Jaroslav Kvíčala

Preparation of bis(polyfluoroalkyl)cyclopentadienes, new highly fluorophilic ligands for fluorous biphase catalysis

Abstract Bis[2-(perfluoroalkyl)ethyl]cyclopentadienes were synthesized from lithium [2-(perfluoroalkyl)ethyl]cyclopentadienides and 2-(perfluoroalkyl)ethyl triflates as mixtures of four regioisomers, structure of which was determined by 1H and 13C NMR spectroscopy. 2-(Perfluoroalkyl)ethyl triflates are useful fluorinated building blocks that can be employed in the synthesis of functionalised polyfluorinated substances.

Synthesis, fluorophilicities and regioisomer composition of ferrocenes and rhodium complexes based on bis(polyfluoroalkylated) cyclopentadienes

Abstract Ferrocenes and rhodium(I) carbonyl complexes were synthesized from lithium bis[2-(perfluoroalkyl)ethyl]cyclopentadienides and ferrous chloride–THF complex or tetracarbonyldichlorodirhodium. Fluorophilicities of starting bis[2-(perfluoroalkyl)ethyl]cyclopentadienes and ferrocenes made there from were determined. Four regioisomers of bis[2-(perfluoroalkyl)ethyl]cyclopentadienes, three regioisomers of the corresponding ferrocenes and two regioisomers of the corresponding rhodium complexes were identified and their ratio determined by 1D and 2D NMR spectroscopy.

Methyl 3,3,3-trifluoropyruvate: an improved procedure starting from hexafluoropropene-1,2-oxide; identification of byproducts

Optimized laboratory-scale preparation of methyl 3,3,3-trifluoropyruvate (3, MTFP) has been developed starting from industrial hexafluoropropene-1,2-oxide (1, HFPO) via methyl 2,3,3,3-tetrafluoro-2-methoxypropanoate (2, MTPr), which was transformed to 3 using sulfuric acid with isolated yields up to 81%. Byproducts formed in the transformation of 2 to 3, viz. methyl trifluoroacetate (4, MTAc), methyl 3,3,3-trifluoropyruvate hydrate (5), methyl hemiacetal of trifluoropyruvate (6), a dimer of methyl 3,3,3-trifluoropyruvate hydrate (7, DimMTP), and methyl fluorosulfate (8, Sulf) were identified and their amounts determined under various experimental conditions. Potential reaction pathways leading to the formation of the byproducts are discussed.

Radical-induced reaction of monoiodo- and diiodo-perfluoroalkanes with allyl acetate: telomer and rearranged products, mass-spectral distinguishing of regioisomers

Abstract The radical reaction of monoiodoperfluoroalkanes R F I (R F = C 4 F 9 , C 6 F 13 , C 8 F 17 ) and diiodoperfluoroalkanes I-Q-I (Q = C 4 F 8 , C 6 F 12 ) with allyl acetate initiated by peroxidic initiators is described. Under the reaction conditions employed, the conversion of both R F I and IQI was complete in most cases. The reactions of R F I also yielded some 2:1 telomers which are new compounds which have been characterized. In certain cases, the telomers were isolated in preparative yield up to 34%. Both 1:1 adducts [R F CH 2 CHICH 2 OCOCH 3 , (2a-c) ] and 2:1 telomers (5a-c) underwent subsequent thermal rearrangement [formation of R F CH 2 CH(OCOCH 3 )CH 2 I, (3a-c) , and telomers (6a-c) , respectively] at elevated temperatures. In the reaction of diiodides IQI, monoadducts [CH 3 COOCH 2 CHICH 2 QI, (9a,b) ] and diadducts [(CH 3 COOCH 2 CHICH 2 ) 2 Q (10a,b)] were formed, but no telomeric and rearranged products were found under the reaction conditions employed. On the other hand, isolated mono- (9) and di-adducts (10) underwent a similar rearrangement to the compounds 2a-c and 5a-c at elevated temperatures. Regioisomeric primary and rearranged products could be distinguished by mass spectrometry in which characteristic signals for a series of compounds with different R F groups were found.

