Antifreeze glycopeptide diastereomers

• Lilly Nagel,
• Carsten Budke,
• Axel Dreyer,
• Thomas Koop and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 1657–1667, doi:10.3762/bjoc.8.190

• ); MS (ESI) m/z: [M + Na]+ 749.3. General synthetic procedure for the tert-butyl deprotection step (GP3) Fmoc-L-allo-Thr(GalNAc)-Ot-Bu (3A) or Fmoc-L-allo-Thr(GalNAc)-Ot-Bu (3B) was dissolved in a mixture of TFA and water (95:5) and stirred for 90 min. The volatiles were evaporated and the remaining

Approaches to α-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

• Sosale Chandrasekhar and
• V. Mohana Rao

Beilstein J. Org. Chem. 2012, 8, 1393–1399, doi:10.3762/bjoc.8.161

• bubbled in over 0.5 h. The mixture was stirred at room temperature for 6 h and the volatiles removed in vacuo. The residue was treated with water and worked up with CH2Cl2, etc., the crude products being purified by neutral Al2O3 (grade 1) column chromatography. Hofmann rearrangement of 9 to final

• carbamates 10 [21][22][23]. A stirred solution of 9 (0.2 mmol) in MeOH (5.0 mL) at 5–10 °C was treated with PhI(OAc)2 (0.2 mmol, one batch). After 15 min, the mixture was warmed to room temperature, and stirred for 1 h. The volatiles were removed in vacuo and the residue was treated with water and worked up

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part II: Iridomyrmecins

• Robert Hilgraf,
• Nicole Zimmermann,
• Lutz Lehmann,
• Armin Tröger and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1256–1264, doi:10.3762/bjoc.8.141

• , all eight stereoisomers of trans-fused iridomyrmecins were synthesized starting from the enantiomers of limonene. Combined gas chromatography and mass spectrometry including enantioselective gas chromatography revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain

• endohyperparasitoid wasp, Alloxysta victrix, we identified several acyclic terpenoids and the trans-fused (4S,4aR,7R,7aS)-dihydronepetalactone (X) as volatile components of cephalic secretions released by this species (Figure 1) [1][2]. However, gas chromatograms showed the presence of two additional major volatiles

• mitsugashiwalactone (25) [42] and its “nor-iridomyrmecin-complement” boschnialactone (26), [43] which all are plant volatiles, the methyl group in the typical five-membered ring of iridoids keeps its (S)-configuration (see also Figure 8), which is just in contrast to X and Z [44]. However, recently, two stereoisomers

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part I: Dihydronepetalactones

• Nicole Zimmermann,
• Robert Hilgraf,
• Lutz Lehmann,
• Daniel Ibarra and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1246–1255, doi:10.3762/bjoc.8.140

• of the other chiral centers during the synthesis. Basically, this approach could also be used for the synthesis of enantiomerically pure trans-fused iridomyrmecins. Using synthetic reference samples, the combination of enantioselective gas chromatography and mass spectrometry revealed that volatiles

• signaling pathways between primary parasitoids and hyperparasitoids. In order to gain further information about the chemical structures and the biological significance of corresponding signals, we examined the volatile components of pentane extracts from dissected heads as well as headspace volatiles of

• . Grant et al., found the trans-fused (1R,4aS,7R,7aR)-1-methoxy-4,7-dimethyl-1,4a,5,6,7,7a)-hexahydrocyclopenta[c]pyran, called (1R)-1-methoxymyodesert-3-ene, among the volatiles of the Ellangowan poison bush, which they transformed to the corresponding lactone a' [24]. Apart from this compound and very

Algicidal lactones from the marine Roseobacter clade bacterium Ruegeria pomeroyi

• Ramona Riclea,
• Julia Gleitzmann,
• Hilke Bruns,
• Corina Junker,
• Barbara Schulz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2012, 8, 941–950, doi:10.3762/bjoc.8.106

• Braunschweig, Germany 10.3762/bjoc.8.106 Abstract Volatiles released by the marine Roseobacter clade bacterium Rugeria pomeroyi were collected by use of a closed-loop stripping headspace apparatus (CLSA) and analysed by GC–MS. Several lactones were found for which structural proposals were derived from their

• investigate their activity against several bacteria, fungi, and algae. A specific algicidal activity was observed that may be important in the interaction between the bacteria and their algal hosts in fading algal blooms. Keywords: bacteria-algae symbiosis; lactones; Roseobacter; synthesis; volatiles

