Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

• Paul W. Davies,
• Nicolas Martin and
• Neil Spencer

Beilstein J. Org. Chem. 2011, 7, 839–846, doi:10.3762/bjoc.7.96

• -disubstituted products could be achieved in quantitative yields when the counter ion was the more basic tosylate [19]. Alternatively, the use of protic, ethereal or aromatic solvents favoured the formation of the 2,5-disubstituted products regardless of the counter ion. Similar solvent regimes were employed in

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, C_nH_n and closo-boranes [B_xH_x]²⁻

• Michael J. McGlinchey and
• Henning Hopf

Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30

• manipulation led to the iodo-tosylate 39 which, in the presence of base, generated the homohypostrophene, 40; [2 + 2] cycloaddition then furnished the homopentaprismanone 41. Introduction of a bridge head bromine (with the intent of carrying out a Favorskii ring contraction) proved to be impossible. Instead it

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• ][76] were prepared. One-pot EYCM followed by Brønsted acid catalyzed cyclization enabled the formation of monounsaturated cyclic amines [77]. The EYCM of homopropargylic tosylate with allylic alcohol derivatives has been used as a key step for the construction of the side chain of mycothiazole [78

Carbasugar analogues of galactofuranosides: α-O-linked derivatives

• Jens Frigell and
• Ian Cumpstey

Beilstein J. Org. Chem. 2010, 6, 1127–1131, doi:10.3762/bjoc.6.129

• were observed and were not isolated in a pure form. The free OH-2 could then be converted to its tosylate 7. Treatment of this diester 7 with sodium methoxide resulted in the direct formation of the required epoxide 4, presumably by cleavage of the C1 benzoate to the alcoholate (with retention of

• configuration) followed by intramolecular displacement of the C2 tosylate (with inversion of configuration). We synthesised the same epoxide 4 (78%) by treatment of isolated 3,5,6-tri-O-benzyl-2-O-(toluene-4-sulfonyl)-4a-carba-β-D-galactofuranose [9] with sodium hydride in DMF. We investigated ring-opening of

β-Hydroxy carbocation intermediates in solvolyses of di- and tetra-hydronaphthalene substrates

• Jaya S. Kudavalli and
• Rory A. More O'Ferrall

Beilstein J. Org. Chem. 2010, 6, 1035–1042, doi:10.3762/bjoc.6.118

• . Surprisingly, while the solvolysis of trans-2-methoxycyclohexyl tosylate has been well studied [17], there appear to have been no measurements reported for its cis isomer. We cannot compare these rate ratios directly with those for the solvolyses of cis- and trans-1-trichloroacetoxy-2

Synthesis and crystal structures of multifunctional tosylates as basis for star-shaped poly(2-ethyl-2-oxazoline)s

• Richard Hoogenboom,
• Martin W. M. Fijten,
• Guido Kickelbick and
• Ulrich S. Schubert

Beilstein J. Org. Chem. 2010, 6, 773–783, doi:10.3762/bjoc.6.96

• -oxazolines resulting in star-shaped polymers. The synthesis of the tosylates was performed by esterification of the corresponding alcohols with tosyl chloride. Recrystallization of these tosylate compounds afforded single crystals, and the X-ray crystal structures of di-, tetra- and hexa-tosylates are

• reported. The use of tetra- and hexa-tosylates, based on (di)pentaerythritol as initiators for the CROP of 2-ethyl-2-oxazoline, resulted in very slow initiation and ill-defined polymers, which is most likely caused by steric hindrance in these initiators. As a consequence, a porphyrin-cored tetra-tosylate

• initiator was prepared, which yielded a well-defined star-shaped poly(2-ethyl-2-oxazoline) by CROP as demonstrated by SEC with RI, UV and diode-array detectors, as well as by 1H NMR spectroscopy. Keywords: cationic polymerization; crystal structure; living polymerization; star-polymer; tosylate

Synthesis and crystallographic analysis of meso-2,3-difluoro-1,4-butanediol and meso-1,4-dibenzyloxy-2,3-difluorobutane

