Remarkable effect of metal fluoride catalyst on reaction of hexafluoropropene, sulfur and vinyl ethers. Convenient synthesis of 2,2-bis(trifluoromethyl)-4-R-thietanes, 3,3-bis(trifluoromethyl)-5-R-1,2-dithiolanes and 2,2-bis(trifluoromethyl)-4-R-1,3-dithiolanes

It was demonstrated that the outcome of the reaction of hexafluoropropene, sulfur and vinyl ether strongly depends on the catalyst and reaction conditions. The reaction of HFP and S_x leading to the formation of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (1) when it is catalyzed by CsF, proceeds under milder conditions and is easier to control compared to KF catalyzed process. The order of addition of reagents plays a crucial role on the outcome of the reaction. For example, the addition of vinyl ether to pregenerated solution of 1 in DMF solvent results in slow reaction, leading to the corresponding 2,2-bis(trifluoromethyl)-4-R-thietanes in 8-91% yield, and it is catalyzed by either by KF or CsF. The addition of second mole of sulfur to the solution of 2,2-bis(trifluoromethyl)-4-R-thietanes in the presence MF catalyst leads to insertion of sulfur into thietane ring with the formation of the corresponding cyclic disulfides—3,3-bis(trifluoromethyl)-5-R-1,2-dithietanes. On the other hand, the addition of second mole of sulfur to the solution of 1 in DMF in the presence of CsF catalyst, followed by addition of vinyl ether results in exothermic reaction, and it produces the corresponding 2,2-bis(trifluoromethyl)-4-alkoxy-1,3-dithiolanes in good yield.It was also demonstrated that 2,2-bis(trifluoromethyl)-4-R-thietanes can undergo disproportionation under action of fluoride anion, producing a mixture of the corresponding 1,2-dithiolane and CF₂C(CF₃)CH₂CFHOR. The nucleophilic attack of fluoride anion in this case proceeds selectively on the carbon of the thietane ring, bearing alkoxy group.The structure of 2,2-bis(trifluoromethyl)-4-R-thietanes forming as the result of 2 + 2 cycloaddition reaction between hexafluorothioacetone generated “in situ” from dimer 1 and vinyl ether was firmly supported by single crystal X-ray diffraction data, obtained for thietane bearing t-BuO-group.     

Novel method for the synthesis of (trifluoromethyl)oxirane

The reaction of 3,3,3-trifluoropropene with N-bromosuccinimide in acetic acid at 65—70 °C affords 3-acetoxy-2-bromo-1,1,1-trifluoropropane. When treated with an alkali, the latter is readily converted into (trifluoromethyl)oxirane.     

Reactions of polyfluorinated thietanes: Selective synthesis of 4-R-2,2-bis(trifluoromethyl)thietane-1-S-oxides and 2-substituted 5-fluoro-4-(trifluoromethyl)-2,3-dihydrothiophenes

Oxidation of 4-substituted 2,2-bis(trifluoromethyl)thietanes by m-chloroperoxybenzoic acid results in selective formation of the corresponding S-oxides in 65-86% yield. Oxidation of 4-C₂H₅S-2,2-bis(trifluoromethyl)thietane under mild conditions led to selective formation of 4-C₂H₅SO₂-2,2-bis(trifluoromethyl)thietane, which under more rigorous conditions was selectively converted into trans-4-C₂H₅SO₂-2,2-bis(trifluoromethyl)thietane-1-S-oxide. Reaction of 4-substituted 2,2-bis(trifluoromethyl)thietanes with activated aluminum powder results in a highly selective ring expansion process, producing the corresponding 5-fluoro-4-(trifluoromethyl)-2,3-dihydro-2-alkoxythiophenes in 58-93% yield. These compounds were also prepared in 61-85% yield using a “one-pot” procedure, starting from sulfur, hexafluoropropene and the corresponding vinyl ether without isolation of any intermediates. Both 2-i-C₃H₇O- and 2-t-C₄H₉O- 5-fluoro-4-(trifluoromethyl)-2,3-dihydrothiophenes were converted into 2-fluoro-3-trifluormethylthiophene by reaction with P₂O₅.     

