Brønsted acid-promoted azide–olefin [3 + 2] cycloadditions for the preparation of contiguous aminopolyols: The importance of disiloxane ring size to a diastereoselective, bidirectional approach to zwittermicin A

• Hubert Muchalski,
• Ki Bum Hong and
• Jeffrey N. Johnston

Beilstein J. Org. Chem. 2010, 6, 1206–1210, doi:10.3762/bjoc.6.138

• Hubert Muchalski Ki Bum Hong Jeffrey N. Johnston Vanderbilt University and Vanderbilt Institute of Chemical Biology, Nashville, TN 37235, United States 10.3762/bjoc.6.138 Abstract We report the first study of substrate-controlled diastereoselection in a double [3 + 2] dipolar cycloaddition of

Halide exchanged Hoveyda-type complexes in olefin metathesis

• Julia Wappel,
• César A. Urbina-Blanco,
• Mudassar Abbas,
• Jörg H. Albering,
• Robert Saf,
• Steven P. Nolan and
• Christian Slugovc

Beilstein J. Org. Chem. 2010, 6, 1091–1098, doi:10.3762/bjoc.6.125

• . Complexes 2 and 3 were prepared by addition of excess potassium bromide (KBr) or potassium iodide (KI) to a suspension of 1 in methanol, following the procedures for similar transformations of different dichloro carbene complexes to their diiodo analogues [26]. In these cases THF [15][26] or acetone [27

• halogen” compound bearing a chloride and a bromide or an iodide ligand, respectively (Figure 2). Upon removal of the inorganic salts and addition of a further portion of KBr or KI, the equilibrium can be directed towards the desired product. Typically, three successive additions of the potassium salt are

• ratio of initiation rate to propagation rate (ki/kp) of a given initiator and monomer combination [30]. Polymers made with M2 and M31 were used for further comparison. M2 (ki/kp ≈ 1–0.01) is a typical initiator, producing in most cases polymers with high Mn values and high polydispersity indices (PDI

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• , as they react only with aliphatic halides [89][90][91][92]. However, it is known [116][117], that Hg(SCF3)2 forms a complex with KI which decomposes with the formation of an unstable anion “−SCF3”. Based on this observation, Adams and Clark used a mixture of trifluoromethylthiosilver and KI (or Bu4NI

• ) as a source of trifluoromethylthiolate anion for nucleophilic introduction of the trifluoromethylsulfanyl moiety into aromatic molecules [118]. Of the metal halides investigated for this reaction, the best results were obtained with KI and Bu4NI, whilst NaI, NaBr, and KF were ineffective. Some of

• these reactions are illustrated in Scheme 34. This reagent can displace a range of activated halides, particularly bromides and iodides. For the reaction of 2,4-(NO2)2C6H3X with AgSCF3/KI, the reactivity of the halogens occurs in the reverse sequence: F (26%) < Cl (52%) < Br (85%) < I (97%) [118

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

• molybdenum catalysts [7][8][9]. Often, the polydispersity indices of the resulting polymers obtained with initiator G1 are large with values ranging between 1.3 and 1.5 arising from an unfavorable rate of initiation (ki) relative to propagation (kp) as well as considerable secondary metathesis (backbiting

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

• coffee bean α-galactosidase (Table 1). All new compounds inhibited the Agrobacterium sp. enzyme better than the parent iminosugar 4. The pyrenyl substituted compound 19 with an extended aromatic system turned out to be the most active inhibitor with a Ki value of 60 nM against Agrobacterium sp. β

• -glucosidase/galactosidase and 0.25 µM against E. coli β-galactosidase. However, the toxicity of this compound clearly requires further evaluation. In general, N-substitution does not dramatically affect the inhibitory properties of the derivatives against β-galactosidase from E. coli, with Ki values

• -galactosidase from green coffee beans. However, the Ki values are still in the low µM range and thus, suitable for use as chemical chaperones. Gratifyingly, compounds 20 and 22 exhibited IC50 values of 10.9 µM (Ki = 2.0 µM) and 3.26 µM (Ki = 0.72 µM), respectively, with human lysosomal β-galactosidase. In

