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

• 1 undergoing a ring-opening reaction, which used p-iodotoluene and a palladium catalyst (Scheme 2) [14]. The result was the addition of the aryl group to the unsubstituted double bond followed by dehydration to give an unsymmetrical biphenyl derivative. However, there have not been any

• oxabenzonorbornadiene with the aryl group being added to the olefin carbon furthest from the C1 substituent followed by dehydration, producing a novel, highly-substituted, biphenyl derivative. Results and Discussion The optimization study focused on the palladium catalyst, Lewis acid additive and solvent, as the

• 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

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• summary, after a four step synthesis route, the total yield of 3d from 8 was 36%. Attempts were made to convert alkyne 4d into the corresponding alkene 4c. However, partial hydrogenations with a Lindlar catalyst [23] or with trimethylsilane using a palladium catalyst [24] were either unsuccessful or

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• -pot procedure, enynes could be synthesized by introducing a second alkyne and a palladium catalyst to perform a tandem carbohalogenation/Sonagashira coupling. Conclusion Copper catalysis has recently emerged as a new means of harnessing the potential of alkyl radicals in catalytic alkylation chemistry

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

• phosporus pentachloride to prepare 4-chloro-8-methoxy-5-nitroquinoline and secondly with triflate anhydride, dimethylaminopyridine, and 2,6-lutidine to prepare 8-methoxy-5-nitro-4-triflylquinoline. The Suzuki cross-coupling was carried out on both quinoline derivatives in the presence of a palladium

• catalyst and the appropriate organoborane to give the expected product with 47 and 78% yield for the chloride and triflate substrates, respectively. The nitro function present in the product was then reduced by palladium-catalyzed hydrogenation to yield the amine product converted into a diazonium salt. A

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

• -tetramethylpiperidine-1-oxyl (3) with iodobenzene (4a) and 4-methyliodobenzene (4b) were used as the test reactions to check the effectiveness of various palladium catalyst systems. The use of Pd(OAc)2/Ph3P/Bu3N [37] resulted in a low yield of the target products. No products were obtained when other catalyst systems

Radical-mediated dehydrative preparation of cyclic imides using (NH₄)₂S₂O₈–DMSO: application to the synthesis of vernakalant

• Dnyaneshwar N. Garad,
• Subhash D. Tanpure and
• Santosh B. Mhaske

Beilstein J. Org. Chem. 2015, 11, 1008–1016, doi:10.3762/bjoc.11.113

• absence of a palladium catalyst and without the need of inert atmosphere or Schlenk tube, however, the presence of both APS and DMSO was necessary. Optimization of the protocol using various permutations and combinations provided the ideal reaction conditions for imide synthesis (Table 1, entry 9). To the

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

• Masashi Hasegawa,
• Junta Endo,
• Seiya Iwata,
• Toshiaki Shimasaki and
• Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

• various types of aryl groups. At this point, we have chosen the direct arylation of TTF in the presence of a palladium catalyst as a key reaction for the chiral polymer synthesis (Scheme 2) [22]. Thus, the chiral allenes, (R)-9 or (S)-9, react with an active palladium species, prepared in situ from Pd(OAc

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• reaction we used a palladium catalyst and a copper(I) cocatalyst in the presence of triphenylphosphine and triethylamine as the base. The carboxylic acids were then submitted to a gold-catalyzed cyclization reaction (Table 2). The optimized reaction conditions for cyclization was employed for pyrrole- and

Weakly nucleophilic potassium aryltrifluoroborates in palladium-catalyzed Suzuki–Miyaura reactions: relative reactivity of K[4-RC₆F₄BF₃] and the role of silver-assistance in acceleration of transmetallation

• Vadim V. Bardin,
• Anton Yu. Shabalin and
• Nicolay Yu. Adonin

Beilstein J. Org. Chem. 2015, 11, 608–616, doi:10.3762/bjoc.11.68

• [C6F5BF3] retards toward K2CO3 [39] as well as K2CO3 in a mixture with catalytic amounts of Pd(OAc)2 in refluxing MeOH [19]. Resistance of K[C6F5BF3] (1a) towards K2CO3 and Ag2O in toluene (without palladium catalyst and phosphine ligand) is confirmed by stirring the corresponding suspensions at 100 °C for

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• methods. To address these disadvantages, in the last decade particular attention was given to the replacement of the expensive palladium catalyst, for instance by iron [37]. However, major impact was made by introduction of the cheap and environmentally friendly intramolecular homolytic aromatic

