New Direct Synthesis of 3-Nitro-2H-chromenes Using Nitroethylene

The treatment of substituted 2-hydroxybenzaldehydes by nitroethylene, prealably prepared or generated in situ within the reaction, in the presence of di-n-butylamine gave 3-nitro-2H-chromenes in fair to excellent yields.     

C-甲基硝酮与硝基乙烯1,3-偶极环加成反应及其溶剂效应的理论研究

用密度泛函B3LYP方法研究了硝基乙烯与C-甲基硝酮的1,3-偶极环加成反应, 并利用自洽反应场方法(SCRF)计算了环已烷与乙腈这两种溶剂分别对反应所产生的 影响。该反应进行时反应物的接近有四种方式,对气相情况下和上述两种溶剂中的 反应物、四种可能产物及其相应过渡态和反应前期复合物构型分别进行了优化并计 算了振动频率。四个反应均为放热反应,且均具有很低的反应势垒,四种产物均容 易生成。但在气相反应和以环已烷为溶剂的情况下,生成的产物中endo-4型产物略 占优势;而在乙腈溶剂中得到endo-5型略占优势的产物。     

Efficient synthesis of tertiary amines from secondary amines

Reliable N-alkylations of secondary amines have been developed. By using DIAD and TPP (or PS-TPP) a variety of secondary amines can be converted to the corresponding tertiary amines in good to excellent yields with diverse alkylhalides; no formation of quaternary amine salts are observed. These protocols are amenable to combinatorial chemistry libraries, and are also useful for the syntheses of secondary amines by an acid lysis of the cleavable tertiary amino resins.     

N-Dealkylation of aliphatic amines and selective synthesis of monoalkylated aryl amines

Highly selective alkyl transfer processes of mono-, di- and trialkyl amines in the presence of the Shvo catalyst have been realized; in addition, a general method for N-alkylation of aniline with di- and trialkyl amines is presented.     

New synthesis of trifluorinated amines from 1-bromopropargylic amines in superacid

Treatment of 1-bromopropargylic amines affords the corresponding 1,1,1-trifluoro in one step in HF-SbF₅ medium. 1-Bromo-1,1-difluoro or 2-bromo-1,1,1-trifluoro derivatives could also be prepared, depending on the reaction conditions.     

Electrochemical chlorination of amines

We have studied the laws governing the electrochemical chlorination of primary and secondary amines in aqueous solution on a ruthenium-titanium anode under conditions of diaphragm electrolysis. It was found that in order to ensure the most complete conversion of the amines into the corresponding chloramines it is necessary to add NaHCO₃ to the electrolyte [amine:NaHCO₃=1(1.5–3)]. Under the conditions of electrolysis primary amines are converted almost quantitatively into dichloramines. High yields of the N-chloro-derivatives of secondary amines can be obtained with high current densities and concentrations of NaCl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 620–625, March, 1990.     

Polymers of tertiary amines

Polymers of tertiary amines and their hydrochlorides of molecular weights in the range 300–2000 have been prepared, starting from trans-1,4-dichlorobutene-2, and primary amines. The polymers present interesting solubility properties. Variation of the reaction conditions leads to crosslinked insoluble polymers. Reaction of the soluble tertiary amine polymers with organic acid dichlorides leads to polymers of tertiary amine–amides, a new type of polymer.     

Thiomethylation of heteroaromatic amines

Thiomethylation of heteroaromatic amines with formaldehyde-hydrogen sulfide gave linear and cyclic heteroatom compounds: N,N′-[methylenebis(sulfanediylmethylene)]bishetarenamines and 5-hetaryl-1,3,5-dithiazinanes. N,N′-[Methylenebis(sulfanediylmethylene)]bishetarenamines were found to undergo transformation into 5-hetaryl-1,3,5-dithiazinanes by the action of CH₂O-H₂S. Transamination of 5-methyl-1Hpyrazol-3-amine, 6-nitro-1,3-benzothiazol-2-amine, and 5-bromopyridin-2-amine with 5-methyl-1,3,5-dithiazinane selectively afforded the corresponding 5-hetaryl-1,3,5-dithiazinanes.     

N-anions of heteroaromatic amines

It is shown in four examples that the sodium salts of N-heteroaromatic amines exist in the amino form in the crystalline state.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 363–373, March, 1973.     

N-Anions of heteroaromatic amines

The alkylation of the N-anions of 2- and 4-aminopyridines, 1-aminoisoquinoline, and 2-amino-1-ethylbenzimidazole with C₂-C₄ alkyl halides in liquid ammonia leads to the formation of a mixture of the products of mono- and dialkylation at the NH₂ group (usually with a predominance of the latter). The role of stepwise processes and the yield of the dialkyl derivative increase on passing from alkyl bromides to iodides and from the heavier and branched radicals (C₄H₉, i-C₃H₇) to lighter radicals (C₂H₅).For communication V, see [1].Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 967–971, July, 1973.     

N-anions of heteroaromatic amines

The corresponding 2,2-azobenzimidazoles are formed by the oxidation of N-anions of 2-aminobenzimidazoLe and 1-methyl-2-aminobenzimidazole in liquid ammonia by means of potassium permanganate and potassium persulfate, as well as by oxidation with iodine in ether and autooxidation. In the case of the dianion of 1-methyl-2-aminobenzimidazole, it was demonstrated that the reaction proceeds through a step involving the formation of a hydrazo derivative. Quantitative yields of the previously unknown 2,2-hydrazobenzimidazoles were obtained by reduction of 1,1-dimethyl- and 1,1-diphenyl-2,2-azobenzimidazoles with phenylhydrazine.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 238–241, February, 1972.     

NIS-promoted guanylation of amines

An efficient NIS-promoted guanylation reaction is described. This procedure allows the guanylation of primary and secondary amines through the reaction with di-Boc-thiourea and di-Boc-S-methylisothiourea, respectively. We demonstrated that the use of NIS compares favorably with existing methods and is an attractive alternative to heavy metal or Mukayama’s reagent activation.