67755-97-9Relevant articles and documents
Influence of α-methyl substitution of proline-based organocatalysts on the asymmetric α-oxidation of aldehydes
Tong, Sok-Teng (Amy),Brimble, Margaret A.,Barker, David
experimental part, p. 4801 - 4807 (2009/10/09)
The direct asymmetric organocatalytic α-oxidation of aldehydes using trans-2-(p-methylphenylsulfonyl)-3-phenyloxaziridine is reported. This method affords the S isomer of α-hydroxy aldehydes, thereby complementing the selectivity for the R isomer observed using the two-step nitrosobenzene method. Use of α-methylproline and α-methylproline tetrazole significantly increases the enantioselectivity observed for the α-oxidation of aldehydes compared to analogous unsubstituted organocatalysts.
A novel approach to γ-hydroxy-α,β-unsaturated compounds
Krawczyk, Henryk,Wasek, Katarzyna,Kedzia, Jacek
experimental part, p. 3299 - 3306 (2009/05/11)
A simple synthesis of (E)-alk-1-enyl mesylates from (E)-alk-1- enylphosphonates is reported. Construction of γ-hydroxy-α,β- unsaturated compounds was achieved by a two-step process involving dihydroxylation of the enol mesylates followed by HWE reaction of the resulting α-hydroxy aldehydes with activated methylphosphonates. Enantioselective synthesis of the title compounds is also reported.
Kinetics of oxidation of pantothenic acid by chloramine-T in perchloric acid and in alkaline medium catalyzed by OsO4: A mechanistic approach
Puttaswamy,Jagadeesh
, p. 201 - 210 (2007/10/03)
Kinetics of oxidation of pantothenic acid (PA) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in the presence of HClO 4 and NaOH (catalyzed by OsO4) has been investigated at 313 K. The stoichiometry and oxidation products are same in both media; however, their kinetic patterns were found to be different. In acid medium, the rate shows first-order dependence on |CAT|o, fractional-order dependence on |PA|o, and inverse fractional-order on |H+|. In alkaline medium, the rate shows first-order dependence each on |CAT| o and |PA|o and fractional-order dependence on each of |OH-| and |OsO4|. Effects of added p-toluenesulfonamide and halide ions, varying ionic strength, and dielectric constant of medium as well as solvent isotope on the rate of reaction have been investigated. Activation parameters were evaluated, and the reaction constants involved in the mechanisms have been computed. The proposed mechanisms and the derived rate laws are consistent with the observed kinetics.
Product distributions from the OH radical-induced oxidation of but-1-ene, methyl-substituted but-1-enes and isoprene in NO(x)-free air
Benkelberg,Boge,Seuwen,Warneck
, p. 4029 - 4039 (2007/10/03)
Product distributions resulting from the OH-induced oxidation of but-1-ene, 2-methylbut-1-ene, 3-methylbut-1-ene and isoprene in air were measured in the absence of nitrogen oxides and compared with predictions based on currently accepted oxidation mechanisms. In the case of butenes, the observed distributions of carbonyl compounds, hydroxyketones, hydroxyalkanals and diols were evaluated to obtain probabilities for the initial attack of OH radical on the outer position of the double bond (y = 0.90 ± 0.03 for 2-Me-but-1-ene and y = 0.76 ± 0.05 for both but-1-ene and 3-Me-but-1-ene), for the probability of formation of stable products in the self-reaction of secondary β-hydroxyperoxyl radicals (k(ssb)/k(ss) = 0.29 ± 0.07 for but-1-ene and k(ssb)/k(ss) = 0.19 ± 0.06 for 3-Me-but-1-ene), and for the ratio of the reaction with oxygen vs. decomposition of β-hydroxyalkoxyl radicals, k3[O2]/(k4 + k3[O2]) = 0.25 ± 0.04 for but-1-ene and = 0.38 ± 0.04 for 3-Me-but-1-ene. The last two values disagree with other published data, which suggest a smaller effect of oxygen. The oxidation of isoprene produced methacrolein and methyl vinyl ketone with a ratio 0.93 ± 0.10, the ratio of methyl vinyl ketone and 3-methylfuran was 7.3 ± 1.0. Other products were 1-hydroxy-3-methylbut-3-en-2-one (identified by mass spectrometry) and 3-methyl-3-oxo-butane (tentatively identified). The overall product distribution was complex and could not be fully elucidated. Computer simulations based on several mechanisms applied the relative probabilities for OH addition found for the but-1-enes. Comparison with the experimental data suggests probabilities for OH addition to the methylated double bond of 0.504 ± 0.027 (outer position) and 0.056 ± 0.003 (inner position), and to the non-methylated double bond of 0.335 ± 0.023 (outer position) and 0.105 ± 0.008 (inner position).
Synthesis of Enantiomerically Pure α-Hydroxyaldehydes from the Corresponding α-Hydroxycarboxylic acids: Novel Substrates for Escherichia coli Transketolase
Humphrey, Andrew J.,Turner, Nicholas J.,McCague, Raymond,Taylor, Stephen J. C.
