(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• followed by treatment with yellow mercury (II) oxide [68]. There are two general strategies to access pseudoamide-type oligosaccharide mimics: i) nucleophilic addition of sugar derivatives to carbohydrate isocyanates, isothiocyanates or isocyanides; and ii) conversion of sugar azides into glycosyl

Synthetic incorporation of Nile Blue into DNA using 2′-deoxyriboside substitutes: Representative comparison of (R)- and (S)-aminopropanediol as an acyclic linker

• Daniel Lachmann,
• Sina Berndl,
• Otto S. Wolfbeis and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2010, 6, No. 13, doi:10.3762/bjoc.6.13

• ” ligation strategy has become an important strategy for postsynthetic labeling of DNA [12][13]. Huisgen described first the [2+3]-cycloaddition between alkynes and azides yielding 1,2,3-triazoles [14]. The utility of this reaction as a bioligation method has grown incredibly after Meldal [15] and – almost

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• (Scheme 12) [49]. Recently, Cozzi et al. showed that FC benzylations can proceed even without adding a Lewis acid catalyst, just “on water” at 80 °C. However, this method is restricted to reactive heteroarenes such as indole (30), pyrrole and nucleophiles including azides or acetylacetonates. Moreover

Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidines

• Gundula F. Starkulla,
• Elisabeth Kapatsina,
• Angelika Baro,
• Frank Giesselmann,
• Stefan Tussetschläger,
• Martin Kaller and
• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 63, doi:10.3762/bjoc.5.63

• nucleophilic substitution. The mesomorphic behaviour of these compounds was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS and SAXS) and revealed smectic A mesophases for bromides, chlorides and azides 3, 4 and 6. For these compounds a

• treatment with 5-bromopentanol or 6-bromohexanol, the hydroxy compounds 5d and 5e were isolated in 76% and 80% yield, respectively. To obtain the azides 6, bromides 3a–e were treated with NaN3 in DMF at 100 °C for 24 h and the products 6a–e were isolated in 74% up to quantitative yield (Scheme 4). In a

• melting transitions at 76 °C and 75 °C for compounds 5a,b and at 77 °C, 86 °C, 67 °C and 68 °C for the azides 7b–e, respectively (upon heating or cooling) in the DSC curve. Presumably, the higher polarity of the terminal hydroxy group with respect to the azido group, together with hydrogen bonding

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• the planned construction of the aziridine by tandem SN2 displacement. Exploiting the facial selectivity of compound 38, the direct introduction of an aziridine equivalent was attempted by 1,3-dipolar cycloaddition of an alkyl azide. As Frank noted, cycloaddition of azides to 3H-pyrrolo [1,2-a]indoles

• eclipsed by the olefinic hydrogen (compound 55) to minimize 1,3-allylic strain (Scheme 15) [61]. Attempts to introduce the aziridine from the olefin 48 using halogeno-azides like BrN3 or IN3 and subsequent reduction failed because the compound oxidized rapidly to the indoloquinone 58 (Scheme 16). A longer

Controlling hazardous chemicals in microreactors: Synthesis with iodine azide

• Johan C. Brandt and
• Thomas Wirth

Beilstein J. Org. Chem. 2009, 5, No. 30, doi:10.3762/bjoc.5.30

• Johan C. Brandt Thomas Wirth Cardiff University, School of Chemistry, Park Place, Cardiff CF10 3AT, UK. 10.3762/bjoc.5.30 Abstract Aromatic aldehydes have been converted into the corresponding carbamoyl azides using iodine azide. These reactions have been performed safely under continuous flow

• potentially hazardous compounds is another advantage of microreactors as only very small amounts of compounds/reagents are handled. Large inventories of dangerous reagents and intermediates are not necessary. Azides are among the most versatile reagents in modern organic chemistry however they are not often

• used to their full potential due to safety concerns. Especially azides with low molecular weights are difficult to handle because of their high disposition to detonate [3][4][5]. However, azides are extremely useful moieties in organic synthesis as they can be transformed easily into a large variety of

Dimerization of propargyl and homopropargyl 6-azido- 6-deoxy- glycosides upon 1,3-dipolar cycloaddition

