Inclusion complexes of β-cyclodextrin with tricyclic drugs: an X-ray diffraction, NMR and molecular dynamics study

• Franca Castiglione,
• Fabio Ganazzoli,
• Luciana Malpezzi,
• Andrea Mele,
• Walter Panzeri and
• Giuseppina Raffaini

Beilstein J. Org. Chem. 2017, 13, 714–719, doi:10.3762/bjoc.13.70

• compound 1. Compounds 1 and 2 are not planar and the exocyclic double bond prevents the free rotation of the side chain with respect to the ring system. Consequently, 1 and 2 show inherent chirality [9] as lacking of symmetry elements. The main purpose of the work is the comparison of the structural

Studies directed toward the exploitation of vicinal diols in the synthesis of (+)-nebivolol intermediates

• Runjun Devi and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2017, 13, 571–578, doi:10.3762/bjoc.13.56

• Runjun Devi Sajal Kumar Das Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam-784028, India 10.3762/bjoc.13.56 Abstract While the exploitation of the Sharpless asymmetric dihydroxylation as the source of chirality in the synthesis of acyclic molecules and saturated

• that a large number of racemic and asymmetric syntheses of nebivolol and their intermediates have been described in the literature, however, the Sharpless asymmetric dihydroxylation has never been employed as the sole source of chirality for this purpose. Keywords: dihydroxylation; epoxide-ring

• Sharpless asymmetric dihydroxylation as the sole source of chirality [27]. For the synthesis of chroman derivative 2, first a base-mediated intramolecular SNAr reaction was envisioned for the aryl C–O bond formation under transition-metal-free conditions [28][29][30]. The additional benefit of this strategy

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• controlling the configurational outcomes. Finally, where chirality is introduced, post-PKS processing reactions also proceed with defined stereochemistry, although this aspect will also not be discussed in this article. The following sections will address the role of each of the principal PKS domains in

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

• form the corresponding salts, and these generated in situ ion pairs were treated with silyl enol ethers in the presence of chiral catalysts L2–L4 to form chiral addition products. High levels of chirality transfer were generally observed for various 6-membered nitrogen-containing heterocyclic

• as potential catalysts, and chiral catalyst L25 was identified as the catalyst of choice. Although no chirality transfer was observed during the reduction of 2-phenylquinoline, L25 was found to be a very active catalyst promoting transfer hydrogenation of a C=N group containing heterocycles and

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

• conjugates of racemic naringenin ((±)-1) with pyrrolidine-2-one with C-6–C-5” and C-8–C-5” linkage, respectively. Due to the two chirality centers, four possible stereoisomers exist for each regioisomer, and accordingly, the isolated substances were verified to be 1:1 mixtures of two diastereoisomeric

A new and expeditious synthesis of all enantiomerically pure stereoisomers of rosaprostol, an antiulcer drug

• Wiesława Perlikowska,
• Remigiusz Żurawiński and
• Marian Mikołajczyk

Beilstein J. Org. Chem. 2016, 12, 2234–2239, doi:10.3762/bjoc.12.215

• (−)-1a obtained herein has the absolute configuration R at the C-2 stereogenic center. As the chirality at this carbon atom remains unchanged in the four-step conversion of (+)-3 into (−)-1a, the same chirality has to be assigned to the corresponding carbon atom (now C-3) in (+)-3. Taking into account a

Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

• Reji Thomas and
• Nobuyuki Tamaoki

Beilstein J. Org. Chem. 2016, 12, 2211–2215, doi:10.3762/bjoc.12.212

• ; cyclic compound; enantiomer; stereostructure; X-ray crystal analysis; Introduction Chirality is a topic of fundamental importance in several branches of science [1][2][3][4][5]. Homochirality in nature was one of the most important challenges for researchers and the origin is still unsolved [6][7][8

