The first Pd-catalyzed Buchwald–Hartwig aminations at C-2 or C-4 in the estrone series

• Ildikó Bacsa,
• Dávid Szemerédi,
• János Wölfling,
• Gyula Schneider,
• Lilla Fekete and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 998–1003, doi:10.3762/bjoc.14.85

• A facile Pd-catalyzed C(sp2)–N coupling to provide a range of 2- or 4-[(subst.)phenyl]amino-13α-estrone derivatives has been achieved under microwave irradiation. The reactions were mediated with the use of Pd(OAc)2 as a catalyst and KOt-Bu as a base in the presence of X-Phos as a ligand. The

• derivative [17][18]. The C(sp2)–N cross-coupling of the triflate was achieved with benzophenone imine or benzylamine. The removal of the protecting groups resulted in 3-aminoestrone in high yields. Schön et al. developed two convenient protocols for the preparation of 3-aminoestrone using Pd(OAc)2 and Pd2

• results [18][20], we started to optimize the reaction conditions for the transformation of 2-bromo-13α-estrone 3-methyl ether (1) with aniline (Table 1). Since the Pd source has been shown to be crucial in the amination step, two Pd catalysts were investigated. Namely, Pd(OAc)2 and Pd2(dba)3 were used in

Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib

• Jingbo Yu,
• Zikun Hong,
• Xinjie Yang,
• Yu Jiang,
• Zhijiang Jiang and
• Weike Su

Beilstein J. Org. Chem. 2018, 14, 786–795, doi:10.3762/bjoc.14.66

• in Supporting Information File 1). Subsequently, the optimization was carried out to improve the performance of the reaction. Palladium catalysts and ligands were firstly screened, which showed Pd(OAc)2/PPh3 as the most efficient catalyst system (Table 1, entry 5). The catalyst loading could be

• reagent in the reaction, the substrate 1a was converted to 4a in 27% yield (conditions a), while the dehalogenation was exacerbated in the presence of Pd(OAc)2/PPh3 (conditions b). This phenomenon was in agreement with previous reports [14][15][16], that Pd-catalyzed homocoupling of aryl halides under

• protocol was conducted in a total mechanosynthesis of axitinib in short reaction time and high efficiency. With this system, we hope to expand the pharmaceutical synthetic toolbox in mechanochemistry. Investigation of additives in the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), Pd(OAc)2 (5 mol %), PPh3

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• process, as 200 ppm of Pd(OAc)2 worked like a co-catalyst being beneficial either for the reaction rate and the yields, and no product was observed without the Pd source. Furthermore, the recyclability of the catalyst was improved and the experiments could be repeated up to 5 runs with yields >90

• reference [67]. Suzuki−Miyaura couplings with, or without, ppm Pd. Conditions: ArI 0.5 mmol 3a, Ar’B(OH)2 (0.75–1.00 mmol, 1.5–2.0 equiv) 3b, *with 200 ppm of Pd(OAc)2. Adapted from reference [70]. Copyright 2016 American Chemical Society. Cascade reaction with GOx and Myo. Adapted from reference [82

Palladium-catalyzed ortho-halogenations of acetanilides with N-halosuccinimides via direct sp² C–H bond activation in ball mills

• Zi Liu,
• Hui Xu and
• Guan-Wu Wang

Beilstein J. Org. Chem. 2018, 14, 430–435, doi:10.3762/bjoc.14.31

• ortho-halogenations in detail. Results and Discussion To begin our study, N-(p-tolyl)acetamide (1a) was chosen as the model substrate to react with NIS using Pd(OAc)2 as the catalyst to optimize reaction parameters such as additive, reaction time and reagent ratio. The reaction of 1a (0.4 mmol) with NIS

• (0.4 mmol) was initially performed under the catalysis of Pd(OAc)2 (10 mol %) in a Spex SamplePrep 8000 mixer mill at a frequency of 875 cycles per minute at room temperature for 3 h. Unfortunately, the desired iodinated product was not detected (Table 1, entry 1). Then, various acids were examined

