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

Rapid regio- and multi-coupling reactivity of 2,3-dibromobenzofurans with atom-economic triarylbismuths under palladium catalysis

• Maddali L. N. Rao,
• Jalindar B. Talode and
• Venneti N. Murty

Beilstein J. Org. Chem. 2016, 12, 2065–2076, doi:10.3762/bjoc.12.195

• trial reaction was performed with 2,3-dibromobenzofuran (1.1, 3.3 equiv) and tri(p-anisyl)bismuth (1 equiv) with Pd(OAc)2/PPh3, Cs2CO3 (3 equiv) in N-methyl-2-pyrrolidone (NMP) at 90 °C for 1 h as protocol conditions [35]. This protocol furnished the preferential cross-coupling at the more electrophilic

• could be obtained in excellent yield with Pd(OAc)2/4 PPh3 (0.1 equiv) Cs2CO3 (4 equiv) in NMP at 90 °C and 2 h reaction time (Table 1, entry 3) and it was considered as optimized protocol for our further study. To check the generality of this regio-selective coupling, various 2,3-dibromobenzofurans have

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

• fixed 5 mol % of Pd(OAc)2 and 10 mol % of the phosphine ligand was investigated. It was noted that the catalyst level could be reduced [34], but this amount allowed for an efficient catalytic process with short reaction times in the region of two hours, a good match for the flow system assembly [8

Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

• Shulei Pan,
• Hang Jiang,
• Yanghui Zhang,
• Yu Zhang and
• Dushen Chen

Beilstein J. Org. Chem. 2016, 12, 1302–1308, doi:10.3762/bjoc.12.122

• tetraphenylene (1). For this, 1 was allowed to react with PhI(OAc)2 (2a) in the presence of Pd(OAc)2/pyridine as catalysis system in a mixture of AcOH and Ac2O at 100 °C. Gratefully, the desired acetylated product 3a was formed in 52% yield (Table 1, entry 1). Prolonging the reaction time or carrying out the

• promote the reaction. Therefore, we screened the effect of different co-solvents on the reaction and dichloromethane was found to be the best choice (Table 5, entries 4 and 5). The yield was remarkably improved by increasing the amount of Pd(OAc)2 (Table 5, entry 6). Raising or lowering the temperature

• methods for the synthesis of a variety of 2-substituted tetraphenylenes, which could accelerate the research on the properties and application of tetraphenylene derivatives. Tetraphenylene and its saddle-shaped structure. The Pd(OAc)2-catalyzed reaction of nitriles with tetraphenylene (1). The Pd(OA)2

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• one-pot reaction of carbodiimide 197, isocyanide 199 and dialkyl phosphonates 198 under optimized conditions (10 mol % of Pd(OAc)2, 10 mol % of FeCl3, 10 mol % of DPPF, 3.0 equiv of Cs2CO3, toluene, reflux) led to (4-imino-3,4-dihydroquinazolin-2-yl)phosphonates 203 in 37–78% yields (Scheme 42). This

Palladium-catalyzed picolinamide-directed iodination of remote ortho-C−H bonds of arenes: Synthesis of tetrahydroquinolines

• William A. Nack,
• Xinmou Wang,
• Bo Wang,
• Gang He and
• Gong Chen

Beilstein J. Org. Chem. 2016, 12, 1243–1249, doi:10.3762/bjoc.12.119

• diverse substitution patterns from readily accessible starting materials. New synthetic strategy for THQs via PA-directed C−H functionalization. Preparation of iodo-substituted THQs via PA-directed C−H functionalization strategy. a) ArI (2 equiv), Pd(OAc)2 (10 mol %), (BnO)2PO2H (20 mol %), Ag2CO3 (1.5

