- A Biocatalytic Synthesis of Heteroaromatic N-Oxides by Whole Cells of Escherichia coli Expressing the Multicomponent, Soluble Di-Iron Monooxygenase (SDIMO) PmlABCDEF
-
Aromatic N-oxides (ArN?OX) are desirable biologically active compounds with a potential for application in pharmacy and agriculture industries. As biocatalysis is making a great impact in organic synthesis, there is still a lack of efficient and convenient enzyme-based techniques for the production of aromatic N-oxides. In this study, a recombinant soluble di-iron monooxygenase (SDIMO) PmlABCDEF overexpressed in Escherichia coli was showed to produce various aromatic N-oxides. Out of 98 tested N-heterocycles, seventy were converted to the corresponding N-oxides without any side oxidation products. This whole-cell biocatalyst showed a high activity towards pyridines, pyrazines, and pyrimidines. It was also capable of oxidizing bulky N-heterocycles with two or even three aromatic rings. Being entirely biocatalytic, our approach provides an environmentally friendly and mild method for the production of aromatic N-oxides avoiding the use of strong oxidants, organometallic catalysts, undesirable solvents, or other environment unfriendly reagents. (Figure presented.).
- Petkevi?ius, Vytautas,Vaitekūnas, Justas,Taurait?, Daiva,Stankevi?iūt?, Jonita,?arlauskas, Jonas,??nas, Narimantas,Me?kys, Rolandas
-
supporting information
p. 2456 - 2465
(2019/01/25)
-
- Equilibrium of acyl transfer between pyridine N-oxides and their acylonium salts
-
Transfer of acyl groups from N-acyloxypyridinium salts to pyridine N-oxides in acetonitrile was studied. The equilibrium constants of acyl exchange were determined. These quantities vary in the range covering eight orders of magnitude, depending on the st
- Rubachenko,Schroeder,Chotii,Kovalenko,Red'ko,Lenska
-
p. 1241 - 1246
(2008/12/22)
-
- Acetyl exchange between pyridine N-oxides in acetonitrile solutions: An attempt to apply the Marcus equation to acetyl transfer
-
Forty-three (including eight identical) reactions of acetyl transfer from N-acetyloxypyridinium salts to pyridine N-oxides in acetonitrile solutions were studied. The rate constants k2 vary in the range 107-10-1 1 mol-1 s-1; the equilibrium constants K, in the range 107-10-7; the activation enthalpy ΔH≠, in the range 17-30 kJ mol-1; the activation entropy -ΔS≠, in the range 60-85 J mol-1 K-1; and the heat of reaction -ΔH0, within ±50 kJ mol-1. All reactions occur in a single stage by the concerted SN2 mechanism with a low degree of bond cleavage in the transition state. The rate and equilibrium of the acetyl exchange are satisfactorily described by the Bronsted equation. The quality of predicting the reactivity is substantially improved by introducing into the correlation equation a second parameter, the rates of identical reactions.
- Rybachenko,Schroeder,Chotii,Titov,Kovalenko,Leska,Grebenyuk
-
p. 1608 - 1615
(2007/10/03)
-
- Alpha-substituted pyrimidine-thioalkyl and alkylether compounds as inhibitors of viral reverse transcriptase
-
The subject invention relates to pyrimidine-thioalkyl and alkylether compounds of Formula (I) and pyrimidine-thioalkyl and alkylethers of Formula (IA), namely the compounds of Formula (I) where R 4 is selected from the group consisitng of --H or --NR 15 R 16 where R 15 is --H and R 16 is --H, C 1 -C 6 alkyl, NH 2 or R 15 and R 16 taken together with the --N form 1-pyrrolidino, 1-morpholino or 1-piperidino; and R 6 is selected from the group consisting of --H, or halo (preferably --Cl); with the overall proviso that R 4 and R 6 are not both --H. The compounds of Formula (IA) are useful in the treatment of individuals who are HIV positive being inhibitors of viral reverse transcriptase. STR1
- -
-
-
- Biotransformation of phenyl- and pyridylalkane derivatives in rat liver 9,000xg supernatant (S-9)
-
When phenylpropanes were incubated with phenobarbital-pretreated rat liver 9,000xg supernatant (S-9), oxidative hydroxylation occurred to give phenylpropanol (racemic), (1R, 2S)- and (1R, 2R)-phenylpropanediols, (2S)-hydroxyphenylpropanone. Incubation of pyridylethane and propane with S-9 afforded α-pyridylethanol and propanol, but those were optically inactive. During the incubation of 1-phenylpropanone, an asymmetric redox reaction simultaneously occurred to give (2S)-phenylpropanol, (1R, 2S)- or (1R, 2R)-phenylpropanediols and (2R)-hydroxyphenylpropanone. Acetylpyridines were enantioselectively reduced to afford α-pyridylethanols in high optical yields (94-98%ee). The oxidation of pyridylalkane was significantly inhibited by cytochrome P-450 inhibitor (SKF-525A), but reduction of acetylpyridines was not inhibited. Thus, cytochrome P-450 was found to be responsible for the oxidation of pyridylalkane, but not for the reduction of the ketone.
