PEG-SO_3H as catalyst for the Beckmann rearrangement and dehydration of oximes

Under mild conditions, conversion of a variety of ketoximes and aldoximes to their corresponding amides and nitriles proceeded in the presence of PEG-SO3H with high yields.

A Mild Oxidant for the Regeneration of Carbonyl Compounds from Oximes in Nonaqueous Condition

Dioxane-NO2 was employed to oxidize oximes to corresponding aldehydes and ketones in high yield in nonaqueous condition at room temperature. Thr reaction proved to be mild and selective.

The Effective Catalyst (Cobalt Salt/Lewis Acid) for Beckmann Rearrangement of Cycloalkanone Oximes to Lactams under Mild Conditions

The Beckmann rearrangement of cyclohexanone oxime was achieved by the combined use of cobalt salt and Lewis acids co-catalysts (each 10 mol%). Various combinations of cobalt salts and Lewis acids gave lactams in a satisfactory yield under mild conditions. This method makes it possible to reduce undesirable byproducts.

A novel catalytic method for the regeneration of carbonyl compounds from oximes using aluminum nitrate and NaBr as catalyst

A wide variety of aldoximes and ketoximes were regenerated to corresponding carbonyl compounds with Al（NO3）3·9H2O in presence of catalytic amounts of NaBr in CH2Cl2 at room temperature.

A Novel Ionic Liquid/water Biphasic System for the Preparation of Oximes

A variety of carbonyl compounds can be converted into oximes efficiently and conveniently in a novel ionic liquid/water bi-phasic system in the presence of sodium bicarbonate at ambient temperature. The ionic liquid 1-butyl-3-methyl imidazolium hexafluorophosphate [bmim]PF6 is immiscible with water or diethyl ether and can be easily recycled for reuse without noticeable droping in activity after separation of the products. The protocol is rapid, the yields are excellent, the method is simple and the ionic liquid can be reused.

A Novel Method for Beckmann Rearrangement of Oximes with Silica Sulfuric Acid under Mild Condition

Silica sulfuric acid in which sulfuric acid is immobilized on the surface of silica gel via covalent bond has been proved to be green catalyst for liquid-phase Beckmann rearrangement of oximes in dried dioxane at room temperature. Excellent conversion and selectivity were acquired in the Beckmann rearrangement of cyclohexanone oxime. The catalyst system was recycled and reused.

Photopolymerization Initiated with Bis-[O-(α-Methacryl)]-α,β-Dioximes and Tertiary Amines

Among sensitizing systems, the combination of benzophenone(BP) and tertiary amines(TA) has been deeply studied. Since the structure of O-acyl-oximes is similar to that of BP and their triplet state energies are nearly equal, we want to know whether the behavior of the photopolymerization initiated with O-acyl-oximes—TA system is the same as that of photopolymerization initiated with

Low Environmental Load Process for the Beckmann Rearrangement of Cycloalkanone Oximes by Bronsted Acid Catalyst with Cobalt Salts

Beckmann rearrangements of oximes to lactams often require harsh conditions and/or the use of large amounts of acid catalyst. To reduce the amount of Bronsted acid required, and to avoid the formation of a large amount of undesirable byproducts under mild reaction conditions, a low environmental load process was developed. Beckmann rearrangements of cyclohexanone oxime and cyclooctanone oxime were achieved using a combination of a Bronsted acid and cobalt tetra-fluoroborate hexahydrate. Various Bronsted acid catalysts (10 - 20 mol%) were used to obtain the corresponding lactams in high yields at 80℃.

Synthesis of Novel 1-Alkyl-2-chloro(alkoxy)-1H-indole 3-Carbaldehyde Oximes and Oxime-ethers(esters) Derivatives

A convenient synthesis of 1-alkyl-2-chloro-1H-indole-3-carbaldehyde oximes（5a―5d） and 1-alkyl-2-phenoxy-1H-indole-3-carbaldehyde oximes（6a―6d） from 2-indolone was completed via the Vilsmeier-Haack reac-tion,with N-alkylation and oximation as the key steps.An improved one-pot method for the synthesis of 1-alkyl-2-alkoxy-1H-indole-3-carbaldehyde oximes（7a―7h） from 1-alkyl-2-chloro-1H-indole-3-carbaldehydes（3a―3d） was described.The Williamson reactions and esterification reactions were performed and the oxime-ethers and oxime-esters were synthesized,respectively.The new synthesized compounds（3a―11d） were characterized by 1H NMR,IR,MS,and elemental analysis.

