Stereo-and regiospecific syntheses of α- and β-substituted vinyl and dienyl triflones via the stille reaction

Article abstract of DOI:10.1021/ja954303i

Acetylenic anions undergo efficient sulfonylation with trifluoromethanesulfonic anhydride to provide acetylenic triflones. These materials are stereospecifically converted to (Z)-β-iodovinyl triflones in one step via the addition of hydrogen iodide. Access to (Z)-α-iodovinyl trifloaes is also possible via a two-step process involving tributyltin hydride addition to the acetylenic triflones to generate (Z)-α-(tributylstannyl)vmyl triflones followed by an iododestannylation reaction. Both classes of iodovinyl triflones smoothly undergo palladium (O)-mediated Stille reactions with vinyl, aryl, heteroaryl, and acetylenic stannaries to stereospecifically provide trisubstituted vinyl and dienyl triflones.

Full text of DOI:10.1021/ja954303i

4284
J. Am. Chem. Soc. 1996, 118, 4284-4290
Stereo- and Regiospecific Syntheses of R- and â-Substituted
Vinyl and Dienyl Triflones via the Stille Reaction1
Jason S. Xiang, A. Mahadevan, and P. L. Fuchs*
Contribution from the Department of Chemistry, Purdue UniVersity,
West Lafayette, Indiana 47907
ReceiVed December 28, 1995X
Abstract: Acetylenic anions undergo efficient sulfonylation with trifluoromethanesulfonic anhydride to provide
acetylenic triflones. These materials are stereospecifically converted to (Z)-â-iodovinyl triflones in one step via the
addition of hydrogen iodide. Access to (Z)-R-iodovinyl triflones is also possible via a two-step process involving
tributyltin hydride addition to the acetylenic triflones to generate (Z)-R-(tributylstannyl)vinyl triflones followed by
an iododestannylation reaction. Both classes of iodovinyl triflones smoothly undergo palladium (0)-mediated Stille
reactions with vinyl, aryl, heteroaryl, and acetylenic stannanes to stereospecifically provide trisubstituted vinyl and
dienyl triflones.
Introduction
Scheme 1
The seminal contributions of the Hendrickson research group
have established that the trifluoromethyl sulfone (triflone) is
an essentially unique amphoteric functional group; the potent
electron-withdrawing properties of this moiety engender power-
ful polarization of a conjugated olefin toward conjugate-addition
reactions (1 f 2, Scheme 1) as well as subsequently strongly
enhancing the leaving-group ability of the resultant adduct (2
f 3).2,3 Unfortunately, the same inductive effect which renders
the triflone moiety so useful often strongly mitigates against
efficient synthesis where the carbon-sulfur bond is constructed
via nucleophilic protocols.2
In connection with our interest in extending the synthetic
potential of the sulfone moiety, we have recently expanded our
focus to include the synthetic chemistry of trifluoromethyl
sulfones (triflones).4 While we were recently successful at
divising a one-pot Peterson protocol for synthesis of simple vinyl
(7a,b) and dienyl (8a,b) triflones from addition of R-silylated
triflone anion 6 to aldehydes (Scheme 2), all efforts to effect
similar reactions with ketones was thwarted by the poor
nucleophilicity (and steric congestion) of intermediate 6.4b
Faced with the substantial limitations described above, we
decided to explore the potential of transition metal catalyzed
reactions to effect construction of more highly functionalized
vinyl and dienyl triflones (12-15, Scheme 3). This analysis
suggested that â-and R-iodovinyl triflones 10 and 11 would
constitute ideal substrates in Stille reactions with a variety of
vinyl, aryl, and acetylenic stannane reagents.
acetylenic anion.5 This approach is partially compromised by
the tendency of the intermediate acetylenic triflone to undergo
subsequent chemistry under the conditions of its formation.
Fortunately, we have found that inVerse addition minimizes the
formation of diacetylenes as well as other unwanted polycon-
densation products. For example, model acetylenic triflones
9a,b can be prepared in 75-87% yield by this simple modifica-
tion. While acetylenic triflones have seen relatively little use
in organic synthesis,4d,5 we find that lithium iodide in acetic
acid6 effects stereo- and regiospecific addition to acetylenic
triflones 9a and 9b to provide excellent yields of â-iodovinyl
triflones Z-10a and Z-10b, respectively (Scheme 4). Testament
to the inductive effect of the triflone moiety is the finding that
the HI addition reaction occurs within minutes at 0 °C as
compared to the same reaction with acetylenic esters, which
require 12 h at 70 °C.6 Perhaps even more amazing is the
observation that aqueous lithium iodide, in the absence of any
acid catalysis, will also afford â-iodovinyl triflones 10a,b albeit
in substantially reduced yields (∼40%).