- Takeshita, Mitsuhiro,Miura, Masatomo,Unuma, Yukiko,Iwai, Sakiko,Sato, Izumi,Hongo, Takahiko,Arai, Toshie,Kosaka, Kazuhiro
-
p. 831 - 836
(2007/10/03)
-
- An Improved Synthesis of Homoproline and Derivatives
-
An improved, general synthesis of substituted homoprolines has been developed by using readily available substituted pyridines (1).A key step in this synthetic procedure involves the known conversion of pyridine-N-oxides to 2-cyanopyridines (3) in nearly quantitative yields.The resulting nitriles are hydrolyzed to the corresponding pyridine-2-carboxylic acids (4).Subsequent reduction of the aromatic ring with PtO2/H2 gives the homoprolines (5) in good yields as racemic cis isomers.This procedure also can be utilized for the preparation of 5,6-benzohomoprolines fromthe appropriate quinoline precursors.The N-tert-butyloxycarbonyl (Boc) derivatives of these amino acids (useful intermediates for peptide synthesis) were also prepared in good yields.
- Shuman, Robert T.,Ornstein, Paul L.,Paschal, Jonathan W.,Gesellchen, Paul D.
-
p. 738 - 741
(2007/10/02)
-
- New description of substituent effect on electronic spectra by means of substituent constants-VI. Ultraviolet spectra of 4-substituted pyridine N-oxides and blue shifted iodine bands of their EDA complexes with iodine
-
Electronic spectra of 4-substituted pyridine N-oxides and their EDA complexes with iodine were studied.The substituent effect on the near u.v. 1A1 intramolecular CT bands of the N-oxides and on the blue shifted iodine bands caused by CT complex formation are discussed in terms of a general equation, theoretically derived in order to describe the substituent effect on electronic spectra by means of substituent constants.The results are quite successful and supported by semi-empirical SCFMO-Cl calculations.Based on the results mentioned above, the character of n-? type N-oxide-iodine CT complexes is also examined.The complex formation constants(log K) and pKa values of the N-oxides correlate especially well, indicating that the CT interaction mechanism cannot be neglected in proton addition reactions such as hydrogen bonding and pKa values.
- Uno, Bunji,Kano, Kenji,Kaida, Naoki,Kubota, Tanekazu
-
p. 937 - 944
(2007/10/02)
-
- KINETICS OF THE N OXIDATION OF SOME COMPOUNDS OF THE PYRIDINE SERIES WITH PERBENZOIC ACID IN CHLOROFORM AND AQUEOUS DIOXANE
-
A comparative study of the kinetics of the N oxidation of 19 derivatives of the pyridine series with perbenzoic acid in choroform and aqueous dioxane at 20, 25, 30, and 35 deg C was made.The rate constants, the parameters of the Arrhenius equation, and the activation energies of the N oxidation of the indicated monoazines were determined.The scale of the reactivities of the derivatives of the pyridine series was calculated within the framework of the Pearson hard-soft acid-base concept.
- Lohkov, R.E.
-
p. 264 - 271
(2007/10/02)
-