相转移催化下二醇类及肟类的选择性间接电氧化

在对Cr(VI)/Cr(III)体系在相转移催化下对醇类的选择性间接电氧化进行了探讨,发现共醇类能被高产率、选择性地氧化为相应的羰基化合物,而非苄醇类则无此效果的基础上,本文是在此基础上,对分子内含有苄醇羟基和另一个非苄醇羟基的二醇类及肟类化合物进行了选择性电氧化的探讨,结果发现,在本实验条件下,共醇羟基能被选择性地氧化为相应的羰基,而分子内共存的非苄醇羟基几乎不受影响;各种肟类化合物也能有选择地氧化裂解为相应的羰基化合物,而不被深度氧化。     

Difluoromethylation of some C-H acids with chlorodifluoromethane under conditions of phase transfer catalysis (PTC)

Selected C-H acids react with difluorocarbene generated from chlorodifluoromethane with concentrated aqueous solution of sodium hydroxide, and a catalyst, benzyltriethylammonium chloride (TEBAC) in benzene or THF affording C-difluoromethyl substituted derivatives. This process is restricted to C-H acids of pK_a ≅ 16.3-19.1. The observed facts are rationalized.     

Synthesis of 1,1-bis(trifluoromethyl)alkyl isocyanates, carbamates, and ureas

A convenient preparative method for the synthesis of 1,1-bis(trifluoromethyl)alkyl isocyanates was proposed. The reactions of the isocyanates with alcohols, phenols, and alkyl-, aryl-, and hetarylamines were studied. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1205–1209, July, 2000.     

2,2-Bis(3-allyl-4-hydroxyphenyl)hexafluoropropane and fluorosiloxane as coating materials for nerve agent sensors

A simpler technique for the synthesis of 2,2-bis(4-allyoxyphenyl)hexafluoropropane has been achieved from 4,4′-(hexafluoroisopropylidene)diphenol for obtaining 2,2-bis(3-allyl-4-hydroxyphenyl)hexafluoropropane. This monomer and its corresponding hybrid organic/inorganic siloxane polymer are successfully used as a coating material for the detection of toxic chemical warfare agents.     

Reactions of tetrakis(trifluoromethyl) diphosphine and bis(trifluoromethyl) phosphine with ruthenium carbonyl clusters; X-ray structure of tetraruthenium carbonyl cluster derivatives

Reaction of [Ru₃(CO)₁₂ with (CF₃)₂P---P(CF₃)₂ in p-xylene at 140°C yielded the compounds [Ru₄(CO)₁₃{μ-P(CF₃)₂}₂] (1), [Ru₄(CO)₁₄{μ-P(CF₃)₂}₂] (2) and [Ru₄(CO)₁₁{μ-P(CF₃)₂}₄] (3). Reaction with [(μ-H)₄Ru₄(CO)₁₂] under similar conditions yielded [(μ-H)₃Ru₄(CO)₁₂{μ-P(CF₃)₂}] (4). All four compounds have been characterised by X-ray crystallography. The fluxional behaviour of the hydrides in 4 has also been studied by variable-temperature NMR spectroscopy. Compounds 1, 2 and 4 were also obtained from the reactions of Ru₃(CO)₁₂ with (CF₃)₂PH in dichloromethane at 80°C.     

Novel perfluoroalkenylphosphonates and iodoperfluoroalkenes from 3,3 -bis (trifluoromethyl) -1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene

The reaction of 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene with tris(trimethylsilyl)phosphite gave fluorotrimethylsilane and the respective (Z)-alkenylbis(trimethylsilyl)phosphonates. In one case hydrolysis afforded the free phosphonic acid (CF₃)₃CCF = CFP(O) (OH)₂. Using tri-n-butylphosphine and boron trifluoride etherate, 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene were converted into the corresponding phosphonium tetrafluoroborates, which when reacted further with iodine in the presence of Na₂CO₃ gave the iodo derivatives (CF₃)₃CCF = CFI and C₄F₉OCF = CFI.     

