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Nitriles nitrile oxides

On the other hand, conjugated nitroalkenes are very useful electron-poor alkenes, prone to act as nucleophilic acceptor, mainly in the Michael reaction (Berestovitaskaya et al., 1994) or in the Diels-Alder cycloaddition (Denmark and Thorarensen, 1996). Moreover, the nitro group can be easily turned into a respectable array of functional groups such as its reduction to a primary amine, replacement with hydrogen (Ballini et al., 1983 Ono, 2001), conversion into a carbonyl (Nef reaction) (Ballini and Petrini, 2004), and transformation into other important functionalities such as nitrile, nitrile oxide, oximes, hydroxylamines, and thiols (Colvin et al., 1979). [Pg.55]

Pyrroles from 1,4-dicarbonyl compounds and ammonia isoxazolines from olefins and nitrile oxides. [Pg.96]

Isocyanates are derivatives of isocyanic acid, HN=C=0, ia which alkyl or aryl groups, as weU as a host of other substrates, are direcdy linked to the NCO moiety via the nitrogen atom. StmcturaHy, isocyanates (imides of carbonic acid) are isomeric to cyanates, ROCMSI (nitriles of carbonic acid), and nitrile oxides, RCMSI—>0 (derivatives of carboxyUc acid). [Pg.446]

Dipolar cycloaddition reactions with azides, imines, and nitrile oxides afford synthetic routes to nitrogen-containing heterocycles (25—30). [Pg.246]

Phototransformation of pyridazine 1,2-dioxides sharply contrasts with that of pyridazine 1-oxides. Pyridazine 1,2-dioxide derivatives give 3a,6a-dihydroisoxazolo[5,4- f]isoxazoles (53) through postulated bisiminoxyl radicals. 3,6-Diphenylpyridazine 1,2-dioxide gives, besides the corresponding bicyclic derivative (53), 3-phenylisoxazole (54) and 4,5-diphenyl-furoxan (55). The last two products can be explained by generation of the nitrile oxide from the intermediate (53) with subsequent dimerization to the furoxan (55 Scheme 18) (79T1267). [Pg.13]

Dihydrofuran (376) and 2,5-dihydrofuran (377) react with nitrile oxides to give furo[2,3-6 ]isoxazoles (378) and furo[3,4-rf]isoxazoles (379), respectively, as cycloadducts. The double bonds of furan, pyrrole and thiophene also react when the nitrile oxide is generated in situ. Thus furan and benzonitrile oxide gave (380), and with 2-methyl-2-oxazoline the cycloadduct (381) was obtained (71AG(E)810). These and related cycloadditions are discussed in Chapter 4.36. [Pg.148]

In theory, three isoxazolines are capable of existence 2-isoxazoline (2), 3-isoxazoline and 4-isoxazoline. The position of the double bond may also be designated by the use of the prefix A with an appropriate numerical superscript. Of these only the 2-isoxazolines have been investigated in any detail. The preparation of the first isoxazoline, 3,5-diphenyl-2-isoxazoline, from the reaction of )3-chloro-)3-phenylpropiophenone with hydroxylamine was reported in 1895 (1895CB957). Two major syntheses of 2-isoxazolines are the cycloaddition of nitrile A-oxides to alkenes and the reaction of a,/3-unsaturated ketones with hydroxylamine. Since 2-isoxazolines are readily oxidized to isoxazoles and possess some of the unique properties of isoxazoles, they also serve as key intermediates for the synthesis of other heterocycles and natural products. [Pg.3]

The electronic structure of nitrile A-oxides may be represented as a resonance hybrid of the canonical structures (335a-e). The structure (335a) is commonly used to represent this reactive species. [Pg.66]

Nitrile A-oxides, under reaction conditions used for the synthesis of isoxazoles, display four types of reactivity 1,3-cycloaddition 1,3-addition nucleophilic addition and dimerization. The first can give isoxazolines and isoxazoles directly. The second involves the nucleophilic addition of substrates to nitrile A-oxides and can give isoxazolines and isoxazoles indirectly. The third is the nucleophilic addition of undesirable nucleophiles to nitrile A-oxides and can be minimized or even eliminated by the proper selection of substrates and reaction conditions. The fourth is an undesirable side reaction which can often be avoided by generating the nitrile A-oxide in situ and by keeping its concentration low and by using a reactive acceptor (70E1169). [Pg.66]

