Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

• Ana Čikoš,
• Irena Ćaleta,
• Dinko Žiher,
• Mark B. Vine,
• Ivaylo J. Elenkov,
• Marko Dukši,
• Dubravka Gembarovski,
• Marina Ilijaš,
• Snježana Dragojević,
• Ivica Malnar and
• Sulejman Alihodžić

Beilstein J. Org. Chem. 2015, 11, 1447–1457, doi:10.3762/bjoc.11.157

• into a [4.5]spiroketal [56]. Whichever pathway is applicable, it transpires through loss and regain of chirality either at 8-C (C1) or 10-C (C2) and final formation of the spiroketal 2. Loss and regain of chirality at 8-C proceeds with complete retention of the configuration with the methyl group in an

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

• conformation that imparts helical chirality. Double helically twisted chiral cyclophanes are important macrocycles due to their potential applications in optics and electronics. Kawase and co-workers [121] have reported the synthesis of 8,14,30,36-tetramethoxy[2.0.2.0](1,6)naphthalenophane-1,19-diyne (102

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• complex 8). The coordination geometry of 8 is pseudo-square planar with the four coordination sites occupied by the two nitrogen donors and the two chlorine atoms. The molecule possesses approximate C2 symmetry and its chirality has been confirmed to be the (S,S)-isomer. The Pd–N and the Pd–Cl distances

Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones

• Flavia Pop and
• Narcis Avarvari

Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124

• conformation. Cyclic voltammetry measurements indicate fully reversible oxidation in radical cation and dication species. Keywords: chirality; crystal structures; molecular materials; sulfones; tetrathiafulvalenes; Introduction Chiral tetrathiafulvalene (TTF) derivatives have been addressed for the first

• based on the dimethyl-ethylenedithiotetrathiafulvalene (DM-EDT-TTF) precursor (Scheme 1). Here the racemic salt was found to be metallic, while the enantiopure forms showed semiconducting behavior [10]. One of the most important results is the observation of a synergistic effect between chirality and

• conductivity in enantiopure mixed-valence metallic salts formulated as [DM-EDT-TTF]2[ClO4] [11]. This is referred to as the electrical magnetochiral anisotropy (eMChA) effect. This effect, which translates the influence of chirality on the transport properties measured in a parallel magnetic field [12], was

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

• Masashi Hasegawa,
• Junta Endo,
• Seiya Iwata,
• Toshiaki Shimasaki and
• Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

• carried out by direct C–H activation of the TTF unit, and the chiroptical properties of the resulting polymer were also investigated. Keywords: allene; axial chirality; chiroptical properties; redox; tetrathiafulvalene; Introduction Recently, there has been a growing interest in chiral π-conjugated

• switchable by tuning the electronic structure of the tetrathiafulvalene (TTF) moieties. However, compound 1 exhibited slow racemization in solution under daylight. The chirality of an allene is configurationally firm in general, because the barrier of the rotation of the allenic double bonds is quite high

• small due to the long-range exciton coupling, and hence the Cotton effect derived from the electronic transition of the TTF moiety was not clearly seen. However, both chiral compounds of 3 and PTDPA did not undergo the racemization in daylight. Therefore, the chirality was also preserved in the cationic

Is organic chemistry science – and does this question make any sense at all?

• Andreas Kirschning and
• Thomas A. C. Reydon

Beilstein J. Org. Chem. 2015, 11, 893–896, doi:10.3762/bjoc.11.100

• origin of chirality in bio(macro)molecules and thus in life [12]; the question why biomolecules on earth are based on carbon backbones and not on silicon; the question whether one could imagine other forms of molecular architectures that make up self-repeating systems that develop under evolutionary

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• chirality of the Michael acceptors can be attributed to one of two factors: 1) use of a chiral auxiliary attached to the nitrogen or 2) existing stereochemistry of the acceptor. In this section, we will briefly discuss the use of both types of chiral Michael acceptors in DCA of α,β-unsaturated amides and

An unusually stable chlorophosphite: What makes BIFOP–Cl so robust against hydrolysis?

• Roberto Blanco Trillo,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2015, 11, 313–322, doi:10.3762/bjoc.11.36

• , in Pd catalysts. Keywords: chirality; hydrolysis; phosphorus; rearrangements; terpenoids; Introduction Phosphorus halides are highly reactive intermediates for the synthesis of phosphites and phosphoramidites [1][2][3][4][5], which are widely used, for example, as ligands in catalysts [6][7][8][9

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• relative oxidation potential of the various groups in solution. The group with the lowest oxidation potential is the group that will be oxidized. Chemical oxidations, however, do not have this limitation. They can be selective for one substrate based on steric effects, chirality, or other factors. For this

A facile synthesis of functionalized 7,8-diaza[5]helicenes through an oxidative ring-closure of 1,1’-binaphthalene-2,2’-diamines (BINAMs)

• Youhei Takeda,
• Masato Okazaki,
• Yoshiaki Maruoka and
• Satoshi Minakata

Beilstein J. Org. Chem. 2015, 11, 9–15, doi:10.3762/bjoc.11.2

• chirality [2][3][4][5][6][7][8][9][10][11]. In fact, helicenes have been finding more and more potential applications such as optoelectronic materials, asymmetric catalysts, and chemosensors [9]. Therefore, the development of synthetic methods for the preparation of helicenes which are difficult to access

