Synthesis of acylhydrazino-peptomers, a new class of peptidomimetics, by consecutive Ugi and hydrazino-Ugi reactions

• Angélica de Fátima S. Barreto,
• Veronica Alves dos Santos and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2016, 12, 2865–2872, doi:10.3762/bjoc.12.285

• structures have also been carried out to obtain the less common but also biologically active azapeptoids [40], hydrazino-azapeptoids [41][42], retro hydrazino-azapeptoids [43] and peptoid-azapeptoid hybrids [39]. Recently, Seo et al. [44] reported the synthesis of a library of peptide-peptoid hybrid (termed

• difficult sequences [48]. It is therefore important to have alternative methods for the fast and easy construction of such important compounds. In this sense, the Ugi four-component reaction (U-4CR) has proven to be a robust and versatile method for the synthesis of peptoids and peptide-peptoid hybrids

Sydnone C-4 heteroarylation with an indolizine ring via Chichibabin indolizine synthesis

• Florin Albota,
• Mino R. Caira,
• Constantin Draghici,
• Florea Dumitrascu and
• Denisa E. Dumitrescu

Beilstein J. Org. Chem. 2016, 12, 2503–2510, doi:10.3762/bjoc.12.245

• with substituents in both rings and has the advantage over cross-coupling reactions insofar as it overcomes side reactions and uses inexpensive materials. The structures of the new sydnone-indolizine hybrids produced by the Chichibabin synthesis were confirmed by elemental analysis, NMR and IR

• bihetaryls 9 can also serve as starting materials for the generation of sydnone-pyridinium N-ylides 10 (Scheme 2) in the presence of acetylenic dipolarophiles, to form sydnone-indolizine hybrids 12. In the new compounds 12 (Scheme 2) the indolizine moiety is connected by a keto group to C-4 of the sydnone

• pyridinium salts used in the synthesis of sydnone-indolizine hybrids could be transformed into sydnone-indolizines connected via a keto group. The transformation was achieved by a one-pot procedure implying the in situ generation of sydnone-pyridinium N-ylides followed by 1,3-dipolar cycloaddition reaction

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• to form self-assembled monolayers on gold [69][70][71] as well as on zinc and iron oxide surfaces [72]. Conceptually, thienyl-bridged oligophenothiazines can be considered as a novel type of structurally well-defined electron-rich oligophenothiazine–thiophene hybrids (Figure 1). Thereby, the strong

• , 4.53; HPLC (n-hexane/THF 99.5:0.5) tR [min] (%) = 2.92 (99). Thienyl-bridged oligophenothiazines as topological hybrids of (oligo)phenothiazines and 2,5-di(hetero)aryl substituted thiophene. Cyclic voltammograms of compounds 3 (recorded in CH2Cl2, T = 293 K, electrolyte n-Bu4N+PF6−, Pt working

Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2016, 12, 1877–1883, doi:10.3762/bjoc.12.177

• allyl groups and oxa-bowl/propellane hybrids. Since non-flattened molecules are implicated in biological systems, our results would be useful in drug design [42]. Retrosynthetic approach to propellane derivatives. The molecular structure of 1a, with displacement ellipsoids drawn at the 50% probability

Ring-whizzing in polyene-PtL₂ complexes revisited

• Oluwakemi A. Oloba-Whenu,
• Thomas A. Albright and
• Chirine Soubra-Ghaoui

Beilstein J. Org. Chem. 2016, 12, 1410–1420, doi:10.3762/bjoc.12.135

• . An easy way to view these results is to take a linear combination of b2 (5) and a1 (6). This will generate two equivalent dsp hybrids. One will be filled and can interact with one component of the e1g LUMO, 21, in Figure 6 and the other will remain empty, 22. Another highly fluxional molecule is

Marine-derived myxobacteria of the suborder Nannocystineae: An underexplored source of structurally intriguing and biologically active metabolites

• Antonio Dávila-Céspedes,
• Peter Hufendiek,
• Max Crüsemann,
• Till F. Schäberle and
• Gabriele M. König

Beilstein J. Org. Chem. 2016, 12, 969–984, doi:10.3762/bjoc.12.96

• -date-explored members of these halophilic or halotolerant myxobacteria are all grouped into the suborder Nannocystineae. Few of them were chemically investigated revealing around 11 structural types belonging to the polyketide, non-ribosomal peptide, hybrids thereof or terpenoid class of secondary

• metabolites can be found in various detailed reports [19][20][21][22][23]. The majority of these metabolites are either non-ribosomal peptides, e.g., cystobactamids 1–3 (Figure 1) [24], polyketides, e.g., aurafuron A (4) [25], or hybrids thereof, e.g., corallopyronin A (5, Figure 2) [26]. Interestingly, an

