Synthesis of 3,3,3-trifluoropropene from vinylidene fluoride

3,3,3-Trifluoropropene is obtained under mild conditions via 3,3,3-trifluoropropyl acetate or 3,3,3-trifluoropropyl methyl ether as key intermediates. The intermediates were prepared by conjugate addition of FCH₂OR (R = COCH₃, CH₃) generated $\text{in situ}$ from HF, paraformaldehyde and HOR to vinylidene fluoride.     

Poly(ethylene imine) hybrids containing polyhedral oligomeric silsesquioxanes: Preparation, structure and properties

Both octaglycidyletherpropyl polyhedral oligomeric silsesquioxane and hepta(3,3,3-trifluoropropyl)glycidyletherpropyl polyhedral oligomeric silsesquioxane were synthesized via the hydrosilylation reactions between octahydrosilsesquioxane [and/or hepta(3,3,3-trifluoropropyl)hydrosilsesquioxane] and allyl glycidyl ether. The polyhedral oligomeric silsesquioxane (POSS) macromers were characterized by means of Fourier transform infrared and nuclear magnetic resonance spectroscopy. The inter-component macromolecular reactions between the POSS macromers and poly(ethylene imine) (PEI) were employed to prepare the POSS-containing organic-inorganic PEI hybrids. The inclusion of octaglycidyletherpropyl POSS into PEI results in the formation of the organic-inorganic hybrid networks whereas the introducing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS to PEI affords the linear POSS-grafted PEI copolymers. Differential scanning calorimetry and thermogravimetric analysis show that the POSS-containing PEI hybrids displayed increased glass transition temperatures (T_g’s) and enhanced thermal stability compared to the plain PEI. These PEI hybrid composites can be significantly swollen with water without dissolving, suggesting the formation of hydrogels. The PEI hydrogels containing octaglycidyletherpropyl POSS is in reality the chemically-crosslinked hydrogels whereas the those containing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS displayed the behavior of physical hydrogels. The formation of physical hydrogels is ascribed to the microphase-separated morphology in the hybrids. In addition, the hybrids containing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS exhibited the typical amphiphilicity as evidenced by the increase in surface hydrophobilicity.     

Sodium dithionite initiated addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to β-pinene: Synthesis of CF3-substituted terpenoids

Sodium dithionite effectively promotes the addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to the exocyclic double bond of β-pinene. The reaction proceeded in an MeCN/H₂O system to give almost quantitatively a 1:1 mixture of diastereoisomers of 4-(2-bromoisopropyl)-1-(2-chloro-3,3,3-trifluoropropyl)-cyclohexene (1). Dehydrobromination of 1 with pyridine gave a mixture of regioisomeric dienes 2 and 3, while treatment with DBU at elevated temperature resulted in total dehydrohalogenation to give trienes 4 and 5. Reduction of 1 with Bu₃SnH gave 1-(2-chloro-3,3,3-trifluoropropyl)-4-(isopropyl)cyclohexene (6) which on dehydrochlorination with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) afforded conjugated diene, 4-isopropyl-1-(trans-3,3,3-trifluoropropenyl)-cyclohexene (7), with 50% overall yield. All the transformations proceeded with the retention of configuration at the carbon atom C-4 and the final compound 7 exhibited high optical activity.     

Fluorine-containing dialkoxysilanes. The formation of complexes with aminopropyltriethoxysilane and production of transparent films

Three dialkoxysilanes with fluorine-containing groups were synthesized: methyl(3,3,3-trifluoropropyl)dimethoxysilane, methyl(3,3,3-trifluoropropyl)bis(2,2,2-trifluoroethoxy)silane, and methyl(2,2,2-trifluoro-1-trifluoromethylethoxymethyl)bis(2,2,2-trifluoro-1-trifluoro-methylethoxy)silane. It was found by IR and ²⁹Si NMR spectroscopies that (3-aminopropyl)-triethoxysilane forms complexes with the indicated compounds, which are hydrolyzed in the presence of air moisture to form films of high optical quality.     

