Trifluoromethylation of carbon and boron with CF3SiMe3/NMe4F: formation of NMe4[trans-CF3CFCFB(CF3)3]

Trimethylamine-trifluoroethenyl-bis(trifluoromethyl)borane [F₂CCF(CF₃)₂B·NMe₃] (1) reacts with NMe₄[(CF₃)₂SiMe₃] in THF solution to form trimethylamine-bis(trifluoromethyl)pentafluoropropenylborane [trans-CF₃CFCF(CF₃)₂B·NMe₃] (3), the fluoroborate NMe₄[trans-CF₃CFCF(CF₃)₂BF] (4), the novel borates NMe₄[trans-CF₃CFCFB(CF₃)₃] (5) and NMe₄[cyclo-(CF₃)₂BCF₂CFCF₂CF₃] (6).     

Perfluoro-4-methyl-1,3-dioxole: a new monomer for high-Tg amorphous fluoropolymers

A 4-Chloro-5-trifluoromethyl-2,2,4-trifluoro-1,3-dioxolane (1) was synthesised by reaction of CF₂(OF)₂ with CF₃CHCFCl; the elimination of HCl from (1) in basic conditions led to the formation of dioxole perfluoro-4-methyl-1,3-dioxole (2). Both these synthetic steps gave the corresponding product in high yield.A new synthetic route for the preparation of CF₃CHCFCl, starting from CF₂ClBr and CH₂CF₂, together with some examples of polymerisation products obtained by reaction of dioxole (2) with fluoroolefins are also reported.     

Synthesis and selective silylation of ω-hydroxy functionalized (η-alkenyl)carbene complexes of chromium(0) and tungsten(0) Part 11. The chemistry of metallacyclic alkenylcarbene complexes

Tungsten(0) carbene complexes of the type (OC)₅WC(NMeCH₂CHCHCH₂OH)R 2 (R=Me: 2a; R=Ph: 2b) were generated by aminolysis of (OC)₅WC(OMe)R with cis-NHMeCH₂CHCHCH₂OH. Like their Cr-congeners 1, complexes 2 exist at room temperature as mixtures of Z- and E-isomers with regard to the C-N bond. The metallacyclic complexes (OC)₄WC(η²-NMeCH₂CHCHCH₂OH)R (4) were obtained in good yields upon photo-decarbonylation of 2. Deprotonation/silylation of the complexes (OC)₄MC(η²-NMeCH₂CHCHCH₂OH)Me (M=Cr: 3a; M=W: 4a) with one equivalent of ⁿBuLi/Me₃SiCl gave (OC)₄MC(η²-NMeCH₂CHCHCH₂OSiMe₃)CH₃ (M=Cr: 5; M=W: 6), whereas with two equivalents of ⁿBuLi/Me₃SiCl complexes (OC)₄MC(η²-NMeCH₂CHCHCH₂OSiMe₃)CH₂SiMe₃ (M=Cr: 7; M=W: 8) were formed. Hydrolysis of the latter yielded selectively (OC)₄MC(η²-NMeCH₂CHCHCH₂OH)CH₂SiMe₃ (M=Cr: 9; M=W: 10). The complexes 1-10 were analyzed in solution by one- and two-dimensional NMR spectroscopy (¹H, ¹³C, ²⁹Si, ¹H/¹H COSY, ¹H/¹H NOESY, ¹³C/¹H HETCOR).     

Introduction of a phosphorus ylide moiety into [η-(ω-hydroxy)alkenyl]chromium(0) carbene complexes with Ph3PCCO and consecutive Wittig alkenations with 2-alkynals. Part 12: the chemistry of metallacyclic alkenylcarbene complexes

