A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• be an effective catalyst for the synthesis of rhodamine and rosamine dyes as well as for their selenium or tellurium analogous [29], the usage of that Pd(0) catalyst showed yields comparable with those obtained with PdCl2(PPh3)2 (Table 1, entry 4). The exchange of sodium carbonate with cesium

• carbonate resulted in no reaction at all (Table 1, entry 5). Whereby usage of potassium phenyltrifluoroborate (19) resulted in a yield comparable to boroxine 18b (Table 1, entry 6), usage of pinacol ester 20 showed no reaction in the cross-coupling reaction (Table 1, entry 7). Although described

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• . Keywords: benzimidazole; cesium carbonate; cyclization; selenium; selenoazole; Introduction Selenium-containing heterocyclic ring systems have attracted attention not only because of their chemical properties and reactivities, but also for their wide biological activities [1][2][3][4]. For example

• . Experimental General procedure for the synthesis of benzoimidazo[2,1-b]benzoselenoazoles: 1-(2-Bromoaryl)benzimidazoles 1 (0.5 mmol), selenium powder (79 mg, 1.0 mmol, 2 equiv), and cesium carbonate (326 mg, 1.0 mmol, 2 equiv) were dissolved in DMF (1 mL) under Ar atmosphere. The mixture was stirred at 150 °C

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

• aromatic or aliphatic, only in case of triazoles substituted with an acetate group the final product was obtained in 66% yield. An open-flask, one-pot, Cu(II)-catalyzed ligand-free approach towards C–N bond formation was reported by Rasheed et al. [116]. The reaction was catalyzed by Cu(OAc)2 with cesium

• carbonate as a base under aerobic conditions. Along with the synthesis of pyrido[1,2-a]benzimidazoles 78, they have reported the synthesis of benzimidazo[1,2-a]quinoline 79 and benzimidazo[1,2-a]isoquinoline 80 in good to excellent yields. They have used differently substituted arylboronic acids 77 as one

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• tolerated, giving a comparable yield as the "standard conditions" (Table 1, entry 8). While changing the inorganic base to potassium phosphate tribasic or potassium carbonate gave yields below 75%, we found that cesium carbonate provided a net increase in the yield of the reaction (Table 1, entry 9

• procedure for the synthesis of aryl cyclopropyl sulfides A sealed tube equipped with a magnetic stirring bar was charged under ambiant air with cyclopropylboronic acid (25, 0.6 mmol, 1.5 equiv), cesium carbonate (0.4 mmol, 1.0 equiv), Cu(OAc)2 (0.4 mmol, 1.0 equiv), 2,2'-bipyridine (0.4 mmol, 1.0 equiv) and

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

• metal-free alternative to the previous methods of formation of sulfur heterocycles 70 has been reported by using elemental sulfur in the presence of cesium carbonate (Scheme 32) [72]. The strategy can be extended to the synthesis of the cyclic selenium analogs 71 by utilizing elemental selenium and

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• , 137.6, 132.23, 131.9, 127.6, 121.02 (q, J = 319.3 Hz); 19F NMR (470 MHz, MeOD) δ −80.60 (s); HRMS (TOF) m/z: [M − H]− calcd for C9H479BrF6N2O4S2−, 460.8706; found. 460.8766. 4-(1H-Benzo[d]imidazol-1-yl)-N-((trifluoromethyl)sulfonyl)benzamide (13): Cesium carbonate (163 mg, 5 equiv) was added to a glass

• closed screw cap vial to 100 °C for 1 min (color changed from yellow to deep red). A part of the catalyst mixture (0.2 mL) was added to a microwave glass vial containing a degassed mixture of 9d (33.1 mg, 0.1 mmol), 4-methoxyphenylboronic acid (22.8 mg, 0.15 mmol, 1.5 equiv) and cesium carbonate (100 mg

Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

• Shital Kumar Chattopadhyay,
• Suman Sil and
• Jyoti Prasad Mukherjee

Beilstein J. Org. Chem. 2017, 13, 2153–2156, doi:10.3762/bjoc.13.214

• an overall yield of 42% over five steps. One-pot deprotection–oxidation [14] of the oxazolidine moiety in 9 proceeded uneventfully to provide N-Boc-2-amino-6-heptenoic acid (10) in good yield. The latter was smothly protected as its methyl ester using methyl iodide in the presence of cesium carbonate

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• required functionalization of both amino groups present in 2-ABA was achieved by different routes involving selective N-acylation and cesium carbonate-mediated N-alkylation reactions, avoiding protection/deprotection steps. The heterocycles were efficiently synthesized in short reaction times by microwave