• Bruno Linclau,
• Leo Leung,
• Jean Nonnenmacher and
• Graham Tizzard

Beilstein J. Org. Chem. 2010, 6, No. 62, doi:10.3762/bjoc.6.62

• 3 as a building block, in particular for the construction of longer aliphatic chains of varying length, was investigated next. Thus (Scheme 2), the diol moiety in 3 was monoprotected as a silyl ether, and the remaining alcohol group was activated as the corresponding tosylate 9, triflate 10

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• were difficult to separate from the desired compounds. The addition of triethylene glycol derivatives was also attempted by coupling triethylene glycol, or an activated triethylene glycol derivative bearing a tosylate or a chlorine atom at the ω-position. This latter approach proved to be better. The

Synthesis of lipophilic 1-deoxygalactonojirimycin derivatives as D-galactosidase inhibitors

• Georg Schitter,
• Elisabeth Scheucher,
• Andreas J. Steiner,
• Arnold E. Stütz,
• Martin Thonhofer,
• Chris A. Tarling,
• Stephen G. Withers,
• Jacqueline Wicki,
• Katrin Fantur,
• Eduard Paschke,
• Don J. Mahuran,
• Brigitte A. Rigat,
• Michael Tropak and
• Tanja M. Wrodnigg

Beilstein J. Org. Chem. 2010, 6, No. 21, doi:10.3762/bjoc.6.21

• % yield by ring nitrogen alkylation with tosylate 21 (Scheme 5) [43]. Inhibition constants of the compounds synthesised are presented in Table 1. The 1-deoxygalactonojirimycin analogues were tested as inhibitors of Agrobacterium sp. β-glucosidase/galactosidase and E. coli β-galactosidase as well as green

Three step synthesis of single diastereoisomers of the vicinal trifluoro motif

• Vincent A. Brunet,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2009, 5, No. 61, doi:10.3762/bjoc.5.61

• the requisite α,β-epoxy alcohols 6b and 7b. Three step sequential fluorination from α,β-epoxy alcohols to eg. the vicinyltrifluoro tosylate 11. Unexpected cyclisation of 9b to furan 14 with HF·pyridine. An X-ray structure of 14 (CCDC 750309) reveals that the cyclisation proceeds with a retention of

• configuration. Epoxide ring opening of 9b with 3HF·Et3N required forcing conditions. The structure and stereochemistry 12b (CCDC 750308) and 16 (CCDC 750310) was established by X-ray analysis. Three step sequential fluorination from α,β-epoxy alcohol 7b to vicinal trifluoro tosylate 17b. Epoxide ring opening

• with 3HF∙Et3N and synthesis of the all-syn vicinal trifluoro tosylate 17a. Reaction of α,β-epoxy alcohol 7a and 7b under various fluorination conditions. Ratios determined by 19F NMR. Supporting Information Supporting Information File 80: Experimental methods and full characterisation and spectral

Synthesis of mesogenic phthalocyanine-C₆₀ donor–acceptor dyads designed for molecular heterojunction photovoltaic devices

• Yves Henri Geerts,
• Olivier Debever,
• Claire Amato and
• Sergey Sergeyev

Beilstein J. Org. Chem. 2009, 5, No. 49, doi:10.3762/bjoc.5.49

• modest yields of 10a–d actually correspond to those reported earlier for other A3B-type phthalocyanines: yields higher than 20% are rare in such reactions [45][49][50][51]. The MEM protective group in 10a–d was then quantitatively removed to give 4a–d upon treatment with pyridinium tosylate (PPTS) in t

(−)-Complanine, an inflammatory substance of marine fireworm: a synthetic study

• Kazuhiko Nakamura,
• Yu Tachikawa and
• Daisuke Uemura

Beilstein J. Org. Chem. 2009, 5, No. 12, doi:10.3762/bjoc.5.12

• Discussion Our synthesis started from the known compound 3 [5][6] that could be derived from (R)-malic acid, (R)-2, in three steps (1. BH3·SMe2; 2. cat. TsOH, Et2CO; 3. TsCl, pyridine) (Scheme 1). The resultant tosylate 3 was treated with lithium acetylide ethylenediamine complex to give the terminal

• Synthesis of alkyne 4: To a solution of tosylate (3, 3.00 g, 9.1 mmol) in DMSO (10 ml), a lithium acetylide ethylene diamine complex (1.00 g, 11.0 mmol) was added under nitrogen atmosphere. After stirring for 3 h, an extractive workup and column chromatography (SiO2, hexane/ethyl acetate 99 : 1) gave the

