- Preparation of cyclic prodiginines by mutasynthesis in pseudomonas putida kt2440
-
Prodiginines are a group of naturally occurring pyrrole alkaloids produced by various microorganisms and known for their broad biological activities. The production of nature-inspired cyclic prodiginines was enabled by combining organic synthesis with a mutasynthesis approach based on the GRAS (generally recognized as safe) certified host strain Pseudomonas putida KT2440. The newly prepared prodiginines exerted antimicrobial effects against relevant alternative biotechnological microbial hosts whereas P. putida itself exhibited remarkable tolerance against all tested prodiginines, thus corroborating the bacterium’s exceptional suitability as a mutasynthesis host for the production of these cytotoxic secondary metabolites. Moreover, the produced cyclic prodiginines proved to be autophagy modulators in human breast cancer cells. One promising cyclic prodiginine derivative stood out, being twice as potent as prodigiosin, the most prominent member of the prodiginine family, and its synthetic derivative obatoclax mesylate.
- Klein, Andreas Sebastian,Brass, Hannah Ursula Clara,Klebl, David Paul,Classen, Thomas,Loeschcke, Anita,Drepper, Thomas,Sievers, Sonja,Jaeger, Karl-Erich,Pietruszka, J?rg
-
p. 1545 - 1552
(2018/10/21)
-
- Scope and mechanism of a true organocatalytic beckmann rearrangement with a boronic acid/perfluoropinacol system under ambient conditions
-
Catalytic activation of hydroxyl functionalities is of great interest for the production of pharmaceuticals and commodity chemicals. Here, 2-alkoxycarbonyl- and 2-phenoxycarbonyl-phenylboronic acid were identified as efficient catalysts for the direct and chemoselective activation of oxime N-OH bonds in the Beckmann rearrangement. This classical organic reaction provides a unique approach to prepare functionalized amide products that may be difficult to access using traditional amide coupling between carboxylic acids and amines. Using only 5 mol % of boronic acid catalyst and perfluoropinacol as an additive in a polar solvent mixture, the operationally simple protocol features mild conditions, a broad substrate scope, and a high functional group tolerance. A wide variety of diaryl, aryl-alkyl, heteroaryl-alkyl, and dialkyl oximes react under ambient conditions to afford high yields of amide products. Free alcohols, amides, carboxyesters, and many other functionalities are compatible with the reaction conditions. Investigations of the catalytic cycle revealed a novel boron-induced oxime transesterification providing an acyl oxime intermediate involved in a fully catalytic nonself-propagating Beckmann rearrangement mechanism. The acyl oxime intermediate was prepared independently and was subjected to the reaction conditions. It was found to be self-sufficient; it reacts rapidly, unimolecularly without the need for free oxime. A series of control experiments and 18O labeling studies support a true catalytic pathway involving an ionic transition structure with an active and essential role for the boronyl moiety in both steps of transesterification and rearrangement. According to 11B NMR spectroscopic studies, the additive perfluoropinacol provides a transient, electrophilic boronic ester that is thought to serve as an internal Lewis acid to activate the ortho-carboxyester and accelerate the initial, rate-limiting step of transesterification between the precatalyst and the oxime substrate.
- Mo, Xiaobin,Morgan, Timothy D. R.,Ang, Hwee Ting,Hall, Dennis G.
-
supporting information
p. 5264 - 5271
(2018/04/24)
-
- Copper-catalyzed synthesis of thiazol-2-yl ethers from oxime acetates and xanthates under redox-neutral conditions
-
A novel copper-catalyzed annulation of oxime acetates and xanthates for the synthesis of thiazol-2-yl ethers with remarkable regioselectivity has been developed. Various oxime acetates, whether derived from aryl ketones or alkyl ketones, or natural product cores are suitable for this conversion. Unique dihydrothiazoles were also obtained when both reaction sites were methine. Mechanistic studies indicated that imino copper(iii) intermediates were involved. In addition, this protocol proceeded under redox-neutral conditions and did not require additives or ligands.
- Zhu, Zhongzhi,Tang, Xiaodong,Cen, Jinghe,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
-
supporting information
p. 3767 - 3770
(2018/04/17)
-
- Titania-Supported Gold Nanoparticles Catalyze the Selective Oxidation of Amines into Nitroso Compounds in the Presence of Hydrogen Peroxide
-
In this article, the catalytic activity of titania-supported gold nanoparticles (Au/TiO2) was studied for the selective oxidation of amines into nitroso compounds using hydrogen peroxide (H2O2). Gold nanoparticles deposited on Degussa P25 polymorphs of titania (TiO2) have been found to promote the selective formation of a variety of nitroso arenes in high yields and selectivities, even in a large-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions. Kinetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality. A Hammett-type kinetic analysis of a range of para-X-substituted aryl amines implicates an electron transfer (ET) mechanism (ρ=-1.15) for oxidation reactions with concomitant formation of the corresponding N-aryl hydroxylamine as possible intermediate. We also show that the oxidation protocol of aryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene and the in situ formed nitrosoarenes.