Synthesis of fluorinated acyclic nucleoside phosphonates with 5-azacytosine base moiety

With respect to the strong antiviral activity of (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine various types of its side chain fluorinated analogues were prepared. The title compound, (S)-1-[3-fluoro-2-(phosphonomethoxy)propyl]-5-azacytosine (FPMP-5-azaC) was synthesised by the condensation reaction of (S)-2-[(diisopropoxyphosphoryl)methoxy)-3-fluoropropyl p-toluenesulfonate with a sodium salt of 5-azacytosine followed by separation of appropriate N¹ and O² regioisomers and ester hydrolysis. Transformations of FPMP-5-azaC to its 5,6-dihydro-5-azacytosine counterpart, amino acid phosphoramidate prodrugs and systems with an annelated five-membered imidazole ring, i.e. imidazo [1,2-a][1,3,5]triazine derivatives were also carried out. 1-(2-Phosphonomethoxy-3,3,3-trifluoropropyl)-5-azacytosine was prepared from 5-azacytosine and trifluoromethyloxirane to form 1-(3,3,3-trifluoro-2-hydroxypropyl)-5-azacytosine which was treated with diisopropyl bromomethanephosphonate followed by deprotection of esters. Antiviral activity of all newly prepared compounds was studied. FPMP-5-azaC diisopropyl ester inhibited the replication of herpes viruses with EC₅₀ values that were about three times higher than that of the reference anti-HCMV drug ganciclovir without displaying cytotoxicity.     

A synthesis of the γ-secretase inhibitor BMS-708163

A concise, convergent racemic synthesis of BMS-708163 is reported. Two fragments consisting of N-4-chlorophenylsulfonyl-3,3,3-trifluorpropylglycine and a 1,2,4-oxadiazole derivative of 2-fluorobenzyl alcohol were prepared in separate pots and then coupled together via a Mitsunobu reaction. Since a convenient chiral synthesis of optically pure (d)-3,3,3-trifluoropropyl glycine methyl ester was developed using Schöllkopf reagent alkylation, this methodology can also be adopted for the enantioselective synthesis of BMS-708163.     

Nucleophilic substitution of bromine in vicinal bromotrifluoroalkylamines

SecondaryN-(2-bromo-3,3,3-trifluoropropyl)-N-alkylamines cyclize under the action of bases to yield aziridines. TertiaryN-(2-bromo-3,3,3-trifluoropropyl)amines react with S-nucleophiles to give products of bromine substitution.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 955–957, May, 1994.     

Catalyst-free synthesis of coumarin-, quinolone- and pyridine-annulated oxazole derivatives

An efficient approach for the synthesis of coumarin-, quinolone- and pyridine-annulated oxazole derivatives has been achieved by direct base-mediated intramolecular carbon–oxygen bond formation in a transition metal catalyst-free protocol. Intramolecular cyclization of o-bromoamides in DMSO in the presence of Cs₂CO₃ at 130 °C affords heterocycle-annulated oxazole derivatives in high yields via a nucleophilic addition of amide to form the C–O bond.     

Synthesis and structure of diethyl (1-benzyloxycarbonylamino-1-carboranyl-3,3,3-trifluoropropyl)phosphonate

A reaction of C-carboranylmethylmagnesium bromide with diethyl (N-benzyloxycarbonyl-2,2,2-trifluoroethaneimidoyl)phosphonate gave P- and N-protected aminophosphonic acid, an organophosphorus analog of alanine. The phosphonate was characterized by ¹H, ¹⁹F, and ³¹P NMR spectroscopy. X-ray diffraction analysis of diethyl (1-benzyloxycarbonylamino-1-carboranyl-3,3,3-trifluoropropyl)phosphonate showed that the molecules form dimers in crystals due to the intermolecular hydrogen bond.     

Salze von Halogenophosphorsäuren. XV. Sulfan-α,ω-diyl-bis(fluorodithiophosphate), Reaktionsprodukte des Fluoridabbaus schwefelreicher Phosphorsulfide

Salts of Halogenophosphoric Acids. XV. Sulfane-α,ω-diyl-bis(fluorodithiophosphates). Products of the Fluoride Degradation of Sulfur-rich Phosphorus Sulfides By the reaction of sulfur-rich phosphorus sulfides ?P₄S_10+m”? (m = 0,5 to 6) with fluorides MF (M = Na, K, NH₄) in acetonitrile or 1,2-dimethoxy-ethane mixtures of sulfane-α,ω-diyl-bis(fluorodithiophosphates) [(PFS₂)₂S_n]^2? (n = 1 to 8) are formed. The average chain length n of the sulfane derivatives depends on the S:P ratio of the starting phosphorus sulfides. The compounds are identified by ¹⁹F and ³¹P n.m.r. spectroscopy.     

Subspeciation of nickel disulfide by carbon paste electrode voltammetry catalyzed by Ni2+

In subspeciation of sulfidic nickel, carbon paste electrode voltammetry was developed for the specific determination of Ni₃S₂ or NiS, but NiS₂ was found to be unreactive. Ni²⁺ in pH 7.2 acetate solution was able to catalyze NiS₂ to undergo redox reactions. The cyclic voltammogram showed two anodic peaks at –0.3 and +0.7 V and a cathodic peak at –0.6 V. The first anodic peak at –0.3 V and the cathodic peak were common among the three nickel sulfides, but the second anodic peak at +0.7 V was unique to NiS₂. This peak current gave a linear dose response to NiS₂ from 40 to 610 μg, with a correlation coefficient of 0.994, and a detection limit of 40 μg.     

