Arylnitroso Compounds Research Articles

Base-Mediated Tandem [3 + 2] Cycloaddition/Ring Openning Reaction of Arylhydrazonoyl Chlorides with Arylnitroso Compounds for Synthesis of Substituted Diazene Oxides.

A base-mediated tandem [3 + 2] cycloaddition/ring opening reaction of nitrilimines generated from arylhydrazonoyl chlorides with arylnitroso compounds has been developed. This protocol provides a novel and rapid approach for the synthesis of substituted azoxy compounds under mild conditions with moderate to good yields and a broad substrate scope.

Access to Fused Pyrroles from Cyclic 1,3-Dienyl Boronic Esters and Arylnitroso Compounds.

Complimentary to classical hydroboration and boron-Wittig reactions, a new, efficient access to cyclic 1,3-dienyl boronic esters has been developed via diene or triene metathesis. Subsequently, fused pyrroles were synthesized with a broad substrate scope from the reaction of cyclic 1,3-dienyl boronic esters with arylnitroso compounds using a one-pot hetero-Diels-Alder/ring contraction sequence.

Genetically Encoded Residue-Selective Photo-Crosslinker to Capture Protein-Protein Interactions in Living Cells

Summary The genetically encoded non-selective photo-crosslinkers suffer from unpredictable crosslinking sites and false positive interacting proteins, thus, the identification of protein interactions and mapping accurate interaction interfaces remain largely elusive in living systems. Here, we report genetically encoded, residue-selective protein photo-crosslinker enabling covalent crosslinking of the interacting proteins with proximal lysine, upon UV light activation in vitro and in living cells. Using this photo-crosslinker, we demonstrate a crosslinking strategy to capture protein-protein interactions with residue selectivity in a temporal-resolved manner. In addition, this crosslinking strategy produces the lysine-selective crosslinking site and predictable crosslinked peptide, which serve as the direct evidence for protein-protein interactions and facilitate mass spectrometry analysis. More importantly, this photo-crosslinker enables the capture of elusive enzyme-substrate interaction with directly interacting lysine and validation of acetylation site of the substrate. This strategy represents higher spatiotemporal resolution, accuracy, and reliability for investigating dynamic, transient, and weak protein-protein interactions in living systems.

A Dienyl Boronate‐Aryl Nitroso Ene Reaction Entry to C‐Pyrrolyl Nitrones and Subsequent Conversion to Isoxazolidines

AbstractA new cascade reaction to access C‐pyrrolyl nitrones en route to isoxazolidines is reported; a process that involves four successive steps, the first key step being an ene‐reaction of a 3‐methyl‐1,3‐dienylboronate ester with an aryl nitroso compounds to derive uncommon 1,3‐dipoles which react with various alkenes to access isoxazolidines. The scope and mechanism of the cascade sequence is discussed.

Copper-Assisted Amination of Boronic Acids for Synthesis of Bulky Diarylamines: Experimental and DFT Study.

Comparative investigation of copper-assisted oxidative and reductive amination showed that the latter was preferable for the synthesis of bulky diarylamines. DFT estimation of the mechanism of copper(I)-assisted reductive amination of boronic acids with aryl nitroso compounds was performed and possible active species were identified. DFT estimation of the steric penalty revealed that the barrier for the transmetalation step for the hindered nitroso compound was almost the same as that for the unsubstituted one, whereas a bulky group in the boronic acid increased the activation energy. A DFT study of the influence of the electronic properties of the substituents in both reactants on the activation energy revealed that the optimal combination for the synthesis of unsymmetrical diarylamines to provide better yields was an electron-rich aryl boronic acid and an electron-deficient nitroso compound. By using these helpful guidelines, a series of new bulky diarylamines were obtained and fully characterized.

Solid-Phase Synthesis of ɤ-Lactone and 1,2-Oxazine Derivatives and Their Efficient Chiral Analysis.

Derivatives of 3-methyl-3,6-dihydro-2H-1,2-oxazine-6-carboxylic acid prepared by regioselective hetero Diels-Alder reaction of arylnitroso compounds with sorbic acid were used for solid-phase synthesis of a library of derivatives that included modification of carboxylic group, dihydroxylation of double bond and cleavage of N-O bond. Derivatives of 2,3,4-trihydroxyhexanoic acid obtained from 3,6-dihydro-2H-1,2-oxazines after double bond dihydroxylation and N-O cleavage were used for simple and stereoselective formation of chiral lactones derived from 3,4-dihydroxydihydrofuran-2(3H)-one. The final compounds obtained as a mixture of stereoisomers were analyzed with use of chiral HPLC and SFC. HPLC analyses were not successful for all derivatives or required lengthy chromatography. On the other hand SFC afforded much shorter analyses and was effective for all studied derivatives. The method of synthesis and analysis is thus suitable for future study of stereoselective synthesis of lactones and other derivatives from single oxazine derivatives and application of high-throughput synthesis on solid-support and combinatorial chemistry.

