Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones

• István E. Markó and
• Florian T. Schevenels

Beilstein J. Org. Chem. 2013, 9, 1319–1325, doi:10.3762/bjoc.9.148

• 59, or it may undergo addition of a water molecule, affording the hemiketal 60. Addition of a proton to the vinyl ether function, followed by intramolecular capture by the hydroxy group, finally provides the unique bridged adduct 62. Conclusion In summary, a unique anionic cascade process, leading to

Diastereoselective synthesis of nitroso acetals from (S,E)-γ-aminated nitroalkenes via multicomponent [4 + 2]/[3 + 2] cycloadditions promoted by LiCl or LiClO₄

• Leandro Lara de Carvalho,
• Robert Alan Burrow and
• Vera Lúcia Patrocinio Pereira

Beilstein J. Org. Chem. 2013, 9, 838–845, doi:10.3762/bjoc.9.96

• nitroalkenes 5a–c as heterodienes, ethyl vinyl ether (EVE) as a dienophile, and selected electron-deficient alkenes as 1,3-dipolarophiles. The employment of different organic solutions of LiClO4 or LiCl as promoter systems provided the respective nitroso acetals with yields from 34–72% and good levels of

• -diamines [19]. Herein, we report the reactivity and diastereoselectivity of 5a–c as heterodienes in a multicomponent [4 + 2]/[3 + 2] cycloaddition with ethyl vinyl ether (EVE) and selected electron-deficient alkenes in the presence of LiCl or LiClO4 as promoters. A study on the solvent effect was also

• besides conjugate addition [19] make them useful chiral building blocks for diastereoselective synthesis. Experimental General EtOH, MeOH, 2-propanol, toluene, LiClO4, LiCl, methyl vinyl ketone, ethyl vinyl ether, methyl acrylate and acrylonitrile were purchased from Aldrich, Acros or Merck and were used

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• [11]. Chain termination is commonly carried out by using ethyl vinyl ether or cis-butene derivatives, although incomplete end-capping has been reported as a limitation with the former [12]. Notable examples include an enol ether derivative that introduces a β-trimethylsilylethoxy protected carboxylic

• ethyl vinyl ether to render the catalyst inactive. The success of the capping reaction was assessed by 1H NMR. Complete capping was achieved in 20 minutes, as indicated by a 5:9 integration ratio for the phenyl and trimethylsilyl protons (see Supporting Information File 1). Longer reaction times did not

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

• Maddi Sridhar Reddy,
• Nuligonda Thirupathi and
• Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

• , pyrrolidine and salicylaldehydes led to a concomitant cycloisomerization followed by hydrolysis of the resultant vinyl ether to afford coumarins in a cascade process. The reaction proceeded through exclusive 6-endo-dig cyclization and is compatible with halo and keto groups giving coumarins in good to

• catalyst. That, after consecutive A3 coupling, cycloisomerization and hydrolysis of the resultant vinyl ether intermediate, should produce coumarins (Scheme 1, (d)). The reason for the selective 6-endo-dig cyclization of such a cooperative-catalysis reaction has been well documented through DFT

• intermediate B. Copper being coordinated with the amine group immediately activated the alkyne group to facilitate cycloisomerization with the phenoxy group, to produce vinyl ether C, which, being susceptible to hydrolysis, underwent water addition followed by an extrusion of the pyrrolidine molecule for

A Wittig-olefination–Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis

• Mukund G. Kulkarni,
• Mayur P. Desai,
• Deekshaputra R. Birhade,
• Yunus B. Shaikh,
• Ajit N. Dhatrak and
• Ramesh Gannimani

Beilstein J. Org. Chem. 2012, 8, 1725–1729, doi:10.3762/bjoc.8.197

• combined organic layer was dried over sodium sulfate, and ethyl acetate was evaporated under vacuum. The crude product, i.e., crotyl vinyl ether, was purified by using silica-gel column chromatography (mobile phase 1–3% ethyl acetate in petroleum ether). Crotyl vinyl ethers (a–h were obtained in 84–89

Combined bead polymerization and Cinchona organocatalyst immobilization by thiol–ene addition

• Kim A. Fredriksen,
• Tor E. Kristensen and
• Tore Hansen

Beilstein J. Org. Chem. 2012, 8, 1126–1133, doi:10.3762/bjoc.8.125

• reactivity of unsaturated compounds 6–9 towards the thiols is generally so: vinyl ether 6 > allyl ether 9 > acrylate 8 > methacrylate 7 [11]. Thiol–ene additions according to the anionic (Michael-type) mechanism have not been investigated in this work. As a minimum for obtaining cross-linked polymeric

