Study the reactions of fluoroalkanesulfonyl azides with N-alkylindoles

The reactions of fluoroalkanesulfonyl azides R_fSO₂N₃1 with N-alkylindoles 2 have been studied in detail. It was found that both solvent and the amount of the azides seriously affected the product distribution. 1 reacted with equimolar of 2 in ether or 1,4-dioxane affording 2-(N-substituted-indolinylidene)fluoroalkane sulfonylimines 3 as major product; While, treatment of 2 with 2 equiv. of 1 in ethanol, an unexpected product N-substituted-2-fluoroalkanesulfonimino-3-diazo-indolines 4 were obtained in good yield. The reaction mechanism was discussed.     

Unexpected sulfonylamino migration in the reactions of carbazole derivatives with fluoroalkanesulfonyl azides

The reactions of fluoroalkanesulfonyl azides 1 with carbazole derivatives have been studied in detail. At room temperature 1 reacted with 1,2,3,4-tetrahydrocarbazole 2 readily to afford ring-contraction spiroindole derivatives 3 together with an unexpected 4a-fluoroalkanesulfonylamino-1,2,3,4-tetra-hydrocarbazoles 4. However, in the case of 9-methyl-1,2,3,4-tetrahydrocarbazole 5, unexpected sulfonylamino migration occurred and a similar product 9-methyl-1-fluoroalkanesulfonylamino-2,3,4,9-tetrahydro-1H-carbazoles 6 were obtained as major products in moderate yields. These new products were fully characterized by spectral methods and single X-ray diffraction analyses. Possible mechanisms for these reactions were proposed.     

Study on the reactions of fluoroalkanesulfonyl azides with N-alkylindoles

The reactions of fluoroalkanesulfonyl azides R_fSO₂N₃1 with N-alkylindoles 2 have been studied in detail. It was found that both solvent and the amount of the azides seriously affected the product distribution. 1 reacted with an equimolar amount of 2 in ether or 1,4-dioxane affording 2-(N-substituted-indolinylidene)fluoroalkane sulfonylimines 3 as major product; While, the treatment of 2 with two equivalent of 1 in ethanol afforded N-substituted-2-fluoroalkanesulfonimino-3-diazo-indolines 4 as an unexpected product in good yields. The reaction mechanism was discussed.     

Study on the reactions of fluoroalkanesulfonyl azides with pyrazine and its derivatives

The thermal reactions of fluoroalkanesulfonyl azides R_fSO₂N₃ with pyrazine and its derivatives are studied in detail. All the reactions involved the fluoroalkanesulfonyl nitrene intermediates R_fSO₃N: which was captured by pyrazine to give the pyrazinium N-fluoroalkanesulfonyl ylides C₄NH₄N⁺-⁻NSO₂R_f and hydrogen abstraction product R_fSO₂NH₂, but no corresponding N-pyrazinyl fluoroalkanesulfonyl amide derivatives R_fSO₂NHC₄N₂H₃ were isolated. Excess azides did not afford the bisN-ylide product R_fSO₂N⁻-⁺NC₄H₄N⁺-⁻NSO₂R_f.     

Study on the reactions of fluoroalkanesulfonyl azides with indole derivatives

The reactions of fluoroalkanesulfonyl azides 1 with different indole derivatives have been studied in detail. Treatment of 1 with equimolar amount of 1,3-dimethylindole 3 in 1,4-dioxane at room temperature afforded 2-(1,3-dimethyl-1,3-dihydro-indolinylidene) fluoroalkanesulfonylimines 5 in moderate to good yields. However, under the same reaction conditions, in the case of 1 with 1,2-dimethylindole 4, the corresponding 2-fluoroalkanesulfonyl (1,2-dimethyl-1H-indol-3-yl)-amide 6 was obtained in moderate yields. In addition, the reactions of 1 and indole 7 gave different products under different conditions. Possible mechanisms of these reactions were proposed.     

Reactions of fluoroalkanesulfonyl azides with pyrrole and its derivatives

The reactions of fluoroalkanesulfonyl azides with pyrrole and its derivatives were studied. The reaction proceeded smoothly under mild conditions to give the 3-(fluoroalkanesulfonamido) pyrroles in good yield. The electron donating groups on the pyrrole core accelerated the reaction, while the electron withdrawing groups decelerated it. All the products were fully characterized by spectrum methods, and one of the products was further confirmed by X-ray diffraction analysis. A possible reaction mechanism for these reactions was proposed.     

