The chemistry ofN,N-bis (trialkylsilyloxy) enamines

The reactions of primary amines withN,N-bis(trimethylsilyloxy) enamines can give products of both mono-and bis-α-oximinoalkylation of primary amines. The steric restrictions in both reactants substantially retard bis-α-oximinoalkylation. A general method for the synthesis of α-amino-substituted oximes from primary amines and bis-silyl derivatives of aliphatic nitro compounds was developed. For Part 1, see Ref. 1. Published inIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1265–1272, July, 2000.     

Chemistry of N,N-bis(silyloxy)enamines. 4. Study of the reactions of N,N-bis(silyloxy)enamines with 1,3-diones

Smooth C,C-cross-coupling of N,N-bis(silyloxy)enamines with methyl malonates gives the corresponding methyl -hydroxyiminoalkylmalonates.     

Chemistry of <Emphasis Type="Italic">N,N</Emphasis>-bis(silyloxy)enamines 7. Quaternization of tertiary amines and nitrogen-containing heterocycles by <Emphasis Type="Italic">N,N</Emphasis>-bis(silyloxy)enamines

Coupling of N,N-bis(silyloxy)enamines with tertiary amines and nitrogen-containing heterocycles affording the corresponding functionalized ammonium or iminium salts was studied. The area of its application was determined, and optimal procedures for the synthesis of the target products were proposed. The mechanism including the formation of conjugated nitroso alkene or a silylnitrosonium cation as key intermediates is discussed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2137–2143, October, 2004.     

Reaction ofN,N-bis(chloromethyl)amides withN,N′-diacylated alkene(arylene)diamines

Reactions ofN,N-bis(chloromethyl)amides withN,N′-diacyl derivatives of ethylenediamine (oro-phenylenediamine) result in formation of the corresponding 1,3,5-triacylated perhydro-1,3,5-triazepines (or their benzoanalogs) or 1,3-diacylated imidazolidines (or their benzoanalogs). Reactions ofN,N-bis(chloromethyl)amides withN,N′-ditosylated trimethylenediamine occur in a similar way. The direction of the reactions depends on the type of the acyl substituents and the strength of the bases. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2270–2273, November, 1998.     

Novel synthesis of α-nitroalkenes from nitroalkanes via halogenation of intermediate N,N-bis(silyloxy)enamines

An approach to conjugated nitroalkenes via oxidation of N,N-bis(silyloxy)enamines with bromine or iodine in the presence of tetra-n-butylammonium acetate is described. The acetate ion plays a key role by acting as a mild desilylating reagent. This new strategy allows the synthesis of α-nitroalkenes from the corresponding nitroalkanes.     

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 and chemical transformations of silicon-containing derivatives ofN,N-dimethylhydrazine

Reactions of carbofunctional organosilicon compounds withN,N-dimethyl-N′-trimethylsilylhydrazine andN,N-dimethyl-N′,N′-bis(trimethylsilyl)hydrazine were studied. The composition and structure of the reaction products were found to be dependent on the reagent nature and the reaction conditions. 1,4-Dimethylamino-2,2,5,5-tetramethyl-1,4-diaza-2,5-disilacyclohexane, a first representative of a new type of 2,5-disilapiperazines, was synthesized. A scheme of its formation was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 169–173, January, 1999.     

Photoinduced electron transfer in N,N-bis(pyridylmethyl)naphthalenediimides: study of their potential as pH chemosensors

The change in fluorescent properties of a series of N,N-bis(pyridylmethyl)naphthalenediimides (BIPy-NDIs) as function of pH were investigated. The naphthalenediimide dyes displayed OFF–ON pH sensing properties owing to photoinduced electron transfer in the pH range from 1.7 to 4.1. The fluorescence enhancement of the chemosensors studied is based on the hindering of photoinduced energy-electron transfer (PET) from pyridine ring to the naphthalene fluorophore by protonation. Moreover, using density functional theory theoretical calculations of molecular orbitals, it was verified that protonation nitrogen atom in pyridine ring inhibits the PET process. The best selective response for monitoring pH in the presence of different metal ions, was exhibited by BIPy-NDI 1B. In addition, 1B was applied for determination of pH in real samples of commercial vinegars. The results were consistent with those obtained by glass electrode method, indicating that the new probe could be a practical pH indicator in strongly acidic conditions.     

Reactions of 1,3,3,3-tetrafluoro-2-methoxycarbonylpropenesulfenyl chloride with enamines

1,3,3,3-Tetrafluoro-2-methoxycarbonylpropenesulfenyl chloride readily reacts with enamines (derivatives of -oxo acids) to give sulfenylation products. The reactions with N-aryl-substituted enamines are accompanied by cyclization to form N-aryl-2-(2,2,2-trifluoro-1-methoxycarbonylethylidene)-2,3-dihydrothiazoles.     

N-Polyfluoro(trimethylsilyl)ethyl azole derivatives

A facile synthetic route to N-polyfluoro(trimethylsilyl)ethyl azole derivatives was developed starting from N-bromo(chloro)polyfluoroethyl-substituted azoles. The silanes thus obtained were reacted with various electrophiles in the presence of the fluoride ion to yield the corresponding fluorinated carbinols, ketones, carboxylic acids, and methyl dithiocarboxylates as well as N-pentafluoroethylbenzimidazole.     

