Synthesis and reactivity of 3-(2-chloroalkyl)-2,2-dihaloaziridines

3-(2-Chloroalkyl)-2,2-dihaloaziridines were synthesized via cycloaddition of dihalocarbenes to the CN double bond of β-chloroimines. Under the action of Lewis acids or HCl, N-C³ bond cleavage occurred, giving rise to N-substituted 2,4-dichloro-3,3-dimethylbutanamides, which were further converted to 3-chloropyrrolidin-2-ones under alkaline conditions. When 2,2-dichloro-3-(2-chloro-1,1-dimethylethyl)-1-phenylaziridine was reacted with sodium methoxide, aziridine ring opening with N-C² bond cleavage took place, leading to methyl 4-chloro-3,3-dimethyl-2-(phenylamino)butanoate.     

Synthesis and reactions of 3-alkylsulfanyl-1,3-dihydro-2,1-benzisothiazole 2,2-dioxides

Alkyl- and arylsulfanylation of 1,3-dihydro-2,1-benzisothiazole 2,2-dioxides (benzosultams) 1a-c and pyridosultam 1d with dialkyl and diaryl disulfides provides dithioacetals of 2-aminobenzaldehydes 6-13. 1,3-Dimethylbenzosultam 19 with disulfides forms 3-alkyl(aryl)sulfanyl-1,3-dimethylbenzosultams 20-22 that undergo thermal extrusion of SO₂ followed by a [1,5] sigmatropic hydrogen shift in the intermediate aza-ortho-xylylene leading to 1-arylvinyl sulfides 24-26. Tandem alkylation-sulfanylation of benzo- and pyridosultams 1a-d with 4-bromobutyl thiocyanate gives tetrahydrothiopyrano-spiro-benzosultams 27-30 that, after extrusion of SO₂ and [1,5] hydrogen shift, form 2-aryl-5,6-dihydro-4H-thiopyrans 32-35. Alkylation of pyridosultam 1d with 3-chloropropyl thiocyanate leads directly to 2-pyrido-3,4-dihydrothiophene derivative 37.     

2,3-二芳基-1,3-苯并噁嗪的合成及杀菌活性

在三甲基氯硅烷(TMSCl)的催化作用下,取代苯甲醛与邻(芳胺甲基)苯酚经N杂缩醛化反应生成了一系列2,3-二芳基-1,3-苯并噁嗪类化合物。 目标化合物的结构用IR、¹H NMR、¹³C NMR和元素分析等技术手段进行了表征。 对所合成的化合物进行了初步杀菌活性测试,部分表现出良好的杀菌活性,化合物6e对菌核病菌的抑制活性为79.0%,化合物6a和6d均为74.8%,化合物6e对灰霉病菌的抑制活性为77.9%。     

Tandem coupling reactions of benzynes and 1,3-diones: a novel synthesis of 2,2-diphenyl-1,3-diones

A novel, general, and mild method is described to prepare 2,2-diphenyl-1,3-diones with benzyne using CuBr and trichloroacetic acid as the catalyst.     

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.     

Ipso nitration. Nitrodeformylation reactions in nitrothiophenealdehydes

Nitration of 4-nitro-2-thiophenealdehyde afforded 2,4-dinitrothiophene and small quantities of 4,5-dinitro-2-thiophenealdehyde; 5-nitro-2-thiophenealdehyde gave instead 3,5-dinitro-2-thiophenealdehyde as the main product and some 2,5-dinitrothiophene. The two dinitrothiophenes form through a nitrodeformylation reaction which represents an interesting example of the nitration at an ipso position in a strongly deactivated substrate.     

Cascade Transformations of (2,2-Diaryl-3,3-dichloroaziridin-1-yl)acetates

Esters of (2,2-diaryl-3,3-dichloroaziridin-1-yl)acetic acid prepared from glycine derivatives under alkylation conditions afford esters of 2-[N-alkyl-N-(2,2-diaryl-1-cyanovinyl)amino]-3,3-diarylacrylic acid in 20-40% yield. The reaction resulting in these compounds proceeds through a cascade of 3-chloro-2-azadiene and ylide intermediates. 3-Chloro-2-azadienes originating from (2,2-diaryl-3,3-dichloroaziridin-1-yl)acetates react with primary and secondary amines at the carbon atom of imine group providing ketenimines which undergo ketenimine-nitrile rearrangement or fragmentation. The other bases (KOH, MeONa, DBU) effect dehydrochlorination of the mentioned 3-chloro-2-azadienes giving nitrile-ylides which are trapped by nucleophilic reagents. The 3-chloro-2-azadiene obtained from methyl (2,2-diaryl-3,3-dichloroaziridin-1-yl)acetate and DBU was relatively stable and was isolated as an individual compound. (2,2-diaryl-3,3-dichloroaziridin-1-yl)propionates behave as nonfunctionalized dichloroaziridines.     