• has an unusually high degree of cross-linking [16]. Unlike vinyl ether 6 and allyl ether 9, acrylic building blocks such as 7 and 8 may undergo some degree of acrylic homopolymerization during network formation, although the thiol–ene addition is usually more rapid than the polymerization. The ratio

Asymmetric total synthesis of smyrindiol employing an organocatalytic aldol key step

• Dieter Enders,
• Jeanne Fronert,
• Tom Bisschops and
• Florian Boeck

Beilstein J. Org. Chem. 2012, 8, 1112–1117, doi:10.3762/bjoc.8.123

• methyl vinyl ether with dilute acid liberated the ketone derivative 13. The synthesis of this starting material for the envisaged intramolecular aldol reaction could be conducted on a multigram scale without the need for column chromatography. Similar to the previously reported aldol reaction (Scheme 3

Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

• Supriya Dey and
• Narayanaswamy Jayaraman

Beilstein J. Org. Chem. 2012, 8, 522–527, doi:10.3762/bjoc.8.59

• methodology include the formation of vinyl halide, vinyl ether, diketone and diol intermediates, which are potential sites for varied types of functionalizations. While exploring such features, we undertook the preparation of septanoside derivatives that are branched out at C-2, so as to afford 2-deoxy-2-C

Binding of group 15 and group 16 oxides by a concave host containing an isophthalamide unit

• Jens Eckelmann,
• Vittorio Saggiomo,
• Svenja Fischmann and
• Ulrich Lüning

Beilstein J. Org. Chem. 2012, 8, 11–17, doi:10.3762/bjoc.8.2

• h at room temperature. The reaction was quenched with ethyl vinyl ether (2 mL) and the mixture was stirred for 1 h. The solvent was removed under reduced pressure and the crude product was filtered over silica gel (1 cm, dichloromethane/methanol, 40:1). The solvent was removed and cyclohexane/ethyl

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• conditions, one diastereomer was cleanly and completely transformed into the other one (Scheme 11) [10]. Hallberg and coworkers developed a one-pot strategy towards the synthesis of masked 3-aminoindan-1-ones 23. This process was initiated by Heck addition of an aryl triflate to a vinyl ether, leading to an

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• external vinyl ether 4, leading to interesting 9-oxabicyclo[3.3.1]nona-4,7-dienes 5 in good yields (Scheme 2). In view of the highly stereoselective outcome of these reactions and the requirement of an alkoxy or acyloxy group at the propargylic position of 3, the authors proposed a reaction pathway based

• highly stereoselective (4 + 2) cycloaddition with the vinyl ether to yield, after the elimination of the gold catalyst, highly substituted oxacyclic systems 7 in good yields and with notable diastereoselectivities. Importantly, this reaction tolerates a wide range of vinyl ethers, and different

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• phenylacetylene the ratio of vinyl ether 47 to ketal 48 can be controlled by the choice of catalyst (Scheme 8). The gold-catalyzed intramolecular 6-endo-dig cyclization of β-hydroxy-α,α-difluoroynones 50 under mild conditions has been developed (Scheme 9) [34]. The result indicated that gold catalysis is

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• formation of the 1,4-furan dipole (Scheme 21). In fact, a resonance structure of 60 can be envisaged entailing a gold–carbene and a carbonyl ylide 63. Upon 1,3-dipolar cycloaddition with the alkoxy vinyl ether, bridged bicycle 64 is formed. 1,2-Alkyl migration and bridge opening produces a spiro cation 66

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• that reaction is initiated on the vinyl ether (vinylamine) group of 74a/b to give 5-aminopyrazole-4-carbonitrile 76 through the intermediacy of 75 [59]. However, Elnagdi et al. [60] have reported that when ethyl hydrazinoacetate condenses with 74a or b, a change in regiochemistry occurs to yield 3

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

• (Scheme 13) [68]. This is surprising as enol ethers are known to be moderately reactive in olefin metathesis [69] and ethyl vinyl ether is often used to stop ring opening metathesis polymerizations. Vinyl acetate is also a good partner for EYCM under similar conditions. In the presence of 10 mol % of