• reaction of 1a with NIS in the absence of Pd(OAc)2, yet still with PTSA as the promoter, and no iodinated product was furnished (Table 1, entry 3). The use of D-camphorsulfonic acid (D-CSA) or mesitylenesulfonic acid dihydrate provided inferior results than that obtained in the presence of PTSA (Table 1

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• -ketoesters and phenols (the Pechmann condensation) [17]. Recent studies for the metal-catalyzed reactions for the synthesis of the coumarin skeleton are as follows: the Yb(OTf)3-catalyzed microwave irradiation of phenols and propynoic acids [18], the Pd(OAc)2-catalyzed oxidative cyclocarbonylation of 2

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• ]pyridines 32 and 34 (Scheme 5). In situ cyclocondensation of β-halovinyl aldehydes 29 with 5-aminopyrazoles (R = Ph, 16) under Heck conditions in the presence of Pd(OAc)2 with xantphos (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) gave 6-substituted pyrazolo[3,4-b]pyridines 34. On the other hand

• high regioselectivity. Working on similar lines Boruah et al. [49] further explored the reactivity of 5-aminopyrazoles 16 with β-halovinyl/aryl aldehydes 33 under conventional heating and microwave conditions in DMF and DMSO with Pd(OAC)2 (2.5 mol %) catalyst with PPh3 as ligand (Scheme 5

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations

• Aymen Skhiri,
• Ridha Ben Salem,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2017, 13, 2862–2868, doi:10.3762/bjoc.13.278

• heteroarylations with a variety of heteroarenes using a phosphine-free palladium catalyst. Results and Discussion First, we examined the influence of the reaction temperature, using DMA as solvent, KOAc as base and 2 mol % Pd(OAc)2 as catalyst (Table 1). We had previously observed that these reaction conditions

• temperature (110–130 °C), 2-bromoselenophene seems to afford larger amounts of selenophene oligomers as side-products. The use of PdCl2 or PdCl(C3H5)(dppb) as catalysts instead of Pd(OAc)2 or other bases such as K2CO3, Cs2CO3, CsOAc or NaOAc afforded 1 in lower yields (Table 1, entries 4–9). The influence of

• two other solvents in this cross-coupling reaction was also examined. We observed that both DMF and xylene in the presence of 2 mol % Pd(OAc)2 catalyst with KOAc gave 1 in moderate yields (Table 1, entries 10 and 11). Then, we investigated the scope of the coupling of 2-bromoselenophene with a set of

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• compounds under palladium catalysis [28][29][30][31][32][33][34][35]. Disappointingly, an attempted cyclization of 3a employing one of the established precatalyst cocktails – Pd(OAc)2, Ph3P, NaH in dioxane – virtually failed. The target product 4 could be detected in the reaction mixture by 1H NMR

• sulfonamides 8d–g in good yields (Scheme 3). Next, the key step in the targeted synthesis, the intramolecular Pd-catalyzed arylation was optimized for the sulfonamide 8a (Table 1). Initially the studied reaction was performed in dioxane at 90 °C employing 5 mol % of Pd(OAc)2, 20 mol % of Ph3P, and 4.0

• conversion was lower and so was the yield. With a lower amount of the precatalyst (1 mol % of Pd(OAc)2 and 4 mol % of Ph3P) the sultam 10a was formed in an extremely low yield of 4% (Table 1, entry 7). Finally, when keeping the mixture at 90 °C for only 30 min instead of 1 h, a virtually quantitative

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• of their low reactivity. Recently, Li and Su with co-workers have developed a liquid-assisted grinding (LAG) method for the Suzuki–Miyaura coupling between aryl chlorides and boronic acids to synthesize the biaryls in nearly quantitative yield. Under optimized conditions 2 mol % Pd(OAc)2 and 4 mol

• palladium salts (Pd(OAc)2 or Pd(PPh3)4) and DABCO (1,4-diazabicyclo[2.2.2]octane) various acetylenes and aryl halides were coupled to obtain the Sonogashira coupling products in excellent yields (near quantitative, Scheme 10a). The reactions were reported for aliphatic alkynes as well. In Scheme 10b, an