The rate of dimerization of nitrile A-oxides is strongly influenced by the nature of R. When R = Cl, Br, CO2 alkyl or COR, the nitrile A-oxide cannot be isolated nor obtained in solution for any appreciable time. Table 11 gives the approximate time required for complete dimerization of some nitrile A-oxides (335) to furoxans (336) in benzene solution at 18 °C (70E1169). Evidently, steric and electronic effects dramatically increase the stability... [Pg.66]

Table 11 Stability of Some Nitrile Af-Oxides, R—C=N—O, towards Dimerization to Furoxans <70EU69)... Table 11 Stability of Some Nitrile Af-Oxides, R—C=N—O, towards Dimerization to Furoxans <70EU69)...
Hi) Preparation of isoxazoles from nitrile N-oxides The reaction between a nitrile //-oxide and an alkyne is so facile that it is usually sufficient to leave an ether solution of the reactants at room temperature to obtain the desired isoxazole in good yield. The reaction is in general sensitive to the size of the substituent on the alkyne but not on the nitrile -oxide. In the case of poorly reactive alkynes, the difficulty may be overcome by generating the nitrile -oxide in situ and keeping its concentration low. [Pg.68]

Table 13 Isoxazoles from Nitrile iV-Oxides and Alkynes... Table 13 Isoxazoles from Nitrile iV-Oxides and Alkynes...
On the whole, the cycloaddition of alkynes to nitrile N-oxides is one of the most important routes to isoxazoles, but in spite of its potentially wide application, its synthetic utility is less than that of the corresponding reaction with alkenes for the following reasons. (1)... [Pg.68]

Table 14 Isoxazoles from Nitrile N-Oxides and C=C Dipolarophiles... Table 14 Isoxazoles from Nitrile N-Oxides and C=C Dipolarophiles...
This variation provides a regiospecific synthesis of isoxazoles with a great variety of substituents. The nitrile A-oxide does not react with the doubly activated methylene group in neutral or acidic medium, but under alkaline conditions the reaction proceeds exother-... [Pg.70]

A -Isoxazolines are readily available from the 1,3-dipolar cycloaddition of nitrile -oxides with alkenes and from the condensation reaction of ehones with hydroxylamine. Therefore, methods of conversion of -isoxazolines into isoxazoles are of particular interest and of synthetic importance. [Pg.78]

The thermal or photolytic fragmentation of furazans to nitriles and nitrile Af-oxides has been reported (73JOC1054, 75JOC2880). The irradiation of dimethylfurazan (419) in the presence of cyclopentene, and benzofurazan (420) in the presence of dimethyl acety-lenedicarboxylate, gave isoxazoline (421) and isoxazole (422), respectively, in good yields. The thermolysis of acenaphtho[l,2-c]furazan (423) in the presence of phenylacetylene gave isoxazole (424) in 55% yield. [Pg.81]

However, the thermolysis of diacylfuroxans (429) yielded two types of nitrile Af-oxides. An uncrowded diacylfuroxan such as (429a) rearranged to the a- acyloximino nitrile A-oxide (430) the diacylfuroxan with bulky substituents such as in (429b) gave rise to the half molecule acyl nitrile Af-oxide (431). Both types of nitrile Af-oxides (431) and (430) have been trapped with DMAD and hexafluoro-2-butyne to give isoxazoles in good yield. These reactions are shown in Scheme 97. [Pg.81]

The thermolysis of 5-substituted 1,3,2,4-dioxathiazole 2-oxides (432) also gave nitrile Af-oxides which were trapped with DMAD to give isoxazoles (433) (76JOC1296). [Pg.81]

Both 4,5-dimethylisoxazole and 3,4-dimethylisoxazole are formed on treatment of the sodium derivative of a-methylacetaldehyde with hydroxylamine hydrochloride. The two isomers can be separated by fractional distillation <62HC(17)1, p. 54). 4,5-Dialkylisoxazole or 3,4-dialkylisoxazole can be obtained as the sole reaction product from an appropriate nitrile iV-oxide and an appropriate vinyl acetate. [Pg.83]

Alkylarylisoxazoles can be obtained from the cycloaddition of nitrile Af-oxides to substituted alkynes or alkenes (Section 4.16.4.1.2(ii)), and from the condensation of the 1,4-dilithio oximes (358) with benzonitriles (72JHC183) or amides (78JOC3015). [Pg.84]


