Oxime Acetates Research Articles

Internal Oxidant-Triggered Aerobic Oxygenation and Cyclization of Indoles under Copper Catalysis.

A concise synthesis of pyrazolo[1,5-a]indole derivatives by copper-catalyzed aerobic oxygenation and cyclization of indoles with oxime acetates is described. This protocol represents an elegant example of N-1, C-2, and C-3 tri-functionalization of indoles in one-pot. Mechanistic studies indicate the reaction proceeds through a radical procedure. Oximes as an internal oxidant have been demonstrated to be a driver to initiate aerobic oxidation, which provides a new oxidative pattern for C-H functionalization even with high atom- and step-economy.

Synthesis, Crystal Structure, and Catalytic Property of a Copper(II) Complex Derived From 2-Hydroxy-5-Methoxybenzaldehyde Oxime

With a bidentate Schiff base ligand 2-hydroxy-5-methoxybenzaldehyde oxime (HL) and copper acetate, a polynuclear copper(II) complex was prepared and characterized by elemental analysis, IR spectroscopy, and X-ray structure determination. The complex crystallizes in the orthorhombic space group Pbca with unit cell dimensions a = 7.5094(7) Å, b = 6.5131(7) Å, c = 33.081(3) Å, V = 1618.0(3) Å3, Z = 4, R1 = 0.0628, and wR2 = 0.1194. Single-crystal X-ray diffraction analysis reveals that the Cu atom is coordinated by two imino N, two phenolate O, and two oxime O atoms from two Schiff base ligands, in an octahedral coordination. Catalytic oxidation of the complex on some olefins was performed.

Cu-Catalyzed Three-Component Cascade Annulation Reaction: An Entry to Functionalized Pyridines.

A concise copper-catalyzed N-O bond cleavage/C-C/C-N bond formation procedure has been described for the synthesis of multisubstituted pyridines. Various oxime acetates, activated methylene compounds, and a wide range of aldehydes bearing aryl, heteroaryl, vinyl, and trifluoromethyl groups were employed to provide the tri- or tetrasubstituted pyridines with flexible substitution patterns. Moreover, this method features inexpensive catalysts, no need for extra oxidant, and high step-enconomy, which make it pratical and attractive.

ChemInform Abstract: Practical Synthesis of Pyrazoles via a Copper‐Catalyzed Relay Oxidation Strategy.

Abstract1,3‐ and 1,3,4‐substituted pyrazoles are smoothly formed via a one‐pot cascade reaction under aerobic conditions with oxime acetates.

ChemInform Abstract: A Simple Route to Functionalized Δ1‐Pyrrolines.

AbstractThe cupric acetate or ferric chloride mediated cyclizations of unsaturated oxime acetates lead to vinyl‐ or chloroalkyl‐substituted pyrrolines in moderate to good yields.

Inside Cover: Copper-Catalyzed Coupling of Oxime Acetates with Sodium Sulfinates: An Efficient Synthesis of Sulfone Derivatives (Angew. Chem. Int. Ed. 16/2014)

Upon treatment with a Cu catalyst oxime acetates can be converted into sulfonylvinylamine products, which will further transform into useful β-ketosulfones upon hydrolysis with H2O. H. Jiang et al. describe in their Communication on page 4205 ff. how the oxime acetates act as both the substrate and oxidant, thus giving the process an environmentally friendly character. The background shows the ancient Chinese symbol “The Eight Trigrams” to indicate the harmony between humans and nature, which is also the purpose of green chemistry.

Copper‐Catalyzed Coupling of Oxime Acetates with Sodium Sulfinates: An Efficient Synthesis of Sulfone Derivatives

AbstractSulfone derivatives are important synthetic intermediates. However, the general method for their preparation is through traditional coupling reaction: the alkylation of sodium sulfinates with phenacyl halides. Based on our previous work on sodium sulfinates and oxime acetates, we herein report a novel method for sulfone derivatives by oxidative coupling with sodium sulfinates and oxime acetates using copper as catalyst. The sulfonylvinylamine products could be formed in excellent yields. Upon hydrolysis by silica gel in CH2Cl2, β‐ketosulfones could also be efficiently constructed. Various sulfonylvinylamines and β‐ketosulfones were obtained in good to excellent yields under the optimized reaction conditions. Mechanistic studies indicated that this transformation involved copper‐catalyzed NO bond cleavage, activation of a vinyl sp2 CH bond, and CS bond formation. The oxime acetates act as both a substrate and an oxidant, thus the reaction needs no additional oxidants or additives.