• Nikolas Pietrzik,
• Daniel Schmollinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2008, 4, No. 30, doi:10.3762/bjoc.4.30

• -tetra-O-acetyl-glycosyl azides and ethyl 2,3,4-tri-O-acetyl-6-azido-6-deoxy-1-thio-glycosides, respectively [12]. In order to increase the structural diversity of glycosyl amino acid building blocks containing 1,2,3-triazole spacers even more, we next looked at the possibility to use glycosides bearing

Synthesis of 2-substituted 9-oxa-guanines {5-aminooxazolo[5,4-d]pyrimidin- 7(6H)-ones} and 9-oxa-2-thio- xanthines {5-mercaptooxazolo[5,4-d]pyrimidin- 7(6H)-ones}

• Subrata Mandal,
• Wen Tai Li,
• Yan Bai,
• Jon D. Robertus and
• Sean M. Kerwin

Beilstein J. Org. Chem. 2008, 4, No. 26, doi:10.3762/bjoc.4.26

• with benzyl azide or 2-morpholinoethyl azide in the presence of catalytic CuSO4 and sodium ascorbate to afford the triazoles 9 and 10, respectively, in good yield (Figure 5). The copper-catalyzed Huisgen cycloaddition of terminal alkynes and alkyl azides favors formation of the 1,4-triazole

Synthesis of new triazole- based trifluoromethyl scaffolds

• Michela Martinelli,
• Thierry Milcent,
• Sandrine Ongeri and
• Benoit Crousse

Beilstein J. Org. Chem. 2008, 4, No. 19, doi:10.3762/bjoc.4.19

• ]. The copper(I)-catalyzed 1,3-dipolar cycloaddition [33][34][35][36][37][38] of organic azides and alkynes (also called “click chemistry”) resulting in the formation of 1,2,3-triazoles has become an increasingly attractive area [39]. According to the literature [33][34][35][36][37][38], the Cu(I

• the presence of CuI (10 mol%) and showed good reactivity with completion of the reaction within 24 h, whereas the use of CuSO4/Na ascorbate afforded the cycloadduct in low yield. The reaction was then carried out with different propargylamines (N-(p-methoxyphenyl) and N-benzyl) and various azides at

• scaffolds from readily accessible propargylamines and azides through a copper (I) catalyzed 1,3-dipolar cycloaddition. The triazole derivatives were obtained in good yields and will be useful intermediates for further synthesis of new fluorinated foldamers and their conformational feature studies

Synthesis of crispine A analogues via an intramolecular Schmidt reaction

• Ajoy Kapat,
• Ponminor Senthil Kumar and
• Sundarababu Baskaran

Beilstein J. Org. Chem. 2007, 3, No. 49, doi:10.1186/1860-5397-3-49

• intramolecular Schmidt reaction of azides with carbonyl compounds.[11][12] Pearson and Aube have exploited the synthetic potential of the intramolecular Schmidt reaction in the synthesis of several indolizidine alkaloids. [11][12][13][14][15] Recently, we reported a novel approach for the construction of the

Synthesis of coumarin or ferrocene labeled nucleosides via Staudinger ligation

• Ivana Kosiova,
• Andrea Janicova and
• Pavol Kois

Beilstein J. Org. Chem. 2006, 2, No. 23, doi:10.1186/1860-5397-2-23

• Ivana Kosiova Andrea Janicova Pavol Kois Comenius University, Faculty of Natural Sciences, Department of Organic Chemistry, Mlynska dolina, Pavilon CH2, SK-84215 Bratislava, Slovak Republic 10.1186/1860-5397-2-23 Abstract Background Reaction of azides with triaryl phosphines under mild conditions

• starting compounds for preparation of modified nucleosides are azidonucleosides. In general, organic azides are valuable, energy-rich and flexible intermediates, which can react very differently under various reaction conditions. [13] They can react at N1 with electrophiles (carbon electrophiles, protons

• , boranes) and at N3 with nucleophiles, very frequently with phosphorous nucleophiles. Reaction of azides with triaryl phosphines under mild conditions gives iminophosphoranes without formation of any byproducts. [14] The intermediate which is formed almost quantitatively can be rapidly hydrolysed to the