Investigation of the action of poly(ADP-ribose)-synthesising enzymes on NAD⁺ analogues

• Sarah Wallrodt,
• Edward L. Simpson and
• Andreas Marx

Beilstein J. Org. Chem. 2017, 13, 495–501, doi:10.3762/bjoc.13.49

• acceptors forming mono- or poly(ADP-ribos)ylated proteins. Out of the 18 members identified, only four are known to synthesise the complex poly(ADP-ribose) biopolymer. The investigation of this posttranslational modification is important due to its involvement in cancer and other diseases. Lately, metabolic

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

• papilloma virus type 11 (HPV11) inhibitors. These 1-indanones 99 have been synthesized using a N-heterocyclic carbene-catalyzed [4 + 1] annulation utilizing phthalaldehyde (97) and 1,2-diactivated Michael acceptors 98 (Scheme 31) [55][56]. 1.1.5 From ketones and 1,2-diketones: Another interesting approach

A postsynthetically 2’-“clickable” uridine with arabino configuration and its application for fluorescent labeling and imaging of DNA

• Heidi-Kristin Walter,
• Bettina Olshausen,
• Ute Schepers and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2017, 13, 127–137, doi:10.3762/bjoc.13.16

• the dyes into the major groove led them find a better orientation than in the minor groove, with respect to the DNA helix with enhanced fluorescence intensities. The dyes D1–D4 as energy donors were combined with dyes D5–D9 as energy acceptors (Scheme 3). This approach follows our concept of “DNA/RNA

• absorption of the acceptors show broad spectral overlays and therefore selective excitation is not possible. For each of the previously described dye combinations, we probed all four combinations of arabino- and ribo-configured donor strands (DNA2a and DNA2r) with acceptor strands (DNA3a and DNA3r). This

• /lysosomal vesicles. The fluorescence of the energy donors, D1, D2 and D4 (Figure 2, left column), as well as the fluorescence of the energy acceptors, D5 and D8 (Figure 2, middle column), could be detected showing that fluorescence energy was transferred from the donor to the acceptor in the respective FRET

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

• acceptors. However, glycosylation with heavily silylated carbohydrate derivatives is comparatively new, and so is the significance that silyl groups have on the stereoselectivity and reactivity in glycosylation reactions [4]. These findings, which most have occurred in the last decade, will be reviewed here

• reactivity of the corresponding glycosyl donors. The increased reactivity is very clearly displayed when TBS or TIPS-protected thioglycosyl donors are mixed with benzylated thioglycoside acceptors under activating conditions (Table 1). The benzylated thioglycosides 21 and 26, normally termed ‘armed’ due to

• thioglucoside 45 was found to be much less reactive than 20 and only couples to armed donor/acceptors in low yield (Figure 4) [24]. This is analogous to the effect of the very similar benzylidene group, which is deactivating the donor partially due to locking the structure in an unreactive conformation and due

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• acceptors and also act as electron-withdrawing substituents when attached to other aromatic rings thus enhancing benzene’s ring C–H hydrogen bonding [29][30][31]. Recent studies by the Flood group and the Craig group suggested that receptors containing arylated 1,2,3-triazoles could form stable

• containing a halogen (I···N) bond [70]. When chiral organohalides form halogen bonds with chiral acceptors, diastereomeric complexes may be formed. Thus, in 1999, Resnati reported the resolution of racemic 1,2-dibromohexafluoropropane through halogen-bonded supramolecular helices (Scheme 13) [69]. When

Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification

• Anna Zaghi,
• Daniele Ragno,
• Graziano Di Carmine,
• Carmela De Risi,
• Olga Bortolini,
• Pier Paolo Giovannini,
• Giancarlo Fantin and
• Alessandro Massi

Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268

• -unsaturated acceptors [27][28][29]. Indeed, activation of aromatic α-diketones may occur through a double electron-transfer (ET) process triggered by the carbamoyl anion derived from N,N-dimethylformamide (DMF) solvent with catalytic base, which generates an enediolate anion as key reactive species of

