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

• (PMB) from the nitrogen, the methyl 1-(4-methoxybenzyl)-1,3-dihydrobenzo[c]isothiazole-3-carboxylate-2,2-dioxide (10a) was treated with cerium(IV) ammonium nitrate (CAN) according to a previously developed protocol [18][20]. Unexpectedly, this PMB resisted its removal, and the only formed product was

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• of conversion could be similar to the one depicted in Scheme 3. In another example anhydrous cerium chloride was used as a co-catalyst to activate IBX towards oxidative dehydrogenation of various heterocycles such as 1-substituted tetrahydroisoquinolines 18, tetrahydro-β-carbolines 19 and

• benzothiazolidines 20 to their corresponding heterocyclic analogs 21–24 at room temperature [36]. Anhydrous cerium chloride is believed to coordinate with IBX to increase the electrophilicity of the iodine center and thereby generating F, where the coordination of the amine substrate becomes much more facile thereby

• dehydrogenation of N-heterocycles [31][32][33][34]. IBX-mediated room temperature one-pot condensation–oxidative dehydrogenation of o-aminobenzylamines. Anhydrous cerium chloride-catalyzed, IBX-mediated oxidative dehydrogenation of various heterocycles at room temperature. Oxidative dehydrogenation of

Grip on complexity in chemical reaction networks

• Albert S. Y. Wong and
• Wilhelm T. S. Huck

Beilstein J. Org. Chem. 2017, 13, 1486–1497, doi:10.3762/bjoc.13.147

• the BZ network comprises five reactions that can be translated into three inorganic processes in acidic conditions: (1) autocatalytic production of HOBr2 (X) in the presence of Br− (Y), (2) oxidation of the cerium catalyst, Ce3+ → Ce4+ (Z), and (3) the regeneration of Br− and Ce3+ fueled by the

Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions

• Manuel Anselmo,
• Lisa Moni,
• Hossny Ismail,
• Davide Comoretto,
• Renata Riva and
• Andrea Basso

Beilstein J. Org. Chem. 2017, 13, 1456–1462, doi:10.3762/bjoc.13.143

• %) without any other detectable product. However, the TLC analysis of the crude material, after staining with cerium molybdate, displayed a plethora of red-colored spots typical for 4-methoxybenzyloxycarbonyl (MeOZ) cleavage with trifluoroacetic acid, thus suggesting the formation of a 4-methoxybenzyl

Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives

• Roman A. Irgashev,
• Nikita A. Kazin,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136

• many cases 3,6-unsubstituted carbazoles have been nitrated by using fuming or 70% nitric acid with or without addition of acetic anhydride [46]. Two inorganic nitrates, such as copper(II) nitrate [47] or cerium(IV) ammonium nitrate (CAN) [48] have also been used to give 3-mononitro or 3,6-dinitro

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• either using the Lindlar catalyst (84.6%) under smooth reaction conditions (298 K, 1 bar H2, Table 1, entry 1) or 16.2 wt % CeO2@TiO2 (97%), the latter resulting in a very high STY for 1a (18.86 kg L−1 h−1) under solvent-free conditions (Table 1, entry 2) [119]. Use of cerium oxide is certainly

First DMAP-mediated direct conversion of Morita–Baylis–Hillman alcohols into γ-ketoallylphosphonates: Synthesis of γ-aminoallylphosphonates

• Marwa Ayadi,
• Haitham Elleuch,
• Emmanuel Vrancken and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2906–2915, doi:10.3762/bjoc.12.290

• mixture of Ac2O and DMAP as reagents (Scheme 7). The MBH acetate 7 was further converted into the γ-aminophosphonates 8a–c within short reactions times of 1–2 h and in 60–81% isolated yields using anilines, and 1 equiv of cerium(III) chloride hexahydrate in refluxing toluene (Table 5, entries 1–3). The

Total synthesis of leopolic acid A, a natural 2,3-pyrrolidinedione with antimicrobial activity

• Atul A. Dhavan,
• Rahul D. Kaduskar,
• Loana Musso,
• Leonardo Scaglioni,
• Piera Anna Martino and
• Sabrina Dallavalle

