(Me3Si)3SiH-mediated intermolecular radical perfluoroalkylation reactions of olefins in water

Article abstract of DOI:10.1021/jo100901z

Figure presented. Perfluoroalkyl-substituted compounds are regarded as important components of fluorophors and for the introduction of fluorous tags into organic substrates. Their syntheses in organic solvents are achieved through different methods, among which, the addition of perfluoroalkyl radicals to unsaturated bonds represents a convenient choice. On the other hand, intermolecular radical reactions in water have attracted the attention of synthetic chemists as a strategic route to carbon-carbon bond formation reactions. In this paper we undertook the intermolecular addition of perfluoroalkyl radicals on electron rich alkenes and alkenes with electron withdrawing groups in water, mediated by silyl radicals, and obtained perfluoroalkyl-substituted compounds in fairly good yields. The radical triggering events employed consist of the thermal decomposition of an azo compound and the dioxygen initiation. Our results indicate that for intermolecular carbon-carbon bond formation reactions mediated by (Me ₃Si)₃SiH, the decomposition of the azo compound 1,1′-azobis(cyclohexanecarbonitrile) (ACCN) is the best radical initiator. We also found that water exerts a relevant solvent effect on the rates of perfluoroalkyl radical additions onto double bonds and the H atom abstraction from the silane. Our account provides a versatile and convenient method to achieve perfluoroalkylation reactions of alkenes in water to render perfluoroalkylated alkanes as key intermediates in the synthesis of fluorophors and other fluorinated materials. This is the first report where perfluoroalkyl-substituted alkanes are synthesized through intermolecular radical carbon-carbon bond formation reactions in water, mediated by silyl radicals.

Full text of DOI:10.1021/jo100901z

pubs.acs.org/joc
(Me3Si)3SiH-Mediated Intermolecular Radical Perfluoroalkylation
Reactions of Olefins in Water
‡
Sebastian Barata-Vallejo and Al Postigo*
,†
ꢀ
†Faculty of Science, University of Belgrano, Villanueva 1324 CP 1426-Buenos Aires, Argentina, and
‡
´
Departamento de Quımica Organica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos
ꢀ
ꢀ
Aires, Ciudad Universitaria, Pabellon 2, 3er piso, CP 1428-Buenos Aires, Argentina
alberto.postigo@ub.edu.ar
Received May 7, 2010
Perfluoroalkyl-substituted compounds are regarded as important components of fluorophors and
for the introduction of fluorous tags into organic substrates. Their syntheses in organic solvents are
achieved through different methods, among which, the addition of perfluoroalkyl radicals to
unsaturated bonds represents a convenient choice. On the other hand, intermolecular radical
reactions in water have attracted the attention of synthetic chemists as a strategic route to carbon-
carbon bond formation reactions. In this paper we undertook the intermolecular addition of
perfluoroalkyl radicals on electron rich alkenes and alkenes with electron withdrawing groups in
water, mediated by silyl radicals, and obtained perfluoroalkyl-substituted compounds in fairly good
yields. The radical triggering events employed consist of the thermal decomposition of an azo
compound and the dioxygen initiation. Our results indicate that for intermolecular carbon-carbon
bond formation reactions mediated by (Me3Si)3SiH, the decomposition of the azo compound 1,10-
azobis(cyclohexanecarbonitrile) (ACCN) is the best radical initiator. We also found that water exerts
a relevant solvent effect on the rates of perfluoroalkyl radical additions onto double bonds and the H
atom abstraction from the silane. Our account provides a versatile and convenient method to achieve
perfluoroalkylation reactions of alkenes in water to render perfluoroalkylated alkanes as key
intermediates in the synthesis of fluorophors and other fluorinated materials. This is the first report
where perfluoroalkyl-substituted alkanes are synthesized through intermolecular radical carbon-
carbon bond formation reactions in water, mediated by silyl radicals.
1. Introduction
different fields of chemistry. In particular, recent advance
in fluorous1 combinatorial technique requires convenient meth-
ods for selective introduction of fluorous tags containing
perfluoroalkyl groups2 into various organic compounds.3
The synthesis of these compounds cannot be achieved
through classical nucleophilic substitutions on perfluoroalkyl
halides, RfX, as these substrates are impeded to react by the
Perfluoroalkyl compounds have attracted much attention
during the past twenty years for their wide applications in
*To whom correspondence should be addressed. Phone/fax: þ54 11 4511-
4700.
(1) (a) Zhang, W. Tetrahedron 2003, 59, 4475–4489. (b) Curran, D. P.
Pharm. News 2002, 9, 179–188. (c) Villard, A.-L.; Warrington, B. H.;
Ladlow, M. J. Comb. Chem. 2004, 6, 611–622. (d) Zhang, W.; Luo, Z.; Chen,
C. H.-T.; Curran, D. P. J. Am. Chem. Soc. 2002, 124, 10443–10450.
(e) Lindsley, C. W.; Zhao, Z.; Newton, R. C.; Leister, W. H.; Strauss,
K. A. Tetrahedron Lett. 2002, 43, 4467–4470. (f) Lindsley, C. W.; Zhao, Z.;
Leister, W. H.; Strauss, K. A. Tetrahedron Lett. 2002, 43, 6319–6323.
(2) Gladysz, J. A.; Emnet, C.; Rabai, J. In The Handbook of Fluorous
Chemistry; Gladysz, J. A., Curran, D. P., Horvath, I. T., Eds.; Wiley-VCH:
Weinheim, Germany, 2004; pp 56-112.
(3) Park, G.; Ko, K.-S.; Zakharova, A.; Pohl, N. L. J. Fluorine Chem.
2008, 129, 978–982.
DOI: 10.1021/jo100901z
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Published on Web 08/25/2010
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Barata-Vallejo and Postigo
JOCArticle
SN1 mechanism, on account of the low stability of carboca-
tions, and precluded to undergo SN2 substitutions due to
repulsion of the lone electron pairs of the fluorine atoms to
the backside attack by the nucleophile.4
Compounds bearing the perfluoroalkyl moiety Rf-C
bond, however, have been synthesized by different routes.
One such route involves addition of Rf• radicals to double
bonds.5-7 Perfluoroalkyl iodides and bromides are conve-
nient perfluoroalkyl radical precursors in the presence of
radical initiators.8
molecular carbon-carbon bond formation deals with tris-
(trimethylsilyl)silane, (Me3Si)3SiH, in organic solvents.13
The need to resort to more environmentally friendly
solvents opened the scope of radical carbon-carbon bond
formation reactions in water, and other aqueous mixtures.