• Grubbs II catalyst and 2 equiv of CuSO4, the cross-metathesis of terminal alkynes with ethyl vinyl ether led to the expected dienyl ether at 80 °C under microwave heating in toluene, whereas in H2O/t-BuOH conjugated enals were formed [70]. As already mentioned with dienes resulting from EYCM with

• decomposition and maintain catalytic activity. It has also been shown that the presence of ethylene had a beneficial effect either on reactivity or on stereoselectivity in EYCM. The EYCM of vinyl ether, which was successful with some selected alkynes [68], failed when propargylic thiobenzoates were used as

Hoveyda–Grubbs type metathesis catalyst immobilized on mesoporous molecular sieves MCM-41 and SBA-15

• Hynek Balcar,
• Tushar Shinde,
• Naděžda Žilková and
• Zdeněk Bastl

Beilstein J. Org. Chem. 2011, 7, 22–28, doi:10.3762/bjoc.7.4

• ) were taken at given intervals, quenched with ethyl vinyl ether and analyzed by GC. In the ROMP experiments, the reaction conditions were similar to those for the RCM of 1,7-octadiene, with an initial concentration of cyclooctene of 0.6 mol/L. After 3 h, the reaction mixture was terminated with ethyl

• vinyl ether, the solid catalyst was separated by centrifugation and the polymer isolated by precipitation in methanol (containing 2,6-di-tert-butyl-p-cresol as an antioxidant). The polymer yield was determined gravimetrically. The molecular weight was determined by SEC and the values related to the

ROMP-Derived cyclooctene-based monolithic polymeric materials reinforced with inorganic nanoparticles for applications in tissue engineering

• Franziska Weichelt,
• Solvig Lenz,
• Stefanie Tiede,
• Ingrid Reinhardt,
• Bernhard Frerich and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, 1199–1205, doi:10.3762/bjoc.6.137

• compressive force-compression ratio (CF-C ratio) applied to the cross-sectional area. CaCl2·2H2O (99%) and NH4OH (aqueous 26 wt % solution) were obtained from Riedel-de Haën. Anhydrous Na2CO3 (99%), anhydrous Na2SO4 (99%), NaHCO3 (99+%), ethyl vinyl ether (99%, stabilized), 1,1,1-tris(hydroxymethyl)ethane (97

• (toluene, 9 wt %). Solutions A and B were mixed and stirred for a few seconds. The polymerization mixture was poured into 1 × 5 cm plastic devices. Polymer formation occurred within 12 hours in air. The monoliths were extensively washed with a mixture of CHCl3, DMSO and ethyl vinyl ether (2:40:28 wt

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• expected in the future. Experimental Materials 10-undecenoic acid (Sigma–Aldrich, 98%), 1,3-propanediol (Sigma–Aldrich, 99.6%), p-toluenesulfonic acid monohydrate (Sigma–Aldrich, 98.5%), ethyl vinyl ether (Sigma–Aldrich, 99%), sulfuric acid (Fluka, 95–97%), p-benzoquinone (Fluka, 98%), (1,3-bis(2,4,6

• from Radleys. Stirring was continued at the selected temperature under a continuous flow of nitrogen for 5 h. After 5 h reaction time, the reaction mixture was dissolved in 1 mL of THF and polymerization halted by the addition of 1 mL of ethyl vinyl ether. The mixture was then stirred for 30 min at

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• [28]. Thus water-soluble poly(hydroxy vinyl ether)s were copolymerized with oil-soluble maleate esters to yield polymer particles with capsular morphology as shown in Figure 2. While the formation of (hydrophilic) functionalized particles is straightforward in inverse miniemulsions, it most often

Total synthesis of (±)-coerulescine and (±)-horsfiline

• Mukund G. Kulkarni,
• Attrimuni P. Dhondge,
• Sanjay W. Chavhan,
• Ajit S. Borhade,
• Yunnus B. Shaikh,
• Deekshaputra R. Birhade,
• Mayur P. Desai and
• Nagorao R. Dhatrak

Beilstein J. Org. Chem. 2010, 6, 876–879, doi:10.3762/bjoc.6.103

• allyloxymethylenetriphenylphosphorane under standard conditions [35] furnished the corresponding allyl vinyl ether 5 as an inseparable mixture of E and Z isomers. However, the NMR signals of the E and Z isomers in the olefinic region were well separated, which allowed us to estimate the ratio of these isomers as 1:2. The mixture of