See other pages where Nitriles nitrile oxides is mentioned: [Pg.400]    [Pg.400]    [Pg.142]    [Pg.153]    [Pg.737]    [Pg.801]    [Pg.8]    [Pg.84]    [Pg.143]    [Pg.146]    [Pg.148]    [Pg.166]    [Pg.3]    [Pg.66]    [Pg.67]    [Pg.67]    [Pg.67]    [Pg.67]    [Pg.67]    [Pg.68]    [Pg.68]    [Pg.69]    [Pg.70]    [Pg.81]    [Pg.85]   
See also in sourсe #XX -- [ Pg.8 , Pg.105 ]




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1,3-Dipolar cycloadditions nitrile oxides + alkenes

1,3-dipolar cycloaddition aryl nitrile oxides

1,3-dipolar cycloaddition of nitrile oxide

1,3-dipolar cycloaddition reactions aliphatic nitrile oxides

1,3-dipolar cycloaddition reactions with nitrile oxides

1,4,2-Oxathiazoles nitrile oxides

1- Butene, 3-methoxyreaction with nitrile oxide

1.2.4- Oxadiazoles nitrile oxides

1.3- Dipolar cycloaddition reactions nitrile oxides

1.3- Dipoles nitrile oxides

2- Nitrosopyridine, reaction with nitrile oxides

4,5-dihydroisoxazole nitrile oxide

4- Dialkylamino but-3-en-2-one reaction with nitrile oxides

4-Dimethylaminopyridine , nitrile oxide

5- Benzoyloxy-2 -furanone, reaction with aryl nitrile oxides

5-Acetoxy-2 -furanone, formation reaction with aryl nitrile oxides

Achiral dipolarophiles, nitrile oxide cycloadditions

Acrylamides, nitrile oxide cycloadditions

Acrylates cycloaddition reactions with nitrile oxides

Addition of nitrile oxides

Aldehydes nitrile oxide intermolecular cycloadditions

Aldehydes nitrile oxide intramolecular cycloadditions

Aldehydes nitrile oxides

Aldoximes nitrile oxides from

Aldoximes oxidation, nitrile oxide generation

Aliphatic nitrile oxides

Alkenes 3+2] cycloaddition with nitrile oxide

Alkenes catalytic nitrile oxide reactions

Alkenes intramolecular reactions, nitrile oxides

Alkenes nitrile oxide cycloadditions

Alkenes nitrile oxides

Alkenes reaction with nitrile oxides

Alkynes reaction with nitrile oxides

Alkynes with nitrile oxide

Allylic alcohols nitrile oxide cycloadditions

Allylic ethers with nitrile oxides

Amines, oxidation to nitriles

Amino polyols, nitrile oxides

Applications of nitrile oxides

Aromaticity, nitrile oxide cycloadditions, dipolar

Aryl nitrile oxides

Aryl nitrile oxides, cycloaddition

Asymmetric reaction nitrile oxide addition

Asymmetric reactions nitrile oxide cycloadditions, diastereoselectivity

Asymmetric reactions nitrile oxides

Azirines nitrile oxides

Biotin nitrile oxide intramolecular cycloadditions

By cycloaddition of nitrile oxides

By the reaction of nitrile oxides

C-X-Y-Fragment (Nitrile Oxide on Solid Phase)

Carbohydrate alkenes, nitrile oxide

Carbohydrate alkenes, nitrile oxide cycloadditions

Carbohydrate derivatives, nitrile oxide

Carbohydrate derivatives, nitrile oxide cycloadditions

Carbonyl compounds nitrile oxide cycloadditions

Catalytic cycloadditions nitrile oxides

Chemoselectivity, nitrile oxide cycloadditions

Chiral auxiliaries, diastereoselectivity, asymmetric nitrile oxide cycloadditions