Beilstein J. Org. Chem. 2016, 12, 1624–1628, doi:10.3762/bjoc.12.159

• cleavage with cerium ammonium nitrate (CAN) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). Thus, 2,3-pyrrolidinedione 3 was obtained by the reaction of ethyl acrylate with p-methoxybenzylamine, followed by treatment with diethyl oxalate (Scheme 1) [12]. On the basis of NMR data, the compound exists as an

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• sufficiently activated for the last ketone–ketone–aldol step. For lanthanum and cerium and maybe even for tin(II) the size may cause problems since these ions are too big. The distance between the reactants is probably too large for a bond formation (Table 9). In the case of 9-anthracenylaldehyde (3f

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• aldehyde 67 in six steps in 34% yield. After saponification of the ester functionality, treatment with tosyl chloride and trimethylamine resulted in the formation of a ketene that underwent a diastereoselective intramolecular [2 + 2] cycloaddition to provide bicyclic ketone 69. Addition of TMS cerium

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

• subjected to cerium ammonium nitrate for oxidative demethylation and the amino quinone formed cyclized to afford neoamphimedine (12, Scheme 4) [62]. Two synthetic routes, illustrated in Scheme 2 and Scheme 3, were used to prepare neoamphimedine (12) where the second description was shorter and more

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

• intramolecular benzannulation reaction in the presence of a polar solvent such as THF to deliver [6,6]metacyclophane (321a, 25%, 321b, 20% and 321c, 38%). Similarly metabenzoquinonophane 322 has been synthesized starting with 320 by an in situ oxidation of the benzannulated product by using cerium(IV) ammonium

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• the presence of oxidants based on manganese, cobalt, and cerium [197]. The best results were achieved with the use of Mn(OAc)3 and the Co(OAc)2(cat)/KMnO4 system (Scheme 43). The yields of products 206 were as high as 94%. It is supposed that the oxidant serves two functions: the generation of N-oxyl

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• phenylthio-substituted 1,2-oxazine derivatives [32]. Compound 10 is easily accessible by a mild cleavage of the corresponding acetonide by an indium trichloride-mediated hydrolysis [33]. By using cerium ammonium nitrate as Lewis acid [34] in high concentration (13 mmol/mL) as well as an excess of 1-bromo-4

Synthesis of zearalenone-16-β,D-glucoside and zearalenone-16-sulfate: A tale of protecting resorcylic acid lactones for regiocontrolled conjugation

• Hannes Mikula,
• Julia Weber,
• Dennis Svatunek,
• Philipp Skrinjar,
• Gerhard Adam,
• Rudolf Krska,
• Christian Hametner and
• Johannes Fröhlich

Beilstein J. Org. Chem. 2014, 10, 1129–1134, doi:10.3762/bjoc.10.112

• cleavage using cerium ammonium nitrate (CAN) did not lead to the formation of the deprotected compound 20 (Scheme 5). Beside unreacted 19, LC–MS/MS analysis showed the formation of a product with an m/z value 16 amu higher than calculated for 19 indicating oxidation of this intermediate but no deprotection

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• envisaged to be constructed by 1,2-addition, using the free β-hydroxy functionality in 63 as directing group. Several conditions with allyl boronates, stannanes, silanes, indium, magnesium bromide, cerium, zinc bromide and other reagents have been screened. Finally, the best result was achieved with

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• -dioxanes Modern approaches to the synthesis of 1,2-dioxanes are based on reactions with singlet oxygen, the oxidative coupling of carbonyl compounds and alkenes in the presence of manganese and cerium salts, the co-oxidation of alkenes and thiols with oxygen, the Isayama–Mukaiyama peroxidation, the

• -dioxan-3-ol (202) and 6-(prop-1-en-2-yl)-1,2-dioxane-3-imine (204), containing the hydroxy and imine groups, respectively (Scheme 56) [304]. 3.2. Oxidative coupling of carbonyl compounds and alkenes in the presence of manganese or cerium salts The synthesis of 1,2-dioxanes 207 is based on the addition of

• alkene 205 and oxygen to carbonyl compound 206 via the intermediate formation of carbon-centered peroxide radicals. The reaction occurs in the presence of catalytic amounts of manganese or cerium salts, which are involved in a redox cycle. It is assumed that the oxidation of β-dicarbonyl compounds

