Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• catalysis is mainly [Ru(bpy)3]2+ [21], due to its strong MLCT (metal-to-ligand charge transfer) absorption, the excellent yield of its triplet state and the long lifetime, the versatile redox behavior (Ru3+ vs Ru+) in quenching processes and the chemical and photochemical robustness. Despite their positive

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• -catalyzed lactonization, and iii) construction of the epoxides by a newly developed methodology. The synthesis commenced from the alkylation of tetralone 22 with 3-(2-iodoethyl)dihydrofuran-2(3H)-one (23) to give diastereomeric lactones that subsequently reacted with dimethylamine to afford a 1:1 mixture of

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• [KA'] fragment (entry 6). In structurally characterized polymeric [LnKA']∞ complexes, the average K–C(allyl) distances span a comparatively narrow range, regardless of coordinated ligands and the change in formal coordination number of the K+ cation: i.e., 3.01 Å in [KA']∞, 3.03 Å in [KA'(thf)3/2

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• %, 6: 30%; d) (3-(2-methoxyethoxy)prop-1-yn-1-yl)magnesium bromide, THF, 60 °C, 85%; e) carbon monoxide, sodium formiate, [Pd(PPh3)2Cl2], anhydrous DMF, 100 °C, 8: 19%, 9: 35%; f) cyanoacetic acid, piperidine, MeCN, CHCl3, 80 °C, BOD-TTPA: 34%, BOD-TTPA-alk: 26%. a) Absorption spectra of compounds BOD

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

• , the rate-limiting step of the reaction takes place through a highly asynchronous (3 + 2) concerted cycloaddition through a single transition structure (one kinetic step). The ELF analysis identifies the reaction as a typical one-step-two-stages process and corroborates the existence of a transient

• Waegell et al. proposed a new (3 + 2) asynchronous concerted mechanism [19][20], both groups converged to the latter proposed mechanism when Bakke et al. changed the interpretation of their kinetic isotopic experiments [21][22][23][24]. The (3 + 2) concerted mechanism was further confirmed by DFT

• mechanism consisting of a (3 + 2) transition state has been confirmed as the preferred one [25], we restricted the study to this approach. Computational Methods The procedures are analogous to those previously reported [43]. All of the calculations were performed using the Gaussian 09 program [47

Synthesis of pyrrolo[1,2-a]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts

• Anthony Choi,
• Rebecca M. Morley and
• Iain Coldham

Beilstein J. Org. Chem. 2019, 15, 1480–1484, doi:10.3762/bjoc.15.149

• with triethylamine promoted the reaction of the resulting quinolinium ylides (formally azomethine ylides) with electron-poor alkenes by conjugate addition followed by cyclization or by [3 + 2] dipolar cycloaddition. The pyrroloquinoline products were formed as single regio- and stereoisomers. These

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• Information File 1, Figure S21) to satisfy maximum site occupancy. Upon the addition of 2 equiv of rhodium porphyrin 3 [37], DABCO was selectively removed from complex 12 [38] affording the sandwich complex 7 = [(3)2(4)] leaving complex 11 untouched and liberating two equiv of 10 (incomplete self-sorting

• , 3, and 4 and of the resulting products, i.e., rectangle 5, sandwich 6 and rhodium porphyrin dimer 7. Comparison of partial 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of (a) ligand 2; (b) ligand 1; (c) porphyrin 3; (d) complex 7 = [(3)2(4)]; (e) rectangle 5 = [Cu4(1)2(2)2]4+]; (f) sandwich complex 6

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• mixture of 19 and 18 (3:2 ratio), accompanied with a small amount of 22. As a substitute for dianthracene 19, thermally more stable substrate, anthracene-N-methyl maleimide adduct 25 [54] was prepared by Diels–Alder reaction under high pressure conditions as well as by microwave-assisted reaction and

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

• Herman O. Sintim,
• Hamad H. Al Mamari,
• Hasanain A. A. Almohseni,
• Younes Fegheh-Hassanpour and
• David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

• area have recently culminated in two communicated syntheses of 6,7-dideoxysqualestatin H5 (DDSQ (2), Figure 1) [12][13]. The centrepiece of both of these strategies is a rhodium(II)-catalysed tandem carbon ylide formation from a diazoketone 3 (Scheme 1) and stereoselective [3 + 2] cycloaddition with a