Radical additions to fluoro-olefins. Photochemical mono-fluoroalkylation and sequential bis-fluoroalkylation of oxolane

Oxolane was fluoroalkylated by its photoadditions under atmospheric pressure. Monofluoro-alkylations were carried out with hexafluoropropene (1) and perfluorovinyl ethers C,F,&[ CF( CF,)CF,O] .-CF=CF2 (2-4, n = O-2) by direct photoexcitation of the olefins to give high yields of addition products 9-12 (Sl-94%). The reactions were completely regioselective at the oxolane molecule and almost completely regioselective (93-99%) at the double bond of fluoro-oletins; no bis-fluoroalkylated oxolanes were detected. The completely selective

Low-temperature 19F NMR spectroscopy of 1-fluoro-1-lithioethenes: Stability, shifts and unexpected coupling constants

Abstract Half-lives and fluorine atom shifts of stabilized 1-fluoro-1-lithioethenes bearing hydrogen, fluorine, phenyl, and/or dimethylphenylsilyl groups in the β-positions have been determined by a low-temperature 19 F NMR spectroscopy. Some 1-fluoro-1-lithioethenes displayed an exceptionally low value of the trans - 3 J FF coupling constant. Stereoselectivity of carbenoid formation, as well as an effect of configuration on the stability is discussed.

Reactivity study of 1,1,2,4,4,5,7,7,8,8,9,9,9-tridecafluoro-5-trifluoromethyl-3,6-dioxanon-1-ene in nucleophilic reactions: fluorination properties of secondary amine adducts

Abstract A series of nucleophiles was reacted with 1,1,2,4,4,5,7,7,8,8,9,9,9-tridecafluoro-5-trifluoromethyl-3,6-dioxanon-1-ene ( 1 ) as a representative of perfluoro(alkyl vinyl ethers). All reactions were completely regioselective with the nucleophilic attack at the terminal carbon atom. Reactions of hydroxy compounds, thiols and sec-amines afforded addition products, but butyllithium, tributylphosphane or complex hydrides caused displacement of vinylic fluorine: butyllithium afforded cis -derivative, while reactions with hydrides and the phosphane led to mixtures of cis - and trans -derivatives. Diethylamine and piperidine adducts displayed the property to substitute hydroxyl for fluorine in hexadecan-1-ol. Molecular properties of hexafluoropropene and perfluoro(methyl vinyl ether) were calculated by ab initio method at the MP2/6-311G(d,p) level of theory and their impact on relative reactivity was estimated.

Ionic telomerization of chlorofluoropropionyl fluorides with hexafluoropropene oxide

Abstract Six chlorofluoropropionyl fluorides were synthesized by converting a −CCl 3 group in perhalogenated chlorofluoropropanes to a −COF group in two reaction steps. The ionic telomerization of the acyl fluorides with hexafluoropropene oxide, catalyzed by fluoride ion, afforded mainly a mixture of 1:1 to 1:3 telomers. In some cases, substitution of chlorine for fluorine in the acyl moiety and hexafluoropropene oxide oligomerization occurred as side reactions. The effect of the number of chlorines in the starting acyl fluoride on the telomer distributions and by product formation is discussed. The reactivity order of the acyl fluorides YCOF in the telomerization reaction was: CF 3 CClF ( 2a ), CClF 2 CF 2 ( 2b ) > CF 3 CCl 2 ( 3a ), CClF 2 CClF ( 3b ) > CClF 2 CCl 2 ( 4a ), CCl 2 FCClF ( 4b ). Possible reaction pathways are discussed.

The chemo-selective reduction of fluorinated halogenoesters with sodium borohydride. Fluorinated halogenoalkanols and their (meth)acrylates

Abstract Several chlorofluoroalkanols R F -CH 2 OH (R F is CF 3 -CFCl, CF 2 Cl-CF 2 , CF 2 Cl-CFCl and CF 2 Cl) and their methacrylates or acrylates were synthesized. The corresponding polymeric methacrylates have properties of highly-sensitive electron-beam and X-ray resists for microlithograhy. The main step in the syntheses, which start from halogenoalkanes R F -CCl 3 , is the chemo-selective reduction of halogenoesters with sodium borohydride, in which the C-Cl bonds in the acyl parts of the esters are not attacked. Relative rates of the reductions of esters R F -COOCH 3 are influenced by the structure of halogenoalkyls R F in the order CF 2 Cl : CF 3 -CFCl CF 2 CL-CFCl = 4.5: : 3.5 : 1 . A remarkable reactivity decrease in the reduction rate in the structure possessing a Cl atom at the β-position in the acyl group is discussed.

Preparation and 13C NMR spectroscopy of 13C-1 labelled 2,2-diaryl-1-fluoro-1-lithioalkenes

Abstract Two 13 C-1 labelled 2,2-diaryl 1-fluoro-1-lithioalkenes have been synthesised. and the first 13 C NMR spectra of fluorocarbenoids have been obtained.