• confirmed by the higher residence time (276 min) required to reach satisfactory conversions. Again, benzil 1d proved to be completely ineffective in the addition to α,β-unsaturated acceptors as well (Table 5, entry 7). Conclusion In summary, we have disclosed a practical continuous-flow procedure for the

Computational methods in drug discovery

• Sumudu P. Leelananda and
• Steffen Lindert

Beilstein J. Org. Chem. 2016, 12, 2694–2718, doi:10.3762/bjoc.12.267

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• significant number of H-bond donors and acceptors [39]. Indeed, CDs violate three criteria of the Lipinski’s rule: i) no more than 5 H-bond donors, ii) no more than 10 H-bond acceptors, iii) a molecular mass less than 500 g/mol, and iv) an octanol–water partition coefficient (log P) not greater than 5 [40

• concentrations of modified β-CDs result in rates of cell cholesterol efflux far in excess of those achieved with physiological cholesterol acceptors such as high-density lipoproteins (HDL). Indeed, plasma levels of HDL are inversely associated with cardiovascular morbidity and mortality because this lipoprotein

• with the cholesterol acceptors, the authors proposed that the cholesterol efflux from serum monocytes is the main mechanism and is probably an effective means of inhibiting the development of atherosclerotic plaques. In 2015, Montecucco et al. reported the anti-atherosclerotic action of KLEPTOSE

Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• -workers appeared, Wenwei Lin and a co-worker published conceptually similar catalytic Wittig reactions that were based on their previous research regarding related non-catalytic phosphine-mediated base-free Wittig reactions (Scheme 10) [28]. They started with Michael acceptors 36 to generate products 37

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• Homoleptic zinc(II) complexes of di(phenylacetylene)azadipyrromethene (e.g., Zn(WS3)2) are potential non-fullerene electron acceptors for organic photovoltaics. To tune their properties, fluorination of Zn(WS3)2 at various positions was investigated. Three fluorinated azadipyrromethene-based ligands were

• substitution at the pyrrolic phenylacetylene moieties. The later complexes are expected to be stronger electron acceptors than Zn(WS3)2, and may enable charge transfer from other conjugated polymer donors that have lower energy levels than poly(3-hexylthiophene) (P3HT). Keywords: dye; fluorine; near-IR

• chelation [1][2][3][4]. BF2+-chelated ADP derivatives (Figure 1b) in particular have drawn interest for photodynamic therapy, bio-imaging and light harvesting applications [5][6][7][8]. We have shown that derivatives of Zn(ADP)2 are promising electron acceptors for organic photovoltaics (OPVs) [9][10]. A

TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals

• Mei-Yuan Hsu,
• Yi-Pei Liu,
• Sarah Lam,
• Su-Ching Lin and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164

• dithiol acetal side product 9. Inspired by the results obtained in the synthesis of S-2-deoxyglycosides, we explored the use of numerous alcohols as acceptors in order to directly synthesize O-2-deoxyglycosides from glycals. In Table 2 the reaction of glucal 1 and benzyl alcohol (12) under similar

• attempted to extend the scope of the glycosylation of 3,4,6-O-acetyl- and O-benzylglucal (1 and 3) with other acceptors (Table 3). Under the optimized conditions, glucal 1 reacted with numerous primary, secondary, and tertiary alcohols, including methanol (13), allyl alcohol (14), isopropanol (15), tert

• -glucosides were formed in their corresponding products 33 (71%, 5:1, Table 3, entry 9) and 34 (79%, 4:1, Table 3, entry 10). For the use of monosaccharides as acceptors, primary monosaccharides 22 and 23 gave disaccharides 35 (80%, Table 3, entry 11) and 36 (78%, Table 3, entry 12) respectively in high

