A smart deoxyribozyme-based fluorescent sensor for in vitro detection of androgen receptor mRNA

• Ekaterina A. Bryushkova,
• Erik R. Gandalipov and
• Julia V. Nuzhina

Beilstein J. Org. Chem. 2020, 16, 1135–1141, doi:10.3762/bjoc.16.100

• transcription factor [8]. Among the target genes of the AR are genes encoding proteins involved in intracellular signal transmission, proliferation, as well as differentiation and apoptosis [9]. An increase of AR mRNA expression or enhancing their sensitivity to the corresponding ligands may lead to the

• random sequence molecules, also known as SELEX (systematic evolution of ligands by exponential enrichment), and was a holistic harpin [22]. In further work MGA was separated into two strands, and nucleic acid binding arms were added to each strand, allowing MGA to target a sequence of interest

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• . The design of MOFs is based on metal nodes linked by organic ligands whilst COFs have ligands joined by organic nodes. Both displayed great catalytic properties, sometimes exceeding those of homogeneous analogs [23][24]. Unfortunately, stability problems, the cost of the initial materials, and the

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• stereoisomer, despite the presence of two isomers in the starting materials 3. The 1H NMR and 13C NMR spectra clearly showed the chemical equivalence of the two ortho-palladated fragments, while 19F NMR spectra showed the equivalence of the bridging trifluoroacetate ligands. This means that only the transoid

• Figure 5, provides additional information. Complex 4a has a dinuclear structure in which each Pd atom is surrounded by one C,N-ortho-metallated oxazolone and two oxygen atoms of the trifluoroacetate ligands, which act as bridging ligands between the two Pd(C^N) fragments. In turn, the two Pd(C^N

• those found in related examples reported in the literature and do not show additional noteworthy features [28][29][30]. From the observation of the molecular structure of 4a, it is clear how the geometrical constraints of the ligands in complexes 3 establish unequivocally the stereoselective formation

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

• after reduction of the Ruppert–Prakash reagent with sodium borohydride [39]. The key of success was the use of bulky IPr and SIPr ligands to stabilize the organometallic species. Indeed, in the case of IPr as a ligand, the complex was stable in solution at room temperature for at least 24 hours. The

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

• to give 176 was carried out using Selectfluor as the fluorination reagent. The direct α-C(sp3)–H fluorination of the starting compound 174 was catalyzed by Cu(OAc)2 with (R)-3-hydroxyquinuclidine ligand 175. Comparative studies demonstrated that using ligand 175 rather than other ligands gave higher

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• variety of methods employing the chiral ligands L9–L13 that, in combination with copper, efficiently catalysed the ACA of diethylzinc to 5,6-dihydro-2-pyranone (Scheme 8), providing access to chiral β-substituted lactones with high enantioselectivity and conversion [33][34][35][36][37]. Although the

• acceptors with trialkylaluminium reagents was explored by the group of Alexakis in 2009 (Scheme 11) [41]. Various chiral phosphoramidite ligands, in combination with a copper salt, were found to be efficient catalysts for this transformation, with the best results obtained with the ligand L16. Feringa and

• could also activate the leaving group. After testing several kinds of phosphoramidite ligands with copper salts, the catalyst system L17/CuTc was selected for further studies. The solvent was found to play a crucial role in this reaction, with MTBE as the solvent of choice. Various organoaluminium

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

• enantioselectivities (up to 88% ee) under mild conditions. The chiral-bridged biphenyl monophosphine ligands developed by our group exhibit significant superiority to the naphthyl counterpart MOP in both reactivity and enantioselectivity control. The large steric hindrance from π-conjugated ortho-substituents of the

• from chemists because of their widespread appearance in biologically active compounds [1][2][3][4] such as vancomycin [5] and korupensamine A [6] and as useful chiral ligands in asymmetric catalysis. Different strategies with various metals and phosphine ligands had been successfully employed for the

• efficient synthesis of this scaffold [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], like Hiyama [23][24], Negishi [25][26] or Suzuki–Miyaura couplings [27][28][29][30][31][32][33][34][35][36]. In these synthetic strategies, the reaction system of palladium with chiral phosphine ligands was

