Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• (NDA) and naphthalenemonoimide (NMI) moieties. The double C–H bond activation initially used palladium(II) acetate in acetic acid as the coupling system. The subsequent screening revealed, however, that a catalytic coupling could be also achieved in the presence of silver(I) carbonate as the

• -dipyrrolylpropanes (NDA3H, NMI3H) were reacted with palladium(II) acetate in acetic acid to furnish the expected bipyrrole dilactams in 43–53% yields (Table 1, entries 1, 6, 11 and 17). Remarkably, it was found that cNMI2O and cNMI3O were obtained along with the intermediate α-unsubstituted boomerangs, cNMI2H and

• that the coupling and α-oxygenation can also be achieved with 1 equiv of Pd(OAc)2 in the presence of 2 equiv of silver carbonate. Nevertheless, Ag2CO3 oxidation provided lower yields and the efficiency of this variant was dramatically diminished when the loading of palladium(II) acetate was decreased

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• above results strongly suggested the existence of an equilibrium between the intermediates corresponding to products 5b and 5c. A possible mechanism is shown in Scheme 2 [21][22][23][24][25]. After the oxidative addition of 4b to Pd0 to generate intermediate A, the neutral palladium(II) intermediate B

Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

• Zeguo Fang,
• Nawaf Al-Maharik,
• Peer Kirsch,
• Matthias Bremer,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

• developed by Bosch [16]. Accordingly, treatment of 16a with butyl vinyl ether, bathophenanthroline (BPhen) and Et3N, using palladium(II) trifluoroacetate as a catalyst, gave vinyl ether 17 in 62% yield in a single step. Finally, difluorocarbene-mediated difluorocyclopropanation generated 10 in 50% yield

Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

• Jan Geldsetzer and
• Markus Kalesse

Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64

• double bonds into the corresponding (Z)-monohalogenated derivatives using palladium(II) acetate, triphenylphosphine and tributyltin hydride. Following this procedure, we were able to obtain (Z)-bromide 4 in four steps and an overall yield of 39% [21][22][23][24]. Cross coupling of fragments 3 and 4 The

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

• multitask nanocatalyst was used for one-pot Sonogashira-“click”/“click”-Heck sequences [87]. Palladium(II) acetate, copper(II) acetate, and charcoal were dispersed in methanol. In order to remove oxygen from the reaction mixture, hydrogen gas was passed through the medium. Then, the solution was stirred at

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

• 57. Coupling of 57 with Ph2PCl·BH3 resulted in the boron-protected ligand 58, which was deprotected with Et3N. Alternatively, 1,1’-bis(diphenylphosphino)ferrocene (dppf) with palladium(II) acetate was used to catalyze the reduction of 55 generating the pyridine scaffold 57. Subsequent lithiation and

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• compounds 1 and 2, was successfully achieved. We used tri(o-tolyl)phosphine (P(o-tol)3, palladium(II) acetate (Pd(OAc)2) and obtained the desired product (E)-benzyl 3-(6-aminopyridin-3-yl)acrylate in 86% yield (see Supporting Informaiton File 1). However, when the same conditions were applied to alkyl 3-(6

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• substituent in an attempt to enhance water solubility. Late-stage functionalization of the ortho-position was carried out through a palladium(II)-catalyzed C–H activation, resulting in ortho-brominated azobenzenes [21]. Photochemical characterization Despite the morpholino substituent, compound 4 was found to

Iodine-mediated hydration of alkynes on keto-functionalized scaffolds: mechanistic insight and the regiospecific hydration of internal alkynes

• Zachary Lee,
• Brandon R. Jones,
• Nyochembeng Nkengbeza,
• Michael Phillips,
• Kayla Valentine,
• Alexis Stewart,
• Brandon Sellers,
• Nicholas Shuber and
• Karelle S. Aiken

Beilstein J. Org. Chem. 2019, 15, 2747–2752, doi:10.3762/bjoc.15.265

• extremely harmful to environmental and biological systems [3]. In light of mercury’s toxicity, the synthetic community has given much attention to the use of less harmful reagents. Success has been obtained with many other transition metal salts, for example, palladium(II) [4][5], rhodium(III) [6], copper

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

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• sidewalls have been synthesized and characterized. The macrocycle containing isophthalamide bridges can bind square-planar chloride coordination complexes of gold(III), platinum(II), and palladium(II) in CDCl3, while the macrocycle with 2,6-pyridine dicarboxamide bridging units cannot. This may be due to

• a pair of new tetralactam macrocycles with 2,3-dibutoxynaphthalene as the sidewalls. The tetralactam macrocycle with 2,6-pyridine dicarboxamide cannot bind square-planar chloride coordination complexes of gold(III), platinum(II), and palladium(II) in CDCl3, while the macrocycle containing

