Profluorescent substrates for the screening of olefin metathesis catalysts

• Raphael Reuter and
• Thomas R. Ward

Beilstein J. Org. Chem. 2015, 11, 1886–1892, doi:10.3762/bjoc.11.203

• -methylpentanone and γ-butyrolactone), the Grubbs 2nd generation catalyst 3 performs best. In all cases, the initial ring-closing metathesis rates are highest with precatalyst 2. The same experiments were conducted with the fluorophore–quencher substrate 5 (Figure 3). In this case, the concentration of the

• : acetic acid; b: 2-methylpentanone; c: toluene; d: o-xylene; e: γ-butyrolactone; f: anisole). Fluorescence evolution resulting from closing metathesis of fluorescence–quencher substrate 5 (λexcitation = 320 nm and λemission = 400 nm). Different catalysts 1–4 (1: blue; 2: red, 3: green, 4: purple) were

• screened in different solvents (a: acetic acid; b: 2-methylpentanone; c: toluene; d: o-xylene; e: γ-butyrolactone; f: anisole). Comparison of kinetics measured by HPLC a) and by a plate reader b) for the ring-closing metathesis of 8 in acetic acid. Two profluorescent substrates yielding fluorescent

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid

• Ida Nymann Petersen,
• Jesper Langgaard Kristensen,
• Christian Tortzen,
• Torben Breindahl and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 641–646, doi:10.3762/bjoc.9.72

• glucuronide 2 was found to be almost completely stable in both buffer systems over the entire temperature range. Only after heating at 90 °C in acidic buffer for 3 days could a small amount of γ-butyrolactone (GBL) be detected (Figure 3). Under forcing acidic conditions (autoclaving for 15 min with 4 M aq HCl

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

• weapons against competitive fungi. As a first approach in our investigations, we analysed the profiles of its volatiles. Only two volatile organic compounds released by X. campestris have so far been described: 11-methyldodec-2Z-enoic acid [13] and γ-butyrolactone [28]. To extend this preliminary

Gold(I)-catalyzed synthesis of γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with alcohols

• Michel Chiarucci,
• Mirko Locritani,
• Gianpiero Cera and
• Marco Bandini

Beilstein J. Org. Chem. 2011, 7, 1198–1204, doi:10.3762/bjoc.7.139

• tolerance make this catalytic process a promising route for the synthesis of architecturally complex polycyclic structures. Keywords: alcohol; butyrolactone; carbene; gold-catalysis; intramolecular oxaallylic alkylation; Introduction Allylic alcohols are highly desirable, readily available, cheap, and

• conditions (Table 1). Initial attempts to perform the lactonization reaction of 1a were carried out by means of a silver-free cationic complex [P(t-Bu)2o-biphenyl](AuCH3CN)SbF6 (5 mol %). The desired butyrolactone 2a was obtained selectively under reflux in DCE for 16 h (entry 1), although only in low yield

• alkylation, 1g) dppf-based species (catalytic system B) led to a complex mixture of crude reaction products (entry 7), while carbene–gold complex provided mainly the butyrolactone 2g. Moreover, the methodology proved to be tolerant toward several functional groups/atoms at the methylene carbon atom of the

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

• provided directly the desired styrene 103 in good overall yield. A possible explanation for this fragmentation is outlined in Scheme 30. The enolate of ketone 104 reacts with oxygen to form the peroxide anion 105, which cleaves to give the α-keto-γ−butyrolactone 106. Treatment of the latter with aqueous

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

Stereoselective α-fluoroamide and α-fluoro- γ-lactone synthesis by an asymmetric zwitterionic aza-Claisen rearrangement

• Kenny Tenza,
• Julian S. Northen,
• David O'Hagan and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2005, 1, No. 13, doi:10.1186/1860-5397-1-13

• fluorinated products 24 and 25 gave diastereoisomeric γ-butyrolactone products (3R, 5R)-12 and (3R, 5S)-13 and (3S, 5R)-29 and (3S, 5S)-30 respectively, each in a ratio of 10:1 as shown in Scheme 8. The 12/13 mixture had an optical rotation of ([α]D = +15°) indicating a similar absolute stereochemistry to