Para-Selective Halogenation of Nitrosoarenes with Copper(II) Halides

The para-selective direct bromination and chlorination of nitrosoarenes with copper(II) bromide and chloride is reported. Under mild reaction conditions, a range of halogenated arylnitroso compounds are obtained in moderate to good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of a one-pot procedure to obtain the corresponding para-halogenated aniline- and nitrobenzene derivatives.

ChemInform Abstract: Use of in situ Generated Nitrosocarbonyl Compounds in Catalytic Asymmetric α‐Hydroxylation and α‐Amination Reactions

AbstractReview: [23 refs.

Use of In Situ Generated Nitrosocarbonyl Compounds in Catalytic Asymmetric α-Hydroxylation and α-Amination Reactions

Abstract Nitroso compounds are highly fascinating electrophiles as they are able to selectively transfer both the heteroatoms in a variety of oxidation reactions. Bench stable aryl-nitroso compounds are most extensively utilized for this purpose. However, the prominent success of aryl-nitroso chemistry is still immature because of the difficulty in the cleavage of N-aryl bond. Nitrosocarbonyl compounds with easily removable protecting groups (e.g. Boc and Cbz) on the other hand are more attractive reagents. They are highly reactive, easily manipulable, and readily available via the oxidation of N-protected hydroxylamines. However, the transient nature and incompatibility of the catalytic processes with their generation has incarcerated their use mostly in hetero-Diels–Alder and ene reactions. In this account we will summarize our efforts to utilize the nitrosocarbonyl compounds as a source of electrophilic oxygen and nitrogen in a variety of asymmetric carbon–heteroatom bond-forming reactions. The O- vs. N-selectivity can be tuned by switching reaction conditions. Thus, highly functionalized tertiary α-hydroxy and α-amino carboxylic acids, tertiary α-hydroxy phosphonic acid derivatives and β-amino alcohols were synthesized in high yields and high enantioselectivities using nitrosocarbonyl compounds as a source of electrophilic oxygen and nitrogen.

Kinetics and mechanism of the nitrosobenzene deoxygenation by trivalent phosphorous compounds

The reaction of aryl nitroso compounds with organic phosphines and phosphites in aerated media is a convenient non-photolytic procedure to generate aromatic nitroso oxides. The reaction rate constants and activation parameters of the key (for the proposed method of nitroso oxide generation) reaction of nitrosobenzene with tripenyl phosphite or para-substituted phosphines (4-RC6H4)3P (R = MeO, Me, H, F), as well as that of para-methoxynitrosobenzene with triphenylphosphine in acetonitrile were determined by kinetic spectrophotometry and chemiluminescence. A significant transfer of the electron density to the nitroso compound occurs in the transition state of the reaction as was revealed using the Hammett correlation analysis and DFT calculations in the M06L/6-311+G(d,p) approximation. The introduction of the electron-donor substituent MeO into the para-position of PhNO decreases the reactivity of the nitroso compound by two orders of magnitude. The reactivity of triphenyl phosphite in the oxygen atom transfer reaction is lower by two orders of magnitude compared to that of triphenylphosphine. In the case of the reactions of PhNO with phosphines, the apparent rate constant depends on the oxygen content in the reaction medium.

ChemInform Abstract: A Novel, Efficient Synthesis of N‐Aryl Pyrroles via Reaction of 1‐Boronodienes with Arylnitroso Compounds.

A one-pot hetero-Diels–Alder/ring contraction cascade is presented from the reaction of 1-boronodienes and arylnitroso derivatives to derive N-arylpyrroles in moderate to good yields (up to 82%).

A novel, efficient synthesis of N-aryl pyrroles via reaction of 1-boronodienes with arylnitroso compounds

A one-pot hetero-Diels-Alder/ring contraction cascade is presented from the reaction of 1-boronodienes and arylnitroso derivatives to derive N-arylpyrroles in moderate to good yields (up to 82%).

Chemoselective ligation of sulfinic acids with aryl-nitroso compounds.

Making a comeback: The inefficient condensation of sulfinic acid and aryl nitroso compounds has been transformed into a chemoselective process that converts sulfinic acid into stable cyclic sulfonamide analogues (see scheme). This ligation proceeds rapidly under aqueous conditions in high yield, and lays the groundwork for the development of sulfinic acid detection methods in biological systems.

