Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene with alcohols

• Katrina Tait,
• Oday Alrifai,
• Rebecca Boutin,
• Jamie Haner and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 2189–2196, doi:10.3762/bjoc.12.209

• reaction did not proceed and the starting material was recovered. The effect of a palladium(II) catalyst was then investigated (Table 1, entries 4–9), producing variable yields of substituted naphthalene 11a. While attempts using Pd(OAc)2 (Table 1, entry 4) and PdCl2(PPh3)2 (Table 1, entry 5) were

• unsuccessful, palladium(II) catalysts in the absence of a triphenylphosphine ligand were more promising (Table 1, entries 6–9). The palladium(II) catalyst PdCl2(CH3CN)2 generated a high yield of substituted naphthalene 11a after only 24 hours and was chosen to further optimize reaction conditions. When the

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• = Cl, CF3COO, CH3) has been prepared by transmetalation reactions from the corresponding silver complexes and chloro(methyl)(cyclooctadiene)palladium(II). The dimethyl(1-(2-pyrimidyl)-3-(2,6-diisopropylphenyl)imidazolin-2-ylidene)palladium(II) complex was synthesized via the free carbene route. All

• byproduct of the methanol synthesis. Sen reported the activity of palladium(II) catalysts for the oxidation of methane [21] and several groups contributed to the progress in the field which is summarized in recent reviews [22][23]. The system based on N-heterocyclic carbene (NHC) ligands developed in our

• like the bis(1,1'-dimethyl-3,3'-methylenediimidazoline-2,2'-diylidene)palladium(II) dibromide [L2PdBr2] consists of three steps: electrophilic substitution, oxidation and reductive elimination involving a palladium(IV) intermediate [26]. But we also experimentally set out to investigate potential

Flow carbonylation of sterically hindered ortho-substituted iodoarenes

• Carl J. Mallia,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147

• -substituent directly over an axial site (Figure 1). The ortho-substituent therefore acts as a steric buttress hindering the approach of the incoming carbon monoxide thus slowing down the rate of the reaction. An X-ray structure of trans-bromo(o-tolyl)bis(triphenylphosphine)palladium(II) complex was reported

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

• Jakub Saadi,
• Christoph Bentz,
• Kai Redies,
• Dieter Lentz,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

• reaction requires a reduction of palladium(II) back to palladium(0) which is apparently achieved by the present triethylamine. Keywords: 1,2-addition; aryl iodides; ketones; nucleophilic addition; palladium catalysis; Introduction For our systematic studies on samarium diiodide promoted cyclizations

• , palladium(II) has to be reduced back to a palladium(0) species in order to allow a catalytic use of the metal. It is well known that several reagents (alkenes or alcohols [19]) are able to achieve this reduction. We therefore assume that triethylamine is the reducing reagent under the conditions employed in

• -iodoaniline derivative to a tricyclic tertiary alcohol as reported by Solé et al. [23]. Proposed transition state (TS) explaining the stereoselective formation of cyclization products. Possible mechanism of the reduction of palladium(II) to palladium(0) by triethylamine (additional ligands at palladium are

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• –enantioselective protonation using α,β-unsaturated nitriles has remained unexplored for substrates other than methacrylonitrile. The Togni lab has explored using ferrocenyl tridentate nickel(II) and palladium(II) complexes as chiral Lewis acid catalysts for the hydrophosphination and hydroamination of

• and co-workers subsequently reported the hydroamination of methacrylonitrile 174 using palladium(II) catalyst 172 (Scheme 42a) [72]. Low temperature and bulky aryl groups on the catalyst were necessary to achieve good levels of enantioselectivity. In a later study, their nickel(II) catalyst 171 proved

• ) catalysts. Togni’s chiral ferrocenyl tridentate nickel(II) and palladium(II) complexes. Tomioka’s enantioselective addition of arylthiols to α-substituted acrylates. Sibi’s enantioselective hydrogen atom transfer reactions. Mikami’s addition of perfluorobutyl radical to α-aminoacrylate 11. Reisman’s Friedel

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• reactions [8]. They serendipitously discovered that palladium(II) salts catalyzed the cyclization of 1,6-enynes at much lower temperatures compared to the thermal process [9], which normally requires temperatures in excess of 200 °C (Scheme 1, path a). More recently, the same research group disclosed a CpRu