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• gave almost the same isolated yields of recovered alcohol (S)-(+)-5 and the acetate (R)-(−)-6a with moderate to excellent enantiomeric excess for both compounds (69–100% ee) (Table 3, entries 2 and 3), respectively. Again, a very similar chirality inducement occurred under Lipozyme TL IM catalyzed

• alcohol (+)-5 (L1/L2) were compared, and their spatial location (absolute configuration) was determined in accordance with the signs of their differences (ΔδRSL1 and ΔδRSL2) in both prepared MPA-derivatives 11 and 12 (Figure 2). The chirality of asymmetric carbon in the alcohol (+)-5 could be established

Inherently chiral calix[4]arenes via oxazoline directed ortholithiation: synthesis and probe of chiral space

• Simon A. Herbert,
• Laura J. van Laeren,
• Dominic C. Castell and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2014, 10, 2751–2755, doi:10.3762/bjoc.10.291

• and applications. These range from their use as molecular receptors [2][3][4][5][6], stationary phase modifiers in separation science [7][8][9], and as molecular storage vessels [10][11][12][13]. In the area of molecular recognition, the importance of chirality in the calixarene receptor has been

• shown to be significant [14][15][16][17]. With this in mind, chiral calixarenes have been synthesized, either by the incorporation of a chiral group into the calixarene scaffold, or by the introduction of asymmetry into the structure itself, creating chirality associated with form and termed inherent

• chirality [18]. Efforts to explore the properties of inherently chiral calixarenes have been hampered by the difficulty with which enantiomerically pure or enriched antipodes can be obtained. Until recently, no significantly asymmetric method for functionalizing calix[4]arenes had been developed, with all

Stereoselective synthesis of perillaldehyde-based chiral β-amino acid derivatives through conjugate addition of lithium amides

• Zsolt Szakonyi,
• Reijo Sillanpää and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2014, 10, 2738–2742, doi:10.3762/bjoc.10.289

• ]. Generally, in these transformations, the source of chirality is served by chiral lithium amides, and there are only few examples where chiral α,β-unsaturated esters are applied [23][24][25][26][27]. Easily obtainable chiral monoterpenes, such as (+)-3-carene as well as all the enantiomers of pulegone, α

Preparation of neuroprotective condensed 1,4-benzoxazepines by regio- and diastereoselective domino Knoevenagel–[1,5]-hydride shift cyclization reaction

• László Tóth,
• Yan Fu,
• Hai Yan Zhang,
• Attila Mándi,
• Katalin E. Kövér,
• Tünde-Zita Illyés,
• Attila Kiss-Szikszai,
• Balázs Balogh,
• Tibor Kurtán,
• Sándor Antus and
• Péter Mátyus

Beilstein J. Org. Chem. 2014, 10, 2594–2602, doi:10.3762/bjoc.10.272

• ]-hydride shift with participation of the benzylic hydrogen to result in the zwitterionic iminium ion intermediates A. The 6-endo cyclization of this intermediate gave rac-trans-7a,b with high diastereoselectivity, which was governed by the C-2 chirality center of intermediate A. In contrast to the domino

Total synthesis of the proposed structure of astakolactin

• Takayuki Tonoi,
• Keisuke Mameda,
• Moe Fujishiro,
• Yutaka Yoshinaga and
• Isamu Shiina

Beilstein J. Org. Chem. 2014, 10, 2421–2427, doi:10.3762/bjoc.10.252

• data of astakolactin. This study was partly supported by a Research Grant from the Center for Chirality and Grants-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture, Japan.

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• enantioselectivities probably arise from the embracing properties of the HUGPHOS ligands, which facilitates chirality transfer. Heck cross-coupling Phosphine-assisted Heck reactions strongly depend on the bulkiness of the phosphine used [64]. To assess HUGPHOS-2 in Heck coupling, we focused on the reaction between

• hydroformylation of styrene. In these systems, the high isoselectivity arises from the ligand ability to exclusively generate monophosphine complexes while the high enantioselectivity is a result of the efficient chirality transfer imposed by the embracing character of the chiral CD cavity. To the best of our

Oligomerization of optically active N-(4-hydroxyphenyl)mandelamide in the presence of β-cyclodextrin and the minor role of chirality

• Helmut Ritter,
• Antonia Stöhr and
• Philippe Favresse

Beilstein J. Org. Chem. 2014, 10, 2361–2366, doi:10.3762/bjoc.10.246

• spectroscopy. The magnetic interaction of the monomer with the cavity of RAMEB-CD is obvious in the 2D ROESY NMR spectra as shown in Figure 1 (marked areas). Principally, cyclodextrins and their derivatives are able to discriminate enantiomeric compounds [9][10]. Such chirality recognition is provable with 1H

• NMR spectroscopy because of the different induced shift of the protons which became diastereotopic through complexation [11][12]. Actually, the chirality discrimination of 1 with RAMEB-CD is evident from the different induced shift of the protons 8 at 5.2 ppm (zoomed out in Figure 1). The MALDI–TOF MS