Ketenylidenetriphenylphosphorane, Ph₃PCCO (2), reacts selectively with the ω-hydroxy group of the alkene-carbene complexes (OC)₄CrC(η²-NMeCH₂CHCHCH₂OH)R¹ (1) (R¹=Me: (1a); Ph: (1b)) to give the acyl ylide terminated complexes (OC)₄CrC[(4,5-η²)-NMeCH₂CHCHCH₂O(O)C-CHPPh₃]R¹ (3) (R¹=Me: (3a); Ph: (3b)). Complexes 3 undergo Wittig alkenation reactions with aldehydes such as 2-alkynals, R²-CC-CHO (R²=H, SiMe₃, Ph), to give the corresponding 4Z, 9E-dien-11-ynes (OC)₄CrC[(4,5-η²)-NMeCH₂CHCHCH₂O(O)C-CHCH-CC-R²]R¹ (4-6) (R¹=Me, R²=H, SiMe₃, Ph: (4a-6a); R¹=Ph, R²=H, SiMe₃, Ph: (4b-6b)). All complexes were characterized in solution by one- and two-dimensional NMR spectroscopy (¹H, ¹³C, ²⁹Si, ³¹P, ¹H/¹H COSY, ¹³C/¹H HETCOR, ³¹P/³¹P EXSY).     

Synthesis of new α,α,β,β-tetrafluoroesters

Substituted phenyl iodides or diiodides reacted with ethyl iodotetrafluoroproponylate ICF₂CF₂CO₂Et, 1 in the presence of copper powder to give the coupled products 2 or 3 in good yields. Addition of 1 to ethylene and allyl acetate proceeded smoothly under thermal and radical conditions to give the corresponding adducts, which underwent elimination reaction to give β-vinyl and β-allyl α,α,β,β-tetrafluoroesters, CH₂CHCF₂CF₂CO₂Et, 4 and CH₂CHCH₂CF₂CF₂CO₂Et, 5, respectively. 1 also readily reacted with 1,5-hexadiene and 1-hexene with copper or palladium complex, followed by reduction to remove iodine to produce ω-alkenyl-α,α,β,β-tetrafluoroester CH₂CH(CH₂)₄CF₂CF₂CO₂Et 6 and α,α,β,β-tetrafluoroester C₄H₉CH₂CHICF₂CF₂CO₂Et.     

Self-immobilized metallocene catalysts bearing an allyl group for ethylene polymerization, X-ray crystal structure of [(CH2CHCH2)CH3Si(C13H8)2]ZrCl2

A series of ansa-metallocene complexes with an allyl substituted silane bridge [(CH₂CHCH₂)CH₃Si(C₅H₄)₂]TiCl₂ (1), [(CH₂CHCH₂)CH₃Si(C₉H₆)₂]MCl₂ [M=Ti (2), Zr (3), Hf (4)] and [(CH₂CHCH₂)CH₃Si(C₁₃H₈)₂]ZrCl₂ (6) have been synthesized and characterized. The molecular structure of 6 has been determined by X-ray crystallographic analysis. Complexes 1-4, 6 bearing allyl groups have been investigated as self-immobilized catalysts for ethylene polymerization in the presence of MMAO. The results showed that the self-immobilized catalysts 1-4, 6 kept high ethylene polymerization activities of ca. 10⁶ g PE mol⁻¹ M h⁻¹ and high molecular weight (M_w≈10⁵) of polyethylene.     

New aromatic pentafluoro-λ-sulfanyl (SF5) derivatives, m-SF5(CF2)2C6H4X: (X = N3, Br, OC(O)CHCH2, CHCH2)

Preparation of the following new m-SF₅CF₂CF₂C₆H₄X derivatives has been achieved: X=N₃(2), Br(3), OC(O)CHCH₂(4), CHCH₂(5). The compounds were characterized by their respective IR, NMR, mass spectra (MS) and high resolution mass spectrometry (HRMS). An improved yield of SF₅(CF₂)₂C₆H₅ (1) is also reported along with the synthesis of the polyacrylate (6) and polystyrene (7) from their respective monomers.     

The first N-alkyl-N′-polyfluorohetaryl sulfur diimide

The first AlkNSNHet_F sulfur diimide 6 (Alk=adamant-1-yl, Het_F=2,3,5,6-tetrafluoropyrid-4-yl) was prepared by trapping of the corresponding alkylthiazylamide [AlkNSN]⁻3 with pentafluoropyridine, followed by X-ray structural characterization. For 6, the Z,E configuration was found. From the reaction of 3 with octafluoronaphthalene, hexafluorinated naphthothiadiazole 7 was isolated along with the parent AlkNH₂.     