- Fountoulaki, Stella,Gkizis, Petros L.,Symeonidis, Theodoros S.,Kaminioti, Eleni,Karina, Athanasia,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
-
supporting information
p. 1500 - 1508
(2016/05/19)
-
- One-pot two-step sequential transformation: Highly efficient construction of o-2,3,5,6-tetrafluorobenzonitrile substituted oximes ethers
-
A practical variety of o-2,3,5,6-tetrafluorobenzonitrile substituted oximes ethers bearing broad functional groups were synthesized in moderate to good yields. The key highlight of this disclosure involving a one-pot two-step tandem procedure in aqueous media: the in situ formation of aryl aldehydes or ketones oximes followed by the SNAr reaction with pentafluorobenzonitrile via the high selective CF bond cleavage.
- Liu, Cuibo,Yin, Xuguang,Chang, Jing,Tang, Xiangyang,Zhang, Bin
-
p. 101 - 108
(2014/08/18)
-
- Oxidation of primary amines to oximes with molecular oxygen using 1,1-diphenyl-2-picrylhydrazyl and WO3/Al2O3 as catalysts
-
The oxidative transformation of primary amines to their corresponding oximes proceeds with high efficiency under molecular oxygen diluted with molecular nitrogen (O2/N2 = 7/93 v/v, 5 MPa) in the presence of the catalysts 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungusten oxide/alumina (WO3/Al2O3). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various alicyclic amines and aliphatic amines can be converted to their corresponding oximes in excellent yields. It is noteworthy that the oxidative transformation of primary amines proceeds chemoselectively in the presence of other functional groups. The key step of the present oxidation is a fast electron transfer from the primary amine to DPPH followed by proton transfer to give the α-aminoalkyl radical intermediate, which undergoes reaction with molecular oxygen and hydrogen abstraction to give α-aminoalkyl hydroperoxide. Subsequent reaction of the peroxide with WO3/Al2O3 gives oximes. The aerobic oxidation of secondary amines gives the corresponding nitrones. Aerobic oxidative transformation of cyclohexylamines to cyclohexanone oximes is important as a method for industrial production of ε-caprolactam, a raw material for Nylon 6.
- Suzuki, Ken,Watanabe, Tomonari,Murahashi, Shun-Ichi
-
p. 2301 - 2310
(2013/04/24)
-
- Europium(III) triflate-catalyzed Trofimov synthesis of polyfunctionalized pyrroles
-
The synthesis of polyfunctionalized pyrroles by reaction of a ketoxime with dimethyl acetylenedicarboxylate using europium(III) triflate as the catalyst is described. Copyright
- Madabhushi, Sridhar,Vangipuram, Venkata Sairam,Mallu, Kishore Kumar Reddy,Chinthala, Narsaiah,Beeram, China Ramanaiah
-
supporting information; body text
p. 1413 - 1416
(2012/07/13)
-
- Catalytic process for the ammoximation of carbonyl compounds
-
The present disclosure pertains to a process for preparing an oxime in which a carbonyl compound is reacted in the liquid phase with NH3 and H2O2 in the presence of a catalyst to form the corresponding oxime, wherein the catalyst comprises a catalytic component selected from the oxides of metals of group 5 and group 6. The use of a niobia catalyst is particularly preferred. The process according to the disclosure is suitable for the manufacture of numerous oximes, in particular cyclohexanone oxime.
- -
-
Page/Page column 3
(2011/08/08)
-
- Catalytic process for the ammoximation of carbonyl compounds
-
The present invention pertains to a process for preparing an oxime in which a carbonyl compound is reacted in the liquid phase with NH3 and H2O2 in the presence of a catalyst to form the corresponding oxime, characterised in that the catalyst comprises a catalytic component selected from the oxides of metals of group 5 and group 6. The use of a niobia catalyst is particularly preferred. The process according to the invention is suitable for the manufacture of numerous oximes, in particular cyclohexasone oxime.
- -
-
Page/Page column 4; 5
(2011/09/12)
-
- Oxidation of amines over alumina based catalysts
-
Amines were oxidized by molecular oxygen in the vapor phase at atmospheric pressure over alumina and silicotungstic acid/alumina catalysts. The study is focused on the influence of structure of amine and catalyst properties on the composition of the main reaction products and byproducts. Coating of γ-Al2O3 with silicotungstic acid or its semisalt can significantly enhance its catalytic activity in amine oxidation. The adsorption of amine on weak acidic sites of catalyst is essential for its oxidation to main reaction products. Cycloalkylamines are oxidized mainly to cyclic oximes (selectivity up to 64%) and Schiff bases of appropriate cycloalkanone and cycloalkylamine (selectivity up to 38%). Mainly nitriles (selectivity up to 55%) and appropriate Schiff bases (selectivity up to 54%) were observed in the oxidation products of primary alkylamines. Their molar ratio depends on the catalyst acidity and reaction conditions. 1,6-Hexanediamine is oxidized mainly to caprolactam (yield 48%) and other cyclic lactames and Schiff bases as well as to dinitrile (yield 13%).
