Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• against Gram-positive bacteria and compound 3ck against C. albicans were better than the reference drug norfloxacin. Keywords: acceptorless dehydrogenative coupling reaction; antibacterial; cyclometalated iridium complexes; quinolines; Introduction As an important class of heterocyclic compounds

Microelectrode arrays, electrosynthesis, and the optimization of signaling on an inert, stable surface

• Kendra Drayton-White,
• Siyue Liu,
• Yu-Chia Chang,
• Sakashi Uppal and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2022, 18, 1488–1498, doi:10.3762/bjoc.18.156

• peptide so that the thiol group in the sidechain could be used to place the molecule the array with the use of an electrochemically initiated Cu(I)-catalyzed cross-coupling reaction (Scheme 1) [9]. To this end, the Cu(I) catalyst needed for the reaction was generated at the electrodes by the reduction of

• for the confinement strategy to keep up. The result is a loss in confinement. It is important to point out that the reaction shown in Scheme 1 is not a typical electrosynthetic reaction. The cross-coupling reaction shown is a Cu(I)-catalyzed transformation that requires no recycling of a reagent

• direct analogy to the RGD-peptide experiment shown above. In this case, a Cu(II)-mediated Chan–Lam coupling reaction was used to place each molecule on a arylborate ester coating the array (Scheme 2) [23]. The Cu(II) needed for the transformation was generated at the selected electrodes by the oxidation

Synthesis of meso-pyrrole-substituted corroles by condensation of 1,9-diformyldipyrromethanes with pyrrole

• Baris Temelli and
• Pinar Kapci

Beilstein J. Org. Chem. 2022, 18, 1403–1409, doi:10.3762/bjoc.18.145

• the silica column to remove Cu(OTf)2. The solvent was removed under reduced pressure and the crude product was purified by flash column chromatography over silica gel with CH2Cl2/hexane (1:1). Synthesis of 3 and 4 by [2 + 2] MacDonald coupling reaction A solution of 5-phenyl-1,9-diformyldipyrromethane

Preparation of an advanced intermediate for the synthesis of leustroducsins and phoslactomycins by heterocycloaddition

• Anaïs Rousseau,
• Guillaume Vincent and
• Cyrille Kouklovsky

Beilstein J. Org. Chem. 2022, 18, 1385–1395, doi:10.3762/bjoc.18.143

• (Scheme 6); iodination with NIS, as previously described [29], gave lower yields. We first attempted the coupling with the terminal alkyne 19, anticipating the possibility of reducing the triple bond after coupling reaction. In agreement with literature precedents, we chose LiHMDS for deprotonation of 19

• gave a reproducible 46% yield of 23. Optimal conditions were obtained using 1.8 equivalents of vinyl iodide and 1.7 equivalents of BuLi (Table 2, entry 6). It was difficult at this stage to determine the stereoselectivity of the coupling reaction since the starting acetal in 20 was a mixture of

• stereoselectivity of the coupling reaction. This validates the overall strategy for the synthesis of leustroducsins or phoslactomycins by the synthesis of a central cyclic core and its coupling with the other fragments. Conclusion We have synthesized an advanced intermediate for the total synthesis of

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• a narrower residence time distribution and higher yields (see Table 2). C–O coupling reaction Finally, we evaluated the use of the capillary-based reactor for the related C–O coupling of 4-iodobenzotrifluoride and N-(Boc)-proline with N-tert-butylisopropylamine (BIPA) in dimethyl sulfoxide (DMSO

Electrochemical formal homocoupling of sec-alcohols

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masashi Shiota,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

• -coupling reaction of two different benzyl alcohols (Scheme 3). Pleasingly, the reaction using a 1:1 mixture of 1a and 1f under the standard reaction conditions provided the cross-coupling product 2af (dr = 94:6) together with the homocoupling products 2a and 2f. To demonstrate the scalability of the

• /mol, 0 °C, under air. a100 mA cc. b6 F/mol, imidazole (0.075 equiv). c6 F/mol. d8 F/mol, imidazole (0.1 equiv) e8 F/mol, MeCN/MeOH (4:1, 5 mL) without H2O. Investigation of cross-coupling reaction. Large-scale experiment. Control experiments. aDetermined by 1H NMR using 1,3,5-trimethoxybenzene as an