New partially fluorinated epoxides by oxidation of olefins with sodium hypohalites under phase transfer catalysis

Partially fluorinated epoxides can be readily prepared by oxidation of the corresponding olefins by NaOCl (or NaOBr) under phase transfer catalysis (PTC) conditions. Oxidation of CH₂C(CF₃)₂ at 0-5 °C leads to the formation of 2,2-bis(trifluoromethyl)oxirane in 65-75% yield. (CF₃)₂CCHCH₂X (X=Cl or Br) were converted into the corresponding epoxides in 24-31% yield by the action of NaOCl and NaOBr, respectively. Baylis-Hillman adducts of fluorinated ketones and esters of acrylic acid CH₂C[C(OH)(CF₂X)Y][C(O)OR] [X=F or Cl, Y=CF₃, CF₂Cl or C(O)OCH₃ and R=CH₃ or C(CH₃)₃] were converted into α-hydroxyepoxides in 47-84% yield under action of NaOCl in the presence of PT catalyst. Oxidation of tert-butyl ester of α-trifluoromethylacrylic acid by NaOCl rapidly proceeds at ambient temperature with formation of epoxide in 75% yield. Oxidation of (C₂F₅)₂CCHC₃F₇ results in the high yield formation of trisubstituted epoxide.     

Synthesis of diethers derived from furoin by phase transfer catalysis under microwave irradiation

A series of new diethers were obtained by alkylation of furoin under microwave irradiation (MWI) in phase transfer catalysis (PTC) conditions. The products of alkyl halides were synthesized in good yields (>75%) within a few minutes, and the products of dihalides were synthesized in fair yields (about 45%). The yields are dramatically improved compared to conventional heating under the same conditions, in spite of similar profiles of rising in temperature.     

Novel β-hydroxy-β-bis(trifluoromethyl) imines

Selected imines reacted with hexafluoroacetone non-catalyzed at ambient temperature to give β-hydroxy-β-bis(trifluoromethyl) imines in good to excellent yields. For the imines of acetone, pentan-3-one, and of cyclohexanone a 1:2 reaction was observed giving iminodiols; for N,N′-bis(propylidene)ethylene diamine an iminotetrol was formed. The diol derivative of N-isopropyl-propylidene amine could be deprotonated and O-methylated furnishing the respective ethers. Hexafluoropropylidene amine reacted with N-isopropyl-propylidene amine, unlike hexafluoroacetone, in a 1:1 manner to form an amino-imino alcohol which in its turn is able to add hexafluoroacetone. The imines of acetophenone, trifluoroacetone, 2,4-dimethyl-pentan-3-one, 2,6-dimethyl-cyclohexanone and of acetaldehyde added hexafluoroacetone to furnish β-iminoalcohols. A multifunctional β-hydroxy enaminone was obtained from 4-isopropylamino-pent-3-en-2-one. The molecular structures of the novel β-hydroxy-β-bis(trifluoromethyl) imines exhibit strong (R)N?HO hydrogen bonds.     

Preparation and characterisation of novel random copoly(arylene ether-thioether ketone)s containing 2,2-bis(4-phenylene)propane units

This study investigates on the preparation and characterisation of new random copolymers containing the monomeric units of a poly(arylene ether ketone) (PEAEK) and a poly(arylene thioether ketone) (PTATK) previously synthesised by our group. The syntheses were performed using a one-pot polymerisation method starting from 4,4′-difluorobenzophenone, bis(N,N-dimethyl-S-carbamate) of 2,2-bis(4-mercaptophenyl)propane (MBTA) and bisphenol A (BPA). Different mole percentages of BPA with respect to MBTA, varying from 20% to 80%, were used. The copolymers, obtained in good yields, have molecular weights in the range from 19,000 to 32,000 as determined by GPC. The structural proof is provided by ¹H NMR spectroscopy. The TGA analysis shows that the high stability of PEAEK is only slightly affected by the introduction of the PTATK co-units in the chain. Indeed, the presence of sulphur atoms induces an initial degradation process at temperatures slightly lower than that of PEAEK, but in a second stage tends to improve the formation of crosslinkings. Moreover, the copolymers with an amount of PEAEK equal to 40 and 20 mol% show a small crystallinity, due to the presence of PTATK units. The T_g values are not affected by the composition of copolymers. Therefore, the presence of sulphur atoms in the polymer backbone does not significantly modify the PEAEK characteristics, whereas can induce important new properties, such as better flame resistance or higher refractive index.     

SelectiveN(1)-arylation of benzotriazole with activated aryl halides under conditions of phase transfer catalysis

Arylation of 1H-1,2,3-benzotriazole, with activated aryl halides in a medium of aromatic hydrocarbons under conditions of phase transfer catalysis with the use of inorganic bases and cetyltrimethylammonium bromide as a phase-transfer catalyst was studied. Arylation affords bothN(1)- andN(2)-arylation products. Their ratio depends on the nature of the base and the reactivity of the arylating agent. In the presence of catalytic amounts of copper phenylcyclopropanecarboxylate, arylation proceeds regioselectively at the N(1) atom. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1553–1556, August, 1999.     