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• was calibrated by measuring the ferrocene/ferrocenium (Fc/Fc+) redox peak. The HOMO and LUMO energy levels of the polymers and electron acceptors were calculated from the peak values of the third scans by setting the oxidative peak potential of Fc/Fc+ vs the normal-hydrogen electrode (NHE) to 0.630 V

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• are biosynthesised in seven principal ways (Scheme 2). Those comprise nucleophilic addition of a hydroxy group to electrophiles like epoxides 4, carbonyl groups 6 or Michael acceptors 9, potentially followed by further processing (a–c in Scheme 2). Lactones 12 are formed by transacylation of a

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• the enantioselective reduction of α-substituted conjugate addition acceptors, including catalytic hydrogenation, multiple reviews have already appeared on this topic, and therefore asymmetric catalytic reduction will not be covered here [11][12][13]. Conjugate addition followed by terminal

• high yield and enantioselectivity for both α-alkyl and α-aryl conjugate addition acceptors. Alkyl substrates reacted smoothly at 25 °C (90–98% yield, 90:10 to 95.5-4.5 er) even when R was a more sterically demanding isopropyl or cyclohexyl group. Aryl substrates required lower reaction temperatures and

• additions to other classes of Michael acceptors only being reported more recently. While many examples using sulfur and carbon nucleophiles have been reported, the addition of other heteroatom nucleophiles remains relatively unexplored. This approach for the synthesis of tertiary carbon stereocenters

Modular synthesis of the pyrimidine core of the manzacidins by divergent Tsuji–Trost coupling

• Sebastian Bretzke,
• Stephan Scheeff,
• Felicitas Vollmeyer,
• Friederike Eberhagen,
• Frank Rominger and
• Dirk Menche

Beilstein J. Org. Chem. 2016, 12, 1111–1121, doi:10.3762/bjoc.12.107

• groups [38][39][40][41][42][43], is based on a sequential nucleophilic addition and an intramolecular allylic substitution reaction. It relies on the coupling of different homoallylic nucleophiles of general type 6 to diverse electrophiles 7 such as Michael acceptors, or heteroolefins as for example

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• acceptors in reactions promoted by bifunctional Brønsted bases. 1.2.1 Nitroalkenes as acceptors. Investigation of the base-catalyzed Michael addition reaction of 2-thio-1H-imidazol-4(5H)-ones 4 to nitroalkenes 5 [55] revealed that cinchona alkaloids such as quinine, (DHQ)2Pyr or even thiourea tertiary amine

• doesn’t change after the addition of nitrostyrene. 1.2.2 α-Silyloxyenones as acceptors. Among Michael acceptors, simple α,β-unsaturated esters and amides still are challenging substrates in direct Michael additions and have only been employed in few successful Michael reactions, mainly due to their

• efficient platforms for bidentate coordination in metal catalysis and good precursors of carboxylic acids, ketones and aldehydes upon oxidative cleavage of the keto/diol moiety [72]. More recently, a comprehensive study on the first evidence of the utility of these acceptors in organocatalysis has been

Synthesis and in vitro cytotoxicity of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine

• Štěpán Horník,
• Lucie Červenková Šťastná,
• Petra Cuřínová,
• Jan Sýkora,
• Kateřina Káňová,
• Roman Hrstka,
• Ivana Císařová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2016, 12, 750–759, doi:10.3762/bjoc.12.75

• they can be immediately employed as glycosyl acceptors or readily converted into glycosyl donors. Research in this way is now in progress in our laboratory. Examples of deoxofluorinated hexosamines. Retrosynthetic plan. Preparation of starting 2-azido compounds. Reagents and conditions: (a) NaN3, NH4Cl

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

• with heteroaryl chlorides 92 and 94 to obtain products 93 and 95 in 84% and 35% yield, respectively [66]. These results represent a breakthrough in the direct α-C–H functionalization of piperazines. The generation and trapping of the α-amino radical derived from 87 with radical acceptors under mild