• , necessary for the synthesis of dihydroquinazolines 2, were prepared by N-alkylation of the arylamino group present in compounds 4 using alkyl halides. In a previous work [63], we developed a methodology for the selective N-alkylation of anilines with ω-halonitriles in the presence of cesium carbonate and

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

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• clear isosorbide-based polycarbonates were also reported by Shin and co-workers [86]. However, in this case, the polymerisation reaction was conducted using diphenyl carbonate in the presence of a catalytic amount of cesium carbonate. Another interesting isosorbide derivative is dimethyl isosorbide (DMI

Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• presence of cesium carbonate as base and N-methylpyrrolidone (NMP) as solvent [7][8]. Buchwald et al. [9] simplified the conditions by demonstrating that copper(I) iodide, potassium carbonate and the ligand N,N-dimethylethylenediamine can be used instead. Finally, Ma and co-workers [10] further modified

• the conditions using copper(I) iodide, cesium carbonate and N,N-dimethylglycine in 1,4-dioxane. Recently, Inoue applied this cross-coupling protocol to the synthesis of peptides (Scheme 2) [11][12] as demonstrated in the total synthesis of Yaku'amide A [13]. As part of our study on the total synthesis

• with cesium carbonate or potassium carbonate, the latter being superior to the former base, in 1,4-dioxane provided conditions that allowed us to prepare the coupling product 14 at room temperature. When raising the temperature to 50 °C the desired coupling product was isolated in 35% yield along with

Facile synthesis of 4H-chromene derivatives via base-mediated annulation of ortho-hydroxychalcones and 2-bromoallyl sulfones

• Srinivas Thadkapally,
• Athira C. Kunjachan and
• Rajeev S. Menon

Beilstein J. Org. Chem. 2016, 12, 16–21, doi:10.3762/bjoc.12.3

• Srinivas Thadkapally Athira C. Kunjachan Rajeev S. Menon Medicinal Chemistry and Pharmacology Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India 10.3762/bjoc.12.3 Abstract The cesium carbonate-mediated reaction of 2-bromoallyl sulfones and ortho-hydroxychalcones

• that such problems may be circumvented by developing a synthetic surrogate for the sensitive allenyl sulfones. Investigations along this direction led to the discovery that the easily prepared 2-bromoallyl sulfones 2a,b function as allenyl sulfone surrogates in the presence of cesium carbonate (Scheme

•  1, path a). Bromoallyl sulfones 2a,b partake in a cesium carbonate-mediated formal vinylic substitution reaction with heteronucleophiles to afford valuable multifunctional building blocks [23]. For example, the reaction of 2a with 4-chlorophenol afforded the enol ether 3 in 84% yield (Scheme 1, path

Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines with aryl iodides

• Svetlana P. Panchenko,
• Alexei D. Averin,
• Maksim V. Anokhin,
• Olga A. Maloshitskaya and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2015, 11, 2297–2305, doi:10.3762/bjoc.11.250

• ), EtCN or DMF were used as solvents and cesium carbonate (2.5 equiv) was taken as base (Scheme 1). The reactions were run under argon for ca. 24 h using 2.5 equiv of the aryl iodides with 0.5 M concentrations of polyamines. In the case of EtCN the reactions were refluxed (ca 100 °C), in the case of DMF

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• -pentyne and NaH in DMF to deliver compound 287. Then, indole-3-glyoxylate 288 was converted to N-alkylated derivative 289 by the treatment with 5-chloro-1-pentyne in the presence of cesium carbonate. The maleimide condensation of 287 and 289 was carried out in the presence of KOt-Bu at 0–23 °C to give the

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• phosphine, it is quite interesting and deserves mention. In the presence of cesium carbonate, chiral BIPHEP-derived phosphonium ylides reacted with various α,β-unsaturated aryl/alkylketones in THF at room temperature to afford corresponding cyclohexadienes in good yields and with up to 90% ee. It was

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

• gave no reaction. In the presence of copper(I) iodide and cesium carbonate diphenylphospine (25d) added to the triple bond in an anti-fashion. A diverse set of alkynylphosphines 139 was subjected to the protocol proving the compatibility of the method with certain functional groups. The Z-adducts were

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

• Christina Lohoelter,
• Malte Brutschy,
• Daniel Lubczyk and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2013, 9, 2821–2833, doi:10.3762/bjoc.9.317

• carried out (Scheme 4). Again, both paths A and B lead to the formation of the desired PNB protected diketone 11. Esterification was achieved by reaction with 4-nitrobenzyl chloride and cesium carbonate in DMF (Table 1, reaction conditions b for R = PNB) [68]. Both sequences A and B proceed with similar

