Separation of "light fluorous" reagents and catalysts by fluorous solid-phase extraction: Synthesis and study of a family of triarylphosphines bearing linear and branched fluorous tags

Article abstract of DOI:10.1021/jo000464f

Practical syntheses of new triarylphosphines bearing both linear and branched fluorous tags (Rf) are reported. The phosphines have one, two, or all three aryl rings bearing fluorous tags: (Ph)_3-nP(C₆H₄ (CH₂)_mRf)_n. Fluorous-organic partition coefficients have been measured and the retention properties of both the phosphines and the derived phosphine oxides on fluorous reverse phase silica have been studied. While applications relying on liquid-liquid extractive separations of these phosphines may be limited to those bearing three fluorous chains, the technique of solid phase extraction should be broadly applicable to phosphines, phosphine oxides, and derived metal complexes. A parallel platinum-catalyzed allylation of aldehydes with fluorous allyl stannanes illustrates the usefulness of the new fluorous ligands in small-scale synthesis.

Full text of DOI:10.1021/jo000464f

8866
J . Org. Chem. 2000, 65, 8866-8873
Sep a r a tion of “Ligh t F lu or ou s” Rea gen ts a n d Ca ta lysts by
F lu or ou s Solid -P h a se Extr a ction : Syn th esis a n d Stu d y of a F a m ily
of Tr ia r ylp h osp h in es Bea r in g Lin ea r a n d Br a n ch ed F lu or ou s Ta gs
Qisheng Zhang, Zhiyong Luo, and Dennis P. Curran*
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
Received March 28, 2000
Practical syntheses of new triarylphosphines bearing both linear and branched fluorous tags (Rf)
are reported. The phosphines have one, two, or all three aryl rings bearing fluorous tags:
(Ph)3-nP(C6H4(CH2)mRf)n. Fluorous-organic partition coefficients have been measured and the
retention properties of both the phosphines and the derived phosphine oxides on fluorous reverse
phase silica have been studied. While applications relying on liquid-liquid extractive separations
of these phosphines may be limited to those bearing three fluorous chains, the technique of solid
phase extraction should be broadly applicable to phosphines, phosphine oxides, and derived metal
complexes. A parallel platinum-catalyzed allylation of aldehydes with fluorous allyl stannanes
illustrates the usefulness of the new fluorous ligands in small-scale synthesis.
In tr od u ction
erties more similar to their organic parents. While
reduction of the fluorine content can allow the use of
standard literature reaction conditions with little or no
modification, this quickly compromises the separation of
fluorous from nonfluorous components by liquid-liquid
extraction. However, the recently introduced technique
of fluorous solid-phase extraction4 is proving far superior
to liquid-liquid extractions for compounds with fewer
fluorines. Light fluorous techniques are especially useful
for small-scale and discovery-oriented research, including
parallel synthesis applications5 and so-called techniques
of fluorous synthesis.6
Fluorous techniques for the synthesis of small organic
molecules are becoming increasingly useful as more and
more fluorous compounds are synthesized and studied.1
These techniques are attractive for strategic separation
of reaction mixtures since fluorous-tagged compounds can
be quickly separated from nontagged compounds in
binary liquid-liquid and solid-liquid extractions.2 The
fluorine content of a fluorous molecule is a crucial feature
that must be balanced to obtain suitable performance
during both the reaction and the separation. The oppos-
ing needs at these two stages are beginning to divide the
fluorous field into two branches, which we have recently
termed “heavy fluorous” and “light fluorous”. As Figure
1 illustrates, these two techniques are ends of a con-
tinuum with a considerable gray area in between.
On the heavy end, the original fluorous biphasic
catalysis (FBC) and allied techniques3 strive for very high
partition coefficients in liquid-liquid separation. This
requires fluorous reagents and catalysts with large
numbers of fluorines. While this ensures easy separation,
the large numbers of fluorines tend to render the fluorous
compounds insoluble in typical organic reaction solvents,
and fluorous cosolvents are used. These solvents have
poor dissolving power for organic compounds, so the
modification and optimization of reaction conditions is
often required. However, once suitable conditions are
found, the resulting heavy fluorous techniques are very
powerful, especially when applied to catalytic reactions.
Fluorous biphasic catalysis was the original fluorous
technique introduced in 1994 by Horva´th and Ra´bai,7 and
this technique is catching on in the catalysis community.
Most of the work in this area involves the use of fluorous
phosphines and phosphites.8 The original trialkylphos-
phine ligand [P(CH2CH2C6F13)3] introduced by Horva´th
and Ra´bai has proved useful in a number of reactions
catalyzed by rhodium and iridium.9 More recently, a
number of fluorous analogues of triphenylphosphine have
appeared, and several of these are shown in Figure 2.
Phosphine 1a was introduced by Leitner for reactions in
(4) (a) Curran, D. P.; Hadida, S.; He, M. J . Org. Chem. 1997, 62,
6714. (b) Curran, D. P.; Luo, Z. Y. J . Am. Chem. Soc. 1999, 121, 9069.
(c) Curran, D. P.; Hadida, S.; Kim, S. Y.; Luo, Z. Y. J . Am. Chem. Soc.
1999, 121, 6607. (d) Curran, D. P.; Hadida, S.; Studer, A.; He, M.; Kim,
S.-Y.; Luo, Z.; Larhed, M.; Hallberg, M.; Linclau, B. In Combinatorial
Chemistry: A Practical Approach; Fenniri, H., Ed.; Oxford Univ
Press: Oxford, in press; Vol. 2.
On the light end, the goal is to reduce the number of
fluorines to provide fluorous compounds that have prop-
(5) Curran, D. P. Med. Res. Rev. 1999, 19, 432.
(6) (a) Studer, A.; Hadida, S.; Ferritto, R.; Kim, S. Y.; J eger, P.; Wipf,
P.; Curran, D. P. Science 1997, 275, 823. (b) Curran, D. P. Cancer J .
1998, 4 Supp. 1, S73.
(1) Curran, D. P. In Stimulating Concepts in Chemistry, Shibasaki,
M., Stoddart, J . F., Voglte, F., Eds.; VCH: New York, in press.
(2) Curran, D. P. Angew. Chem., Int. Ed. Engl. 1998, 37, 1175.
(3) (a) Horva´th, I. T. Acc. Chem. Res. 1998, 31, 641. (b) de Wolf, E.;
van Koten, G.; Deelman, B. J . Chem. Soc. Rev. 1999, 28, 37. (c)
Cavazzini, M.; Montanari, F.; Pozzi, G.; Quici, S. J . Fluorine Chem.
1999, 94, 183. (d) Fish, R. H. Chem. Eur. J . 1999, 5, 1677. (e)
BarthelRosa, L. P.; Gladysz, J . A. Coord. Chem. Rev. 1999, 192, 587.
(f) Betzemeier, B.; Knochel, P. In Topics in Current Chemistry, “Modern
Solvents in Organic Synthesis”; Knochel, P., Ed.; Springer-Verlag:
Berlin, 1999; Vol. 206; p 62.
(7) Horva´th, I. T.; Ra´bai, J . Science 1994, 266, 72.
(8) Mathivet, T.; Monflier, E.; Castanet, Y.; Mortreux, A.; Couturier,
J . L. Tetrahedron Lett. 1999, 40, 3885.
(9) (a) Guillevic, M. A.; Rocaboy, C.; Arif, A. M.; Horva´th, I. T.;
Gladysz, J . A. Organometallics 1998, 17, 707. (b) Horva´th, I. T.; Kiss,
G.; Cook, R. A.; Bond, J . E.; Stevens, P. A.; Rabai, J .; Mozeleski, E. J .