• = 50 nM). So far, no genome sequence is publicly available for halotolerant strains of this genus. The only sequence found in the databases belongs to the terrestrial N. exedens ATCC 25963 (see Table 1). Remarkably, this genome encodes, among a considerable number of NRPS/PKS hybrids, 10 different

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• recognition have been performed [27]. We prepared heptakis(6-O-TBDMS-2,3-O-methyl)-β-CDs with a second CD unit in the 2 position or a (R)-Mosher acid moiety [28]. Preparation of second generation CD derivatives: dimers, and CD hybrids Bis-CDs and their metal complexes have been extensively studied as

• in Scheme 10: CD-acryloyl derivative [60][61], β-CD/dye derivatives [31][62][63][64], CD-ionic liquid hybrids [65][66], CD-based iminosugar conjugates [67], water-soluble CD homo- and heterodimers [68][69], trimers [70][71] and oligomers [72] of α-, β- and γ-CD have all been successfully produced

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• classes including polyketides, non-ribosomal peptides, their hybrids, terpenoids, and aromatic compounds formed via the shikimate pathway. The text does not aim at a comprehensive overview, but instead a selection of recent important examples of isotope usage within biosynthetic studies is presented, with

• ], but these aspects will not be discussed here. Instead, this review highlights recent biosynthetic studies using isotopes from major classes of natural products including polyketides, non-ribosomal peptides, hybrids thereof, isoprenoids and a few aromatic compounds that arise via the shikimate pathway

• careful evaluation of feeding experiments with labeled precursors. PKS/NRPS-Hybrids The formation of interesting structural motifs in natural products is an exciting aspect in the field of biosynthetic research and gives insights to the synthetic abilities of nature fusing structures, whose formation

Design and synthesis of propellane derivatives and oxa-bowls via ring-rearrangement metathesis as a key step

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1727–1731, doi:10.3762/bjoc.11.188

• propellane/oxa-bowl hybrids 7a,b in 71% and 97% yields, respectively. The new compounds 2c, 4b, 1c, 8a,b, 9, 6a,b and 7a,b have been fully characterized by using spectroscopic techniques (1H, 13C NMR and DEPT-135) and HRMS data. Conclusion We have successfully synthesized diverse heterocycles 1a–c in a

• simple manner starting from the known DA adducts 3a–c, including the propellane/oxa-bowl hybrids 7a,b and propellane derivative 5a. Interestingly, the structurally complex propellane/oxa-bowl hybrids 7a,b were obtained through a four step synthetic sequence starting from simple DA adducts 3b,c, which are

• -bowl 1a via RRM. Synthesis of RRM products 1b and 5a starting from DA adduct 3b. Synthesis of the hexacyclic compound 1c using RRM. Synthesis of the propellane/oxa-bowl hybrids 7a,b via RRM. Supporting Information Supporting Information File 292: Detailed experimental procedures, characterization data

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• polymerization of tubulin in vitro. The same methodology might be applied to direct a drug by conjugation to a molecule binding to a specific receptor on cancer cells. Moreover, by using dicarboxylated linkers with a disulfide bridge, it was possible to generate dynamic libraries of dimeric hybrids based on

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• of solid support such as polystyrene may lead to the disadvantage of operating in heterogeneous media. In contrast to the stepwise syntheses of dendrimers and dendron hybrids, the hyperbranched polymers can be easily obtained in kilogram scale through one-pot reactions [10], maintaining properties

• decorated dendron-hybrids [47], the presence of water was crucial for aldol and Baylis–Hillman reactions, as recently reported by Miller and Portnoy [48]. To the best of our knowledge, the immobilization of chiral organocatalysts on hyperbranched polymeric support has remained unexplored. Therefore, we

DNA display of glycoconjugates to emulate oligomeric interactions of glycans

• Alexandre Novoa and
• Nicolas Winssinger

Beilstein J. Org. Chem. 2015, 11, 707–719, doi:10.3762/bjoc.11.81

• glycosylated hybrids As an alternative to DNA, peptide nucleic acid (PNA) [34] has also been used to tag glycans and to program their assembly based on the rules of hybridization. From an assembly standpoint, stable PNA–DNA duplexes can be achieved with shorter sequences than the corresponding DNA homoduplex

Autonomous assembly of synthetic oligonucleotides built from an expanded DNA alphabet. Total synthesis of a gene encoding kanamycin resistance

• Kristen K. Merritt,
• Kevin M. Bradley,
• Daniel Hutter,
• Mariko F. Matsuura,
• Diane J. Rowold and
• Steven A. Benner

