The design and synthesis of an antibacterial phenothiazine–siderophore conjugate

• Abed Tarapdar,
• James K. S. Norris,
• Oliver Sampson,
• Galina Mukamolova and
• James T. Hodgkinson

Beilstein J. Org. Chem. 2018, 14, 2646–2650, doi:10.3762/bjoc.14.242

• . However, as our final conjugate contains an aromatic halide we wanted to avoid hydrogenation as the final step and we instead chose to use the para-methoxybenzyl (PMB) protecting group which can be removed under acidic conditions. PMB-protected benzoic acid building block 7 was prepared following a

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• electrochemical reduction. In addition, the corrin-ring of the B12 derivatives is tolerant to free radicals, as described above. Thus, alkylated complexes have been used for radical-mediated organic synthesis such as halide coupling, alkene coupling, and addition to double bonds [7][26][27]. In particular, the Co

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• trituration. The reaction is tolerant to halide substitution at the 6-, 7-, and 8-positions (9b, 9c, 9f, 9h). The unprotected hydroxy group in 9d gave reasonably high yield as did electron-withdrawing nitro groups in the 6- and 7-positions (9e, 9g). The substituted isatoic anhydrides from Scheme 3 were then

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• generated by Lewis acid-promoted halide abstraction from imidoyl chlorides or by alkylation of nitriles. A nucleophilic attack on such species followed by cyclization provides access to a variety of heterocycles. Intramolecular reactions of in situ generated nitrilium ions leading to heterocyclic compounds

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

• as described by Thordarson [23][24]. Table 1 shows the measured apparent binding or association constants, from which two trends can be discerned: Firstly, the Kassoc values with the tetra-n-butylammonium halide salts show a trend that is in the order Cl− > Br− > I−. This trend is similar to that

• with the empirical dispersion correction was used with the standard 6-31G(d) basis set [26]. We had previously described the use of this system in our previous studies in particular, in reference [20] as being more reliable than the use of B3LYP/6-31G(d) with our systems. Furthermore, for the halide

• are shown in Table 1. No easily discernable significant correlation between the interaction energies and the experimentally measured binding constants can be discerned for the three halide salt complexes; the highest IE (−337.805 kJ mol−1) was found for the chloride which also had the highest binding

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• the corresponding products, which were isolated as methyl esters (Scheme 8). Thus, compound 7 bearing alkyl, ether, ester, and halide substituents exhibited good reactivity. Cinnamonitrile afforded 8f-Me in 81% yield using 10 mol % of catalyst. α-Phenyl-substituted α,β-unsaturated nitrile also reacted

Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands

• Anthony Wishard and
• Bruce C. Gibb

Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195

• Anthony Wishard Bruce C. Gibb Department of Chemistry, Tulane University, New Orleans, LA 70118, USA 10.3762/bjoc.14.195 Abstract Although alkali halide salts play key roles in all living systems, the physical models used to describe the properties of aqueous solutions of salts do not take into

• titration with various halide salts. The fifteen salts studied were a matrix of the alkali metal cations Li+, Na+, K+, and Cs+ in combination with the halides F− through I−, the one omission being poorly soluble lithium fluoride (maximum solubility = 0.134 g mL−1). Unsurprisingly, given the pKa values of

• ignored. An obvious trend in the data for host 2 (Figure 3) is how the nature of the halide affects aggregation. Over all concentrations of F− salts the hydrodynamic diameter of the host was anomalously small, with maximum diameters measured in the presence of NaF, KF, and CsF being 1.6, 1.9, and 1.8 nm

Bi-mediated allylation of aldehydes in [bmim][Br]: a mechanistic investigation

• Mrunesh Koli,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2018, 14, 2198–2203, doi:10.3762/bjoc.14.193

• the powder XRD analysis of the light yellow precipitate. Earlier, it has been reported [38][43] that the organobismuth halide generated in situ may act as a Lewis acid activator for the faster production of linear homoallylic alcohols. In the present case also, such a mechanism cannot be excluded

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• equivalents of a strong base such as CsOH yields quantitatively the corresponding cesium thiolates B and D which are quite stable under standard Schlenk conditions. Addition of an alkyl halide can attach a broad range of different substituents. The cyanoethyl group allows a sequential deprotection and

Evaluation of dispersion type metal···π arene interaction in arylbismuth compounds – an experimental and theoretical study

• Ana-Maria Preda,
• Małgorzata Krasowska,
• Lydia Wrobel,
• Philipp Kitschke,
• Phil C. Andrews,
• Jonathan G. MacLellan,
• Lutz Mertens,
• Marcus Korb,
• Tobias Rüffer,
• Heinrich Lang,
• Alexander A. Auer and
• Michael Mehring

Beilstein J. Org. Chem. 2018, 14, 2125–2145, doi:10.3762/bjoc.14.187

• , compounds of the type Ar2BiX (Ar = C6H3-t-Bu2-3,5, X = halide) show some special features. In these compounds the formation of a one dimensional ribbon as a result of Bi···X···Bi coordination is typical, which is supplemented by Bi···π arene interactions between two neighboring bismuth atoms in the chain