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• 199 to 200 in the presence of InCl3 afforded the bis-adduct, anti-diol 201. The derived tosylate 202 was converted to the bis-THF core unit 203 upon treatment with TBAF. Oxidation to aldehyde 204 followed by InCl3-promoted addition of the (S)-allylic stannane 205 gave the anti adduct 206. Removal of

• the OH group by reduction of the tosylate 207 with LiBEt3H yielded the SEM ether 208. Conversion to the vinyl iodide 209 followed by Pd0-catalyzed coupling with the (S)-alkynyl butenolide 210 gave the asiminocin precursor 211. Selective hydrogenation of the enyne moiety with diimide and cleavage of

Convenient method for preparing benzyl ethers and esters using 2-benzyloxypyridine

• Susana S. Lopez and
• Gregory B. Dudley

Beilstein J. Org. Chem. 2008, 4, No. 44, doi:10.3762/bjoc.4.44

• the synthesis of benzyl ethers are equally relevant for the synthesis of halobenzyl ethers (3a → 7, 98% yield). Finally, replacement of methyl triflate with less reactive methylating reagents, including dimethyl sulfate (Me2SO4), methyl tosylate (MeOTs), and methyl iodide (MeI), did not provide

• [33][34] (2-chloro-1-methylpyridinium iodide). If release of the reactive benzyl electrophile (which begins to occur upon warming) competes with N-methylation of pyridine, then side reactions and alternative pathways emerge. For example, Paquette and co-workers report that the use of methyl tosylate

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

• , the latter was stirred with NaN3 in DMF (48 h, 65 °C) to afford 4a in 44% yield. The preparation of compound 4a via the corresponding tosylate 3a was somewhat more convenient than the synthesis via the 6-bromo-6-deoxy counterpart 3a'' and resulted in a similar overall yield. Therefore, all other 6

A divergent asymmetric approach to aza-spiropyran derivative and (1S,8aR)-1-hydroxyindolizidine

• Jian-Feng Zheng,
• Wen Chen,
• Su-Yu Huang,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2007, 3, No. 41, doi:10.1186/1860-5397-3-41

• leading to the bicyclic indolizidine.[40] Second, we have also observed that the tosylate of 8 is too labile to be isolated, and mesylate 12 decomposed upon flash column chromatography on silica gel, which are due to the spontaneous formation of a polar quaternary ammonium salt. In addition, the presence

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• -game sequence. Interestingly, the N-Boc group appears in its s-trans form, with the carbonyl oxygen pointing away from C-4. Compound 16 was then converted in high yield to tosylate 17 for the final cyclization, hydrolysis and reduction sequence to target (Scheme 5). Exposure of 17 to TFA at 0°C

• followed by addition of Hünig's base resulted in cyclization to indolizidine 18, which was isolated chromatographically as a tosylate salt in 56% yield. Compound 18 was identified from its NMR data. In particular, C-3(H-3), C-5(H-5) and C-8a(H-8a) resonated ≈ 10 ppm (C) and 1 ppm (H) downfield respectively

Synthesis of phosphorothioates using thiophosphate salts

• Babak Kaboudin and
• Fatemeh Farjadian

Beilstein J. Org. Chem. 2006, 2, No. 4, doi:10.1186/1860-5397-2-4

• route to phosphorothioates via O,O'-dialkyl thiophosphate anion formation. Studies on the reaction of ambident nucleophile ammonium O,O'-diethyl thiophosphate with benzyl halides and tosylate in different solvents show that only S-alkylation is obtained. Reaction of this ambident nucleophile with

• this reagent with benzyl bromide, chloride and tosylate in different aporotic and protic solvents show that S-benzyl O,O'-diethyl phosphorothioate (S-alkylation) was formed as sole product (Scheme 4). We conclude here that changing of leaving group and use of different media gives no O-alkylation

• on the reaction of ambident nucleophile ammonium O,O'-diethyl thiophosphate with benzyl halides and tosylate in different solvents show that only S-alkylation will be obtained as sole product. Reaction of this ambident nucleophile with benzoyl chloride (hard electrophilic center), gave the O