• . They have also demonstrated a mechanochemical synthesis of 3-vinylindoles and β,β-diindolylpropionates by C–H activation. Substituted indoles and ethyl acrylates were reacted in presence of 10 mol % of Pd(OAc)2 and 1.2 equiv of MnO2 to afford highly substituted 3-vinylindoles using silica gel and

Pd(OAc)₂/Ph₃P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles

• Dominik Kellner,
• Maximilian Weger,
• Andrea Gini and
• Olga García Mancheño

Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175

• procedure towards the tail-to-tail dimer using readily available Pd(OAc)2 and inexpensive triphenylphosphine as ligand. Furthermore, simple screw cap vials are employed, allowing carrying out the reaction at low pressure. In addition, the potential of the dimer as a chemical platform for the preparation of

• using 2 mol % of Pd(OAc)2, Pd(Ph3P)2Cl2 or Pd(Ph3P)4 as catalyst in the presence of 10 mol % Et3N as base in THF at 90 °C in a sealed Schlenk tube was initially explored. However, a low conversion into the tail-to-tail 2-TT (2% yield for Pd(OAc)2) or only traces (for the other two catalysts) of the

• desired linear dimers 2 could be detected (Table 1, entries 1–3). Based on the previous reported work on the dimerization of 1,3-butadiene and isoprene, in which monodentated ligands were employed, the Pd(OAc)2/Ph3P/Et3N (1:3:10) catalytic system was next explored. This combination led to a significant

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• of the coupled products with unacceptable Pd species led to a hard separation and recycling of homogeneous catalyst systems. In our previous study [4] we reported a ball-milling Heck reaction catalyzed by Pd(OAc)2. Although the catalyst showed the satisfactory reactivity, it was difficult to recover

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• , benzothiazole and N-methylimidazole was studied in the presence of three alternative catalytic systems: Pd(dba)2/DavePhos/Cs2CO3, Pd(PPh3)4/PivOH/K2CO3 and Pd(OAc)2/Cu(OAc)2/PPh3/K2CO3. The first catalytic system was found to be successful in the reaction with benzoxazole, the second one was less efficient for

• using the Pd(OAc)2/DavePhos/PivOH catalytic system (DavePhos = 2-dicyclohexylphosphine-2’-dimethylaminobiphenyl, PivOH = t-BuCOOH) [26][27], and also bromo derivatives of condensed aromatic compounds were employed in this process [28]. The results of the Osuka group and other researchers in this field

• Zinc meso-(4-bromophenyl)porphyrinate (1) was chosen as a model substrate for the investigation of the conditions of the catalytic arylation. The reaction with benzothiazole was first catalyzed with Pd(OAc)2/DavePhos (2-dicyclohexylphosphino-2’-dimethylaminobiphenyl) (20:20 mol %) and carried out in

Synthesis of the heterocyclic core of the D-series GE2270

• Christophe Berini,
• Thibaut Martin,
• Pierrik Lassalas,
• Francis Marsais,
• Christine Baudequin and
• Christophe Hoarau

Beilstein J. Org. Chem. 2017, 13, 1407–1412, doi:10.3762/bjoc.13.137

• led to the fair production of the expected trithiazolylpyridine 9 but in moderate 46% yield. Nevertheless, an additional screening of palladium sources has revealed that Pd(OAc)2 was a better pre-catalyst to perform quantitatively the first borylation-step in short reaction time (1 h) and to achieve

• sequence to build and introduce both thiazole units to the picolinamide 5 (Scheme 1). Pleasingly, the application of the optimized BSC procedure based upon the use of Pd(OAc)2 as pre-catalyst allowed to achieve the cross-coupling of picolinamide 5 with methyl(4-bromothiazol-2-yl)ketone (8), providing the

• -series GE2270 and our present one. Synthesis of trithiazolylpyridine 9. Reaction conditions: a) Pd(OAc)2 (5 mol %), CyJohnPhos (10 mol %), Cs2CO3 (2 equiv), DMF, 110 °C, 18 h, 69%. b) UHP (2 equiv), TFAA (2.1 equiv), ACN, 0 °C, 1 h, quantitative. c) POCl3 (2 equiv), toluene/DMF, 0 °C, 1 h, 83%. d) NH4OH