Unambiguous definition of the olefin geometry of Z-10a,b
required the preparation of the isomeric trisubstituted vinyl
triflone E-10a,b. This was accomplished by photolysis of Z-10a
at 254 nm for 2 h in deuterated acetonitrile at 30 °C using a
Rayonet reactor. The resultant photostationary equilibrium
consisted of 60% Z-10a and 40% of E-10a, which were
separated by chromatography. Similar photolysis of Z-10b
resulted in conversion to a mixture of E-10b and acetylenic
triflone 9b. Chromatography of the mixture easily provided a
pure sample of E-10b. The indicated structural assignments
were principally the result of a pair of equilibrium NOE
experiments.7 The first of these experiments involved irradiation
Results and Discussion
Acetylenic triflones have traditionally been prepared in 50-
70% yield by addition of triflic anhydride to a solution of an
X Abstract published in AdVance ACS Abstracts, March 15, 1996.
(1) Syntheses via Vinyl Sulfones. 62. Triflone Chemistry. 4. For previous
triflone papers: see footnote 4c.
(2) For excellent reviews discussing the chemistry of triflones, see: (a)
Hendrickson, J. B.; Sternbach, D. D.; Bair, K. W. Acc. Chem. Res. 1977,
10, 306. (b) Hendrickson, J. B.; Bair, K. W.; Bergeron, R.; Giga, A.; Skipper,
P. L.; Sternbach, D. D.; Wareing, J. Org. Prep. Proced. Int. 1977, 9, 173.
(c) Hendrickson, J. B.; Judelson, D. A.; Chancellor, T. Synthesis 1984, 320.
(3) Cumyl triflone undergoes solvolysis 170 times more slowly than
cumyl chloride but 107 times more rapidly than cumyl phenyl sulfone:
Creary, X. J. Org. Chem. 1985, 50, 5080.
(5) (a) Glass, R. S.; Smith, D. L. J. Org. Chem. 1974, 39, 3712. (b)
Berk, H. C.; Franz, J. E. Synth. Commun. 1981, 11, 267. (c) Massa, F.;
Hanack, M.; Subramanian, L. R. J. Fluorine Chem. 1982, 601. (d) Hanack.
M.; Subramanian, L. R. Synthesis 1988, 592. (e) Hanack, M.; Willhelm, B.
Angew. Chem., Int. Ed. Engl. 1989, 28, 1057.
(6) (a) Ma, S.; Lu, X. J. Chem. Soc., Chem. Commun. 1990, 1643. (b)
Marek, I.; Alexakis, A.; Normant, J.-F. Tetrahedron Lett. 1991, 32, 5329.
(c) Lu, X.; Huang, X.; Ma, S. Tetrahedron Lett. 1992, 33, 2535. (d) Meyer,
C.; Marek, I.; Normant, J. -F. Synlett 1993, 386.
(4) (a) Magar, S. S.; Fuchs, P. L. Tetrahedron Lett. 1992, 33, 745. (b)
Mahadevan, A.; Fuchs. P. L. Tetrahedron Lett 1994, 35, 6025. (c)
Mahadevan, A.; Fuchs, P. L. J. Am. Chem. Soc. 1995, 117, 3272.
S0002-7863(95)04303-4 CCC: $12.00 © 1996 American Chemical Society

R- and â-Substituted Vinyl and Dienyl Triflones
J. Am. Chem. Soc., Vol. 118, No. 18, 1996 4285
Scheme 2
Scheme 3
Scheme 4
Scheme 5
of the allylic methylene group for both isomers of the octynyl
triflones with observation of the enhancement of the vinyl proton
HR. The finding of 23% and 6% enhancement for Z-10a and
E-10a is uniquely consistent with the assigned stereochemistry
of the olefin isomers (Scheme 5; Table 1). Delineation of the
â-phenylvinyl triflones Z-10b and E-10b involved irradiation
of the vinylic hydrogen and observation of the NOE for the
o-aryl hydrogens. In this instance the Z isomer showed 4.5%
enhancement, while the E isomer revealed no interaction
(Scheme 5; Table 1).
Table 1. NMR Data for 10a and 10b Z and E Isomers
observable
Z-10a E-10a Z-10b E-10b
1H chemical shift HR (δ)
6.9
3.6
7.0
3.3
42
3.05
6
20
7.15
7.25
width at half-height HR (Hz)
13C chemical shift allylic CH2 (δ) 50
1H chemical shift allylic CH2 (δ)
equilibrium NOEa (%)
2.88
23
8
4.5
7
none
5.5
relaxation time τ1 (s)
a The allylic CH2 was irradiated with observation of the vinylic HR
for Z,E-10a; the vinylic HR was irradiated with observation of the o-aryl
hydrogens for Z,E-10b.
Stille coupling8 of â-iodovinyl triflones Z-10a and E-10a with
vinyl tributylstannane 16 in the presence of a catalytic amount
of tetrakis(triphenylphosphine)palladium(0) (17) stereospecifi-
cally provides trisubstituted dienyltriflones Z-12a and E-12a
in high yield (Scheme 6).
â-iodovinyl triflones Z-10a and Z-10b as substrates. These
reactions smoothly provided the trisubstituted unsaturated
triflones 12b-f and 13a,b,f as detailed in Table 2.