Stereochemistry of the insertion of disubstituted alkynes into the metal aminocarbyne bond in diiron complexes

Terminal alkynes (HCCR^′) (R^′=COOMe, CH₂OH) insert into the metal-carbyne bond of the diiron complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCMe)(Cp)₂][SO₃CF₃] (R=Xyl, 1a; CH₂Ph, 1b; Me, 1c; Xyl=2,6-Me₂C₆H₃), affording the corresponding μ-vinyliminium complexes [Fe₂{μ-σ:η³-C(R^′)CHCN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Xyl, R^′=COOMe, 2; R=CH₂Ph, R^′=COOMe, 3; R=Me, R^′=COOMe, 4; R=Xyl, R^′=CH₂OH, 5; R=Me, R^′=CH₂OH, 6). The insertion is regiospecific and C-C bond formation selectively occurs between the carbyne carbon and the CH moiety of the alkyne. Disubstituted alkynes (R^′CCR^′) also insert into the metal-carbyne bond leading to the formation of [Fe₂{μ-σ:η³-C(R^′)C(R^′)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R^′=Me, R=Xyl, 8; R^′=Et, R=Xyl, 9; R^′=COOMe, R=Xyl, 10; R^′=COOMe, R=CH₂Ph, 11; R^′=COOMe, R=Me, 12). Complexes 2, 3, 5, 8, 9 and 11, in which the iminium nitrogen is unsymmetrically substituted, give rise to E and/or Z isomers. When iminium substituents are Me and Xyl, the NMR and structural investigations (X-ray structure analysis of 2 and 8) indicate that complexes obtained from terminal alkynes preferentially adopt the E configuration, whereas those derived from internal alkynes are exclusively Z. In complexes 8 and 9, trans and cis isomers have been observed, by NMR spectroscopy, and the structures of trans-8 and cis-8 have been determined by X-ray diffraction studies. Trans to cis isomerization occurs upon heating in THF at reflux temperature. In contrast to the case of HCCR^′, the insertion of 2-hexyne is not regiospecific: both [Fe₂{μ-σ:η³-C(CH₂CH₂CH₃)C(Me)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Xyl, 13; R=Me, 15) and [Fe₂{μ-σ:η³-C(Me)C(CH₂CH₂CH₃)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Xyl, 14, R=Me, 16) are obtained and these compounds are present in solution as a mixture of cis and trans isomers, with predominance of the former.     

Preparation, characterization, and reactivities of thienyl nickel complexes bearing indenyl ligands

The complexes (1-R, 2-R′-indenyl)NiPPh₃(thienyl) (R′=H, R=Me (1); Et (2); i-Pr (3); CH₂Ph (4); R′=Ph, R=Me (5)) have been prepared and characterized by spectroscopic techniques and, in the case of 1, 2 and 5, by X-ray crystallographic studies. When combined with MAO, these compounds catalyze the polymerization of phenylacetylene to cis-transoidal poly(phenylacetylene) with M_w in the range of 5-7.5×10⁴ Da. NMR studies have revealed that MAO methylates these complexes without ionizing the Nithienyl bond; this implies that the polymerization reactions likely follow a non-cationic mechanism similar to that catalyzed by the corresponding NiCCPh complexes studied previously. Complexes 1-5 reacted with CF₃SO₃H to produce the corresponding NiOSO₂CF₃ compounds by protonation at the α-C of the thienyl moiety. The compound (1-Bzindenyl)Ni(PPh₃)(OSO₂CF₃) (9) has been isolated and fully characterized.     

