Oxidation of heterocyclic nitrogen ylids to nitro heterocycles. Comparison of dimethyldioxirane with peracids

Oxidation of 3-amino-4-(4-chlorophenyl)furazan ( 1 ) and its phosphine imine derivative, 3-(4-chlorophenyl)-4-trioctylphosphiniminofurazan ( 3 ), with dimethyldioxirane (DMD) gave 3-(4-chlorophenyl)-4-nitrofurazan ( 4 ) as the exclusive product. However, the sulfilimine derivative, 3-(4-chlorophenyl)-4-dimethylsulfiliminofurazan ( 2 ), was converted by DMD to the sulfoximine, 3-(4-chlorophenyl)-4-dimethylsulfoximinofurazan ( 6 ). These results contrast dramatically with the oxidations of these compounds with peracids.     

The aromaticity of heterocycles containing the imine nitrogen

The method of predicting aromaticity based on simple Hückel calculations is applied to heterocyclic systems which contain the imine nitrogen. The necessary heteroatom integrals were determined from thermochemical data. Replacement of C by N in alternant systems produced no dramatic changes, but in nonalternants the effect can be large and unexpected as in the azapentalenes where interesting synthetic possibilities are suggested.     

Oxidation with p-(Methoxycarbonyl)perbenzoic acid 2. Oxidation of nitrogen heterocycles to the N-oxides

Conclusions We have examined the oxidation of various nitrogen heterocycles to the N-oxides with p-(methoxycarbonyl)perbenzoic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2337–2339, October, 1978.Part 1 [1].Deceased.     

Stereoselective alkylations of chiral nitro imine and nitro hydrazone dianions. Synthesis of enantiomerically enriched 3-substituted 1-nitrocyclohexenes

Dianions of chiral nitro imines (generated by a combination of LDA and s-BuLi) underwent diastereoselective alkylation with methyl, butyl, isopropyl, allyl, and methallyl iodides. In contrast to the behavior of simple metalloenamines, the most selective auxiliary contained no coordinating groups but did possess a large steric difference between the two substituents. The yield and selectivity of the alkylations were improved by the addition of HMPA or DMPU. The use of (S)-1-naphthylethylamine as the auxiliary afforded the R absolute configuration of the alkylation products. This stereochemical outcome could be rationalized by simple steric approach controlled alkylation in a conformationally fixed, internally coordinated dianion. A SAMP nitro hydrazone gave poorer yields and selectivities.     

Polycondensed nitrogen heterocycles. VI. Pyrrolo[3,4-b]-1,4-thiazine. A new heterocyclic ring system

This paper describes the synthesis of a new ring system, pyrrolo[3,4-b]-1,4-thiazine, obtained via H → III → IV.     

Biotransformations of drugs belonging to nitrogen heterocycles

The present review covers general aspects related to the metabolism of organic compounds, primarily, of biologically active azaheterocycles used as drugs. Compounds of this type occupy a dominant place among known drugs. Data on the main chemical processes determining the pathways of principal biotransformations, such as redox reactions, hydrolysis, alkylation, acylation, various conjugations, isomerizations, and condensations, are summarized. The metabolisms of heterocycles is considered based on the ring size of the substrate.     

Synthesis of heterocycles from molecular nitrogen as a nitrogen source

Nitrogen fixation is a very attractive process. We succeeded in nitrogen fixation using a TiCl₄‐ or Ti(O‐i‐Pr)₄‐Li‐TMSCl system. Nitrogen fixation proceeds at room temperature under 1 atmosphere pressure of nitrogen to give a mixture of titanium nitride complex 12 , titanium nitrogen complex 13 , and N(TMS)₄. Using the titanium nitrogen complexes 1 , various heterocycles were synthesized from the corresponding ketocarbonyl compounds. Nitrogen in air could be fixed using this method. The total syntheses of lycopodine and monomolin I were achieved from nitrogen in air as the nitrogen source. On the other hand, transmetalation of the nitrogen moiety of titanium nitrogen complexes 1 to a palladium complex was realized, and the non‐substituted anilines could be synthesized from ArX and N₂ in the presence of the palladium catalyst. Furthermore, amide could be synthesized from ArX, CO, and N₂ using the palladium catalyst.     

Oxidation and isomerism of thietane-containing heterocycles

Oxidation of 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-dione, 5(6)-nitro-1-(thiethan-3-yl)-benzimidazole, 2-methyl-4-nitro-1-(thiethan-3-yl)- and 5-bromo-2-methyl-4-nitro-1-(thiethan-3-yl)imidazoles was examined. Corresponding 1-oxothietan-3-yl- and 1,1-dioxothietan-3-yl derivatives were synthesized for the first time. Some factors affecting the quality of the final products and optimal conditions of the oxidation of thietanyl derivatives of pyrimidine-2,4(1H,3H)-dione, nitrobenzimidazole, and nitroimidazole were found. According to 1H NMR spectroscopy data, the obtained sulfoxides are mixtures of cis/trans isomers, the diastereomers ratio determined by the substituent at position 3 of thietane ring.     