While most of the examples in Table 2 are straightforward,
the reaction of Z-10a with trans-1,2-distannylethylene 19 merits
further discussion. The reaction of these two compounds is very
poor using tetrakis(triphenylphosphine)palladium(0) 17 (Table
2, entries 2.2, 2.1), but using 1.7 equiv of distannylethylene 19
in the presence of bis(benzonitrile)palladium dichloride provides
a 70% yield of δ-stannyldienyl triflone 12c in addition to 20%
of the expected bis coupling product 20 (Table 2, entry 2.3
A variety of stannane reagents were surveyed in the pal-
ladium-mediated Stille reaction using the now readily available
(7) Derome, A. E. Modern NMR Techniques for Chemistry Research;
Pergamon Press, New York, 1987; pp 121-122.
(8) (a) Reviews: Mitchell, T. N. Synthesis 1992, 803. Stille, J. K. Angew.
Chem., Int. Ed. Engl. 1986, 25, 508. (b) Stille, J. K.; Simpson, J. H. J. Am.
Chem. Soc. 1987, 109, 2138. (c) Stille, J. K.; Groh, B. L. J. Am. Chem.
Soc. 1987, 109, 813.

4286 J. Am. Chem. Soc., Vol. 118, No. 18, 1996
Xiang et al.
Scheme 6
Table 2. Stille Coupling Reactions of â-Iodovinyl triflones
Scheme 7). This allows for the possibility of construction of
even more complex dienyl triflones. For example, subsequent
palladium-catalyzed reaction of 12c with iodobenzene affords
δ-phenyldienyl triflone 26 in 91% yield (Scheme 7).

R- and â-Substituted Vinyl and Dienyl Triflones
J. Am. Chem. Soc., Vol. 118, No. 18, 1996 4287
Scheme 7
Scheme 8
Attention was next directed to the synthesis of trisubstituted
R-iodovinyl triflones 14 and 15. These compounds cannot be
prepared by classical olefination methods such as the Peterson
olefination or the Wadsworth-Emmons reaction. Because of
the success enjoyed in the synthesis of 12 and 13, we were
drawn to consider palladium-catalyzed hydrostannylation of
acetylenes 9a,b, a reaction which had been shown to proceed
with excellent regio- and stereoselectivity, and good overall
yields in the case of other polarized acetylenic substrates.9 In
the event, hydrostannylation of acetylenic triflone 9a with
tributyltin hydride in the presence of tetrakis(triphenylphos-
phine)palladium(0) (17) rapidly provided R-stannylated vinyl
triflones E-27a and Z-27a regiospecifically, but the reaction
was not stereospecific, affording a 1:1.7 ratio of E and Z
stereoisomers. Attempts were made to improve the stereospeci-
ficity of the palladium-catalyzed hydrostannylation reaction by
using the more sterically demanding triphenyltin hydride.
Surprisingly, this modification served to reverse the stereo-
chemical ratio (E-27b/Z-27b ) 1.5:1); nevertheless, it was clear
that a better protocol was needed. Fortunately, it was found
that simply allowing neat tributyltin hydride to react with the
acetylenic triflone 9a for 1 h at 25 °C stereospecifically produced
Z-27a in 98% yield. Repeating the process with triphenyltin
hydride also stereospecifically afforded the triphenylstannyl
analog Z-27b in 95% yield (Scheme 8).
dichloride (25) were unavailing. Therefore, Z-27a was reacted
with iodine in dichloromethane at 25 °C to provide an 88%
yield of R-iodovinyl triflone 11a. By way of contrast, R-io-
dovinyl triflone 11a undergoes efficient Stille reaction with
vinyltributylstannane (16) and 2-furylstannane 24 to afford
cross-conjugated dienyl triflone E-14a and trisubstituted vinyl
triflone E-14f, respectively (Scheme 9).
Experimental Section
Starting materials were obtained either from Aldrich Chemicals or
from other commercial suppliers. Solvents were purified as follows:
diethyl ether and tetrahydrofuran, by distillation from benzophenone
ketyl under argon; methylene chloride, benzene, and toluene, by
distillation from calcium hydride.
1H NMR (300 and 200 MHz) and 13C NMR (75 and 50 MHz) spectra
were recorded on General Electric QE-300 and Varian Gemini 200
instruments, respectively. 1H chemical shifts are reported in parts per
million (ppm) from the internal chloroform (7.26 ppm); TMS (0 ppm);
or benzene (7.15 ppm) standard. Coupling constants (J ) are reported
in hertz. 13C chemical shifts are reported in parts per million relative
to chloroform (77 ppm); 19F NMR (283 MHz) spectra were recorded
on a General Electric QE-300 instrument. 19F chemical shifts are
reported in parts per million relative to CFCl3 (0 ppm) standard.
Melting points reported are uncorrected and were obtained on a Mel-
Temp apparatus. Low-resolution EI and CI mass spectra were obtained
on a Finnigan 400 mass spectrometer. High-resolution mass spectra
(HRMS) were obtained on a Kratos MS-50 instrument.
Assignment of stereochemistry for these trisubstituted R-stan-
nylvinyl triflones was readily accomplished by proton NMR
based upon the three-bond coupling between the tin atom and
the terminal vinyl hydrogen. Specifically it was found that
E-27a,b exhibited 3JSn-H values of 42 and 55 Hz, while Z-27a,b
had coupling constants of 67 and 90 Hz, respectively.10
All reactions described were carried out under an atmosphere of
argon unless otherwise indicated. All yields reported are isolated yields
of material. TLC was performd on Merck glass silica gel plates.