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• been shown that derivatives thereof have a great potential to serve as functional units in DNA-binding ligands [54], fluorescent dyes and chemosensors [55][56][57][58][59]. Furthermore, we have already demonstrated that styryl-substituted quinolizinium derivatives exhibit ideal photophysical and DNA

• -binding properties to be used as DNA-sensitive fluorescent probes in cell imaging [60][61][62] or as photoswitchable DNA ligands [63]. Therefore, we were interested in a combination of the photochromic properties of the spirooxazine moiety with the advantageous photophysical and biological properties of

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

• applications in various synthetic fields by utilizing the ability of copper to sustain mono- and bielectronic elementary steps. Further to the development of well-defined copper complexes with classical ligands such as phosphines and N-heterocyclic carbenes, a new and fast-expanding area of research is

• exploring the possibility of a complementing metal-centered reactivity with electronic participation by the coordination sphere. To achieve this electronic flexibility, redox-active ligands can be used to engage in a fruitful “electronic dialogue” with the metal center, and provide additional venues for

• electron transfer. This review aims to present the latest results in the area of copper-based cooperative catalysis with redox-active ligands. Keywords: bioinspired catalysis; biomimetic copper complexes; cooperative catalysis; redox-active ligands; redox catalysis; Introduction Interaction of earth

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• ][4]. A heterocyclic ring containing a P atom appears in many popular P(III)-ligands, such as BPE, DuPhos, TangPhos, DuanPhos, ZhangPhos [5][6][7][8][9][10][11], among which a number of species may be considered as privileged ligands for transition metal-catalyzed enantioselective transformations [12

• ]. Among the P-heterocycles with various ring size, the five-membered derivatives received special attention due to their optimal bond angles and shapes [13][14]. Besides their application as ligands [13][15], the five-membered heterocycles may also be valuable organocatalysts in reactions involving a P

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

• co-workers [39] used a comparatively simple ligand to perform asymmetric silylations of imines. Different ethylenediamine-based ligands (L3–L5) were screened from which L3 proved to give even better yields and ees (Scheme 13). The use of this ligand was explored with other substrates 56 and found to

• use of catalytic Cu(CHB)2/diisopropyl ethylamine in m-xylenes/t-BuOH gave the E-isomer (99% selectivity; Scheme 30, right; conditions B). They also screened various bisoxazoline-containing ligands (for example Scheme 31, L17) for chiral induction which led to good enantioselectivities, in addition to

• excellent E:Z ratios within the resulting alkenes. This methodology could be applied to a wide variety of compounds, including those containing heterocycles (176–178). In a later study [67], they found that by changing ligands, a dramatic switch in the selectivity could be induced in silyl additions to

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• chemical industry by offering a practical synthetic tool for the conversion of aryl iodides to arylaldehydes. Results and Discussion Effects of Rh species Rhodium salts coordinated with proper ligands have been reported to be able to realize the activation of CO and H2 and thus might achieve the reductive

• direct coupling products (namely, benzene and biphenyl) were detected as the main byproducts by GC–MS. This observation also explains why the conversions were always higher than the yields. Effects of ligands Ligands play a decisive role in adjusting the catalytic ability of metal cations [12][13][41][42

• ][43][44][45][46][47][48][49][50][51]. Different ligands coordinating with the same metal cations could make a difference between full conversion with nearly quantitative yields and no reactions. To obtain the optimized conditions, 13 kinds of ligands were tested and their structures are included in

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• suitable ligands [14]. Ligands serve to increase and modulate the reactivity of copper salts. In the first attempt, tris((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)amine (TBTA) considerably speds up the copper-catalyzed cyclization [15]. Many structurally diverse ligands, such as nitrogen-, phosphorus-, carbon

• -, oxygen-, and sulfur-containing ligands were investigated soon after the disclosure of the auxiliary effect of ligands on copper-catalyzed alkyne–azide cycloaddition reactions [16][17]. Heterogeneous catalysts are safer than their homogeneous counterparts. They also offer some advantages, such as the ease

