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

• compounds. Notably, Bard and co-workers investigated the photo-Kolbé reaction, in which simple carboxylic acids RCO2H were decarboxylatively reduced to the corresponding alkanes RH on irradiation with platinized TiO2 in CH3CN under anaerobic conditions [35][36][37]. Only adamantane, from adamantane-1

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• and chloroacetyl chloride. The crude nitrile product 81 was then collected in a batch vessel and isolated in pure form after crystallisation and washing with n-heptane. Alkylation of 81 with the corresponding amino-adamantane derivate in the presence of excess K2CO3 following an existing batch

• adamantane-derived aminoester 119 [95] completed this flow synthesis. Meclinertant (103) was subsequently obtained after batch deprotection using polymer supported sulfonic acid. Overall, this study showcases how flow chemistry can be applied to gain benefits when faced with problems during mesoscale

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

• Franziska Klitsche,
• Julian Ramcke,
• Julia Migenda,
• Andreas Hensel,
• Tobias Vossmeyer,
• Horst Weller,
• Silvia Gross and
• Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

• catecholates on TiO2 and steel, we explored their use for the functionalization of ZnO NPs. Synthesis of tripodal catecholates A common synthetic precursor for the synthesis of suitable tripodal catecholates is the AB3-scaffold 1 [40][41][42] (Scheme 1) which is readily available in a few steps from adamantane

• an effector was prepared. This triscatecholate might be useful for the construction of diamandoid hydrophobic coatings [44] or for the reversible attachment of cyclodextrins to NPs by the formation of cyclodextrin/adamantane inclusion complexes [45]. Alternatively, acrylamide 4 and bromide 12 [42

• and sulfobetaine) or switchable hydrophobic/hydrophilic layers (reversible formation of adamantane/cyclodextrin inclusion complexes) on bulk metal surfaces or NPs. The potential of these conjugates has been demonstrated through the immobilization of the tripodal PEG-catecholate 3 on ZnO NPs and a

Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

• Thorbjørn Terndrup Nielsen,
• Catherine Amiel,
• Laurent Duroux,
• Kim Lambertsen Larsen,
• Lars Wagner Städe,
• Reinhard Wimmer and
• Véronique Wintgens

Beilstein J. Org. Chem. 2015, 11, 147–154, doi:10.3762/bjoc.11.14

• of nanoparticles. It has been shown that CD polymers can form nanoparticles when associated with various amphiphilic polymers such as dextran modified with fatty acid chains [15] or adamantane [16] in aqueous solution. Simply by mixing solutions of β-CD polymers and the hydrophobic-modified dextrans

• can be loaded with hydrophobic molecules and are stable for several days [15]. Here we report an alternative approach where instead of using biological inactive side chains, e.g., adamantane, CPT is applied. This was achieved by the synthesis of two series of novel CPT-polymers by conjugation of CPT

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

• Lisa Markenstein,
• Antje Appelt-Menzel,
• Marco Metzger and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 3087–3096, doi:10.3762/bjoc.10.325

• forms inclusion compounds with derivatives of benzene, naphthalene, adamantane, and many other moieties of similar sizes [3]. Applications of β-CD as complexing agents are limited because of low aqueous solubilities of β-CD and its complexes. Furthermore, the toxic potential of β-CD is known for a long

• much lower binding potential to sevoflurane than all other CD derivatives. Low binding affinities of TRIMEB are also known towards other guest molecules, such as tert-butyl benzoate and adamantane-1-carboxylate, and had been rationalized by the lack of intramolecular hydrogen bonds which would

Synthesis and characterization of a new photoinduced switchable β-cyclodextrin dimer

• Florian Hamon,
• Claire Blaszkiewicz,
• Marie Buchotte,
• Estelle Banaszak-Léonard,
• Hervé Bricout,
• Sébastien Tilloy,
• Eric Monflier,
• Christine Cézard,
• Laurent Bouteiller,
• Christophe Len and
• Florence Djedaini-Pilard

Beilstein J. Org. Chem. 2014, 10, 2874–2885, doi:10.3762/bjoc.10.304

• configurations, respectively. In these conditions, using azobenzene as a linker between two β-CD can lead to a modulation of the inclusion properties, such as a cooperative effect. The cavity of each CD is available to form an inclusion complex with a hydrophobic guest molecule. Among these, adamantane is known

• to be an excellent guest for the β-CD cavity, with an association constant Ka ranging from 2·104 M−1 to 4·104 M−1 [35]. This is because the adamantyl residue fits perfectly inside the β-CD cavity. In this present work, we investigated how the affinity between the dimer of adamantane and switchable