Column chromatography was performed using Merck silica gel 60 (60-
200 mesh).
Attempts at direct coupling of R-stannylvinyl triflone Z-27a
with iodobenzene or vinyl iodide 2811 using tetrakis(triph-
enylphosphine)palladium(0) (17) or bis(acetonitrile)palladium
(10) (a) Delmas, M; Maire, J. C.; Santamaria, J. J. Organomet. Chem.
1969, 16, 405. (b) Mitchell, T. N.; Amamria, A.; Killing, H.; Rutschow, D.
J. Organomet. Chem. 1983, 241, C45. (c) Chenard, B. L.; Van Zyl, C. M.
J. Org. Chem. 1986, 51, 3561. (d) Cochran, J. C.; Williams, L. E.; Bronk,
B. S.; Calhoun, J. A.; Fassberg, J.; Clark, K. G. Organometallics 1989, 8,
804.
(9) (a) Cochran, J. C.; Bronk, B. S.; Terrence, K. M.; Phillips, H. K.
Tetrahedron Lett. 1990, 31, 6621. (b) Rossi, R.; Carpita, A.; Cossi, P.
Tetrahedron Lett. 1992, 33, 4495.
(11) Donaldson, R. E.; Fuchs, P. L. J. Am. Chem. Soc. 1981, 103, 2108.

4288 J. Am. Chem. Soc., Vol. 118, No. 18, 1996
Xiang et al.
Scheme 9
1-Octynyl Trifluoromethyl Sulfone (9a). 1-Octyne (0.500 g, 4.5
mmol) was added dropwise to a stirred solution of n-BuLi (4.8 mmol,
2 mL, 2.4 M in hexane) in diethyl ether (50 mL) at -78 °C. The
reaction mixture was stirred at -78 °C for 1 h followed by slow cannula
transfer of the lithium acetylide to a solution of triflic anhydride (1.280
g, 4.5 mmol) in 20 mL of ether at -78 °C. After the addition, the
temperature was maintained at -78 °C for 30 min and then slowly
warmed to 0 °C, and the reaction mixture was quenched with water.
The aqueous layer was extracted with ether, and the combined organic
extracts were washed with brine. Drying and concentration afforded
a yellow oil, which was purified by column chromatography (silica
gel deactivated with acetone, pentane eluent) to yield 0.95 g (87%) of
pure 1-octynyl trifluoromethyl sulfone 9a as a colorless oil (Rf 0.50,
SiO2, 0.05:1 EtOAc/hexane): 1H NMR (300 MHz, CDCl3) δ 2.55 (t,
7.0 Hz, 2H), 1.66 (m, 2H), 1.38 (m, 6H), 0.90 (t, 6.6 Hz, 3H); 13C
NMR (75 MHz, CDCl3) δ 13.81, 19.19, 22.29, 26.48, 28.31, 30.92, ,
70.19, 105.93, 118.84 (q, JC,F ) 323 Hz); 19F NMR (283 MHz, CFCl3)
δ -81.6; mass spectrum (CI), 243 (M + H+, 1.00), 109 (0.09); HRMS
calcd for C9H14F3O2S 243.0667, found 243.0667.
oil in 85% yield (Rf 0.35, SiO2, 0.05:1 EtOAc/hexane): 1H NMR (200
MHz, CDCl3) δ 7.14 (s, 1H), 7.42-7.59 (m, 5H); 13C NMR (50 MHz,
CDCl3) δ 119.69(q, JC,F ) 327 Hz), 127.39, 128.43, 129.29, 129.49,
132.69, 142.23; mass spectrum (EI), 362 (0.01), 235 (0.42), 105 (0.52),
102 (1.00); mass spectrum (CI), 363 (1.00), 235 (0.10); HRMS calcd
for C9H6F3IO2S 361.9085, found 361.9081.
(E)-2-Iodo-1-[(trifluoromethyl)sulfonyl]oct-1-ene (E-10a). Ac-
etonitrile was purged with argon for 15 min before use. Vinyl iodide
Z-10a (0.230 g, 0.62 mmol) dissolved in acetonitrile (5 mL) was added
into a quartz tube under argon. The reaction mixture was irradiated
with 254 nm ultraviolet light in a Rayonet reactor for 2 h. The mixture
was then partitioned between pentane and water. Usual work-up and
column chromatography afforded 0.092 g (40%) of E-10a as a colorless
oil (Rf 0.45, SiO2, 0.05:1 EtOAc/hexane) in addition to 43% recovered
Z-10a. In a separate experiment monitored by NMR, it was found
that longer exposure time to UV led to the formation of significant
amounts of side products. E-10a: 1H NMR (200 MHz) δ 0.91 (m,
3H), 1.37 (m, 6H), 1.66 (m, 2H), 3.09 (t, 7.5 Hz, 2H), 7.01 (s, 1H);
13C NMR (50 MHz) δ 14.47, 22.90, 28.59, 31.02, 31.83, 41.75, 119.97
(q, JC,F ) 326 Hz), 128.92, 141.00; mass spectrum (EI), 237 (0.01),
236 (0.01), 173 (0.02), 167 (0.08), 109 (M - SO2CF3 - HI, 0.97);
mass spectrum (CI), 371 (M + H+, base peak), 212 (0.17); HRMS
calcd for C9H15F3IO2S 370.9790, found 370.9786.