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes

• Mio Matsumura,
• Kaho Tsukada,
• Kiwa Sugimoto,
• Yuki Murata and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 863–871, doi:10.3762/bjoc.18.87

• selenides [25]. In this reaction, unlike the former, bis(imidazo[1,2-a]pyridin-3-yl) diselenides are generated through C–H selenation at the 3-position of 2-arylimidazopyridines with Se powder, followed by the cross-coupling reaction between diselenides and triarylbismuthines. These one-pot reactions are

• imidazopyridinyl selenides A Cu-catalyzed cross-coupling reaction using benzene ring substituted diaryl diselenides with terminal alkynes in the presence of bases is effective for synthesizing aryl alkynyl selenides [27][28][29][30][31]. We previously reported a simple method for the synthesis of bis(2-arylimidazo

• standard conditions did not proceed (Scheme 1, reaction 2). The reaction mechanism for this coupling reaction is presently unclear. We propose that the reaction mechanism may be similar to that of the C(sp)–Se bond formation of terminal alkynes with diaryl diselenides reported by Stieler and Schneider [31

Continuous flow synthesis of azobenzenes via Baeyer–Mills reaction

• Jan H. Griwatz,
• Anne Kunz and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2022, 18, 781–787, doi:10.3762/bjoc.18.78

• used Baeyer–Mills coupling reaction was adopted to a continuous flow setup. The versatility was demonstrated with a scope of 20 substances and the scalability of this method exemplified by the synthesis of >70 g of an azobenzene derivative applied in molecular solar thermal storage (MOST) systems

DDQ in mechanochemical C–N coupling reactions

• Shyamal Kanti Bera,
• Rosalin Bhanja and
• Prasenjit Mal

Beilstein J. Org. Chem. 2022, 18, 639–646, doi:10.3762/bjoc.18.64

• -Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a commonly known oxidant. Herein, we report that DDQ can be used to synthesize 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-ones via the intra- and intermolecular C–N coupling reaction under solvent-free mechanochemical (ball milling) conditions. In

• , followed by hydride abstraction to generate the desired product 2a. On the other hand, the formation of quinazolin-4(3H)-ones starts with the formation of an imine intermediate and then it will follow the similar mechanistic pathway. To explore the synthetic utility of the oxidative C–N cross-coupling

• reaction, we have performed the large-scale synthesis under the solvent-free (ball milling) conditions as shown in Figure 6. In this context, milling of the substrate (E)-N-(2-((4-bromobenzylidene)amino)phenyl)-4-methylbenzenesulfonamide (1c, 2.795 mmol) in the presence of 1.2 equiv of DDQ delivered 1.098

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• of aryl moieties into methylthio-substituted nitrogen heterocycles such as tCBz-mPYR are a Ni(0)-catalyzed cross-coupling reaction with Grignard reagents [34][36] or the Liebeskind–Srogl reaction employing arylboronic acids [37][38][39]. Taking into account a large assortment of arylboronic acids and

• the simplicity of the method, we chose the Liebeskind–Srogl cross-coupling reaction for the synthesis of the target 2-arylpyrimidine derivatives. Thus, heating tCbz-mPYR with phenyl-, 4-cyanophenyl-, 3-cyanophenyl-, or 3-bromophenylboronic acid at 130 °C in dioxane in the presence of Pd(PPh3)4, copper

Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• derivatives may be metalated in a Li–halogen exchange reaction [27]. In another versatile approach, arylation and alkenylation reactions of the norbornadiene may be accomplished with a Suzuki–Miyaura coupling reaction. In this case, halogenated norbornadienes react with arylboronic acids or their esters to

• (HRMS). To assess the suitability of the boronic esters 2a and 2b to be used as building blocks in Suzuki–Miyaura reactions, the Pd-catalyzed cross-coupling reaction of norbornadiene 2a and bromobenzene (4a) was examined under different conditions (Table 1, Scheme 2). First experiments were conducted