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• Takashi Nishikata Alexander R. Abela Shenlin Huang Bruce H. Lipshutz Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA 93106, USA 10.3762/bjoc.12.99 Abstract Cationic palladium(II) complexes have been found to be highly reactive towards aromatic C–H activation of

• arylureas at room temperature. A commercially available catalyst [Pd(MeCN)4](BF4)2 or a nitrile-free cationic palladium(II) complex generated in situ from the reaction of Pd(OAc)2 and HBF4, effectively catalyzes C–H activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates

• palladacycle; (2) reaction of the cationic palladacycle with an aryl iodide, arylboronic acid or acrylate, and (3) regeneration of the active cationic palladium catalyst. The reaction between a cationic palladium(II) complex and arylurea allowed the formation and isolation of the corresponding palladacycle

Bi- and trinuclear copper(I) complexes of 1,2,3-triazole-tethered NHC ligands: synthesis, structure, and catalytic properties

• Shaojin Gu,
• Jiehao Du,
• Jingjing Huang,
• Huan Xia,
• Ling Yang,
• Weilin Xu and
• Chunxin Lu

Beilstein J. Org. Chem. 2016, 12, 863–873, doi:10.3762/bjoc.12.85

• , reports concerning their preparation and use of 1,4-disubstituted-1,2,3-triazoles bearing NHC ligands are rare [22][23]. Elsevier et al. [23] reported several of palladium(II) complexes containing a heterobidentate N-heterocyclic carbene-triazolyl ligand. These palladium(II) complexes are active

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

• Vladislav Vasilenko,
• Torsten Roth,
• Clemens K. Blasius,
• Sebastian N. Intorp,
• Hubert Wadepohl and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

• donors, with distinct consequences for their coordination chemistry (vide infra). Complex synthesis In the next step of our study we set out to explore the coordination chemistry and structural properties of the synthesized ligands with rhodium(I/III), iridium(I/III) and palladium(II) precursors

Regioselective palladium-catalyzed ring-opening reactions of C1-substituted oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylates

• Michael Edmunds,
• Mohammed Abdul Raheem,
• Rebecca Boutin,
• Katrina Tait and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 239–244, doi:10.3762/bjoc.12.25

• yield of the reaction (48%, 17 h, Table 1, entry 2). The palladium catalyst, Pd(PPh3)4, gave a moderate yield (58%, 19 h, Table 1, entry 3), while the palladium(II) catalyst, PdCl2(PPh3)2, gave the best yield of the ring opened product and also reacted the fastest (88%, 16 h, Table 1, entry 4). A

• for the ring-opening reaction of 2 with aryl iodides has been proposed based on the results obtained (Scheme 5). The reaction begins with the reduction of the palladium(II) catalyst, 4, to palladium(0) 5 by zinc. The Pd(0) catalyst complexes with the aryl iodide 6 forming the palladium-aryl complex 7

Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides

• Hang Ren,
• Haoyun An,
• Paul J. Hatala,
• William C. Stevens Jr,
• Jingchao Tao and
• Baicheng He

Beilstein J. Org. Chem. 2015, 11, 2509–2520, doi:10.3762/bjoc.11.272

• and Suzuki reaction conditions. To this end, 2-(tributylstannyl)furan was coupled with 6-chloropurine nucleoside 26 by Stille cross coupling [47][48] catalyzed by bis(triphenylphosphine)palladium(II) chloride in DMF (Method I) (Scheme 3). The resulting 6-aryl compound 30 was obtained in 91% yield and

• and deprotection of 2,6-dichloropurine 42 was achieved with a saturated solution of ammonia in methanol to furnish 2-chloro-3’-deoxy-3’-fluoroadenosine (16). The 2,6-dichloro-intermediate 42 was coupled with 2-(tributylstannyl)furan catalyzed by bis(triphenylphosphine)palladium(II) chloride in DMF to

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• -2-chloro-3-cyanopyridine, which was cross-coupled with 3-methylpyridin-2-ylzinc bromide catalyzed by PEPPSI-iPr (pyridine-enhanced precatalyst preparation stabilization and initiation or 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II) dichloride) under microwave