Reactions of hexaorganyldigermoxanes with O-trimethylsilyl carbamates

Hexa-n-butyl- and hexaisopentyldigermoxanes but not hexaphenyldigermoxane react with O-trimethylsilyl N,N-diethylcarbamate and trimethylsilyl piperidinocarboxylate to give O-triorganylgermyl carbamates.     

O-Halogensilyl-N,N-bis(trimethylsilyl)hydroxylamine – Synthese,Kristallstruktur und Reaktionen

O-Halogenosilyl-N,N-bis(trimethylsilyl)hydroxylamines – Synthesis, Crystal Structure, and Reactions The substitution of halogenosilanes on lithiated N,O-bis(trimethylsilyl)-hydroxylamine in the molar ratio of 1 : 1 occurs on the oxygen atom. The O-halogenosilyl-N,N-bis(trimethylsilyl)hydroxylamines were prepared: RSiF₂ON · (SiMe₃)₂ (R = CMe₃ 1 , CHMe₂ 2 , CH₂C₆H₅ 3 , C₆H₂(CMe₃)₃ 4 ), RR′SiFON(SiMe₃)₂ (R = CMe₃, R′ = C₆H₅ 5 ; R = Me, R′ = C₆H₅ 6 ; R = C₆H₂Me₃, R′ = C₆H₂Me₃ 7 ; R = CH₂C₆H₅, R′ = CH₂C₆H₅ 8 ; R = CHMe₂, R′ = CHMe₂ 9 ; R = CMe₃, R′ = CMe₃ 10 ), RSiCl₂ON(SiMe₃)₂ (R = CMe₃ 11 ; R = Cl 12 ). The reaction of fluorosilanes with lithiated N,O-bis(trimethylsilyl)hydroxylamine in the molar ratio of 1 : 2 leads to the formation of O,O′-fluorosilyl-bis[N,N-bis(trimethylsilyl)hydroxylamines]: RSiF[ON(SiMe₃)₂]₂ (R = CMe₃ 13 ; R = C₆H₅ 14 ). 13 could be prepared in the reaction of 1 with LiON(SiMe₃)₂. Lithiated dimethylketonoxime reacts with 1 to Me₂C=NOSiRF–ON(SiMe₃)₂ [R = CMe₃ ( 15 )]. The first crystal structure of a tris(silyl)hydroxylamine ( 4 ) is shown. The angle at the nitrogen prove a pyramidal geometry.     

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.     

Chemical properties ofN-(amidomethy)- andN-(imidomethyl)glycine derivatives 2. Reactions at alkoxycarbonyl and carboxyl groups

N-(Aroylarnmomethylfglycine amides were synthesized by reactions ofN-(aroyllminomethyl) glycine esters with ammonia. Alkaline hydrolysis ofN-(amidomethyl)glycine,N-(irnidornethyl)glycine, andN-(amidomethyl)pheriylalariiiie esters afforded the correspondingN-(amidowthyVa-amirio acids- Reactions of the Last-mentioned compounds with ethyl esters of glycine, alanine, and phenylalanine in the presence of dicyclohexylcarbodiimide yielded dipeptides containingNh-amidomethyl substituents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1770–1771, July, 1996.     

Vibrational spectra and structure ofN,N-dinitromethylamine

The vibrational (IR and Raman) spectra ofN,N-dinitromethylamine were studied. The assignments of the bands were carried out using a comparison of spectra obtained in different aggregate states, invoking the results of normal coordinate analysis. The most probable symmetry of the molecule was shown to beC _s with a planar configuration of the N(NO₂)₂ moiety.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1503–1507, August, 1995.     

N-methyI-N-(triethoxysilylmethyl) andN-methyl-N-(silatran-1-ylmethyl) substituted glycine and alanine

Organosilicon derivatives of glycine, - and -alanine, and -methylalanine were prepared by the reaction of methyl esters of - and -halocarboxylic acids withN-methylaminomethyltriethoxysilane in the presence of triethylamine. The compounds synthesized were converted into the correspondingN-silatran-l-ylmethyl derivatives. Trimethylsilyliodoacetate reacts withN-methylaminomethyltrietoxysilane to give 2,2-diethoxy4-methyl-1-oxa-4-aza-2-silacyclohexane-6-one. Its reaction with triethanolamine leads toN-methyl-N-(silatran-l-ylmethyl)glycine.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 341–343, February, 1995.     

Reactions of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates

2-(Alkoxycarbonylmethylidene)-4-aryl-5-(dialkylamino)thiophen-3(2H)-ones were synthesized by condensation of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates. Intermediate substituted vinylic sulfides were isolated. When heated or in the presence of an acid or a base, they undergo cyclization into thiophenes.     

Syntheses based on (N,N-difluoroamino)dinitroacetonitrile

High reactivity of the nitrite group in (NN-difluoroamino)dinitroacetonitrile was demonstrated. Based on its reaction with HN₃, a new preparative method for the synthesis of 5-[(N,N-difluoroamino)dinitromethylltetrazole was developed; some derivatives of the latter compound have been obtained.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8. pp. 2056–2058, August, 1996.     

Reactions of benzimidazole-2-carbaldehyde with enamines

Benzimidazole-2-carbaldehyde reacts with 1-morpholinocyclohexene, 1-morpholinocyclopentene, and aminocrotonic ester upon heating to form 4a,11-dimorpholino-1,2,3,4,11,11a-hexahydro-4aH-indolo[1,2-a]benzimidazole, 2-(2-morpholino-4,5-dihydrofulvenyl)benzimidazole, and 4-(benzimidazol-2-yl)-3,5-diethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 566–571, March, 1999.