A Regioselective Synthesis of Novel Functionalized Organochalcogen Compounds by Chalcogenocyclofunctionalization Reactions Based on Chalcogen Halides and Natural Products

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO₃ affording bis[(7-isopropyl-4-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] and bis[(4-isopropyl-7-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] selenides in 90–92% yield. Similar sulfides were obtained in 70–72% yields by the reaction of sulfur dichloride in chloroform under reflux. Trihalotellanes containing the same organic moieties were synthesized from allyl thymol, allyl carvacrol and tellurium tetrachloride or tetrabromide in quantitative yields. Corresponding functionalized ditellurides were prepared in 91–92% yields by the reduction of the trichlorotellanes with sodium metabisulfite in two-phase solvent system. The comparison of reactivity of sulfur, selenium and tellurium halides in chalcogenocyclofunctionalization and distinguishing features of each reaction were discussed.     

Synthesis of functionalized heterocycles by alkylation of β-dicarbonyl compounds with 2,3-dibromopropan-1-ol

Alkylation of β-dicarbonyl compounds with 2,3-dibromopropan-1-ol in the K₂CO₃-dibenzo-18-crown-6 system in toluene leads to products of C,O- or C,C-cycloalkylation. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1695–1697, September, 1997.     

Reactions of 2,3-dichloro-1-propene with sulfur and tellurium in the system hydrazine hydrate-KOH

2,3-Dichloro-1-propene reacts with sulfur dissolved in the system hydrazine hydrate-KOH (with formation of K₂S₂ or K₂S) to afford bis(2-chloro-1-propene-3-yl)sulfide as the main product in both cases. Under similar conditions tellurium induces β-elimination of both chlorine atoms resulting in the formation of allene and complete regeneration of tellurium metal.     

Stable carbenes. Synthesis and properties of benzimidazol-2-ylidenes

A new stable crystalline carbene, 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, was synthesized by decomposition of 1,3-bis(1-adamantyl)-2,3-dihydro-1H-benzimidazol-2-ylacetonitrile on heating under reduced pressure. Heteroaromatic 1,3-R₂-disubstituted benzimidazol-2-ylidenes, both stable (R = 1-Ad) and generated in situ (R = Me, Bzl), as well as 1,3,4,5-tetraphenylimidazol-2-ylidene (generated in situ), reacted with acetonitrile to give the corresponding insertion products, 1,3-disubstituted 2-cyanomethyl-2,3-dihidro-1H-(benz)-imidazoles. The geometric parameters of 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, determined by X-ray analysis, suggest its lower aromaticity as compared to imidazol-2-ylidenes and 1,2,4-triazol-5-ylidenes. The structures of 2-cyanomethyl-2,3-dihydro-1H-benzimidazoles, 2-cyanomethyl-1,3,4,5-tetraphenyl-2,3-dihydro-1H-imidazole, and 1-(1-adamantyl)-5-cyanomethyl-3,4-diphenyl-4,5-dihydro-1H-1,2,4-triazole are characterized by partial conjugation in the heteroring; some compounds exhibit luminescence under UV irradiation. 1,3-Bis(1-adamantyl)benzimidazol-2-ylidene reacted with molecular sulfur in benzene to give 1,3-bis-(1-adamantyl)-2,3-dihydro-1H-benzimidazole-2-thione, but it failed to react with selenium under analogous conditions.     

Regioselective reactions of sulfur, selenium and tellurium chlorides with allyl trimethyl silane

Electrophilic addition of SCl₂, SeCl₂ and SeCl₄ to 2 equivalents of allyl trimethyl silane proceeds regioselectively to give bis[2-chloro-3-(trimethylsilyl)propyl] sulfide, selenide and selenium dichloride, respectively. The reaction with TeCl₄ affords only diallyl tellurium dichloride. The structures of the compounds were confirmed by ¹H, ¹³C, ⁷⁷Se and ¹²⁵Te NMR techniques.     

Selective synthesis of isomeric dithioglycerols

Reactions of 2,3-dibromopropan-1-ol and 1,3-dichloropropan-2-ol with elemental sulfur activated in the system hydrazine hydrate-2-aminoethanol at 30–35°C gave oligomeric polysulfides which were subjected to reductive cleavage with formation of individual dithioglycerol isomers. Activation of sulfur with the use of alkali gives rise to mixtures of isomeric products.     

