Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• fluorination reaction [78]. The groups of Duan and Lin have also very heavily been engaged in the systematic design of highly active bifunctional cinchona alkaloid-based ammonium salt catalysts that contain an additional H-bonding donor [43][44]. Very impressively, they succeeded in synthesizing and testing

• phosphoric acid G2 under basic conditions (leading to the sodium salt of G2 which then acts as the PTC in this reaction) [57] (Scheme 5). The authors propose a bifunctional activation mode of the catalyst for this reaction by simultaneously coordinating the cation 8 via ion pair formation and by H-bonding

• strategy. Hereby both, approaches relying on either asymmetric metal- or organocatalysis, have been well-investigated already [105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120][121][122]. In the field of non-covalent asymmetric organocatalysis, chiral H-bonding catalysis [37

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• the CD macrocycle’s dimensions. The host–guest interactions established in the cavity are of van der Waals type, whereas between parts of the guest extending out of the cavity and the host’s hydroxy groups are H-bonding interactions and/or of electrostatic nature. CDs have been studied and used for

• stronger H-bonding of the carboxyl group, as well as more favorable methyl–phenyl interactions inside the cavity. In contrast, no discrimination is shown by β-CD for (R)- and (S)-flurbiprofen [11], since the crystals grown from the racemic mixture have both enantiomers enclosed (as a head-to-head dimer) in

• dimensions and same packing of β-CD dimers) there are differences regarding the positioning of the guest molecules, the D-enantiomer being ordered, whereas the L- enantiomer extensively disordered. This disparity seems to be determined by subtle hydrophobic differences and H-bonding interactions among guests

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• addition, the electrophilicity of the reacting carbon center of nitrovinylacetamide is likely enhanced by H-bonding, thereby enabling the Michael addition to construct a unique quaternary stereogenic center complex A which would cyclize concurrently via Henry reaction to give the product 3 and regenerates

An eco-compatible strategy for the diversity-oriented synthesis of macrocycles exploiting carbohydrate-derived building blocks

• Sushil K. Maurya and
• Rohit Rana

Beilstein J. Org. Chem. 2017, 13, 1106–1118, doi:10.3762/bjoc.13.110

• inherent properties including stability towards acid–base hydrolysis, active participation in H-bonding, dipole–dipole and π-stacking interactions [37][64][65][66]. The reaction would then afford a range of acyclic precursors, which could then undergo the intramolecular cyclization reaction to furnish the

A new class of organogelators based on triphenylmethyl derivatives of primary alcohols: hydrophobic interactions alone can mediate gelation

• Wangkhem P. Singh and
• Rajkumar S. Singh

Beilstein J. Org. Chem. 2017, 13, 138–149, doi:10.3762/bjoc.13.17

• LMWGs can immobilize organic solvents (forming organogels) and water or aqueous solvents (forming hydrogels) under different experimental conditions. Gels, so formed are supramolecular in nature as they result from self-assembly of the gelator molecules through secondary interactions like H-bonding, π

• ][21][22]. As mentioned above, developing a new gelator is still largely a trial and error method. The most widely used design strategy involves the inclusion of structural components favouring intermolecular non-covalent interactions (like H-bonding, π-stacking, donor–acceptor interaction, metal

• coordination, ionic, hydrophobic forces, etc.) into the gelator molecular structure and studying their gelation behaviour. H-bonding interaction (present in amide, urea, carbamate linkages, etc) alone or in combination with other interactions is the most extensively used strategy in the design of gelators [23

Synthesis of acylhydrazino-peptomers, a new class of peptidomimetics, by consecutive Ugi and hydrazino-Ugi reactions

• Angélica de Fátima S. Barreto,
• Veronica Alves dos Santos and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2016, 12, 2865–2872, doi:10.3762/bjoc.12.285

• (hydrazino turn) due to the presence of intramolecular H-bonding interactions (Figure 3), which is similar in nature to a natural peptide β-turn. As already pointed out, this can improve the proteolytic stability of the natural peptide while preserving its biological activity. Other changes in peptoid

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

• supramolecular complexes with anions [32][33][34]. The stability of such complexes correlated with the number of C–H bonds that could be formed by the receptor, and strong binding comparable to the more traditional X–H bonding based hydrogen bond donors was observed for the receptors forming 5–9 hydrogen bonds

