Gold-catalyzed propargylic substitutions: Scope and synthetic developments

• Olivier Debleds,
• Eric Gayon,
• Emmanuel Vrancken and
• Jean-Marc Campagne

Beilstein J. Org. Chem. 2011, 7, 866–877, doi:10.3762/bjoc.7.99

• reactions of propargylic alcohol 1 with PhSO2NHOH in the presence of NaAuCl4 neither the propargylic substitution product 22 nor the expected isoxazoline 23 could be observed in the crude product. Instead a 1:1 mixture of unreacted alcohol 1 and compound 24 formally resulting from the addition of a second

• isoxazolines cannot be directly obtained from propargylic alcohols 1 in the presence of gold(III) catalysts. From these preliminary experiments, it appears that the addition of hydroxylamine to the isoxazoline double bond is much faster than propargylic substitution. Consequently, the only possibility to

•  15 proved to be efficient and compounds 23a–i were obtained in 38–86% yield (Scheme 15). Prompted by the apparently simplicity of the addition of hydroxylamine to the isoxazoline double bond (Scheme 12), we next tried to promote the gold-catalyzed addition of various nucleophiles. As illustrated in

Photocycloaddition of aromatic and aliphatic aldehydes to isoxazoles: Cycloaddition reactivity and stability studies

• Axel G. Griesbeck,
• Marco Franke,
• Jörg Neudörfl and
• Hidehiro Kotaka

Beilstein J. Org. Chem. 2011, 7, 127–134, doi:10.3762/bjoc.7.18

• evaporated. The crude product was obtained as a yellow oil and used immediately without further purification. 3-Methyl-5-trimethylsilyloxy-2-isoxazoline (2) [19]. A mixture of acrylonitrile (10.61 g, 0.2 mol, 13.2 mL), triethylamine (10.12 g, 0.1 mol, 13.9 mL) and 1 (28.73 g, 0.2 mol) in toluene (90 mL) was

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• ), 62.23 (C-3), 61.21 (C(CH3)3, 53.71 (C-1’’), 39.07 (C-4), 35.92 (C-2’), 25.91 (C-4’), 25.91 (C(CH3)3), 25.85 (C-3’), 14.45 (OCH2CH3); MS (ESI): m/z [M+Na]+ calculated for C21H36N2O8[Na]+ 467.2, found 467.2. N-(Hex-5’-ynoyl)neuraminic acid (3) Isoxazoline (2.50 g, 5.63 mmol) and NaOMe (0.74 mL of 5.4 M

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

• the “normal” 5-substituted isoxazoline is formed. Hence, the nitrodecene 123 gives rise to only the nine-membered carbocycle 125 upon reaction with phenyl isocyanate. The matching HOMO-LUMO interactions for such cycloadditions favour the formation of 126 but ring strain and transannular steric effects

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• abovementioned pathogens with respect to the first GM generation. Toxicity studies on mammalian (including human) cell lines revealed a lower in vitro toxicity than the clinically used compound, amphotericin B. Oxime 57, isoxazoline 58 and isoxazole 59 derivatives were prepared in the Bristol-Myers Squibb