN-phenanthrenes (Figure 1). Herein we report the synthesis of chloro-substituted BN-phenanthrene 1b, its derivatization via palladium-catalyzed cross-coupling reactions and the significant effect

• to provide alkynyl-substituted BN-phenanthrenes 1e and 1f in excellent yields (Scheme 3). These results confirm the value of palladium-catalyzed cross-coupling reactions of chloro-substituted BN-arenes as a useful tool for the preparation of derivatives functionalized with a range of substituents of

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• ]. We also disclosed for the first time in 2007 the synthesis of tricyclopropylbismuth (24) and its use in N-cyclopropylation [35], palladium-catalyzed cross coupling [36] and carbonylative cross-coupling reactions [37]. Recently, we demonstrated that tricyclopropylbismuth (24) can be used to S

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• -Crafts alkylations [5], cross-coupling reactions [6] and cyclotrimerizations [7], to amine-based chemistry with Schiff base reactions [8], imidisation, and amidisation reactions [9]. In the recent past, a strong focus was also set on the development of HCPs (hyper-crosslinked polymers) [10]. Typically

Heck- and Suzuki-coupling approaches to novel hydroquinone inhibitors of calcium ATPase

• Robert J. Kempton,
• Taylor A. Kidd-Kautz,
• Soizic Laurenceau and
• Stefan Paula

Beilstein J. Org. Chem. 2019, 15, 971–975, doi:10.3762/bjoc.15.94

• at C-8 of TG, replacing the natural butanoyl group at that position with an ester moiety terminating in a primary amine. Here, we describe our efforts to use transition metal cross-coupling reactions (Suzuki [10] and Heck [11]) to modify BHQ with a side chain terminating with a free primary amine

• that could serve as an attachment point for a peptide group (see 1b above). We had anticipated that the availability and versatility of cross-coupling reactions would allow for the introduction of side chains of varying lengths and functionalities [10]. In this paper, we report on the synthesis of 14

• more accessible bromo analogue 5a in cross-coupling reactions. Heck cross coupling [15] of 4a and 5a with acrylonitrile in the presence of Pd2(dba)3, [(t-Bu)3PH]BF4 and Cy2NCH3 in dioxane, following the procedure of Fu [16][17], gave the coupled products 6 and 8, respectively, in yields of 89% and 82

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• ) derivatives and dipeptides. In this regard, trimerization and Negishi cross-coupling reactions are used as the key steps starting from readily available 4’-iodoacetophenone and L-serine. These C3-symmetric molecules containing AAA moieties are useful to design new ligands suitable for asymmetric synthesis and

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• , trifluoromethyl and ester, gave 75–95% yields of the corresponding products y-9–y-13, which were precursors for further transition metal-catalyzed cross-coupling reactions. To further explore the generality of this reaction, different substituted ortho-bromobenzoyl chlorides were then tested (Scheme 3). The ortho

Silanediol versus chlorosilanol: hydrolyses and hydrogen-bonding catalyses with fenchole-based silanes

• Falco Fox,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2019, 15, 167–186, doi:10.3762/bjoc.15.17

• , BIFOL, Figure 1) [52][54] and it´s derivative, the chiral chlorophosphite ligand 6 (BIFOP-Cl, Figure 1), e.g., in Cu-catalyzed 1,4-additions [53], in Pd-catalyzed alkyl–aryl cross coupling reactions [55][56], as well as for organoaluminum fencholate reagents [57]. Unexpected stability against hydrolysis