• pharmaceutical ingredients [11]. In addition to the special interest in molecular chirality in diverse fields of biology and pharmaceutical chemistry, several chiral molecules have been synthesised and studied for their stereostructure-dependent physical properties such as optical activity [12][13][14][15][16

• chirality methods [28][29], NMR spectroscopy [30][31][32], X-ray diffraction [33][34][35], etc. In addition to these methods, many researchers explored a combination of vibrational circular dichroism and quantum mechanical calculations to determine the absolute stereostructures [36][37][38]. Among various

Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291

• Peng Zhang,
• Xiao-Ming Li,
• Xin-Xin Mao,
• Attila Mándi,
• Tibor Kurtán and
• Bin-Gui Wang

Beilstein J. Org. Chem. 2016, 12, 2012–2018, doi:10.3762/bjoc.12.188

• Cotton effects (CEs) had the same sign for conformer A and B, while the lower-wavelength (<250 nm) CEs were significantly different. The hindered rotation along the biaryl linkage may have implied an additional stereogenic element, which would have enabled atropodiastereomers with axial chirality. In

• order to explore the possibility of axial chirality, torsional angle scans were performed on the lowest-energy M (conformer A) and P (conformer B) helicity gas-phase conformers or atropodiastereomers. Rotational energy barriers between the two isomers were estimated to be ca. 35–42 kJ/mol for TS1 (ωC12

• showed that there is no axial chirality in 1, and equilibrating conformers with M and P helicity are present in solution as obtained in the conformational analysis. The Boltzmann-weighted ECD spectra calculated for both the gas-phase and the solvent model conformers of (2R,3R)-1 at B3LYP/TZVP, BH&HLYP

Enantioselective addition of diphenyl phosphonate to ketimines derived from isatins catalyzed by binaphthyl-modified organocatalysts

• Hee Seung Jang,
• Yubin Kim and
• Dae Young Kim

Beilstein J. Org. Chem. 2016, 12, 1551–1556, doi:10.3762/bjoc.12.149

• properties [5], enzyme inhibition [6], peptide mimetic function [7], and herbicidal properties [8]. Since the biological activity of α-aminophosphonate derivatives is dependent upon the chirality of the α-position to the phosphorus atom, asymmetric synthesis of α-aminophosphonates has received considerable

Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O)”s: functionalization, rotational barriers and non-covalent interactions

• Golo Storch,
• Sebastian Pallmann,
• Frank Rominger and
• Oliver Trapp

Beilstein J. Org. Chem. 2016, 12, 1453–1458, doi:10.3762/bjoc.12.141

• ][6], palladium [7][8], platinum [9][10] and gold [11][12][13] in combination with chiral co-ligands or counter ions that are used after alignment of the ligand’s axial chirality. One major advantage of stereodynamic ligands is that there is no need for separate preparation of one ligand enantiomer as

• long as their chirality can be controlled by chiral additives or auxiliaries. In addition, the simultaneous presence of both axially chiral BIPHEP enantiomers can be beneficial as this allows bidirectional control of enantioselectivity depending on temperature [14][15]. In this approach, both product

A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

• Oksana S. Mikhalchenko,
• Dina V. Korchagina,
• Konstantin P. Volcho and
• Nariman F. Salakhutdinov

Beilstein J. Org. Chem. 2016, 12, 648–653, doi:10.3762/bjoc.12.64

• -fluorohexahydro-2H-chromenes under the developed conditions, the reaction occurs with inversion of configuration. Keywords: chirality; fluorine; halo-Prins reaction; isopulegol; monoterpene; Introduction Recently, we have found that a reaction between para-mentha-6,8-dien-2,3-diol (1) and aromatic aldehydes in

New synthetic strategies for xanthene-dye-appended cyclodextrins

• Milo Malanga,
• Andras Darcsi,
• Mihaly Balint,
• Gabor Benkovics,
• Tamas Sohajda and
• Szabolcs Beni