J . Am. Chem. Soc. 1998, 120, 3133. (c) J uliette, J . J . J .; Rutherford,
D.; Horva´th, I. T.; Gladysz, J . A. J . Am. Chem. Soc. 1999, 121, 2696.
(d) Li, C. B.; Nolan, S. P.; Horva´th, I. T. Organometallics 1998, 17,
452. (e) Smith, D. C.; Stevens, E. D.; Nolan, S. P. Inorg. Chem. 1999,
38, 5277.
10.1021/jo000464f CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/01/2000

Separation of “Light Fluorous” Reagents and Catalysts
J . Org. Chem., Vol. 65, No. 26, 2000 8867
F igu r e 1. The effect of the size of the fluorous tag on reaction and separation.
metallic complexes of these ligands.13 Ligands with a silyl
spacer (see 4a ) have been synthesized and studied by van
Koten and co-workers.14
An important conclusion drawn from most of these
studies on phosphines as well as studies on other classes
of ligands has been that more fluorines are needed rather
than fewer for fluorous reactions. It seems generally
accepted that 39 fluorines is a minimum useful level, and
more fluorines may be needed in a number of cases. Our
work on light fluorous techniques4b,c led us to suppose
that this generalization was premature. We hypothesized
that more lightly fluorinated phosphines and relatives
such as phosphine oxides and organometallic complexes
would be readily separable from organic reaction com-
ponents by fluorous solid-phase extraction. We therefore
undertook the synthesis and study of two related families
of linear (1a -c) and branched (5a -c) fluorous phos-
phines shown in Figure 2. We have indeed found that
phosphines and derivatives with fewer than 39 fluorines
are well-retained on fluorous reverse phase silica gel. Our
work suggests that many of the previously synthesized
fluorous compounds that have been pronounced dead
because they have too few fluorines for liquid-liquid
extraction techniques can be resurrected for use with
solid-liquid extractive workups.
Resu lts a n d Discu ssion
The impetus to synthesize and study fluorous-tagged
phosphines emerged from our recent study on allylations
with fluorous allylstannane.15 Reagents 6a ,b bearing a
propylene spacer were prepared and used in the platinum-
catalyzed allylation shown in eq 1. Small libraries of
alcohols were conveniently prepared by parallel synthesis
with separation of the fluorous tin residues by solid-phase
extraction over fluorous reverse-phase silica gel. Lewis
F igu r e 2. Known fluorocarbon-tagged triarylphosphines.
(13) (a) Fawcett, J .; Hope, E. G.; Kemmitt, R. D. W.; Paige, D. R.;
Russell, D. R.; Stuart, A. M.; ColeHamilton, D. J .; Payne, M. J . Chem.
Commun. 1997, 1127. (b) Bhattacharyya, P.; Gudmunsen, D.; Hope,
E. G.; Kemmitt, R. D. W.; Paige, D. R.; Stuart, A. M. J . Chem. Soc.,
Perkin Trans. 1 1997, 3609. (c) Fawcett, J .; Hope, E. G.; Kemmitt, R.
D. W.; Paige, D. R.; Russell, D. R.; Stuart, A. M. J . Chem. Soc., Dalton
Trans. 1998, 3751. (d) Hope, E. G.; Kemmitt, R. D. W.; Stuart, A. M.
J . Chem. Soc., Dalton Trans. 1998, 3765. (e) Sinou, D.; Pozzi, G.; Hope,
E. G.; Stuart, A. M. Tetrahedron Lett. 1999, 40, 849. (f) Hope, E. G.;
Kemmitt, R. D. W.; Paige, D. R.; Stuart, A. M.; Wood, D. R. W.
Polyhedron 1999, 18, 2913. (g) Hope, E. G.; Kemmitt, R. D. W.; Paige,
D. R.; Stuart, A. M. J . Fluorine Chem. 1999, 99, 197.
(14) (a) Richter, B.; Deelman, B. J .; van Koten, G. J . Mol. Catal. A
Chem. 1999, 145, 317. (b) Richter, B.; Spek, A. L.; vanKoten, G.;
Deelman, B. J . J Am. Chem. Soc. 2000, 122, 3945. (c) Richter, B.;
deWolf, E.; vanKoten, G.; Deelman, B. J . J . Org. Chem. 2000, 65, 3885.
(d) deWolf, E.; Richter, B.; vanKoten, G.; Deelman, B. J . J . Org. Chem.
2000, 65, 5424.
supercritical carbon dioxide10 and has also found use in
an FBC variant of the popular palladium-catalyzed allylic
substitution (Tsuji/Trost) reaction.11 Related phosphine
2a lacking the ethylene spacer has been used by Knochel
as a ligand for palladium-catalyzed Negishi couplings and
Heck reactions.12 Hope and co-workers have prepared
families of phosphines bearing only one, two, and three
fluorous chains in both the para (2a -c) and meta (3a -
c) series and studied the properties of several organo-
(10) Kainz, S.; Koch, D.; Baumann, W.; Leitner, W. Angew. Chem.,
Int. Ed. Engl. 1997, 36, 1628.
(11) Kling, R.; Sinou, D.; Pozzi, G.; Choplin, A.; Quignard, F.; Busch,
S.; Kainz, S.; Koch, D.; Leitner, W. Tetrahedron Lett. 1998, 39, 9439.
(12) Betzemeier, B.; Knochel, P. Angew. Chem., Int. Ed. Engl. 1997,
36, 2623.
(15) (a) Curran, D. P.; Luo, Z.; Degenkolb, P. Bioorg. Med. Chem.
Lett. 1998, 8, 2403. (b) Curran, D. P.; Luo, Z. Med. Chem. Res. 1998,
8, 261. (c) Ryu, I.; Niguma, T.; Minakata, S.; Komatsu, M.; Luo, Z. Y.;
Curran, D. P. Tetrahedron Lett. 1999, 40, 2367.

8868 J . Org. Chem., Vol. 65, No. 26, 2000
Zhang et al.
acid catalyzed and radical allylations were also conducted
with the propylene-spaced tin reagents (not shown),15 and
these were clearly superior to their lower homologues
with ethylene spacers. While the radical and Lewis acid
procedures proved very practical for parallel synthesis,
the platinum-catalyzed procedure did not. This is because
the fluorous solid-phase extraction does not separate any
remnant of the catalyst from the desired organic products
in eq 1. To solve this problem, we have prepared a series
of fluorous phosphines, converted these into platinum
catalysts, and then restudied the allylation to ascertain
whether ligand-free products could be obtained.
fluorocarbon fragments. These are of interest because
branched tags may confer improved solubility. In addi-
tion, the branched tags that we have prepared have no
C-H bonds â to fluorine. This design feature eliminates
any possible HF elimination reactions of the tag under
strongly basic conditions. To prepare the requisite aryl
bromides with branched tags, we modified a procedure
recently reported by Chambers and co-workers (eq 3).17
They found that reaction of p-bromobenzyl bromide and
perfluoroalkene 9 with cesium fluoride in sulfolane
provided the fluoroalkylated product 10 in 62% yield,
contaminated with substantial amounts of p-bromobenzyl
fluoride. We found that this direct fluoride substitution
product could be suppressed by using p-bromobenzyl
iodide and by changing the solvent to DMF. This reduced
the reaction time from 8 days to less than 4 days and
improved the yield of 10 to 89%.