A new method for the preparation of N-stabilized allenylidene complexes of chromium and tungsten

Displacement of tetrahydrofuran in [(CO)₅M(THF)] (M=Cr, W) by the anion [CCC(X)Y]⁻ (X=O; NR; Y=NR′₂, Ph) followed by alkylation of the resulting metalate with [R″₃O]BF₄ (R″=Me, Et) offers a convenient and versatile route to π-donor-substituted allenylidene complexes, [(CO)₅MCCC(XR″)Y]. Allenylidene complexes in which the terminal carbon atom of the allenylidene ligand constitutes part of a heterocycle are likewise accessible by this reaction sequence. Reaction of [(CO)₅M(THF)] with Li[CCC(NMe)Ph]⁻ and subsequent protonation of the metalate afford [(CO)₅MCCC(NMeH)Ph] in high yield. As indicated by the spectroscopic data of the compounds and the X-ray analyses of three representative examples, these allenylidene complexes are best described as hybrids of allenylidene and zwitterionic alkynyl complexes with delocalisation of the electron pair at nitrogen towards the metal center. Dimethylamine reacts with the amino(phenyl)allenylidene complex [(CO)₅CrCCC(NMe₂)Ph] (7a) by addition of the amine across the C_αC_β bond to give selectively the E-alkenyl(amino)carbene complex [(CO)₅CrC(NMe₂)CHC(NMe₂)Ph] (12). In contrast, the reaction of dimethylamine with the amino(methoxy)allenylidene complex [(CO)₅CrCCC(NMe₂)OMe] (1a) proceeds by addition of the amine to the C_γ atom and subsequent elimination of methanol to give the substitution product [(CO)₅CrCCC(NMe₂)₂] (13). Triphenylphosphane neither adds to the C_α nor the C_γ atom of 7a but upon irradiation displaces a CO ligand to form a cis-allenylidene(tetracarbonyl)phosphane complex 15.     

Synthesis and repellent properties of vinylidene fluoride-containing polyacrylates

Fluorinated polyacrylats with side group containing vinylidene fluoride (VDF) units (CF₃(CF₂)_n (CH₂CF₂)_m, n = 3, 5; m = 1, 2) were successfully synthesized. The water and oil repellency properties of these polymers are similar to those of fluorinated polyacrylate with side group containing long perfluorooctyl group (CF₃(CF₂)₇). The thermal telomerization of CF₃(CF₂)₅I and CF₃(CF₂)₃I with vinylidene fluoride (VDF) provided CF₃(CF₂)₅CH₂CF₂I (1b) and CF₃(CF₂)₃CH₂CF₂CH₂CF₂I (1c), respectively. The addition of 1b with ethylene followed by hydrolysis gave CF₃(CF₂)₅CH₂CF₂CH₂CH₂OH (2b). Treatment of 1c with ethyl vinyl ether in the presence of Na₂S₂O₄ followed by reduction produced CF₃(CF₂)₃CH₂CF₂CH₂CF₂CH₂CH₂OH (2c). Fluoroacrylates 3b-d were prepared by acrylation of the corresponding fluoroalcohols 2b-d. The semi-continuous process emulsion co-polymerization of 3a-d with octadecyl acrylate and 2-hydroxylethyl acrylate initiated by (NH₄)₂S₂O₈ in the presence of a mixture emulsifiers of polyoxyethylene(10)nonyl phenyl ether (TX-10) and sodium lauryl sulfate provided stable latexes 4a-d, respectively. The water and oil repellency properties of 4b (R_f: CF₃(CF₂)₅CH₂CF₂) and 4c (R_f: CF₃(CF₂)₃CH₂CF₂CH₂CF₂) containing vinylidene fluoride (VDF) units were similar to those of 4a (R_f: CF₃(CF₂)₇) containing long perfluoroalkyl group and much better than those of polymer 4d (R_f: CF₃(CF₂)₃) with short perfluoroalkyl chain. Thus, polyacrylates containing vinylidene fluoride units showed promising aspects as the alternatives to the currently used water and oil repellent agents with long perfluoroalkyl chains.     