Beilstein J. Org. Chem. 2016, 12, 537–548, doi:10.3762/bjoc.12.53

• scaffold. Because of the chirality of the cyclodextrin part, the two phenyl rings of the xanthene moiety are formally diastereotopic, and consequently, anisochronous even without any complexation. This fact can be proven by recording the 1H NMR spectrum of the Rho-β-CD in deuterated DMSO, a solvent known

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

• ; bifunctional; organocatalysis; hydrogen bonding; Introduction The structural and chemical properties of the 1,2-aminoindanol scaffold 1 have transformed aminoindanol derivatives into versatile building blocks for the construction of catalysts and the efficient induction of chirality in asymmetric processes

• amino groups. Although the aminoindanol scaffold appears in the structure of different catalysts (providing a suitable way to induce chirality), it is not always directly involved in the bifunctional activation of the substrates [17]. Herein, we show only those cases where the aminoindanol moiety

• through an organocatalyzed asymmetric domino-Michael addition/Henry reaction (Scheme 8) [36]. These heterocyclic products are important chiral building blocks for the synthesis of organocatalytic frameworks and ligands for chiral metal complexes, both with the potential ability to induce chirality. They

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

• enantioselectivity (it is well known that (S)-linezolid is the only active enantiomer) of the recognition process [16][42]. Again, the working-shell was used for this purpose as starting structure. The chirality of linezolid was inverted in place inside the receptor. (R)-Linezolid was rotated by 180° around an

Self and directed assembly: people and molecules

• Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

• group were developing carbohydrate receptors from what looked like simple molecules requiring just one or two steps to synthesize. Therefore, while working with the late Takaaki Harada, we developed a simple colorimetric system able to “read-out” the chirality of sugars. The system we developed used the

• colour of liquid crystals to determine chirality and was quickly prepared in just two steps. The addition of our D-glucose boronate complex to a liquid crystal system the colour changed from green to red, however for the L-glucose system the colour changed from green to blue [11][12] (Figure 2 depicting

• acid spontaneously self-assemble to quantitatively form a stable complex. Interestingly, when the chirality of the binol or amine was fixed the 1H NMR of the complexes formed using a scalemic mixture of the other chiral partner (diol or amine) results in a 1H NMR where signals due to both

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• (S)-sarin is levorotatory. Chirality has been attributed following the reviewed rules of Cahn, Ingold and Prelog [63][64] which classified the oxygen atom of the P=O bond as the minor priority compared to the alkoxy substituents [65]. In their 1988 work, Benschop and De Jong stated that the nerve

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• a wide range of molecular and supramolecular architectures derived from the simple glycoluril motif [28]. Another early molecular tweezer developed by Harmata was notable because of its chirality. Harmata and his undergraduate student, Tom Murray (who later obtained his Ph.D. in my group), showed

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• into the substrates, has emerged as a powerful tool for constructing natural products and useful ligands with axial chirality. Based on asymmetric desymmetrization and kinetic resolution strategies, a series of efficient copper-catalyzed systems have been developed for the formation of C–C, C–N, C–O

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

• Antonia Di Mola,
• Maximilian Tiffner,
• Francesco Scorzelli,
• Laura Palombi,
• Rosanna Filosa,
• Paolo De Caprariis,
• Mario Waser and
• Antonio Massa

Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279

• ]. The racemization probably occurs on the product 9, via the mechanism reported in Scheme 3, as a slower process than the decarboxylation itself. The cleavage of the C–N bond and the formation of the acyclic intermediates 11 with the consequent loss of chirality is probably favored by the protonation of

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

• nitroalkenes has been studied in the presence of two bifunctional catalysts both containing the same absolute chirality at the carbon backbone. The reaction performed in similar conditions allows us to control the syn or anti selectivity of the Michael adduct obtaining good yields and high enantiocontrol in

• of bifunctional tertiary amine/squaramide catalysts [28][29][30][31][32] and, interestingly, we found that catalysts containing the same backbone chirality provided different diastereoisomers, thus allowing the development of a diastereodivergent process. In this report, we wish to present the