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

• diastereoselective [3 + 2] cycloaddition reaction [14][15]. The ring expansion sequence 1 → 2 → 6 → 8 has been used as a key step in the synthesis of (±)-fragranol [16], (±)-grandisol [16], (±)-α-cuparenone [17] and (±)-herbertene [17]. Aryl cycloropyl sulfides 1 are most frequently prepared by cyclopropylation of

Design of a double-decker coordination cage revisited to make new cages and exemplify ligand isomerism

• Sagarika Samantray,
• Sreenivasulu Bandi and
• Dillip K. Chand

Beilstein J. Org. Chem. 2019, 15, 1129–1140, doi:10.3762/bjoc.15.109

• -diylbis(methylene) dinicotinate (L1) is the focus of this work. Complexation of cis-Pd(tmeda)(NO3)2 with L1 at a 1:1 or 3:2 ratio produced [Pd(tmeda)(L1)](NO3)2 (1a). The reaction mixture obtained at 3:2 ratio upon prolonged heating, produced a small amount of [Pd3(tmeda)3(L1)2](NO3)6 (2a). Complexation

• with the ligand L1 at two different metal-to-ligand ratios (1:1 and 3:2). We also carried out the complexation of bare palladium(II) with the ligand L1 at two different metal-to-ligand ratios (1:2 and 3:4). The complexation reactions performed in DMSO-d6 allowed the monitoring of complex formation and

• Supporting Information File 1. Complexation of cis-protected palladium(II) with ligand L1 at a 3:2 metal-to-ligand ratio The addition of three equivalents of cis-Pd(tmeda)(NO3)2 to a clear solution of two equivalents of ligand L1 in DMSO-d6 produced a turbid mixture. However, a clear yellow solution was

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

• Yang Liu Julie Oble Giovanni Poli Sorbonne Université, Faculté des Sciences et Ingénierie, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, 4 place Jussieu, 75005 Paris, France 10.3762/bjoc.15.107 Abstract Two complementary [3 + 2] annulation protocols between 3-oxoglutarates and cyclic γ-oxy

• -2-cycloalkenones, simply differing on the reaction temperature, are disclosed. These domino transformations allow C–C/O–C or C–C/C–C [3 + 2] annulations at will, via an intermolecular Pd-catalyzed C-allylation/intramolecular O- or C-1,4-addition sequence, respectively. In particular, exploiting the

• success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. This [3 + 2] C–C/O–C bond forming annulation protocol could be also extended to 1,3,5-triketones as well as 1,3-bis-sulfonylpropan-2

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• economy is quite low, since a half of the diaryliodonium salt 87 is lost in the process. Replacing the arene substrate 86 by ketones, and keeping nearly equal reaction conditions, the same authors have achieved an efficient synthesis of 3-(2-oxopropyl)- or pentacyclic isoindolinones 90 or 92 (Scheme 26

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

• Victoria V. Lipson,
• Tetiana L. Pavlovska,
• Nataliya V. Svetlichnaya,
• Anna A. Poryvai,
• Nikolay Yu. Gorobets,
• Erik V. Van der Eycken,
• Irina S. Konovalova,
• Svetlana V. Shiskina,
• Alexander V. Borisov,
• Vladimir I. Musatov and
• Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

• selectively led to the corresponding Knoevenagel–Michael adducts containing a free amino group in the imidazole fragment. The adducts derived from Meldrum’s acid have been smoothly converted into 1,7-diaryl-3-amino-6,7-dihydro-5H-pyrrolo[1,2-c]imidazol-5-ones and 3-(2-amino-4-aryl-1H-imidazol-5-yl)-3

• (38), 104 (29), 77 (100), 44 (41), 43 (19); anal. calcd for C18H15N3O (289.12) C, 74.74; H, 5.19; N, 14.53; found: C, 72.28; H, 6.79; N, 13.11. General procedure for the synthesis of 3-(2-amino-4-aryl-1H-imidazol-5-yl)-3-arylpropanoic acids: A mixture of the corresponding adduct 4 (0.1 mmol) and 0.08