Atom transfer intermolecular carbon-carbon bond forma-
tion reactions in water have been investigated in detail by
many authors.14 Oshima et al.14a reported the intermolecular
carbon-carbon bond formation reaction in water from ethyl
bromoacetate and 1-octene affording ethyl 4-bromodecano-
ate in 80% yield when the reaction is initiated by triethylbo-
rane (BEt3)/air (eq 1).
Because perfluoroalkyl iodides exhibit their absorption in
UV and near-UV regions, the photoinitiation based on the
homolytic dissociation of the Rf-I bond is also applicable
for the iodoperfluoroalkylation of unsaturated compounds
with RfI.9 Ogawa et al. undertook an iodoperfluoroalkyla-
tion of unsaturated carbon-carbon double and triple bonds
in benzotrifluoride as solvent.4,9 These authors also utilized
nonconjugated dienes, conjugated dienes, allenes, vinylcyclo-
propanes, and isocyanides as radical-acceptor substrates
for the radical iodoperfluoroalkylation reactions in benzo-
trifluoride, affording good yields of the corresponding iodo-
perfluoroalkylated derivatives.
Another route to the synthesis of compounds with per-
fluoroalkyl moieties is through the SRN1 mechanism, which
involves radicals and radical ions as intermediates.4,10
On the other hand, intermolecular radical carbon-carbon
bond formation reactions, i.e., consecutive reactions, de-
mand a careful synthetic design to achieve carbon-carbon
coupling products in fairly good yields. The key step in these
consecutive reactions generally involves the intermolecular
addition of R• radicals to a multiple-bonded carbon accep-
tor. When a hydride chain carrier is involved care has to be
exercised in order to ensure that the effective rate of the
radical addition is higher than the rate of H atom transfer.
When silicon-centered radicals are used,11 for an efficient
chain process it is important that (i) the R03Si• radical reacts
faster with RZ (the precursor of radical R•) than with the
alkene, and (ii) that the alkyl radical reacts faster with the
alkene (to form the adduct radical) than with the silicon
hydride. This process has in due course been termed “dis-
ciplined intermediates”.12 The hydrogen donation step con-
trols the radical sequence and the concentration of silicon
hydride often serves as the variable by which the product
distribution can be influenced. The majority of sequential
radical reactions using silanes as mediators for the inter-
Other radical precursors such as bromomalonate and
bromoacetonitrile give excellent results of bromine atom
transfer products in water. A tandem radical addition-
oxidation sequence in water that converts alkenyl silanes
into ketones has been elegantly described by Oshima et al.15
Other types of intermolecular radical carbon-carbon bond
formation reactions in water have been reported lately,
describing radical additions to radical acceptors such as
imines and their derivatives.16-18 These latter consecutive
radical reactions are also initiated by BEt3/air.
The dioxygen radical initiation has recently been success-
fully applied in water for the hydrosilylation of alkynes
employing (Me3Si)3SiH/oxygen, rendering high yields of
the respective hydrosilylated alkene products with excellent
Z stereoselectivity.19
We have attempted several radical reactions in water
mediated by silyl radicals, among them, reduction of organic
halides,20 reduction of azides,21 hydrosilylation reactions
of multiple-bonded substrates,22 intramolecular carbon-
carbon bond formation reactions,23 etc., either by azo com-
pounds decomposition, photochemically or through dioxygen
initiation.
Dolbier et al.24 have found that perfluorinated radicals
were much more reactive than their hydrocarbon counter-
parts in addition to normal, electron rich alkenes such as
(13) Chatgilialoglu, C. Organosilanes in Radical Chemistry; John Wiley &
Sons, Ltd.: Chichester, UK, 2004; pp 143-184.
(14) (a) Yorimitsu, H.; Shinokubo, H.; Matsubara, S.; Oshima, K. J. Org.
Chem. 2001, 66, 7776–7785. (b) Miyabe, H.; Fujii, K.; Goto, T.; Naito, T.
Org. Lett. 2000, 2, 4071–4074.
(4) Vaillard, S.; Postigo, A.; Rossi, R. A. Organometallics 2004, 23, 3003–
3007.
(5) Bravo, A.; Bjorvski, H.-R.; Fontana, F.; Liguori, L.; Mele, A.;
Minischi, F. J. Org. Chem. 1997, 62, 7128–7136.
(15) Kondo, J.; Shinokubo, H.; Oshima, K. Angew. Chem., Int. Ed. 2003,
42, 825–827.
(6) Brace, N. O. J. Fluorine Chem. 2001, 108, 147–175. Brace, N. O.
J. Fluorine Chem. 1999, 93, 1–25. Brace, N. O. J. Fluorine Chem. 1999, 96,
101–127.
(7) Cahard, D.; Ma, J.-A. Chem. Rev. 2006, 104, 6119–6146.
(8) Baasner, B.; Hagemann, H.; Tatlow, J. C. Houben-Weyl Organo-
Fluorine Compounds; Thieme: Stuttgart, Germany, 2000; pp 1-56.
(9) Tsuchii, K.; Imura, M.; Kamada, N.; Hirao, T.; Ogawa, A.
J. Organomet. Chem. 2004, 69, 6658–6665.
(16) Miyabe, H.; Ueda, M.; Naito, T. J. Org. Chem. 2000, 65, 5043–5047.
(17) McNabb, S. B.; Ueda, M.; Naito, T. Org. Lett. 2004, 6, 1911–1914.
(18) Miyabe, H.; Yamaoka, Y.; Takemoto, Y. J. Org. Chem. 2005, 70,
3324–3327.
(19) Postigo, A.; Sbarbati Nudelman, N. Different Radical Initiation
Techiques of Hydrosilylation Reactions of Multiple Bonds in Water. Dioxy-
gen Initiation. J. Phys. Org. Chem. DOI: 10.1002/poc.1703. Published
Online: June 18, 2010.
(10) (a) Rossi, R. A.; Postigo, A. Curr. Org. Chem. 2003, 7, 747–769.
~ ~
(b) Rossi, R. A.; Pierini, A. B.; Pennenory, A. B. Chem. Rev. 2003, 103, 71–
168.
(11) Postigo, A. Photochemical Generation of Silicon-centered Radicals
and their Reactions. In Progress in Photochemistry; Nova Science Publica-
tions: Hauppauge, NY, 2008; Chapter VI, pp 193-226. ISBN 978-1-60456-
568-3..
