A chiral self-sorting photoresponsive coordination cage based on overcrowded alkenes

• Constantin Stuckhardt,
• Diederik Roke,
• Wojciech Danowski,
• Edwin Otten,
• Sander J. Wezenberg and
• Ben L. Feringa

Beilstein J. Org. Chem. 2019, 15, 2767–2773, doi:10.3762/bjoc.15.268

• supramolecular palladium complexes caused immediate crystallization [22]. Moreover, azobenzenes have been used to functionalize both the interior [23] and exterior [24] of SCCs to photochemically control guest binding and release. Furthermore, incorporation of dithienylethene into the ligands connecting the

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• volatile solvents removal, (iii) the high temperature crystallization step for 90 minutes. Spherical nanoparticles of 21.8 ± 1.3 nm were collected. Crystal quality was assayed by XRD and only the hexagonal β-phase could be detected (Supporting Information File 1). These particles are kept well dispersed in

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• fractionating crystallization. Structure determination by X-ray diffraction analysis revealed marked conformational differences around the CH–C(O–) single bond of E and Z-isomers and extended charge delocalization in the anionic part. Keywords: betaines; multi-component reactions; N-triflylamides; phospha

• E-diastereoisomers, others as E/Z mixtures. In some cases, the two diastereoisomers were separated by fractionating crystallization from a mixed-solvent solution. In the case of 3a, a trace amount (≈2%) of the Z-isomer was detected in the reaction mixture by 1H NMR (the chemical shift of the

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• (III) chloride in methanol in 88% yield (Scheme 1). The synthesis of allylic alcohol 11, a regioisomer of 6, started again from (1R)-α-pinene (1, Scheme 2). Hydroboration of (1R)-α-pinene with borane–dimethyl sulfide adduct (BMS) and crystallization of the product diisopinocampheylborane (dIpc2BH, 84

• added to the reaction mixture and the solution was filtered through a pad of celite. The precipitate was washed with another portion of warm toluene (10 mL). The solvent was removed using a rotary evaporator to give the phosphine oxide. After crystallization from heptane, phosphine oxide 21 (1.612 g, 92

Indium-mediated C-allylation of melibiose

• Christian Denner,
• Manuel Gintner,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2019, 15, 2458–2464, doi:10.3762/bjoc.15.238

• –124 °C (methanol used for crystallization); 1H NMR (600.25 MHz, CDCl3, 25 °C) δ 5.653 (dddd, 3J8,9a = 17.0 Hz, 3J8,9b = 10.2 Hz, 3J8,7b = 7.3 Hz, 3J8,7a = 6.9 Hz, 1H, H-8), 5.449 (dd, 3J4’,3’ = 3.4 Hz, 3J4’,5’ = 1.2 Hz, 1H, H-4’), 5.416 (dd, 3J3,2 = 7.5 Hz, 3J3,4 = 3.3 Hz, 1H, H-3), 5.308 (dd, 3J4,5

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• (H2B(pz)2)2”, with its β-keto ester moiety acting as a second coordination site. Slow crystallization yielded a tetranuclear Fe(II) complex 9, where the base dimeric unit is expanded by an unprecedented trimethoxypyrazolylborate bridging group. The photocyclization of iron complexes is inhibited due to

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• spectra were measured on a GC–MS Varian 1200L (ionizing voltage 70 eV, direct input of the sample) instrument. Elemental analysis was realized on a EuroVector EA-3000. Analytical samples of the compounds were obtained by crystallization from water and further drying at room temperature in air. Microwave

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• subsequent cyclization unlikely. Crystal structure of CotB2wt·Mg2+3·F-Dola resembles the closed, active conformation The structure of CotB2wt·Mg2+3·F-Dola has been obtained by co-crystallization of CotB2wt and FGGDP (PDB-ID 6GGI; [37]), representing the closed, active conformation. Fluorinated substrates

• , such as FGGDP, have been used for the crystallization of other TPSs and have been shown to stick to the active site without undergoing cyclization, trapping the enzyme in a closed state [52][53]. Comparing the overall structure of CotB2wt·Mg2+3·F-Dola to the open conformation of CotB2 reveals major

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• state, as envisioned. Possible reasons could be assigned to substituent effects as demonstrated by Simeth et al. [62]. As recently reported by Schehr et al., reducing agents like DTT, used to prevent enzyme oxidation in crystallization mixtures or in vitro assays, can reduce azo dyes to hydrazine