The syntheses of two related series of phosphines are
shown in eqs 2 and 3. Phosphine 1a was already known
from the work of Leitner,10 and we originally used his
procedure to prepare it. However, during the course of
this work, several modifications were made to improve
its synthesis (eq 2). The Leitner protocol (not shown) for
synthesis of aryl bromide 8 calls for coupling of perfluo-
rohexylethyl iodide 7 with the Grignard reagent derived
from 1,4-dibromobenzene. This provides the aryl bromide
8 along with substantial amount of Wurtz coupled
product (C6F13CH2CH2CH2CH2C6F13). We developed a
convenient procedure to separate these on small scale by
using fluorous silica,16 but large-scale separation is
difficult because the two compounds have similar polari-
ties and boiling points. We found that palladium-
catalyzed coupling of an organozinc reagent derived from
7 with 1-iodo-4-bromobenzene gave a much cleaner
product 8. Little or no Wurtz coupled product was
obtained, provided that the temperature was not allowed
to rise above 25 °C during formation of the zinc reagent.
The coupling process was accomplished at 45 °C; again,
higher temperatures gave lower yields. Bromide 8 can
be reliably synthesized by this procedure in about 56%
yield (after distillation) on scales up to at least 30 g. The
lower homologue bearing a C4F9 group and the meta-
isomer were synthesized in comparable yields by the
same procedure (not shown).
Metalation of 10 and reaction with PCl3, PhPCl2, and
Ph2PCl then provided the phosphines 5a-c with branched
tags in acceptable yields (49-68%). In these experiments,
significant amounts of the phosphine oxides 12a -c were
also obtained (12-20%, see eq 4), and these could be
reduced to provide additional phosphine (see below). The
branched phosphines 5a -c are not isomers of the linear
phosphines 1a -c; they have one fewer CH2 group.
However, both series have the same number of “spacer”
carbons (2) between the aryl ring and the fluoroalkyl
group(s). Authentic samples of the phosphine oxides
11a -c derived from 1a -c were prepared in high yields
by standard oxidation with hydrogen peroxide, as shown
in eq 4.
Leitner prescribes the use of n-BuLi for the generation
and reaction of the lithium reagent derived from 8, but
we found improved results with t-BuLi. Halogen/lithium
exchange followed by quenching with PCl3 provided
Leitner’s phosphine 1a in 78% isolated yield. Likewise,
quenching with PhPCl2 and Ph2PCl provided the new
phosphines 1b and 1c in even higher yields.
31P NMR experiments showed that the chemical shifts
of the new phosphines (see Experimental Section) were
all in a narrow range between triphenylphosphine (δ )
As far as we know, there are currently no examples of
fluorous tags based on branched (rather than linear)
(16) Kainz, S.; Luo, Z. Y.; Curran, D. P.; Leitner, W. Synthesis 1998,
1425.
(17) Chambers, R. D.; Magron, C.; Sandford, G. J . Chem. Soc., Perkin
Trans. 1 1999, 283.

Separation of “Light Fluorous” Reagents and Catalysts
J . Org. Chem., Vol. 65, No. 26, 2000 8869
Ta ble 1. Reten tion Tim es (m in ) of P h osp h in es a n d
P h osp h in e Oxid es on a F lu ofix Colu m n a
Ta ble 2. P a r tition Coefficien ts of F lu or ou s Ar yl
P h osp h in es a t Room Tem p er a tu r e in 50/50 (v/v) of
F C-72/Or ga n ic Solven ts (P ) cflu or ou s p h a se/cor ga n ic p h a se
)
tR
FC-72/
methanol
FC-72/
THF
FC-72/
toluene
phosphine or phosphine oxide
a
b
c
compd
F content (wt %)
linear phosphines, 1a -c
38.9
37.7
42.5
38.9
29.8
28.3
30.0
27.9
13.9
10.6
12.6
9.1
1a
1b
1c
5a
5b
5c
57
52
41
59
53
42
30.03
1.86
0.12
18.48
3.34
0.09
0.08
0.05
0.02
0.51
1.05
0.01
0.75
0.05
0.05
6.84
0.18
0.12
linear phosphine oxides, 11a -c
branched phosphines, 5a -c
branched phosphine oxides 12a -c
a
Gradient: t ) 0 min, 80% MeOH; 20% H2O; t ) 30 min, 100%
MeOH; t ) 60 min, 90% MeOH, 10% THF.
-5.0) and tri(p-tolyl)phosphine) (δ ) -7.26). Indeed, the
range of 31P chemical shifts of our phosphines and all
those in Figure 2 is very small (<3 ppm).
comparable. Indeed, THF is a relatively powerful eluting
solvent for fluorous molecules, and we suspect that on
any absolute scale the gap between triply (a ) and doubly
(b) tagged molecules would be larger than the gap
between doubly (b) and singly (c) tag molecules. How-
ever, these gaps are so large as to make them difficult to
measure.
The phosphine oxides reliably eluted 1-3 min before
the analogous phosphines. This is because the phosphine
oxides have a lower fluorine content (on a percentage
basis) than the phosphines and (probably more impor-
tantly) because they are more polar. (Fluorous silica
tends to effect polar/nonpolar separation in a reverse-
phase fashion.) The comparison of the linear and branched
compounds is more interesting. With one fluorous tag,
the branched compound 5c emerges about 1 min before
the linear 1c; with two tags, the retention times of 5b
and 1b are nearly identical, and with three tags, the
linear compound 1a emerges almost 4 min before the
branched 5a . The trend for the corresponding phosphine
oxides is similar.
We also measured liquid-liquid partition coefficients
for all six phosphines between FC-72 and three organic
solvents (methanol, THF, and toluene).3e The procedure
involved a simple partitioning followed by HPLC analy-
sis, as described in the Experimental Section. Measure-
ments were reproducible within 10% or less, and the data
are shown in Table 2.
We next evaluated the phosphines and phosphine
oxides by analytical HPLC to assess their potential for
removal by solid-phase extraction. Pure samples were
injected on a commercial Fluofix column (bonded phase:
-Si(Me)2CH2CH2CH2C(CF3)2C3F7). Under isocratic condi-
tions, the compounds with differing numbers of fluorous
tags were so widely separated as to make collective
analysis impossible. We therefore employed a gradient
starting with 80% MeOH/H2O increasing to 100% MeOH
over 30 min (flow rate, 1.5 mL/min). THF was then
introduced in a second gradient to reach a final solvent
composition of 90% MeOH/10% THF after an additional
30 min.
The retention times of the tagged phosphines and
phosphine oxides are shown in Table 1. Triphenylphos-
phine and triphenylphosphine oxide come off with the
solvent front under these conditions (tR ) 1.6 min), and
experience suggests that most other organic compounds
would do likewise.4b The tagged phosphines and phos-
phine oxides then emerge in groups based on the number
of tags. This is expected since fluorous silica separates
molecules primarily by fluorine content. Molecules with
a single chain (“c” series) emerge at 9-14 min, those with
two chains (“b” series) emerge at 28-30 min, and those
with three chains (“a ” series) emerge at 38-42 min. Since
the solvent changes at 30 min (THF is introduced), the
absolute spacing between the groups is not directly
Only the triply fluorous phosphines 1a and 5a show
sufficiently high partition coefficients for separation by
liquid-liquid extraction, and only against methanol
(other polar organic solvents may also be suitable). THF
has good dissolving power for fluorous compounds and
not surprisingly provides low partition coefficients. Tolu-
ene is a very fluorophobic solvent with respect to fluorous
tin reagents [(RfCH2CH2)3SnX], but it has good dissolving
power for these phosphines (presumably due to the
aromatic rings), so low partition coefficients result. Van
Koten and co-workers have recently reported examples
where compounds with more fluorous chains had lower
partition coefficients than those with fewer, and we also
observed this phenomenon. Whether phosphines are
useful as ligands for removal of organometallic complexes
by liquid-liquid extraction is less clear. Presumably,
most monophosphine metal complexes will have a lower
partition coefficient than 1a and 5a themselves; however,
polyphosphine complexes could well have higher partition
coefficients.