A DFT investigation of alkyne bromination reactions

[Structure: see text]. A DFT calculation study of the addition reaction between molecular bromine and the number of symmetrical or unsymmetrical substituted alkynes 1 (R-CC-R'), where R = R' = H (1a), Me (1b), t-Bu (1c), or Ph (1d), or R = H and R' = Me (1e), t-Bu (1f), or Ph (1g), was performed. Two possible reactions were checked: (a) the reactions suitable for the gas-phase interactions, which start from a 1:1 Br2-alkyne pi-complex and do not enter into a 2:1 Br2-alkyne pi-complex; and (b) the processes passing through a 2:1 Br2-alkyne pi-complex, which look more realistic for the reactions in solutions. The structures of the starting reactants and the final products as well as the possible stable intermediates have been optimized. The transition states of the predicted process have been found. Both trans- and cis-dibromoalkenes (2 and 3) may ensue without the formation of ionic intermediates from a pi-complex of two bromine molecules with the alkyne (solution reactions). The geometry around the double bond forming in dibromoalkenes strongly depends on the nature of the substituents at the triple bond. The "cluster model" was also used for the prediction of solvent influence on the value of the activation barrier of the but-2-yne (1b) bromination reaction.     

Acetylation,bromination, and nitration of benzoxaheterocycles and synthesis of β-aminoketones from acetyl derivatives

The method of competing reactions was used to establish the sequence of variation of the relative rates of acetylation, bromination, and nitration reactions of 2-methylcoumaran, chroman, 2,3,4,5-tetrahydrobenzo-1-oxepan, and 1-methoxy-2-ethylbenzene. The isomeric composition of the substitution products formed was determined. The acetyl derivatives were converted according to a Mannich reaction to hydrochlorides of -dimethylaminopropionyl derivatives, possessing antiinflammatory activity.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1035–1038, August, 1984.     

Reaction of 2,4-Diaryl-1,3-dithia-2,4-diphosphetane-2,4-disulfides with resorcinol

Russian Journal of General Chemistry -     

2,2-Diamino-1,3-dimethyl-1,3,2-diazaphospholaniumchlorid

Ohne Zusammenfassung     

4-Functionally Substituted 3-Hetarylpyrazoles: VI. 1,3-Diaryl-4-isocyanatopyrazoles

1,3-Diaryl-4-isocyanatopyrazoles were obtained by reaction of 1,3-diarylpyrazole-4-carboxylic acids with ethyl chloroformate and sodium azide or by reaction of 1,3-diarylpyrazole-4-carbonyl chloride with trimethylsilyl azide. The title compounds react with amines, hydrazine hydrate, alcohols, phenols, and monochloroacetic acid to afford 4-pyrazolyl-substituted ureas, semicarbazides, urethanes, and amides respectively.     

SYNTHESIS OF 2,2-DISUBSTITUTED-1,3-PROPANE-DITHIOLS

Abstract

A method for the preparation of 2,2-disubstituted-1,3-propanedithiols from the corresponding diols is described. The success of the synthesis is governed by the solvent in which the nucleofilic substitution, dimesylate to dirhodanide, is performed. The proposed reaction sequence is tested out for several diols and the overall yields are very good with respect to the strongly hindered[sbnd]sterically ‐neopentyl-structure. All compounds are identified by ¹H-nmr.     

Synthesis of 1,3-diaryl-2,2-dichloroethyleneimines

1,3-Diaryl-2-dichloroethyleneimines were synthesized by the reaction of aromatic Schiff bases with chloroform in the presence of potassium tert-butoxide. Several properties of these compounds were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 180–181, February, 1972.     

Character of the products of bromination of 1,3-dioxacyclanes with N-bromosuccinimide

The dependence of the character and composition of the products of the reaction of equimolar amounts of N-bromosuccinimide and 1,3-dioxacyclanes on the ring size and the character of the substituent in the 2 position of the 1,3-dioxacyclane ring was examined. Reasons for the primary formation of bromination products of different types for five-, six-, and seven-membered cyclic acetals are proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 174–175, February, 1981.     

Oxidation reactions of 1,3-diphenylpropane-1,3-dione

The free radical scavenging properties and possible antioxidant activity of 1,3-diphenylpropane-1,3-dione (1) are reported. Pulse radiolysis technique was employed to study the one-electron oxidation of 1 with various radicals viz. CCl₃O₂ ^•, N₃ ^• and^•OH in homogeneous aqueous solution. All these radicals reacted with 1 under ambient conditions at almost diffusion controlled rates producing transient species with an absorption maximum around 420 nm that decayed at first order rates. The transient absorption peak was shifted in the case of CCl₃OO^• radical reaction with 1 due to change in the polarity of the medium. Formation of a stable product with a broad absorption band starting from 400 nm and cut off at 230 nm was observed in the oxidation of 1 with^•OH and^•N₃ radicals. In a biological system also, 1 showed significant inhibitory activity against Fe²⁺-mediatedlipidperoxidation. Based on these observations, a suitable mechanism for the oxidation of 1 has been proposed.