Exploration of C–H and N–H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines

• Michael Ghobrial,
• Marko D. Mihovilovic and
• Michael Schnürch

Beilstein J. Org. Chem. 2014, 10, 2186–2199, doi:10.3762/bjoc.10.226

• inexpensive palladium catalyst. Even though these conditions were not tested on 1-arylindoles such as 5 we expected good results from this procedure and these results are summarized in Table 6. Considering the aryl donors, excellent yield of products 8 were obtained in case of phenyl (5a, 96%, Table 6, entry

Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

• Miroslav Palík,
• Jozef Kožíšek,
• Peter Koóš and
• Tibor Gracza

Beilstein J. Org. Chem. 2014, 10, 2077–2086, doi:10.3762/bjoc.10.216

• Pd-cyclisation of unsaturated polyols in the presence of a strong base or a high oxidation state palladium catalyst. The PdII–PdIV-catalysed transformation toward the bicyclisation product proceeded only on the O-silyl-protected triol 12. The PdII-cyclisation of terminal olefinic substrates in the

Hindered aryl bromides for regioselective palladium-catalysed direct arylation at less favourable C5-carbon of 3-substituted thiophenes

• Rongwei Jin,
• Charles Beromeo Bheeter and
• Henri Doucet

Beilstein J. Org. Chem. 2014, 10, 1239–1245, doi:10.3762/bjoc.10.123

• desired 5-arylation products in moderate to good yields using only 0.5 mol % of a phosphine-free and air-stable palladium catalyst. Then, from these 5-arylthiophenes, a second palladium-catalysed C–H bond functionalization at C2 of the thiophene ring allows the synthesis of 2,5-diarylthiophenes with two

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

• ). Another example of a C(sp3)–P cross-coupling was reported by Lanteri et al. [55]. A palladium catalyst effectuated the coupling of n-Bu3SnPPh2 (30) with several perfluoroalkyl iodides 31 (Scheme 8). The stannane 30 was in situ generated by the reaction of the diphenylphosphide anion with n-Bu3SnCl. After

• [158]. The article included one example with vinyl triflate 76 as a substrate (Scheme 21). The vinyl electrophile 76 was activated by the presence of the carbonyl group so the reaction also took place without a palladium catalyst albeit in lower yield (60%) and with formation of byproducts. Julienne et

• performed with a palladium catalyst in the presence of a weak base. Sometimes microwave irradiation was used to shorten the reaction time. Gilbertson et al. have converted a series of vinyl triflates 80b into the corresponding vinyl phosphine boranes 81b through palladium catalysis with HPPh2 (Table 9) [160

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• . Such a compound can be synthesized by replacing the bromo group of 28 with a 2,6-dimethyl substituted phenyl group (Scheme 10). The Suzuki coupling was again employed; compound 28 underwent the coupling reaction with 2,6-dimethylphenylboronic acid in the presence of a palladium catalyst [Pd(PPh3)4] and

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

• . There is no need to isolate the intermediate boronic acid pinacol ester, while the air stable sol–gel entrapped palladium catalyst does not require the use of inert conditions. Finally, the use of isopropanol or 2-butanol as reaction solvents further points out the environmental benefits of the method

Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

• Andrea Caporale,
• Stefano Tartaggia,
• Andrea Castellin and
• Ottorino De Lucchi

Beilstein J. Org. Chem. 2014, 10, 384–393, doi:10.3762/bjoc.10.36

• complicates the recycling of the palladium catalyst since the two metals are difficult to separate. Sonogashira reactions can be used for the syntheses of terminal alkynes from aryl halides through the coupling with an alkyne source such as trimethylsilylacetylene (TMSA) or 2-methyl-3-butyn-2-ol (4) in

• generality of this protocol. It is also worth noting that these conditions are also highly practical and well suited to scale-up the reaction, since inexpensive 4 can be efficiently coupled with aryl bromides instead of iodides by using common solvents and ligands for the palladium catalyst. The copper-free

• the acetylenic proton of 5 was necessary. Analogously to acetylene [80][81], the protection of propiolic acid with acetone was carried out in presence of an excess of KOH (6.0 equiv) at room temperature (Scheme 2). The screening of the optimal palladium catalyst for the Pd-catalyzed coupling reaction