(12) Barton, D. H. R. Half a Century of Free Radical Chemistry;
Cambridge University Press: Cambridge, UK, 1993.
(20) Postigo, A.; Ferreri, C.; Navacchia, M. L.; Chatgilialoglu, C. Synlett
2005, 2854–2856.
(21) Postigo, A.; Kopsov, S.; Ferreri, C.; Chatgilialoglu, C. Org. Lett.
2007, 9, 5159–5162.
(22) Postigo, A.; Kopsov, S.; Zlotsky, S.; Ferreri, C.; Chatgilialoglu, C.
Organometallics 2009, 28, 3282–3287.
(23) Postigo, A. Curr. Org. Chem. 2009, 13, 1683–1704.
(24) Rong, X. X.; Pan., H.-Q.; Dolbier, W. R., Jr. J. Am. Chem. Soc.
1994, 116, 4521–4522.
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SCHEME 1. Intermolecular Radical Carbon-Carbon Bond
SCHEME 2. Intermolecular Radical Carbon-Carbon Bond
Formation in Watera
Formation in Watera
aReactions of 1-hexene with haloperfluoroalkanes in water, initiated by
(Me3Si)3SiH/dioxygen.
aReactions of different alkenes with n-1-iodoperfluorohexane initiated
by (Me3Si)3SiH/dioxygen.
3a25b in 71% and 74% yields (isolated yields), respectively
(Scheme 1).
1-hexene (40 000 times more reactive) in organic solvents,
and that H transfer from (Me3Si)3SiH to a perfluoro-n-alkyl
radical such as n-C7F15CH2CH•C4H9 was 110 times more
rapid than that to the analogous hydrocarbon radicals (eq 2).
Styrene and p-methylstyrene when reacted with n-C6F13I
in water under (Me3Si)3SiH/dioxygen initiation give prod-
ucts 4a26 and 5a27 in 54% and 63% yields, respectively
(Scheme 1). In these latter cases, reduction of the iodo
compound (i.e., 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohex-
ane, CHF2(CF2)4CF3) was concomitantly obtained, as de-
1
termined from the H and 19F NMR spectra of the crude
reaction mixtures (centered triplet at 6.29 ppm, J = 22 Hz,
from terminal HCF2, in the 1H NMR spectrum and from the
19F NMR spectrum, the CF2H peak at δ = -114.05 ppm).
Alkenes with electron withdrawing groups such acryloni-
trile, crotonaldehyde, methyl acrylate, and vinyl methyl
ketone also react with n-C6F13I under the same radical
conditions, to afford the respective perfluoroalkylated prod-
ucts 6a,28,25c 7a, 8a, and 9a28,29 in yields ranging from 60%
to 77% (Scheme 1). The products are isolated from the crude
reaction mixture by extraction of the water phase with
pentane (3ꢀ), drying of the pentane layers with anhydrous
sodium sulfate, and filtering, and the evaporated pentane
extracts are reduced-pressure distilled.
It should be pointed out that a small minor byproduct (ca.
5%) detected from the oxygen-initiated reactions in water
corresponds to a compound observed by mass spectrometry
of mass 280 and formula minima C9H28Si4O2 whose struc-
ture has been assigned to (Me3SiO)2Si(H)SiMe3, arising
from the autoxidation of silane.30 This byproduct was con-
firmed by GC-co-injection with an authentic sample that has
been synthesized according to a reported procedure.30
Encouraged by the above results obtained from reactions
in water with n-C6F13I and different alkenes initiated by
(Me3Si)3SiH/dioxygen, we proceeded with the perfluoroalkyl-
ation reactions of electron rich 1-hexene with an array of
perfluoroalkyl halides (iodides and bromides) under the
same radical conditions in water.
Thus the authors determined that kadd (eq 2) has a value of
7.9 ꢀ 106 M-1 s-1 in benzene-d6 at 298 K, and the value of kH
is ca. 50 ꢀ 106 M-1 s-1 in benzene-d6 at 303 K.
Given the known rate acceleration effects of radical reac-
tions in water,23 it becomes challenging at this time to attempt
intermolecular carbon-carbon bond formation radical reac-
tions in this medium, mediated by silyl radicals. Therefore,
we herein embark on a study of the perfluoroalkylation of
electron rich alkenes and alkenes with electron withdrawing
groups, to explore the scope and limitations of the inter-
molecular addition reactions of perfluoroalkylated radicals
on alkenes in water mediated by (Me3Si)3SiH. The initiators
to be employed are azo compounds and dioxygen which up to
now gave us the best results in previous studies.18-21
Moreover, the scope of this paper is on the syntheses of
perfluoroalkyl-substituted alkanes, which are currently em-
ployed in fluorous syntheses. Our results are meant to
contribute with a versatile methodology for the synthesis
of perfluoroalkyl-substituted compounds in water.
2. Results and Discussion
When 1-hexene reacts with n-1-iodoperfluorobutane,
n-C4F9I, under the reaction conditions described above,
1,1,1,2,2,3,3,4,4-nonafluorodecane 1b31 is obtained in 88%
When 1-hexene is allowed to react with n-1-iodopefluoro-
hexane, n-C6F13I, in water, initiated by (Me3Si)3SiH/dioxygen
(see the Experimental Section), 1,1,1,2,2,3,3,4,4,5,5,6,6-
tridecafluorododecane 1a25a is obtained in 65% yield (Scheme 1).
Analogously, 1-octene and 1-decene afford, upon reaction with
n-C6F13I under the same radical conditions, products 2a25band
(26) Yang, G.-S.; Xie, X.-J.; Zhao, G.; Ding, Y. J. Fluorine Chem. 1999,
98, 159–161.
(27) Chen, W.; Xu, L.; Xiao, J. Tetrahedron Lett. 2001, 42, 4275–4278.
(28) Hu, C.-M.; Qiu, Y.-L. J. Org. Chem. 1992, 57, 3339–3342.
(29) Kyoko, N.; Oshima, K.; Utimoto, K. Bull. Chem. Soc. Jpn. 1991, 64,
403–409.
(25) (a) Davis, C. R.; Burton, D. J.; Yang, Z.-Yu J. Fluorine Chem. 1995,
70, 135–140. (b) Le, T. D.; Arlauskas, R. A.; Weers, J. G. J. Fluorine Chem.
1996, 78, 155–163. (c) Huang, X.-T.; Chen, Q.-Y. J. Org. Chem. 2001, 66,
4651–4656.
(30) Kopping, B.; Chatgililaloglu, C.; Zehnder, M.; Giese, B. J. Org.
