A new and general synthesis of chiral β-ketosulfoxides by reaction of (+)-(R)-methyl p-tolyl sulfoxide with nitriles

The nitrile functional group is efficiently transformed into the β-ketosulfoxide moiety by reaction with the anion formed from (+)-(R)-methyl p-tolyl sulfoxide and aqueous acidic work-up of the reaction.     

Halofluorination of 1,2-difluoro-1,2-di(p-tolyl)ethene, 1,2,3,4-tetrafluoro-1,4-di(p-tolyl) butadiene and its nonfluorinated parent compounds

The reactions of (E)-1,2-difluoro-1,2-di (p-tolyl) ethene (1) with N-bromo- or N-chlorosuccinimide gave mainly the expected halofluorination products 1-bromo-1,2-di(p-tolyl)-1,2,2-trifluoroethane (2) or 1-chloro-1,2-di(p-tolyl)-1,2,2-trifluoroethane (4), respectively. As a side reaction halogenation of the double bond has been obtained. With (E,E)-1,4-di(p-tolyl)-1,2,3,4-tetrafluorobuta-1,3-diene (6) under the same conditions the products of 1,2- and 1,4-addition or its consecutive hydrolysis products were isolated. (E)-Stilbene (19) on bromofluorination gave solely erythro-1-bromo-2-fluoro-1,2-diphenylethane (20), while with 1,4-diphenylbuta-1,3-diene (17) mainly higher molecular weight products were formed.     

Rapid high-performance liquid chromatographic method for the determination of peroxyacetic acid

The selective oxidation of methyl p-tolyl sulfide (MTS) to the corresponding sulfoxide (MTSO) by peroxyacetic acid and the subsequent rapid separation of the sulfide and sulfoxide are the basis for a fast and reliable HPLC method for the determination of this oxidizing agent in the presence of hydrogen peroxide. The time required for chromatographic separation was reduced to less than 1 min. To improve the long-term stability of the sulfoxide solution, hydrogen peroxide was decomposed catalytically by manganese dioxide. Even in the presence of a tenfold molar excess of hydrogen peroxide, a storability of at least 20 h without a significant increase in MTSO concentration was achieved. External calibration can be performed using the stable and commercially available MTSO. Real samples from a brewery cleaning-in-place disinfection process were analysed and the results were compared with those of the classical two-step titration.     

Alkylation of p-cresol with tert-butanol catalyzed by heteropoly acid supported on zirconia catalyst

Butylation of p-cresol by tert-butanol was catalyzed by 12-tungstophosphoric acid supported on zirconia (TPA/ZrO₂) under flow conditions. Catalysts prepared with different TPA loading (5–30 wt.%) were calcined at 1023 K and acidity was estimated by temperature programmed desorption (TPD) of NH₃. Fifteen percent TPA/ZrO₂ showed the highest acidity and found to be the most active catalyst in butylation of p-cresol. The effects of temperature, space velocity (LHSV) and molar ratio of the reactants on the conversion of p-cresol and products selectivities were optimized and the optimum reaction conditions evaluated were 403 K, tert-butanol/p-cresol (Bu/Cr) molar ratio 3 and LHSV 4 h⁻¹. Under the optimized conditions, conversion of p-cresol was found to be 61 mol% with product selectivity for 2-tert-butyl-p-cresol (TBC) 81.4%, 2,6-di-tert-butyl-p-cresol (DTBC) 18.1% and tert-butyl-p-tolyl ether (ether) 0.5%. Study of time on stream (TOS) performed as a function of time for 100 h showed that the loss in activity in terms of conversion of p-cresol was 6%.     

Heteroallen-komplexe des molybdänocens

Reactions of the extremely labile molybdenocene olefin complexe Mo(η⁵-C₅H₅)₂[(Z)-C₆H₅CH=CHC₆H₅] with heteroallenes X=C=Y (X=C=Y = CS₂, (p-tolyl)NCN(p-tolyl), (C₆H₅)₂CCO) gives the corresponding heteroallene complexes of molybdenocene Mo(η⁵-C₅H₅)₂(X=C=Y) in high yields. Spectroscopic data clearly indicate a dihapto-coordination of the heteroallenes via the C=X bond (X = O, S, N).     