25,26-Dialkoxycalix[4]arenes. Part 1: 25-Alkoxy-26,27-diacetoxy route

Acetylation of calix[4]arene 1,3-dialkyl ethers yielded the corresponding monoacetates. The ¹H NMR spectral analysis indicated that the products’ alkoxy moieties were ‘rotation restricted’. Acylation of calix[4]arene monoalkyl ethers with acetyl chloride yielded monoacetates and/or 2,3-diacetates in different reaction conditions. A simple recrystallization process was able to isolate 2,3-diacetates in good yield. The ¹H NMR spectra of the diacetylated products indicated that those compounds also possessed the ‘rotation restricted’ alkoxy moieties. In the presence of K₂CO₃ as reaction base, alkylation of 2,3-diacetates produced the acetyl-migrated 1,3-dialkyloxy derivatives. Basic hydrolysis of the acetyl-migrated compounds yielded the known 1,3-dialkoxycalix[4]arenes. In the presence of NaH as reaction base, 2,3-diacetates were alkylated with and without the acetyl-migration. For the highly reactive benzyl bromide and allyl bromide, the majority of alkylation proceeded without acetyl-migration. In the other alkyl halides, the products were the acetyl-migrated 1,3-dialkoxy derivatives along with less than one-fourth the amount of non-migrated 1,2-dialkoxy derivatives.     

Azines and azoles: CXXIII. Three-component condensation of 5-acetyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-dione with o-phenylenediamine and carbonyl compounds as a convenient synthesis of substituted 1,5-benzodiazepines

Readily accessible 5-acetyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-dione reacted with an equimolar amount of o-phenylenediamine under mild conditions (propan-2-ol, 5 min, reflux) to give the corresponding Schiff base. Reactions of the latter with aldehydes and ketones in propan-1-ol in the presence of a catalytic amount of trifluoroacetic acid or in acetic acid led to the formation of 4-hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones.     

四氟乙烯齐聚体的反应: II.四氟乙烯五聚体和烯丙醇的反应及反应产物的转化

The reaction of perfluoro- (3, 4-dimethyl-3-ethylhexene-(2)) (1) with allyl alcohol under different conditions gave different products. Compound 1 reacted with sodium allyl alcoholate yielding 2-(1'-allyloxy-tetrafluoroethyl)-perfluoro(3-methyl-3-ethylpentene- (1))(2). In the presence of triethylamine, 1 reacted with allyl alcohol to give 2-allyloxy-perfluoro (3, 4-dimethy1-4-ethylhexene- (2))(3), and in the presence of acetone and K2CO3 to give compound 4. These reactions all gave allyl-3-trifluoromethyl-3- pentafluoroethyl-2,2-dihydro-pentafluorovalerate (5a) as byproduct. Compound 1 reacted with allyl alcohol in the presence of triethylamine at 20-22`C to give 2, at 30-35`C to give a mixture of 2 and 3 and at 35-40`C to give a mixture of 3 and 5a respectively. Compound 2 was transformed to compound 4 in acetone and in the psesence of K2CO3, \o\ compound 5a or 5b in the corresponding alcohol and to compound 6 on reacting with dimethylamine. Compound 2 as well as 3 was converted to perfluoro-(3-ethyl-2,3,4,5- tetramethyl-2,3-dihydrofuran) (7) by KF in sulpholane.     

Inverse electron demand asymmetric cycloadditions of cyclic carbonyl ylides catalyzed by chiral Lewis acids—Scope and limitations of diazo and olefinic substrates

High enantioselectivities (94-96% ee) were obtained for the inverse electron-demand 1,3-dipolar cycloadditions between cyclohexyl vinyl ether and 2-benzopyrylium-4-olate generated via Rh₂(OAc)₄-catalyzed decomposition of o-methoxycarbonyl-α-diazoacetophenone. The reactions were effectively catalyzed by Eu(OTf)₃, Ho(OTf)₃, or Gd(OTf)₃ complexes (10 mol %) of chiral 2,6-bis[(4S,5S)-4,5-diphenyl-2-oxazolinyl]pyridine. The reactions with the other electron-rich dipolarophiles such as allyl alcohol, 2,3-dihydrofuran, and butyl-tert-butyldimethylsilylketene acetal showed moderate enanantioselectivities (60-73% ee). Good to high enantioselectivities (73-97% ee) were also obtained for the cycloadditions between 3-acyl-2-benzopyrylium-4-olates, generated from methyl 2-(2-diazo-1,3-dioxoalkyl)benzoates and butyl or cyclohexyl vinyl ethers, in the presence of binaphthyldiimine (BINIM)-Ni(II) complexes (10 mol %). Under similar conditions, the reaction between methyl 2-(2-diazo-1,3-dioxohexyl)benzoate and 2,3-dihydrofuran was highly endo-selective, and moderately enantioselective (70% ee). For the BINIM-Ni(II)-catalyzed reactions of cyclohexyl vinyl ether, the use of an epoxyindanone as the 3-acyl-2-benzopyrylium-4-olate precursor revealed that the chiral Lewis acid can function as a catalyst for asymmetric induction. The scope of the cyclic carbonyl ylides was extended to those generated from 1-diazo-2,5-pentanedione derivatives, which were reacted with butyl or TBS vinyl ether and catalyzed using the (4S,5S)-Pybox-4,5-Ph₂-Lu(OTf)₃ complex to give good levels of asymmetric inductions (75-84% ee).     

