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

• refluxing α-amino acid phenylhydrazides with levulinic acid in toluene led to the corresponding dihydro-1H-pyrrolo[1,2-a]imidazole-2,5-diones. These authors explained clearly the behavior of the solvent and its influence in the reaction. In addition, substituted 1-hydroxy-1H-imidazo[2,1-a]isoindole-2,5(3H

The influence of the cationic carbenes on the initiation kinetics of ruthenium-based metathesis catalysts; a DFT study

• Magdalena Jawiczuk,
• Angelika Janaszkiewicz and
• Bartosz Trzaskowski

Beilstein J. Org. Chem. 2018, 14, 2872–2880, doi:10.3762/bjoc.14.266

• stable in water and, therefore, environmentally-friendly. The idea of incorporating a quaternary ammonium moiety into the imidazole part of the carbene was later expanded by several other groups, including a number of new water-soluble catalysts synthesized by Skowerski et al. [23][24]. In the meantime

• affect the efficiency of the catalyst in model metathesis reactions in comparison to Skowerski’s complexes with only one –CH2– unit. Curiously, carbenes with the cationic group even closer to the imidazole moiety (with no spacer) or incorporated into the imidazole core have been synthesized only very

• recently and examples of their transition metal complexes are scarce. In 2013 Ganter described a cationic NHC with a fused pyridinium moiety and the formal +1 charge just one bond away from the imidazole core [27]. In 2017 César synthesized a cationic imidazolylidene NHC with an ammonium tag attached

Synthesis of pyrrolidine-based hamamelitannin analogues as quorum sensing inhibitors in Staphylococcus aureus

• Jakob Bouton,
• Kristof Van Hecke,
• Reuven Rasooly and
• Serge Van Calenbergh

Beilstein J. Org. Chem. 2018, 14, 2822–2828, doi:10.3762/bjoc.14.260

• ) 5 mol % Grubbs–Hoveyda II, 1,2-DCE, 50 °C. Synthesis of alternative eastern fragment 23. Reagents and conditions: a) TBSCl, imidazole, CH2Cl2, rt; b) H2NNH2·H2O, MeOH, reflux; c) p-Ns-Cl, Et3N, CH2Cl2, 0 °C. Synthesis of 4. Reagents and conditions: a) PPh3, DEAD, THF, 0 °C to rt; b) Grubbs–Hoveyda

Synthesis of α-D-GalpN₃-(1-3)-D-GalpN₃: α- and 3-O-selectivity using 3,4-diol acceptors

• Emil Glibstrup and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2018, 14, 2805–2811, doi:10.3762/bjoc.14.258

• from the common 2-azidoglucose precursor 7, the 4,6-O-benzylidene group was removed with TsOH to give the 4,6-diol in 95% yield, followed by selective 6-O-protection using TBDPS-Cl and imidazole (IM) in 90% yield. The 4,6-O-benzylidene motif could also be regioselectively opened using triethylsilane

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• , triazolo[1,2-a]indazoletrione derivatives, tetrasubstituted imidazole derivatives, aromatic/aliphatic sulfide derivatives, and N-substituted pyrrole derivatives. These catalysts were used in cellulose hydrolysis, cellobiose hydrolysis, production of fatty acid ethyl ester, the transesterification of

• 2,2'-bipyridine 25 using the reaction of chlorosulfonic acid and 2,2'-bipyridine as well as its application for the synthesis of the various xanthene derivatives 24, 27, and 28 [41]. In another study, the sulfonated imidazole 26 was prepared via the dropwise addition of chlorosulfonic acid to a

• stirred solution of imidazole in dry CH2Cl2 in an ice bath. In the next step, sulfuric acid 98% was added dropwise to the reaction mixture containing the sulfonated imidazole at room temperature to obtain 1,3-disulfo-1H-imidazolium hydrogen sulfate [Dsim]HSO4 (26) as a viscous pale yellow oil catalyst

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• interactions in the intermediate phase between the catalyst chlorine and the substrate may be responsible for the accomplishments of the reactions, which were deeply investigated and discussed in the literature [33][34][35][36][37] and see references therein. In our case it was observed that the imidazole

Transition metal-free oxidative and deoxygenative C–H/C–Li cross-couplings of 2H-imidazole 1-oxides with carboranyl lithium as an efficient synthetic approach to azaheterocyclic carboranes

• Lidia A. Smyshliaeva,
• Mikhail V. Varaksin,
• Pavel A. Slepukhin,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2018, 14, 2618–2626, doi:10.3762/bjoc.14.240

• 10.3762/bjoc.14.240 Abstract The direct C–H functionalization methodology has first been applied to perform transition metal-free C–H/C–Li cross-couplings of 2H-imidazole 1-oxides with carboranyllithium. This atom- and step-economical approach, based on one-pot reactions of nucleophilic substitution of

• hydrogen (SNH) in non-aromatic azaheterocycles, affords novel imidazolyl-modified carboranes of two types (N-oxides and their deoxygenative analogues), which are particularly of interest in the design of advanced materials. Keywords: carboranes; C–H functionalization; C–H/C–Li cross-coupling; 2H-imidazole