Copper‐Catalyzed Coupling of Oxime Acetates with Sodium Sulfinates: An Efficient Synthesis of Sulfone Derivatives

Sulfone derivatives are important synthetic intermediates. However, the general method for their preparation is through traditional coupling reaction: the alkylation of sodium sulfinates with phenacyl halides. Based on our previous work on sodium sulfinates and oxime acetates, we herein report a novel method for sulfone derivatives by oxidative coupling with sodium sulfinates and oxime acetates using copper as catalyst. The sulfonylvinylamine products could be formed in excellent yields. Upon hydrolysis by silica gel in CH2 Cl2 , β-ketosulfones could also be efficiently constructed. Various sulfonylvinylamines and β-ketosulfones were obtained in good to excellent yields under the optimized reaction conditions. Mechanistic studies indicated that this transformation involved copper-catalyzed N-O bond cleavage, activation of a vinyl sp(2) C-H bond, and C-S bond formation. The oxime acetates act as both a substrate and an oxidant, thus the reaction needs no additional oxidants or additives.

Efficient access to 1H-indazoles via copper-catalyzed cross-coupling/cyclization of 2-bromoaryl oxime acetates and amines

A novel synthesis of 1H-indazoles via copper-catalyzed cross-coupling/cyclization of 2-bromoaryl oxime acetates and amines is reported.

ChemInform Abstract: Rhodium‐Catalyzed Enantioselective Hydrogenation of Oxime Acetates.

Rh-catalyzed enantioselective hydrogenation of oxime acetates was first reported, which afforded a new approach for chiral amine synthesis.

Rhodium-Catalyzed Enantioselective Hydrogenation of Oxime Acetates

Rhodium-Catalyzed Enantioselective Hydrogenation of Oxime Acetates

Rhodium-Catalyzed Enantioselective Hydrogenation of Oxime Acetates

Rh-catalyzed enantioselective hydrogenation of oxime acetates was first reported, which afforded a new approach for chiral amine synthesis.

An efficient synthesis of polysubstituted pyrroles via copper-catalyzed coupling of oxime acetates with dialkyl acetylenedicarboxylates under aerobic conditions

A Cu-catalyzed [3+2]-type condensation reaction of oxime acetates and dialkyl acetylenedicarboxylates that provides highly substituted pyrroles under aerobic conditions is described. The newly formed pyrroles are easily employed for further transformations to prepare pyrrolo[2,1-a]isoquinoline skeletons.

Palladium‐Catalyzed CH Bond Acetoxylation: An Approach to ortho‐Substituted Hydroxy[2.2]paracyclophane Derivatives

AbstractThe palladium‐catalyzed direct CH bond acetoxylation of [2.2]paracyclophanes has been investigated. Various mono‐ and disubstituted [2.2]paracyclophanes were subjected to typical Sanford acetoxylation conditions. Oxime ethers, an oxime acetate, a pyridine, and a pyrazole with [2.2]paracyclophane cores underwent direct ortho‐acetoxylation in good to excellent yields using 1–5 mol% of palladium(II) acetate in combination with iodobenzene diacetate as oxidant. The reactions could be performed on a multigram scale, and the ortho‐acetoxylated [2.2]paracyclophanes were suitable for further functionalizations affording a hydroxy[2.2]paracyclophane derivative and a planar chiral benzoxazole.