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• acetylated glycosyl bromides 13, 15–20 derived from pyranoses, furanoses and a disaccharide (Figure 2) were prepared as glycosyl donors in one step and high yields starting from the peracetylated sugars. The glycosyl bromides depicted in Figure 2 were subsequently examined in the glycosylation of acceptors

• was selected for the glucosylation reactions of acceptors 6a and 6c with bromide 13, affording compounds 21a and 21c with full β-selectivity. Acetylated tyrosol 9 as glycosyl acceptor reacted only smoothly with 13 under all three studied reaction conditions (Table 1, entries 7–9) affording the

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• (Figure 1). Some examples of these properties are rigidity, disposition of the two stereogenic centers, ability of the hydroxy and amino groups to coordinate to some metals or to act as hydrogen-bond donors/acceptors, the different catalytic activity of these chemical groups and their possible

• -bonding acceptors in their activation through hydrogen-bonding catalysis. The corresponding final esters or amides are obtained after proper treatment of the reaction mixture. During the screening of catalysts, the best enantioselectivity (74% ee) was obtained using ent-4 in the addition of indole (2a) to

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• rings initiated by oxy/aza/sulfa-Michael addition In 2007, Wang and co-workers utilized 2-mercaptobenzaldehydes 163 and α,β-unsaturated systems as Michael acceptors, such as α,β-unsaturated oxazolidinones 164 and maleimides 52, in order to catalyze Michael aldol cascades to construct versatile

• ) pathway of a Michael–retro-Michael–Michael–Michael reaction. The same year Zhao and co-workers reported a novel domino Michael–Knoevenagel reaction between 2-mercaptobenzaldehydes 163 and easily accessible Michael acceptors 169 catalyzed by 9-epi-aminoquinine thiourea 57 (Scheme 55) [76]. Various adducts

Effective in silico prediction of new oxazolidinone antibiotics: force field simulations of the antibiotic–ribosome complex supervised by experiment and electronic structure methods

• Jörg Grunenberg and
• Giuseppe Licari

Beilstein J. Org. Chem. 2016, 12, 415–428, doi:10.3762/bjoc.12.45

• against a variety of bacterial strains, in line with a simulated enthalpic penalty of +8.8 kJ/mol. It has been suggested by Palumbo Piccionello et al., that, though the 1,2,4-oxadiazole ring is isosteric with the oxazolidinone ring and possesses similar hydrogen bond acceptors sites, the lack of

Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

• Ming-Liang Zhang,
• Deng-Feng Yue,
• Zhen-Hua Wang,
• Yuan Luo,
• Xiao-Ying Xu,
• Xiao-Mei Zhang and
• Wei-Cheng Yuan

Beilstein J. Org. Chem. 2016, 12, 295–300, doi:10.3762/bjoc.12.31

• -ketophosphonates [21][22], fluoromethyl ketones [23][24] and isatins [25][26]. Despite these significant advances described above, the use of more challenging ketones with heterocyclic structures as Henry acceptors has remained relatively less explored. In this context, developing a new Henry reaction for the

• work represents the first example of 1H-pyrrole-2,3-diones used as Henry acceptors for the asymmetric reaction. Herein, we report our preliminary results on this subject. Results and Discussion We started our studies with the reaction of ethyl 1-benzyl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrole-3

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

• ][10][11]. This is because NHC complexes are easily obtained by deprotonating imidazolium or benzimidazolium salts and most are relatively stable in air and moisture. They are weak π-acceptors and strong σ-donors and can form strong M–C bonds with transition metal ions compared to trivalent phosphine

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

• extend the annulation reaction to phenols with other Michael acceptors at the ortho-position (such as unsaturated esters, enals and nitroolefins) were not successful. Additionally, a very low yield (ca. 10%) of the product 8aa was obtained when the chalcone formation (7a) and its annulation reaction with