• volatiles released by Ruegeria pomeroyi The volatiles emitted by agar plate cultures of Ruegeria pomeroyi DSS-3 grown on ½ YTSS medium were collected on charcoal by using a closed-loop stripping apparatus (CLSA) [24]. After a collection time of about one day the adsorbed compounds were eluted with

Volatile organic compounds produced by the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria 85-10

• Teresa Weise,
• Marco Kai,
• Anja Gummesson,
• Armin Troeger,
• Stephan von Reuß,
• Silvia Piepenborn,
• Francine Kosterka,
• Martin Sklorz,
• Ralf Zimmermann,
• Wittko Francke and
• Birgit Piechulla

Beilstein J. Org. Chem. 2012, 8, 579–596, doi:10.3762/bjoc.8.65

• Xanthomonas campestris is a phytopathogenic bacterium and causes many diseases of agricultural relevance. Volatiles were shown to be important in inter- and intraorganismic attraction and defense reactions. Recently it became apparent that also bacteria emit a plethora of volatiles, which influence other

• development in Candida albicans [13], and Hogan et al. [14] concluded that either the bacteria modulate the fungal behavior or that C. albicans (or related fungi) responded to the presence of antagonistic bacteria in such a way that it was advantageous for the bacteria. Volatiles were also shown to support

• and facilitate cross-kingdom interactions, such as plant–insect communications as bi- and tritrophic attractions and defenses [15]. For example, volatiles emitted by vegetative plant tissues suppress the growth of microorganisms, both in the case of bacteria and fungi [16][17][18][19]. Recently, a new

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

• Thorben Nawrath,
• Georgies F. Mgode,
• Bart Weetjens,
• Stefan H. E. Kaufmann and
• Stefan Schulz

Beilstein J. Org. Chem. 2012, 8, 290–299, doi:10.3762/bjoc.8.31

• , Germany Pest Management Centre, Sokoine University of Agriculture, PO Box 3110, Chuo Kikuu, Morogoro, Tanzania Anti-Persoonmijnen Ontmijnende Product Ontwikelling (APOPO vzw), Groenenborgerlaan 171, 2020 Antwerpen, Belgium 10.3762/bjoc.8.31 Abstract Volatiles released by pathogenic and nonpathogenic

• mycobacteria, as well as by mycobacteria-related Nocardia spp., were analyzed. Bacteria were cultivated on solid and in liquid media, and headspace samples were collected at various times during the bacterial lifecycle to elucidate the conditions giving optimal volatile emission. Emitted volatiles were

• fatty-acid derivatives were released by pathogenic/nonpathogenic mycobacteria, while the two Nocardia spp. (N. asteroides and N. africana) emitted the sesquiterpene aciphyllene. Pathogenic Mycobacterium tuberculosis strains grown on agar plates produced a distinct bouquet with different volatiles, while

Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca

• Jeroen S. Dickschat,
• Hilke Bruns and
• Ramona Riclea

Beilstein J. Org. Chem. 2011, 7, 1697–1712, doi:10.3762/bjoc.7.200

• Jeroen S. Dickschat Hilke Bruns Ramona Riclea Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.7.200 Abstract The volatiles released by Micromonospora aurantiaca were collected by means of a closed-loop stripping apparatus

• for internal methyl branches in various chain positions, while the methyl ester function is derived from S-adenosyl methionine (SAM). Keywords: actinomycetes; FAMEs; fatty acid biosynthesis; GC–MS; volatiles; Introduction Lipids in general, and particularly fatty acids (FAs), belong to the most

• methylmalonyl-CoA was determined by feeding experiments [14]. During our ongoing analysis of the volatiles released by different bacteria and fungi with high potential for secondary metabolism, the actinomycete Micromonospora aurantiaca ATCC 27029 came to our attention. This gram-positive, sporulating bacterial

Structural conditions required for the bridge lithiation and substitution of a basic calix[4]arene

• Conrad Fischer,
• Wilhelm Seichter and
• Edwin Weber

Beilstein J. Org. Chem. 2011, 7, 1602–1608, doi:10.3762/bjoc.7.188

• , immediately changing the colour of the solution to yellow. Removal of all volatiles resulted in a yellow residue, which was dissolved in a small amount of methanol. By addition of water, a white precipitate was formed giving 5 after recrystallization from methanol as a microcrystalline solid. Yield: 0.9 g (46