Chem. 1992, 57, 3994–4000.
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SCHEME 3. Intermolecular Radical Carbon-Carbon Bond Formation in Watera
aReactions of alkenes with n-1-bromoperfluoroalkanes (CnF2nþ1Br, n = 6, 8, and 10) in water, Initiated by (Me3Si)3SiH/ACCN.
yield (Scheme 2). The reaction of 1-hexene with 1,4-diiodo-
1,1,2,2,3,3,4,4-octafluorobutane, n-IC4F8I, affords 1,1,2,2,-
3,3,4,4-octafluoro-1-iododecane 1c, obtained in 75% yield
(Scheme 2), and 15% of reduced 1,1,2,2,3,3,4,4-octafluor-
odecane, as observed from the 19F NMR spectrum, with the
CF2H peak at δ = -114.15 ppm.
When n-1-bromoperfluorohexane, n-C6F13Br, is allowed
to react with 1-hexene, product 1a25a is obtained in poor yield
(21%, Scheme 2, cf. with the same reaction carried out with
n-C6F13I, Scheme 1). Analogously, the reaction of 1-hexene
with n-1-bromoperfluorooctane, n-C8F17Br, progresses poorly
to give product 1d25b in 14% yield, while the same reaction
employing n-C8F17I affords 1d25b in 72% yield (Scheme 2).
In the same fashion, n-1-iodoperfluorodecane, n-C10F21I,
reacts with 1-hexene to afford 1e25b in 70% yield (Scheme 2),
but with n-C10F21Br, product 1e25b is obtained in 9% yield.
This could be in agreement with a stronger BDE of the bond
Rf-Br than that of Rf-I.
To cast some light into the efficiency of the chain reaction
with dioxygen, and see whether the low yields obtained from
1-hexene and RfBr and (Me3Si)3SiH/dioxygen are due either
to a slow initiation step or the retardation in the propagation
step on account of the different BDE of bromo- and iodo-
perfluoroalkanes, we undertook the radical chain initiation
with the azo compound ACCN, at 70 °C in water (see the
Experimental Section).
When a series of alkenes are allowed to react with bromoper-
fluoroalkanes (n-1-bromoperfluorohexane, n-1-bromoperfluoro-
octane, and n-1-bromoperfluorodecane) in water as described
for the thermal radical initiation reaction (see the Experimental
Section), the respective perfluoroalkylated products are ob-
tained in yields ranging from 50% to 77% (Scheme 3).
Thus, 1-hexene reacts with n-C6F13Br, n-C8F17Br, and
n-C10F21Br to afford the corresponding perfluoroalkylated
hexanes 1a,25a 1d,25b and 1e25b in 75%, 70%, and 62% yields,
respectively (Scheme 3). 1-Octene and 1-decene also afford
perfluoroalkylated alkanes in fairly good yields (50-77%).
Styrene and 4-methylstyrene react with n-C6F13Br, n-C8F17Br,
and n-C10F21Br to afford the alkylated products in good yields,
ranging from 46% to 81% (Scheme 3).
propiononitriles 6a,28 6d,32 and 6e28 in 51%, 50%, and 44%
yields, respectively. Crotonaldehyde, upon reaction with
n-C6F13Br, n-C8F17Br, and n-C10F21Br under the reaction
conditions described above, gives the perfluoroalkylated-
substituted butyraldehydes 7a, 7d, and 7e in 62%, 60%,
and 55% yields, respectively (Scheme 3).
Methyl acrylate upon reaction with the series CnF2nþ1Br
(n = 6, 8, and 10) affords the perfluoroalkylated-substituted
methyl propionates 8a, 8d,33 and 8e in 55%, 53%, and 43%
yields, respectively (Scheme 3), while vinyl methyl ketone
when reacted with n-C6F13Br, n-C8F17Br, and n-C10F21Br in
water under ACCN/(Me3Si)3SiH thermal initiation affords
the 5-perfluoroalkylated-substituted 2-butanones 9a,28,29
9d,34,28 and 9e34,28 in 67%, 70%, and 66% yields, respectively
(Scheme 3).
We also undertook the ACCN-radical initiated perfluoro-
alkylation of 1-hexene with CnH2nþ1I (n = 8, and 10), and
obtained compounds 1d25b and 1e,25b respectively, in yields
ranging from 90% to 95%, while the same yields under
dioxygen-radical initiation were in the 70% range (cf. O2-
initiated radical yields of 1d and 1e from Scheme 2).
These sets of experiments would reveal that the lower
yields obtained with the bromoperfluoroalkanes and alkenes
in water under dioxygen initiation than those obtained under
ACCN initiation could be attributed to a slower initiation in
the former rather than a retardation in the propagation step
due to differences in BDE of Rf-I and Rf-Br bonds;
however, some involvement of the BDE of Rf-I versus
Rf-Br should also be considered.
Given the optimal yields obtained from the radical reac-
tions of 1-bromoperfluoroalkanes and alkenes in water
initiated by (Me3Si)3SiH/ACCN, we undertook the reac-
tions depicted in Scheme 1 (n-C6F13I and different alkenes)
this time under ACCN initiation. Table 1 summarizes the
reaction yields of perfluoroalkyl-substituted compounds
1a-9a obtained from n-C6F13I, an array of alkenes, and
(Me3Si)3SiH/ACCN initiator.
It is observed that the yields of products 1a-9a are much
better under ACCN initiation (Table 1) than under dioxygen
initiation (Scheme 1)
Acrylonitrile, upon reaction with the series CnF2nþ1Br
(n = 6, 8, and 10) affords the perfluoroalkylated-substituted
(33) Sturz, G.; Clement, J. C.; Daniel, A.; Molinier, J.; Lenzi, M. Bull.
Soc. Chim. Fr. 1981, 1, 161–165.
(31) Delest, B.; Shtarev, A. B.; Dolbier, W. R. Tetrahedron 1998, 54,
9273–9280.
(32) Briza, T.; Kvicala, J.; Paleta, O.; Cermak, J. Tetrahedron 2002, 58,
3841–3846.
(34) (a) Umemoto, T.; Kuriu, Y.; Nakayama, S-i. Tetrahedron Lett. 1982,
23, 1169–1172. (b) Umemoto, T.; Gotoh, Y. Bull. Chem. Soc. Jpn. 1986, 59,
439–445. (c) Hamza, M’H. A.; Serratrice, G.; Stebe, M.-J.; Delpuech, J.-J.