氟烷基磺酰叠氮的化学反应研究

氟烷基磺酰叠氮可以与一系列亲核试剂,烯胺、烯基硅醚等富电子烯烃进行独特的反应,并且能够在温和条件下将含氟基团引入到有机分子中。     

Study on the reactions of fluoroalkanesulfonyl azides with cycloalkenyl ether and aryl ynamines

The reactions of fluoroalkanesulfonyl azides 1 with some electron-rich compounds have been studied in detail. Cycloalkenyl vinyl ethers reacted with 1 readily at 0 °C to give the corresponding ring-contraction N-fluoroalkanesulfonyl amidine analogues 3. In contrast, aryl ynamine generated in situ reacted with 1 affording fluorinated α-diazoamidines 9, which were decomposed slowly at room temperature to form [1-diethylamino-2-(4-nitro-phenyl)-2-oxo-eth-(Z)-ylidene]-fluoroalkanesulfinyl imine 10 with elimination of nitrogen gas. Possible mechanisms for these reactions were proposed.     

Unexpected conversion of alkyl azides to alkyl iodides and of aryl azides to N-tert-butyl anilines

In the presence of tert-butyl iodide, alkyl azides are converted into the corresponding iodides at room temperature, whereas, N-t-Bu anilines are obtained from aryl azides under the same experimental conditions. A mechanism is proposed to explain this unusual reactivity.     

Reactions of fluoroalkanesulfonyl azides with cyclic vinyl ethers

The addition reactions of fluoroalkanesulfonyl azides to dihydropyran or dihydrofuran were studied. These reactions do not give the corresponding N-fluoroalkanesulfonyl azilidines but N-fluoroalkanesulfonyl-tetrahydropyranon-2-imines or N-fluoroalkanesulfonyl-tetrahydro-furano-2-imines. The reaction mechanism is discussed.     

Charge transfer complexes of some anilides with nitrobenzene derivatives as pi-electron acceptors

The charge transfer complexes formed between some anilides and pi-electron acceptors [picric acid, 2,4-dinitrophenol, 3,5-dinitrobenzoic aicd, 3,5-dinitrosalicylic acid and m-dinitrobenzene] are synthesized and characterized. Spectral characteristics and stability of the complexes are investigated and discussed in terms of donor molecular structure, pi-acceptor electron affinity, and solvent polarity. It is deduced that the complexes are mainly of the n-pi* and pi-pi* type where the ground state wave function can be described primarily by the non-bonding structure. The optimum conditions favouring the formation of the coloured complexes are extensively studied for the microdetermina-tion of anilides derivatives in pharmaceutical drugs using nitrobenzene as acceptor; the molecular structure was found to be 1:1 (D:A). Beer's law is obeyed up to 23.0, 18.60 and 16.0 micrograms ml-1 for p(OH), p-(OCH3), and p-N(CH3)2, respectively.     

Oxidative reactions of tetrahydrobenzimidazole derivatives with N-sulfonyloxaziridines

An investigation of the utility of N-sulfonyloxaziridines to effect the oxidative rearrangement of tetrahydrobenzimidazoles to spiro fused 5-imidazolones is reported. In addition to the anticipated rearrangement manifold, it was found that 2-amino substituted derivatives afford products resulting from rearrangement, or alternatively from addition of methanol or water depending on the nature of the N-substituents and reaction conditions.     

Unexpected formation of N,N-disubstituted formamidines from aromatic amines, formamides and trifluoroacetic anhydride

An intriguing selectivity towards the formation of the formamidine was observed upon the reaction of an amine with sodium hydride and trifluoroacetic anhydride in dimethyl formamide. Various aromatic amines were reacted with a series of N,N-disubstituted formamides as a solvent under the influence of trifluoroacetic anhydride to thoroughly probe this behaviour. A trend in selectivity is discussed and a proposed mechanism for the reaction is also presented.     