• 1,2-dichloroethane by ultrasonication. After adding N,N-diisopropylethylamine, the mixture was heated at reflux for 20 h. The nanoparticles 107 were magnetically separated and finally, the corresponding complexes of copper(I) and copper(II) with the NHC ligands, 108–111, were prepared as shown in

Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

• Shohei Mimura,
• Sho Mizushima,
• Yohei Shimizu and
• Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

• chiral p-tol-BINAP/copper catalyst established the excellent utility of chiral bisphosphine ligands for this type of reaction [4]. Surprisingly, however, chiral ligands based on N-heterocyclic carbenes (NHCs) [12] have not been applied to the conjugate reduction of α,β-unsaturated carbonyl compounds

• product 2i with comparable results (Table 2, entry 10, 81% yield, 79% ee). Proposed catalytic cycle Based on the experimental observations and previous knowledge of the catalysis of phenol–NHC chiral ligands [14][15][16][17][18], we propose a catalytic cycle as shown in Scheme 1. LiOt-Bu abstracts the two

• enantioselectivity. Conclusion A chiral phenol–NHC ligand efficiently promoted the enantioselective conjugate reduction of α,β-unsaturated esters with a hydrosilane. To the best of our knowledge, this is the first demonstration of the applicability of chiral NHC ligands in Cu-catalyzed enantioselective conjugate

Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons

• Goki Hirata,
• Yu Yamane,
• Naoya Tsubaki,
• Reina Hara and
• Takashi Nishikata

Beilstein J. Org. Chem. 2020, 16, 502–508, doi:10.3762/bjoc.16.45

• with good regio- and stereoselectivity. Results and Discussion In our preliminary research, we tried various Cu salts, including CuI, CuBr, CuCl, CuOAc, and CuOTf, and ligands, including PPh3, 1,10-phenanthroline (1,10-Phen), N,N,N',N'',N''-pentamethyldiethylenetriamine, and tris(2-pyridylmethyl)amine

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

• important role to promote this ring-opening N-alkylation, but also acts as an oxygen donor. Keywords: N-alkylation; oxazolines; potassium tert-butoxide; ring opening; thiazolidinones; Introduction 2-Oxazolines are important structural units in pharmaceutical applications and efficient ligands in

Aerobic synthesis of N-sulfonylamidines mediated by N-heterocyclic carbene copper(I) catalysts

• Faïma Lazreg,
• Marie Vasseur,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2020, 16, 482–491, doi:10.3762/bjoc.16.43

• , the presence of an N-atom in the amidine structure leads to opportunities as ligands and organocatalysts [6][7][8]. N-Sulfonylamidines and N-sulfonylimidates are members of a specific class of these amidines. One initial methodology developed for the formation of sulfonylamidines was based on the

• , NHCs (NHC = N-heterocyclic carbene) have become ligands of choice to permit the stabilisation and formation of highly reactive transition metal species [14]. Thus, significant advances have been achieved using this supporting ligand family [15][16][17][18][19]. Recently, our group contributed to this

• pyridine derivative 4, of the heteroleptic normal/mesoionic carbene complex 5, and of the homoleptic mesoionic triazole derivative 6 (Figure 1). This special class of ligands presents unique electronic and steric properties and lead to unusual reactivity [23][24][25][26][27][28]. [Cu(IPr)(Pyr)]OTf (4) was

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• bisnitrogen ligands, and particularly phenanthroline derivatives, were used in the pioneering reports from McMillin [14] and Sauvage [15]. For decades, their use in organic synthesis, and particularly catalysis, has been ignored. However, since 2012, a renewed interest toward their use in catalysis has been

• lactone synthesis using a copper-photocatalyzed PCET reaction. Photocatalytic Pinacol coupling reaction catalyzed by [Cu(I)(pypzs)(BINAP)]BF4. The ligands of the copper complex are omitted for clarity. Azide photosensitization using a Cu-based photocatalyst. Funding This work was partially supported by