Fluorous biphasic catalysis with dirhodium(II) perfluorocarboxylates: selective silylation of alcohols under fluorous biphasic conditions

Dirhodium(II) perfluorocarboxylates bearing C7–C13 perfluoroalkyl chains have been prepared and used as catalysts under fluorous biphasic conditions. They were found to be active and recyclable catalysts for the silylation of alcohols with triethylsilane. Hydrophobic, primary alcohols are preferentially silylated by the fluorous biphasic catalytic system in comparison with hydrophilic or secondary ones. This opens the way to the development of selective silylation protocols.     

Synthesis and characterizations of 3,3′-bis(diphenylphosphinoamine)-2,2′-bipyridine and 3,3′-bis(diphenylphosphinite)-2,2′-bipyridine and their chalcogenides

New bis(phosphinoamine) and bis(phosphinite) derivatives of 2,2′-bipyridine were prepared through a single step reaction of 3,3′-diamino-2,2′-bipyridine or 3,3′-dihydroxy-2,2′-bipyridine with diphenylchlorophosphine, respectively. Their P = E chalcogenides (E = O, S, Se) were also prepared. All the new compounds were characterized by elemental analysis, IR and NMR spectroscopies. The molecular structure of 3,3′-bis(diphenylthiophosphinite)-2,2′-bipyridine was elucidated by single-crystal X-ray crystallography.     

Heterocyclization of 1,1-dicyano-2-(trifluoromethyl)ethylenes with 1,3,3-trimethyl-3,4-dihydroisoquinoline and its derivatives

1,3,3-Trimethyl-3,4-dihydroisoquinolines react with 1,1-dicyano-2,2-bis(trifluoromethyl)ethylene to give 4-amino-6,6-dimethyl-2,2-bis(trifluoromethyl)-3-cyano-6,7-dihydro-2H-benzo[a]quinolizines. The reaction of 3,3-dimethyl-1-cyanomethylidene-1,2,3,4-tetrahydroisoquinoline and the methyl ester of 3,3-dicyano-2-(trifluoromethyl)acrylic acid leads to 5,5-dimethyl-3-oxo-2-(trifluoromethyl)-2-(dicyanomethyl)-2,3,5,6-tetrahydropyrrolo[2,1-a]isoquinoline.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1888–1892, August, 1992.     

Efficient synthesis of polyethers from isosorbide by microwave-assisted phase transfer catalysis

Polyetherification of isosorbide with 1,8-dibromo or dimesyl octane was realized under phase transfer catalysis with increased efficiency when performed under microwave activation. In addition to rate increase in the reaction, microwave effects on polymer structures (as determined by MALDI-TOFMS) were observed. Polymers with higher molecular weights with the presence of ethylenic groups as chain terminations were thus obtained, unlike to conventional heating where shorter hydroxylated compounds were achieved.     

Spectroscopic, thermal and structural studies of cocrystal of 2,2′-diamino-4,4′-bis(1,3-thiazole) with 4,4′-bipyridine, 1,2-bis(4-pyridyl)ethylene and 1,3-bis(4-pyridyl)propane

Three new cocrystals based upon 2,2′-diamino-4,4′-bis(1,3-thiazole) (DABTZ) with 4,4′-bipyridine (4,4′-bipy), 1,2-bis(4-pyridyl)ethylene (bpe) and 1,3-bis(4-pyridyl)propane (bpp): [(DABTZ) (4,4′-bipy)], [(DABTZ) (bpe)] and [(DABTZ) (bpp)] have been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy and studied by thermal and X-ray crystallography. Self-assembly of these compounds in the solid state is likely caused by both hydrogen bonding, and π-π stacking.     

De novo synthesis of 2,2-bis(dimethylamino)-3-alkyl or benzyl 2,3-dihydroquinazolin-4(1H)-one compounds

A new versatile and efficient strategy for the synthesis of 2,2-bis(dimethylamino)-3-alkyl or benzyl 2,3-dihydroquinazoline-4(1H)-one compounds has been developed by one-pot multicomponent reaction with isatoic anhydride, amines followed by in situ-generated Vilsmeier reagent. The reaction has also been studied with different amines and solvents.