Platinum catalysts were prepared from all six of the
phosphines by reaction with platinum dichloride, as
shown in eq 5. The catalysts were isolated in excellent
yields (82-86%) as white or yellow solids after recrys-
tallization from dichloromethane/ether, and each exhib-
ited the expected molecular ion peak in the mass spec-

8870 J . Org. Chem., Vol. 65, No. 26, 2000
Zhang et al.
Ta ble 4. P a r a llel Allyla tion s w ith 13b, 14a , a n d 14b
Ta ble 3. P a r a llel Allyla tion s w ith Ca ta lyst 13a
entry aldehydea catalyst % conversion % yield % purity
1
2
3
4
5
6
2,4-DNB
2,4-DNB
2,4-DNB
2-NP
2-NP
2-NP
13b
14a
14b
13b
14a
14b
100
100
100
69
74
73
92
98
96
89
89
94
98
99
99
99
99
95
entry
R
NMR yield (%) GC-MS purity (%)
1
2
3
4
5
6
7
8
2,4-dinitro
100
56
67
98
77
66
60
71
100
100
100
100
100
100
100
100
2,4-dichloro
2-chloro-5-nitro
2-nitro
2-trifluoromethyl
4-trifluoromethyl
2-bromo
a
2,4-DNB ) 2,4-dinitrobenzaldehyde; 2-NP ) 2-naphthalde-
hyde.
3-bromo
the solid-phase extraction could be optimized to remove
these traces by increasing the water content in the first
stage, but we have not yet done this.
trum. By analogy to the work of Hope,13b-d the catalysts
are assigned the cis geometry.
To better probe the utility of some of the other
catalysts, we conducted a parallel synthesis experiment
with two aldehydes and three catalysts: 13b, 14a , and
14b. The reaction and workup conditions were the same
as in Table 3, and the conversion (by 1H NMR), yield (by
1H NMR), and purity (by GC) of the products are shown
in Table 4. All three reactions with the more reactive 2,4-
dinitrobenzaldehyde worked very well and essentially
gave pure products in nearly quantitative yields. The
three reactions with 2-naphthaldehyde were not com-
plete, however, but the only detectable contaminant in
the product was the starting aldehyde. (Reactions with
naphthaldehyde can be driven to completion by heating
for 3 days.) Importantly, the solid-phase extractive
workup served to remove all fluorous tin and catalyst
residues as judged by proton NMR.
Catalysts 13 and 14 have good solubility in typical
organic solvents, and to show that fluorinated solvents
or cosolvents are not required, we conducted a reaction
of 2,4-dinitrobenzaldehyde and allylstannane 6 with
catalyst 14b under the standard literature conditions in
THF (without BTF). The reaction proceeded smoothly
over 24 h and gave the product in 92% yield. The ability
to directly apply literature reaction conditions with little
or no modification is an especially attractive feature of
light fluorous molecules.
Finally, we conducted one experiment to probe whether
the catalyst or ligand could be recovered from the solid-
phase extraction. To remove the fluorous tin residue from
the fluorous fraction, we used allyltributylstannane in
place of 6b. This stannane was coupled with 2,4-dini-
trobenzaldehyde in THF by using catalyst 14b, followed
by solid-phase extraction. Initial elution with 90% MeOH/
H2O provided the alcohol product contaminated (as
expected) with the tributyltin product (presumably Bu3-
SnOSnBu3). Continued elution with MeOH provided a
little more tin residue. Subsequent elution with THF
provided a trace of phosphine oxide 11b mixed with other
unidentified products, while subsequent elution with
hexane and FC-72 provided nearly nothing. Apparently,
neither the catalyst nor the ligand are recyclable under
these conditions, and at this point we do not know what
their fate is.
We initially tested the catalyst 13a with three linear
fluorous chains in allylations with the fluorous allylstan-
nane 6b to see if it solved the problem of catalyst
contamination of the organic product identified in eq 1.
The results of a series of parallel experiments are shown
in Table 3. A BTF solution of an aldehyde, fluorous
allylstannane 6b, and catalyst 13a (5 mol %) was heated
for 24 h at 60 °C. The solution was concentrated and the
residue was charged to fluorous reverse phase silica gel.
The silica was eluted with 90% methanol-water to give
an organic fraction which was evaporated and analyzed
for yield (by NMR against an internal standard) and
purity (by GC). All eight products were formed in good
yields (60-100%) and excellent purities (every product
gave a single peak on GC analysis). Neither fluorous tin
resonances nor phosphine resonances could be detected
in the 1H NMR spectra of the products. This is in contrast
to the experiments in eq 1, where aromatic phosphine
resonances were clearly visible in the spectrum of the
organic product. Similar experiments (not shown) also
suggested that 13b was an effective catalyst and provided
pure product. Catalyst 13c also promoted the reaction,
but traces of fluorous phosphine resonances were evident
in the NMR spectrum of the organic product. On the basis
of the HPLC retention times in Table 1, we believe that
Con clu sion s
We have described practical methods to synthesize new
fluorous triarylphosphines bearing one, two, or three

Separation of “Light Fluorous” Reagents and Catalysts
J . Org. Chem., Vol. 65, No. 26, 2000 8871
bp 79.1-80.9 °C/0.03 mmHg; 1H NMR (300 MHz, CDCl3) δ
2.36 (tt, J ) 18.3, 9.1 Hz, 2H), 2.86-2.92 (m, 2H), 7.11 (d, J )
8.4 Hz, 2H), 7.45 (d, J ) 8.4 Hz, 2H); 13C NMR (75 MHz,
CDCl3) δ 26.1, 32.9 (t, J FC ) 22.1 Hz), 105.5-123.2 (m, C6F13),
120.7, 130.1, 132.1, 138.3; 19F NMR (282.4 MHz, CDCl3) δ
-125.6 (2F), -122.9 (2F), -121.7 (2F), -120.7 (2F), -113.4
(2F), -79.6 (3F); IR (CHCl3) 3065, 2954, 2879, 1490, 1237,
1145, 1013, 810 cm-1; EIMS m/z 502/504 (M+), 423, 169/171
(M - C6F13CH2)+.
fluorous tags. The tags can be linear or branched, and
the resulting phosphines and phosphine oxides are well-
retained on fluorous reverse-phase silica gel under condi-
tions where most organic compounds elute with the
solvent front. The compounds with three fluorous chains
can probably be removed by FC-72 extractions against
polar solvents. Despite the low liquid-liquid partition
coefficients, all compounds appear practical for solid-
liquid extractions. Platinum catalysts derived from the
ligands have good organic solubility and promote allyla-
tions of aldehydes with a fluorous allylstannane, but all
the fluorous components of the reaction mixtures (includ-
ing the catalyst remnants) can be removed by solid-phase
extraction.
Beyond the introduction and study of new classes of
fluorous-tagged phosphines, the work described in this
paper has a number of more general implications. First
and perhaps foremost, the use of solid-phase extractions
is proving to be very general, and it allows one to reduce
the fluorous content of a tagged molecule. This is helpful
in discovery-oriented synthesis and parallel synthesis,
since it allows one to simply adopt standard reaction
conditions; there is no need to search for suitable
fluorinated solvents or cosolvents. Second, early work in
the fluorous biphasic catalysis area appears to have
underestimated the number of fluorine atoms needed to
secure high partition coefficients for liquid-liquid extrac-
tions in the aryl phosphine series, and the trend is toward
synthesizing phosphines with more fluorines. However,
existing “lightly fluorous” phosphines from several groups
will certainly be separable by fluorous solid-phase extrac-
tion, so their potential utility in small-scale and parallel
synthesis should not be overlooked. Finally, the method
used to make branched tagged arylphosphines in this
work should be useful for making other types of branched
fluorous reagents, protecting groups, etc. This will allow
the comparison of the relative merits of branched versus
linear tags for the first time.