Compactin via nitrile oxide cyclization

Cyclization, radicals with nitrile oxides

Cycloaddition intramolecular nitrile oxide [INOC

Cycloaddition of nitrile oxides with alkenes

Cycloaddition reactions of nitrile oxides with alkenes

Cycloaddition with nitrile oxides

Cycloadditions Involving Nitrile Oxides

Cycloadditions of nitrile oxides

Diastereoselectivity nitrile oxide cycloadditions

Diisopropyl nitrile oxide cycloadditions, chiral

Diisopropyl nitrile oxides

Dipolar cycloadditions of nitrile oxides

Dipolar cycloadditions with nitrile oxides

Dipolar nitrile oxide-based

Dipolarophiles nitrile oxide cycloadditions

Dipole structures nitrile oxides

Electron-Deficient C2 Fragments (Cycloadditions Involving Azomethines, Nitrones, Nitrile Oxides, and Dienes)

Enantioselectivity nitrile oxide cycloadditions

Esters nitrile oxide cycloadditions

Ethers, vinyl reaction with nitrile oxides

External reagents nitrile oxides

Facial selectivity nitrile oxide cycloadditions

Five-membered rings nitrile oxide intramolecular cycloadditions

From nitrile oxides

Furans nitrile oxide intramolecular cycloadditions

Furoxans intramolecular nitrile oxide cycloadditions

Furoxans nitrile oxides

Furoxans thermolysis, nitrile oxide generation

Grignard reagents, nitrile oxide cycloadditions

Hydrogen bonding, nitrile oxide cycloadditions

Hydrogen peroxide nitriles, oxidation with

Hydrogenation of nitrile oxide cycloaddition product

Hydroxamic acid chlorides nitrile oxides from

Hydroximoyl halide, nitrile oxide generation

Hydroxy ketones, synthesis from nitrile oxides

Intermolecular cycloadditions achiral nitrile oxides/chiral olefins

Intermolecular cycloadditions achiral nitrile oxides/olefins

Intramolecular nitrile oxide cycloaddition

Intramolecular nitrile oxide cycloaddition reaction

Intramolecular nitrile oxide cycloaddition synthesis

Intramolecular nitrile oxide-olefin

Intramolecular nitrile oxide-olefin cycloaddition

Intramolecular reaction nitrile oxide cyclization

Isocyanates nitrile oxides

Isocyanates, addition from nitrile oxide

Isothiocyanates nitrile oxides

Isoxazole from nitrile oxides

Isoxazoles by a Consecutive 3CR of Acid Chlorides, Alkynes, and Nitrile Oxides

Isoxazoles from nitrile oxides

Isoxazoles, from alkenes and nitrile oxides cycloaddition

Isoxazoline compounds nitrile oxide cycloadditions

Isoxazolines synthesis via nitrile oxide cyclization

Kinetic data, nitrile oxide cycloadditions

Lactones nitrile oxide intramolecular cycloadditions

Lewis acids nitrile oxide cycloadditions

Macrocyclic compounds, nitrile oxide

Magnesium alkoxides, nitrile oxide

Maytansine synthesis via nitrile oxide cyclization

Mesityl nitrile oxide

Mesityl nitrile oxide, 1,3-dipolar cycloaddition

Nitrile /V-oxides

Nitrile AT-oxides

Nitrile Oxides Mukaiyama procedure

Nitrile Oxides acids

Nitrile Oxides and Nitriles

Nitrile Oxides from 1,2,4-oxadiazoles

Nitrile Oxides from furazans

Nitrile Oxides from furoxans

Nitrile Oxides from isoxazolines

Nitrile Oxides oxidative dehydrogenation

Nitrile Oxides, Imines, and Sulfides

Nitrile TV-oxides

Nitrile oxide addition

Nitrile oxide cyclization

Nitrile oxide cyclization intramolecular

Nitrile oxide cycloaddition

Nitrile oxide formation

Nitrile oxide precursor

Nitrile oxide, Benzo

Nitrile oxide, Carbamoyl

Nitrile oxide, Functionalized

Nitrile oxide, cycloaddition structure

Nitrile oxide, cycloaddition synthesis

Nitrile oxides

Nitrile oxides

Nitrile oxides 1,3-dipolar cycloadditions

Nitrile oxides 1,4,2,5-dioxadiazines

Nitrile oxides INOC reaction

Nitrile oxides achiral olefins, with chiral auxiliaries

Nitrile oxides aldol” reduction-hydrolysis

Nitrile oxides aldol” ring cleavage, intermediates

Nitrile oxides aldoximes

Nitrile oxides alkene chiral centeres

Nitrile oxides aminoalcohol ring cleavage

Nitrile oxides aryl-bridged

Nitrile oxides as 1,3-dipoles

Nitrile oxides catalytic reactions

Nitrile oxides chiral dipolarophiles

Nitrile oxides cyclizations

Nitrile oxides cycloadditions

Nitrile oxides defined

Nitrile oxides deoxygenation

Nitrile oxides diastereoselective

Nitrile oxides diastereoselectivity

Nitrile oxides dimerization

Nitrile oxides dipolar cycloaddition

Nitrile oxides dipole/dipolarophiles

Nitrile oxides double bonds

Nitrile oxides from 2 molecules)

