- IspC as target for antiinfective drug discovery: Synthesis, enantiomeric separation, and structural biology of fosmidomycin thia isosters
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The emergence and spread of multidrug-resistant pathogens are widely believed to endanger human health. New drug targets and lead compounds exempt from cross-resistance with existing drugs are urgently needed. We report on the synthesis and properties of
- Kunfermann, Andrea,Lienau, Claudia,Illarionov, Boris,Held, Jana,Gr?wert, Tobias,Behrendt, Christoph T.,Werner, Philipp,H?hn, Saskia,Eisenreich, Wolfgang,Riederer, Ulrich,Mordmüller, Benjamin,Bacher, Adelbert,Fischer, Markus,Groll, Michael,Kurz, Thomas
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- Novel reverse thia-analogs of fosmidomycin: Synthesis and antiplasmodial activity
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Thia analogs of fosmidomycin are potent inhibitors of the non-mevalonate isoprenoid biosynthesis enzyme 1-deoxy-D-xylulose 5-phosphate reductoisomerase (IspC, Dxr) of Plasmodium falciparum. Several new thioethers displayed antiplasmodial in vitro activity
- Lienau, Claudia,Gr?wert, Tobias,Alves Avelar, Leandro A.,Illarionov,Held, Jana,Knaab, Tanja C.,Lungerich,van Geelen,Meier, Dieter,Geissler, Stefanie,Cynis, Holger,Riederer, Ulrich,Buchholz,Kalscheuer, Rainer,Bacher, Adelbert,Mordmüller, Benjamin,Fischer, Markus,Kurz, Thomas
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- Carbocation-forming reactions in ionic liquids
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A number of trifluoroacetates, mesylates, and triflates have been studied in ionic liquids. Several lines of evidence indicate that all of these substrates react via ionization to give carbocationic intermediates. For example, cumyl trifluoroacetates give mainly the elimination products, but the Hammett ρ+ value of -3.74 is consistent with a carbocationic process. The analogous exo-2-phenyl-endo-3-deutero-endo-bicyclo-[2.2.1]hept-2-yl trifluoroacetate gives an elimination where loss of the exo-hydrogen occurs from a cationic intermediate. 1-Adamantyl mesylate and 2-adamantyl triflate react to give simple substitution products derived from capture of 1- and 2-adamantyl carbocations by the residual water in the ionic liquid. The triflate derivative of pivaloin, trans-2-phenylcyclopropylcarbinyl mesylate, 2,2-dimethoxycyclobutyl triflate, the mesylate derivative of diethyl (phenylhydroxymethyl)-thiophosphonate, and Z-1-phenyl-5-trimethylsilyl-3-penten- 1-yl trifluoroacetate all give products derived carbocation rearrangements (kΔ processes), anti-7-Norbornenyl mesylate gives products with complete retention of configuration, indicative of involvement of the delocalized 7-norbornenyl cation. 1,6-Methano[10]annulen-11-yl triflate reacts in [BMIM][NTf2] to give 1,6-methano[10]annulen-11-ol, along with naphthalene, an oxidized product derived from loss of trifluoromethanesulfinate ion. Analogous loss of CF3SO2- can be seen in reaction of PhCH(CF3)OTf. Ionic liquids are therefore viable solvents for formation of carbocationic intermediates via kc and k Δ processes.
- Creary, Xavier,Willis, Elizabeth D.,Gagnon, Madeleine
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p. 18114 - 18120
(2007/10/03)
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- Reaction of silyl thioketones with lithium diethylphosphite: First observation of Thia-Brook rearrangement
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Reaction of silyl thioketone 7 with lithium diethylphosphite at -98°C afforded a S-attack product 8 and formal C-attack products 10 and 11, which were formed by S-to-C migration of the phosphoryl group in the S-adduct followed by C-to-S migration of the silyl group (Thia-Brook rearrangement), in a ratio depending on the conditions. The relative facility of the Thia-Brook rearrangement was compared with that of the Brook rearrangement using the (t-butyldimethylsilyl)diphenylmethyl derivatives 22 and 23.
- Takeda, Kei,Sumi, Koichi,Hagisawa, Susumu
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p. 449 - 454
(2007/10/03)
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- The Nature of Cationic Intermediates Derived from α-Thiophosphoryl and α-Thiocarbonyl Mesylates. Neighboring Thiophosphoryl and Thiocarbonyl Participation
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A series of mesylate derivatives of α-hydroxy thiophosphonathes, RCH(OMs)PS(OEt)2 (8), have been prepared.These mesylates can react by kc processes under solvolytic conditions if cation stabilizing groups such as p-anisyl or p-thioanisyl groups are present.However, under conditions of appropriate electron demand, mesylates 8 can react by kΔ processes involving thiophosphoryl participation.The cyclic intermediate ions capture acetic acid at phosphorus and lead ultimately to α-thio acetate derivatives of phosphonates.This overall transformation converts the P=S function to the P=O group.Rates of acetolyses of 8 can exceed those of the O-phosphoryl analogues by large factors when kΔ processes are involved (as expected for anchimerically assisted processes).Mesylate derivatives of α-hydroxy thio esters, R2C(OMs)CSOCH3 (9), can also react by kΔ processes as shown by enhanced rates relative to simple ester analogues.The substrate (R)-(-)-PhCH(OMs)CSOCH3 (38) gives an acetolysis product that is largely retained, while 9 (R = Me) gave a large fraction of a rearranged product.These data all argue in favor of neighboring thiocarbonyl participation in 8, giving cyclized intermediate cations.The behavior of mesylates 8 and 9 can therefore be quite different from that of the corresponding O-phosphoryl and carbonyl analogues.Neighboring group participation in 8 and 9 accounts for the differences.The contrasting behavior of 8 and 9 also argues against neighboring phosphoryl or carbonyl participation in solvolyses of mesylate derivatives of α-hydroxy phosphonates or α-keto mesylates.
- Creary, Xavier,Mehrsheikh-Mohammadi, M. E.
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