Thermal, spectral and magnetic studies of some first row transition metal complexes of 2-(p-tolyl) pyridine

Some chloro complexes of cobalt, nickel and copper with 2-(p-tolyl) pyridine have been prepared. The stereochemical configurations of the complexes were deduced using spectral and magnetic properties. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis.     

Thermal fragmentation and rearrangement of N-arylbenzamidoxime and O-phenylsulfonyloxime derivatives

Thermal fragmentation of N-arylbenzamide oximes I, II (Ar = Ph, p-tolyl) under nitrogen gives rise to benzanilide and 2-phenylbenzoxazole as the major products, in addition to benzonitrile, arylamines, phenols, benzoic acid, o- and p-aminophenols and benzimidazole derivatives. In the presence of naphthalene as radical scavenger, I gave - and β-naphthols beside the previous products. Also, heating N-arylbenzamide O-phenylsulfonyloximes III under reflux in boiling tetralin lead to the formation of benzonitrile, arylamines, diphenylamine, benzenesulfonic acid, diphenyl sulfone, 1-hydroxytetralin, -tetralone, and 1,1′-bitetralyl as the major products. Analogous results are obtained on heating III in the presence of isoquinoline as a radical trap which formed 1-phenylisoquinoline. The isolated products have been interpreted in terms of a free radical mechanism involving the homolysis of NO and/or CN bonds.     

An asymmetric synthesis of carboxylic acid derivatives,including lactic acid and α-amino acid derivatives,from optically active 1-chlorovinyl p-tolyl sulfoxides and ester lithium enolates with creation of chirality at the α-position

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones or methyl formate and (R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent (alkyl, alkoxy, or dibenzylamino group) at the α-position with high 1,4-chiral induction from the sulfur chiral center. The adducts were converted to optically active esters, lactic acid, and α-amino acid derivatives having a chiral center at the α-position. When this addition reaction was carried out with an ester enolate generated from excess carboxylic acid tert-butyl ester with LDA in the presence of HMPA, the diastereomer of the adduct was obtained. By using the two reaction conditions for the generation of the ester enolate, a new method for asymmetric synthesis of both enantiomers of carboxylic acid derivatives having a substituent at the α-position from the one chiral source, (R)-(−)-chloromethyl p-tolyl sulfoxide, was achieved.     

A novel method for asymmetric synthesis of both enantiomers of α-substituted carboxylic acid derivatives from optically active 1-chlorovinyl p-tolyl sulfoxides and lithium ester enolates with 1,4-chiral induction from the sulfur chiral center

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones and (R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent at the α-position with high 1,4-chiral induction from the sulfur chiral center in high yields. The adducts were converted to optically active esters and carboxylic acids having a chiral center at the α-position. When this addition reaction was carried out with the ester enolate generated from excess carboxylic acid tert-butyl ester with LDA in the presence of HMPA, the diastereomer of the adduct was obtained. By using the two reaction conditions for the generation of the ester enolates, a new method for asymmetric synthesis of both enantiomers of carboxylic acid derivatives having a substituent at the α-position from the one chiral source, (R)-(−)-chloromethyl p-tolyl sulfoxide, was realized.     

Synthesis of highly functionalized 7-azabicyclo[2.2.1]heptadienes

Highly functionalized 7-azabicyclo[2.2.1]heptadiene derivatives have been synthesized via a [4 + 2] cycloaddition reaction between N-acyl-3,4-disubstituted pyrroles and ethynyl p-tolyl sulfone 5.     

Solvent-induced switching of the macromolecular helicity of poly[(4-carboxyphenyl)acetylene] induced by a single chiral amino alcohol

Cis–transoidal poly[(4-carboxyphenyl)acetylene] (poly- 1 ) complexed with optically active amines and amino alcohols showed an induced circular dichroism (ICD) in the ultraviolet–visible region because of a predominantly one-handed helix formation in water and in dimethyl sulfoxide (DMSO). The Cotton effect signs of the poly- 1 /chiral amino alcohol complexes were inverted in the presence of water, whereas the ICD pattern of the poly- 1 /chiral amine complexes showed no change, regardless of the water content. These results demonstrated that the helix sense of poly- 1 induced by optically active amino alcohols through noncovalent acid–base interactions could be switched by changes in the solvent ratio in the DMSO–water mixtures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3625–3631, 2003     

