Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin

• Markéta Bláhová,
• Sergey K. Filippov,
• Lubomír Kováčik,
• Jiří Horský,
• Simona Hybelbauerová,
• Zdenka Syrová,
• Tomáš Křížek and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248

• a cross-metathesis between previously described regioisomers of mono-O-allyl derivatives of γ-CD and 2-vinylnaphthalene which gives yields of about 16–25% (2–5% starting from γ-CD). To increase the overall yields, we have developed another method, based on a direct alkylation of γ-CD with 3

• supramolecular polymers [9] multifunctional molecules are assembled in a regular manner. To avoid branching, monosubstituted CDs are required for a linear supramolecular polymer of CDs with guest groups attached. Monosubstituted derivatives of CDs [10] include three regioisomers, namely 2I-O-, 3I-O-, and 6I-O

• -substituted ones. To separate pure regioisomers from their mixture is tricky. Their direct regioselective synthesis is possible, although not easy, because hydroxy groups at different positions of CD have different properties; the hydroxy group at position 6 is the most nucleophilic and basic one, the hydroxy

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• -amino ester stereo- and regioisomers, derived from unsaturated cyclic β-amino acids is described. The nucleophilic fluorinations involving hydroxy–fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate

• , cispentacin) are relevant antifungal agents [19]. Therefore we have selected some five and six-membered alicyclic dihydroxylated β-amino ester stereo- and regioisomers as model compounds [23][24][25][26], derived from cyclopentene or cyclohexene β-amino acids. These were used in order to evaluate their

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• it increases reaction rates and yields and directs the azide–alkyne cycloaddition exclusively towards 1,4-substituted regioisomers, whereas the non-catalyzed process results in a non-stoichiometric mixture of 1,4- and 1,5-regioisomers. Even though CuAAC reactions are efficiently performed in solution

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• it was found that the inclusion of the additive TMS-morpholine [36][37] was also required to ensure a high diastereoisomeric excess of 38a. The epoxide 38a was then ring-opened using Et3N·3HF to deliver the difluorodiol 39a as a mixture of regioisomers. This mixture subsequently converged during the

Curcuminoid–BF₂ complexes: Synthesis, fluorescence and optimization of BF₂ group cleavage

• Henning Weiss,
• Jeannine Reichel,
• Helmar Görls,
• Kilian Rolf Anton Schneider,
• Mathias Micheel,
• Michael Pröhl,
• Michael Gottschaldt,
• Benjamin Dietzek and
• Wolfgang Weigand

Beilstein J. Org. Chem. 2017, 13, 2264–2272, doi:10.3762/bjoc.13.223

• increasing electron density of the aromatic system, the emission intensity in the low-energy regime of the spectrum increases. It is also noteworthy, that regarding 2a and 2f, which are regioisomers, the second fluorescence band is more intense for 2f than for 2a. For the complexes containing a brominated

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• demonstrated that the reaction of highly electron-rich aromatics with nitrosoalkenes NSA14 affords the corresponding α-aryl-substituted oximes 66 in low to moderate yields as mixtures of regioisomers [44] (Scheme 22). Nitrosoalkenes were generated from the corresponding α-halooximes 65 upon treatment with

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

• latter transformation was a rhodium octanoate-catalyzed intramolecular carbenoid insertion into an ortho CAr–H bond (Scheme 1) [21][22], which proceeded with good yields in most cases. However, with non-equivalent aryl ortho-positions in the starting diazo compounds, mixtures of regioisomers – virtually

Accessing simply-substituted 4-hydroxytetrahydroisoquinolines via Pomeranz–Fritsch–Bobbitt reaction with non-activated and moderately-activated systems

• Marco Mottinelli,
• Mathew P. Leese and
• Barry V. L. Potter

Beilstein J. Org. Chem. 2017, 13, 1871–1878, doi:10.3762/bjoc.13.182

• - and the ortho-position to the substituent, as expected, the para-position predominated and the 7-substituted THIQs (e.g., 10e–g, Scheme 4) were obtained as the major product. Nevertheless, it was possible to isolate a usable amount of the 5-substituted THIQ 14e. The ratio of the two regioisomers