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• Cl− counter ion) were unsuccessful since the reaction of the SNS pincer ligand 19a with PdCl2(MeCN)2 led to the formation of N,S-Pd(II) 20a presumably due to the weak basicity of the sulfur atom. Gratifyingly, the problem was solved by treatment of the reaction mixture with the halide abstractor

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• ratio. The latter was expected to be formed by halide counter ion exchange between CTAB and KI. Since the reaction occurred as expected, it was applied to the synthesis of amino acid conjugates. Acetyl groups of the (diacetoxyiodo)benzene were exchanged with N- and O-protected amino acids by slow

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• halofunctionalizations of acyclic monoterpenoids were performed using a combination of a hypervalent iodine(III) reagent and a halide salt. In this manner, the dibromination, the bromo(trifluoro)acetoxylation, the bromohydroxylation, the iodo(trifluoro)acetoxylation or the ene-type chlorination of the distal

• suitable halide salt. In particular, the chemoselectivity of the reaction can be finely tuned by adjusting several parameters, such as the nature of the halide as well as of the iodine(III) ligands and the halide counterion [15][16]. In the case of polyprenoids, we mostly devoted our efforts to achieve the

• experiments Considering the differences and similarities in the outcome of the various reaction conditions, a common mechanism with a central divergence point can be proposed. First, the diacetoxyiodobenzene reagent 7 would undergo ligand exchange with the halide to give mixed hypervalent iodine(III) 8

Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

• Toshifumi Dohi,
• Shohei Ueda,
• Kosuke Iwasaki,
• Yusuke Tsunoda,
• Koji Morimoto and
• Yasuyuki Kita

Beilstein J. Org. Chem. 2018, 14, 1087–1094, doi:10.3762/bjoc.14.94

• intermediate (path A). Alternatively, the benzyl radical formed in situ couples with the iodanyl radical to give the pseudo halide, benzyl-λ3-iodane, which is more reactive to nucleophilic substitution by a carboxylic acid [77][78]. Another possible course of the reaction mechanism assumes the formation of a

Hypervalent iodine-mediated Ritter-type amidation of terminal alkenes: The synthesis of isoxazoline and pyrazoline cores

• Sang Won Park,
• Soong-Hyun Kim,
• Jaeyoung Song,
• Ga Young Park,
• Darong Kim,
• Tae-Gyu Nam and
• Ki Bum Hong

Beilstein J. Org. Chem. 2018, 14, 1028–1033, doi:10.3762/bjoc.14.89

• [23][24][25][26][27]. Results and Discussion As depicted in Scheme 1, we have previously reported an inter-/intramolecular alkene diamination using either N-iodosuccinimide (NIS) or a phenyliodine diacetate (PIDA)/halide additive combination [28][29][30]. Vinylanilines and vinylaminopyridines in

The first Pd-catalyzed Buchwald–Hartwig aminations at C-2 or C-4 in the estrone series

• Ildikó Bacsa,
• Dávid Szemerédi,
• János Wölfling,
• Gyula Schneider,
• Lilla Fekete and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 998–1003, doi:10.3762/bjoc.14.85

• under microwave irradiation or thermal heating. The solvent was selected on the basis of literature data reported for other Pd-catalyzed reactions of estrone derivatives [18][20]. The pre-stirring of the reaction mixture without adding the aryl halide 1 was carried out at 60 °C for 5 min in a water bath

• , then aryl halide 1 was added and the mixture was irradiated in a microwave reactor at 150 °C for 10 min. The outcome of the couplings greatly depended on the nature of the Pd source, the ligand and the base. As summarized in Table 1, reactions with pre-catalyst Pd(OAc)2 gave the desired aminoestrone 5

• in low to high yields (Table 1, entries 1, 2, 4, 7–9) except when using Cs2CO3 as the base (Table 1, entries 6 and 10). In the latter cases only dehalogenation of the starting aryl halide was observed in around 20–60% yield. The use of KOt-Bu (Table 1, entries 2 and 8) or NaOt-Bu (Table 1, entries 4

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• . However, this pathway is shut down under solvent-free conditions, making everything in the system a contact ion pair. The traditional solution-based mechanism of the Wittig reaction proceeds via a four-membered oxaphosphetane intermediate. However, by incorporating the halide anion and the alkali metal

• cation into the mechanism, a six-membered ring, similar to that proposed in Scheme 2, would result (Figure 3). Based on this hypothesis, in addition to the oxygen and phosphorous forming a stable bond, the alkali metal and halide must form a stable contact ion pair as well. These interactions and the

• alkali metal and halide pairs would be most favourable. For example, bromide is a borderline soft anion, so based on the proposed mechanism we would expect more product to form if the counter ion is Cs+(soft) than if it was Li+ (hard). Using the Jones–Dole viscosity B coefficient, we could also predict

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• donating as well as electron withdrawing functional groups, as coupling partners (Scheme 1). Concerning the targeted synthesis of 1, aryl halide 4e was of special interest as the cyano group is known to be convertible to the ortho-tetrazole moiety [9] present in the API. Based on prior optimisation studies