1-Br om o-4-(3,3,4,4,5,5,5-h ep t a flu or o-2,2-bis(t r iflu or o-
m eth yl)p en tyl)ben zen e (10). A 250 mL, three-neck flask
was charged with perfluoro-2-methylpent-2-ene (27.0 g, 90
mmol), dry cesium fluoride (13.4 g, 88 mmol), and dry DMF
(65 mL) under argon. The solution was stirred at 45 °C for 36
h. 4-Iodobenzyl bromide (17.8 g, 59.9 mmol) was added, and
the mixture was heated at 65 °C for 14 h. The mixture was
cooled to room temperature and poured into a 2 L separatory
funnel with 1200 mL water. The organic layer was dried and
evaporated and the residue was loaded onto a silica gel column.
Eluting with hexanes-ethyl acetate (40:1) gave 10 (26.1 g,
89%) as a pale yellow liquid: 1H NMR (300 MHz, CDCl3) δ
3.43 (s, 2H), 7.17 (d, J ) 8.4 Hz, 2H), 7.45 (d, J ) 8.4 Hz, 2H);
13C NMR (75 MHz, CDCl3) δ 32.2, 61.6 (sept, J FC ) 24.7 Hz),
109.6-123.5 (m, C3F7), 122.1 (q, J FC ) 287.9 Hz), 122.7, 130.1,
131.6, 133.3; 19F NMR (282.4 MHz, CDCl3) δ -125.0 (2F),
-104.9 (2F), -79.3 (3F), -61.3 (6F); IR (CHCl3) 3062, 2985,
1596, 1494, 1332, 1257, 1111, 980, 885, 836, 746, 702 cm-1
;
EIMS m/z 488/490 (M+), 169/171 (M - C6F13)+.
Tr is-[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr id eca flu or ooctyl)p h en -
yl]p h osp h a n e (1a ). A solution of t-BuLi (1.7M in pentane,
5.6 mL, 9.5 mmol) was added slowly to 1-bromo-4-(3,3,4,
4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)benzene (8) (2.45 g, 4.9
mmol) in ether (50 mL) at -78 °C. After stirring at -78 °C
for 30 min, phosphorus trichloride (0.14 mL, 1.6 mmol) was
added. The mixture was warmed to room temperature over 2
h and stirred at room temperature for 2 h. The reaction
mixture was then quenched with water (5 mL). The ether layer
was separated. The aqueous layer was further extracted with
ether (10 mL) three times. The ether layers were combined,
dried over magnesium sulfate, and concentrated under vacuum.
The residue was then purified by column chromatography (20:
1, hexanes/ethyl acetate) on silica gel to yield 1a (1.58 g, 76%)
1
as a pale yellow solid: mp 49.9-52.4 °C; H NMR (300 MHz,
CDCl3) δ 2.38 (tt, J ) 18.0, 8.7 Hz, 6H), 2.90-2.96 (m, 6H),
7.19-7.29 (m, 12H); 13C NMR (75 MHz, CDCl3) δ 26.4, 32.9
(t, J FC ) 21.8 Hz), 107.7-121.5 (m, C6F13), 128.7 (d, J PC ) 7.0
Hz), 134.6 (d, J PC ) 18.8 Hz), 135.7 (d, J PC ) 10.5 Hz), 140.2;
19F NMR (282.4 MHz, CDCl3) δ -126.7 (6F), -124.0 (6F),
-123.4 (6F), -122.4 (6F), -115.2 (6F), -81.3 (9F); 31P NMR
(121.5 MHz, CDCl3) δ -6.65 (s); EIMS m/z 1300 (M+), 877,
513.
P h en ylbis[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr idecaflu or ooctyl)-
p h en yl]p h osp h a n e (1b). This was synthesized in a manner
similar to 1a : white solid; 90% yield; mp 42-43 °C; 1H NMR
(300 MHz, CDCl3) δ 2.31-2.48 (m, 4H), 2.91-2.97 (m, 4H),
7.20-7.36 (m, 13H); 13C NMR (75 MHz, CDCl3) δ 26.3, 32.8
(t, J FC ) 22.5 Hz), 105.2-121.4 (m, C6F13), 128.5, 128.6, 128.9,
133.6 (d, J PC ) 19.5 Hz), 134.2 (d, J PC ) 19.5 Hz), 135.5 (d,
J PC ) 9.5 Hz), 137.0 (d, J PC ) 9.5 Hz), 139.9; 19F NMR (282.4
MHz, CDCl3) δ -124.8 (4F), -122.3 (4F), -121.8 (4F), -120.7
(4F), -113.3 (4F), -79.7 (6F); 31P NMR (121.5 MHz, CDCl3) δ
-5.91 (s); EIMS m/z 954 (M+), 531, 477; HRMS for
C34H21F26P: calcd 954.0966, found 954.0950.
Dip h en yl[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr id eca flu or ooctyl)-
p h en yl]p h osp h a n e (1c). This was synthesized in a manner
similar to 1a : oi1; 81% yield; 1H NMR (300 MHz, CDCl3) δ
2.31-2.50 (m, 2H), 2.92-3.05 (m, 2H), 7.23-7.26 (m, 2H),
7.33-7.41 (m, 12H); 13C NMR (75 MHz, CDCl3) δ 26.4, 32.9
(t, J FC ) 21.7 Hz), 107.7-119.3 (m, C6F13), 128.6, 128.7, 128.9,
133.8 (d, J PC ) 19.5 Hz), 134.4 (d, J PC ) 19.5 Hz), 135.7 (d,
J PC ) 10.5 Hz), 137.3 (d, J PC ) 10.5 Hz), 139.9; 19F NMR (282.4
MHz, CDCl3) δ -125.0 (2F), -122.3 (2F), -121.7 (2F), -120.7
(2F), -113.5 (2F), -79.7 (3F); 31P NMR (121.5 MHz, CDCl3) δ
-5.11 (s); EIMS m/z 608 (M+), 183, 108.
Exp er im en ta l Section
Gen er a l. All air and/or moisture-sensitive reactions were
run under an atmosphere of argon. Tetrahydrofuran (THF)
and diethyl ether were freshly distilled from sodium benzophe-
none ketyl under nitrogen. Methylene chloride and N,N-
dimethylformamide (DMF) were distilled from calcium hydride
under nitrogen. HPLC analysis was performed on a Waters
2487 system using a Fluofix 120E column with detection by
UV.
1-Br om o-4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr id eca flu or ooctyl)-
ben zen e (8). To a 250 mL, three-neck flask equipped with
dropping funnel was added zinc powder (9.50 g, 146.2 mmol)
and dry THF (20 mL) under argon. 1,2-Dibromoethane (0.5
mL) was added and the mixture was heated at 65 °C for 2
min. The mixture was then cooled to room temperature.
Chlorotrimethylsilane (0.5 mL) was added and the mixture
was stirred at room temperature for 20 min. A solution of
3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl iodide (57.8 g, 126.6
mmol) in dry THF (100 mL) was added dropwise to keep the
temperature of the solution at room temperature. The reaction
mixture was stirred at room temperature for 12 h. The
colorless solution was then transferred via cannula to a
solution of 1-bromo-4-iodobenzene (35.8 g, 126.6 mmol) and
tetrakis(triphenylphosphine) palladium(0) (5.0 g, 4.3 mmol) in
THF (60 mL). After 24 h at 45 °C, the solvent was removed
under vacuum. The residue was dissolved in methylene
chloride (50 mL) and extracted with FC-72 (50 mL) six times.
The combined FC-72 layers were concentrated. Vacuum distil-
lation of the residue gave 8 (34.3 g, 56%) as a colorless liquid:

8872 J . Org. Chem., Vol. 65, No. 26, 2000
Zhang et al.