1-Imidoalkylphosphonium salts with modulated C_α–P⁺ bond strength: synthesis and application as new active α-imidoalkylating agents

• Jakub Adamek,
• Roman Mazurkiewicz,
• Anna Węgrzyk and
• Karol Erfurt

Beilstein J. Org. Chem. 2017, 13, 1446–1455, doi:10.3762/bjoc.13.142

•  3). The imidoalkylation of anisole and toluene gave the expected products as mixtures of ortho and para isomers in molar ratios ranging from 1.4:1.0 to 1.0:4.0 (Table 3). It seems that the steric congestion is the main factor governing the molar ratio of the regioisomers. Thus an excess of ortho

Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates

• Juraj Dobiaš,
• Marek Ondruš,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132

• acid) which we studied. Six regioisomeric 3,4-dihydroquinoxalin-2(1H)-one pairs were selectively prepared and characterised. Based on our experiences, a simplified methodology for determining the structure of the regioisomers was proposed. We developed two general and highly selective methodologies

• when choosing the most optimal reaction conditions for the synthesis of the desired 3,4-dihydroquinoxalin-2(1H)-one regioisomers with the best selectivity. The demonstrated methodologies in this article may also be applied to differently substituted 3,4-dihydroquinoxalin-2(1H)-ones in general, which

• monosubstituted o-phenylenediamines 11. In this case the amino groups usually have different reactivity and thus produce a mixture of regioisomeric products. If both regioisomers are needed, one can separate them [21]. Separation can be difficult to such an extent that some of the Cu(II) chelators were

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

• 10.3762/bjoc.13.126 Abstract Novel 13α-estrone derivatives were synthesized by Sonogashira coupling. Transformations of 2- or 4-iodo regioisomers of 13α-estrone and its 3-methyl ether were carried out under different conditions in a microwave reactor. The 2-iodo isomers were reacted with para-substituted

• compounds. All the halogenated 3-hydroxy and the 4-substituted regioisomers of 3-methyl ethers displayed substantial inhibitory activity against the 17β-hydroxysteroid dehydrogenase type 1 enzyme (17β-HSD1). Certain derivatives displayed a similar or more pronounced effect than those of their parent

• -catalyzed C–C coupling reactions. Some Sonogashira couplings on estrane, but not on the 13α-estrane core have been performed at C-2, -3, -11, -16 and -17. To the best of our knowledge, 4-coupled regioisomers have not been synthesized to date [19]. Couplings of steroidal alkynes with small molecular halides

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• min, 1,8-bis-carbothioamide 4, containing ≈20% of other regioisomers (9%) and nitrile 5 (7%) were isolated by column chromatography besides the expected 3o (78%). The amounts of 4 and 5 significantly increased along with the reaction time (Table 1). The highest yield of 4 (33%) was found after 6 h

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• , entry 7), chlorobenzene (2b + 2c, Table 2, entry 6 and 2q + 2r, entry 21), and toluene (2u + 2v, Table 2, entry 24). The exact structures of these regioisomers were determined on the basis of multiplet signals of the aromatic protons in the 1H NMR spectra. The observation of regioisomeric products

Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

• Gabriel P. Costa,
• Natália Seus,
• Juliano A. Roehrs,
• Raquel G. Jacob,
• Ricardo F. Schumacher,
• Thiago Barcellos,
• Rafael Luque and
• Diego Alves

Beilstein J. Org. Chem. 2017, 13, 694–702, doi:10.3762/bjoc.13.68

• as a mixture of regioisomers (6:1) (Table 2, entry 10). In addition, the possibility to perform the reaction of 2-azidophenyl phenyl selenide (1a) with β-keto-esters, β-keto-amides and α-cyano-ketones 2f–k was also investigated. The reaction conditions optimized for 1,3-diketone 2a were employed, but