• coupling reaction of 2a with 4a gave the product 5a in only 37% yield (Table 1, entry 6). The use of PdCl2(dppf)·CH2Cl2 as catalyst with different bases resulted in even lower yields (≤15%; Table 1, entries 2–4). In contrast, the best yield was accomplished with Pd(PPh3)4 as catalyst and NaOH as base in

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

• Sangram Gore,
• Sundarababu Baskaran and
• Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

• replacement of organic solvents. The melts are stable against air and have very low vapor pressures resembling the properties of ionic liquids. In addition, the polarity of these melts is very high [33]. Recently, we have explored several organic transformations such as coupling reaction, cycloaddition

Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• intermediate spontaneously turns into the carbanion C, thus realizing the imine umpolung and allowing the cross-coupling reaction with the remaining electrophilic ketimine 1. The complete diastereoselectivity would arise from the mutual approach of the two oxindole nuclei from the less hindered side, that is

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• [2]. Over the past 15 years, there has been a growing interest in the Sonogashira coupling reaction, which is one of the most powerful methods for the formation of Csp2–Csp bonds leading to arylalkynes and conjugated alkenynes, which are often intermediates or precursors in the synthesis of natural

• importance of this coupling reaction [7]. Later, Sonogashira-type reactions requiring only copper as catalyst alone [8] and with other transition metals [9][10][11][12] have been reported. Especially iron has attracted a great deal of attention owing to its low price, easy availability, abundant nature, and

• for the effective Sonogashira coupling under aqueous conditions (Scheme 3) [22]. The coupling reaction was catalyzed by the nanoparticles in water between room temperature and 45 °C. Notably, the amount of Pd was below the detection limit. The reaction done in the presence of 1000 ppm of Pd ligated

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• lithium hydroxide monohydrate [29] to give the desired indole-2-acetic acid (14) in 95% yield. The peptide coupling reaction [30] of indole-2-acetic acid (14) and 2-iodoaniline afforded 15 in 23% yield (Scheme 3). Subsequent protection of both the indole and the amide nitrogen with tert-butyloxycarbonyl

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

• Thaipparambil Aneeja,
• Cheriya Mukkolakkal Abdulla Afsina,
• Padinjare Veetil Saranya and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

• oxidative cyanation of aza-Baylis–Hillman adducts. Synthesis of 1° alkyl nitriles using [Ru(bpy)3](PF6)2 as the photocatalyst. Synthesis of 2° and 3° alkyl nitriles using [Ru(bpy)3](PF6)2 as the photocatalyst. Photoredox cross coupling reaction. Synthesis of α-amino nitriles from amines via a one-pot

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• through this step were used in a well-stablished nickel-catalyzed cross-coupling reaction [19][27][28][29][30] with aryl bromides as a proof of concept, leading to the synthesis of aryl ketones. We also present computational calculations of the HAT reaction step with the DABCO radical cation as the

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• first Fe-catalyzed cross-coupling reaction between Grignard reagents and vinyl halides [37]. As of late, the development of Fe-catalyzed cross-coupling methodology and mechanistic rationales have burgeoned [38]. Today, the rate of growth within the field of iron catalysis is much greater than that

• functionalized compound (Scheme 1b). Lastly, the reaction between two C–H compounds to form a C–C bond, formally eliminating H2, hence the dehydrogenative reference (Scheme 1c). As this coupling reaction does not require functionalization prior to coupling, it shortens the synthetic route, and lowers the

• iron-catalyzed cross-coupling reactions of alkyl halides began in 2004 when Nakamura first reported the TMEDA-mediated Fe-catalyzed cross-coupling reaction between secondary bromides with aryl Grignard reagents [52]. Since then, several reports of alkyl halide cross-coupling reactions have been

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• sulfones is a valuable and appealing task in synthetic chemistry. Traditionally, diarylmethyl sulfones are synthesized by transition-metal-catalyzed deoxy C–S bond-coupling reaction of sodium arylsulfinates with diarylmethanols [11], C–H functionalization of alkyl sulfones with aryl halides [12], and via a

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• by Humber et al. [45]. They started with a coupling reaction of (+)-thiolactic acid 3p and 2-benzoyloxyacetaldehyde (3a) using boron trifluoride etherate. A diastereomeric mixture of oxathiolane acids 29 and 30 was prepared in a 1:2 ratio in good yield (Scheme 7). Further separation of the