De novo macrolide–glycolipid macrolactone hybrids: Synthesis, structure and antibiotic activity of carbohydrate-fused macrocycles

• Richard T. Desmond,
• Anniefer N. Magpusao,
• Chris Lorenc,
• Jeremy B. Alverson,
• Nigel Priestley and
• Mark W. Peczuh

Beilstein J. Org. Chem. 2014, 10, 2215–2221, doi:10.3762/bjoc.10.229

• backbone of the macrocycle whose chirality is dictated by the absolute configuration of the C4 stereogenic center. The topology is a defining feature of this family of [13]-macrodiolides. By virtue of the planar chirality, [13]-macrodiolides such as 3 have an axis of chirality associated with them. We were

• schematic representation. An axis of chirality associated with the topology of the macrocycle is indicated with a dashed line in b). Structures of 5 and 6 from X-ray crystallographic data; a) and b) side views of 5 (a) and 6 (b) with mean plane of macrocycle in blue and D-glucose in red; c) and d) views of

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

• ), whereas the isoelliptic points supported the formation of only one type of the compound/DNA or RNA complex. The intensity decrease of ds-DNA/RNA CD bands is usually associated with the partial disruption of the polynucleotide helical chirality caused by the binding of a small molecule. The reference

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

• elements, thereby providing suitable chirality, nucleophilicity, basicity, functionality, and rigidity. 2 Enantioselective reactions catalyzed by chiral phosphines Using the chiral phosphines described above as catalysts, a number of highly enantioselective reactions have been achieved, offering a wide

P(O)R₂-directed Pd-catalyzed C–H functionalization of biaryl derivatives to synthesize chiral phosphorous ligands

• Rong-Bin Hu,
• Hong-Li Wang,
• Hong-Yu Zhang,
• Heng Zhang,
• Yan-Na Ma and
• Shang-dong Yang

Beilstein J. Org. Chem. 2014, 10, 2071–2076, doi:10.3762/bjoc.10.215

• reported operation, the substrates of biaryl derivatives that contained phosphate with axial chirality were obtained in high yields using the Suzuki–Miyaura coupling reaction with the assistance of this versatile chiral ligand [31][32][33][34]. We used substituted naphthylboronic acid or ortho-substituted

• -phenylboronic acid to synthesize the corresponding substituted binaphthyl or phenyl-naphthyl skeleton substrates with axial chirality. To maintain the axial chirality within the substrates, a steric hindrance effect at the ortho position of phenylboronic acids was required, rendering the non-ortho substituted

Relay cross metathesis reactions of vinylphosphonates

• Raj K. Malla,
• Jeremy N. Ridenour and
• Christopher D. Spilling

Beilstein J. Org. Chem. 2014, 10, 1933–1941, doi:10.3762/bjoc.10.201

• complete chirality transfer. Various carbon, nitrogen, and oxygen nucleophiles participate in the palladium-catalyzed substitution reactions of phosphono allylic carbonates 1. Vinylphosphonates formed in this way, for example 2a–e (Figure 1), have been used in the synthesis of the natural products

Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum

• Naoya Oku,
• Miyako Matsumoto,
• Kohsuke Yonejima,
• Keijiroh Tansei and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2014, 10, 1808–1816, doi:10.3762/bjoc.10.190

• proton, not observed in the 1H spectrum, was assigned to a hydroxy proton (9-OH). Thus, the planar structure of 1 was determined to be a new 14-membered macrolide. The stereogenic center C13 constitutes an α-acyloxy ketone moiety and deacylation catalyzed by a base may result in the loss of chirality

• -configuration of C12 to the chirality of C13, 3 was treated with NaOMe in methanol, and the obtained product triol 4 was converted to acetonide 5. The conformation of the 2,2-dimethyl-1,3-dioxolane ring in 5 was analyzed by NOESY and HSQC experiments, both of which confirmed a trans relationship of H12 and H13

Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction

• Marina Rubina,
• William M. Sherrill,
• Alexey Yu. Barkov and
• Michael Rubin

Beilstein J. Org. Chem. 2014, 10, 1536–1548, doi:10.3762/bjoc.10.158

• selectivity. Structural modification of the flat ortho-phenylene tether in the Pfaltz ligand through the incorporation of additional chirality elements into the ligand backbone allowed for significant improvement of the enantioselectivity. Thus, ferrocene-based ligands introduced by Dai and Hou [55][56], and

Why a diaminopyrrolic tripodal receptor binds mannosides in acetonitrile but not in water?

• Diogo Vila-Viçosa,
• Oscar Francesconi and
• Miguel Machuqueiro

Beilstein J. Org. Chem. 2014, 10, 1513–1523, doi:10.3762/bjoc.10.156

• simulations were performed using GROMACS 4.0.7 [43][44] and adapted parameters from the GROMOS 56ACARBO [45][46] force field. In all the constant protonation simulations, the neutral secondary amino groups were built in the R configuration. In the constant-pH MD simulations, the chirality of the amino groups