Experimental and DFT study of the conversion of ephedrine derivatives into oxazolidinones. Double SN2 mechanism against SN1 mechanism

Sulfonation of the N-Boc derivatives of 1,2-aminoalcohols, such as ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, thiomicamine, and chloramphenicol yields a mixture of the corresponding oxazolidinones with inversion (erythro derivatives) and/or retention of configuration (threo derivatives)at C5. We suggest a competition between two mechanisms: an intramolecular S_N2 process initiated by attack of the carbonyl oxygen of the Boc group to the benzylic carbon and the other one through a double S_N2 process. In the erythro derivatives the first mechanism is predominant, while in the threo derivatives both mechanisms have similar energy. This hypothesis is supported by theoretical calculations and additional experimental assays.     

Dimethyl(3,3,3-trifluoropropyl)silyldiethylamine—A new silylating agent for the derivatization of β-blockers and β-agonists in environmental samples

Research into alternative derivatizing agents remains a major task in the trace analysis of polar compounds using GC. DIMETRIS (dimethyl(3,3,3-trifluoropropyl)silyldiethylamine) is a new and interesting proposition in this field. This agent possesses strong nucleophilic properties and reacts selectively with hydroxyl groups. The derivatization reaction takes place in the absence of any catalysts. The derivatives possess good chromatographic properties and are easily detected by mass spectrometry. By introducing fluorine atoms into the structure of the derivatives, we were able to use an electron-capture detector for their GC determination. No degradation of new derivatives was observed after seven days of storage in a refrigerator or during the GC analyses. Unlike a number of acylation agents, DIMETRIS does not corrode the analytical equipment. In this work β-blockers and β-agonists were used for testing the derivatizing properties of DIMETRIS. Derivatization of these drugs was optimal at 30 °C for 30 min. The method quantification limits of the target compounds determined in tap water samples by SPE-GC–MS(SIM) ranged from 3 to 40 ng L⁻¹ and resembled those obtained with samples derivatized using a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1% chlorotrimethylsilane (TMCS) (hitherto regarded as optimal). This work confirmed that DIMETRIS is suitable for the trace analysis of pharmaceuticals in natural samples and provides an interesting alternative to silylating and acylating agents.     

含氟环形硅氧烷的立体异构和稳定性

文献曾报道, 1,3,5-三(3,3,3-三氟丙基)-1,3,5-三甲基环三硅氧烷(简称D^F~3)有两种立体异构体, 即顺式和反式。1,3,5,7-四(3,3,3-三氟丙基)-1,3,5,7-四硅氧烷(简称D^F~4)有四种异构体。但未报道其结构特点。本文试图进一步探讨D^F~3和D^F~4的立体异构体的结构和稳定性。     

Reaction of singlet oxygen with some benzylic sulfides

Product distribution, total quenching rate (k_T), and rate of chemical reaction (k_r) with singlet oxygen have been determined for some alkyl, benzyl, α-methylbenzyl, and cumyl sulfides. Their contributions depend on the steric hindering around the sulfur atom. In protic solvents, the sulfoxide is the main product via a hydrogen-bonded persulfoxide. In apolar solvents, intramolecular α-H abstraction leads to oxidative C-S bond cleavage, with varying efficiency. The behavior of sulfides is compared to that of alkenes and amines.     

Synthesis, characterization and in vitro oxidative stability of poly(3,3,3-trifluoropropyl)methylsiloxane modified polyurethaneurea

A series of α,ω-bis(3-hydroxypropyl)-poly[(3,3,3-trifluoropropyl)methylsiloxane] (FPS) with different molecular weights were synthesized and characterized, then the FPS modified polyurethaneurea (FSPUU) elastomers were further synthesized with poly(tetramethylene glycol)/FPS as soft segments and 4,4′-diphenylmethane diisocyanate/ethylene diamine as hard segments. The surface properties of the FSPUU films were measured. It was found that the surface hydrophobicity of these FSPUU films was enhanced with increasing the molecular weight of FPS, due to the enrichment of FPS segments at the surface region. Oxidative stability of the FSPUU films was examined in vitro by immersing the films with 200 μm thickness in oxidative solution (H₂O₂/CoCl₂) for 21 days. The experimental results showed that the degree of degradation of all FSPUU films was lower than that of polydimethylsiloxane modified polyurethaneurea (MSPUU), and the oxidative stability of these FSPUU films was fair enhanced with increasing the molecular weight of FPS, which could be attributed to the lowering of swelling ratios in H₂O and 20% H₂O₂, as well as the permeation rate of H₂O in FSPUU films. Furthermore, the tensile strength of all FSPUU films is higher than that of MSPUU film.     