Tr is[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis(tr iflu or om eth -
2959, 1601, 1482, 1436, 1237, 1197, 744, 696 cm-1; FABMS
m/z 1447 (M - Cl)+, 1410 (M - 2Cl).
yl)p en tyl)p h en yl]p h osp h a n e (5a ). This was synthesized in
1
a manner similar to 1a : oil; 49% yield; H NMR (300 MHz,
Bis{t r is[4-(3,3,4,4,5,5,5-h ep t a flu or o-2,2-b is(t r iflu or o-
m eth yl)p en tyl)p h en yl]p h osp h in e} P la tin u m Dich lor id e
(14a ). This was synthesized in a manner similar to 13a : 82%
CDCl3) δ 3.54 (s, 6H), 7.33-7.44 (m, 12H); 13C NMR (75 MHz,
CDCl3) δ 32.4, 61.7 (sept, J FC ) 24.1 Hz), 109.6-123.8 (m,
C3F7), 122.1 (q, J FC ) 287.4 Hz), 131.7 (d, J PC ) 5.0 Hz), 132.0,
133.4 (d, J PC ) 19.5 Hz), 137.1 (d, J PC ) 12.0 Hz); 19F NMR
(282.4 MHz, CDCl3) δ -121.9 (6F), -105.0 (6F), -79.2 (9F),
-61.4 (18F); 31P NMR (121.5 MHz, CDCl3) δ -7.12 (s); EIMS
m/z 1258 (M+), 939, 849.
1
yield; mp 238.6-241.2 °C; H NMR (300 MHz, CDCl3) δ 3.50
(s, 12H), 7.13-7.15 (m, 12H), 7.34-7.37 (m, 12H); 13C NMR
(75 MHz, CDCl3) δ 32.2, 60.6-62.0 (m), 104.8-123.2 (m, C3F7),
121.9 (q, J FC ) 289.2 Hz), 128.8, 129.7, 131.1, 134.7; 19F NMR
(282.4 MHz, CDCl3) δ -121.8 (12F), -105.0 (12F), -78.6 (18F),
-60.1 (36F); 31P NMR (121.5 MHz, CDCl3) δ 13.7 (s, J PtP
)
P h en ylbis[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis(tr iflu or o-
m eth yl)p en tyl)p h en yl]p h osp h a n e (5b). This was synthe-
sized in a manner similar to 1a : oil; 68% yield; 1H NMR (300
MHz, CDCl3) δ 3.55 (s, 4H), 7.20-7.39 (m, 13H); 13C NMR (75
MHz, CDCl3) δ 32.5, 61.6 (sept, J FC ) 24.1 Hz), 109.4-123.1
(m, C3F7), 122.0 (q, J FC ) 288.0 Hz), 128.6 (d, J PC ) 6.7 Hz),
129.1, 131.6, 132.0 (d, J PC ) 10.5 Hz), 133.4 (d, J PC ) 19.5
Hz), 133.9 (d, J PC ) 20.0 Hz), 136.4 (d, J PC ) 10.5 Hz), 137.3
(d, J PC ) 11.9 Hz); 19F NMR (282.4 MHz, CDCl3) δ -121.7 (4F),
-104.9 (4F), -78.8 (6F), -61.1 (12F); 31P NMR (121.5 MHz,
CDCl3) δ -6.29 (s); EIMS m/z 926 (M+), 608, 517, 197; HRMS
for C32H17F26P: calcd 926.0653; found 926.0665.
3638 Hz); IR (neat) 2951, 2923, 2866, 1454, 1411, 1333, 1242,
741, 678 cm-1; EIMS m/z 2783 (M+), 2712 (M - 2Cl)+; HRMS
for C78H36F78P2Cl2Pt: calcd 2780.0051, found 2780.0156.
Bis{p h en yl-bis-[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis-tr i-
flu or om eth ylpen tyl) ph en yl]ph osph in e} P latin u m Dich lo-
r id e (14b). This was synthesized in a manner similar to 13a :
1
86% yield; mp 227.4-228.9 °C; H NMR (300 MHz, CDCl3) δ
3.51 (s, 8H), 7.10-7.50 (m, 26H); 13C NMR (75 MHz, CDCl3) δ
32.3, 61.5 (sept, J FC ) 24.8 Hz), 104.8-123.2 (m, C3F7), 121.9
(q, J FC ) 288.4 Hz), 128.0, 128.1, 129.0, 129.9, 131.2, 134.2,
134.4, 134.9; 19F NMR (282.4 MHz, CDCl3) δ -121.9 (8F),
-105.0 (8F), -79.0 (12F), -61.2 (24F); 31P NMR (121.5 MHz,
CDCl3) δ 14.3 (s, J Pt-P ) 3652 Hz); IR (neat) 3060, 2982, 1602,
1565, 1500, 1333, 1245, 1109, 741, 677 cm-1; EIMS m/z 2118
Dip h en yl[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis(tr iflu or o-
m eth yl)p en tyl)p h en yl]p h osp h a n e (5c). This was synthe-
1
sized in a manner similar to 1a : oil; 51% yield; H NMR (300
(M+), 2086 (M
64H34F52P2Cl2Pt: calcd 2116.0309; found 2116.0212.
Gen er a l P r oced u r e for th e Syn th esis of Hom oa llylic
- -
Cl)+, 2047 (M 2Cl)+; HRMS for
MHz, CDCl3) δ 3.59 (s, 2H), 7.26-7.41 (m, 14H); 13C NMR (75
MHz, CDCl3) δ 32.5, 61.6 (sept, J FC ) 24.1 Hz), 105.6-119.8
(m, C3F7), 122.0 (q, J FC ) 288.1 Hz), 128.6 (d, J PC ) 7.0 Hz),
129.0, 131.5 (d, J PC ) 22.3 Hz), 132.1 (d, J PC ) 9.5 Hz), 133.4
C
Alcoh ols. 1-(2,4-Din itr op h en yl)bu t-3-en -1-ol (15a ). A mix-
ture of 2,4-dinitrobenzaldehyde (9.6 mg, 0.049 mmol), fluorous
allytin 6b (92.4 mg, 0.073 mmol), 13a (7.0 mg, 0.0025 mmol),
and BTF (2.5 mL) was stirred at 60 °C for 24 h. After removal
of the solvent, the residue was loaded onto a short column
packed with fluorous reverse-phase silica gel (1.0 g). The
column was eluted with acetonitrile (3 mL) to give 15a (11.7
mg, 100%): 1H NMR (300 MHz, CDCl3) δ 2.34-2.44 (m, 2H),
2.70-2.79 (m, 1H), 5.20-5.28 (m, 1H), 5.47 (dd, J ) 8.3, 3.5
Hz, 1H), 5.83-5.97 (m, 1H), 8.13 (d, J ) 8.7 Hz, 1H), 8.48 (dd,
J ) 8.7, 2.3 Hz, 1H), 8.82 (d, J ) 2.3 Hz, 1H); EIMS m/z 197
(M - C3H5)+, 149, 103.
(d, J PC ) 19.0 Hz), 133.8 (d, J PC ) 19.5 Hz), 136.8 (d, J PC
)
10.5 Hz), 137.6 (d, J PC ) 11.7 Hz); 19F NMR (282.4 MHz,
CDCl3) δ -121.8 (2F), -104.9 (2F), -79.1 (3F), -61.2 (6F); 31
P
NMR (121.5 MHz, CDCl3) δ -5.39 (s); EIMS m/z 594 (M+),
275, 183.
Bis{t r is[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-t r id eca flu or ooct yl)-
p h en yl]p h osp h in e} P la tin u m Dich lor id e (13a ). Platinum
dichloride (50 mg, 0.19 mmol) was heated with 1a (520 mg,
0.40 mmol) under reflux in methylene chloride (4 mL) for 4 h.
