Synthesis ofN,N′-dialkylmethylenebis(nitramines) fromN-alkylsulfamates

Symmetrical and unsymmetricalN,N′-dialkylmethylenebis(nitramines) were obtained fromN-alkylsulfamates by condensation with formaldehyde and subsequent nitration. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1085–1087, June, 2000.     

Silylation of γ,γ-bis(alkoxycarbonyl)-substituted aliphatic nitro compounds: synthesis of N,N-bis(trimethylsilyloxy)aminocyclopropanes*

Silylation of ,-bis(alkyloxycarbonyl)--aryl- and ,-bis(alkyloxycarbonyl)--alkyl-substituted aliphatic nitro compounds proceeds stereoselectively to give the corresponding N,N-bis(trimethylsilyloxy)aminocyclopropanes in high yields. These compounds can be used as synthetic equivalents of nitrosocyclopropanes.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-nitro-<Emphasis Type="Italic">N</Emphasis>′-(trimethylsilyl)carbodiimide

Nitration of N,N′-bis(trimethylsilyl)carbodiimide with N₂O₅ or (NO₂)₂SiF₆ afforded N-nitro-N´-(trimethylsilyl)carbodiimide, the first representative of N-nitro carbodiimides. Its further nitration led to the release of CO₂, which is presumably formed in the course of N,N´-dinitrocarbodiimide decomposition. The reactions of N-nitro-N´-(trimethylsilyl)carbodiimide with nucleophiles take place both at the tri methylsilyl group (for example, with NH₃) to give nitrocyanamide salts and at the carbodiimide C atom (for example, with Et₂NH) to give the corresponding nitroguan idines.     

Reaction of the Ruppert-Prakash reagent with perfluorosulfonic acids

A new property of Me₃SiCF₃ to undergo C-F bond activation upon interaction with perfluorosulfonic acids is described. The reaction is catalyzed by titanium tetrachloride and affords difluoromethyl perfluorosulfonates in good yields.     

Diffractive dissociation of deuterons and exotic nuclei <Superscript>6</Superscript>He and <Superscript>19</Superscript>C

A theory is developed for describing the diffractive dissociation of loosely bound two-cluster nuclei in the nuclear and Coulomb fields of nuclei having a diffuse boundary. The energy spectra of charged products of the breakup of ²H, ⁶He, and ¹⁹C nuclei are calculated on the basis of the proposed approach, and the results are found to be rather sensitive to nuclear structure. For some angles of neutron and proton emission from the reaction ¹²C(d, np)¹²C, the calculated cross sections are in satisfactory agreement with the results of kinematically complete experiments performed recently to study the breakup of intermediate-energy deuterons.     

Diffraction scattering of Λ 3 H and Λ 6 He hypernuclei on nuclei with allowance for edge diffuseness, the structure of hypernuclei, and multiple-scattering effects

General formulas for the amplitudes of the diffraction scattering of two-and three-cluster loosely bound nuclei on spherical nuclei for an arbitrary dependence of the profile functions on the impact parameter are represented in a form that is convenient for calculations. The differential cross sections for the elastic scattering of _Λ ³ H and _Λ ⁶ He hypernuclei and the total cross sections are obtained with allowance for the diffuseness of the target-nucleus edge, the binding energy of incident hypernuclei, the ranges of nuclear forces between the clusters in the hypernuclei, and multiple (double and triple) scattering. Changes in the behavior of the cross sections in response to a transition from the two-cluster to the three-cluster model of the aforementioned nuclei are revealed.     

New C-C coupling reaction of cyclic nitronates with carbon nucleophiles. Umpolung of the conventional reactivity of nitronates

Cyclic six-membered nitronates 1 are involved in diastereoselective C-C coupling reactions with various nucleophiles in the presence of either catalytic or stoichiometric amounts of TBDMSOTf to give the previously unknown N-siloxytetrahydrooxazines. The intermediacy of N,N-bis(oxy)iminium cations was proven by NMR data.     

Nitration and bromination of benzo-1,2,3,4-tetrazine 1,3-dioxides

Benzo-1,2,3,4-tetrazine 1,3-dioxide (BTDO) and its derivatives were nitrated with HNO₃/H₂SO₄ or HNO₃/oleum and brominated with dibromoisocyanuric acid in CF₃CO₂H/H₂SO₄ (5 : 1) or H₂SO₄. The reactivity of positions in the benzene ring of this heterocyclic system as regards electrophilic substitution was found to change in the following order: 5 7 > 8 > 6. Mono- and dinitro-BTDOs and mono- and polybromo-BTDOs were synthesized. Their structures were confirmed by ¹H, ¹³C, and ¹⁴N NMR spectra.     

Dinitramide and its salts

The methods for preparation and the properties of dinitramide salts with ammonia, hydrazine, hydroxylamine, formamidine, their alkylated and aminated derivatives,etc. are described.For Part 5, seeRuss. Chem. Bull., 1994,43, 1680.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 113–117, January, 1995.     

Nucleophilic trifluoromethylation of arylidenemalononitriles

A method for the nucleophilic trifluoromethylation of arylidenemalononitriles using Me₃SiCF₃ is described. The reaction is carried out in dimethylformamide in the presence of AcONa as a Lewis base, and affords products of Michael addition in high yield.