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

• liberates the palladium catalyst. Experiments carried out by the authors were inconsistent with an alternative purely free radical pathway, but could not rule out caged and/or “Pd-associated” radical intermediates. Another study by Y. H. Budnikova et al. described the electrochemical perfluoroalkylation of

Consecutive cross-coupling reactions of 2,2-difluoro-1-iodoethenyl tosylate with boronic acids: efficient synthesis of 1,1-diaryl-2,2-difluoroethenes

• Ju Hee Kim,
• Su Jeong Choi and
• In Howa Jeong

Beilstein J. Org. Chem. 2013, 9, 2470–2475, doi:10.3762/bjoc.9.286

• more soluble Cs2CO3 resulted in the formation of 4a in 61% yield. Increasing the reaction temperature did not improve the of yield of 4a. We also examined the effect of the palladium catalyst in this reaction. Therefore, the same reaction was performed in the presence of 5 mol % of Pd(PPh3)2Cl2 instead

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• an encapsulated palladium catalyst by Baxendale and Ley, et al. [25], the latter to process multigram quantities in a microwave-assisted Suzuki–Miyaura coupling. A comparison on the use of palladium(0) nanoparticle catalysts on glass-polymer composite materials in batch and flow-through experiments

Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst

• Cybille Rossy,
• Eric Fouquet and
• François-Xavier Felpin

Beilstein J. Org. Chem. 2013, 9, 1426–1431, doi:10.3762/bjoc.9.160

• , activated-charcoal-supported palladium catalyst for hydrogenation and debenzylation [33]. This homemade Pd/C catalyst was prepared by impregnation of activated charcoal by the reduction of Pd(OAc)2 in MeOH under an atmosphere of H2 (1 atm). With these previous results in mind, we reasoned that the

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• exchange and the subsequent transmetalation to zinc, and then used directly in one pot (Table 3). Lautens reported enantioselective carbozincation of alkenes using a palladium catalyst with a chiral ligand (Scheme 23) [93]. Treatment of 3g with diethylzinc in the presence of catalytic amounts of palladium

Palladium-catalyzed C–N and C–O bond formation of N-substituted 4-bromo-7-azaindoles with amides, amines, amino acid esters and phenols

• Rajendra Surasani,
• Dipak Kalita,
• A. V. Dhanunjaya Rao and
• K. B. Chandrasekhar

Beilstein J. Org. Chem. 2012, 8, 2004–2018, doi:10.3762/bjoc.8.227

• amides, amines and amino acid esters takes place rapidly by using the combination of Xantphos, Cs2CO3, dioxane and palladium catalyst precursors Pd(OAc)2/Pd2(dba)3. The combination of Pd(OAc)2, Xantphos, K2CO3 and dioxane was found to be crucial for the C–O cross-coupling reaction. This is the first

• report on coupling of amides, amino acid esters and phenols with N-protected 4-bromo-7-azaindole derivatives. Keywords: 7-azaindole; C–N bond; C–O bond; ligand; palladium catalyst; Introduction Palladium-catalyzed C–N and C–O bond-forming reactions between 4-substituted 7-azaindoles and amides, amines

• ). There was no reaction without the N-protection (Table 4, entry 1). Heating of the reaction mixture of 4-bromo-1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridine (1b) with phenylmethanamine (4a) in the presence of base and palladium catalyst resulted in the desulfonated 4-bromo-7-azaindole as the sole product

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• preferred which is more in accordance with previous observations and a specific directed nitrogen-chelating effect (Scheme 20). Thus, C2-selectivity may arise from a prior interaction of the palladium catalyst with nitrogen. The coordination of oxazole to arylpalladium(II) complex may lower the pKa of

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• with imines. Arndtsen and coworkers developed a new highly active palladium catalyst to improve previous results in this area. Moreover, this strategy allows the selective incorporation of two different imines leading to polysubstituted imidazoliniums 13. After a large screening of palladium

• the intermediacy of α,β-alkynyl ketones in the four-component process could not be confirmed (TLC). In addition, their reaction with hydrazines was shown to be ineffective under the present solvent system in the presence or absence of palladium catalyst. This may suggest that if α,β-alkynyl ketones

• basic media. A subsequent Pd-mediated intermolecular alkylation with the dihalogeno substrate followed by an intramolecular N-arylation furnished 2-substituted indoles 68. In this cascade reaction, the palladium catalyst intervenes in three different coupling reactions: Intermolecular N-alkenylation, C