• reflux, 9 equiv of MeI were added by syringe and heating was continued for 3 h. All volatiles were removed and the crude product was treated carefully with water. The solid was separated and dissolved in 30 mL CHCl3. After addition of MeOH, a white precipitate formed, which was collected and

Nano copper oxide catalyzed synthesis of symmetrical diaryl sulfides under ligand free conditions

• K. Harsha Vardhan Reddy,
• V. Prakash Reddy,
• A. Ashwan Kumar,
• G. Kranthi and
• Y.V.D. Nageswar

Beilstein J. Org. Chem. 2011, 7, 886–891, doi:10.3762/bjoc.7.101

• . The organic layer was washed successively with brine and water, and dried with Na2SO4. The solvent and volatiles were completely removed under vacuum to give the crude product, which was purified by column chromatography on silica gel to yield the analytically pure product in up to 94% yield. The

Gold-catalyzed naphthalene functionalization

• Pedro J. Pérez,
• M. Mar Díaz-Requejo and
• Iván Rivilla

Beilstein J. Org. Chem. 2011, 7, 653–657, doi:10.3762/bjoc.7.77

• mixture stirred for 24 h. Removal of volatiles followed by silica gel column chromatography (1:1 Et2O:petroleum ether) gave a mixture of products. The products 2a, 3b and 3c were identified by comparison with literature data [17][18][19], and 2b and 2c were compared authentic samples obtained from

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• (II) and Au(I) complexes in other asymmetric catalytic reactions. Experimental Synthesis of NHC–Pd(II) complex 7 Compound 5a (105.8 mg, 0.2 mmol) and [PdCl(η3-allyl)]2 (109.1 mg, 0.3 mmol), t-BuOK (56 mg, 0.5 mmol) were heated under reflux in THF (10 mL) for 8 h. The volatiles were then removed under

• in THF (10 mL) for 8 h. The volatiles were then removed under reduced pressure and the residue purified by a silica gel flash column chromatography (eluent: petroleum ether/ethyl acetate, 2:1–0:1) to give 8 as a white solid (94 mg, 65%). A single crystal grown from racemic complex 6a in a saturated

Protonation and deprotonation induced organo/hydrogelation: Bile acid derived gelators containing a basic side chain

• Uday Maitra and
• Arkajyoti Chakrabarty

Beilstein J. Org. Chem. 2011, 7, 304–309, doi:10.3762/bjoc.7.40

• volatiles, the crude product was purified by column chromatography on silica gel (2.5 cm × 10.0 cm) with 5–10% EtOH/CHCl3 as eluent to yield 0.53 g (97%) of the salt. The product was re-precipitated with CHCl3/hexane (1:20) and separated by centrifugation. This process was repeated twice to obtain the pure

The catalytic performance of Ru–NHC alkylidene complexes: PCy₃ versus pyridine as the dissociating ligand

• Stefan Krehl,
• Diana Geißler,
• Sylvia Hauke,
• Oliver Kunz,
• Lucia Staude and
• Bernd Schmidt

Beilstein J. Org. Chem. 2010, 6, 1188–1198, doi:10.3762/bjoc.6.136

• volatiles were evaporated. The residue was purified by chromatography on silica (hexane/MTBE 2:1). Yield of 4a using catalyst D: 139 mg (0.80 mmol, 80%). Yield of 4a using catalyst E: 160 mg (0.92 mmol, 92%). Yield of 4a using catalyst H: 170 mg (0.41 mmol, 41%). The ratios of lactone 4a to acrylate 3a were

• in dry and degassed toluene (390 mL). After adding the catalyst (D: 66.1 mg B: 73.9 mg H: 58.3 mg, 0.078 mmol, 10 mol %), the solution was stirred for 3 h at 80 °C. The solution was cooled to ambient temperature and all volatiles were evaporated. The residue was purified by chromatography on silica

• warmed to approximately 45 °C. Then the catalyst (0.025 mmol, 5 mol %, D: 42.4 mg E: 47.4 mg H: 18.7 mg) was added to the solution and stirred for 90 min at 80 °C. After cooling to ambient temperature all volatiles were evaporated and the residue purified by chromatography on silica. The rates of