• ][53][54][55][56][57][58][59][60][61] with the same absolute chirality, the stereochemical outcome of the reaction can be controlled to provide the corresponding Michael adducts with two stereocentres, one of them being quaternary, and allowing the preparation of the desired diastereoisomer at will

[2.2]Paracyclophane derivatives containing tetrathiafulvalene moieties

• Laura G. Sarbu,
• Lucian G. Bahrin,
• Peter G. Jones,
• Lucian M. Birsa and
• Henning Hopf

Beilstein J. Org. Chem. 2015, 11, 1917–1921, doi:10.3762/bjoc.11.207

• a mixture of inseparable isomeric tetrathiafulvalenes 7 in 17% yield. Since compound 6 already exhibits planar chirality (racemate Rp/Sp), the theoretical number of stereoisomers of the tetrathiafulvalene 7 should be six as follows: cis-(Sp,Sp) with cis-(Rp,Rp) and trans-(Sp,Sp) with trans-(Rp,Rp

The simple production of nonsymmetric quaterpyridines through Kröhnke pyridine synthesis

• Isabelle Sasaki,
• Jean-Claude Daran and
• Gérard Commenges

Beilstein J. Org. Chem. 2015, 11, 1781–1785, doi:10.3762/bjoc.11.193

• step leading to the corresponding acylpyridinium iodide 5, the asymmetric ligands 6–8 were obtained by condensation with various α,β-unsaturated enones with good to excellent yield (see Supporting Information File 1 for the full experimental data). Von Zelewsky et al. showed that pinene-based chirality

• of 3.425(1) Å, resulting in a slippage of 1.54 Å. The absolute configuration is established by the occurrence of the known chirality of the starting material as (−)-(1R,5S)-myrtenal was used. Crystals of complex 9 were obtained by slow evaporation of a solution of the compound with

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• yield of 75%. Phenyl- and 2-thienylacetic acids afforded adducts accompanied by the dimers bibenzyl (18%) and 1,2-di(thiophen-2-yl)ethane (27%), respectively. Significantly, Boc-protected α-amino acids also proved amenable and yielded adducts as 1:1 mixtures of stereoisomers. Chirality was not preserved

Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

• Sara J. Krivickas,
• Chiho Hashimoto,
• Junya Yoshida,
• Akira Ueda,
• Kazuyuki Takahashi,
• John D. Wallis and
• Hatsumi Mori

Beilstein J. Org. Chem. 2015, 11, 1561–1569, doi:10.3762/bjoc.11.172

• chirality, but also the introduced intermolecular hydrogen bonds involving the hydroxymethyl groups, perchlorate anion, and the included solvent H2O. Keywords: BEDT-TTF; chiral molecular crystal; hydrogen bonding; hydroxy group; molecular conductors; Introduction The chiral crystals without an inversion

• due to their ability to form radical cation salts with interesting conductive and magnetic properties (Figure 1). The influence of chirality in the TTF molecules on the crystal structure and physical properties has been shown by Avarvari’s (R)-, (S)- and racemic (±)-(ethylenedithio(tetrathiafulvalene

• chirality, (R,R) or (S,S), are arranged side-by-side along the b-axis. The charge of each molecule is estimated by bond analyses; as shown in Table S2 (Supporting Information File 1) [24], the charges of molecules A, B, and C are +0.59(8), +0.23(7), and +0.18(8), respectively. In the (+) stacking column

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

• Piotr Roszkowski,
• Jan. K. Maurin and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2015, 11, 1509–1513, doi:10.3762/bjoc.11.164

• )-(+)-epinastine. Chirality was introduced in a key step by asymmetric transfer hydrogenation. This synthetic procedure could be used for the preparation of other compounds variously substituted at the aryl rings. The structure of mianserin 1 and epinastine 2. Catalysts used in ATH. The ORTEP diagram for X-ray