Asymmetric synthesis of both enantiomers of esters and γ-lactones from optically active 1-chlorovinyl p-tolyl sulfoxides and lithium ester enolates with the formation of a tertiary or a quaternary carbon stereogenic center at the β-position

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position, which were synthesized from aldehydes or unsymmetrical ketones and (R)-(−)-chloromethyl p-tolyl sulfoxide in two or three steps, with the lithium enolate of tert-butyl acetate gave optically active adducts in 99% chiral induction from the sulfur stereogenic center. The adducts were converted to optically active esters, carboxylic acids, and γ-lactones, which have a tertiary or a quaternary carbon stereogenic center at the β-position. A synthesis of optically active spiro-lactones was realized starting from 2-cyclohexenone by this method.     

A new synthesis, including asymmetric synthesis, of alkylidenecyclopropanes by 1,2-CC insertion of cyclobutylmagnesium carbenoides as the key reaction

Treatment of 1-chlorovinyl p-tolyl sulfoxides, derived from ketones and chloromethyl p-tolyl sulfoxide, with lithium enolate of carboxylic acid tert-butyl esters gave adducts in high yields. The adducts were converted to 1-chlorocyclobutyl p-tolyl sulfoxides in four steps in high overall yields. Treatment of the 1-chlorocyclobutyl p-tolyl sulfoxides with cyclopentylmagnesium chloride in THF at −40 °C resulted in the formation of cyclobutylmagnesium carbenoids. The magnesium carbenoid 1,2-CC insertion reaction took place smoothly from the cyclobutylmagnesium carbenoids to afford alkylidenecyclopropanes in good to high yields. An asymmetric synthesis of optically active alkylidenecyclopropane was successfully achieved starting from optically active 1-chlorovinyl p-tolyl sulfoxide.     

The practical procedure for a preparation of 1-chloroalkyl p-tolyl sulfoxides in high optically active form: A very short synthesis of optically active disparlure

A chlorination of optically active alkyl p-tolyl sulfoxides with N-chlorosuccinimide in dichloromethane in the presence of potassium carbonate afforded optically active 1-chloroalkyl p-tolyl sulfoxides in 87–94% ee (88–94% chemical yields). The optically active chloroalkyl sulfoxide was applied to a synthesis of optically active (+)-disparlure.     

Asymmetric oxidation and determination of the configurations of an optically pure sulfoxide and an I-menthoxysulfonium salt of 1,9-bis(methylthio)dibenzothiophene by x-ray crystallographic analysis

1,9-Bis(methylthio)dibenzothiophene (1a) was treated with one equivalent of bromine and pyridine in the presence of l-menthol and then with aqueous sodium hydroxide to give optically active 1-(methylsulfinyl)-9-(methylthio)dibenzothiophene (2a) enriched by the S isomer (ee: 57%). The configuration of optically pure sulfoxide (2a) was determined by X-ray crystallographic analysis to be the S configuration at the sulfinyl sulfur atom. On the other hand, 1-(methyl-l-menthoxysulfonio)-9-(methylthio)dibenzothiophene tetrafluoroborate (4a) was isolated as an intermediate of this asymmetric oxidation in an optically pure form, as yellow crystals. The absolute configuration of this sulfonium salt (4a) was verified by X-ray crystallographic analysis as the R configuration. Optically pure sulfonium salt (4a) also gave partially optically active sulfoxide (2a) with net inversion on its hydrolysis. It was suggested that the hydrolysis reaction of the sulfonium salt (4a) accordingly proceeds, not only via a sulfurane having a simple S_N2 type of geometry but also by a front side attack ofhydroxide anion, with respect to the l-menthoxy group, on sulfur, and the sequential elimination of the l-menthoxy group from the tetracoordinated intermediate. © 1996 John Wiley & Sons, Inc.     