• reactions to functionalize non-aromatic heterocycles. In particular, only few examples of SNH reactions are available in the chemistry of 2H-imidazole 1-oxides [57][58][59][60] that are of interest as promising pharmacoactive azaheterocyclic compounds [61][62][63][64][65]. In this paper, we wish to report

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• magnesium enolate of malonic acid half ester, prepared in situ from potassium methyl malonate, MgCl2 and triethylamine in acetonitrile, was added [24][25]. The acylation of magnesium methyl malonate by the preformed imidazole 3 led to the desired bifunctional starting material 4 in good yield (79

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• ) Red-Al, anh. Et2O, −20 °C, 8 h, 95%; (c) (i) DMSO, CH2Cl2, (COCl)2, −78 °C, (ii) TMS-C≡CH, n-BuLi, THF, −78 °C to rt, 3 h, 89%; (d) K2CO3, MeOH, 0 °C to rt, 1 h, 92%; (e) TBSCl, imidazole, 0 °C to rt, 1 h, 98%; (f) I2, TPP, imidazole, 0 °C to rt, 1 h, 92%. Stereoselective synthesis of (R)-25. Reagents

• and conditions: (a) CuCl, NH2OH·HCl, 30% n-BuNH2, Et2O, 1 h, 68%; (b) DMP, CH2Cl2, 0 °C to rt, 1 h, 87%; (c) (S)-CBS catalyst, BH3·DMS, THF, −50 °C, 16 h, 85%. Synthesis of strongylodiol H (9). Reagents and conditions: (a) TBDPSCl, imidazole, CH2Cl2, 0 °C to rt, 2 h, 95%; (b) PPTS, MeOH, 0 °C to rt, 2

• ) TBDPSCl, imidazole, CH2Cl2, 0 °C to rt, 1 h, 96%; (ii) PPTS, MeOH, 0 °C to rt, 2 h, 87%; (iii) IBX, DMSO/THF 1:1, 0 °C to rt, 1 h, 98%; (b) 16, n-BuLi, THF, −78 °C to rt, 2 h, 81%; (c) TBAF, THF, 0 °C to rt, 2 h, 82%. Comparison of 1H and 13C NMR data of strongylodiol H (isolated natural product vs

Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO₂ fixation by N-benzyl cyclic guanidine under dry and wet conditions

• Yoshiaki Yoshida,
• Naoto Aoyagi and
• Takeshi Endo

Beilstein J. Org. Chem. 2018, 14, 2204–2211, doi:10.3762/bjoc.14.194

• was estimated by using DFT calculation with B3LYP/6-31G* method (Wavefunction, Inc., Spartan’06 Windows version 1.1.0) [41]. Synthesis of N-benzyl cyclic guanidine 2-Benzylamino-4,5-dihydro-1H-imidazole (N-benzyl cyclic guanidine, 1) was synthesized according to the literature [42]. mp 79.9–83.1 °C

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

•  1, entry 16). In addition, as previously reported in case of crotylation [40], the allylation did not proceed in absence of oxygen (Table 1, entry 17), or when the C-2 imidazole proton was absent in the RTIL (in 1-butyl-2,3-dimethylimidazolium bromide ([bmmim][Br]), Table 1, entry 18). This result

Chiral bisoxazoline ligands designed to stabilize bimetallic complexes

• Deepankar Das,
• Rudrajit Mal,
• Nisha Mittal,
• Zhengbo Zhu,
• Thomas J. Emge and
• Daniel Seidel

Beilstein J. Org. Chem. 2018, 14, 2002–2011, doi:10.3762/bjoc.14.175

• instance, treatment of 6 with two equivalents of copper perchlorate hexahydrate led to the formation of a bis-copper complex [49][50]. The two Cu(ΙΙ) ions, which have a Cu∙∙∙Cu distance of 2.947 Å, are coordinated to the pentadentate bisoxazoline-imidazole moiety and are bridged by the central phenoxy

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• -introduced into the catalytic cycle. Several copper salts (CuCl, CuCl2, CuOAc and Cu(OAc)2) were evaluated as part of optimizing the reaction conditions and they all provided poor yields. 3.3.3 Acetoxysulfenylation of Baylis–Hillman alcohols. Yadav and Aswathi reported a regioselective CuI-imidazole

Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA

• Timo Weinrich,
• Eva A. Jaumann,
• Ute M. Scheffer,
• Thomas F. Prisner and
• Michael W. Göbel

Beilstein J. Org. Chem. 2018, 14, 1563–1569, doi:10.3762/bjoc.14.133

• , Et3N, CH2Cl2, rt, 4.5 h. Synthesis of phosphoramidite 8. Reagents and conditions: (a) Addition of 10, diisopropylethylamine, 1-propanol, 75 °C, 7 h, rt, 14 h; (b) 7 N NH3 in MeOH, 0 °C → rt, 3 h; (c) dimethoxytrityl chloride, pyridine, rt, 20 h; (d) tert-butyldimethylsilyl chloride, imidazole, DMF, rt