Organodiiron(II)-complexes containing a long conjugated hydrazonato spacer. Synthesis, characterization, electrochemical and structural studies

Organometallic hydrazines of general formula [(η⁵-Cp)Fe(η⁶-p-RC₆H₄NHNH₂)]⁺PF₆⁻ (Cp=C₅H₅; R=H, (1)⁺PF₆⁻; Me, (2)⁺PF₆⁻; MeO, (3)⁺PF₆⁻; Cl, (4)⁺PF₆⁻) react with equimolar quantities of (E)-4-(2-ferrocenylvinyl)-benzaldehyde, (E)-[(η⁵-Cp)Fe(η⁵-C₅H₄)CHCHC₆H₄CHO], to afford stereoselectively, the new homodimetallic hydrazones formulated as (E)-[(η⁵-Cp)Fe(η⁶-p-RC₆H₄)NHNCHC₆H₄CHCH(η⁵-C₅H₄)Fe(η⁵-Cp)]⁺PF₆⁻ (R=H, (5)⁺PF₆⁻; Me, (6)⁺PF₆⁻; MeO, (7)⁺PF₆⁻; Cl, (8)⁺PF₆⁻). These compounds were fully characterized by elemental analysis and spectroscopic techniques (¹H- and ¹³C-NMR, IR and UV-vis) and, in the case of complex (6)⁺PF₆⁻, by single crystal X-ray diffraction methods. The rotations of the ferrocenyl unit by 37.2° out of the NHNCHC₆H₄CHCH spacer and coordinated phenyl ring planes, may generate an unfavorable structure to allow π-electron delocalization along the entire hydrazonato backbone between the two metals separated through bonds by more than 1.8 nm, as confirmed by the electrochemical data.     

Synthesis of low molecular weight perfluoro oxymethylene vinyl ethers

Perfluoro oxymethylene vinyl ethers have been formed by a multi-step synthesis. The key intermediates are low molecular weight perfluoropolyether (PFPE) fluoroformates CF₃O(CF₂O)_nCOF (I) n=1-6 obtained from the photo-oxidation of perfluoro propene (HFP) in perfluorohexane. Under certain conditions the light-mediated fluorination of PFPE fluoroformates (I) gives PFPE hypofluorites CF₃O(CF₂O)_nCF₂OF (II), which can be added to sym dichlorodifluoroethene to form the dichloro adduct CF₃O(CF₂O)_nCF₂OCFClCF₂Cl (III) which, after dechlorination, gives the desired vinyl ethers CF₃O(CF₂O)_nCF₂OCFCF₂ (IV). Every reaction step has to be properly controlled as far as the reaction variables are concerned. A mechanistic scheme is presented that is consistent with the observed experimental data.     

Interaction of copper(II) and palladium(II) with linked 2,2′-dipyridylamine derivatives: Synthetic and structural studies

Interaction of copper(II) salts with 2,2′-dipyridylamine (1), N-cyclohexylmethyl-2,2′-dipyridylamine (2), di-2-pyridylaminomethylbenzene (3), 1,2-bis(di-2-pyridylaminomethyl)-benzene (4), 1,3-bis(di-2-pyridylaminomethyl)benzene (5), 1,4-bis(di-2-pyridylaminomethyl)benzene (6), 1,3,5-tris(di-2-pyridylaminomethyl)benzene (7) and 1,2,4,5-tetrakis(di-2-pyridylaminomethyl)benzene (8) has yielded the following complexes: [Cu(2)(μ-Cl)Cl]₂, [Cu(3)(μ-Cl)Cl]₂ · H₂O, [Cu₂(4)(NO₃)₄], [Cu₂(5)(NO₃)₄] · 2CH₃OH, [Cu₂(6)(CH₃OH)₂(NO₃)₄], [Cu₄(8)](NO₃)₄] · 4H₂O while complexation of palladium(II) with 1, 4, 5 and 6 gave [Pd(1)₂](PF₆)₂ · 2CH₃OH, [Pd₂(4)Cl₄], [Pd₂(4)(OAc)₄], [Pd₂(5)Cl₄], [Pd₂(6)Cl₄] and [Pd₂(6)(OAc)₄] · CH₂Cl₂, respectively. X-ray structures of [Cu(2)(μ-Cl)Cl]₂, [Cu(3)(μ-Cl)Cl]₂ · 2C₂H₅OH, [Cu₂(6)(CH₃OH)₂(NO₃)₄], [Pd(1)₂](PF₆)₂ · 2CH₃OH, [Pd₂(4)(OAc)₄] · 4H₂O and [Pd₂(6)(OAc)₄] · 2CH₂Cl₂ are reported. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a diverse range of coordination geometries and lattice arrangements, with the structures of [Pd₂(4)(OAc)₄] · 4H₂O and [Pd₂(6)(OAc)₄] · 2CH₂Cl₂, incorporating the isomeric ligands 4 and 6, showing some common features. Liquid–liquid (H₂O/CHCl₃) extraction experiments involving copper(II) and 1–3, 5, 7and 8 show that the degree of extraction depends markedly on the number of dpa-subunits (and concomitant lipophilicity) of the ligand employed with the tetrakis-dpa derivative 8 acting as the most efficient extractant of the six ligand systems investigated.     