Preparation of N-aryl-ketonitrone spin traps

Abstract The syntheses of seven N-aryl-C,C-dialkoxycarbonylnitrones 1–7, six of which were original, were achieved from the appropriate aryl-nitroso compounds. These ketonitrones were found to trap efficiently carbon-centred free radicals in aqueous media, yielding stable aminoxyl radicals whose EPR spectra lasted several days. The two penta-deuterated compounds 6 and 7 were also found to be efficient at trapping methoxyl radical. Their various spin adducts showed simple three line signals, very sensitive to the polarity of the environment. This study represents the very first use of linear ketonitrones as spin traps.

Synthesis and 1,3‐Dipolar Cycloaddition Reactions of N‐Aryl‐C,C‐dimethoxycarbonylnitrones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and 1,3‐dipolar cycloaddition reactions of N‐Aryl‐C, C‐dimethoxycarbonylnitrones

AbstractArylnitroso compounds 1–3 easily reacted with dimethyl bromomalonate to give the corresponding N‐aryl‐C,C‐dimethoxycarbonylnitrones (4–6). Treatment of C,C‐dimethoxycarbonyl‐N‐( 1‐naphthyl)nitrone (4) with acetylene compounds (dimethyl acetylenedicarboxylate, methyl 2‐butynoate or ethyl phenylpropiolate) caused 1,3‐dipolar cycloaddition to furnish the corresponding 1H‐benz[g]indolines (7a‐c). In a similar manner, the reactions of nitrones 5 and 6 with acetylene compounds afforded the corresponding indolines 9a‐c and 11a‐c together with 4‐oxazolines 13a‐c and 14a‐c.

Novel Aza and Oxa Wittig-Horner Reactions of Diethyl (1-Benzenesulfonyl)indol-2-yl Methyl Phosphonate

Aza and oxa Wittig-Horner reactions of diethyl (1-benzenesulfonyI)indol-2-yl methyl phosphonate with arylnitroso compounds and oxygen have been reported.

Synthesis and reactions of some nitrone derivatives

Arylnitroso compounds easily react as nucleophiles with conjugated azoalkenes to give α-(arylimino- N-oxide)hydrazones by their 1,4-addition to the azo-ene system. These adducts undergo an internal heterocyclization process with pyrazole ring formation to produce 1-alkoxycarbonyl- or 1-aminocarbonyl-3-methyl-4-(arylimino- N-oxide)-1 H-pyrazol-5(4 H)-ones stereoselectively in Z form by loss of an alcohol molecule. Deoxygenation of these compounds with triphenylphosphine affords 1-alkoxycarbonyl- or 1-aminocarbonyl-3-methyl-4-arylimino-1 H-pyrazol-5(4 H)-ones. Basic treatment with triethylamine of the same compounds leads to 3-methyl-4-(arylimino- N-oxide)-1 H-pyrazol-5(4 H)-ones by removal of the substituents on N(I) heteroatom of the pyrazole ring. Both deoxygenation and basic treatment of 1-alkoxycarbonyl- and 1-aminocarbonyl-3-methyl-4-(arylimino- N-oxide)-1 H-pyrazol-5(4 H)-ones have been realized sequentially, providing 3-methyl-4-arylimino-1 H-pyrazol-5(4 H)-ones. The same products were succesfully obtained by reversing the order of these processes.

Electrophilic amination of 2-azadienes

2-Azadienes 1 bearing a trialkylsilyloxy group on position 3 can be regarded as carboxylic acid synthons. Their cycloadditions with several classes of nitroso compounds have been studied in details as well as the transformation of the adducts into α-amino acids. This study showed that arylnitroso compounds such as nitrosobenzene reacted with 2-azadienes to give adducts that are potential precursors of α-N-arylamino acids. We have outlined an important limitation to the use of α-chloronitroso compounds. They are not compatible with highly functionalized dienes like 2-azadienes. On the other hand α-cyanonitroso and acylnitroso compounds reacted with azadienes to give adducts which were readily converted into α-amino acid derivatives.

Mechanistic Aspects of Molybdenum-Promoted Allylic Amination

The mechanism of molybdenum-mediated allylic amination by phenylhydro- xylamine has been probed through a variety of kinetics, trapping, and stoichiometric model reaction studies. Specifically, the amination of 2-methyl-2-hexene by (dipic)(HMPA)Mo(η 2 -PhNO) (1a, dipic=2,6-pyridine- dicarboxylate; HMPA=hexamethylphosphoric triamide) is found to be first order in (1a) and zeroth order in olefin and HMPA. Evidence for disso- ciation of nitrosobenzene from (1a) is provided by trapping of the lat- ter as a hetero-Diels-Alder adduct with 2,3-dimethylbutadiene and by exchange experiments of (1a) with free aryl nitroso compounds