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• significant antibacterial activity against Gram-positive bacterial strains [50]. Several other distamycin analogs were synthesized by replacing one or more pyrrole rings with other heterocycles such as pyrazoles [51], benzofurans [52], thiazoles, thiophenes, imidazole and oxazoles [53] in order to establish a

• possess the ideal crescent shape required to wrap around the minor groove of DNA, which limit their efficacy to recognize longer stretches of DNA sequence. In order to achieve better sequence specificity, a series of oligomeric “hairpin (HP)” polyamides containing pyrrole and imidazole ring systems (Py/Im

• ) were designed and synthesized by Dervan et al. and followed by other groups. It was observed that pyrrole/imidazole polyamides were able to bind side-by-side in the minor groove of DNA with high affinity and in a sequence-specific manner. Crystal structure studies confirmed the existence of a hydrogen

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• respect to the parent drug, e.g., temozolomide converted to 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC) [9]. 4) Excretion is the final step and is responsible for the removal of the parent drug and/or its metabolites from the human body. Renal excretion is the predominant route of elimination

Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• rate. High buffer concentration has to be used and this makes elimination of salt and co-solute effects difficult. Since histidine residues are known to play a central role in the catalytic center of RNase A [58], one of the most extensively studied protein nucleases, catalysis by imidazole/imidazolium

• interesting feature of the mechanism is that both the formation and breakdown of the phosphorane intermediate proceed through a minor ionic form in a pre-equilibrium mixture. The mole fraction of neutral phosphodiester, for example, is in imidazole buffers of the order of 10−6 (pKa of phosphodiester ≈ 1

• departure of the 5´-linked nucleoside by a factor of 107. The mechanistic proposal has partly been based on Breslow’s studies on hydrolysis of 4-tert-butylcatechol cyclic phosphate by regioisomers of β-cyclodextrins bearing two imidazole groups [60]. This reverse reaction of the cyclization of 4-tert

Enzyme-free genetic copying of DNA and RNA sequences

• Marilyne Sosson and
• Clemens Richert

Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47

• neutral pH, i.e., conditions favoring longevity for this type of activated monomer, which requires protonation of the imidazole ring to be turned it into a good leaving group. Binding equilibria As mentioned above, primer extension involves the binding of the incoming nucleotide to the primer–template

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

• Fabio Tonin and
• Isabel W. C. E. Arends

Beilstein J. Org. Chem. 2018, 14, 470–483, doi:10.3762/bjoc.14.33

• ] (yield 90%) and subsequently reduced with metallic sodium in presence of imidazole and 1-propanol (yield 80%) yielding the 7β-OH epimer (UDCA) as imidazole salt. Notably, the regiospecific oxidoreduction of the 7α-OH group is achieved using weak oxidants: this behavior can be explained by the peculiar

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• 5 hours for T13-based OLEDs. A comparison established with an iridium complex, i.e., tris[1-(2,4-diisopropyldibenzo[b,d]furan-3-yl)-2-phenyl-1H-imidazole]iridium(III) (Ir(dbi)3) evidenced the relevance of the TADF approach, as a device lifetime of only 18 hours was found while operating OLEDs in the

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• -trifluoromethyloxadiazole substituent was not a viable substrate (Table 1, entry 10). Because of a similar result obtained with the N-methylimidazole substituted compound 7k, the difference between 7i and 7j could be explained by the imidazole-like structure of the 5-trifluoromethyloxadiazole moiety. The reduced inductive

• effect of the amine might be attributed to the resonance structures of imidazole (Table 1, entry 11) [72]. To determine the influence of substituents on the phenyl group, various arene(methyl)sulfanes 7l–p were tested (Table 1, entries 12–16,). Simple phenyl and electron-donating compounds 7l and 7m did

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

• photoredox-generated thiocyanate radical can add to the heteroaromatic system, which subsequently rearomatizes via deprotonation. This method was suitable for substituted imidazoheterocycles, bearing electron-donating and withdrawing groups. Other imidazole derivatives were unreactive under the reported

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations

• Aymen Skhiri,
• Ridha Ben Salem,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2017, 13, 2862–2868, doi:10.3762/bjoc.13.278

• allowed the coupling of several heteroaromatics such as thiazole, pyrrole, furan or imidazole derivatives with aryl bromides [36]. 2-Bromoselenophene, which was easily prepared by reaction of selenophene with N-bromosuccinimide [37], and 2-ethyl-4-methylthiazole were employed as model substrates for our

Nucleophilic dearomatization of 4-aza-6-nitrobenzofuroxan by CH acids in the synthesis of pharmacology-oriented compounds

• Alexey M. Starosotnikov,
• Dmitry V. Shkaev,
• Maxim A. Bastrakov,
• Ivan V. Fedyanin,
• Svyatoslav A. Shevelev and
• Igor L. Dalinger

Beilstein J. Org. Chem. 2017, 13, 2854–2861, doi:10.3762/bjoc.13.277

• to proceed depending on the structure of the substrate and the nucleophile. The first, Beirut reaction [1][2][3][4][5][6][7][8][9][10], allowing to transform the furoxan ring to pyrazine or imidazole N-oxides as well as N-hydroxyimidazole occurs under the action of α-unsubstituted aldehydes, ketones