Formation of keto-carbeniums from 1,2,2-triarylacenaphthen-1-ols by breaking a long CC bond: unusual alcohol protonolysis accompanied by formal hydride abstraction

Oxidation of 1,2,2-tris(4-dimethylaminophenyl)- and 2,2-bis(4-dimethylaminophenyl)-1-phenylacenaphthen-1-ols 1a,b with I₂ induced the C₁C₂ bond fission to give 8-aroylnaphthalen-1-yl-bis(4-dimethylaminophenyl)carbenium derivatives 2a,b⁺, the intramolecular Lewis acid-base pairs. Treatment of 1 with HBF₄ did not induce the expected COH bond heterolysis but caused fission of COH and C₁C₂ bonds to give exactly the same carbenium 2⁺.     

Synthesis, spectroscopic characterization and reactivities of linear and butterfly chromium/selenium complexes containing substituted cyclopentadienyl ligands: crystal structures of [{η-MeC5H4Cr(CO)2}2Se] and [{η-EtO2CC5H4Cr(CO)2}2Se2]

The Cr-Cr singly-bonded dimers [{η⁵-RC₅H₄Cr(CO)₃}₂] (1, R=Me; 2, R=CO₂Et) reacted with an equivalent of elemental selenium in THF at room temperature to give the linear Cr₂Se complexes [{η⁵-RC₅H₄Cr(CO)₂}₂Se] (3, R=Me; 4, R=CO₂Et), whereas the linear Cr₂Se complex (5, R=MeCO) reacted with excess NaBH₄, Ph₃PCHPh or 2,4-dinitrophenylhydrazine under respective conditions to afford the linear Cr₂Se derivatives [{η⁵-RC₅H₄Cr(CO)₂}₂Se] (6, R=MeCH(OH); 7, R=PhCHCMe; 8, R=2,4-(NO₂)₂C₆H₃NHNCMe). Similarly, while the butterfly Cr₂Se₂ complexes [{η⁵-RC₅H₄Cr(CO)₂}₂Se₂] (9, R=Me; 10, R=CO₂Et) could be produced either by reaction of dimers 1 and 2 with an excess amount of elemental selenium, or by reaction of the linear complexes 3 and 4 with an equivalent of elemental selenium, the butterfly Cr₂Se₂ derivatives [{η⁵-RC₅H₄Cr(CO)₂}₂Se₂] (12, R=MeCH(OH); 13, R=PhCHCMe; 14, R=2,4-(NO₂)₂C₆H₃NHNCMe) were yielded by reaction of the butterfly Cr₂Se₂ complex (11, R=MeCO) with an excess quantity of NaBH₄, Ph₃PCHPh and 2,4-dinitrophenylhyazine. Both the linear complexes 3, 4, 6-8 and the butterfly complexes 9, 10, 12-14 are new, which have been fully characterized by elemental analysis, spectroscopy and X-ray crystallography.     