Synthesis of novel 13α-estrone derivatives by Sonogashira coupling as potential 17β-HSD1 inhibitors

• Ildikó Bacsa,
• Rebeka Jójárt,
• János Wölfling,
• Gyula Schneider,
• Bianka Edina Herman,
• Mihály Szécsi and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2017, 13, 1303–1309, doi:10.3762/bjoc.13.126

• phenylacetylene using Pd(OAc)2 and CuI as catalysts [21]. They did not investigate the influence of the nature of the substituent on the phenyl ring of the acetylene on the course of the reactions. They carried out the full saturation of the C≡C bond of the 2-phenethynyl estrone with palladium on charcoal

• semihydrogenation of different arylacetylenes using Pd(OAc)2 or Pd(PPh3)2Cl2 as the catalyst and DMF/KOH as a hydrogen source, under conventional heating [30]. The first catalyst afforded cis-alkenes in high yields with excellent chemo- and stereoselectivity. The latter catalyst displayed lower catalytic activity

• the modified procedure of Li et al. using Pd(OAc)2 or Pd(PPh3)2Cl2 as a catalyst, and DMF/KOH as a hydrogen source, in a microwave reactor. The cis-alkene 13 and the trans-alkene 15 were formed chemo- and stereoselectively under the applied conditions. The different stereochemical outcome of the

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• cyclocondensation and the desired products were obtained in excellent yields [77]. Other systems such as Pd(OAc)2/THF [78], D301R (a tertiary amine-functionalized ion-exchange resin)/biphenyl [79], and diethylamine/NaOH/H2O [80] were also successfully employed in this transformation. Despite all these successes

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• yields. In 2015, Ghorbani-Choghamarani and co-workers designed a new type of nanocatalyst MCM-41-dzt-Pd through the immobilization of Pd(OAc)2 on the surface of dithizone(dzt)-functionalized mesoporous MCM-41 (Scheme 6) [26]. The developed catalyst was able to convert aryl halides to the corresponding

• Pd(OAc)2 as catalyst and molecular oxygen as oxidant, however, the reaction suffered from low yield (2.3%) [49][50]. In 1997, Seo and co-workers reported an iron-HPA (heteropoly acid)-complex-catalyzed protocol for oxidation of benzene to phenol [51]. In 2005, the Rybak-Akimova group reported that

• at other positions. In 2015, Sun and co-workers developed a Pd(OAc)2 catalyzed ortho-hydroxylation of 2-arylpyridines using tert-butyl hydroperoxide (TBHP) as oxidant [62]. The reaction was carried out at 115 °C in 1,2-dichloroethane (DCE), affording the corresponding phenols in moderate to good

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• 7a with 8 or 9 in dimethylacetamide in the presence of Pd(OAc)2, Bu4N+Br− and K2CO3, led to inseparable mixtures. Further, compounds 7d–g could not be isolated when the base K2CO3 was replaced with Cs2CO3 and PPh3 was used as a ligand [27]. Gratifyingly, the 5'-arylated products 7d–g were obtained by

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

• includes the C–H activation. 1: starting material, 1∙HOAc: coordinated starting material, Pd(OAc)2: catalyst, 2: product, PhI(OAc)2: oxidant. Details of information considered as a priori knowledge in this study and source of this knowledge. Results of the MBDoE for kinetic parameters, showing the number

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

• transformation was considerably improved when an alternative coupling protocol (Pd(OAc)2, PPh3, CuI in NEt3/DMF) was employed, the yield was significantly enhanced and the coupling product anti-6 was obtained in 59% yield. Sonogashira couplings of 4-benzyloxy- and 4-(2-trimethylsilyl)ethoxy-substituted 1,2