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

• Arnault Heynderickx,
• Sébastien Nénon,
• Olivier Siri,
• Vladimir Lokshin and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

• THTAA Derivative 3 was prepared from 2,5-dihydroxy-p-benzoquinone and ethylenediamine as brownish-yellow solid according to the recommended procedure (Scheme 1) [8]. Crystallization from butyl acetate produced yellow crystals of THTAA (3) in about 50% yield, still slightly brownish, along with the

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• literature report [32]). This was presumably due to ruthenium undergoing a reductive elimination and the chloride remaining on the triazolium moiety. Crystallization also proved to be futile after many attempts under many different conditions. The only crystals that formed were either found to be the

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• of [KA'] and alkali metal iodides, extracting the ground mixtures with hydrocarbon solvents, and then attempting crystallization of the extracts. This is necessarily an imperfect route to sampling the product space, as definitive characterization of any product(s) depended critically on the

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• [16][18][19], isopropyl 5c [16] and tert-butyl 5d [16][20] as well as for 4-methoxyphenyl ester 5e [21]. However, the corresponding (−)-menthyl esters (2R,1'R)-5f and (2S,1'R)-5f were separated by solvent-driven selective crystallization at low-temperature from ethanol and hexane, respectively. The

• presence of acetic anhydride produced a crude acetamido ester (R)-132 which was transformed into the final N-benzyl amide (R)-130 with of 99.9% ee after crystallization. ʟ-(+)-Furanomycin (Scheme 35) is a natural nonproteinogenic amino acid which showed pronounced antibacterial activity. From several

• pyrrolidin-2-ones (3S,4R,5R,1'R)-183b (by crystallization from cold ethanol) and (3R,4S,5R,1'R)-183b (by flash chromatography). After reduction and hydrogenolysis they were converted into 1,4-dideoxy-1,4-imino-ᴅ-arabinitol and ((2R,3R,4R)-182) and 1,4-dideoxy-1,4-imino-ᴅ-xylitol ((2R,3S,4S)-182

Molecular basis for the plasticity of aromatic prenyltransferases in hapalindole biosynthesis

• Takayoshi Awakawa and
• Ikuro Abe

Beilstein J. Org. Chem. 2019, 15, 1545–1551, doi:10.3762/bjoc.15.157

• , an X-ray crystallization analysis was conducted. The apo structure of AmbP1 was solved at 2.35 Å, and it adopted an ABBA fold [4][5][13]. Interestingly, the apo structure unusually includes the Mg2+ ion in a position nearby the β-barrel, stabilized by hydrogen bonding with N41, E63, and D65 (Figure

• same pH as in the reservoir for crystallization. In this structure (Mg2+-free structure), the distance from C-1 of GSPP to C-2 of 1 (Figure 4A, a: 3.3 Å) is closer than that to C-3 of 1 (Figure 4A, b: 4.6 Å), unexpectedly indicating that this is a model for the C-2 prenylation. Next, the soaking

Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation

• Sebastian Haferkamp,
• Andrea Paul,
• Adam A. L. Michalchuk and
• Franziska Emmerling

Beilstein J. Org. Chem. 2019, 15, 1141–1148, doi:10.3762/bjoc.15.110

• the inclusion of the base led to crystallization of the corresponding products 3a–c during the milling process. In contrast, crystallization during the base-free reaction required an ex situ aging step. Figure 1 shows the XRPD pattern of the substrate 2 and the product 3a. Due to the liquid state of

• inclusion of base catalyst in the final product, we suggest this difference to be the result of a templating effect, which dominates at higher concentrations. For the reaction of meta- and ortho-substituted substrates, crystallization occurs directly into the monoclinic phase, regardless of milling

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• dispersion and crystallization of CB[7] and PCL in the composite nanofibers, XRD patterns of neat PCL nanofibers and all PCL/CB[7] nanofibers were recorded (Figure 2). PCL is a semi-crystalline polymer, and neat PCL nanofibers elicit two strong and sharp characteristic diffraction peaks at 2θ = 22° and 2θ

• continuous phase and crystal aggregates of PCL and CB[7]. At low CB[7] contents, the majority of the CB[7] molecules could disperse homogeneously in the PCL matrix, partly causing the disruption of continuous phase and crystallization of PCL and CB[7]. With the increase of CB[7] content, there are more