• ammonolysis in methanol affords compound 1c. The silylation of 1c with TBDPSCl was carried out, and then coupling reaction with tert-Boc-Met-Leu-Phe-OH in the presence of DCC and HOBt provided compound 98. The tert-Boc protecting group was further removed in formic acid, and the resulting nucleoside peptide

Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

• Tomáš Chvojka,
• Athanasios Markos,
• Svatava Voltrová,
• Radek Pohl and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

• stereoselective outcome of the Suzuki cross-coupling reaction of various (Z)-β-enamido triflates (Scheme 1B). Results and Discussion We initiated our study by examining the Suzuki cross-coupling of vinyl triflate 1a and 3-nitrophenylboronic acid. First, the influence of the catalyst on the stereoselective outcome

Electrocatalytic C(sp³)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

• Bin Guo and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

• electrocatalytic dehydrogenative cross-coupling reaction of tetrahydroisoquinolines with terminal alkynes in continuous flow (Scheme 1D). These reactions require low loadings of supporting electrolyte and proceed through Cu/TEMPO relay catalysis without need for additional ligands. Results and Discussion The

• electrochemistry is an ideal tool for promoting dehydrogenative cross-coupling reactions as no external chemical oxidants are needed [11][12][13][14][15][16][17][18][19]. In this context, Mei and co-workers have reported an elegant TEMPO/[L*Cu] co-catalyzed asymmetric electrochemical dehydrogenative cross-coupling

• reaction of tetrahydroisoquinolines with terminal alkynes (Scheme 1C) [10]. The chiral ligand was found to be critical for the stereoinduction as well as product formation for these electrochemical reactions that are conducted in batch. Continuous-flow electrochemical microreactors offer several advantages

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• copper-catalyzed C–O cross-coupling reaction. Results of mechanistic studies indicated that in this case a CuI–phenoxide complex is a competent intermediate in the photoinduced C–O bond formation. In 2020, Nguyen and co-worker [90] reported copper-catalyzed C–O cross-coupling of glycosyl bromides with

• -base photocatalysis. Olefinic C–H functionalization and allylic alkylation. Cross-coupling of unactivated alkenes and CF3SO2Cl. Chlorosulfonylation/cyanofluoroalkylation of alkenes. Hydroamination of alkenes. Cross-coupling reaction of alkenes, alkyl halides with nucleophiles. Cross-coupling of alkenes

• . Aerobic oxidative C(sp)–S coupling reaction. Copper-catalyzed alkylation of carbazoles with alkyl halides. C–N coupling of organic halides with amides and aliphatic amines. Copper-catalyzed C–X (N, S, O) bond formation reactions. Arylation of C(sp2)–H bonds of azoles. C–C cross-coupling of aryl halides

Copper-catalyzed monoselective C–H amination of ferrocenes with alkylamines

• Zhen-Sheng Jia,
• Qiang Yue,
• Ya Li,
• Xue-Tao Xu,
• Kun Zhang and
• Bing-Feng Shi

Beilstein J. Org. Chem. 2021, 17, 2488–2495, doi:10.3762/bjoc.17.165

• -determining step. Conclusion To summarize, we have reported a copper-catalyzed direct ortho-C–H/N–H coupling reaction of ferrocenes with alkyl amines directed by 8-aminoquinoline. Fruitful mono-aminated ferrocenes were obtained in moderate to good yields and the mild conditions offered the possibility to the

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• ]. Then, they also reported another CuH-catalyzed coupling reaction of 1,3-enynes 54 and nitrile to prepare polysubstituted pyrroles 55 (Scheme 21) [66]. The substrates 54 could be easily prepared by Sonogashira coupling of terminal alkynes and vinyl halides. It is worth mentioning that the addition of

• to pyrroles. Au/Ag-catalyzed oxidative aza-annulation of 1,3-enynyl azides. The plausible mechanism of Au/Ag-catalyzed oxidative aza-annulation. Synthesis of 2-tetrazolyl-substituted 3-acylpyrroles from enynals. CuH-catalyzed coupling reaction of 1,3-enynes and nitriles to pyrroles. The mechanism of