• equiv), t-AmylOH, 110 °C, 24h; b) Pd(OAc)2 (10 mol %), I2 (4 equiv), PhI(OAc)2 (4 equiv), KHCO3 (1 equiv), 130 °C, DMF, 24 h; c) NIS (1.1 equiv), HBF4.OEt2 (4), TFA/DCM (1:9), 2.5 mM, 0 °C, 4 h; d) CuI (10 mol %), CsOAc (2.5 equiv), DMSO, Ar, 90 °C, 20 h; e) NIS (1.1 equiv), TFA/DCM (1:9), 2.5 mM, rt

• , 16 h; f) Pd(OAc)2 (15 mol %), NIS (2.5 equiv), α,α,α-trifluorotoluene, Ar, 100 °C, 24 h. Removal of PA auxiliary from THQ product. Optimization of Pd-catalyzed ortho C−H iodination of 5.a Substrate scope of Pd-catalyzed ε-C−H iodination and Cu-catalyzed C−N cyclization to form THQsa. Supporting

Synthesis of β-arylated alkylamides via Pd-catalyzed one-pot installation of a directing group and C(sp³)–H arylation

• Yunyun Liu,
• Yi Zhang,
• Xiaoji Cao and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2016, 12, 1122–1126, doi:10.3762/bjoc.12.108

• a model reaction. The primary reaction in the presence of Pd(OAc)2 provided smoothly the target product 4a (entry 1, Table 1). The variation in the effect of catalyst loading proved that 5 mol % was proper (entries 2 and 3, Table 1). Further investigations using different palladium catalysts such as

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

• 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

• . Although the combination of acetanilide together with a palladium(II) catalyst lead to the corresponding palladacycle, as reported by Tremont [172], in the presence of 2a, Pd(OAc)2, HBF4 and AgOAc at room temperature, acetyl or isopropyl anilides afford essentially no product. Only after heating to 50 °C

• were examined, such as Pd(OAc)2, PdCl2Ln, Pd2(dba)3, in the absence of added acid, but none led to cross-coupling at room temperature. 1,4-Benzoquinone (BQ) was found to be an effective additive in promoting the reaction, while addition of stoichiometric metal salts (e.g., silver or copper salts) was

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• . The screening was then continued with Pd(OAc)2 and tri-(o-tolyl)phosphine (P(o-tol)3) used as a catalyst in the mixture toluene/water/ethanol as solvent system and with sodium carbonate as a base. In order to control the progress of the process, the mixture was regularly sampled and the components

• leading to a more active monophosphine Pd complex. In our case, tricyclohexylphosphine associated with Pd(OAc)2 in toluene/H2O/EtOH confirmed its utility as a powerful catalytic system, giving fast and clean conversion of substrate 1 within 2–3 hours. When the reaction was performed with 2.8 equiv of

• phenylboronic acid in the presence of Pd(OAc)2/P(Cy)3, the final diarylpyridine 4 was obtained in each case in very good yield (95–99%, Table 1, entries 21–26) and the outcome of the reaction was independent on the base and the solvent used. The only exception was entry 27, where CsF as a mild base was applied

N-Methylphthalimide-substituted benzimidazolium salts and PEPPSI Pd–NHC complexes: synthesis, characterization and catalytic activity in carbon–carbon bond-forming reactions

• Senem Akkoç,
• Yetkin Gök,
• İlhan Özer İlhan and
• Veysel Kayser

Beilstein J. Org. Chem. 2016, 12, 81–88, doi:10.3762/bjoc.12.9

• same product in much higher yields such as 90 and 93% under reaction conditions of 1 mol % of Pd(OAc)2, 1 mol % of 1 and 2, KOH, DMF/H2O within a short period of time (1 h) at 80 °C. The synthesized carbene precursors consist of an electron-neutral group (benzyl), electron-donating group (3

• –NHC complex as catalyst resulted in low yields and conversions (Table 3, entries 9–12). The usage of the morpholinoethyl substituted benzimidazolium compound 4 with Pd(OAc)2 resulted in higher yields of 2-(4-nitrophenyl)benzo[b]thiophene compared to the usage of compounds 1–3. Generally, the PEPPSI Pd

Selectively fluorinated cyclohexane building blocks: Derivatives of carbonylated all-cis-3-phenyl-1,2,4,5-tetrafluorocyclohexane