(Z)-1-Iodo-1-phenyl-2-[(trifluoromethyl)sulfonyl]ethene (E-10b).
This vinyl iodide was prepared from Z-10b, using a procedure similar
to that described for E-10a. The reaction was complete within 1 h.
Product E-10b was obtained as a yellow oil in 72% yield (Rf 0.40,
SiO2, 0.05:1 EtOAc/hexane): 1H NMR (200 MHz) δ 7.27(s, 1H),
7.35-7.44 (m, 5H); 13C NMR (50 MHz) δ 119.64 (q, JC,F ) 333 Hz),
127.76, 128.44, 128.59, 129.42, 131.43, 134.27, 139.52; mass spectrum
(CI), 363 (M + H+, base peak); HRMS calcd for C9H6F3IO2S 361.9085,
found 361.9090.
(Z)-1-Iodo-1-[(trifluoromethyl)sulfonyl]oct-1-ene (Z-11a). To a
stirred solution of vinylstannane Z-27a (0.455 g, 0.85 mmol) in 10
mL of CH2Cl2 was added I2 (0.217 g, 0.85 mmol) at 25 °C. After
stirring for 2 h, an additional amount of I2 (0.087 g, 0.34 mmol) was
added and the resulting solution was stirred overnight. Reaction was
complete as determined by TLC (SiO2, 0.05:1 EtOAc/hexane). The
resulting solution was diluted with CH2Cl2, washed with Na2S2O3
(aqueous) and brine, dried (MgSO4), and concentrated in Vacuo. The
crude mixture was purified by column chromatography (silica gel,
pentane) to afford Z-11a (0.262 g, 88%) as a yellow oil (Rf 0.50, SiO2,
0.05:1 EtOAc/hexane): 1H NMR (300 MHz, CDCl3) δ 0.91 (m, 3H),
1.30 (m, 6H), 1.58 (m, 2H), 2.42 (q, 7.2 Hz, 2H), 7.59 (t, 7.2 Hz,
1H); 13C NMR (50 MHz, CDCl3) δ 14.45, 22.92, 27.40, 29.28, 31.88,
37.76, 88.53, 120.02 (q, JC,F ) 327 Hz), 165.39; mass spectrum (CI),
371 (M + H+, base peak); HRMS calcd for C9H15F3IO2S 370.9790,
found 370.9786.
Phenylethynyl Trifluoromethyl Sulfone (9b). This triflone was
prepared from phenylacetylene, using a procedure similar to that
described above. Product 9b was obtained as a yellow solid in 75%
yield (Rf 0.40, SiO2, 0.05:1 ether/hexane): mp 29.0-31.5 °C (hexane);
1H NMR (300 MHz, CDCl3) δ 7.35-7.76 (m, 5H); 13C NMR (75 MHz,
CDCl3) δ 77.6, 101.3, 116.1, 119.4 (q, JC,F ) 322 Hz), 129.4, 133.8,
134.1; 19F NMR (283 MHz, CFCl3) δ -81.1; mass spectrum (EI), 234
(0.25), 165 (0.97), 89 (1.00); mass spectrum (CI), 235 (M + H+, 0.99);
1
HRMS calcd for C9H5F3SO2 233.9962, found 233.9969. The H and
13C NMR are consistent with those reported.5d
(Z)-2-Iodo-1-[(trifluoromethyl)sulfonyl]oct-1-ene (Z-10a). To a
solution of octynyl trifluoromethyl sulfone 9a (0.570 g, 2.35 mmol) in
10 mL of THF at 0 °C was added lithium iodide (0.330 g, 2.47 mmol,
1.05 equiv) followed by glacial acetic acid (0.14 mL, 2.35 mmol, 1
equiv). The reaction was complete within 15 min. THF was removed
in Vacuo, and the residue was partitioned between ether and water.
The organic layer was dried (MgSO4), filtered, and concentrated. The
resulting yellow oil was purified by column chromatography (silica
gel deactivated with acetone, eluted with 2% ether/pentane) to afford
0.808 g (93%) of 10a as a colorless oil (Rf 0.40, SiO2, 0.05:1 EtOAc/
hexane): 1H NMR (300 MHz, CDCl3) δ 0.90 (t, 4.7 Hz, 3H), 1.31 (m,
6H), 1.65 (m, 2H), 2.87(t, 7.1 Hz, 2H), 6.88 (s, 1H); 13C NMR (75
MHz, CDCl3) δ 13.85, 22.34, 27.62, 29.15, 31.21, 49.62, 119.04 (q,
JC,F ) 325 Hz), 125.86, 133.92; 19F NMR (283 MHz, CFCl3) δ -76.8;
mass spectrum (EI), 371(0.14), 167(0.26), 109(1.00) ; mass spectrum
(CI), 371(M + H+, base peak); HRMS calcd for C9H15F3IO2S 370.9790,
found 370.9779.
(Z)-1-Iodo-1-phenyl-2-[(trifluoromethyl)sulfonyl]ethene (Z-10b).