Synthesis of N-containing drimane sesquiterpenoids from 11-dihomodriman-8α-ol-12-one

Beckmann reaction products of 11-dihomodriman-8α-ol-12-one oxime with Ac2O in pyridine, 86% H3PO4, p-TsCl in pyridine, and PCl5 in ether were investigated. It has been found that the major product from treatment of the oxime with Ac2O is the oxime acetate. Reaction of the oxime with 86% H3PO4 gave (1S,2S,4aS,8aS)-2,5,5,8a-tetramethyldecahydro-1H-naphtho[1, 2][5, 6]-3-methyl-4,5-dihydro[1, 2, 6]oxazine; with p-TsCl, (1S,2S,4aS,8aS)-2,5,5,8a-tetramethyldecahydro-1H-naphtho[1, 2][5, 6]-2-methyl-4,5dihydro[1, 3, 6]oxazine; with PCl5, a mixture of products containing 11-acetylamino- and 11-methylaminooxodrimenes that were isomeric at the double bond, norambreinolide, and a 1,3,6-oxazine.

ChemInform Abstract: The Photochemical Synthesis of Potential Pyrethroid Components by the Aza-di-π-methane Rearrangement of β,γ-Unsaturated Oxime Acetates.

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ChemInform Abstract: Extension of the Aza-di-π-methane Reaction to Stable Derivatives. Photochemical Cyclization of β,γ-Unsaturated Oxime Acetates.

The successful sensitized photochemical conversion of oxime acetates of some β,γ-unsaturated aldehydes and of one ketone into cyclopropane derivatives by the aza-di-π-methane (ADPM) rearrangement has been carried out. Thus, for example, the acetophenon-sensitized irradiation of the oxime acetate of 2,2-dimethyl-4,4-diphenylbut-3-enal affords the oxime acetate of 2,2-dimethyl-3,3-diphenylcyclopropanecarboxaldehyde in 86% yield and with a quantum yield of 0.12. The first report of the successful ADPM rearrangement with all-alkyl substitution is described.

ChemInform Abstract: Unexpected Influence of Monophenyl Substitution on the Photochemistry of β,γ-Unsaturated Oxime Acetates.

ChemInform Abstract: Unexpected Influence of Monophenyl Substitution on the Photochemistry of β,γ-Unsaturated Oxime Acetates.

ChemInform Abstract: Steric and Electronic Effects on the Photochemical Reactivity of Oxime Acetates of β,γ-Unsaturated Aldehydes.

A general synthesis of 5-substituted N-acetoxy 3,3-dimethyl-1-azapenta-1,4-dienes starting from 2-(1,3-dithian-2-yl)-2-methylpropanal is described. The influence of 5-phenyl, 4-phenyl, 5-cyclohexyl, 5-tert-butoxycarbonyl and 5,5-dicyclohexyl substitution on the outcome of the photochemical reactions of the oxime acetates of β, γ-unsaturated aldehydes has been studied with a view to proving or disproving the operation of a deactivating free rotor in the aza-di-π-methane rearrangement. The results obtained show that if the radical formed at C-5 can be stabilized by conjugation with an aryl group or by certain types of disubstitution then the aza-di-π-methane rearrangement takes place successfully. In any other situation the reaction fails. These results clearly show that the free rotor effect is not responsible for the failure of C-5 monosubstituted 1-aza-1,4-dienes to undergo the aza-di-π-methane rearrangement.

SYNTHESIS OF NOVEL INDOLO[3,2-c]QUINOLINES; ETHYL 3-CHLORO-9,11-DIMETHOXY INDOLO[3,2-c]QUINOLINE-6-CARBOXYLATE

-Carboline and its derivatives are significant due to their pharmacological importance. The synthesis of indolo[3,2-c]quinolines as a benzo analog of -carboline has been carried out via an oxime ether intermediate. Reaction of 2'-glyoxylic ester with hydroxylamine hydrochloride in the presence of sodium acetate afforded the oxime acetate in 82%. It was then treated with natrium and fluoro-2,4-dinitrobenzene in ethanol to give an orange solid of oxime ether acetate which is in subsequent treatment with a base yielded a pale yellow solid of indolo[3,2-c]carboline in 43%. Keywords: -carboline, oxime, indolo[3,2-c]quinoline.