Addition reactions of fluoroalkanesulfonyl azides to [60] fullerene under thermal or microwave irradiation condition

The reactions of [60] fullerene with excess fluoroalkanesulfonyl azides R_fSO₂N₃ in o-dichlorobenzene under thermal or microwave irradiation condition afforded monoadduct opened [5,6]-bridged azafulleroids. While, similarly treatment of 2,2,2-trifluoroethyl azides CF₃CH₂N₃ with C₆₀ gave two monoadducts, i.e., opened [5,6]-bridged azafulleroids, closed [6,6]-bridged Aziridino-fullerene, and some multi-addition product. A general mechanism for these addition reactions was proposed.     

Reactions of fluoroalkanesulfonyl azides with vinyl ether and tetrakis(dimethylamino)ethylene

The reactions of fluoroalkanesulfonyl azides 1 with some electron-rich olefins have been studied. Alkyl vinyl ethers reacted with 1 readily at 0 °C or room temperature (RT) and did not give the corresponding N-fluoroalkanesulfonyl azilidines but 1-fluoroalkanesulfonyl-1,2,3-triazolines 3, which decomposed slowly at room temperature to form 1,4-fluoroalkanesulfonyl-2,5-alkoxyl-piperazines 4 with elimination of nitrogen gas. In contrast, more electron-rich alkene, tetrakis(dimethylamino)ethylene (TDAE) reacted with 1 affording N-fluoroalkanesulfonyl bis(dimethylamino)amidines 6 accompanying the release of N₂. Reaction mechanisms are discussed.     

Synthesis of indene derivatives via reactions of vinylidenecyclopropanes with the N-acyliminium cations generated from hydroxylactams

A novel route for the synthesis of 1H-indene derivatives via the reactions of vinylidenecyclopropanes (VCPs) with the N-acyliminium cations generated from hydroxylactams is described.     

Unexpected formation of tetrasubstituted 2,3-dihydrofurans from the reactions of beta-keto polyfluoroalkanesulfones with aldehydes

Catalyzed by piperidine, the reactions of beta-keto polyfluoroalkanesulfones with aromatic aldehydes afforded the unexpected tetrasubstituted 2,3-dihydrofurans in good yields, probably proceeding through the normal Knoevenagel condensation products. This reaction provided an efficient and novel method for the stereoselective synthesis of fluorine-containing tetrasubstituted trans-2,3-dihydrofurans.     

Sialylation reactions with N,N-dibenzylthiosialoside donor

A new sialyl donor, N,N-dibenzyl-protected p-toluenethiosialoside, was synthesized and its sialylation reaction was investigated. This reaction proceeded in a preactivation manner and preferred to provide β-anomeric coupling products. The β-selectivity was rationalized based on the assumption that N,N-dibenzylamino group could serve as an oriented group to activate the hydroxyl group of acceptor from β-face.     

Studies on the reactions of fluoroalkanesulfonyl azide with aromatic compounds

The thermal decomposition reactions of fluoroalkanesulfonyl azides R_fSO₂N₃ (1) in the presence of various substituted benzene X_nC₆H_6−n [X: CH₃ (n=1, 2, 4, 6), OCH₃ (n=1, 2), C₆H₅CH₂ (n=1), F, Cl, Br] were studied in detail. The N-aryl fluoroalkanesulfonyl amides [R_fSO₂NHC₆H_5−nX_n] were produced as the major products. The ortho/para ratio resembled that of an electrophilic aromatic substituted reaction. An ionic π- or σ-complex was postulated as the intermediate for these reactions.     

Cobaloxime template reactions I. The formation of N-nitrosamines

The synthesis of a potent carcinogen, N-nitroso-N-methylaniline, employing a bis(dimethylglyoximato)cobaltate template is described. Carbon bonded N-methyleneaniline adducts of cobaloxime with pyridine, NO^-₂ or CN^- in the basal (sixth) coordination position of the cobalt atom were prepared and isolated. These cobaloxime methyleneaniline adducts were found to readily undergo nitrosation when treated with nitrous acid. The resulting N-nitrosamine adducts were characterized by IR, NMR and mass spectroscopy. Interesting trans effects of the basal substituents are noted. Final template reaction products were identified by thermal degradation and chemical cleavage with Cr²⁺.