Beilstein J. Org. Chem. 2014, 10, 2348–2360, doi:10.3762/bjoc.10.245

• nucleotide overlap with melting temperatures predicted to lie in a narrow range (44–56 °C; calculated without magnesium). OligArch also designed the sequences to have no-off target hybrids having a melting temperature greater than 25 °C, a full 20 °C below that predicted for the desired annealing pairs. Two

De novo macrolide–glycolipid macrolactone hybrids: Synthesis, structure and antibiotic activity of carbohydrate-fused macrocycles

• Richard T. Desmond,
• Anniefer N. Magpusao,
• Chris Lorenc,
• Jeremy B. Alverson,
• Nigel Priestley and
• Mark W. Peczuh

Beilstein J. Org. Chem. 2014, 10, 2215–2221, doi:10.3762/bjoc.10.229

Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label

• Nattawut Yotapan,
• Chayan Charoenpakdee,
• Pawinee Wathanathavorn,
• Boonsong Ditmangklo,
• Hans-Achim Wagenknecht and
• Tirayut Vilaivan

Beilstein J. Org. Chem. 2014, 10, 2166–2174, doi:10.3762/bjoc.10.224

• insertion in close proximity to the Nile red label. The results indicate that the Nile red label is located in a more hydrophobic environment in acpcPNA–DNA duplexes than in the single-stranded acpcPNA. The different fluorescence properties of the acpcPNA hybrids of complementary DNA and DNA carrying a base

• . Melting temperature data and optical properties of the Nile red-labeled acpcPNAs and their hybrids with various DNA are summarized in Table 2. Thermal denaturation experiments suggest that the Nile red-labeled acpcPNA 10mer-Nr can form a stable hybrid with complementary DNA. In contrast to some other

• resulted in a decrease of the quantum yield of more than 70% (ΦF = 0.04). Upon hybridization with complementary DNA targets, the fluorescence quantum yields of all four hybrids were increased to a similar range (ΦF = 0.15–0.23). However, since the initial fluorescence of 11merGG-Nr was low, the

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• rather limited. Zhang et al. obtained a series of pyrimidine nucleoside-thazolidinone hybrids 15 from 5-formyl-3',5'-di-O-acetyl-2'-deoxyuridine (14), an arylamine and mercaptoacetic acid (Scheme 6) [65]. The reactions were performed in a ionic liquid ([bmim]PF6). Products 15 were obtained in good to

• ]BF4 revealed that this solvent, when used in the fifth reaction cycle, still produced the target product in a good yield [92]. Biological activities of hybrids 63, 64 and 65 were evaluated [91][92]. Among them, hybrid 63a exhibited anti-leishmanian activity (IC50 = 10.6 ± 1.3 µM) [92]. The SAR study

• yields of products 69b and 70b derived from 5-formyl-2'-deoxyuridine (27) were slightly higher than yields of derivatives 69a and 70a obtained from the O-acetylated nucleoside 14. The syntheses of hybrids 71 [95] and 72 [96] represent examples of the Knoevenagel-initiated domino reactions where the

Influence of perylenediimide–pyrene supramolecular interactions on the stability of DNA-based hybrids: Importance of electrostatic complementarity

• Christian B. Winiger,
• Simon M. Langenegger,
• Oleg Khorev and
• Robert Häner

Beilstein J. Org. Chem. 2014, 10, 1589–1595, doi:10.3762/bjoc.10.164

• sciences. They play a crucial role in the stacking of nucleobases, thus stabilising the DNA double helix. The following paper describes a series of chimeric DNA–polycyclic aromatic hydrocarbon (PAH) hybrids. The PAH building blocks are electron-rich pyrene and electron-poor perylenediimide (PDI), and were

• incorporated into complementary DNA strands. The hybrids contain different numbers of pyrene–PDI interactions that were found to directly influence duplex stability. As the pyrene–PDI ratio approaches 1:1, the stability of the duplexes increases with an average value of 7.5 °C per pyrene–PDI supramolecular

• engage in any sort of Watson–Crick related hydrogen bonding, the individual strands interact via an interstrand stacking motif [45][46][47][48]. Herein we describe a series of DNA-based hybrids (Figure 1 and Table 1) containing electron-rich 1,8-dialkynylpyrenes (Y) and electron-poor perylenediimides

Pyrene-modified PNAs: Stacking interactions and selective excimer emission in PNA₂DNA triplexes

• Alex Manicardi,
• Lucia Guidi,
• Alice Ghidini and
• Roberto Corradini

Beilstein J. Org. Chem. 2014, 10, 1495–1503, doi:10.3762/bjoc.10.154

• , 10 mM NaH2PO4·H2O, 0.1 mM EDTA, pH 7.0, 1.25% DMF). All the samples were first incubated at 90 °C for 5 min, then slowly cooled to room temperature. Thermal denaturation profiles (A260 versus T) of the hybrids were measured with a UV–vis Lambda Bio 20 spectrophotometer equipped with a Peltier

Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

• Carlos Vila,
• Jonathan Lau and
• Magnus Rueping

Beilstein J. Org. Chem. 2014, 10, 1233–1238, doi:10.3762/bjoc.10.122

• recently Zhao reported the same reaction using C60-Bodipy hybrids [30] and porous material immobilized iodo-Bodipy [31] as photocatalysts, obtaining in both cases good yields for different pyrrolo[2,1-a]isoquinolines. Finally, Lu presented in 2013 a dirhodium complex for the synthesis of these compounds

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• (Figure 1) are different tris(heteroarylmethyl)amine ligands such as tris(pyridylmethyl)amines, tris(benzothiazolylmethyl)amines and tris(2-benzimidazolylmethyl)amines as well as hybrids of the latter (Table 1) [80][81][82][83]. These ligands have the same structural motif of a central tertiary amine

Host–guest complexes of mixed glycol-bipyridine cryptands: prediction of ion selectivity by quantum chemical calculations, part V

• Svetlana Begel,
• Ralph Puchta and
• Rudi van Eldik

Beilstein J. Org. Chem. 2013, 9, 1252–1268, doi:10.3762/bjoc.9.142

• donor atoms ([phen.phen.phen] and [bpy.bpy.bpy]) as well as the hybrids between them and [2.2.2] have not yet been studied sufficiently [50][51][52][53][54][55][56][57][58]. While the main concern was their photophysical and photochemical properties [51][52][54][55][56][59][60], their ability for

Synthesis of meso-substituted dihydro-1,3-oxazinoporphyrins

• Satyasheel Sharma and
• Mahendra Nath

Beilstein J. Org. Chem. 2013, 9, 496–502, doi:10.3762/bjoc.9.53

• of a new series of dihydro-1,3-oxazinoporphyrins in moderate to good yields. These novel porphyrin-dihydro-1,3-oxazine hybrids may be considered as potential candidates not only for biological evaluations but also for the development of newer π-conjugated molecules for various material applications

Multivalent display of the antimicrobial peptides BP100 and BP143

• Imma Güell,
• Rafael Ferre,
• Kasper K. Sørensen,
• Esther Badosa,
• Iteng Ng-Choi,
• Emilio Montesinos,
• Eduard Bardají,
• Lidia Feliu,
• Knud J. Jensen and
• Marta Planas

Beilstein J. Org. Chem. 2012, 8, 2106–2117, doi:10.3762/bjoc.8.237

• -melittin antimicrobial undecapeptide hybrids on a carbohydrate template could provide carbopeptides with improved biological properties. In particular, KKLFKKILKYL-NH2 (BP100) and KKLfKKILKYL-NH2 (BP143) were selected based on their high antibacterial activity against the plant pathogenic bacteria Erwinia

Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

• Gareth L. Nealon,
• Romain Greget,
• Cristina Dominguez,
• Zsuzsanna T. Nagy,
• Daniel Guillon,
• Jean-Louis Gallani and
• Bertrand Donnio

Beilstein J. Org. Chem. 2012, 8, 349–370, doi:10.3762/bjoc.8.39

• addressable 2-D and 3-D arrangements exhibiting high processability and self-healing properties. Herein, we review the developments in the field of discrete thermotropic liquid-crystalline nanoparticle hybrids, with special emphasis on the relationship between the nanoparticle morphology and the nature of the

• tetragonal), and the so-called banana phases formed by bent-core mesogens [30][34][35]. This review will focus on publications that describe the preparation and characterisation of discrete thermotropic liquid-crystalline nanoparticle hybrids. Thus topics such as micellar [36] or lyotropic NPs [37][38

• -/needlelike and platelike shapes, different strategies may be possible for inducing mesophase behaviour in these hybrids. In the case of rod-/needlelike NPs with high aspect ratios, their inherent shape lends itself to the formation of LC phases such as nematics and smectics, subject to the reduction of

Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

• Kristina Butković,
• Željko Marinić,
• Krešimir Molčanov,
• Biserka Kojić-Prodić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2011, 7, 1663–1670, doi:10.3762/bjoc.7.196

• hybrids of a number of mesomeric ionic structures (Figure 1). One of the most characteristic reactions of sydnones is the intermolecular 1,3-dipolar cycloaddition. In the presence of acetylenic or ethylenic dipolarophiles, sydnones undergo cycloaddition reactions, which can be induced thermally [4][6][7