• isophthalamide bridging units bind these complexes with decent binding affinities. This macrocycle shows similar binding affinity to chloride, weaker affinity to the chloride complex of gold(III), and much stronger affinities to the chloride complexes of platinum(II) and palladium(II), when compared to the

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

• Sagarika Samantray Sreenivasulu Bandi Dillip K. Chand Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India 10.3762/bjoc.15.109 Abstract The complexation study of cis-protected and bare palladium(II) components with a new tridentate ligand, i.e., pyridine-3,5

• coordination bonds enable the construction of designer targeted molecules with ease. The use of a palladium(II) component for complexation with a non-chelating bi- or polydentate ligand (usually N-donor ligands) is particularly advantageous for the construction of a variety of metallocages [1][2][3][4][5

• ]. Complexation of cis-protected palladium(II), i.e., (PdL’) or bare palladium(II) with non-chelating bidentate ligands is known to afford a series of (PdL’)mLm or PdmL2m-type self-assembled coordination complexes [5]. Pd2L4-type cages are the simplest representatives among the PdmL2m-type complexes, yet most

Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

• infrared spectroscopy, samples were pelleted with potassium bromide and analyzed on a Shimadzu FTIR-84005. 1,2-Dideoxy-1-(4-phenyl-1H-1,2,3-triazol-1-yl)-β-D-galactoheptulose (1a): Compound 10a (42 mg, 0.062 mmol) was dissolved in cyclohexene/ethanol 2:1 (1.5 mL), palladium(II) hydroxide on charcoal (17 mg

• HPLC, UV–vis detection: 98.4%. 1,2-Dideoxy-1-[4-(4-fluorophenyl)-1H-1,2,3-triazol-1-yl]-β-D-galactoheptulose (1b): Compound 10b (50 mg, 0.147 mmol) was dissolved in cyclohexene/ethanol 2:1 (3 mL), palladium(II) hydroxide on charcoal (40 mg, 20 wt %) was added, and the mixture refluxed overnight at 80

• ; purity by HPLC, UV–vis detection: 95.6%. 1,2-Dideoxy-1-[4-(3-fluorophenyl)-1H-1,2,3-triazol-1-yl]-β-D-galactoheptulose (1c): Compound 10c (71 mg, 0.102 mmol) was dissolved in cyclohexene/ethanol 2:1 (4.5 mL), 27 mg of 20 wt % palladium(II) hydroxide on charcoal was added, and the mixture refluxed

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

• Pierre-Antoine Nocquet,
• Aurélie Macé,
• Frédéric Legros,
• Jacques Lebreton,
• Gilles Dujardin,
• Sylvain Collet,
• Arnaud Martel,
• Bertrand Carboni and
• François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

• strategy based on an Evans’ aldol reaction. Mildly oxidizing conditions using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) were used for the removal of the p-methoxybenzyl (PMB) group to provide alcohols 14 (Scheme 3). Several palladium(II) catalysts have been tested for the conversion of alcohols to

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• investigation of the mechanism of the reaction revealed that a Pd(II) to Pd(IV) route is the more likely pathway which was further supported by computational studies. Keywords: cationic palladium(II) complexes; Pd(II)/Pd(IV) complexes; SNS pincer complexes; Suzuki–Miyaura; Introduction The Suzuki–Miyaura C–C

• catalyst for subsequent reactions after simple phase separation [31]. However, the commonly employed phosphorous and carbene ligand-based palladium(II) complexes are found to be in most cases sensitive to moisture and air limiting the scope of their catalytic application in aqueous reactions [32][33]. This

• limitation encouraged for the development of organosulfur ligand based palladium(II) complexes by exploiting the strong donor properties of sulfur. Such complexes are found to be resistant to moisture, air and thermal stress/elevated temperatures and have been applied in catalysing Suzuki–Miyaura coupling

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• enantioselectivity (98% ee) albeit with moderate yield (51%). However, no reaction occurred with ortho-substituted substrates. This process constituted the first example of a palladium(II)-catalyzed addition of arylborons to exocyclic ketimines. Conclusion This review demonstrates that much progress has been

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• is subsequently desilylated with TBAF in the presence of CuCl and DABCO to obtain the alkynylcopper species D. In the meantime oxidative addition of the previously released iodoarene 2 to the Pd(0) species occurs and the resulting palladium(II) complex E then undergoes transmetallation with the

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• ; found, 434.0006. 4'-Methoxy-N-((trifluoromethyl)sulfonyl)-[1,1'-biphenyl]-4-carboxamide (15): Palladium(II) acetate (6 mg, 27 μmol), triphenylphosphine (20 mg, 76 μmol) and H2O (0.5 μL, 28 μmol) were mixed in degassed dimethylacetamide (1.0 mL). The catalyst was preformed by heating the mixture in a

Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-b]quinolines (quindolines)

• Michał Nowacki and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2018, 14, 194–202, doi:10.3762/bjoc.14.14