This vinyl triflone was prepared from phenylethynyl trifluoromethyl
sulfone, using a procedure similar to that described above. The reaction
was complete within 45 min. Product Z-10b was obtained as a yellow
2-n-Hexyl-(Z)-1,3-butadienyl Trifluoromethyl Sulfone (Z-12a).
Toluene was purged with argon for 15 min before use. To a solution

R- and â-Substituted Vinyl and Dienyl Triflones
J. Am. Chem. Soc., Vol. 118, No. 18, 1996 4289
of â-iodovinyl triflone Z-10a (0.660 g, 1.78 mmol) in 10 mL of toluene
was added tetrakis(triphenylphosphine)palladium (17) (Aldrich, 0.103
g, 0.09 mmol, 5 mol %) under argon. Vinyltributyltin (Aldrich, 0.564
g, 1.78 mmol, 1 equiv) was added via syringe, and the solution was
heated to reflux. The reaction was complete within 2 h as determined
by TLC (SiO2, 1:10 EtOAc/hexane). The reaction mixture was cooled
to room temperature and washed with water. The aqueous layer was
extracted with ether. The extracts were combined, washed with brine,
dried (MgSO4), and concentrated in Vacuo. The residue was purified
by column chromatography (silica gel deactivated with acetone, eluted
with 2% ether/pentane) to afford 0.451 g (94%) of Z-12a as a colorless
oil (Rf 0.35, SiO2, 1:10 EtOAc/hexane): 1H NMR (200 MHz, CDCl3)
δ 0.9 (t, 6.7 Hz, 3H), 1.33 (m, 6H), 1.55 (m, 2H), 2.56 (t, 7.6 Hz, 2H),
5.75 (d, 11.1 Hz, 1H), 5.89 (d, 17.1 Hz, 1H), 6.03 (s, 1H), 7.46 (dd,
11.1 Hz, 17.4 Hz, 1H) . 13C NMR (75 MHz, CDCl3) δ 13.94, 22.45,
28.85, 28.89, 31.37, 34.24, 115.83, 119.92 (q, JC,F ) 324 Hz), 126.03,
129.68, 164.97; 19F NMR (283 MHz, CFCl3) -80.8 δ; mass spectrum
(EI), 271 (0.49), 137 (0.07), 107 (0.13), 67 (1.00); mass spectrum (CI),
271 (M + H+, base peak); HRMS calcd for C11H17F3O2S 271.0980,
found 271.0974.
1.57 (m, 4H), 2.58 (t, 7.6 Hz, 4H), 6.24 (s, 2H), 7.92 (s, 2H); 13C NMR
(50 MHz, CDCl3) δ 14.44, 22.91, 29.33, 29.48, 31.81, 35.47, 120.20,
120.29 (q, JC,F ) 326 Hz), 131.21, 163.85; mass spectrum (EI), 443
(0.08), 205 (0.16), 175 (0.47),121 (0.25); mass spectrum (CI), 513 (M
+ H+, base peak); HRMS calcd for C20H31F6O4S2 513.1568, found
513.1563.
(Z)-3-n-Hexyl-1-(trimethylsilyl)-4-[(trifluoromethyl)sulfonyl]but-
3-en-1-yne (12d). To a solution of â-iodovinyl triflone 10a (0.107 g,
0.29 mmol) in benzene (4 mL) was added tetrakis(triphenylphosphine)-
palladium (17) (Aldrich, 0.017 g , 0.014 mmol, 5 mol %) under argon.
1-(Tributylstannyl)-2-(trimethylsilyl)ethyne (22)14 (0.123 g, 0.32 mmol)
was added slowly via syringe, and the resulting solution was stirred at
50 °C under argon for 9 h. Analysis by TLC (SiO2, 0.05:1 EtOAc/
hexane) indicated that the reaction was complete. Usual workup and
column chromatography (silica gel deactivated with acetone, pentane
eluent) afforded 12d (0.075 g, 77%) as a colorless oil (Rf 0.60, SiO2,
0.05:1 ether/hexane): 1H NMR (200 MHz, CDCl3) δ 0.25 (s, 9H), 0.90
(m, 3H), 1.30 (m, 6H), 1.64 (m, 2H), 2.41 (t, 7.5 Hz, 2H), 6.32 (s,
1H); 13C NMR (50 MHz, CDCl3) δ 0, 14.44, 22.89, 28.02, 28.71, 31.81,
40.16, 98.24, 116.89, 120.54 (q, JC,F ) 327 Hz), 123.53, 151.25; mass
spectrum (EI), 341 (0.02), 325 (0.41), 77 (1.00), 73 (0.93), mass
spectrum (CI), 341 (M + H+, base peak); HRMS calcd for C14H24F3O2-
SSi 341.1218, found 341.1211.
(Z)-2-n-Hexyl-2-phenyl-1-[(trifluoromethyl)sulfonyl]ethene (12e).