• structure of 1-([1,1'-biphenyl]-4-yl)-5-oxo-7-phenyl-6,7-dihydro-5H-pyrrolo[1,2-c]imidazol-3-aminium 2,2,2-trifluoroacetate 9i according to X-ray diffraction data. Thermal ellipsoids of atoms are shown at 50% probability level. Molecular structure of 3-(2-amino-4-phenyl-1H-imidazol-5-yl)-3-(p-tolyl

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• most organic compounds. The O 1s spectrum of the monolayers consist of two components at 531.5 eV and 533.2 eV (SAM 3) and 531.6 eV and 533.3 eV (SAM 7) for oxygen atoms involved in the O=C and O−C bonds, respectively [55]. The slight deviation from the peak area ratio of 3:2 for I(531.5 eV)/I(533.5 eV

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• through self-sorting led to three structurally different metallosupramolecular Fe(II) complexes. Under mechano-milling conditions the tetranuclear [Fe4(AD2)6]4− 22-component cage 26, dinuclear [Fe2(BD2)3]2− 11-component self-assembled helicate 27 and 5-component mononuclear [Fe(CD3)]2+ complex 28 could be

• ester cages of type 22 [64]. Mechanochemical synthesis of borasiloxane-based macrocycles. Mechanochemical synthesis of 2-dimensional aromatic polyamides. Nitschke’s tetrahedral Fe(II) cage 25. Mechanochemical one-pot synthesis of the 22-component [Fe4(AD2)6]4− 26, 11-component [Fe2(BD2)3]2− 27 and 5

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• colorless solid. Anomers could be separated by column chromatography and were obtained as isomeric mixtures (indicated as a and b). Rf = 0.38 (petroleum ether/ethyl acetate 3:2); α-isomer: 1H NMR (400 MHz, CDCl3) δ 6.14–6.02 (m, 1H, H-1), 5.29 (dd, J = 10.3, 4.3 Hz, 1H, H-3), 5.19 (‘t‘, J = 10.1 Hz, 1H, H-4

• over 20 min) and obtained as mixture of isomers. Retention time β-anomer: 12.6 min, α-anomer: 13.4 min. Rf = 0.30 (petroleum ether/ethyl acetate 3:2); α-isomer: 1H NMR (400 MHz, CDCl3) δ 6.19 (d, J = 3.7 Hz, 1H, H-1), 5.36–5.12 (m, 2H, H-3, H-4), 4.77 (d, J = 9.5 Hz, 1H, NH), 4.26 (dd, J = 12.5, 4.1 Hz

Intramolecular cascade annulation triggered by rhodium(III)-catalyzed sequential C(sp²)–H activation and C(sp³)–H amination

• Liangliang Song,
• Guilong Tian,
• Johan Van der Eycken and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 571–576, doi:10.3762/bjoc.15.52

• molecules for further studies. Selected examples of natural products with a tricyclic indolizinone scaffold. Previous work and this approach. Reaction scope. Reaction conditions: 1 (0.3 mmol), [RhCp*Cl2]2 (0.015 mmol), CsOAc (0.6 mmol), 1,4-dioxane (3.0 mL), the ratio of isolated 3:2 was shown in

Dirhodium(II)-catalyzed [3 + 2] cycloaddition of N-arylaminocyclopropane with alkyne derivatives

• Wentong Liu,
• Yi Kuang,
• Zhifan Wang,
• Jin Zhu and
• Yuanhua Wang

Beilstein J. Org. Chem. 2019, 15, 542–550, doi:10.3762/bjoc.15.48

• Abstract Dirhodium(II) complex-catalyzed [3 + 2] reactions between N-arylaminocyclopropanes and alkyne derivatives are described. The cycloaddition products proved to be versatile synthetic intermediates. trans-Cyclic β-amino acids and derivatives thereof can be conveniently synthesized using this

• cycloaddition protocol. Keywords: [3 + 2]; alkyne; cycloaddition; cyclopropanes; dirhodium catalysis; N-arylaminocyclopropanes; Introduction N-Arylaminocyclopropanes 1 are important structural motifs for pharmaceuticals and are found especially in marketed fluoroquinolone antibiotics [1], such as

• cycloaddition chemistry based on compound 1. Zheng et al. [7] first reported on the [3 + 2] cycloaddition reaction of 1 with an alkene or alkyne mediated by visible light by the aid of the photocatalyst [Ru(bpz)3](PF6)2. Our group reported the metal catalyst itself, particularly the dinuclear rhodium complex