Structures of four types of novel high-valent manganese complexes obtained by the reactions of KMnO4 with tridentate Schiff base ligands

X-ray structure analysis revealed that four types of novel manganese complexes, Mn^IV(N-EtO-sal)₂, Mn^III(N-PhO-sal)(L), [Mn^IV(5,6-Benzo-L)₂(μ-O)]₂ and Mn^III(L-4-Me)₃ have been found to be obtained by the reactions of KMnO₄ with various tridentate Schiff base ligands (N-EtOH-salH, N-PhOH-salH and its derivatives) in dry MeCN, where N-EtOH-salH, N-PhOH-salH, LH, 5,6-Benzo-LH and L-4-MeH denote N-2-hydroxyethyl-salicylideneamine, N-2-hydroxyphenyl-salicylideneamine, 2-(2-hydroxyphenyl)-benzoxazole 2-(2-hydroxynaphthyl)-benzoxazole and 2-(2-hydroxyphenyl)-5-methylbenzoxazole, respectively. The reactions of KMnO₄ and N-PhOH-salH and its derivatives have especially been found to afford benzoxazole derivatives which may be formed by intramolecular oxidative coupling between the phenolic oxygen atom of aminophenol moiety and the carbon atom of imine moiety.     

Rhodium(II)‐Catalyzed Inter‐ and Intramolecular Cyclopropanations with Diazo Compounds and Phenyliodonium Ylides: Synthesis and Chiral Analysis

Different classes of cyclopropanes derived from Meldrum's acid (=2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione; 4 ), dimethyl malonate ( 5 ), 2‐diazo‐3‐(silyloxy)but‐3‐enoate 16 , 2‐diazo‐3,3,3‐trifluoropropanoate 18 , diazo(triethylsilyl)acetate 24a , and diazo(dimethylphenylsilyl)acetate 24b were prepared via dirhodium(II)‐catalyzed intermolecular cyclopropanation of a set of olefins 3 (Schemes 1 and 4–6). The reactions proceeded with either diazo‐free phenyliodonium ylides or diazo compounds affording the desired cyclopropane derivatives in either racemic or enantiomer‐enriched forms. The intramolecular cyclopropanation of allyl diazo(triethylsilyl)acetates 28, 30 , and 33 were carried out in the presence of the chiral dirhodium(II) catalyst [Rh₂{(S)‐nttl)₄}] ( 9 ) in toluene to afford the corresponding cyclopropane derivatives 29, 31 and 34 with up to 37% ee (Scheme 7). An efficient enantioselective chiral separation method based on enantioselective GC and HPLC was developed. The method provides information about the chemical yields of the cyclopropane derivatives, enantioselectivity, substrate specifity, and catalytic activity of the chiral catalysts used in the inter‐ and intramolecular cyclopropanation reactions and avoids time‐consuming workup procedures.     

Corrosion inhibition of carbon steel in hydrochloric acid 0.5 M by hexa methylene diamine tetramethyl-phosphonic acid

The efficiency of hexa methylene diamine tetra methyl-phosphonic acid (HMDTMP), as corrosion inhibitor for carbon steel in 0.5 M HCl, has been determined by gravimetric and electrochemical measurements. Polarization curves indicate that the compound is a mixed inhibitor, affecting both cathodic and anodic corrosion currents. Adsorption of HMDTMP derivatives on the carbon steel surface is in agreement with the Langmuir adsorption isotherm model, and the calculated Gibbs free energy value confirms the chemical nature of the adsorption. EIS results show that the charge in the impedance parameters (R_t and C_dl) with concentrations of HMDTMP is indicative. The adsorption of this molecule leads to the formation of a protective layer on carbon steel surface. The electrochemical results have also been supplemented by surface morphological studies.     

Indium chloride catalyzed intramolecular cyclization of N-aryl imines: synthesis of pyrrolo[2,3-d]pyrimidine annulated tetrahydroquinoline derivatives

The intramolecular aza Diels-Alder cyclization reaction of aldimines derived from aromatic amines and N-prenyl/cinnamyl derivatives of pyrrolo[2,3-d]pyrimidine were efficiently catalyzed by InCl₃ to afford the corresponding tetrahydroquinoline derivatives in good yields.