, p. 2475 - 2476 (2007/10/03)
Enantiomerically pure (R)-α-hydroxyaldehydes (>95percent ee) are prepared from the corresponding α-hydroxyesters by silyl protection, reduction with diisobutylaluminium hydride, and finally deprotection under acidic conditions; subsequent coupling of these aldehydes with lithium hydroxypyruvate, catalysed by Escherichia coli transketolase, leads to novel optically pure triols.
Additive Pummerer reactions of vinylic sulfoxides. Synthesis of γ-hydroxy-α,β-unsaturated esters, α-hydroxyketones, and 2-phenylsulfenyl aldehydes and primary alcohols
Craig, Donald,Daniels, Kevin,MacKenzie, A. Roderick
, p. 11263 - 11304 (2007/10/02)
Treatment of β-monosubstituted vinylic sulfoxides 1 with trifluoroacetic anhydride in dichloromethane gave excellent yields of 1,2-bis(trifluoroacetoxy)thioethers 6. Mildly basic methanolysis of 2-alkyl-substituted 6 gave α-hydroxyaldehydes 11 as monomer-dimer mixtures; similar treatment of the 2-aryl analogues afforded aryl (hydroxymethyl) ketones 12. Compounds 11 underwent Wittig reactions with methoxycarbonylmethylenetriphenylphosphorane to give high yields of γ-hydroxy-α,β-unsaturated esters 13, predominantly as the E-isomers. β-Monosubstituted vinylic sulfoxides 1 possessing a β-aryl group, and β-disubstituted vinylic sulfoxides 3 reacted with trifluoromethanesulfonic anhydride-sodium acetate in acetic anhydride to give 2-(phenylsulfenyl) acylals 14. These gave 2-phenylsulfenyl aldehydes 15 upon basic methanolysis, and the corresponding primary alcohols 16 on reduction with sodium borohydride. Reaction of both geometric isomers of enantiomerically pure vinylic sulfoxide 1o with TFAA gave racemic 6o as a mixture of diastereomers. Reaction of optically pure (E)- and (Z)-1p with trifluoromethanesulfonic anhydride-sodium acetate in acetic anhydride gave acylal 19 in 10.5 and 23% e.e., respectively.
The Use of Methoxy(phenyldimethylsilyl)methyl-lithium as a Formyl Anion Equivalent
Ager, David J.,Gano, James E.,Parekh, Shyamal I.
, p. 1256 - 1258 (2007/10/02)
Methoxy(phenyldimethylsilyl)methyl-lithium provides a new formyl anion equivalent which affords α-hydroxyaldehydes via an oxidative desilylation procedure.
1-N-alkyl-aminoglycoside-XK-88 derivatives and methods for their manufacture
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, (2008/06/13)
1-N-Alkyl-Aminoglycoside-XK-88 derivatives, valuable as antibacterial agents, are prepared by the reaction of an acid addition salt of the corresponding 1-N-unsubstituted-Aminoglycoside-XK-88 antibacterial derivative or of a 2"-N-alkanoyl-Aminoglycoside-XK-88-5 derivative in an inert solvent, preferably a protic solvent containing water, with one equivalent of a hydride-donor reducing agent and with at least one equivalent of an aldehyde. The 2"-N-alkanoyl-Aminoglycoside-XK-88-5 intermediates are prepared by the reaction of a partially neutralized acid addition salt of Aminoglycoside-XK-88-5 with an acylating agent, and isolating the 2"-N-alkanoyl-Aminoglycoside-XK-88-5.
1-N-alkyl-4,6-di-(aminoglycosyl)-1,3-diaminocyclitols, methods for their manufacture, methods for their use as antibacterial agents, and compositions useful therefor
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, (2008/06/13)
1-N-Alkyl-4,6-di-(aminoglycosyl)-1,3-diaminocyclitols, valuable as antibacterial agents, are prepared by treating an acid addition salt of a 4,6-di-(aminoglycosyl)-1,3-diamonocyclitol antibacterial agent in an inert solvent, preferably a protic solvent containing water, with one equivalent of a hydride donor reducing agent and with at least one equivalent of an aldehyde. The 1-N-alkyl-4,6-di-(aminoglycosyl)-1,3-diaminocyclitols are also prepared by treating the corresponding 1-N-acyl-4,6-di-(aminoglycosyl)-1,3-diaminocyclitol with an amide-reducing hydride reagent in an inert organic solvent. Other methods of preparing 1-N-alkyl-4,6-di-(aminoglycosyl)-1,3-diaminocyclitols include carrying out the foregoing processes with partially N-protected intermediates. Another useful process involves preparing a Schiff base of the 1-amino function of a partially N-protected 4,6-di-(aminoglycosyl)-1,3-diaminocyclitol followed by reduction of said Schiff base and removal of the N-protecting groups. Pharmaceutical compositions comprising 1-N-alkyl-4,6-di-(aminoglycosyl)-1,3-diaminocyclitols are described as well as the method of using said compositions to elicit an antibacterial response in a warm blooded animal having a susceptible bacterial infection.