Loose-fit polypseudorotaxanes constructed from γ-CDs and PHEMA-PPG-PEG-PPG-PHEMA

• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2014, 10, 2461–2469, doi:10.3762/bjoc.10.257

• and tetramethylsilane (TMS) as an internal standard. 13C cross-polarization magic-angle spinning (CP/MAS) NMR spectra were measured on a Bruker AV 300 NMR spectrometer with a single contact time of 1 ms and a spinning rate of 5 kHz. Chemical shifts were compared to an external adamantane standard. Gel

Towards the sequence-specific multivalent molecular recognition of cyclodextrin oligomers

• Michael Kurlemann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 2428–2440, doi:10.3762/bjoc.10.253

• complementary and non-complementary strands modified with guest molecules and the investigation of their complexation behavior towards each other by isothermal titration calorimetry (ITC). As complementary binding motifs n-butyl and α-CD and adamantane and β-CD were selected. It was found that it is possible to

• realize sequence-specific molecular recognition by the use of host–guest chemistry, but the recognition motifs as well as the linkages have to be chosen very carefully. In the case of trivalent systems one adamantane moiety must be included to induce preferred formation of 1:1 adducts. Due to the too weak

• interaction between n-butyl and α-CD these systems have a negative chelate cooperativity and open adducts are preferentially formed. As soon as two adamantane moieties are present, the complementary systems have a positive chelate cooperativity and double-stranded structures are favored over open adducts. In

(CF₃CO)₂O/CF₃SO₃H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

• JungKeun Kim,
• Elvira Shokova,
• Victor Tafeenko and
• Vladimir Kovalev

Beilstein J. Org. Chem. 2014, 10, 2270–2278, doi:10.3762/bjoc.10.236

• hydroxydiketone 3x, which could be hydrolyzed to the corresponding alcohol 3y (reaction 3 in Scheme 2). The acylation of 1-indanone (2а) with 2,2’-(adamantane-1,3-diyl)diacetic acid (1l) gave the tetraketone 3z. Finally, we used our method in a two-stage one-pot syntheses of pyrazoles, which find extensive use in

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• methyl 2-(4-methoxy-4-(triethylsilylperoxy)cyclohexyl)acetate (108) with 2-methyleneadamantane (109) produced adamantane-2-spiro-3’,8’-methoxycarbonylmethyl-1’,2’-dioxaspiro[4.5]decane (110) in 40% yield (Scheme 28) [258]. The use of easily accessible triethylsilylperoxyacetals 111 as the starting

•  48) [300]. 2.5. Structural modifications, in which 1,2,4-trioxolane ring remains intact Scheme 49 shows possible modifications of substituents at the ozonide ring by the reduction of the ester group in cis-adamantane-2-spiro-3’-8’-ethoxycarbonyl-1’,2’,4’-trioxa-spiro[4.5]decane 182 to form the

• alcohol cis-adamantane-2-spiro-3’-8’-hydroxymethyl-1’,2’,4’-trioxaspiro[4.5]decane 183. The latter was mesylated to 184 (cis-adamantane-2-spiro-3’-8’-methanesulfonylmethyl-1’,2’,4’-trioxa-spiro[4.5]decane), and used in the reaction with sodium 1-methyl-1H-tetrazole-5-thiolate 185 for the synthesis of cis

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• . Results and Discussion Two cycloaliphatic thioketones that were previously studied in similar reactions with diazo compounds [14], were selected as dipolarophiles for the present study, namely 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one (1a) [15] and adamantane-2-thione (1b) [16] (Figure 1). As for the

• ; arbitrary numbering of atoms). Energy profile for the transformation of 1,3-oxathiole 3e to alkene 5e. Relative free energies (kcal·mol−1, 298 K) computed at the DFT PBE1PBE/6-31G(d) level. Reaction of diazocarbonyl compounds 2a,c,e with adamantane-2-thione (1b). Three possible pathways A, B and C for the

Flow Giese reaction using cyanoborohydride as a radical mediator

• Takahide Fukuyama,
• Takuji Kawamoto,
• Mikako Kobayashi and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2013, 9, 1791–1796, doi:10.3762/bjoc.9.208

• ) these two flow Giese reactions worked well to give the corresponding addition products 3b and 3c in 88 and 81% yield, respectively (Scheme 5). It should be noted that for these secondary and tertiary substrates, simple reduction to give octane (2b) or adamantane (2c) was hardly observed. Conclusion The