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• evidence of the kinetic studies and the literature data, we propose the mechanistic pathway depicted in Scheme 4. The first step involves the complexation of the azo dye to palladium(II) hydroperoxide 13, followed by a peroxymetalation of the azo moiety. This then affords the pseudocyclic five membered

• cyclopalladated complexes Synthesis of (S)-chloro-[(4-isopropyloxazolinyl)-2-naphthyl](triphenylphosphine)palladium(II) (5): The complex (3) was synthesized using two methods: Method A: A mixture of Pd(OAc)2 (50 mg, 0.22 mmol, 1 equiv), AcONa (18.3 mg, 0.22 mmol, 1 equiv) and (S)-4-isopropyl-2-(naphthalen-1-yl

• -dihydrooxazol-2-yl)benzene]palladium(II) (8): Complex 8 was synthesized from 1,2-bis((S)-4-phenyl-4,5-dihydrooxazol-2-yl)benzene (7) (170 mg, 0.46 mmol, 1.01 equiv) and sodium tetrachloropalladate(II) (134 mg, 0.45 mmol, 1 equiv) in freshly distilled and thoroughly degassed methanol (5 mL). The red solution was

Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki–Heck cross-coupling reaction

• Jerzy Zakrzewski and
• Bogumiła Huras

Beilstein J. Org. Chem. 2015, 11, 1155–1162, doi:10.3762/bjoc.11.130

• Mizoroki–Heck cross-coupling reaction between 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl and iodobenzene derivatives in the presence of palladium(II) acetate coordinated with a tri(o-tolyl)phosphine ligand immobilized in a polyurea matrix. Keywords: 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1

• saturated aliphatic acids (instead of unsaturated ones as acrylates) are reacted with simple aromatic compounds (as benzene) in the presence of palladium(II) chloride [20]. Due to the important biological activity of cinnamates, the incorporation of a spin label moiety, particularly a nitroxyl fragment, is

• –i) were obtained using the coupling of 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (3) with a series of iodobenzene derivatives (4a–i) in the presence of palladium(II) acetate coordinated with tri(o-tolyl)phosphine ligand immobilized in a polyurea matrix (commercially available as

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• bisoxazolines for asymmetric aza-Michael additions. For example, Hii and co-workers reported the first example of the use of a palladium(II) complex for the aza-Michael additions of selected α,β-unsaturated N-alkenoyloxazolidinones [237] (Scheme 31). This reaction worked best when aniline was the aromatic amine

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• depicted in Figure 9 and Figure 11 were observed. Previously palladium(II)-alkyne π-complexes have been proposed as intermediates in Pd(II)-catalyzed diamination of alkynes [63], enyne coupling [64], hydroarylation of alkynes [65], inramolecular carbocyclization [66] and other reactions. Some types of

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• Compounds with an allyl, propargyl, or benzyl group as C-reagents in cross-dehydrogenative C–O coupling 4.1 Palladium- and copper-based oxidative systems Studies on the acyloxylation at the allylic position of alkenes with palladium(II) complexes started in the 1960s [213]. This type of reactions was

A novel 4-aminoantipyrine-Pd(II) complex catalyzes Suzuki–Miyaura cross-coupling reactions of aryl halides

• Claudia A. Contreras-Celedón,
• Darío Mendoza-Rayo,
• José A. Rincón-Medina and
• Luis Chacón-García

Beilstein J. Org. Chem. 2014, 10, 2821–2826, doi:10.3762/bjoc.10.299

• are tolerated. Keywords: 4-aminoantipyrine; arylboronic acids; biaryls; cross-coupling; palladium(II) complex; Introduction The sp2–sp2 carbon–carbon bond formation through cross-coupling reactions catalyzed by metal complexes has emerged as a powerful tool in organic synthesis [1][2][3][4][5][6

• their rapid transmetalation with palladium(II) complexes [11]. Although in recent years there have been numerous studies on the SM cross-coupling reaction, the necessity for a simple procedure that allows the formation of C–C bonds in functionalized substrates remains. There have been ongoing efforts to