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• . Similarly, compounds 2–7 were synthesized using different amines including 2-phenylethylamine (for 2), 1-methyltryptamine (for 3), 2-(2-naphthyl)ethylamine hydrochloride (for 4), 2-(1-naphthyl)ethylamine hydrochloride (for 5), 2-(1H-inden-3-yl)ethylamine hydrobromide (for 6) [21], and 2-(1-benzofuran-3-yl

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• reactivity analogous to aldonitrones, which enables their conversion via [3 + 2]-cycloadditions with dipolarophiles such as activated ethylenes [8][9], activated acetylenes [10][11] or isocyanates [11][12]. The initially formed [3 + 2]-cycloadducts undergo spontaneous secondary conversions leading to re

• were achieved with 7a and 7c,d. A plausible explanation of the sulfur-transfer mechanism via the intermediate [3 + 2]-cycloadduct A is presented in Scheme 5. The eliminated monothione 11b enters an analogous reaction with the starting imidazole N-oxide 7, leading to a second molecule of 10 and 2,2,4,4

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• undergo Ru-promoted RCM and CM when the G-III catalyst is used under heterogeneous conditions (water/tert-butanol 3:2) with a large excess of Mg2+. Also in this case, the role of Mg2+ is to protect the oligonucleotide from Ru-induced decomposition by binding to the phosphate backbone. Table 12 summarizes

Convergent synthesis of the pentasaccharide repeating unit of the biofilms produced by Klebsiella pneumoniae

• Arin Gucchait,
• Angana Ghosh and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2019, 15, 431–436, doi:10.3762/bjoc.15.37

•  1). Initially it was planned to couple the disaccharide acceptor 13 with the trisaccharide thioglycoside donor 19 using a [3 + 2] convergent glycosylation strategy to achieve the pentasaccharide derivative 20. However, the desired product was obtained in poor yield, which did not allow upscaling of

• ][23] exclusively furnished 2-azidoethyl (2-O-acetyl-3,4,6-tri-O-benzyl-1-thio-α-D-mannopyranosyl)-(1→3)-2-O-benzyl-4,6-O-benzylidene-β-D-glucopyranoside (12) in 80% yield, which on treatment with sodium methoxide [24] led to the formation of disaccharide acceptor 13 in 98% yield (Scheme 1). In another

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• 28% yield and was contaminated with Nam. The removal of acetyl groups from 4a gave NR+Cl− in 38% yield as a mixture of β- and α-anomers, with β/α ratio being equal to 3:2. The work of Migaud et al. [28] describes novel vitamin B3 conjugates, which were generated by glycosylation of nicotinate

• anhydrous methanol at 0–5 °C for 14 h to afford a 3:2 mixture of β- and α-anomers of NMN (as determined by 1H NMR) in good to moderate yields (24–60% based on 5-phosphoribose 27) depending on the reaction scale, with lower yield being achieved at the larger scale due to difficulties in removing ammonia. β

• means of purification on a Dowex formate column and characterized by 1H NMR spectroscopy. The low isolated yield of the final β-NAD+ bisphosphonate derivative (13%) may be explained by the fact that isopro-NR+ used was a mixture of β/α anomers with respective ratio of 3:2 and that the coupling

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• another molecule Mn(OAc)3 [48]. Later, Shi et al. demonstrated an oxidative annulation of MCPs 1 with 1,3-dicarbonyl compounds 7 using manganese(III) catalysis under room temperature conditions, which afforded 4,5-dihydrofuran derivatives 8 as [3 + 2] annulation products (cyclopropyl retained adducts) in

• moderate to good yields [49]. This transformation also gave another six-membered cyclic compounds 9 (cyclopropyl opened adducts) via ring-opening and cyclization process (Scheme 3). However, the [3 + 2] annulation reaction did not occur under the standard conditions when the MCPs 1 was without an aromatic

• group. The first method for direct [3 + 2] radical cycloaddition of MCPs 1 with elemental chalcogens 10 (S, Se, Te) was developed by Yu and co-workers. This strategy presented a simple and efficient method for the synthesis of methylene-1,2-dichalcogenolanes 11 (Scheme 4) [50]. This reaction proceeded