Synthesis and enzymatic evaluation of 2- and 4-aminothiazole- based inhibitors of neuronal nitric oxide synthase

• Graham R. Lawton,
• Haitao Ji,
• Pavel Martásek,
• Linda J. Roman and
• Richard B. Silverman

Beilstein J. Org. Chem. 2009, 5, No. 28, doi:10.3762/bjoc.5.28

• ], and murine iNOS [23] using a hemoglobin capture assay [24], giving Ki values of 10 μM, 1 mM and 50 μM, respectively. This corresponds to a significant loss in potency toward nNOS relative to lead compound 2 [Ki(nNOS) = 0.085 μM, Ki(eNOS) = 85 μM, Ki(iNOS] = 9 μM), suggesting that the aminopyridine

Shape- persistent macrocycle with intraannular alkyl groups: some structural limits of discotic liquid crystals with an inverted structure

• Sigurd Höger,
• Jill Weber,
• Andreas Leppert and
• Volker Enkelmann

Beilstein J. Org. Chem. 2008, 4, No. 1, doi:10.1186/1860-5397-4-1

• of macrocycles with intraannular alkyl chains and extraannular PAH substituents. i) Pd(OAc)2, ligand, DBU, DMA (49%); BBr3, CH2Cl2 (99%); iii) I2/KI, ethylene diamine (quant.); iv) dimethyl sulfate, KOH, THF/water (50%); v) PdCl2(PPh3)2, CuI, piperidine/THF (71%); vi) Bu4NF, THF (97%); vii) CuCl

m-Iodosylbenzoic acid – a convenient recyclable reagent for highly efficient aromatic iodinations

• Andreas Kirschning,
• Mekhman S. Yusubov,
• Roza Y. Yusubova,
• Ki-Whan Chi and
• Joo Y. Park

Beilstein J. Org. Chem. 2007, 3, No. 19, doi:10.1186/1860-5397-3-19

• Andreas Kirschning Mekhman S. Yusubov Roza Y. Yusubova Ki-Whan Chi Joo Y. Park Institut für Organische Chemie and Zentrum für Biomolekulare Wirkstoffchemie (BMWZ), Leibniz Universität Hannover, Schneiderberg 1B, D-30167 Hannover, Germany The Siberian State Medical University, 2 Moskovsky trakt

• ). Additionally, the work was funded by the Fonds der Chemischen Industrie. Ki-Whan Chi thanks the University of Ulsan Research Fund 2006. We are grateful to Prof. Viktor Filimonov from Tomsk Polytechnic University for helpful discussions.

8-epi-Salvinorin B: crystal structure and affinity at the κ opioid receptor

• Thomas A. Munro,
• Katharine K. Duncan,
• Richard J. Staples,
• Wei Xu,
• Lee-Yuan Liu-Chen,
• Cécile Béguin,
• William A. Carlezon Jr. and
• Bruce M. Cohen

Beilstein J. Org. Chem. 2007, 3, No. 1, doi:10.1186/1860-5397-3-1

• ) itself, whose binding affinity (Ki = 43 nM) was reportedly greater than that of the natural epimer 2a (111 nM).[8] To explore this anomaly, we submitted a new sample of 2b for in vitro testing at the KOR. Binding affinity, potency and efficacy were determined as previously described (Table 1).[26] The

• binding affinity of 2b (Ki = 304 nM) was lower than those previously reported for salvinorin B (2a) under the same conditions (66, 111 or 155 nM).[7][8][27] An early report that 2a was inactive employed a different radiolabeled ligand, [3H]bremazocine.[28] Subsequent testing with [3H]diprenorphine by the

• same group gave concordant values for the relative affinity of 2a.[17] Thus, our data suggest that 2b in fact has a lower affinity than 2a, consistent with the general trend mentioned above. We also reexamined the epimeric acids 4.[16] In a previous report, 4a was found to be inactive (Ki > 1,000 nM

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• towards glycosidases, while the core structure and essential network of hydroxyl functionalities for enzyme recognition are retained. An important example is the 1-deoxynojirimycin (DNJ) family, for which DNJ itself is a competitive inhibitor of α-D-glucosidase (Ki = 8–25 μM),[10] while its derivatives