Structures of the reaction products of the AZADO radical with TCNQF₄ or thiourea

• Hideto Suzuki,
• Yuta Kawahara,
• Hiroki Akutsu,
• Jun-ichi Yamada and
• Shin’ichi Nakatsuji

Beilstein J. Org. Chem. 2013, 9, 1487–1491, doi:10.3762/bjoc.9.169

• including oxygen [1]. Sometimes, however, the merit turns out to be a drawback by limiting its properties and reactivity. For example, 1 is inefficient in the oxidation of sterically hindered secondary alcohols. The AZADO radical (2) [2] is an intriguing nitroxide radical with adamantane-like structure and

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• proceeded under 1 atmosphere of O2 alone, without any additional initiator being required. Radical initiation by redox processes Nitrogen oxides and nitric acid The PINO activation by means of nitric oxide was first reported by Ishii et al. in 1997 [22]. By reacting adamantane in a mixed solvent of

• hydroxamic acid and O2. NHPI-catalyzed reaction of adamantane under NO atmosphere. Nitration of alkanes and alkyl side-chains of aromatics. Radical mechanism for the nitration of alkanes catalyzed by NHPI. Benzyl alcohols from alkylbenzenes. Catalytic cycle of laccase-NHDs mediator oxidizing system. DADCAQ

Linkage of α-cyclodextrin-terminated poly(dimethylsiloxanes) by inclusion of quasi bifunctional ferrocene

• Helmut Ritter,
• Berit Knudsen and
• Valerij Durnev

Beilstein J. Org. Chem. 2013, 9, 1278–1284, doi:10.3762/bjoc.9.144

• attached are of increasing interest in recent years. For example, polymers bearing β-CD as side or terminal groups and their interaction with classical guest groups such as adamantane or azo-dyes have been intensively studied [1][2][3][4]. The characterization of the inclusion complexes between

Space filling of β-cyclodextrin and β-cyclodextrin derivatives by volatile hydrophobic guests

• Sophie Fourmentin,
• Anca Ciobanu,
• David Landy and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1185–1191, doi:10.3762/bjoc.9.133

• pressure; Introduction β-Cyclodextrin (β-CD, 1), the cyclic α(1→4) heptamer of glucose, is known to form inclusion compounds with a great variety of guests [1], such as derivatives of benzene [2][3], cyclohexane [4], adamantane [5][6], other alicyclic guests [7], and also inorganic molecules or ions [1][8

Superstructures of fluorescent cyclodextrin via click-reaction

• Arkadius Maciollek,
• Helmut Ritter and
• Rainer Beckert

Beilstein J. Org. Chem. 2013, 9, 827–831, doi:10.3762/bjoc.9.94

• )-interactions. The supramolecular structures were characterized by 1H NMR-ROESY spectroscopy, dynamic light scattering, UV–vis spectroscopy, fluorescence spectroscopy, and asymmetric flow field-flow fractionation. By adding potassium adamantane-1-carboxylate, the thiazol dye is displaced from the CD-cavity and

• spectroscopy and fluorescence spectroscopy. Figure 2 shows the UV–vis absorption spectra of 3 in water with the characteristic band at λmax= 340 nm. The addition of a 10-fold excess of potassium adamantane-1-carboxylate, as competitive guest for CD leads to a hypsochromic shift with λmax = 336 nm, through the

• exclusion of the fluorophore moiety from the hydrophobic cavity of CD. This exchange causes a change in the HOMO–LUMO gap [14][15]. Figure 3 shows the fluorescence spectra of 3 in aqueous solution. Upon addition of potassium adamantane-1-carboxylate the maximum wavelength changes from 417 to 442 nm and the

Influence of intramolecular hydrogen bonds on the binding potential of methylated β-cyclodextrin derivatives

• Gerhard Wenz

Beilstein J. Org. Chem. 2012, 8, 1890–1895, doi:10.3762/bjoc.8.218

• regioselective methods. Binding free energies and binding enthalpies of these hosts towards 4-tert-butylbenzoate and adamantane-1-carboxylate were determined by isothermal titration microcalorimetry (ITC). It was found that methyl substituents at the secondary positions of β-CD lead to a tremendous reduction of

• hydrophobic cavity of β-CD and therefore improve the binding potential for hydrophobic guest molecules. Up to now, only little is known about the influence of methyl substituents on the inclusion potential of β-CD [26][27]. The dimethyl derivative 2 binds adamantane derivatives with a similar binding

• pattern of methylation on the complexation of amphiphilic guests, we synthesized well-defined model compounds 2–6 (Figure 1) of methylated β-CD, using regioselective procedures already published [30]. 4-tert-Butylbenzoate and adamantane-1-carboxylate were chosen as representative guests. Complexation of