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• the yields of isoxazole products are quite low because of side reactions and both regioisomers are generally obtained [23][24][25]. The one-pot 1,3-dipolar cycloaddition reaction of a nitrile oxide, generated in situ from the corresponding hydroxymoyl chloride, with an in situ brominated electron

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• ] cyclotrimerization of the dialkyne 306 with variously disubstituted alkynes 307 performed on a solid phase TentaGel® resin (0.25 mmol/g) in the presence of Ru catalyst (Scheme 86). In case of 309–316, this reaction led to the formation of mixtures of two regioisomers. The examined regioisomeric ratios (a/b) were

• ranged from 1:2 to 2:3 with a preference to 310a–315a regioisomers. An interesting approach to the synthesis of 1-indanones and 1-indenones is based on the hexadehydro-Diels–Alder (HDDA) reaction in which an alkyne reacts in the [4 + 2] cycloaddition with diyne and forms a reactive benzyne species as a

Brønsted acid-mediated cyclization–dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines

• Ramana Sreenivasa Rao and
• Chinnasamy Ramaraj Ramanathan

Beilstein J. Org. Chem. 2017, 13, 428–440, doi:10.3762/bjoc.13.46

• phenyl group was proposed to introduce at the 3-position in substituted pyrazinone via regioselective bromination followed by Suzuki coupling with phenylboronic acid. Accordingly, the bromination of 10a was successfully carried out to furnish regioisomers 12a and 12b in 82% yield upon treatment with

• bromodimethylsulfonium bromide (BDMS) [38] in dichloromethane at 0 °C to room temperature. The conventional Suzuki coupling of the regioisomers 12a and 12b with phenylboronic acid furnished the corresponding arylated products 13a and 13b in excellent yield (Scheme 5). To our dismay, the imide 7h did not participate in

• reaction mixture was purified through silica gel column chromatography using ethyl acetate/hexane, 30:70 as eluent to afford 12a and 12b in the ratio 79:21. The regioisomers of bromopyrazinone (12a and 12b) (1.0 mmol), bis(triphenylphosphine)palladium(II) chloride (10 mol %, 7 mg) in dimethylformamide (2

Revaluation of biomass-derived furfuryl alcohol derivatives for the synthesis of carbocyclic nucleoside phosphonate analogues

• Bemba Sidi Mohamed,
• Christian Périgaud and
• Christophe Mathé

Beilstein J. Org. Chem. 2017, 13, 251–256, doi:10.3762/bjoc.13.28

• treatment with Boc2O afforded the suitable heterocyclic precursor 17 (Scheme 4). The coupling reaction of (+/−)-7 and 17 using the Mitsunobu reaction gave a separable mixture of N9/N7 regioisomers (+/−)-18 and (+/−)-19 with 55% and 5% yield, respectively. After purification, compound (+/−)-18 was treated

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• exclusively at the equatorial 4-OH group presumably due to the bulkiness of the silylated donor. Thus compound 55 (Scheme 9) was formed as the only product out of four possible isomers in 54% yield. When the D-gluco-configured acceptor analogue of 54 was used, a mixture of regioisomers was obtained. However

Multicomponent synthesis of spiropyrrolidine analogues derived from vinylindole/indazole by a 1,3-dipolar cycloaddition reaction

• Manjunatha Narayanarao,
• Lokesh Koodlur,
• Vijayakumar G. Revanasiddappa,
• Subramanya Gopal and
• Susmita Kamila

Beilstein J. Org. Chem. 2016, 12, 2893–2897, doi:10.3762/bjoc.12.288

• -alkylindole and indazole derivatives 2 that can be obtained from 5-bromoindoles/indazoles (1). The latter compounds were synthesized according to procedures described in the literature [18][19][20]. The regioisomers of N-alkylated 5-bromoindazoles were isolated by column chromatography using a hexane–ethyl