- Rakottyay, Karol,Kaszonyi, Alexander,Vají?ek, Stanislav
-
experimental part
p. 33 - 41
(2010/08/22)
-
- Chlorination of oximes with aqueous H2O2/HCl system: Facile synthesis of gem-chloronitroso- and gem-chloronitroalkanes, gem-chloronitroso- and gem-chloronitrocycloalkanes
-
Chlorination of cyclic and linear ketone oximes with aqueous H 2O2/HCl in a two-phase dichloromethane-water system selectively affords gem-chloronitroso compounds in yields of up to 94%. One-pot oxidation of the resulting gem-chloronitroso compounds with peracetic acid, prepared in situ, gives gem-chloronitroalkanes and cycloalkanes in yields of up to 82%. The advantages of the method are that it is facile and environmentally benign and does not require gaseous chlorine. Georg Thieme Verlag Stuttgart.
- Terent'ev, Alexander O.,Krylov, Igor B.,Ogibin, Yuri N.,Nikishin, Gennady I.
-
p. 3819 - 3824
(2008/02/09)
-
- A new route to lactam precursors from cycloalkanes: Direct production of nitrosocycloalkanes or cycloalkanone oximes by using tert-Butyl nitrite and N-hydroxyphthalimide
-
Clean and selective: Nitrosation and oximation of cycloalkanes was achieved by treating them with tBuONO under Ar in the presente presence of a catalytic amount of N-hydroxyphthalimide (see scheme). The novel, clean nitrosation procedure uses halogen-free, relatively mild reaction conditions and results in good product selectivity (almost no organic byproducts) and high recovery of the catalyst.
- Hirabayashi, Tomotaka,Sakaguchi, Satoshi,Ishii, Yasutaka
-
p. 1120 - 1123
(2007/10/03)
-
- Process for producing organic compounds using nitrites
-
A process produces an organic compound by allowing (A) a compound capable of generating a free radical to react with (B) at least one of esters and salts of nitrous acid in the presence of a nitrogen-containing cyclic compound constitutively having a skeleton represented by following Formula (i) in its ring: wherein X is an oxygen atom or an —OR group, and wherein R is a hydrogen atom or a hydroxyl-protecting group. Examples of the nitrogen-containing cyclic compound are cyclic imide compounds having a cyclic imide skeleton represented by following Formula (I): wherein n is 0 or 1; X is an oxygen atom or an —OR group, and wherein R is a hydrogen atom or a hydroxyl-protecting group.
- -
-
-
- Amberlyst A-21 an excellent heterogeneous catalyst for the conversion of carbonyl compounds to oximes
-
Oximes can be efficiently obtained at room temperature by simply dissolving the appropriate carbonyl compounds and hydroxylamine hydrochloride, in ethanol, with Amberlyst A-21 as catalyst. Good yields of oximes are obtained, in very short reaction times, even with polifunctionalized substrates.
- Ballini, Roberto,Barboni, Luciano,Filippone, Paolino
-
p. 475 - 476
(2007/10/03)
-
- Synthesis, C-13 NMR, and X-ray crystal structure of N6,N9-octamethylenepurinecyclophane
-
The synthesis and structure determination of N6,N9-octamethylenepurine cyclophane by single crystal X-ray diffraction is reported.The cyclophane was prepared from 6-chloropurine and 8-aminooctanoic acid as starting materials.The aminooctyl fragment was first attached to N9 of 6-chloropurine by means of the Mitsunobu reaction and cyclization to the cyclophane effected by nucleophilic attack of the amino group at the C6 position and displacement of chloride ion.Reversing the reaction strategy did not result in formation of the cyclophane.Crystals of the cyclophane were monoclinic, P21/n, a = 9.620(3), b = 12.266(3), c = 11.994(2), Angstroem, β = 111.25(2) deg, Z = 4.Intensities were measured with a Nicolet P3 diffractometer and MoKα radiation at room temperature.The structure was solved by direct methods and refined to R = 0.0683, Rw = 0.0493 based on 1730 reflections.The molecule shows some strain, but bond lenghts and angles are normal.Attempts to relieve the strain are made by a small distortion of the purine rings and bending of the N6 and C8' atoms out of the planes to which they are attached (0.314(4), 0.459(5) Angstroem).Further, the N6,H6,C1' group is twisted by 30 deg from the pyrimidine plane and the torsion angles in the aliphatic chain are distorted from the idealized 60, 120, 180 deg (average, 13.6 deg; range 5.1-24.9 deg).These distortions result in some weakening of the ?-bonding in the adenine moiety. Key words: purinophane synthesis, nucleophilic aromatic substitution, conformational analysis, crystal structure.
- Bell, R. A.,Faggiani, R.,Hunter, H. N.,Lock, C. J. L.
-
p. 186 - 196
(2007/10/02)
-