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

• -azathymine (4a) by a sulfur atom changes the pattern of the TP catalyzed glycosylation of 6-aza-2-thiothymine (5a), imparting the reaction reversible character (Figure 4). UP was practically unable to catalyze the synthesis of the nucleoside 5b (Figure 1). Again, unlike the base/Gln166 H-bonding mode

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• diastereoselectivities (all >95:5 dr) and enantioselectivities (up to >99% ee, Scheme 58) [75]. Mechanistic studies showed that this cascade reaction proceeded via a vinylogous Michael addition/Friedel–Crafts process involving a dual H-bonding activation of substrates. In 2015, Wang and co-workers reported Lewis acid

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• before it moves back to the cationic hetarene in a subsequent relaxation process (Scheme 4). In protic solvents, the bromide ion is still stabilized by H-bonding. In contrast, in aprotic polar solvents the anion cannot be stabilized sufficiently which leads to an increased energy of this state. As a

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• bathochromic shift together with an emission-band broadening in contrast to their emission spectra recorded in solution. The supramolecular arrangement in the solid state of indenopyrone 6a is ensured by a number of non-covalent interactions such as intermolecular H-bonding, C–H···π and π···π contacts

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• . Surprisingly, three nongelators exhibited Hirshfeld surface areas similar to the gelators, suggesting the types of intermolecular interactions (e.g., van der Waals, H-bonding, π-stacking) were similar amongst the gelators and nongelators. Because this analysis involves counting interactions without weighting

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• -bonding modes arise in the supramolecular polymeric network, i.e., an intramolecular H bonding with the β- and γ-phosphate groups of ATP2− and an intermolecular H bond between the α-phosphate and another amidoferrocenyl group. Redox properties of polycationic copolymers containing the complex [Fe(η5-C5H5

• used to prepare modified Pt electrodes with high stability and good qualitative sensing of ATP2− anions. It was supposed that the triethylene glycol domains in the block copolymers favor the amidoferrocene–ATP interactions by encapsulation. Astruc assumed that during the recognition process different H

Inclusion complexes of 2-methoxyestradiol with dimethylated and permethylated β-cyclodextrins: models for cyclodextrin–steroid interaction

• Mino R. Caira,
• Susan A. Bourne,
• Halima Samsodien and
• Vincent J. Smith

Beilstein J. Org. Chem. 2015, 11, 2616–2630, doi:10.3762/bjoc.11.281

• protruding from the central DIMEB complex unit (orange) within the space created by the quartet of displaced neighbouring host molecules (d), H-bonding between the representative A-ring hydroxy group –O22–H and three neighbouring CD units mediated by water molecules (blue spheres) (e), and the extended

Organocatalytic and enantioselective Michael reaction between α-nitroesters and nitroalkenes. Syn/anti-selectivity control using catalysts with the same absolute backbone chirality

• Jose I. Martínez,
• Uxue Uria,
• Maria Muñiz,
• Efraím Reyes,
• Luisa Carrillo and
• Jose L. Vicario

Beilstein J. Org. Chem. 2015, 11, 2577–2583, doi:10.3762/bjoc.11.277

• one proposed in Scheme 3 [64]. This involves the activation of the nucleophile by the squaramide moiety of the bifunctional catalysts 4 and 6 through the formation of multiple H-bonding interactions and the simultaneous interaction between the nitroalkene acceptor and the ammonium salt moiety, the

Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

• Xiang Sun,
• Guoqiao Lai,
• Zhifang Li,
• Yuwen Ma,
• Xiao Yuan,
• Yongjia Shen and
• Chengyun Wang

Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255

• nanomaterials is generally accepted to be the self-assembly of supermolecules, which is constructed through weak noncovalent interactions such as π–π stacking, van der Waals interactions, charge transfer and H-bonding interactions [3][4][5][6]. Generally speaking, H-bonding interactions are the key

• derivatives to generate an H-bonding chain. Results and Discussion Synthesis and characterization The synthetic routes for two newly designed TTF derivatives containing one or two urethane groups are shown in Scheme 1. Compounds 2 [17], 3 [18], 4 [19], 5 [19], 6 [18][20] and 7 [18][21] were synthesized from

Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides

• Svetlana F. Malysheva,
• Alexander V. Artem’ev,
• Nina K. Gusarova,
• Nataliya A. Belogorlova,
• Alexander I. Albanov,
• C. W. Liu and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 1985–1990, doi:10.3762/bjoc.11.214

• structure, strong intermolecular H-bonding interactions between the O–H hydrogen and P=O oxygen atom of a second molecule {O(1)–H(1)···O(2), 1.80(6) Å; O–H···O angle, 174.9(7)°} leads to the formation of 1D polymeric chains along the b-axis (Figure S1, Supporting Information File 1). In FTIR spectra of 3a–h

Are D-manno-configured Amadori products ligands of the bacterial lectin FimH?