Nitrile oxides from nitrolic acids

Nitrile oxides frontier orbitals

Nitrile oxides functional derivatives

Nitrile oxides furoxan thermolysis

Nitrile oxides industrial applications

Nitrile oxides intramolecular cycloadditions

Nitrile oxides isoxazoles

Nitrile oxides isoxazoline compounds

Nitrile oxides isoxazoline ring cleavage

Nitrile oxides isoxazoline synthesis

Nitrile oxides mechanism

Nitrile oxides mechanistic studies and calculations

Nitrile oxides natural products

Nitrile oxides nitromethyl compounds

Nitrile oxides olefin regioselectivity

Nitrile oxides oxide

Nitrile oxides polycyclic isoxazolines and furoxans

Nitrile oxides polyols

Nitrile oxides reduction

Nitrile oxides regioselectivity

Nitrile oxides relative reactivity

Nitrile oxides stereoselectivity

Nitrile oxides structural chemistry

Nitrile oxides synthesis applications

Nitrile oxides synthesis from

Nitrile oxides tandem reaction sequences

Nitrile oxides to olefins

Nitrile oxides tropones

Nitrile oxides with acrylates

Nitrile oxides, alkenyl

Nitrile oxides, alkenyl cyclization

Nitrile oxides, alkenyl intramolecular cycloaddition

Nitrile oxides, alkynyl

Nitrile oxides, chiral, diastereoselectivity

Nitrile oxides, cycloaddition reactions

Nitrile oxides, cycloaddition with electron-deficient dipolarophiles

Nitrile oxides, cycloaddition with from primary nitro compounds

Nitrile oxides, cycloaddition with furoxans

Nitrile oxides, cycloadditions with alkenes

Nitrile oxides, cycloadditions, furan

Nitrile oxides, cycloalkenyl

Nitrile oxides, dimerisation

Nitrile oxides, dipolar cycloaddition with

Nitrile oxides, furanylcyclization

Nitrile oxides, reaction with benzoquinones

Nitrile oxides, reactions

Nitriles N-oxides

Nitriles formation from nitrile oxides

Nitriles from nitrile oxides

Nitriles oxidation

Nitriles oxidative decyanation

Nitriles silver oxide

Nitriles via oxidative cleavage of alkenes

Nitriles, oxidative cleavage

Nitroalkanes nitrile oxide generation

Nitrones and nitrile oxides as 1,3-dipoles

Nitrones nitrile oxide intermolecular cycloadditions

Nitrones nitrile oxide intramolecular cycloadditions

Of nitrile oxides with alkenes

Of nitrile oxides with alkenes compounds

Olefins chiral nitrile oxides

Olefins nitrile oxide cycloadditions

Oxazolines => nitrile oxides

Oxidation of Amides, Hydrazides, and Nitriles

Oxidation of nitriles

Oxidation of nitriles and amines

Oxidation state nitriles)

Oxidative Addition of Nitriles

Oxidative nitriles

Oxidative nitriles

Oximes nitrile oxide intramolecular cycloadditions

Oximes reaction to form nitrile oxide

Paliclavine via nitrile oxide cyclization

Paraffins nitrile oxides from

Porphyrinic nitrile oxides

Reaction with nitrile oxides

Reactions of Nitrile Oxides

Regioselectivity nitrile oxide cycloadditions

Relative reactivity, nitrile oxide cycloadditions

Relative reactivity, nitrile oxide cycloadditions relativity

Sarkomycin via nitrile oxide cyclization

Sodium hypochlorite, nitrile oxide generation

Solvent effects, nitrile oxide cycloadditions

Stable nitrile oxides

Stereoselectivity nitrile oxide cycloadditions

Uracils reaction with nitrile oxides

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