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

• dibromobenzoic acid with sulfuric acid in methanol) with an excess of anilines in the presence of cesium carbonate and catalytic quantities of Pd(OAc)2 and BINAP were processed smoothly. The desired methyl 2,4-dianilinobenzoates (2a–e) were obtained in good to excellent yield. In a parallel synthesis, using the

• Pd(OAc)2 in AcOH at 110 °C under air (Table 1, entries 1 and 2). To our delight, the desired product could be formed without observing any byproduct, and the adoption of NaOt-Bu as base gave a better yield. We next replaced the acetic acid with other acidic solvents. The desired transformation could

• materials. The operational simplicity combined with the convenience for introducing substituents to the aromatic rings makes this method useful. Natural indolo[3,2-a]carbazole alkaloids. Retrosynthetic analysis of indolo[3,2-a]carbazoles. Reagents and conditions: (a) H2SO4, MeOH; (b) Ar-NH2, Pd(OAc)2, BINAP

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• to catalyze these reactions by coordination with the hydroxy moiety, thereby increasing its leaving group ability [23][24][25][26][27][28]. Recently, Tamaru and co-workers have intensively investigated the use of triethylborane as an additive with either Pd(PPh3)4 or Pd(OAc)2 as catalysts for the

• further used as synthetic intermediates in numerous synthetic routes to heterocyclic compounds and molecules of biological interest [41][42]. Results and Discussion We first investigated the allylation of diethyl malonate (2a) with the allylic alcohol 1a in DMF in the presence of Pd(OAc)2 (10 mol %), PPh3

• optimized conditions (Table 1, entry 4), we examined the scope of the catalytic system, Et3B/ Pd(OAc)2/PPh3, for a wide range of 1,3-dicarbonyl compounds and related derivatives (pKa = 9–14) [29][31] using two typical MBH alcohols 1a and 1b. The results of this study are summarized in Table 2. Like diethyl

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• , K3PO4 (2 M), 80 °C, 16 h, ii) ICl, DCM, 0 °C or NIS, 50:50 CHCl3/CH3CO2H, rt, 2 h. Synthesis of the bithiophene through palladium catalyzed direct arylation, a) i) Pd(OAc)2, PCy3, PivOH, K2CO3, toluene 100 °C, 4 h, 1%, ii) Pd(OAc)2, PPh3, K2CO3, DMF 120 °C, 6 h, 10%, iii) Pd(OAc)2, dppp, KOAc, DMAc 120

• °C, 5 h, 32%, iv) Pd(OAc)2, dppb, KOAc, DMAc 120 °C, 5 h, 32%. Synthesis of the key bis-borylated BDT core 13, i) 1.5 equiv B2Pin2, 0.025 equiv [Ir(COD)OMe]2, 0.05 equiv t-Bu2bipy, DME, 80 °C, 2 h. Synthesis of the BXR and BTXR series of materials, i) 5-bromothiophene carboxaldehyde, 5b, 7a–c, 9b, or

Regiocontroled Pd-catalysed C5-arylation of 3-substituted thiophene derivatives using a bromo-substituent as blocking group

• Mariem Brahim,
• Hamed Ben Ammar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2016, 12, 2197–2203, doi:10.3762/bjoc.12.210

• conditions in terms of number of steps, base nature, use of a phosphine-free catalyst at low loading and a quite “atom economic” aryl source promoting such a C5-arylation using C3-substituted 2-bromothiophenes. We report i) that only 1 mol % of air-stable Pd(OAc)2 catalyst associated to KOAc promotes the

• phosphine-free Pd(OAc)2 catalyst performed at 110 °C, only afforded the desired product 1 in a trace amount, but a complete conversion of 2-bromothiophene was observed, revealing the high reactivity of the thienyl C–Br bond under these conditions (Table 1, entry 1). Using a lower reaction temperature of 80

• , respectively; whereas, a very short reaction time of 0.5 h led to a lower yield of 27% due to the poor conversion of 4-bromonitrobenzene (Table 1, entries 3–6). The use of 0.5 mol % Pd(OAc)2 catalyst at 80 °C during 2 h also afforded 1 in a lower yield of 35%. Again, a large amount of 4-bromonitrobenzene was

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