The mixture was cooled to room temperature and methylene
chloride (10 mL) was added. After filtration and concentration,
the solid was recrystallized in methylene chloride-ether to
give 13a (460 mg, 85.4%): mp 179.1-180.9 °C; 1H NMR (300
MHz, CDCl3) δ 2.35 (tt, J ) 18.3, 8.7 Hz, 12H), 2.88-2.93 (m,
12H), 7.03 (d, J ) 6.9 Hz, 12H), 7.41 (dd, J ) 11.1, 8.2 Hz,
12H); 13C NMR (125 MHz, CDCl3) δ 26.3, 32.2 (t, J FC ) 22.5
Hz), 108.3-120.0 (m, C6F13), 127.7 (d, J PC ) 67.5 Hz), 127.8,
135.2, 142.3; 19F NMR (282.4 MHz, CDCl3) δ -125.1 (12F),
-122.4 (12F), -121.8 (12F), -120.8 (12F), -113.3 (12F), -79.6
(18F); 31P NMR (121.5 MHz, CDCl3) δ 13.7 (s, J PtP ) 3679 Hz);
IR (neat) 2953, 2917, 2848, 1456, 1204, 1143, 811, 744, 700
cm-1; EIMS m/z 2866 (M+), 2832 (M - Cl)+, 2796 (M - 2Cl)+.
1-(2,4-Dich lor op h en yl)bu t-3-en -1-ol (15b): 1H NMR (300
MHz, CDCl3) δ 2.13-2.58 (m, 2H), 2.59-2.64 (m, 1H), 5.10-
5.22 (m, 3H), 5.78-5.89 (m, 1H), 7.23-7.53 (m, 3H); EIMS m/z
175 (M - C3H5)+, 147, 111.
1-(2-Ch lor o-5-n itr op h en yl)bu t-3-en -1-ol (15c): 1H NMR
(300 MHz, CDCl3) δ 2.30-2.49 (m, 2H), 2.66-2.73 (m, 1H),
5.14-5.33 (m, 2H), 5.80-5.94 (m, 1H), 7.58 (d, J ) 8.8 Hz,
1H), 8.08 (dd, J ) 8.7, 2.7 Hz, 1H), 8.50 (d, J ) 2.6 Hz, 1H);
EIMS m/z 186 (M - C3H5)+, 139, 111.
1-(2-Nitr oph en yl)bu t-3-en -1-ol (15d): 1H NMR (300 MHz,
CDCl3) δ 2.38-2.48 (m, 2H), 2.69-2.75 (m, 1H), 5.19-5.25 (m,
2H), 5.33 (dd, J ) 8.4, 3.6 Hz, 1H), 5.84-5.98 (m, 1H), 7.44
(ddd, J ) 8.3, 8.3, 1.5 Hz, 1H), 7.66 (ddd, J ) 7.4, 7.4, 1.0 Hz,
1H), 7.84 (dd, J ) 7.9, 1.0 Hz, 1H), 7.94 (dd, J ) 8.2, 1.0 Hz,
1H); EIMS m/z 152 (M - C3H5)+, 104, 77.
Bis{P h en ylbis[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr id eca flu or o-
octyl)ph en yl]ph osph in e} P latin u m Dich lor ide (13b). This
was synthesized in a manner similar to 13a : 83% yield; mp
196.8-198.2 °C; 1H NMR (300 MHz, CDCl3) δ 2.35 (tt, J )
1-(2-Tr iflu or om eth ylph en yl)bu t-3-en -1-ol (15e): 1H NMR
(300 MHz, CDCl3) δ 2.18 (br. s, 1H), 2.38-2.45 (m, 1H), 2.51-
2.59 (m, 1H), 5.15-5.24 (m, 3H), 5.83-5.97 (m, 1H), 7.36-
7.41 (m, 1H), 7.57-7.65 (m, 2H), 7.79-7.82 (m, 1H); EIMS m/z
175 (M - C3H5)+, 155, 127.
17.6, 9.0 Hz, 8H), 2.88-2.93 (m, 8H), 7.03-7.47 (m, 26H); 13
C
NMR (75 MHz, CDCl3) δ 26.2, 32.2 (t, J FC ) 21.9 Hz), 110.6-
121.3 (m, C6F13), 127.8 (d, J PC ) 67.3 Hz), 127.4-128.3 (m),
129.2 (d, J PC ) 65.6 Hz), 134.6, 135.3, 142.3; 19F NMR (282.4
MHz, CDCl3) δ -125.0 (8F), -122.4 (8F), -121.8 (8F), -120.8
(8F), -113.3 (8F), -79.6 (12F); 31P NMR (121.5 MHz, CDCl3)
δ 14.2 (s, J PtP ) 3671 Hz); IR (neat) 3058, 2928, 2858, 1601,
1482, 1436, 1198, 744, 696 cm-1; EIMS m/z 2174 (M+), 2103
(M - 2Cl)+.
1-(4-Tr iflu or om eth ylph en yl)bu t-3-en -1-ol (15f): 1H NMR
(300 MHz, CDCl3) δ 2.33-2.61 (m, 3H), 4.80-4.85 (m, 1H),
5.22 (dd, J ) 14.0, 1.1 Hz, 1H), 5.74-5.85 (m, 1H), 7.49 (AB,
J ) 8.2 Hz, 2H), 7.62 (AB, J ) 8.2 Hz, 2H); EIMS m/z 175 (M
- C3H5)+, 127.
Bis{Dip h en yl[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-t r id eca flu or o-
octyl)p h en yl]p h osp h in e} P la tin u m Dich lor id e (13c). This
was synthesized in a manner similar to 13a : 85% yield; mp
230.2-231.6 °C; 1H NMR (300 MHz, CDCl3) δ 2.35 (tt, J )
1-(2-Br om op h en yl)bu t-3-en -1-ol (15g): 1H NMR (300
MHz, CDCl3) δ 2.21 (br. s, 1H), 2.34-2.42 (m, 1H), 2.64-2.70
(m, 1H), 5.10-5.24 (m, 3H), 5.85-5.91 (m, 1H), 7.12-7.17 (m,
1H), 7.33-7.38 (m, 1H), 7.52-7.59 (m, 2H); EIMS m/z 185/
187 (M - C3H5)+, 157/159, 105, 77.
18.0, 9.1 Hz, 4H), 2.88-2.93 (m, 4H), 7.04-7.51 (m, 28H); 13
C
NMR (75 MHz, CDCl3) δ 26.2, 32.3 (t, J FC ) 21.9 Hz), 104.8-
123.2 (m, C6F13), 127.6-129.8 (m), 130.9, 134.7, 135.4, 142.1;
19F NMR (282.4 MHz, CDCl3) δ -125.0 (4F), -122.3 (4F),
-121.7 (4F), -120.7 (4F), -113.3 (8F), -79.7 (6F); 31P NMR
(121.5 MHz, CDCl3) δ 14.7 (s, J PtP ) 3673 Hz); IR (neat) 3060,
1-(3-Br om op h en yl)bu t-3-en -1-ol (15h ): 1H NMR (300
MHz, CDCl3) δ 2.28-2.58 (m, 3H), 4.72 (dd, J ) 7.8, 4.9 Hz,
1H), 5.12-5.22 (m, 2H), 5.73-5.84 (m, 1H), 7.19-7.54 (m, 4H);
EIMS m/z 185/187 (M - C3H5)+, 157/159, 128, 105, 77.

