Fluoride-induced nucleophilic (phenylthio)difluoromethylation of carbonyl compounds with [difluoro(phenylthio)methyl]trimethylsilane (TMS-CF2SPh)

A fluoride-induced nucleophilic (phenylthio)difluoromethylation method using TMS-CF₂SPh has been achieved. This new methodology efficiently transfers “PhSCF₂” group into both enolizable and non-enolizable aldehydes and ketones to give corresponding (phenylthio)difluoromethylated alcohols in good to excellent yields. Diphenyldisulfide can also be (phenylthio)difluoromethylated into PhSCF₂SPh in high yield. The reaction with methyl benzoate, however, gives only low yield of (phenylthio)difluoromethyl phenyl ketone. The above-obtained PhSCF₂-containing alcohols can be further transformed into difluoromethyl alcohols using an oxidation-desulfonylation procedure. This new type of nucleophilic (phenylthio)difluoromethylation methodology may have other potential applications in the medicinal and agrochemical fields.     

Synthesis of cis bis-β-lactams via Staudinger cycloaddition reaction using C2-symmetric 1,2-diamines

An efficient stereoselective synthesis of bis-β-lactams via cycloaddition reaction (Staudinger reaction) of ketenes with bisimines derived from C₂-symmetric 1, 2-diamines is described. The reaction provided diastereomeric mixture of meso and C₂-symmetric cis-bis-β-lactams with higher selectivity for meso-bis-β-lactams.     

Thermochemical Properties and Decomposition Kinetics of Ammonium Magnesium Phosphate Monohydrate

Ammonium magnesium phosphate monohydrate NH4MgPO4·H2O was prepared via solid state reaction at room temperature and characterized by XRD, FT-IR and SEM. Thermochemical study was performed by an isoperibol solution calorimeter, non-isothermal measurement was used in a multivariate non-linear regression analysis to determine the kinetic reaction parameters. The results show that the molar enthalpy of reaction above is （28.795 ± 0.182） kJ/mol （298.15 K）, and the standard molar enthalpy of formation of the title complex is （-2185.43 ± 13.80） kJ/mol （298.15 K）. Kinetics analysis shows that the second decomposition of NH4MgPO4·H2O acts as a double-step reaction： an nth-order reaction （Fn） with n=4.28, E1=147.35 kJ/mol, A1=3.63×10^13 s^-1 is followed by a second-order reaction （F2） with E2=212.71 kJ/mol, A2= 1.82 × 10^18 s^-1.     

Hexafluorothioacetone based synthesis of fluorinated heterocycles

Cycloadducts of hexafluorothioacetone (HFTA) were prepared in high yield by a CsF catalyzed reaction between readily available 2,2,4,4-tetrakis-(trifluoromethyl)-1,3-dithietane (as a source of HFTA) with conjugated electron-rich hydrocarbon dienes, such as cyclopentadiene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene or (1Z,3Z)-cyclohepta-1,3-diene. Cyclohexa-1,4- and (1Z,5Z)-cycloocta-1,5-dienes, also undergo the reaction with in situ generated HFTA, but form the products of insertion of HFTA into the C-H bond of the diene as a result of ene-reaction. The highly selective reaction of HFTA with (1Z,3Z,5Z)-cyclohepta-1,3,5-triene and (1Z,3Z,5Z,7Z)-cycloocta-1,3,5,7-tetraene leads to the formation of cycloadducts derived from exclusive addition of thioacetone to the corresponding bicyclic isomers—bicyclo[4.1.0]hepta-2,4-diene or bicyclo[4.2.0]octa-2,4,7-triene, respectively. The corresponding cycloadducts of HFTA with 2,3-dimethylbutadiene-1,3-cyclohexa-1,3-cyclohexa-1,4-dienes and (1Z,3Z,5Z)-cyclohepta-1,3,5-triene were also prepared by direct reaction of sulfur/hexafluoropropene/KF and the corresponding hydrocarbon substrate at 35-45 °C in DMF.     

Robust interface on ENR-50/TiO2 nanohybrid material based sol-gel technique: Insights into synthesis,characterization and applications in optical