Reactions of 2,3-Dichloro- and 2,3,5-Trichloro-4,4-ethylenedioxy-2-cyclopentenones with Some O-, S-, and N-Nucleophiles

2,3-Dichloro- and 2,3,5-trichloro-4,4-ethylenedioxy-2-cyclopentenones react with allyl and benzyl alcoholates and thiolates and benzylamine to give products resulting from Ad_NE substitution of the 3-chlorine atom, [1,3]-sigmatropic rearrangement, and cleavage of the C¹-C² bond.     

Reactions of bromine-containing organozinc compounds derived from α,α-dibromo ketones with 2-arylmethylideneindan-1,3-diones and 5-arylmethylidene-2,2-dimethyl-1,3-dioxane-4,6-diones

Bromine-containing organozinc compounds generated from 1,1-dibromo-3,3-dimethylbutan-2-one reacted with 2-arylmethylideneindan-1,3-diones and 5-arylmethylidene-2,2-dimethyl-1,3-dioxane-4,6-diones to give 3-aryl-2-(2,2-dimethylpropanoyl)spiro[cyclopropane-1,2′-indan]-1′,3′-diones and 1-aryl-6,6-dimethyl-2-(2,2-dimethylpropanoyl)-5,7-dioxaspiro[2.5]octan-4,8-diones, respectively. Reactions of 2-arylmethylideneindan-1,3-diones with bromine-containing zinc enolates derived from 1-aryl-2,2-dibromopropan-1-ones and 2,2-dibromo-1,2,3,4-tetrahydronaphthalen-1-one resulted in the formation of 2-aroyl-3-aryl-2-methylspiro-[cyclopropane-1,2′-indan]-1′,3′-diones and 2,3: 8,9-dibenzo-12-phenyldispiro[4.0.5.1]dodecane-1,4,7-trione, respectively.     

A total synthesis of methylenomycin B

A new synthesis of methylenomycin B (1) has been accomplished in four steps starting with a NI(CO)₄ promoted cyclocondensation reaction of allyl chloride and 2-butyn-1-ol in MeOH, followed by hydrogenolysis of the resulting mixture to 2,3-dimethyl-5-methyl-oxycarbonylmethyl-2-cyclopentenone (3), which by hydrolysis and oxidative decarboxylation yielded 1.     

Polytellurides and Polyselenides – Compounds Containing $_{\infty}^{1}\rm [Te_{6}-Te_{4}]^{4-}$ and [Sn(Se4)3]2− Anions

The reactions of the Zintl phase K₂Cs₂Sn₉ with elemental tellurium and selenium in ethylenediamine have been investigated. From the reaction of K₂Cs₂Sn₉ with elemental tellurium [K‐(2,2,2‐crypt)]₄Te₆Te₄ ( 2 ) and [K‐(2,2,2‐crypt)]₂Sn₂Te₃ ( 3 ) were obtained, whereas the reaction of K₂Cs₂Sn₉ with elemental selenium led to the formation of [K‐(2,2,2‐crypt)]₂Sn(Se₄)₃ ( 4 ) and [K‐(2,2,2‐crypt)]₂Cs₂Sn₂Se₆·2en ( 5 )¹⁾. Compounds 2 , 4 , 5 have been characterized by single crystal X‐ray structure determination.     

新型多取代硫代半卡巴腙类配体的合成与结构表征

为发展金属离子配体,设计合成了一系列新型多取代氨基硫脲。烯丙基异硫氰酸酯与水合肼溶液反应,制得4-烯丙基氨基硫脲(1)。1分别与联乙酰(2,3-丁二酮)、水合茚三酮、乙二醛反应,合成出联乙酰双缩(4-烯丙基氨基硫脲)(2)、茚三酮-1,3-二缩(4-烯丙基氨基硫脲)(5)、乙二醛二缩(4-烯丙基氨基硫脲)(6)。联乙酰和氨基硫脲反应制备出联乙酰双缩氨基硫脲(3),环己酮与1在无水乙醇中回流反应合成出环己酮缩(4-烯丙基氨基硫脲)(4)。缩合反应操作简便,条件温和,反应时间只需0.5～2h,产物收率达到70%～87%。这些化合物均未见报道,其结构通过元素分析,IR、^1HNMR和MS进行鉴定。初步测试了它们对金属离子的配位性能,这些多取代氨基硫脲配体很容易与Cu^2^+、Co^2^+、Ni^2^+、Zn^2^+、Ag^+、Hg^2^+、Hg^2^+~2及稀土离子形成稳定的螯合物。     