Synthesis, characterization, antioxidant and anticancer evaluation of some novel flavone-4-oximes

A series of novel flavone-4-oximes[1]were synthesized by the oximation of substituted flavones.The synthesized compounds were characterized by various spectroscopic methods including IR,MASS,NMR spectroscopy.Out of the 14 test compounds screened for their antioxidant activity,compounds such as JGS-VI(a N,N dimethyl benzaldehyde derivative)and JGSVII(a 3,4 dimethoxy benzaldehyde derivative)exhibited antioxidant activity comparable to that of ascorbic acid with its IC50 value at 30.01 Mm as standard following DPPH?method.Compounds such as JGS-II(a Para fluro benzaldehyde derivative),JGS-IV(a Para methyl benzaldehyde derivative)and JGS-V(a thiophene-2-aldehyde derivative)exhibited anti-oxidant activity among all the test compounds screened against ABTS[2]using Quercetin with its IC50 value at 50.24 Mm.

Synthesis, Crystal Structure and Biological Activites of Rotenone O-Alkyl Oximes

A series of rotenone O-alkyl oxime derivatives was designed and synthesized. Their structures were confirmed by elemental analyses, Fourier transform infrared（FTIR） and 1H NMR spectral studies, and the typical crystal structure of rotenone O-ethyl oxime（3b） was determined by X-ray diffraction. The preliminary biological activities of the new compounds were evaluated. The results of bioassays indicate that the title compounds exhibit moderate insecticidal and bactericidal activities. Among the synthesized compounds, compound 3q exhibited 90.0% mortality against M. separata at 1000 μg/mL. Compounds 3b and 3g exhibited both 90.0% inhibition rate against R. solani at 500 μg/mL, respectively.

A Practical and Efficient Procedure for Preparation of Oximes by Use of InCl_3

InCl3 catalyzes the reaction of hydroxylamine hydrochloride with a number of aldehydes and ketones under solvent free condition to afford an efficient method for the synthesis of oximes.*

A new oxidative pathway of nitric oxide production from oximes in plants

Nitric oxide(NO)is an essential reactive oxygen species and a signal molecule in plants.Although several studies have proposed the occurrence of oxidative NO production,only reductive routes for NO production,such as the nitrate(NO_(3)^(-))-upper-reductase pathway,have been evidenced to date in land plants.However,plants grown axenically with ammonium as the sole source of nitrogen exhibit contents of nitrite and NO3−,evidencing the existence of a metabolic pathway for oxidative production of NO.We hypothesized that oximes,such as indole-3-acetaldoxime(IAOx),a precursor to indole-3-acetic acid,are intermediate oxidation products in NO synthesis.We detected the production of NO from IAOx and other oximes catalyzed by peroxidase(POD)enzyme using both 4-amino-5-methylamino-2′,7′-difluorescein fluorescence and chemiluminescence.Flavins stimulated the reaction,while superoxide dismutase inhibited it.Interestingly,mouse NO synthase can also use IAOx to produce NO at a lower rate than POD.We provided a full mechanism for POD-dependent NO production from IAOx consistent with the experimental data and supported by density functional theory calculations.We showed that the addition of IAOx to extracts from Medicago truncatula increased the in vitro production of NO,while in vivo supplementation of IAOx and other oximes increased the number of lateral roots,as shown for NO donors,and a more than 10-fold increase in IAOx dehydratase expression.Furthermore,we found that in vivo supplementation of IAOx increased NO production in Arabidopsis thaliana wild-type plants,while prx33-34 mutant plants,defective in POD33-34,had reduced production.Our data show that the release of NO by IAOx,as well as its auxinic effect,explain the superroot phenotype.Collectively,our study reveals that plants produce NO utilizing diverse molecules such as oximes,POD,and flavins,which are widely distributed in the plant kingdom,thus introducing a long-awaited oxidative pathway to NO production in plants.This knowledge has essential implications for understanding signaling in biological systems.