• (e) [15] and palladium(II) acetate-mediated oxidative cyclization of 3-(phenylamino)quinoline (f) afford quindoline [16]. Some of these syntheses require harsh conditions and multistep procedures. Another drawback of some of the known methodologies is the use of transition metal catalysts for the

Development of a fluorogenic small substrate for dipeptidyl peptidase-4

• Futa Ogawa,
• Masanori Takeda,
• Kanae Miyanaga,
• Keita Tani,
• Ryuji Yamazawa,
• Kiyoshi Ito,
• Atsushi Tarui,
• Kazuyuki Sato and
• Masaaki Omote

Beilstein J. Org. Chem. 2017, 13, 2690–2697, doi:10.3762/bjoc.13.267

• reactions were performed in microwave tubes with clip lids using a Biotage Initiator microwave reactor. Typical procedure for the Hiyama cross-coupling reaction Analogous as described in [24]. In a glovebox purged with argon gas, iodo aniline (1.0 mmol), (2-methylallyl)palladium(II) (0.1 mmol), CuF2 (2.0

Brønsted acid-mediated cyclization–dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines

• Ramana Sreenivasa Rao and
• Chinnasamy Ramaraj Ramanathan

Beilstein J. Org. Chem. 2017, 13, 428–440, doi:10.3762/bjoc.13.46

• reaction mixture was purified through silica gel column chromatography using ethyl acetate/hexane, 30:70 as eluent to afford 12a and 12b in the ratio 79:21. The regioisomers of bromopyrazinone (12a and 12b) (1.0 mmol), bis(triphenylphosphine)palladium(II) chloride (10 mol %, 7 mg) in dimethylformamide (2

Decarboxylative and dehydrative coupling of dienoic acids and pentadienyl alcohols to form 1,3,6,8-tetraenes

• Ghina’a I. Abu Deiab,
• Mohammed H. Al-Huniti,
• I. F. Dempsey Hyatt,
• Emma E. Nagy,
• Kristen E. Gettys,
• Sommayah S. Sayed,
• Christine M. Joliat,
• Paige E. Daniel,
• Rupa M. Vummalaneni,
• Andrew T. Morehead Jr,
• Andrew L. Sargent and
• Mitchell P. Croatt

Beilstein J. Org. Chem. 2017, 13, 384–392, doi:10.3762/bjoc.13.41

•  1, entries 15–18 and Supporting Information File 1 for kinetic information). Although not as efficient, it was found that a palladium(II) catalyst functioned in this reaction, presumably functioning as a pre-catalyst and being reduced in situ to the palladium(0) catalyst (Table 1, entries 19 and 20

Self-optimisation and model-based design of experiments for developing a C–H activation flow process

• Alexander Echtermeyer,
• Yehia Amar,
• Jacek Zakrzewski and
• Alexei Lapkin

Beilstein J. Org. Chem. 2017, 13, 150–163, doi:10.3762/bjoc.13.18

• execution are provided in Supporting Information File 1. Materials Toluene (Sigma-Aldrich, anhydrous, 99.8%), acetic acid (Sigma-Aldrich, ReagentPlus, ≥99.0%), acetic anhydride (Sigma-Aldrich, ReagentPlus, ≥99.0%), 1,1,2,2-tetrachloroethane (Sigma-Aldrich, reagent grade, ≥98.0%), palladium(II) acetate

Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

• Michal Medvecký,
• Igor Linder,
• Luise Schefzig,
• Hans-Ulrich Reissig and
• Reinhold Zimmer

Beilstein J. Org. Chem. 2016, 12, 2898–2905, doi:10.3762/bjoc.12.289

• -oxazine syn-11 in 41% yield. Next, we briefly studied 5-iodo-1,2-oxazine syn-4a as substrate in Heck reactions. The substrate was reacted with the alkyl acrylates 12a (R1 = Me) and 12b (R1 = t-Bu) under phosphine-free conditions [33][34] using 6 mol % of palladium(II) acetate, triethylamine as base and

• ]. When the coupling was performed using palladium(II) acetate, solid NaHCO3 and tetra-n-butylammonium bromide (TBAB) at 130 °C [37][38][42] the desired β-1,2-oxazinyl-substituted dehydroamino acid derivative syn-17 was obtained in 69% yield. We did not prove the Z-configuration of the external C=C bond

Facile synthesis of indolo[3,2-a]carbazoles via Pd-catalyzed twofold oxidative cyclization

• Chao Yang,
• Kai Lin,
• Lan Huang,
• Wei-dong Pan and
• Sheng Liu

Beilstein J. Org. Chem. 2016, 12, 2490–2494, doi:10.3762/bjoc.12.243

• twofold oxidative cyclization. Findings The oxidative biaryl coupling reaction was originally described over 30 years ago using stoichiometric palladium(II) [9][10]. Quite recently, the reaction has been developed to proceed catalytically and widely applied as an atom economic approach to carbazoles [11