J. Magn. Reson. 1981, 42, 227–231.
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TABLE 1. Intermolecular Radical Carbon-Carbon Bond Reactions in Water: Reactions of Different Alkenes (20-25 mM) with n-C6F13I (10 mM),
Initiated by (Me3Si)3SiH (5 mM)/ACCN (3 mM):
aIsolated yield after purification. bObtained in a 81:19 cis:trans ratio measured by 1H NMR
We also subjected electron-rich diallyl ether (3-(allyloxy)-
prop-1-ene) to the radical perfluoroalkylation reaction in
water with n-C6F13I (ACCN-initiation) and obtained the
perfluoroalkylated tetrahydrofuran derivative 10a25c in 68%
yield, in a cis:trans ratio of ca. 80:20 (Table 1, entry 10). Exo-
cyclization of the 6-hexenyl radical is a useful probe for the
elucidation of the radical mechanism of the reaction in water,
as has been observed for the cyclization of a 1-allyloxy-2-
iodobenzene derivative in water as well.21,25a
It can be deduced that all water-insoluble material (sub-
strates and reagents) suspended in the aqueous medium can
interact due to the vigorous stirring that creates an efficient
vortex and dispersion. In the dioxygen initiation, the chain
mechanism probably benefits from the enhanced contact sur-
face of tiny drops containing (Me3Si)3SiH and dioxygen.
It is worth mentioning that under our experimental pro-
cedure, initiation with oxygen does not take place under O2-
purging of the solution, nor with slow, continuous bubbling
of O2 or air. Oxygen or air introduced slowly by syringe-
pump techniques resulted in a less efficient initiation of the
chain radical reaction. Probably, the slow oxygen addition
into the solution with the balloon technique described above
allows for sufficient oxygen to be dissolved in the water
environment, thus initiating the radical chain (the solubility
of oxygen in water is 1.34 ꢀ 10-3 M at 22 °C; taking into
account that the substrate and (Me3Si)3SiH concentrations
are ca. 10 times higher, limiting working initiator concentra-
tions could be reached by the methodology).
The mechanism of the (Me3Si)3SiH-mediated intermolecular
perfluoroalkylation of alkenes in water is depicted in Scheme 4.
The (Me3Si)3Si• radical (produced either by dioxygen or
thermal decomposition of ACCN initiator) in water ab-
stracts the halogen atom (iodine or bromine) from RfX. This
Rf• radical reacts faster with the alkene than with the silicon
hydride, affording the perfluoroalkylated radical adduct 10.
The perfluoroalkylated radical adduct 10 abstracts hydrogen
from the silane, affording the perfluoroalkyl-substituted
alkane 11, and regenerating the silyl radical, thus propagat-
ing the chain.
According to what has been observed and measured by
Dolbier et al.,24 in benzene-d6, the ratio of products [3]/[2]
(eq 2) should equal the ratio of rate constants for addition
J. Org. Chem. Vol. 75, No. 18, 2010 6145

Barata-Vallejo and Postigo
JOCArticle
SCHEME 4. Mechanism for Radical Carbon-Carbon Bond
Formation Reactions from Alkenes and Perfluoroalkyl Iodides
in Water, Mediated by (Me3Si)3SiH
(kH/kadd)acrylonitrile
, respectively. This seems to indicate that
the reactivities of electron rich and electron deficient alkenes
toward Rf• radicals in water level off.
The ratio of rates constants (kH/kadd 1-hexene obtained in
)
benzotrifluoride as solvent24 for the reaction of n-C7F15I and
1-hexene with (Me3Si)3SiH as the hydrogen donor (eq 2) is
6.32, while that same ratio of rate constants for the reaction
of n-C6F13I with 1-hexene in water is 1.55 (vide supra). The
unavailability of the rate constant for Rf• radical addition
onto double bonds in water makes comparisons difficult;
however, our results would seem to imply that the rate for
hydrogen donation from (Me3Si)3SiH to the Rf• radical
relative to the addition reaction is four times slower in water
than in benzotrifluoride as solvent (i.e., (kH/kadd)water
(kH/kadd benzotrifluoride = 0.25). Indeed, it is likely that water
/
)
does influence the H-transfer step from the silane to the
C-radical. This is well established and important for phenols;
however, for silanes this is not known. In the phenol series
H-bonding of the phenol with the solvent leads to a stabiliza-
tion and consequently to less efficient H-transfer.36 H-bond-
ing from the silane to water might have a similar effect, as
we report on slower H-transfer in water. It can also be hypo-
thesized that given the known hypervalency of silicon,
coordination of a water molecule can diminish the hydrogen
atom donation of the silicon hydride.
The intermolecular radical carbon-carbon bond forma-
tion reactions presented herein in water take advantage of
the halophilicity of silyl radicals toward iodine and bromine
atoms. In our case, the halogen atom transfer reaction from
12 toward the perfluoroalkylated radical adduct 10 (Scheme 4)
is slower than the hydrogen atom abstraction from the
(Me3Si)3SiH, thus providing the reduced perfluoroalkylated
product 11. As a support to the mechanism proposed
(Scheme 4), 2-iodo-1,1,1,3,3,3-hexamethyl-2-(trimethyl)-
trisilane (12, X = I, Scheme 4) was isolated and char-
acterized18 from the reaction mixtures described in Scheme 1.
In the same fashion, from reactions described in Scheme 3,
2-bromo-1,1,1,3,3,3-hexamethyl-2-(trimethyl)trisilane (12, X=
Br, Scheme 4) was detected by gas chromatography, isolated,
and compared with an authentic sample.
(of perfluorinated heptyl radical on 1-hexene) and rate
constant for H abstraction from (Me3Si)3SiH times the ratio
of concentrations of alkene and silane. According to our
experimental conditions, employing the equation in ref 37,
we would obtain a theoretical ratio of perfluoroalkylated
alkane over reduced perfluoroalkane of ca. 1.3, which is not
completely in agreement with the unobserved reduced per-
fluoroalkanes in our reaction systems (i.e., CHF2(CF2)4CF3,
when iodoperfluorohexane is employed).