• indazole analogues 7e–k under similar reaction conditions. Based on the same logic of vinylindole, regioisomers of N-alkylvinylindazole were considered. So, this 1,3-dipolar cycloaddition reaction could be well applied to both derivatives which afforded a range of differentially substituted final products

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• –n leading to (±)-5b–n. Reaction conditions: (±)-6b–h (0.4 mmol), TsOH·H2O (20 mol %), toluene (8 mL), 80 °C, 45 min. The numbers in parentheses represent isolated yields after silica gel column chromatography. aYield of isolated mixture of the inseparable regioisomers. ORTEP diagram of 5k

Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

• Vladimir A. Stepchenko,
• Anatoly I. Miroshnikov,
• Frank Seela and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2016, 12, 2588–2601, doi:10.3762/bjoc.12.254

• -thiouridine (very weak substrate) vs uridine (non-substrate), thymidine (very weak substrate) vs 2-thiothymidine (non-substrate). Shugar and co-workers studied the substrate properties of N-3-regioisomers of adenosine and inosine, N3-(β-D-ribofuranosyl)-adenine (N3-Ado) and -hypoxanthine (N3-Ino

• the PNPs. Noteworthy that phosphorolysis of both N-3-regioisomers proceeds irreversibly. In the present work, we compared the energy minimized structures of N3-Ado and 5-aza-2'-deoxycytidine (14) and found a rather similar stereochemistry of both structures, in particular, a quite similar orientation

Facile synthesis of a 3-deazaadenosine phosphoramidite for RNA solid-phase synthesis

• Elisabeth Mairhofer,
• Elisabeth Fuchs and
• Ronald Micura

Beilstein J. Org. Chem. 2016, 12, 2556–2562, doi:10.3762/bjoc.12.250

• through celite and partitioned between dichloromethane and 5% aqueous sodium bicarbonate solution (10 mL each). The organic layer was washed twice with 5% aqueous sodium bicarbonate solution (2 × 10 mL), dried over Na2SO4 and evaporated. The regioisomers were separated by flash chromatography (toluene

Biomimetic synthesis and HPLC–ECD analysis of the isomers of dracocephins A and B

• Viktor Ilkei,
• András Spaits,
• Anita Prechl,
• Áron Szigetvári,
• Zoltán Béni,
• Miklós Dékány,
• Csaba Szántay Jr,
• Judit Müller,
• Árpád Könczöl,
• Ádám Szappanos,
• Attila Mándi,
• Sándor Antus,
• Ana Martins,
• Attila Hunyadi,
• György Tibor Balogh,
• György Kalaus (†),
• Hedvig Bölcskei,
• László Hazai and
• Tibor Kurtán

Beilstein J. Org. Chem. 2016, 12, 2523–2534, doi:10.3762/bjoc.12.247

• by preparative HPLC to result in regioisomers (±)-2a–d and (±)-3a–d as crystalline powders in a ratio of 43:57, respectively. These data clearly showed that the reaction took place without notable regioselectivity, which was in agreement with the observed 58:42 ratio of natural dracocephins A and B

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

• Ilya V. Efimov,
• Marsel Z. Shafikov,
• Nikolai A. Beliaev,
• Natalia N. Volkova,
• Tetyana V. Beryozkina,
• Wim Dehaen,
• Zhijin Fan,
• Viktoria V. Grishko,
• Gert Lubec,
• Pavel A. Slepukhin and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

• challenge. We turned our attention to the reaction of enamines with nitrile oxides (or their precursors, hydroxamoyl chlorides). The reaction has been shown to take place regioselectively to form only one of two possible regioisomers [18][19][20][21][22][23][24][25][26]. Therefore, this holds some promise

• around the double bond, and found to be 38.09 kcal∙mol−1 above 1a_1 in free energy. Calculations of the suggested mechanisms (Scheme 3) performed for E-isomer 1a_1 and nitrile oxide 6a allowed localizing a concerted transition state for both, observed and not observed regioisomers 3 and 8, respectively