Pyrrolidines nitro

Alicyclic hydroxamic acids undergo several specific oxidative cleavage reactions which may be of diagnostic or preparative value. In the pyrrolidine series compounds of type 66 have been oxidized with sodium hypobromite or with periodates to give y-nitroso acids (113). Ozonolysis gives the corresponding y-nitro acids. The related cyclic aldonitrone.s are also oxidized by periodate to nitroso acids, presumably via the hydroxamic acids.This periodate fission was used in the complex degradation of J -nitrones derived from aconitine. 

As discussed in Chapter 6, nitro compounds are converted into amines, oximes, or carbonyl compounds. They serve as usefid starting materials for the preparation of various heterocyclic compounds. Especially, five-membered nitrogen heterocycles, such as pyrroles, indoles, ind pyrrolidines, are frequently prepared from nitro compounds. Syntheses of heterocyclic compounds using nitro compounds are described partially in Chapters 4, 6 and 9. This chapter focuses on synthesis of hetero-aromadcs fmainly pyrroles ind indolesi ind saturated nitrogen heterocycles such as pyrrolidines ind their derivadves. 

Nitro compounds have been extensively used for synthesis of pyrrolidines as discussed in Chapter 4 on the Michael addidon and Chapter 8 on cycloaddidon. Tandem [2 + 4 /[2 + 3 ... 

Baker s yeast reducdon of y-nitroketones offers the corresponding chiral nitro alcohols, which areusefid bndding blocks for the synthesis of chiral naniral compounds. For example, opdcally acdve 2-subsdnited pyrrolidine can be prepared using the chiral nitro alcohol fEq. 10.751. ... 

In a related study, the reaction of the enamine, l,2-dihydro-3-(2-methoxymethyl-l-pyrrolidin-yl)naphthalene [from 3,4-dihydro-2(l//)-naphthalenonc and (S)-2-(methoxymethyl)pyrrolidine] with 2-aryl-l-nitroethenes gave, after hydrolysis, an 83 17 to 95 5 mixture of the (3S,YR)- and (1/ ,1 T )-nitro ketones31. 

Secondary amines can be added to certain nonactivated alkenes if palladium(II) complexes are used as catalysts The complexation lowers the electron density of the double bond, facilitating nucleophilic attack. Markovnikov orientation is observed and the addition is anti An intramolecular addition to an alkyne unit in the presence of a palladium compound, generated a tetrahydropyridine, and a related addition to an allene is known.Amines add to allenes in the presence of a catalytic amount of CuBr " or palladium compounds.Molybdenum complexes have also been used in the addition of aniline to alkenes. Reduction of nitro compounds in the presence of rhodium catalysts, in the presence of alkenes, CO and H2, leads to an amine unit adding to the alkene moiety. An intramolecular addition of an amine unit to an alkene to form a pyrrolidine was reported using a lanthanide reagent. 

Naturally occurring and synthetic polyhydroxylated pyrrolidine and piperidines have recently received considerable attention due to their biological activities. Barco has used tandem Michael-Henry reactions to synthesize 2-hydroxymethyl-3-hydroxy-4-nitro-pyrrolidines, from which the nitro group is removed to give the natural product, trans 2-hydroxymethyl-3-hy-droxypyrrolidine (Eq. 7.72).91... 

Since Huisgen s definition of the general concepts of 1,3-dipolar cycloaddition, this class of reaction has been used extensively in organic synthesis. Nitro compounds can participate in 1,3-dipolar cycloaddition as sources of 1,3-dipoles such as nitronates or nitroxides. Because the reaction of nitrones can be compared with that of nitronates, recent development of nitrones in organic synthesis is briefly summarized. 1,3-Dipolar cycloadditions to a double bond or a triple bond lead to five-membered heterocyclic compounds (Scheme 8.12). There are many excellent reviews on 1,3-dipolar cycloaddition, in particular, the monograph by Torssell covers this topic comprehensively. This chapter describes only recent progress in this field. Many papers have appeared after the comprehensive monograph by Torssell. Here, the natural product synthesis and asymmetric 1,3-dipolar cycloaddition are emphasized.630 Synthesis of pyrrolidine and -izidine alkaloids based on cycloaddition reactions are also discussed in this chapter. 

Secondary aliphatic amines, such as diethylamine, pyrrolidine or piperidine, react with the electron-poor nitrate ester 2-(trifluoromethyl)-2-propyl nitrate (369) under neutral conditions to afford the corresponding W-nitro derivatives 370412. 

In non-polar solvents many aminolysis reactions show a third-order dependence on the amine, B. This may be explained by catalysis of leaving-group departure by hydrogen-bonded homoconjugates, BH+B. Evidence for this pathway has been adduced from studies of the reactions of some nitro-activated (9-aryl oximes (7) with pyrrolidine in benzene, chlorobenzene, and dioxane, and with piperidine and hexylamine in cyclohexane. The third-order dependence on amine of the reaction of 2,6-dinitroanisole with butylamine in toluene and toluene-octanol mixtures has been interpreted in terms of a mechanism involving attack by dimers of the nucleophile. ... 

Many synthetic methods have been reported for the pyrrolidine alkaloids, including procedures based on the Hofmann-Loffler reaction 132,412), the metal hydride reduction of pyrrolines 413,414), the a-alkylation of N-nitro-sopyrrolidine 412,415), the catalytic hydrogenation of pyrroles 133), the reductive amination of 1,4-diketones 25,138), the direct alkylation of 1-methoxy-carbonyl-3-pyrroline 416), the versatile synthesis from the Lukes-Sorm dilac-... 

The reaction of zinc, copper or lithium enolates of a-substituted -lactones with chiral nitro enamines, e.g., 2-methoxymethyl-l-(2-nitro-l-alkenyl)pyrrolidine, affords a,a-disubstituted <5-lactones of S configuration with high enantiomeric excesses (82 to 96 %)22,23. 

To rationalize the 5 selectivity, a cyclic transition state model has been proposed which involves the selection of the Re-face of the enolate by the Re-face of the nitro enamine and includes a coordination between the metallic cation and the nitrogen atom of the pyrrolidine ring23. 

Die 1-Aminierung mit O-Diphenylphosphinyl-hydroxylamin und Natriumhydrid in 1-Methyl-2-oxo-pyrrolidin ist sowohl fur wasserlosliche als auch fur wasserunlosliche Imidazole geeignet. Auch hier werden die Produkte iiblicherweise iiber die 1-Benzylidenamino-imidazole ge-reinigt. Auf diese Weise werden 1-Amino-611, l-Amino-4-nitro-611, l-Amino-2-methyl-4-ni(ro-611, l-Amino-2-methyl-61s und l-Amino-2-phenyl-imidazol678 hergestellt. 

Mit Zinkchlorid als Lewissaure in Acetanhydrid cyclisieren 1 -(2-Nitro-phenyl)-pyrrolidine beira Erhitzen. Dabei wird gleichzeitig in /J-Stellung oxidiert93 ... 

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