To a solution of â-iodovinyl triflone 10a (0.170 g, 0.459 mmol) in 4
mL of benzene was added tetrakis(triphenylphosphine)palladium (17)
(Aldrich, 0.028 g, 0.025 mmol, 5 mol %) under argon. Phenyltribu-
tylstannane (23) (Aldrich, 0.185 g , 0.505 mmol, 1.1 equiv) was added
via syringe, and the solution was heated to reflux. The reaction was
complete within 3 h. Usual workup and column chromatography (silica
gel deactivated with acetone, eluted with 5% ether/pentane) afforded
12e (0.117 g, 80%) as a colorless oil (Rf 0.25, SiO2, 0.05 ether/
hexane): 1H NMR (200 MHz, CDCl3) 7.40 (m,3H), 7.20 (m, 2H), 6.31
(s, 1H), 2.60 (t, 6.8 Hz, 2H), 1.26∼1.54 (m, 8H), 0.88 (t, 6.6 Hz, 3H);
13C NMR (50 MHz, CDCl3) δ 14.46, 22.94, 27.35, 29.00, 31.86, 42.73,
120.14 (q, JC,F ) 326 Hz), 116.90, 127.45, 128.46, 129.78; mass
spectrum (EI), 251 (0.02), 250 (0.17), 128 (0.07), 117 (1.00); mass
spectrum (CI), 321 (M + H+, base peak); HRMS calcd for C15H20F3-
SO2 321.1136, found 321.1139.
(Z)-2-n-Hexyl-2-(2-furyl)-1-[(trifluoromethyl)sulfonyl]ethene (12f).
To a solution of â-iodovinyl triflone 10a (0.105 g, 0.28 mmol) in 3
mL of benzene was added tetrakis(triphenylphosphine)palladium (17)
(Aldrich, 0.016 g, 0.014 mmol, 5 mol %) under argon. 2-Furyltribu-
tylstannane (24) (Aldrich, 0.106 g, 0.298 mmol, 1.05 equiv) was injected
with a syringe, and the solution was heated to reflux. The reaction
was complete within 2 h. Usual workup and column chromatography
(silica gel deactivated with acetone, eluted with 5% ether/pentane)
afforded 12f (0.075 g, 85%) as a colorless oil (Rf 0.30, SiO2, 0.05
ether/hexane): 1H NMR (200 MHz, CDCl3) δ 7.64 (d, 1.71 Hz, 1H),
7.23 (d, 3.67 Hz, 1H), 6.57 (dd, 1.83 Hz, 3.67 Hz, 1H), 6.01 (s, 1H),
2.68 (t, 7.55 Hz, 2H), 1.58 (m, 2H), 1.32 (m, 6H), 0.89 (t, 6.45 Hz,
3H); 13C NMR (50 MHz, CDCl3) δ 14.45, 22.94, 29.21, 29.72, 31.86,
37.90, 112.47, 113.25, 119.33, 120.59 (q, JC,F ) 327 Hz), 146.66,
148.12, 153.46; mass spectrum (EI), 311 (0.01), 310 (0.01), 240 (0.48),
107 (1.00), (CI), 311 (M + H+, base peak); HRMS calcd for C13H17F3-
SO3 311.0929, found 311.0920.
2-n-Hexyl-(E)-1,3-butadienyl Trifluoromethyl Sulfone (E-12a).
This dienyl triflone was prepared from vinyl iodide E-10a, using a
procedure similar to that described for Z-12a. The product E-12a was
obtained as a yellow oil in 95% yield (Rf 0.45, SiO2, 1:10 EtOAc/
hexane): 1H NMR (200 MHz, CDCl3) δ 0.92 (m, 3H), 1.42 (m, 8H),
2.80 (t, 7.80 Hz, 2H), 5.69 (d, 10.62 Hz, 1H), 5.90 (d, 17.22 Hz, 1H),
6.10 (s, 1H), 6.36 (dd, 10.62 Hz, 17.36 Hz, 1H). 13C NMR (50 MHz,
CDCl3) δ 14.57, 22.83, 28.10, 30.07, 31.14, 31.96, 117.83, 120.03 (q,
JC,F ) 330 Hz), 125.29, 136.81, 167.00; mass spectrum (CI), 271 (M
+ H+, base peak); HRMS calcd for C11H18F3O2S 271.0980, found
271.0983.
(1Z,3E)-2-n-Hexyl-4-(trimethylsilyl)-1,3-butadienyl Trifluorom-
ethyl Sulfone (12b). To a solution of â-iodovinyl triflone 10a (0.056
g, 0.15 mmol) in 2 mL of benzene was added tetrakis(triphenylphos-
phine)palladium (17) (Aldrich, 0.09 g, 5 mol %) under argon. (E)-1-
(Tributylstannyl)-2-(trimetylsilyl)ethylene (18)12 (0.065 g, 0.17 mmol)
was slowly added via syringe to the above solution, and the mixture
was heated to reflux. The reaction was complete within 2 h. Usual
workup and column chromatography (silical gel deactivated with
acetone, pentane eluent) afforded 0.042 g (81%) of 12b as a yellow
oil (Rf 0.65, SiO2, 0.05:1 EtOAc/hexane): 1H NMR (200 MHz, CDCl3)
δ 0.17 (s, 9H), 0.89 (m, 3H), 1.33 (m, 6H), 1.52 (m, 2H), 2.52 (t, 7.3
Hz, 2H), 6.02 (s, 1H), 6.70 (d, 19.0 Hz, 1H), 7.62 (d, 18.8 Hz, 1H);
13C NMR (50 MHz, CDCl3) δ - 1.31, 14.47, 22.96, 29.38, 30.21, 31.88,
34.69, 115.65, 120.51 (q, JC,F ) 326 Hz), 136.12, 145.80, 165.91; mass
spectrum (EI), 343 (0.03), 327 (0.19), 277 (0.10), 191 (0.19), 141 (0.93);
mass spectrum (CI), 343 (M + H+, base peak); HRMS calcd for
C14H26F3O2SSi 343.1375, found 343.1368.