Mannose-decorated cyclodextrin vesicles: The interplay of multivalency and surface density in lectin–carbohydrate recognition

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2012, 8, 1543–1551, doi:10.3762/bjoc.8.175

• be modified by host–guest interactions with functional guest molecules. In this article, we investigate the multivalent interaction of the lectin concanavalin A (ConA) with cyclodextrin vesicles decorated with mannose–adamantane conjugates with one, two or three adamantane units as well as one or two

• multivalent interaction with ConA, and the most efficient interaction (i.e., fastest agglutination at lowest concentration) was observed for mannose–adamantane conjugates, in which both the cyclodextrin–adamantane and the lectin–mannose interaction is inherently multivalent. Keywords: carbohydrates

• and extrusion through a 0.1 μm polycarbonate membrane [27]. The cavities of each cyclodextrin are available to form inclusion complexes with hydrophobic guest molecules. Adamantane is known to be an excellent guest for β-cyclodextrin cavities (Ka = (2–3) × 104 M−1). We were able to recently

Synthesis of multivalent host and guest molecules for the construction of multithreaded diamide pseudorotaxanes

• Nora L. Löw,
• Egor V. Dzyuba,
• Boris Brusilowskij,
• Lena Kaufmann,
• Elisa Franzmann,
• Wolfgang Maison,
• Emily Brandt,
• Daniel Aicher,
• Arno Wiehe and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2012, 8, 234–245, doi:10.3762/bjoc.8.24

• multivalent axles that fit to the wheels described above, the same spacers 9, 11 and 13 were also used for the synthesis of multivalent guests 17–19, respectively (Scheme 5). In addition, a triethynyl-adamantane derivative 20 [109][110] was employed in order to prepare an axle component with a slightly

Hyperbranched polyethylenimine bearing cyclodextrin moieties showing temperature and pH controlled dye release

• Indra Böhm,
• Susanne Katharina Kreth and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1130–1134, doi:10.3762/bjoc.7.130

• exploited to complex various hydrophobic guests such as proteins, dyes and anti tumor drugs [17][18][19][20][21][22]. Inclusion complexes with, e.g., adamantane derivates, are relatively stable due to their high binding constants [23][24]. These kinds of supramolecular complexes become less stable under

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• '-dimethoxybiphenyl-2,2'-diamine was treated with adamantane-2-carbonyl chloride in the presence of Et3N at room temperature (25 °C) in DCM to afford the corresponding amide (S)-1c in 71% yield. According to the synthetic method for the synthesis of compound (S)-6a, NHC–Au complex (S)-6c was successfully prepared in

Photoinduced homolytic C–H activation in N-(4-homoadamantyl)phthalimide

• Nikola Cindro,
• Margareta Horvat,
• Kata Mlinarić-Majerski,
• Axel G. Griesbeck and
• Nikola Basarić

Beilstein J. Org. Chem. 2011, 7, 270–277, doi:10.3762/bjoc.7.36

• was conducted to investigate the availability of different C–H bonds in the homoadamantane skeleton for the homolytic activation, that is, abstraction by the phthalimide. The research was, furthermore, sparked by the discovery that numerous poly-azaheterocyclic adamantane derivatives show antiviral

Calix[4]arene-click-cyclodextrin and supramolecular structures with watersoluble NIPAAM-copolymers bearing adamantyl units: “Rings on ring on chain”

• Bernd Garska,
• Monir Tabatabai and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 784–788, doi:10.3762/bjoc.6.83

• intermolecular electrostatic repulsion. Accordingly, the hydrodynamic diameter of 4 decreased in NaOH solution from 150 nm to 9.0 nm, which can actually be attributed to the existence of trimers. Host–guest complexion of 4 and 5 An adamantane containing copolymer 5 was prepared via free radical polymerization of

• 6-acrylamido-N-adamantyl-hexane amide and NIPAAM. Copolymer 5 was mixed with 4 subsequently (Scheme 2) to form supermolecular structures. The hydrodynamic diameter of copolymer 5 increased from 8.5 nm to 53 nm after addition of 4. This clearly indicates the inclusion of a polymer attached adamantane

• moiety into the cavity of CD. The adamantane moiety is known to be one of the best guest molecules for β-CD [15]. A relatively high complex stability constant for a polymer attached adamantane groups with CD is about 5000 M−1 [16]. Therefore, as shown in Scheme 2, compound 4 obviously is expected to act