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• -position). While the optical properties were quite similar, the EL properties were inferior. This was ascribed to a reduced conjugation length in these polymers. Novel vinyl ether-functionalized polyfluorenes for active incorporation in common photoresist materials were described by Kühne et al. [35] Among

• the polymers investigated was a diphenylDPP-fluorene copolymer, the fluorene units carrying ethyl vinylether groups in the 9,9´-position. The vinyl ether functionality allowed for active incorporation of the light emitting polymers into standard vinyl ether or glycidyl ether photoresist materials, the

Novel tetracyclic structures from the synthesis of thiolactone-isatin hybrids

• Renate Hazel Hans,
• Hong Su and
• Kelly Chibale

Beilstein J. Org. Chem. 2010, 6, No. 78, doi:10.3762/bjoc.6.78

• indicated by X-ray crystallographic data. The absence of the other diastereomer may be due to destabilizing steric interactions with the carbonyl group of the amide and the oxygen of the vinyl ether. Similar cyclizations leading to bridged lactams have been reported [43][44]. Synthesis of tetracycles 4 was

Addition of lithiated enol ethers to nitrones and subsequent Lewis acid induced cyclizations to enantiopure 3,6-dihydro-2H-pyrans – an approach to carbohydrate mimetics

• Fabian Pfrengle and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 75, doi:10.3762/bjoc.6.75

• good yields and stereoselectivities, 5 equivalents of the nucleophile were necessary to achieve reasonable yields in the addition to the nitrone/chlorodiethylaluminium complexes. Despite this, diastereomeric ratios in favour of the anti-products were generally excellent. Lithiated ethyl vinyl ether was

• is in line with the addition of other nucleophiles to nitrone 2a [9][10][11]. The configurations of compounds 4 could be unambiguously assigned by X-ray crystallographic analysis of an aminopyran derivative derived from anti-4b (compound 29, Scheme 12) [8]. The enol ethers used, i.e., ethyl vinyl

• ether, dihydropyran, and dihydrofuran, all added smoothly to glyceraldehyde-derived nitrones 2a or 2b after lithiation with tert-butyllithium. Whereas in the reaction with uncomplexed nitrones, 1.5 equivalents of the respective lithiated enol ether were sufficient to obtain the desired syn-products with

Synthesis and crossover reaction of TEMPO containing block copolymer via ROMP

• Olubummo Adekunle,
• Susanne Tanner and
• Wolfgang H. Binder

Beilstein J. Org. Chem. 2010, 6, No. 59, doi:10.3762/bjoc.6.59

• polymer synthesis. Alternatively, Grubbs’ third generation catalyst G3 introduced by Grubbs et al. [10] has an ultrafast initiating ruthenium benzylidene. The rate of reaction of G3 with ethyl vinyl ether thus is six orders of magnitude higher than for G2 [10], leading to a faster initiation and often

• in 1 ml of CH2Cl2 was then added. After 5 min of stirring at room temperature, the total consumption of monomer A 7 was confirmed by thin layer chromatography (TLC). The reaction was then quenched with 5 drops of cold ethyl vinyl ether, and the resulting polymer purified by column chromatography

• addition of cold ethyl vinyl ether. The polymer was isolated by column chromatography (SiO2) (eluent: DCM). Kinetic experiments A pyrene stock solution was prepared from 70 mg of pyrene dissolved in 2 ml of CDCl3. Monomer A 7 (20.83 mg, 0.099 mmol) dissolved in CDCl3 (0.2 ml) was first introduced into the

Acid catalyzed cyclodimerization of 2,2-bis(trifluoromethyl)-4-alkoxy-oxetanes and -thietanes. Synthesis of 2,2,6,6-tetrakis(trifluoromethyl)-4,8-dialkoxy-1,5-dioxocanes and 3,3,7,7-tetrakis(trifluoromethyl)-9-oxa-2,6-dithia-bicyclo[3.3.1]nonane

• Viacheslav A. Petrov and
• Will Marshall

Beilstein J. Org. Chem. 2010, 6, No. 46, doi:10.3762/bjoc.6.46

• bis(trifluoromethyl)ketene and ethyl vinyl ether [9][10]. In the case of oxetane 1d, the main channel of the reaction involves stabilization of intermediates A and B by H+ elimination, leading to the formation of olefins 2d and 2e, respectively. Such a distinct difference in the reactivity of 1d may