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

• Thaís A. Rossa,
• Nícolas S. Suveges,
• Marcus M. Sá,
• David Cantillo and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2018, 14, 506–514, doi:10.3762/bjoc.14.36

• ][31][32]. Recently, Patil and Luzzio reported the preparation of a wide range of 2-substituted derivatives 7 by a simple nucleophilic halide displacement from 2-chloromethyl-4,5-diaryloxazoles, illustrating their usefulness (Scheme 2) [33]. In a related work, Luzzio et al. described the synthesis of

• ]. Important drawbacks observed in the generation of compounds of type 7 include the instability of the halide intermediate 6, which might be difficult to isolate due decomposition reactions, as well as selectivity issues during the generation of the oxazole ring. It has been shown that problems associated

• intermediate is then reacted with a 2-haloacyl halide at room temperature, to form the 2-(halomethyl)oxazole moiety. Subsequent reaction with an aqueous stream containing NaN3 then leads to the formation of the desired 2-(azidomethyl)oxazole. The optimization of each reaction step and the integration to a

Functionalization of N-arylglycine esters: electrocatalytic access to C–C bonds mediated by n-Bu₄NI

• Mi-Hai Luo,
• Yang-Ye Jiang,
• Kun Xu,
• Yong-Guo Liu,
• Bao-Guo Sun and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2018, 14, 499–505, doi:10.3762/bjoc.14.35

• be an environmentally benign method to achieve the formation of a new chemical bond and a functional group conversion by using electrons as redox reagent rather than terminal chemicals [20][21][22][23][24][25][26][27]. In this context, we have applied simple halide ions as redox catalysts to achieve

• ). Investigation of the anode proved that graphite was superior to Pt and DSA (Dimensionally Stable Anode, Table 1, entries 14 and 15). Finally, to further improve the reaction efficiency, several halide-containing mediators as redox catalyst were evaluated. To our delight, when n-Bu4NI was utilized as a redox

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• ). However, it was found that the generation of the trifluoromethyl anion proceeds faster than the subsequent transfer of CF3 to the aromatic halide. Subsequently, the problem was solved by using a slow addition mode that adjusted the rate of decarboxylation step to the rate of the consumption of CF3 in the

• groups. This reaction can tolerate a variety of functionalities, such as alkoxy, amino and halide groups. The author proposed a plausible mechanism depicted in Scheme 42. At first, a dinitrogen ligated complex (N,N)CuX A is generated in situ by the reaction of CuI with phen. Then, a copper(I)-acetylide

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• photoexcited state of [IrIII] to [IrII] and forms a thiyl radical. Next, the [IrIII] is regenerated by single-electron reduction of the aryl halide, delivering an aryl halide radical anion. Radical addition to the aromatic thiolate anion forms a sulfide radical anion intermediate, which is oxidized by the

• base and DMSO as solvent they observed a colouring of the reaction mixture, whereas the reagents are colourless themselves. They suggest that the thiol becomes deprotonated to the respective thiolate anion and subsequently an electron donor–acceptor complex with the aryl halide is formed. Irradiation

• with white light then triggers a light-induced electron transfer from the anion to the aryl halide, releasing the halide as an anion and resulting in a thiyl radical and an aryl radical. Finally, radical–radical cross-coupling yields the respective diaryl sulfide. Ammonium thiocyanate Formation of

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• Wehman (Scheme 4) [10]. Vinylphosphonium salts can also be prepared by alkylation of phosphines (usually triphenylphosphine) with allyl halide derivatives and isomerization of allylphosphonium salts 4 thus obtained under the influence of bases such as triethylamine or sodium carbonate (Scheme 5) [11][12

• phosphorus ylides from vinylphosphonium salts. Intramolecular Wittig reaction with the use of vinylphosphonium salts. Alkylation of diphenylvinylphosphine with methyl or benzyl iodide. Methylation of isopropenyldiphenylphosphine with methyl iodide. Alkylation of phosphines with allyl halide derivatives and

Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

• Paweł Chmielarz,
• Tomasz Pacześniak,
• Katarzyna Rydel-Ciszek,
• Izabela Zaborniak,
• Paulina Biedka and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2017, 13, 2466–2472, doi:10.3762/bjoc.13.243

• . As expected, addition of an alkyl halide initiator to a solution of CuIIBr2/TPMA during the voltammetric measurements causes a loss of reversibility and an increase of the cathodic current because of reduction of the regenerated CuIIBr2/TPMA via the catalytic electrochemical catalytic process (EC

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

• Matthias Wünsch,
• David Schröder,
• Tanja Fröhr,
• Lisa Teichmann,
• Sebastian Hedwig,
• Nils Janson,
• Clara Belu,
• Jasmin Simon,
• Shari Heidemeyer,
• Philipp Holtkamp,
• Jens Rudlof,
• Lennard Klemme,
• Alessa Hinzmann,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240

• to avoid nucleophilic substitution of the halide at a late stage, we decided to start the synthesis with 4-azidobutanal, which was prepared by opening THF with iodine and NaBH4, nucleophilic substitution by sodium azide and Swern oxidation of the alcohol. 4-Azidobutanal was converted with chiral