• that temperature. There is only a very wide and weak peak in the heating cycle, which was caused by evaporating of water from the cavity of CB[7] (Figure S7 in Supporting Information File 1). As can be deduced from Figure 3, all electrospun webs exhibit obvious melting and crystallization peaks below

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• . employing substitutional disorder, achieved the co-crystallization of six components [28]. As for positional disorder, it generally indicates the same molecule or assembly can adopt more than one favourable conformation. From this perspective, disorder can be considered as a special case of a co-crystal or

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• to crystallization of [Zn2L(μ-azo-OH)][Zn2L(μ-azo-O)]·BPh4·4MeCN·3H2O (3'·4MeCN·3H2O). The asymmetric unit contains one [Zn2L(μ-azo-OH)]+ cation (Figure 4), one [Zn2L(μ-azo-O)] neutral complex (comprising a doubly deprotonated co-ligand), one BPh4− anion, and MeCN and H2O solvate molecules. Both

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• , which has to be separated either by selective crystallization or by chromatography. The first concern was to verify that using the two most commonly used procedures for 6-monotosylation, the substitution by the second tosyl moiety is still selective for the primary rim of β-CD. For a straightforward

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• ; no crystallization was observed even after several days at rt. Similar properties were displayed by product 13d, which did not crystallize at all and was analyzed as an oily material. 1-Adamantyloxy-4,5-dimethyl-3-pentyloxy-1H-imidazolium bromide (13a): Yield: 325 mg (79%). Beige crystals; mp 73 °C

• mixture) as an eluent. The required product was isolated as a crystalline material. Additional crystallization from diisopropyl ether/CH2Cl2 mixture afforded analytically pure imidazolium salt 15. 1,3-Di(adamantyloxy)imidazolium bromide (15): Yield: 190 mg (41%). Colorless crystals; mp ca. 160 °C (dec

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• (1R,3S)-HPA-12 (2) used the chiral pool approach [15][16], crystallization-induced asymmetric transformation [17], diastereoselective reduction of γ-aryl-γ-oxo-β-amino alcohol [18], cycloaddition of oxime with alkenes [19], enantioselective carbonyl reduction followed by an organocatalyzed α-amination

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• generation of the protected β-NR+Br− 8a, which was isolated by crystallization from a 5:1 acetone/t-BuOMe mixture in 90% overall yield from 2a [27]. Note that dry acetonitrile was also used as a solvent in the glycosylation step instead of liquid SO2 but the yields of acetylated NR+Br− 8a were lowered (65

• %) [27]. Removal of the acetyl groups from 8a under optimized conditions (3 equivalents of NH3, 1 M in MeOH, at −3 to −5 °C for 20 h), followed by crystallization from a 1:5 mixture of MeOH/acetone afforded β-NR+Br− as a crystalline solid in high yield (80%) [27]. It should be noted that Lee et al. [27

• % of the α-anomer. This anomer was removed from the crude mixture by chromatography on activated charcoal and crystallization to afford the desired β-NR+OTf− in 58% yield. The predominant formation of the β-isomer of NR+ is due to the generation of a type F cationic intermediate in the course of

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• group, to determine the effect of the spacer length on POSS crystallization ability and the composition dependence of physical properties of the copolymers [49]. A series of homopolymers and random copolymers were synthesized in the presence of third generation Grubbs catalyst Ru-6 in CH2Cl2, at room

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• trimethyl orthoacetate the enantiomerically pure bromomethoxy derivative (4R,5R)-37 was prepared after crystallization of the reaction mixture. The precursor of the carboxymethyl group was first introduced with full retention of configuration employing a stannate chemistry to give (4R,5R)-38 after removal

Green synthesis of new chiral 1-(arylamino)imidazo[2,1-a]isoindole-2,5-diones from the corresponding α-amino acid arylhydrazides in aqueous medium

• Nadia Bouzayani,
• Jamil Kraїem,
• Sylvain Marque,
• Yakdhane Kacem,
• Abel Carlin-Sinclair,
• Jérôme Marrot and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2018, 14, 2923–2930, doi:10.3762/bjoc.14.271

• in a trans-orientation with H(4). In addition, various crystallization tests were carried out in order to confirm the absolute stereochemistry by X-ray diffraction. The chiral 3-(2-(methylthio)ethyl)-1-(phenylamino)-1H-imidazo[2,1-a]isoindole-2,5(3H,9bH)dione (5f) crystallized [44][45][46][47][48][49