Separation of “Light Fluorous” Reagents and Catalysts
J . Org. Chem., Vol. 65, No. 26, 2000 8873
1-Na p h th a len -1-yl-bu t-3-en -1-ol (15i): 1H NMR (300
MHz, CDCl3) δ 1.74 (br. s, 1H), 2.16-2.21 (m, 2H), 4.93 (dd, J
) 7.4, 5.4 Hz, 1H), 5.17-5.25 (m, 2H), 5.78-5.90 (m, 1H),
7.46-7.87 (m, 7H); EIMS m/z 198 (M+), 157, 129.
NMR (121.5 MHz, CDCl3) δ 30.5 (s); IR (neat) 3058, 2953,
1604, 1438, 1238, 1145, 812, 748, 697 cm-1; EIMS m/z 623 (M
- H)+, 547, 201.
Tr is[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis(tr iflu or om eth -
yl)p en t yl)p h en yl]p h osp h in e oxid e (12a ): 1H NMR (300
MHz, CDCl3) δ 3.59 (s, 6H), 7.42-7.44 (m, 6H), 7.57-7.61 (m,
6H); 13C NMR (75 MHz, CDCl3) δ 32.5, 60.6-62.0 (m), 105.2-
123.2 (m, C3F7), 121.9 (q, J FC ) 288.2 Hz), 131.3, 131.9 (d, J PC
) 9.8 Hz), 132.7, 135.6; 19F NMR (282.4 MHz, CDCl3) δ -122.0
(6F), -104.9 (6F), -79.1 (9F), -61.2 (12F); 31P NMR (121.5
MHz, CDCl3) δ 28.8 (s); IR (neat) 3064, 2956, 2924, 2853, 1605,
1456, 1333, 1260, 1219, 1111, 981, 885, 742, 688 cm-1; FAB-
MS m/z 1273 (M - H)+, 955, 849, 499.
P h en ylbis[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis(tr iflu or o-
m eth yl)p en tyl)p h en yl]p h osp h in e oxid e (12b): 1H NMR
(300 MHz, CDCl3) δ 3.54 (s, 4H), 7.37-7.63 (m, 13H); 13C NMR
(75 MHz, CDCl3) δ 32.4, 61.5 (sept, J FC ) 24.7 Hz), 104.9-
123.0 (m, C3F7), 121.9 (q, J FC ) 288.1 Hz), 128.6 (d, J PC ) 12.1
Hz), 131.0, 131.6-132.4 (m), 133.2, 135.3; 19F NMR (282.4
MHz, CDCl3) δ -121.7 (4F), -105.0 (4F), -79.2 (6F), -61.4
(12F); 31P NMR (121.5 MHz, CDCl3) δ 29.2 (s); IR (neat) 3061,
2972, 1604, 1455, 1332, 1221, 886, 742, 700 cm-1; FAB-MS
m/z 941 (M - H)+, 623, 517.
Dip h en yl[4-(3,3,4,4,5,5,5-h ep ta flu or o-2,2-bis(tr iflu or o-
m eth yl)p en tyl)p h en yl]p h osp h in e oxid e (12c): 1H NMR
(300 MHz, CDCl3) δ 3.56 (s, 2H), 7.27-7.77 (m, 14H); 13C NMR
(75 MHz, CDCl3) δ 32.5, 60.6-62.0 (m), 105.1-119.6 (m, C3F7),
121.9 (q, J FC ) 288.2 Hz), 128.6 (d, J PC ) 12.1 Hz), 131.5-
132.1 (m), 132.8, 133.5, 135.1; 19F NMR (282.4 MHz, CDCl3) δ
-122.0 (2F), -104.9 (2F), -79.1 (3F), -61.2 (6F); 31P NMR
(121.5 MHz, CDCl3) δ 29.8 (s); IR (neat) 3076, 3013, 2974,
1604, 1484, 1439, 1333, 1242, 1119, 886, 750, 702 cm-1; EIMS
m/z 609 (M - H)+, 533, 201.
Tr is[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr id eca flu or ooctyl)p h en -
yl]p h osp h in e Oxid e (11a ). Phosphine 1a (100 mg, 0.077
mmol) was stirred overnight with 3% hydrogen peroxide (0.5
mL). The mixture was extracted with ether (5 mL) three times.
The ether layers were combined, dried over magnesium
sulfate, and concentrated in vacuo. The residue was purified
by column chromatography on silica gel (100% ethyl acetate)
to give 11a (86.4 mg, 86%) as a white solid: mp 63.2-64.0 °C;
1H NMR (300 MHz, CDCl3) δ 2.37 (tt, J ) 18.0, 9.2 Hz, 6H),
2.93-2.98 (m, 6H), 7.27-7.33 (m, 6H), 7.59-7.66 (m, 6H); 13
C
NMR (75 MHz, CDCl3) δ 26.5, 32.5 (t, J FC ) 22.1 Hz), 105.4-
121.3 (m, C6F13), 128.6 (d, J PC ) 12.3 Hz), 131.0 (d, J PC ) 105.1
Hz), 132.6 (d, J PC ) 9.9 Hz), 143.6; 19F NMR (282.4 MHz,
CDCl3) δ -125.4 (6F), -122.6 (6F), -122.0 (6F), -121.0 (6F),
-113.7 (6F), -80.1 (9F); 31P NMR (121.5 MHz, CDCl3) δ 28.8
(s); IR (neat) 3021, 2918, 1849, 1604, 1458, 1238, 1205, 813,
744, 708 cm-1; FAB-MS m/z 1315 (M - H)+, 983, 894, 877,
513.
P h en ylbis[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr idecaflu or ooctyl)-
p h en yl]p h osp h in e Oxid e (11b). This was synthesized in a
manner similar to 11a : oil; 90% yield; 1H NMR (300 MHz,
CDCl3) δ 2.38 (tt, J ) 17.9, 9.1 Hz, 4H), 2.94-3.00 (m, 4H),
7.31-7.70 (m, 13H); 13C NMR (75 MHz, CDCl3) δ 26.5, 32.5
(t, J FC ) 22.1 Hz), 104.8-122.6 (m, C6F13), 128.6 (d, J PC ) 12.1
Hz), 130.1, 131.5, 132.0, 132.1, 132.7 (d, J PC ) 10.0 Hz), 132.9,
143.5; 19F NMR (282.4 MHz, CDCl3) δ -125.1 (4F), -122.4
(4F), -121.8 (4F), -120.8 (4F), -113.6 (4F), -79.8 (6F); 31P
NMR (121.5 MHz, CDCl3) δ 30.1 (s); IR (neat) 3058, 2957,
1604, 1456, 1240, 1145, 812, 747, 710 cm-1; FAB-MS m/z 969
(M - H)+, 623, 531.
Dip h en yl[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tr id eca flu or ooctyl)-
p h en yl]p h osp h in e Oxid e (11c). This was synthesized in a
Ack n ow led gm en t. We thank the National Insti-
tutes of Health for funding this work.
1
manner similar to 11a : oil; 100% yield; H NMR (300 MHz,
CDCl3) δ 2.37 (tt, J ) 18.0, 8.9 Hz, 2H), 2.92-2.98 (m, 2H),
7.30-7.69 (m, 14H); 13C NMR (75 MHz, CDCl3) δ 26.5, 32.5
(t, J FC ) 22.1 Hz), 104.8-122.1 (m, C6F13), 128.6 (d, J PC ) 12.1
Hz), 130.1, 131.6, 132.0, 132.1, 132.7 (d, J PC ) 10.1 Hz), 132.9;
143.4; 19F NMR (282.4 MHz, CDCl3) δ -125.1 (2F), -122.4
(2F), -121.8 (2F), -120.8 (2F), -113.5 (2F), -79.8 (3F); 31P
Su p p or tin g In for m a tion Ava ila ble: copies of 1H and 13C
NMR spectra of all new fluorous phosphines, phosphine oxides,
and complexes.This material is available free of charge via the
Internet at http://pubs.acs.org.
J O000464F