• Tobias-Elias Gloe,
• Insa Stamer,
• Cornelia Hojnik,
• Tanja M. Wrodnigg and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 1096–1104, doi:10.3762/bjoc.11.123

• explained by the tilted fashion in which Amadori products are complexed by FimH. They are lifted from the bottom of the CRD and this results in compromised H-bonding and weak affinity. We learn from this interdisciplinary study that it is critical to utilize the Amadori rearrangement for the synthesis of

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• the aggregates change from flower-like, network and rod with different sizes. By using IR and XRD characterization, it is found that intermolecular H-bonding, the solvents and van der Waals interaction are the main contributions to the specific superstructure. Keywords: azobenzene; cholesterol

• intermolecular H-bonding, the solvents and van der Waals interaction are the main contributions to the specific superstructure. Results and Discussion To investigate the photoresponsiveness of these compounds, the dilute THF solution of compounds were irradiated by UV and visible light. Figure 1a shows an

• ethanol, isopropanol and 1-butanol. Based on the results of SEM, IR and XRD, it demonstrated that the solvents, intermolecular H-bonding, and van der Waals interaction affected the aggregation mode and morphology of gels. These results can be applied in fields of design and development of novel

Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

• Marcel Mirel Popa,
• Emilian Georgescu,
• Mino R. Caira,
• Florentina Georgescu,
• Constantin Draghici,
• Raluca Stan,
• Calin Deleanu and
• Florea Dumitrascu

Beilstein J. Org. Chem. 2015, 11, 1079–1088, doi:10.3762/bjoc.11.121

• motifs with graph-set descriptor R22(6) occur [33] resulting in a more extensive H-bonding in the crystal of 8 than in that of 6. This is consistent with their significantly different melting points (131–133 °C for 8 and 75–78 °C for 6). In both crystals, C–H…N hydrogen bonding is complemented by offset

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• restricted intermolecular H-bonding ring formed. Subsequent the fluoride-triggered ESPT occurred, which displayed ‘turn-on’ fluorescence. Conclusion In conclusion, a new benzimidazole-based BIP has been developed which is selective for the recognition of F− also in the presence of anions with similar

Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

• Lee Trollope,
• Dyanne L. Cruickshank,
• Terence Noonan,
• Susan A. Bourne,
• Milena Sorrenti,
• Laura Catenacci and
• Mino R. Caira

Beilstein J. Org. Chem. 2014, 10, 3136–3151, doi:10.3762/bjoc.10.331

• since each of the phenolic groups (–O1A–H1A and –O1B–H1B) engages in bifurcated H-bonding, the second acceptor being a disordered water oxygen atom O7W, located at distances 2.60(1) Å and 2.80(1) Å from O1A and O1B respectively. Another important feature of the inclusion geometry relates to the guest

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• /RNA binding sites allowed H-bonding-based recognition of some complementary polynucleotide sequences. However, the recognition pattern was not straight-forward; for instance N5-protonated phenanthridinium–adenine derivative 12 successfully recognized a complementary poly(U) sequence [72] (Scheme 23

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

• Marijana Radić Stojković,
• Marko Škugor,
• Łukasz Dudek,
• Jarosław Grolik,
• Julita Eilmes and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

• ]). Namely, parameters such as the groove width and depth, steric obstructions like the amino groups of guanine, H-bonding patterns, as well as polynucleotide charge density and the curvature of the ds-helix backbone all differ significantly across the double stranded examples mentioned above (Table S1

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• metalloradical catalysis (MRC). (A) Potential H-bonding interaction in postulated nitrene radical complex of [Co(D2-Por*)]. R* represents a chiral unit. (B) Geometry corresponding to the minimum energy from simplified computer modeling by molecular mechanics with Spartan 10. The P=O…H–N distance of (1.87 Å