New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

• Etienne Borré,
• Frederic Caijo,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2010, 6, 1159–1166, doi:10.3762/bjoc.6.132

• 5 h. Volatiles were removed under reduced pressure, acetone was added to the residue, and the solution was filtered trough a pad of Celite. The filtrate was concentrated and purified by chromatography on silica gel (pentane/acetone, 75/25) to yield the expected complexes 4a–i. (1,3

Self-assembly and semiconductivity of an oligothiophene supergelator

• Pampa Pratihar,
• Suhrit Ghosh,
• Vladimir Stepanenko,
• Sameer Patwardhan,
• Ferdinand C. Grozema,
• Laurens D. A. Siebbeles and
• Frank Würthner

Beilstein J. Org. Chem. 2010, 6, 1070–1078, doi:10.3762/bjoc.6.122

• . The volatiles were then removed at reduced pressure to yield the crude 2 as a colourless oil (97%). 1H NMR (400 MHz, CDCl3, TMS, 300 K): δ (ppm) = 7.15 (d, 1H), 6.95–6.83 (m, 1H), 6.83 (m, 1H), 4.65 (broad peak, 1H), 3.38 (t, J = 6.24 Hz, 2H), 3.01(t, J = 6.68 Hz, 2H), 1.44 (s, 9H); UV-vis (CH2Cl2

• solution of tert-butyl 2-(5-bromothiophene-2-yl)ethylcarbamate (3) in 5 mL CH2Cl2, 5 mL TFA was added and the reaction mixture stirred at rt under an argon atmosphere for 2 h. The volatiles were then removed under reduced pressure to afford the crude product as a light brown oil (96%) which was used in the

• . To this cold solution, 400 μL Bu3SnCl was added which caused the precipitate to dissolve immediately. The reaction mixture was stirred at room for further 12 h under an argon atmosphere. The volatiles were removed under reduced pressure to give the crude product as a white pasty mass. The crude

Development of dynamic kinetic resolution on large scale for (±)-1-phenylethylamine

• Lisa K. Thalén and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2010, 6, 823–829, doi:10.3762/bjoc.6.97

• reaction mixture was then stirred at 100 °C. After a reaction time of 72 h, the reaction was cooled to rt and the solids were removed by filtration through a sintered glass funnel. The solvent and other volatiles were subsequently removed in vacuo. Crystallization from Et2O:pentane afforded (R)-2-methoxy-N

• removed by filtration through a sintered glass funnel. The solvent and other volatiles were subsequently removed in vacuo. The crude product was purified by column chromatography (DCM:MeOH:NH3, 98:2:0.1 to 90:10:0.1) to afford 1.73 g (90%) of (R)-2-methoxy-N-(1-phenylethyl)acetamide (3) in 97% ee. Acyl

Preparation and Diels–Alder/cross coupling reactions of a 2-diethanolaminoboron- substituted 1,3-diene

• Liqiong Wang,
• Cynthia S. Day,
• Marcus W. Wright and
• Mark E. Welker

Beilstein J. Org. Chem. 2009, 5, No. 45, doi:10.3762/bjoc.5.45

• , 0.5 M HCl solution (100 mL) was added. The reaction mixture was extracted with Et2O (2 × 75 mL). The combined colorless clear organic layers were dried over MgSO4, and the volatiles were removed by a rotary evaporator (30 °C, 20 Torr) to yield the dieneboronic acid. The boronic acid was added at once

• refluxed for 36 h and cooled to room temperature. The solution was filtered through silica gel to remove catalysts. The filtrate was quenched with water (50 mL) and extracted with Et2O (4 × 50 mL). The combined organic layers were dried over MgSO4 and volatiles were removed by rotary evaporation. The

A simple route for renewable nano- sized arjunolic and asiatic acids and self- assembly of arjuna- bromolactone

• Braja G. Bag,
• Partha P. Dey,
• Shaishab K. Dinda,
• William S. Sheldrick and
• Iris M. Oppel

Beilstein J. Org. Chem. 2008, 4, No. 24, doi:10.3762/bjoc.4.24

• treated with LiBr (1.92 g, 22.08 mmol) and heated at 145 °C for 30 h. The volatiles were removed under reduced pressure and the crude product was purified by column chromatography to yield asiatic acid as a white solid (0.97 g, 90%). HPLC (reverse phase) tR = 9.0 min (Figure 1c). mp = 240–242 °C. [α]D298