R(-)四氢噻唑-2-硫酮-4-羧酸对D,L-氨基酸酯拆分的研究

以新手性拆分试剂R(-)四氢噻唑-2-硫酮-4-羧酸[简称R(-)TTCA]对D,L-氨基酸酯进行手性拆分,分别得到(R)TTCA氨基酸酯盐1a_1f([α]_D²⁰＝-30.40°～-42.70°)及光学活性氨基酸酯2a-2f,其光学纯度为35.4%～75.8%.由1a_1f在碱存在下分解出2a-2f的对映体3a-3f,光学纯度为39.50%～69.10%.用半经验的量子化学PM3方法研究了氨基的碱性、中间产物铵盐生成热和稳定性.     

Chlor-, Brom- und Iodtrisilane: Synthesen und Si-Kernresonanzspektren

Halogenated trisilanes X_nSi₃H_8−n with X = Cl, Br, I and n = 2–7 as well as the tetrasilanes H₂XSiSiX₂SiX₂SiX₂H have been prepared by dearylation of appropriate aryltrisilanes and aryltetrasilanes (aryl = phenyl, p-tolyl) with either liquid or gaseous hydrogen halides. The compounds have been characterized with elemental analysis as well as ²⁹Si NMR spectroscopy.     

Synthesis of Novel Thioethers and Sulfoxide Compounds

Abstract

Thiosubstituted butadiene and butenyne compounds were synthesized from the reactions of 1,1,3,3,4,4-hexachloro-1-butene or 1,1,2,4,4-pentachlorobuta-1,3-diene with different thiols in EtOH/H₂O solution of NaOH. Tris(thio)substituted butadiene compound was treated with potassium tert-butoxide to obtain tris(thio)substituted butatrienyl halide compound. The novel sulfoxide compounds were synthesized from the reactions of polyhalobutadiene compounds with aliphatic thiols in CHCl₃ with m-CPBA at 0°C. The structures of the novel compounds were characterized by micro analysis, FT-IR, ¹H-NMR, ¹³C-NMR, and MS.     

Novel chiral poly(ester-imide)s with different natural amino acids in the main chain as well as in the side chain: synthesis and characterization

Several novel chiral and potentially biodegradable poly(ester-imide)s (PEI)s bearing natural amino acids in the main chain as well as in the side chain were synthesized via direct polyesterification of N,N'-(pyromellitoyl)-bis-(L-tyrosine dimethyl ester) as a biodegradable optically active phenolic diol and synthesized diacids containing different amino acids and phthalimide group in the side chain. With the aim of tosyl chloride/pyridine/N,N-dimethylformamide (DMF) system as a condensing agent under conventional heating condition, the new optically active PEIs were obtained in good yield and moderate inherent viscosity up to 0.35 dL/g. The obtained polymers were characterized with FT-IR, ¹H NMR, X-ray diffraction (XRD), elemental and thermogravimetric analysis (TGA) techniques. They are readily soluble in amide type solvents such as N,N-dimethylacetamide, DMF, 1-methyl-2-pyrrolidone, dimethyl sulfoxide, and protic solvents such as sulfuric acid. TGA showed that the 10% weight loss temperature in argon atmosphere was around 350 °C, which indicates that the resulting PEIs have a good thermal stability. The presence of amino acid in the PEIs architecture, not only cause to be used as optically active materials but also makes them susceptible to be biocompatible and biodegradable compound.     

A novel synthesis, including asymmetric synthesis, of 2,4,4-trisubstituted 2-cyclopentenones based on the reaction of 1-chlorovinyl p-tolyl sulfoxides with acetonitrile and its homologues

Reaction of 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from chloromethyl p-tolyl sulfoxide and ketones in high overall yields, with cyanomethyllithium (lithium α-carbanion of acetonitrile) gave adducts in high to quantitative yields. The adducts were treated with LDA followed by lithium α-carbanion of the homologues of acetonitrile to give 3,5,5-trisubstituted enaminonitriles in good to high yields. Hydrolysis of the enaminonitriles under acidic conditions gave 2,4,4-trisubstituted 2-cyclopentenones in good yields. By using the optically active chloromethyl p-tolyl sulfoxide and unsymmetrical ketones, this procedure gave the optically pure 2,4,4-trisubstituted 2-cyclopentenones. The scope and limitations of this method and the mechanism of the reactions are also discussed. These procedures offer a new and effective method for the synthesis of 2,4,4-trisubstituted 2-cyclopentenones from four components, ketones, chloromethyl p-tolyl sulfoxide, acetonitrile, and its homologues.