The electrophilicity of Rf• radicals is the dominant factor
giving rise to their high reactivity. The stronger carbon-
carbon bond that forms when Rf• versus R• radicals add to an
alkene is a driving force for the radical addition (the greater
exothermicity of the Rf• radical addition is expected to lower
the activation energy).35 It has been observed, in organic
solvents, that the rates of addition of Rf• radicals onto
alkenes correlate with the alkene IP (which reflects the HOMO
energies).31 Indeed, the major transition state orbital interaction
for the addition of the highly electrophilic Rf• radical to an
alkene is that between the SOMO of the radical and the HOMO
of the alkene. Thus, the rates of Rf• radical addition to electron
deficient alkenes are slower than those to electron rich alkenes
(as observed in organic solvents). From our results, however, it
becomes apparent that in water the reactivity for both electron
rich and electron deficient alkenes toward Rf• radical addition
could be comparable (cf. in Scheme 1, substrates 1a-3a and
6a-9a). To clarify this subtle aspect of the reaction in water, we
undertook a set of experiments designed to compare the ratios
As mentioned above, by plotting [n-C6F13H]/[1a] vs
[(Me3Si)3SiH]/[ 1-hexene], a straight line, whose slope repre-
sents (kH/kadd 1-hexene, is obtained (with a value of 1.55 (
)
0.09, r2 = 0.998). The intercept of this plot shows, remark-
ably, no deviation from the ideal value of zero, purporting
•
that the only source of n-C6F13 radical reduction (i.e.,
n-C6F13H) is the silane, and not the solvent or the alkene.31
of (kH/kadd 1-hexene and (kH/kadd)acrylonitrile for the addition
)
3. Conclusions
reaction of n-C6F13I to the electron rich 1-hexene and electron
deficient acrylonitrile, respectively. These ratios of rate constants
are obtained by plotting [n-C6F13H]/[1a] vs [(Me3Si)3SiH]/
[1-hexene] and [n-C6F13H]/[6a] vs [(Me3Si)3SiH]/[acrylonitrile],
respectively, when the reactions are initiated thermally, by
using incremental amounts of (Me3Si)3SiH, and keeping the
alkene and n-C6F13I concentrations constant. We obtained
slopes for both plots equal to 1.55 ( 0.09 (r2 = 0.998)
It is interesting to point out that the scope of the radical
dioxygen initiation reactions with silanes in water has been
extended from the use in hydrosilylation reactions of C-C
(36) (a) Litwinienko, G.; DiLabio, G. A.; Mulder, P.; Korth, H.-G.;
Ingold, K. U. J. Phys. Chem. A 2009, 113, 6275–6288. (b) Nielsen, M. F.;
Ingold, K. U. J. Am. Chem. Soc. 2006, 128, 1172–1182. (c) Snelgrove, D. W.;
Lusztyk, J.; Banks, J. T.; Mulder, P.; Ingold, K. U. J. Am. Chem. Soc. 2001,
123, 469–477. (d) Avila, D. V.; Ingold, K. J. J. Am. Chem. Soc. 1995, 117,
2929–2930.
and 1.88 ( 0.19 (r2 = 0.989) for (kH/kadd 1-hexene
and
)
(37) [3]/[2] = kadd[1-hexene]/kH[(Me3Si)3SiH], where kadd is the rate
constant for of addition of perfluorinated radical to 1-hexene, kH is the rate
constant for H atom abstraction from the silane, and 2 and 3 are the reduced
perfluorinated alkane and the addition product, respectively, shown in eq 2.
(35) (a) Scaiano, J. C.; Stewart, L. C. J. Am. Chem. Soc. 1983, 105, 3609–
3614. (b) Johnston, L. J.; Scaiano, J. C.; Ingold, K. U. J. Am. Chem. Soc.
1984, 106, 4877–4881.
6146 J. Org. Chem. Vol. 75, No. 18, 2010

Barata-Vallejo and Postigo
JOCArticle
multiple bonds19,22 to the intermolecular radical carbon-
carbon bond formation.
and 2, eq 2). For this preliminary experiment, we used 1-hexene
as the alkene and n-C6F13I as the source of Rf• radicals.
Reduction product n-C6F13H and addition product C6F13-
C6H13 were both obtained under different reaction conditions
(by incremental amounts of (Me3Si)3SiH, and keeping alkene
and n-C6F13I concentrations constant), under thermal initia-
tion. The most favorable reaction conditions are obtained by
using a molar ratio of alkene:(Me3Si)3SiH:RfI equal to 25:2.5:5,
and this ratio was chosen as optimal.
From results obtained in Schemes 1-3 and Table 1, the
thermal ACCN-initiation is deemed a better radical initiat-
ing technique than the dioxygen-initiation, as opposed to
what has been observed in the radical hydrosilylation of
alkynes in water.19,22Also, the radical dioxygen initiation
methodology is a good option of choice, as fairly good yields
of carbon-carbon coupling products can be obtained in
water under the mild dioxygen initiation technique, in the
absence of reduced perfluorinated halides.
Interesting and notorious solvent effects can be invoked in
water on the rates of reactions of perfluoroalkyl radicals
toward alkenes and silicon hydrides, respectively, as opposed
to those found in benzene, where the latter rates are ca. 6
times faster at equal concentrations of silanes and alkenes.
Our account also provides a convenient method to achieve
perfluoroalkylation reactions of alkenes in water to render
perfluoroalkylated alkanes as key intermediates in the synthe-
sis of fluorophors and other fluorinated materials. We are
currently studying competition reactions between radical
additions and H abstraction processes in water.
The procedure is the following: In a 5 mL conical vial, pro-
vided with a conical stir bar, a heterogeneous aqueous (5 mL)
mixture of the alkene (20-25 ꢀ 10-5 mol), (Me3Si)3SiH (2.5 ꢀ
10-5 mol), the perfluoroalkyl halide (5 ꢀ 10-5 mol), and ACCN
(1.5 ꢀ 10-5 mol) is flushed with Ar for 10 min before heating at
70 °C for 2-4 h unless otherwise indicated. After the reaction
time elapsed, addition of pentane, and extraction, the organic
phase is analyzed. Perfluoroalkylated products are isolated and
purified by distillation under reduced pressure with use of a
short path distillation apparatus, and characterized by standard
spectroscopic techniques. The purity of products is checked by
gas chromatography, and in some cases redistilled or silica gel
chromatographed.
Dioxygen Initiation19. A balloon filled with pure oxygen
connected to the vessel where no apparent bubbling resulted
allowed dioxygen to be introduced, in the reaction vessel, up to
its solubility limits in water.
4. Experimental Section
The dioxygen-initiated radical-induced reactions of alkenes
with perfluoroalkyl halides in Ar-degassed water are carried out
by adding subsequently (Me3Si)3SiH (2.5 ꢀ 10-5 mol), the
alkene (20-25 ꢀ 10-5 mol), and the perfluoroalkyl halide37 (5 ꢀ
10-5 mol) in a conical vial provided with a conical stir bar, filled
with 5 mL of Milli-Q water previously deoxygenated with a
stream of Ar for 10 min. The vessel is tight-sealed, connected
with a balloon filled with 99.99% dioxygen, and vigorously
stirred at 20 °C (36 h). As a slight positive oxygen pressure is
exerted on the reaction vessel, air does not leak in the system.
