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

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

• Antonella Petri,
• Valeria Colonna and
• Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

• stirred at 35 °C and 550 rpm in an open vessel for 24 hours. The reaction was monitored by HPLC analysis and by TLC. At the end of the reaction, the enzyme was filtered under vacuum and washed with triethanolamine buffer (100 mM, pH 7.5, 3 × 2 mL). The recovered enzyme was suspended in buffer and stored

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• not all of the substrate 2 gets dissolved initially. Product 3 is completely soluble at this concentration, so only while the substrate 2 transforms into product 3, 2 gets fully dissolved. Small samples were taken from the reaction flask at regular intervals, diluted and immediately analyzed by ESIMS

A simple and effective preparation of quercetin pentamethyl ether from quercetin

• Jin Tatsuzaki,
• Tomohiko Ohwada,
• Yuko Otani,
• Reiko Inagi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

• position shows the lowest reactivity, while the OH group at 7 position shows the highest reactivity. In the cases of anions 2B, all the corresponding anions 3'-anion 2B, 4'-anion 2B, 5-anion 2B, 7-anion 2B tended to take planar overall structures, that is, the biaryl dihedral angles (3–2–1'–2') were

• energy is shown in parentheses (gas phase) and in brackets (in DMSO, in kcal/mol). The dihedral angle around the biaryl structure (3–2–1'–2') is also shown. Structures of oxyanions derived from quercetin (2) by deprotonation of a single OH group. Top and side views are shown. The relative energy (in blue

• ) is shown (gas phase) and in brackets (in red, in DMSO, in kcal/mol). The positions of the anions are based on the relative energies in DMSO. The dihedral angle around the biaryl structure (3–2–1'–2') is also shown. The natural bond orbital (NBO) charge of the anionic oxygen atom is shown in magenta

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• catalysts given in example in the present review will be presented in Part 3. 2 The different classes of photoredox catalysts (PCs) The main characteristics of the different classes of photoredox catalysts will be given below. If historically, photoredox catalysts were based on metals, but recent

Green synthesis of new chiral 1-(arylamino)imidazo[2,1-a]isoindole-2,5-diones from the corresponding α-amino acid arylhydrazides in aqueous medium

• Nadia Bouzayani,
• Jamil Kraїem,
• Sylvain Marque,
• Yakdhane Kacem,
• Abel Carlin-Sinclair,
• Jérôme Marrot and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2018, 14, 2923–2930, doi:10.3762/bjoc.14.271

• in a trans-orientation with H(4). In addition, various crystallization tests were carried out in order to confirm the absolute stereochemistry by X-ray diffraction. The chiral 3-(2-(methylthio)ethyl)-1-(phenylamino)-1H-imidazo[2,1-a]isoindole-2,5(3H,9bH)dione (5f) crystallized [44][45][46][47][48][49

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow

• Clémentine Minozzi,
• Jean-Christophe Grenier-Petel,
• Shawn Parisien-Collette and
• Shawn K. Collins

Beilstein J. Org. Chem. 2018, 14, 2730–2736, doi:10.3762/bjoc.14.251

• of −1.93 V vs. SCE, much greater than that of Ru(bpy)3+2 (−0.81 V vs SCE), albeit the copper complex has a much shorter excited state lifetime (≈4 ns vs ≈1100 ns for Ru(bpy)3+2). The excited state reduction potential should match favorably with CBr4 (E½ = 0.30 V vs SCE) in DMF [29]. Note that many of

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• % hydrazine in DMF (3 × 2 mL) was added to the resin beads to deprotect N10-(trifluoroacetyl) protecting group by bubbling through resin beads for 10 min each. The resin beads were washed with DMF (3 × 3 mL) followed by isopropanol (3 × 3 mL). The secondary amine group generated in the pteroate core does not

• ; (f) 1% NH2NH2·H2O, DMF (3 × 2 mL) 10 min each; (g) 2 M piperidine in water, rt, 6–12 h; (h) (1) rhodamine B, PyBOP, DIPEA, DMF, 6 h; (2) TFA/TIS/EDT/H2O (9.25:0.25:0.25:0.25, 1 × 5 mL, 30 min; 2 × 5 mL, 5 min); (3) evaporate TFA; (4) precipitate in ice cold diethyl ether. Supporting Information

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation

• Gisela V. Saborit,
• Carlos Cativiela,
• Ana I. Jiménez,
• Josep Bonjoch and
• Ben Bradshaw

Beilstein J. Org. Chem. 2018, 14, 2597–2601, doi:10.3762/bjoc.14.237

• Lycopodium alkaloids carinatine A [11][14][15], 8-deoxyserratinine [10], fawcettidine [10], fawcettimine [7][10], lycojaponicumin C [10], lycopladine A [11][13][14][15], lycoposerramine R [13][14], and sieboldine [19][20] (Figure 2). Results and Discussion Despite the potential of [3 + 2] cycloaddition

• have been used to build the hydrindane bicyclic system, but incorporating a different functionalization pattern in the cyclic compounds. Proposed here is a new methodological approach to functionalized 3a-substituted hydrindane synthesis based on a Danheiser annulation involving a [3 + 2] cycloaddition

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• Keishiro Tahara Ling Pan Toshikazu Ono Yoshio Hisaeda Department of Material Science, Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako 678-1297, Japan Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. China Department of Chemistry

• reaction of H2bpdc, Ru(bpy)2Cl2, and a zinc source under solvothermal conditions (bpy = 2,2′-bipyridine, Scheme 5) [41]. The molecular photosensitizer [Ru(bpy)3]2+ was incorporated into the MOF through adsorption to form Ru@MOF, accompanied by a color change. Furthermore, 1 was effectively immobilized on

• -light-driven through the use of [Ru(bpy)3]2+ as an alternative to reductases. This serves as a simplified analogy for the B12 enzyme-involving system (Figure 2a). The B12-Ru@MOF is the best system for the functional simulation of MMCM among our B12 artificial enzymatic systems. 3. Methyl transfer

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• more recent method starts from an aromatic amine and formaldehyde in the presence of ionic liquids and a controlled amount of 1-methyl-3-(2-(sulfoxy)ethyl)-1H-imidazol-3-ium chloride as the catalyst. The reaction affords the corresponding 1,4-dihydroquinzolin-3-ium tetrafluoroborates, which upon

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• ] demonstrated a synergistic approach involving SM cross coupling and CM to synthesize various substituted trans-stilbene derivatives 89–95 stereoselectively. In this context, 4-vinylphenylboronic acid (86) was subjected to SM coupling using diverse bromoarenes 87a–g in the presence of [Pd(η2-dba){P(o-tolyl)3}2