Convenient syntheses of fluorous phenols of the formula HOC6H5−n((CH2)3(CF2)7CF3)n (n=1, 2) and the corresponding triarylphosphites

The aldehydic benzyl ethers PhCH₂OC₆H₄CHO (2; a/b = para/meta series) are readily available from the corresponding phenols and react with Wittig reagents derived from [Ph₃PCH₂CH₂R_f8]⁺I⁻ (R_f8=(CF₂)₇CF₃) to give PhCH₂OC₆H₄CHCHCH₂R_f8 (86-93%, Z major). Reactions with H₂ over Pd/C give the fluorous phenols HOC₆H₄(CH₂)₃R_f8(4a,b; 87-91%). Condensations with PCl₃ and NEt₃ (3.0:1.0:3.3 mol ratio) give the fluorous phosphites P[OC₆H₄(CH₂)₃R_f8]₃(5a,b; 92-94%), but traces of 4a,b are difficult to remove. The phthalate-based benzyl ethers PhCH₂OC₆H₃(COOR)₂ (7; ,5/3,4 OC₆H₃-3,n-(R)₂ series) are easily accessed and reduced with LiAlH₄ to the diols PhCH₂OC₆H₃(CH₂OH)₂(8c,d; 89-90%). Diol 8c and the Dess-Martin periodinane react to give the dialdehyde PhCH₂OC₆H₃(CHO)₂ (9c; 95%). This is elaborated by a sequence analogous to 2→4→5 to the fluorous phenol HOC₆H₃((CH₂)₃R_f8)₂ (11c; 97%/96%, two steps) and phosphite P[OC₆H₃((CH₂)₃R_f8)₂]₃ (12c, 92%), from which traces of 11c are difficult to remove. Diol 8d can be similarly elaborated to 11d, but the dialdehyde 9d is labile and the combined yield of the Dess-Martin/Wittig steps is 32%. The CF₃C₆F₁₁/toluene partition coefficients of 11c,d, and 12c (two pony tails; 70:30, 72:28, 92:8) are much higher than those of 4a and b (one pony tail; 12:88, 14:86).     

Metallacrown ethers: synthesis and structural investigation of silver metallamacrocycles

The bis-monodentate ligands 1 and 2 based on the interconnection of two pyrazolyl units by CH₂(CH₂OCH₂)_nCH₂ (n=3 or 4) spacers, respectively, lead to the formation of either mono nuclear silver metallamacrocycle 10 in the case of 1 or binuclear silver metallamacrocycle 11 in the case of 2. Both complexes have been characterised in the solid state by X-ray diffraction on single crystals.     

Reactions of 2,2-bis(trifluoromethyl)oxirane with alcohols under phase transfer catalysis

It was demonstrated that the reaction of 2,2-bis(trifluoromethyl)oxirane (1) with variety of alcohols could be successfully carried out under phase transfer catalysis conditions using sodium or potassium hydroxide as a base. For example, reaction of CH₃OH, C₂H₅OCH₂CH₂OH, HOCH₂CH₂OH with one or two moles of 1 in the presence of the catalyst [(C₄H₉)₄N⁺HSO₄⁻] gives the corresponding tertiary alcohols R[OCH₂C(CF₃)₂OH]_n (n=1 or 2) in 43-53% yield, along with some O[CH₂C(CF₃)₂OH]₂. Benzyl alcohol and phenol under similar conditions are less active, producing in the reaction with 1 the corresponding adducts ArOCH₂C(CF₃)₂OH in 31-35% yield. Fluorinated alcohols, such as CF₃CH₂OH, ClCF₂CH₂OH, HCF₂CF₂CH₂OH have much higher reactivity towards 1 giving ring opening products in 82-97% yield. Even in the reaction of hindered hexafluoro-iso-propanol the corresponding adduct was isolated in 43% yield. Surprisingly, the reaction of iso-propanol and epoxide 1, results in the formation of O[CH₂C(CF₃)₂OH]₂ as a major product, isolated in 56% yield. Possible mechanism for the formation of the last product was proposed.