Photoredox-neutral ring-opening pyridylation of cyclic oximes via phosphoranyl radical-mediated N-O/C-C bond cleavages and sequential radical-radical coupling

A novel photoredox-neutral ring-opening pyridylation of non-prefunctionalized cyclic oximes has been accomplished through phosphoranyl radical-mediated N-O/C-C bond cleavages followed by radicalradical coupling.This mild acid-,base-,and oxidant-free protocol provides highly site-selective and efficient access to distally pyridylated alkylnitriles,which could be scale-up synthesized and readily converted into skeletally diverse compounds.Notably,the oxidized ground-state photocatalyst generated via the SET oxidation of the highly reducing excited-state photocatalyst by cyanopyridines might initiate the following phosphoranyl radical-mediated deoxygenative process.

Copper（I）-Catalyzed Intramolecular N-N Coupling of Cyclopropyl O-Acyl Ketoximes： Synthesis of Spiro-fused Pyrazolin-5-ones

A convenient copper-catalyzed approach has been developed for the synthesis of substituted spiro-fused pyrazolin-5-ones from readily available cyclopropyl O-acyl ketoximes via an intramolecular N-N bond formation reaction. These catalytic reactions proceed in excellent yields with a broad scope.

Docking and 3D-QSAR studies of N-benzyl isatin oximes as JNK3 inhibitors

The c-Jun N-terminal kinase （JNK） is involved in a variety of important cellular processes and aberrant JNK activity is associated with many human diseases.The ligand-based and receptor-based alignment rules were used to build 3D-QSAR models for a series of N-benzyl isatin oximes JNK inhibitors. The best models were obtained for the receptor-based alignment with CoMSIA combining steric （S）, electrostatic （E）, and hydrogen bond donor （D） and hydrogen bond acceptor （A） fields （q2 = 0.759, r2 = 0.966, r2 pred = 0.703）. Based on the contour maps of RB CoMSIA model, some key structural factors responsible for inhibitory activity were investigated. Large groups at N-substituent or R6 position are preferred to interact with hydrophobic residues Ile70, Asp150, Ala151, Asn152 and Ser193. Electron-donating or hydrogen bond donor groups on the isatin ring would form polar and hydrogen bond with the negative-charged residue Glu147. In addition, electron-withdrawing groups or hydrogen bond acceptor group near the N-substituent would enhance inhibitory activity. The results are in good accordance and complementary to each other. The developed models could provide guidance in the rational design of more potent and selective JNK inhibitors.

Facile Synthesis of Thioamides via P2Ss-Mediated Beckmann Rearrangement of Oximes

A facile and efficient approach to the synthesis of secondary thioamides from ketoximes via Beckmann rearrangement has been established, using phosphorus pentasulfide as a dehydrating and thiating agent. It is also efficient for the preparation of primary thiobenzamide from benzaldoxime. This approach features simple-operation, easy-control and good to excellent yields.

Recent advances for the photoinduced C—C bond cleavage of cycloketone oximes

Nitriles are widely existed in many bioactive compounds,and they can be easily transformed into other functional groups.Therefore,the synthesis of nitriles under cyanide-free conditions is of significant importance.Recent advances for the synthesis of nitriles through photoinduced C—C bond cleavage of cycloketone oximes classified by the type of C—X bond forming are summarized.Various compounds possessing nitriles can be efficiently accessed via this method.

Silica Gel Supported Trifluoromethanesulfonic Acid Catalyzed Beckmann Rearrangement of Cyclohexanone Oxime in Liquid Phase

The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.

A Convenient Preparation of N-Alkyl-2,5-dihydroisoxazoles from O-Allyl Oximes

The organoselenium-induced ring-closure reaction of O-allyl oximes gave cyclic iminium salts, which reacted with Grignard reagents to produce N-alkyl-4-phenylselenoisoxazolidines. 2,5-Dihydroisoxazoles could be obtained in good yields by subsequent selenoxide syn-elimination.