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• )ferrocene]palladium(II) dichloride dichloromethane complex (0.22 g, 0.28 mmol) and Na2CO3 (8.78 g, 82.4 mmol) were suspended in a H2O/1,2-dimethoxyethane mixture (1:3, 75 mL), heated to 100 °C und stirred for 16 h. The resulting mixture was filtered and the filtrate was mixed with H2O (75 mL) and CH2Cl2 (75

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• alkynes 125a (Scheme 37). The regioselectivity was strongly dependent on the catalytic precursor. In the presence of palladium(0) and nickel(0) complexes the β-adduct 127a was formed as the major product. By contrast palladium(II) and nickel(II) complexes mainly gave rise to the α-adduct 126a [98][238

• catalysis (Table 16) [244]. Besides copper(I) iodide several other copper salts effectuated the reaction albeit in lower yields as did silver(I) iodide, palladium(II) chloride and platinum(II) chloride. Other transition metal catalysts such as gold(I) chloride, nickel(II) chloride and cobalt(II) chloride

Clean and fast cross-coupling of aryl halides in one-pot

• Valerica Pandarus,
• Geneviève Gingras,
• François Béland,
• Rosaria Ciriminna and
• Mario Pagliaro

Beilstein J. Org. Chem. 2014, 10, 897–901, doi:10.3762/bjoc.10.87

• following Miyaura’s discovery from 1995. He demonstrated a direct route to boronic esters [2], namely the cross-coupling of bis(pinacolato)diboron (B2Pin2) with aryl or vinyl halides catalyzed by PdCl2(dppf) ([1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloride) in the presence of excess KOAc at

Columnar/herringbone dual crystal packing of pyrenylsumanene and its photophysical properties

• Binod Babu Shrestha,
• Shuhei Higashibayashi and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2014, 10, 841–847, doi:10.3762/bjoc.10.80

• GPC to afford pure 2 (106 mg, 80%) with recovery of 3 (10.0 mg). Synthesis of 1 Iodosumanene (2) (10.0 mg, 0.025 mmol), pyreneboronic acid (7.8 mg, 0.038 mmol) and palladium(II) acetate (1.2 mg, 0.0051 mmol) were placed in a 50 mL dry test-tube. Dry acetone (8 mL) and water (4 mL) was then added. The

• , yield 80%; (b) palladium (II) acetate (20 mol %), 1-pyreneboronic acid (150 mol %), acetone/water 4:1, 40 °C, 12 h, yield 84%. Absorption, emission and quantum yield data for 1, 3 and pyrene. Supporting Information Supporting Information File 46: CIF file for the pyrenylsumanene crystal

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• , in the presence or not of the amide additive and of Cu(OAc)2 (Scheme 5). These results confirmed the indispensable involvement of these additives in the mechanism. A complementary study by Z.-J. Shi and coworkers investigated the trifluoromethylation of acetanilides also using palladium(II) and

• 2-phenylpyridine in the presence of palladium(II) catalysts (10 mol %) and starting either from 6H-perfluorohexyl bromide or perfluoroheptanoic acid [71]. Interestingly, the latter reagent provided the highest yields, and the reaction appeared to proceed through an intermediate biaryl

Palladium(II)-catalyzed Heck reaction of aryl halides and arylboronic acids with olefins under mild conditions

• Tanveer Mahamadali Shaikh and
• Fung-E Hong

Beilstein J. Org. Chem. 2013, 9, 1578–1588, doi:10.3762/bjoc.9.180

Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• complexes with iodoaniline and guanidine, respectively, (see Scheme 1) that give some clue about the reaction mechanism of the catalytic process. Results and Discussion In order to provide further support to the mechanistic proposal for the C–N insertion promoted by palladium(II) suggested by us [20], in

• with CH2Cl2 renders three solids whose combustion analysis is in accordance with the percentages expected for dichlorobis(anilino-ĸN)palladium(II) (3a–c) (see Supporting Information File 1, experimental section). IR spectra of complexes 3a–c show the characteristic absorption peaks due to the

• -iodoaniline-ĸN)palladium(II) complex recently published by us [20]. Compounds 3a–c were also characterized by solid state 13C NMR spectroscopy that gave spectra showing carbon peaks compatible with the proposed structure (see Supporting Information File 1, Figures S4–S6). After prolonging the reaction time