The mechanism for the unusual reaction of (Me3Si)3SiH with
oxygen has been investigated before38a and applied successfully
in water.19,22
General Methods. The internal standard method was used for
quantitative GC analysis with use of authentic samples, and one
of the following capillary columns was employed: HP-1 (5 m ꢀ
0.53 mm i.d.) or HP-1 (30 m ꢀ 0.32 mm i.d.). Oven program:
starting at 50 °C for 5 min, followed by an increase of 5 deg/min
1
up to 250 °C. NMR spectra were recorded at 400 (for H) or
100.6 MHz (for 13C) in CDCl3 as deuterated solvent and
referenced with the residual solvent peak at 7.26 ppm in the
1H NMR spectra and 77.0 ppm (CDCl3) in the 13C NMR
spectra. Hydrogen multiplicity (CH, CH2, CH3) information
was obtained from carbon DEPT-135 experiments for com-
pounds 1c, 7a, 7d, and 8d. Some NMR spectral connectivity
data were confirmed by 1H-13C HSQC and HMBC 2-D
experiments. Reduced pressure distillation employed a bulb-
to-bulb distillation apparatus with four glass bulbs. When
necessary, compounds were isolated by flash chromatography
performed on silica gel. High-resolution mass spectrometry
measurements were performed with a resolution of 1-5 ppm.
Water was obtained from a milli-pore system, and extraction
and chromatographic solvents were HPLC-grade. Products
from Schemes 1-4 and Table 1 were characterized by standard
spectroscopic techniques and compared with spectral data from
the literature when available.
Materials. Perfluoroalkyl iodides and bromides were com-
mercially available and used as received from the supplier.
Alkene substrates were also commercially available and used
as received from the supplier, except for styrene, 4-methylsty-
rene, acrylonitrile, crotonaldehyde, methyl acrylate, and vinyl
methyl ketone, which were previously distilled and stored over
molecular sieves (4 A) prior to use.
Methods of Radical Initiation in Water: Study of the Reaction
Stoichiometry. Initiation by Thermal Decomposition of an Azo
Compound. The water-insoluble radical initiator 1,10-azobis-
(cyclohexanecarbonitrile) (ACCN; half-life of 2.33 h at 100 °C)
has been found to give the best performance for both hydro-
phobic and hydrophilic substrates22 in our initial studies and
this trend has been confirmed by the present results.
Spectroscopic Characterization of Known Compounds 1a-
6a,25-28 9a,28 10a,25c 1b,31 1d,25b 2d,25b 3d, 4d,39,40,41a 5d,40,41
6d,28,32 8d,33 9d,28 1e,25b,42c 2e,25b,42c, 3e,42c 4e,26 6e,28 9e28,34
.
These compounds were characterized from comparison of their
1H and 13C NMR data with those found in the literature
(references of compounds throughout the text).
Spectroscopic Characterization of Unknown Compounds 7a,
8a, 1c, 7d, 5e, 7e, and 8e. 7a (4,4,5,5,6,6,7,7,8,8,9,9,9-trideca-
fluoro-3-methylnonanal): yellowish oil. GC/MS EI, m/z (%)
390 (32), 375 (21), 373 (12), 362 (29), 320 (39), 273 (100). EI-
HRMS Anal. Calcd for C10H7F13O 390.0289, found 390.0296.
Elemental analyses: Found: C (30.05%), H (1.71%), O (4.21%).
Calcd for C11H7F13O: C (30.79%), H (1.81%), F (63.31%), O
(4.10%). FT-IR (ν, cm-1) 1795 (CdO), 1204, 1140. 1H NMR δH
(38) (a) Zaborovskiy, A. B.; Lutsyk, D. S.; Prystansky, R. E.; Kopylets,
V. I.; Timokhin, V. I.; Chatgilialoglu, C. J. Organomet. Chem. 2004, 689,
~
2912–2919. (b) Postigo, A.; Nudelman, N.; Calandra, J.; Terenas, J. J.;
Russo, D. Different Radical Initiation Techiques of Hydrosilylation Reac-
tions of Multiple Bonds in Water: Photochemical Initiation. J. Phys. Org.
Chem. DOI: 10.1002/poc.1732. Published Online: July 15, 2010.
(39) Shimizu, R.; Yoneda, E.; Fuchikami, T. Tetrahedron Lett. 1996, 37,
5557–5560.
(40) Darses, S.; Pucheault, M.; Genet, J.-P. Eur. J. Org. Chem. 2001, 6,
1121–1128.
(41) (a) Avila, D. V.; Ingold, K. U.; Lusztyk, J.; Dolbier, W. R.; Pan,
H.-Q.; Muir, M. J. Am. Chem. Soc. 1994, 116, 99–104. (b) Herve, A.;
Rodriguez, A. L.; Fouquet, E. J. Org. Chem. 2005, 70, 1953–1956.
(42) (a) Tedder, J. M. Tetrahedron 1982, 38, 313–329. (b) Broniatowski,
M.; Macho, I. S.; Minones, J.; Dynarowicz-Latka, P. J. Phys. Chem. B 2004,
108, 13403–13411. (c) Broniatowski, M.; Dynarowicz-Latka, P.; Witko, W.
J. Fluorine Chem. 2005, 126, 79–86.
A preliminary set of experiments were conducted in order to
adjust the right stoichiometry of the radical addition reactions
of Rf• radicals to alkenes so as to favor the radical addition
product over the reduction product in water (as in products 3
J. Org. Chem. Vol. 75, No. 18, 2010 6147

Barata-Vallejo and Postigo
638.0525, found 638.0534. Elemental analyses. Found:
(35.55%), H (1.88%). Calcd for C19H11F21: C (35.75%), H
JOCArticle
ppm (400.13 MHz, CDCl3) 1.34 (d, 3H, Me), 2.69 (complex m,
C
3 H, CH and CH2), 9.51 (s, 1 H, CHO). 13C NMR δ ppm
13C
(100.6 MHz, CDCl3) 11.3, 39.7, 43.0, 100-130 (13C-19F coup-
ling from (CF2)6), 203.4.