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

• Jie Zhang,
• Hong-Kui Zhang and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2013, 9, 2358–2366, doi:10.3762/bjoc.9.271

• previous assumption outlined in Scheme 4. To remove the PMB protecting group, compound 11 was treated with ammonium cerium nitrate (CAN) in CH3CN/H2O (v/v 3:1) [50] at room temperature for 4 h to afford the deprotected lactam 22 in 56% yield. Our next task was the oxidative cyclization of the olefin 22 to

• added ammonium cerium nitrate (2.5 g, 4.56 mmol) in one portion. The mixture was stirred for 4 h at room temperature. To the resulting mixture was added H2O (5 mL), and the mixture was extracted with EtOAc (30 mL × 5). The combined organic layers were washed successively with a saturated solution

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• derivatives are treated with α,β-unsaturated carbonyl compounds in the presence of ammonia to initially form dihydropyridines 1.38, which can ultimately be converted into the corresponding aromatic pyridine upon oxidation with a variety of oxidants such as MnO2, HNO2, HNO3 or cerium ammonium nitrate (CAN

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• experiments where NO3• was used in the absence of other radical and non-radical oxidants, NO3• was generated at room temperature from cerium(IV) ammonium nitrate (CAN) through photo-induced electron transfer at an irradiation wavelength of λ = 350 nm (Scheme 1b) [11][12][13]. In a typical experiment, the

Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds

• Brian M. Casey,
• Dhandapani V. Sadasivam and
• Robert A. Flowers II

Beilstein J. Org. Chem. 2013, 9, 1472–1479, doi:10.3762/bjoc.9.167

• -electron oxidations employing δ-aryl-β-dicarbonyl compounds have been carried out on arenes containing pendant β-ketoesters [10][11]. When Mn(III)-based oxidants are employed, secondary oxidations of the 2-tetralone products can occur [10][11]. Cerium(IV) ammonium nitrate (CAN) is a versatile, inexpensive

An efficient access to the synthesis of novel 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives

• Wentao Gao,
• Guihai Lin,
• Yang Li,
• Xiyue Tao,
• Rui Liu and
• Lianjie Sun

Beilstein J. Org. Chem. 2012, 8, 1849–1857, doi:10.3762/bjoc.8.213

• -aminobenzophenone (1) with 4-chloroethylacetoacetate by using CAN (cerium ammonium nitrate, 10 mol %) as catalyst at room temperature. The substrates 3a–l were prepared through one-pot reaction of ethyl 2-(chloromethyl)-4-phenylquinoline-3-carboxylate (2) and substituted phenols. Our developed strategy, involving a

Asymmetric total synthesis of smyrindiol employing an organocatalytic aldol key step

• Dieter Enders,
• Jeanne Fronert,
• Tom Bisschops and
• Florian Boeck

Beilstein J. Org. Chem. 2012, 8, 1112–1117, doi:10.3762/bjoc.8.123

• introduction of the methyl group by using the Imamoto protocol [13] employing cerium(III) chloride and methyllithium at −78 °C, was unreliable with highly varying yields of the 1,3-diol. This irreproducibility is probably due to the heterogeneous nature of the reaction mixture. Fortunately, the use of

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• chromatography was performed on TLC plates Si 60 F254 (Merck) in petroleum ether (PE), ethyl acetate (EE) or other solvents as indicated, and compounds were visualized under UV and after spraying with a cerium-molybdate spray reagent (20 g ammonium molybdate, 0.4 g cerium(IV) sulfate in 400 mL 10% sulfuric acid

Efficient synthesis of 1,3-diaryl-4-halo-1H-pyrazoles from 3-arylsydnones and 2-aryl-1,1-dihalo-1-alkenes

• Yiwen Yang,
• Chunxiang Kuang,
• Hui Jin,
• Qing Yang and
• Zhongkui Zhang

Beilstein J. Org. Chem. 2011, 7, 1656–1662, doi:10.3762/bjoc.7.195

• important intermediates that can easily be converted into 1,2,4-triaryl- or 1,2,5-triaryl-substituted pyrazoles. In addition, 1-(4-methoxyphenyl)-1H-pyrazoles (such as compounds 3g, 3h and 3i) are also important intermediates, as they can react with cerium(IV) ammonium nitrate (CAN), leading to N