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

• been demonstrated. Keywords: borane; cyclic compound; organosilane; sila-Friedel–Crafts; silylation; Introduction Six-membered silacyclic compounds, such as phenoxasilin and phenothiasilin derivatives, are attractive compounds for applications as organic electronic materials [1][2][3][4], ligands [5

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

• , Pietermaritzburg 3201, South Africa 10.3762/bjoc.16.35 Abstract Diverse P,N-phosphine ligands reported to date have performed exceptionally well as auxiliary ligands in organometallic catalysis. Phosphines bearing 2-pyridyl moieties prominently feature in literature as compared to phosphines with five-membered N

• -heterocycles. This discussion seeks to paint a broad picture and consolidate different synthetic protocols and techniques for N-heterocyclic phosphine motifs. The introduction provides an account of P,N-phosphine ligands, and their structural and coordination benefits from combining heteroatoms with different

• basicity in one ligand. The body discusses the synthetic protocols which focus on P–C, P–N-bond formation, substrate and nucleophile types and different N-heterocycle construction strategies. Selected references are given in relation to the applications of the ligands. Keywords: ligand synthesis; P,N

Synthesis and herbicidal activities of aryloxyacetic acid derivatives as HPPD inhibitors

• Man-Man Wang,
• Hao Huang,
• Lei Shu,
• Jian-Min Liu,
• Jian-Qiu Zhang,
• Yi-Le Yan and
• Da-Yong Zhang

Beilstein J. Org. Chem. 2020, 16, 233–247, doi:10.3762/bjoc.16.25

• process, all water molecules were removed. The ligand and protein were prepared with the Dock Ligands tool before docking. By using Define and Edit Binding Site tool to identify the active site. Then the center of the native ligand was deleted. Utilizing the CDOCKER, the prepared ligand was docked into

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• reagents was reported by Alexakis and co-workers in 2010 [14]. After screening various chiral phosphine-based ligands, the combinations of either phosphoramidite L1 with Cu(OTf)2, or (R)-BINAP (L2) with copper thiophenecarboxylate (CuTC) appeared to be the most efficient for the addition of Et2Zn to a

• enantioselective catalysis was reported by Evans and co-workers in 2005 [34]. The selected asymmetric transformation was the Friedel–Crafts 1,4-addition involving indole derivatives as nucleophiles, catalyzed by a scandium(III) triflate complex with chiral bis(oxazolinyl)pyridine ligands. As highlighted by Evans

• , Mauduit, Campagne, and co-workers set up a highly enantioselective 1,4-addition of dimethylzinc to a wide scope of α,β-unsaturated acylimidazoles 35 [38]. Among the various ligands screened in combination with copper(II) triflate, the hydroxyalkyl-chelating NHC precursor L14 proved to be the most

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• ) have been reported to have antimicrobial [1], antifungal (e.g., tolnaftate and tolciclate) [2], antimycobacterial [3], human leucocyte elastase inhibitory [4], TRPV1 antagonistic [5], and PPARα1γ dual antagonistic [6] properties, and also act as intermediates in the syntheses of HIV-1 integrase ligands

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• alkenylation of indole with n-butylacrylate in the presence of thioether ligands [32]. In the context of C–H activation reactions, the catalyst of choice has mostly been Pd [33][34]. However, as part of the search for newer and more cost-efficient catalysts, other transition metals, such as Ru, have also been

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• -33501 Bielefeld, Germany Department of Chemistry, Structural Chemistry Facility, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada 10.3762/bjoc.16.13 Abstract It was demonstrated that styrylquinolizinium derivatives may be applied as photoswitchable DNA ligands. At

• the intercalating monomers upon irradiation at 315 nm in the presence of DNA. As a result, it is possible to switch between these two ligands and likewise between two different binding modes by irradiation with different excitation wavelengths. Keywords: azoniahetarenes; DNA ligands

• ][6][7][8][9][10]. Nevertheless, most DNA-binding ligands have an insufficient selectivity towards the targeted nucleic acid, and they also accumulate in healthy tissue, so that the chemotherapeutic treatment of tumors with DNA-binding drugs still suffers from severe side effects because of the