(1.74%), F (62.51%). H NMR δH ppm (400.13 MHz, CDCl3)
1
2.07 (s, 3 H, CH3-Ph), 2.40 (complex m, 2 H, CH2), 2.96 (complex
8a (methyl 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononanoate):
colorless oil. GC/MS EI, m/z (%) 406 (2), 391 (15), 373 (11), 354
(21), 347 (25), 319 (100), 87 (67). EI-HRMS Anal. Calcd for
C10H7F13O2 406.0238, found 406.0240. Elemental analyses.
Found: C (29.54), H (1.75%), O (7.81%). Calcd for C9H5F13O2:
C (29.57%), H (1.74%), F (60.81%), O (7.88%). FT-IR
m, 2 H, CH2-Rf), 7.01 (m, 2 H, Ph), 7.23 (m, 2 H, Ph). 13C NMR
δ
13C ppm (100.6 MHz, CDCl3) 21.1, 27.0, 33.1, 100-120 (13C-19F
coupling from (CF2)10), 128.45, 128.11, 135.11, 137.51.
7e (4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13,13-henico-
safluoro-3-methyltridecanal): yellowish oil. GC/MS EI, m/z
(%) 590 (5), 575 (32), 571 (12), 562 (59), 519 (55), 471 (100).
EI-HRMS Anal. Calcd for C14H7F21O 590.0162, found
590.0156. Elemental analyses. Found: C (27.29%), H (1.29%),
O (2.65%). Calcd for C14H7F21O: C (28.49%), H (1.20%), F
(67.60%), O (2.71%). FT-IR (ν, cm-1) 1800 (CdO), 1206, 1143.
1H NMR δH ppm (400.13 MHz, CDCl3) 1.33 (d, 3 H, J = 7 Hz,
CH3), 2.65 (complex m, 3 H, CH-Rf and CH2-CHO), 9.11 (s,
CHO). 13C NMR δ13C ppm (100.6 MHz, CDCl3) 11.2, 40.4, 44.5,
95-135 (13C-19F coupling from (CF2)10), 200.21 (CHO).
8e (methyl 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13,13-
henicosafluorotridecanoate): colorless oil. GC/MS EI, m/z (%)
606 (5), 591 (35), 587 (13), 578 (54), 575 (12), 519 (51), 487 (100),
387 (21). EI-HRMS Anal. Calcd for C14H7F21O2 606.0111,
found 606.0103. Elemental analyses. Found: C (26.94%), H
(1.07%), O (5.39%). Calcd for C14H7F21O2: C (27.74%), H
(1.16%), F (65,82%), O (5.28%). FT-IR (ν, cm-1) 1798 (CdO),
1717, 1446, 1209, 1143. 1H NMR δH ppm (400.13 MHz, CDCl3)
2.15 (complex m, 2 H, CH2-Rf), 2.55 (complex m, 2 H,
1
(ν, cm-1) 1800 (CdO), 1527, 1302, 1209, 1143. H NMR δH
ppm (400.13 MHz, CDCl3) 2.24 (complex m, 2 H, CH2-Rf),
2.61 (complex m, 2 H, CH2-COOMe), 3.62 (s, 3 H, CH3). 13
C
NMR δ13C ppm (100.6 MHz, CDCl3) 26.2 (br. s, CH2-COOMe),
27.5 (m, CH2-Rf), 51.0, 100-130 (13C-19F coupling from
(CF2)6), 176.0 (CO).
1c (1,1,2,2,3,3,4,4-octafluoro-1-iododecane): pinkish oil. GC/
MS EI, m/z (%) 413 (10), 412 (4), 335 (58), 327 (43), 285 (100),
185 (45). EI-HRMS Anal. Calcd for C10H13F8I 411.9934, found
411.9940. Elemental analyses. Found: C (29.24%), H (3.92%).
Calcd for C10H13F8I: C (29.14%), H (3.81%), F (36.86%), I
(30.79%). 1H NMR δH ppm (400.13 MHz, CDCl3) 0.79 (t, 3 H,
J = 7 Hz, CH3), 1.32 (complex m, 2 H, CH2-CH3), 1.39
(complex m, 2 H), 1.60 (complex m, 1 H, CH-HRf), 1.90
(complex m, 1 H, CH-HRf). 13C NMR δ13C ppm (100.6 MHz,
CDCl3) 13.9, 20.6, 22.1, 28.9, 30.3, 31.7, 80-120 (13C-19F
coupling from (CF2)4).
7d (4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoro-3-
methylundecanal): yellowish oil. GC/MS EI, m/z (%) 490 (12),
471 (23), 462 (100), 420 (100), 371 (55), 271 (87). EI-HRMS
Anal. Calcd for C12H7F17O 490.0225, found 490.0220. Elemen-
tal analyses. Found: C (29.10%), H (1.49%), O (3.33%). Calcd
for C12H7F17O: C (29.40%), H (1.44%), F (65.89%), O (3.26%).
CH2-COOMe), 3.56 (s, 3 H, CH3-COO). 13C NMR δ
13C
ppm (100.6 MHz, CDCl3) 26.2, 27.2, 52.6, 100-130 (13C-19F
coupling from (CF2)10), 176.55.
Acknowledgment. Thanks are given to financial agencies
such as Conicet-Argentina, and Agencia Nacional de
1
FT-IR (ν, cm-1) 1798 (CdO), 1689, 1209, 1145. H NMR δH
ꢀ
ꢀ
Promocion Cientıfica y Tecnica, Argentina, PICTO-CRUP
30891 is gratefully acknowledged.
´
ppm (400.13 MHz, CDCl3) 1.30 (t, 3 H, J = 6.7 Hz, CH3), 2.80
C
(complex m, 3 H, CH-Rf and CH2-CHO), 9.61 (s, CHO). 13
NMR δ13C ppm (100.6 MHz, CDCl3) 12.0, 40.3, 41.6, 100-135
(13C-19F coupling from (CF2)8), 200.5 (CHO).
Supporting Information Available: 1H NMR and 13C NMR
spectra of compounds 1a through 9a, as well as spectral char-
acterization of 1b, 1c, compounds 1d through 9d, and com-
pounds 1e through 9e. This material is available free of charge
via the Internet at http://pubs.acs.org.
5e (1-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-henico-
safluorododecyl)-4-methylbenzene): colorless oil. GC/MS EI,
m/z (%) 638 (5), 623 (41), 619 (21), 519 (100), 419 (23), 319 (33),
92 (54), 77 (51), 65 (11). EI-HRMS Anal. Calcd for C19H11F21
6148 J. Org. Chem. Vol. 75, No. 18, 2010