Synthesis and characterizations of some new selenolo[2,3-b]quinoxaline derivatives

In this paper, we present the synthesis of new selenoloquinoxaline derivatives starting from 2-chloroquinoxaline-3-carbonitrile 1 . The compound 1 was subjected to a reaction with selenium metal in the presence of NaBH₄ as a reducing agent in ethanol, under a nitrogen atmosphere. This reaction resulted in the formation of the sodium salt of 3-cyanoquinoxaline-2-selenolate, which was subsequently reacted with α-halogenated carbonyl compounds in situ. This reaction produced a series of newly synthesized 3-aminoselenolo[2,3-b]quinoxaline-2-substituents. Ethyl 3-aminoselenolo[2,3-b]quinoxaline-2-carboxylate 3a was hydrolyzed by sodium hydroxide to give the corresponding sodium salt 9 . This salt was then refluxed with acetic anhydride to produce oxazinone compound 10 . The reaction of compound 10 with ammonium acetate afforded pyrimidoselenolo[2,3-b]quinoxaline derivative 11 . Compound 11 was then chlorinated using phosphorous oxychloride to give the corresponding chlorocompound.     

Interaction of 2,2,6,6-tetramethylpiperidine-1-oxyl chloritewith alcohols

The kinetics of the oxidation of a series of alcohols (viz., ethanol, propan-2-ol, butan-1-ol, butan-2-ol, heptan-4-ol, decan-2-ol, propan-1,3-diol, butan-2,3-diol, cyclohexanol, benzyl alcohol, and borneol) with the oxoammonium salt 2,2,6,6-tetramethylpiperidine-1-oxyl chlorite in acetonitrile was studied by spectrophotometry. The products of oxidation of primary alcohols are the corresponding aldehydes and carboxylic acids, and the products of oxidation of secondary alcohols are ketones. The reaction rate is described by the second order equation. The rate constants and activation parameters were determined. The rate constant as a function of the alcohol nature is described by the one-parameter Taft equation.     

丙烯醇反马氏水合制备1,3-丙二醇

1,3-丙二醇具有很高的经济价值，是合成纤维聚对苯二甲酸丙二酯的重要原料。基于甘油甲酸介入法获得的丙烯醇作为平台分子，通过丙烯醇与TiCl4-NaBH4反应，首次实现常温常压下1,3-丙二醇的制备, 为1,3-丙二醇的合成提供了一条新的路径。在最优条件下，1,3-丙二醇的产率68.73%，推测反应机理为：TiCl4和NaBH4发生反应，生成中间体 “BH3”，进而实现了丙烯醇反马氏水合制备1,3-丙二醇。     

A PhSeCl-mediated allylic oxidation of prenyl moiety: a convenient method for the construction of 3-isopenten-2-ol unit

A phenylselenenyl chloride (PhSeCl)-mediated allylic oxidation to give allylically rearranged alcohol has been developed. A possible mechanism for the present reaction is generation of allylic selenide from prenyl moiety via [1,3]-sigmatropic rearrangement, followed by oxidation and [2,3]-sigmatropic rearrangement to afford 3-isopenten-2-ol.     

Isomerization of perfluoro-3,3-diethylindan-1-one into perfluoro-1,3-dimethyl-4-ethyl-1 H-isochromen under the action of antimony pentafluoride

The heating of perfluoro-3,3-diethylindan-1-one with SbF₅ at 180°C after treatment of the reaction mixture with anhydrous HF afforded perfluoro-1,3-dimethyl-4-ethylisochromen, and after hydrolysis, perfluoro-1,3-dimethyl-4-ethyl-1H-isochromen-1-ol. The latter under the action of NaHCO₃ converted into 5,6,7,8-tetrafluoro-1,3-bis(trifluoromethyl)-1H-isochromen-1-ol. Both isochromenols reacted with SOCl₂ gave the corresponding polyfluoro-1-chloro-1H-isochromens. On dissolving isochromenols in CF₃SO₃H and isochromens in SbF₅ perfluoro-1,3-dimethyl-4-ethylisochromenyl and 5,6,7,8-tetrafluoro-1,3-bis(trifluoromethyl)isochromenyl cations were generated which by hydrolysis were converted into the corresponding isochromenols.