The tert-amino effect in heterocyclic chemistry. Synthesis of spiro heterocycles

The tert-amino reaction effect was examined. A new method to synthesize spiro heterocycles is presented. It was shown that the "tert-amino effect" could be applied to the formation of spiro-fused heterocycles. The formation of spiro compounds proceeds in most cases in good yields in a one-pot reaction.     

Synthesis of diverse heterocyclic scaffolds via tandem additions to imine derivatives and ring-forming reactions

A novel strategy has been developed for the efficient syntheses of diverse arrays of heterocyclic compounds. The key elements of the approach comprise a Mannich-type, multicomponent coupling reaction in which functionalized amines, aromatic aldehydes, acylating agents, and π- and organometallic nucleophiles are combined to generate intermediates that are then further transformed into diverse heterocyclic scaffolds via a variety of cyclization manifolds. Significantly, many of these scaffolds bear functionality that may be exploited by further manipulation to create diverse collections of compounds having substructures found in biologically active natural products and clinically useful drugs. The practical utility of this strategy was exemplified by its application to the first, and extraordinarily concise synthesis of the isopavine alkaloid roelactamine.     

Oxidation of p-aminophenols and formal radical cyclization onto benzene rings: formation of benzo-fused nitrogen heterocycles

p-Iodophenol and its O-MOM-protected ether can be converted into iodoamines 2. These give cross-conjugated ketones 3 on oxidation with hypervalent iodides in the presence of methanol, and the ketones undergo radical cyclization. Exposure of the products to acid or sequential treatment with a Grignard reagent and acid effects rearomatization to produce benzo-fused nitrogen heterocycles 4.     

Electron density distribution in heterocyclic systems with two vicinal nitrogen atoms. III. Dipole moments of some alkyl,aryl, and nitro pyrazole derivatives

Dipole moments of 13 alkyl and aryl derivatives of pyrazole are determined. It is found that fundamentally it is the pyrazole ring that determines the values of these dipole moments. The phenyl group behaves as a weak electron donor with respect to the pyrazole ring. It is shown that under the action of powerful electron-accepting substituents, such as the nitro group, the electron cloud of the pyrazole ring is polarized toward the electron acceptor.For Part II see [1].     

Advanced in the synthesis of heterocyclic compounds from aliphatic nitro derivatives. A review

The literature on the synthesis of heterocyclic compounds from aliphatic nitro derivatives in the past decade has been summarized.Moscow State Textile Academy, 117918, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1336, October, 1994. Original article submitted October 6, 1994.     

Saturated nitrogen heterocycles. 11. Catalytic synthesis of 2-pyrrolidylalkanols

Furylakylamines have been catalytically converted into novel isomers of 2-pyrrrol-idylalkanols bearing a secondary alcohol group in the aliphatic chain, or a tert-butyl group attached to the heterocycle.For Communication 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1058–1061, August, 1988.     

Uranium(VI) sulfilimine complexes: a new class of nitrogen analogues of the uranyl ion

The compound tetraphenylphosphonium tetrachlorooxo-S,S-diphenylsulfiliminatouranium, [Ph4P][UOCl4(NSPh2)], has been prepared in high yield from [Ph4P][UOCl5] and [Ph2S=NSiMe3]. An X-ray structure of this compound shows that the uranium atom has a pseudooctahedral geometry with oxygen and nitrogen atoms in trans positions. The structure of the analogous phosphoriminato complex [Ph4P][UOCl4(NPPh3)] has been determined for comparison. Derivatization of the sulfide group shows that only a limited range of functionalization confers stability toward reduction. The emission spectrum of the first electronic excited state reveals a greatly reduced energy compared with that of the uranyl ion. This red shift in the transition is consistent with the weakening of the U-N bond relative to the U-O bond.     

Reactions of α-ketohydrazidoyl halides with some heterocyclic amines. Facile synthesis of arylazo derivatives of fused heterocycles with a bridgehead nitrogen atom

Arylazo derivatives of imidazo[2,1-b]thiazoles, imidazo[1,2-b]pyrazoles, imidazo[1,2-b]-s-triazoles, imidazo[1,2-a]pyrimidines, and imidazo[1,2-a]pyridines were obtained in good yields from α-keto hydrazidoyl halides and 2-aminothiazole, 5-aminopyrazole, 5-aminotriazole, 2-aminopyrimidine, and 2-aminopyridine, respectively (cf. Tables I and II). The structures of the products were assigned and confirmed on the basis of their elemental analyses, spectra, and alternate synthesis wherever possible.     

Decomposition of electron-excited molecules of molybdenum and tungsten phosphine hydride and phosphine nitrogen complexes

The kinetics and mechanism of photodehydrogenation of the phosphine hydride complexes MH₄L₄ (M = Mo, W; L are phosphine ligands) and the formation of coordinatively unsaturated species M_L4 were studied by the absorbance of long-wavelength bands with λ_max at 450–460 nm appeared in the absorption spectra of the photoproducts. The rate constants of the reactions of the coordinatively unsaturated M(DPPE)₂ species (M = Mo, W; DPPE = Ph₂PCH₂CH₂PPh₂) with molecular nitrogen in benzene were determined (k _W = 200 s⁻¹, k _Mo = 8700 s⁻¹). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 282–284, February, 2008.