• Mohammed Salah Ayoup,
• David B. Cordes,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2015, 11, 2671–2676, doi:10.3762/bjoc.11.287

• an electrostatically positive (δ +ve) hydrogen face. X-ray structure of aldehyde 15. CCDC number 1432193. Preparation of benzoic acids 11–13; i. HIO4·2H2O (50%), AcOH, H2SO4, I2, H2O, 70 °C 24 h, 92%.; ii. Pd(OAc)2, Ph3P,Et3N, EtOH, CO (1 atm), 80 °C, 16 h. iii. HCl (6 M), 1,4-dioxane, 70 °C, 24 h or

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• [26][27], indeed when 10 was treated with a substoichiometric amount of Pd(OAc)2 in DMSO at 58 °C under an oxygen atmosphere, it was possible to isolate 11 ([α]D +11.1° (c 1.4, CHCl3), vs lit. [13] [α]D +9.7° (c 0.14, EtOH)) in a maximum yield of 54%, as no starting material was present anymore in the

• reaction mixture. Very recently, Stahl et al. have proved that by replacing Pd(OAc)2 with Pd(TFA)2 it is possible to dehydrogenate directly the ketones at room temperature [28], but without the possibility of controlling the regioselectivity. Since, in our case this issue is critical we tried to apply the

• dehydrogenations (mainly DMSO or MeCN); even when using mixed co-solvent systems, the results were still very poor. Next, we tested the Tsuji variant [30] (Pd(OAc)2, dppe, diallyl carbonate, MeCN) but both 10 and 10a decomposed during the reaction. Finally, (+)-hernandulcin 1 was obtained in a 92% yield by

Efficient synthesis of π-conjugated molecules incorporating fluorinated phenylene units through palladium-catalyzed iterative C(sp²)–H bond arylations

• Fatiha Abdelmalek,
• Fazia Derridj,
• Safia Djebbar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2015, 11, 2012–2020, doi:10.3762/bjoc.11.218

• of heteroarylated polyfluorobiphenyls in good yields via two or three sequential iterative palladium-catalyzed direct arylations. Different pathways for the synthesis of π-conjugated molecules incorporating fluorinated phenylene units. i) Pd(OAc)2, KOAc, DMA, 150 °C. ii) PdCl(C3H5)(dppb), KOAc, DMA

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• aryldiazonium tetrafluoroborates with NHC-Pd catalysts was reported recently [63]. When applied to 3a and 3b using Pd(OAc)2 and NHC ligand precursors L, the borylated products 2a and 2b were isolated in only moderate yields (Table 2, entries 1 and 2). However, it was found that the Pd catalyst was not required

• potassium SF5-phenyltrifluoroborates were found to be highly reactive with a variety of aryl bromides and iodides in the presence of catalytic amounts of PdCl2(dppf)·CH2Cl2 or Pd(OAc)2 [72]. The recently published synthesis of arylboronic acids from anilines or aryldiazonium tetrafluoroborates using B2(OH)4

Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• .11.146 Abstract An intramolecular dehydrogenative C–H activation enabled an efficient synthesis of an uracil-annulated β-carbolinone ring system. The reaction is simple, efficient and high yielding (85–92%). Keywords: β-carbolinones; cyclization; dehydrogenative C–H activation; Pd(OAc)2; uracil

• base. The amide precursor was then subjected to a series of reactions in pursuit of the best reaction conditions for the dehydrogenative cross-coupling process. Assuming that the reaction goes through an electrophilic metallation pathway, it was projected that Pd(OAc)2 would be an excellent starting

• point for catalyst screening. The amide 4a (R1 = R2 = R3 = R4 = Me) was used as a model substrate for this dehydrogenative coupling reaction. The reaction was set up in the presence of Pd(OAc)2 (10 mol %), Cu(OAc)2 (2 equiv) in DMF under open air at 70 °C (Table 1, entry 1). After 8 h we obtained 35