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

• -catalyzed perfluoroalkylation of arenes in the absence of directing groups [70]. Perfluoroalkyl iodides were used as the source of the fluorinated alkyl group. Under the optimized reaction conditions, a mixture of the iodide, 5 mol % Pd2dba3, 20 mol % BINAP, cesium carbonate (2 equiv) and the arene (large

Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes

• Ana M. Sanjuán,
• Alberto Martínez,
• Patricia García-García,
• Manuel A. Fernández-Rodríguez and
• Roberto Sanz

Beilstein J. Org. Chem. 2013, 9, 2242–2249, doi:10.3762/bjoc.9.263

• the reaction of commercially available 2-methyl-1-propenylmagnesium bromide with 2-bromobenzyl bromide in the presence of CuI and 2,2’-bipyridyl [32]. This aryl bromide could be coupled with selected terminal alkynes by using cesium carbonate as a base and PdCl2(MeCN)2/XPhos as a catalytic system [33

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

• Marcia E. Richard,
• Daniel V. Fraccica,
• Kevin J. Garcia,
• Erica J. Miller,
• Rosa M. Ciccarelli,
• Erin C. Holahan,
• Victoria L. Resh,
• Aakash Shah,
• Peter M. Findeis and
• Robert A. Stockland Jr.

Beilstein J. Org. Chem. 2013, 9, 2002–2008, doi:10.3762/bjoc.9.235

• sieves. After filtration, they were dried under vacuum to afford white powders. Preparation of (IMes)Au(4-C6H4t-Bu) (4): General procedure A was followed with (IMes)AuCl (0.20 g, 0.37 mmol), 4-tert-butylphenylboronic acid (0.135 g, 0.76 mmol), cesium carbonate (0.24 g, 0.74 mmol), and isopropanol (1.5 mL

Enantioselective total synthesis of (R)-(−)-complanine

• Krystal A. D. Kamanos and
• Jonathan M. Withey

Beilstein J. Org. Chem. 2012, 8, 1695–1699, doi:10.3762/bjoc.8.192

• modification of the cesium carbonate-promoted coupling developed by Caruso and Spinella provided the most efficient conditions [4]. Thus, commercially available and unprotected 5-hexyn-1-ol underwent smooth coupling with 1-bromopent-2-yne in N,N-dimethylformamide, in the presence of stoichiometric amounts of

• cesium carbonate, copper iodide and tetrabutylammonium iodide. The resulting skipped diyne 2 was selectively reduced to homoconjugated all-Z-diene 1, with subsequent Swern oxidation affording aldehyde 3, in 86% yield from 2, as a key intermediate in the total synthesis. With 3 in hand, attention was then

N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters

• Takuya Uno,
• Yusuke Kobayashi and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2012, 8, 1499–1504, doi:10.3762/bjoc.8.169

• -pentafluorophenyl-substituted precatalyst 3e [45][46][47][48][49], whose C-2 proton is more acidic than 3d, furnished the coupled product 5a in good yield (Table 1, entry 5). Subsequently, we attempted several bases to find that cesium carbonate gave slightly lower yield (Table 1, entry 6), whereas an amine base

Synthesis of diverse indole libraries on polystyrene resin – Scope and limitations of an organometallic reaction on solid supports

• Kerstin Knepper,
• Sylvia Vanderheiden and
• Stefan Bräse

Beilstein J. Org. Chem. 2012, 8, 1191–1199, doi:10.3762/bjoc.8.132

• benzoic acids on Merrifield resin: In a three-necked round-bottom flask equipped with a mechanical stirrer, 5 equiv of cesium carbonate are suspended in DMF (mL/mmol) and are stirred for 30 min at 50 °C. Next, 5 equiv of benzoic acid are added and the mixture is stirred for another 30 min. Afterwards, one

Identification and synthesis of impurities formed during sertindole preparation

• I. V. Sunil Kumar,
• G. S. R. Anjaneyulu and
• V. Hima Bindu

Beilstein J. Org. Chem. 2011, 7, 29–33, doi:10.3762/bjoc.7.5

• -bromo-4-fluorobenzene (12), formation of traces of 5-chloro-1-(4-bromophenyl) indole (18) along with the desired indole 13 was observed. A detail study of this coupling reaction revealed significant formation of this undesired indole in the absence of a transition metal, especially when cesium carbonate

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups

• Julien Rolland,
• Xacobe C. Cambeiro,
• Carles Rodríguez-Escrich and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2009, 5, No. 56, doi:10.3762/bjoc.5.56

• stereospecific ring-opening with piperazine, and the resulting diamino alcohol 3 is subsequently supported onto a slightly cross-linked (1% DVB) Merrifield resin by direct treatment at room temperature in DMF in the presence of cesium carbonate (Scheme 3). Evaluation of resin 2 under batch conditions Prior to