In this work, the sol–gel technique was used to prepare a new organic–inorganic hybrid from Epoxidized Natural Rubber (ENR-50) and Titanium dioxide (TiO₂) by blending different content of titania precursors (10, 30, and 50 wt%) with an ENR-50 matrix. A wide range of analyses was conducted to understand the nature of this hybrid and also to evaluate its potential uses in applications required high refractive index such as micro optical and optoelectronic devices. Results indicated that the ring-opening reaction of epoxide groups in ENR-50 increased with the increase of titania content in the hybrid resulting a strong bonding between titania and ENR-50 through TiOC bond, which was observed in FTIR spectrum at 1027–1028 cm⁻¹. It is also observed a slight decrease in the intensity of the amorphous peak along with a new crystalline peak appeared at 2θ = 23 and 27° due to the crystalline nature of titania. The hybrids showed three thermal degradation steps in the range of temperature 76 to 769 °C due to the existence of the Ti moieties with the mixture of polymer chains, which in turn shifted the T_g at 24.3, 26.9 and 28.1 °C for the hybrid at 10, 30, and 50 wt% TiO₂ compared to the T_g of ENR-50 at −18.4 °C respectively. The morphology of the ENR-50 showed clear changes during of the synthesis of ENR-50/TiO₂ hybrids, these changes were proven by SEM, TEM, and AFM analyses. Uv–Vis results showed that the higher wavelength peak at 293 nm has shifted to 296, 298 and 300 nm for the hybrid at 10, 30, and 50 wt% TiO₂ respectively due to the strong interaction between titania precursors and ENR-50 matrix. Furthermore, the hybrids showed good optical transparency in the visible light range.     

Interaction of 2-bromo-7-methyl-5-oxo-5H-1,3,4-thiadiazolo[3,2-α]pyrimidine with methylene-active compounds and acid hydrolysis of its products

Reactions of 2-bromo-7-methyl-5-oxo-5H-1,3,4-thiadiazolo[3,2-a]pyrimidine with sodium derivatives of pentane-2,4-dione, malonodinitrile, Meldrum acid, acetoacetic, cyanoacetic and malonic esters have been shown to give the respective substituted derivatives. Azinyl-ylidene tautomerism has been found to be characteristic of these compounds, the latter existing mainly in the ylidene form. The acid hydrolysis of pentane-2, 5-dione and cyanoacetic and malonic esters derivatives has been investigated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1957–1961, November, 1993     

Pathways of the reactions of nucleophilic addition of H2O and HF molecules to formaldehyde in the gas phase and in the complex with formic acid:ab initio calculations

The gradient pathways of the reactions of nucleophilic addition of H₂O and HF molecules to formaldehyde in the gas phase and in the XH…H₂CO…HC(O)OH complex (X=OH, F) were calculated by theab initio RHF/6-31G^**, MP2(fc)/6-31G^**, and MP2(full)/6-311++G^** methods. Both reactions proceed concertedly. The formation of H-bonded bimolecular pre-reaction complexes is the initial stage of the gas-phase reactions; at the same time, no indications of the formation of stable π-complexes were found on the potential energy surfaces of systems under study. The calculated energy barriers to the gasphase reactions exceed 40 kcal mol⁻¹, while those to reactions in the complex XH…H₂CO…HC(O)OH (X=OH, F) become more than halved. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2146–2154, November, 1998.     

Metalloporphyrins catalyze polyene-polymers to polyepoxides

Polyene polymers [natural rubber (cis-polyisoprene), trans-polyisoprene, and cis-polybutadiene] were transformed to the corresponding polyepoxides which are a polyalcohol and soap precursor. The catalysts used were chloro- or acetato-manganese^(III) tetraphenylporphyrin [Mn^III(TPP)Cl or Mn^III(TPP)OAc] in association with two different oxygen donors, sodium hypochloride and iodosylbenzene (Por, unspecified porphyrinato ligand; TPP, 5,10,15,20-tetraphenylporphyrinato ligand). This transformation in either biphasic system, H₂O(aqua)-CH₂Cl₂ or PhIO(solid)-CH₂Cl₂, was monitored by ¹H-NMR and IR spectroscopy. In both cases the transformation to the polyepoxide was completed within a few hours. © 1992 John Wiley & Sons, Inc.     

Ring-opening reaction of methylenecyclopropanes with LiCl, LiBr or NaI in acetic acid

The methylenecyclopropanes 1 react with LiCl, LiBr or NaI at 80 °C to give the corresponding gem-disubstituted homoallylic halides 2 in good to excellent yields in acetic acid. In some cases, the ring-opening reaction can be completed within 5 min to give the corresponding gem-disubstituted homoallylic halides in high yields.     

Synthetic studies on 3-arylquinazolin-4-ones: intramolecular nucleophilic aromatic substitution reaction of 2-carboxamido-3-arylquinazolin-4-ones and its application to the synthesis of secondary aryl amines

The general synthesis and a novel intramolecular nucleophilic aromatic substitution (S_NAr) reaction of 2-carboxamido-3-arylquinazolin-4-ones, a potentially useful scaffold in the field of medicinal chemistry, are described. The synthetic utility of the S_NAr reaction as a tool for the synthesis of secondary aryl amines, including diaryl amines, is also demonstrated.