Regioselective Pd-catalyzed direct C1- and C2-arylations of lilolidine for the access to 5,6-dihydropyrrolo[3,2,1-ij]quinoline derivatives

• Hai-Yun Huang,
• Haoran Li,
• Thierry Roisnel,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2019, 15, 2069–2075, doi:10.3762/bjoc.15.204

• heteroaromatics [38], we initially employed 1 mol % Pd(OAc)2 catalyst associated to KOAc as the base in DMA at 150 °C as the reaction conditions to promote the coupling of lilolidine with 3-bromobenzonitrile (Table 1, entry 1). Under these conditions a mixture of the α- and β-arylated lilolidines 1a and 1b was

• obtained in a 64:36 ratio. Then, the influence of some bases on the regioselectivity with Pd(OAc)2 catalyst was examined. With CsOAc a similar regioselectivity than with KOAc was obtained, whereas the use of NaOAc afforded the products 1a and 1b in an 85:15 ratio, but with a moderate conversion of 3

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

• for efficient syntheses of IPs [20]. In recent years much attention has been paid towards the exploration of transition metals (TMs) as homogeneous as well as heterogeneous catalytic system like Pd(OAc)2 [21], CuI [22], ZnO [23], ZnI2 [24], Cu(OTf)2 [25], Sc(OTf)3 [26], RuCl3 [27], [Cp*RhCl2]2 (Cp

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

• for [3 + 2] C–C/N–C bond-forming annulation [31], the first tests were performed with the following two catalytic systems: [Pd(η3-C3H5)Cl]2 (5 mol %), dppf (15 mol %)], and [Pd(OAc)2 (10 mol %), dppb (15 mol %)] in THF at room temperature (Table 1, entries 1 and 2). These conditions promptly (ca. 1

• hour) generated annulated product 4a arising from C-allylation (C–C bond forming)/intramolecular O-Michael addition (O–C bond forming) sequence. The purification of the crude reaction was easier using the Pd(OAc)2 and dppb system (Table 1, entry 2), which was thus chosen to continue the optimization

• ). The above work allowed obtaining the optimal reaction conditions for the generation of the furocycloalkanone 4a [Pd(OAc)2 (10 mol %), dppb (15 mol %) in DMSO, 1 h at rt (conditions A)] as well as for the formation of the bicyclo[4.3.0]nonane-3,8-dione (5a) [Pd(OAc)2 (10 mol %), dppb (15 mol %) in DMSO

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• azobenzene [58]. The cyclopalladation process was proved to be a highly regioselective process and the observed palladation rate was faster compared to the conventional solution-phase method. An equimolar amount of 4'-(N,N-dimethylamino)-4-nitroazobenzene and Pd(OAc)2 in the presence of 25 μL of glacial

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• (PPh3)4/PPh3 as the catalyst, Cs2CO3 as base, and dimethyl formamide (DMF) as solvent at 105 °C for 10 h under N2 atmosphere. Meanwhile, different pallladium species were tested in this reaction system. It was found that Pd(OAc)2 was the most effective palladium catalyst, and the desired product y-1 was

• (1a, 3.0 mmol, 1.0 equiv, 0.654 g), 2-bromo-4,5-dimethoxybenzoyl chloride (3.6 mmol, 1.2 equiv, 1.006 g), and norbornadiene (6.0 mmol, 2.0 equiv, 0.553 g) was performed in the presence of 0.15 mmol of Pd(OAc)2, 0.375 mmol of PPh3 and 6.75 mmol of Cs2CO3 at 105 °C in DMF under N2 for 30 h, the desired

• with aryl iodide (0.30 mmol, 1.0 equiv), ortho-bromobenzoyl chlorides (0.36 mmol, 1.2 equiv), norbornadiene (0.60 mmol, 2.0 equiv), Pd(OAc)2 (5 mol %), triphenylphosphine (12.5 mol %), Cs2CO3 (0.675 mmol, 2.25 equiv), and DMF (4 mL). The mixture was stirred at 105 °C under nitrogen atmosphere for 10 h

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

• vinyl ethers 15 [13][44][45][46]. We found that the best yields were obtained using Pd(TFA)2 and n-butyl vinyl ether as solvent in the presence of bathophenanthroline as ligand. In the case of Pd(OAc)2, the reaction was slower with moderate yields. The ring-closing metathesis reaction was performed with

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• Pd sources, namely Pd(PPh3)4 or Pd(OAc)2 were used, the latter without the addition of any mono- or bidentate P-ligand. Although Et3N can usually be used successfully, the dealkylation of the phosphite reagent may occur. In order to avoid this unwanted side reaction, K2CO3 was also involved in

• [29]; namely, 1 equiv in the case of Pd(PPh3)4 and 1.3 equiv when using Pd(OAc)2. It was earlier established that in the microwave-assisted Pd(II)-catalyzed C–P coupling of aryl bromides and dialkyl phosphites, an excess of the applied dialkyl phosphite may serve as phosphorus ligand and reducing

• the yields of the C–P couplings. Reactions with catalyst precursor Pd(OAc)2 gave the desired phosphonate 8a in moderate yields (Table 1, entries 1–8). Starting from 2-iodo compound 1I, dehalogenation, an unwanted side reaction occurred, in particular, at elevated temperature (Table 1, entries 3, 4, 7

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

• derivative 134 was realized in the presence of a Pd(OAc)2 catalyst with the aid of the ligand cataCXium A (135) to generate the macrocyclic product 136. Eventually, synthesis of MK-6325 (141) was achieved by adopting saponification followed by amidation (Scheme 20). Conclusion In this review, we have

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• . Experimentally, 3Pd can be formed quantitatively by simply mixing Pd(OAc)2 with a CH2Cl2/MeOH solution of 3 at room temperature. This transformation is confirmed by MS with a parent-ion peak at m/z = 1015.24 (calcd for C64H46BN6Pd, [M]+ = 1015.29). In the 1H NMR spectrum of 3Pd (Figure 3), no signals are

• air, rt, overnight; (iii) Pd(OAc)2 (3 equiv), CH2Cl2/MeOH 5:1, rt, overnight. Supporting Information Supporting Information File 304: Experimental part. Supporting Information File 305: Crystallographic information file of compound 3. Supporting Information File 306: Crystallographic information file

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• (PPh3)4 as catalyst, no conversion was observed, whereas the reaction could be achieved with Pd(OAc)2 as a catalyst and water as a solvent (Table 1, entries 1–5). Thus, the latter reaction conditions were used for the synthesis of 9-arylbenzo[b]quinolizinium derivatives 1b–d (Scheme 1, Table 1). The

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• , arenes and heteroarenes [43][44]. A first solution to value the 2-iodobenzoic moiety released from EBX has arisen from the reaction of derivatives 22 with N-(aryl)imines 23 in the presence of 10 mol % of Pd(OAc)2, which gives access to tri- or tetrasubstituted furans 24 and N-(aryl)formamides 25 (Scheme

• of Pd(OAc)2 in THF, and affords the dibenzoalkylidenefluorene 47 in an excellent 88% yield (Scheme 16). Ten years later, Huang, Wen and co-workers have demonstrated that, in the presence of both a terminal alkyne and a boronic acid, various cyclic diaryl-λ3-iodanes undergo a transition-metal

• be resubmitted to the cyclization conditions in the presence of a different terminal alkyne, or an activated alkene. The same authors have then showed that the reaction of cyclic diaryl-λ3-iodanes in the presence of internal alkynes and the catalytic system Pd(OAc)2-PCy3 affords functionalized

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