(1Z,3E)-2-n-Hexyl-4-(tributylstannyl)-1,3-butadienyl Trifluorom-
ethyl Sulfone (12c). â-Iodovinyl triflone 10a (0.02 g, 0.054 mmol)
in 0.5 mL of CDCl3 was added to a solution of (E)-1,2-bis-
(tributylstannyl)ethylene (19)13 (0.055 g, 0.092 mmol, 1.7 equiv) and
solid Pd(PhCN)2Cl2 (Aldrich, 0.01 g, 0.003 mmol, 5 mol %) in 1 mL
of dry CDCl3. The solution turned brown immediately. The reaction
1
was complete within 3 h at 25 °C as monitored by H NMR. After
removal of solvent in Vacuo, the residue was purified by column
chromatography (silica gel deactivated with acetone, 5% ether/pentane)
to afford 0.021 g (70%) of 12c as a colorless oil (Rf 0.50, SiO2, 0.05:1
EtOAc/hexane): 1H NMR (200 MHz, CDCl3) δ 0.90 (m, 18H), 1.32
(m, 12H), 1.53 (m, 8H), 2.51 (t, 7.4 Hz, 2H), 5.96 (s, 1H), 7.26 (d,
19.4 Hz, 1H), 7.66 (d, 19.3 Hz, 1H); 13C NMR (50 MHz, CDCl3) δ
10.29, 14.08, 14.43, 22.94, 27.70, 29.36, 29.48, 29.69, 31.92, 34.57,
114.18, 120.59 (q, JC,F ) 326 Hz), 138.57, 149.61, 165.37; mass
spectrum (EI), 503 (0.71), 369 (0.22), 313 (0.55), 253 (0.32), 177 (0.23);
mass spectrum (CI), 561 (M + H+, 0.03), 503 (M + H+ - C4H9, 1.00);
HRMS calcd for C19H34F3O2S116Sn 499.1249, found 499.1254.
2-Phenyl-(E)-1,3-butadienyl Trifluoromethyl Sulfone (13a). Ben-
zene was purged with argon for 15 min before use. To a solution of
â-iodovinyl triflone Z-10b (0.05 g, 0.138 mmol) in 5 mL of benzene
was added tetrakis(triphenylphosphine)palladium (17) (Aldrich, 0.08
g, 5 mol %) under argon. Vinyltributyltin (Aldrich, 0.048 g, 0.152
mmol) was added via syringe, and the solution was heat to reflux. The
reaction was complete within 3 h. Usual workup and column
chromatography (silica gel deactivated with acetone, eluted with 5%
ether/hexane) afforded 13a (0.029 g, 81%) as a colorless oil (Rf 0.40,
SiO2, 0.05:1 EtOAc/hexane): 1H NMR (200 MHz, CDCl3) δ 5.57 (d,
17.3 Hz, 1H), 5.94 (d, 10.74 Hz, 1H), 6.14 (s, 1H), 7.32-7.52 (m,
5H), 7.71 (dd, 17.1, 10.8 Hz, 1H); 13C NMR (50 MHz, CDCl3) δ
116.44, 120.6 (q, JC,F ) 322 Hz), 129.22, 129.44, 131.09, 131.31,
132.31, 137.18, 164.56. Mass Spectrum (CI), 263 (M + H+, base
peak); HRMS calcd for C11H10F3O2S 263.0354, found 263.0357.
Also isolated in the above experiment was bis coupling product 20,
0.03 g (21%) as a yellow oil (Rf 0.30, SiO2, 0.05:1 EtOAc/hexane):
1H NMR (200 MHz, CDCl3) δ 0.90 (t, 6.4 Hz, 6H), 1.32 (m, 12H),
(12) Seyferth, D.; Vick, S. C. J. Organomet. Chem. 1978, 144, 1.
(13) Corey, E. J.; Wollenberg, R. H. J. Am. Chem. Soc. 1974, 96, 5581.
(14) Stille, J. K.; Simpson, J. H. J. Am. Chem. Soc. 1987, 109, 2138.

4290 J. Am. Chem. Soc., Vol. 118, No. 18, 1996
Xiang et al.
2-Phenyl-4-(trimethylsilyl)-(E)-1,3-butadienyl Trifluoromethyl
Sulfone (13b) Dienyl triflone 13b was prepared from vinyl iodide
Z-10b, using a procedure similar to that described for 13a. Product
13b was obtained as a yellow oil in 72% yield (Rf 0.50, SiO2, 0.05:1
EtOAc/hexane): 1H NMR (200 MHz, CDCl3) δ 0.15 (s, 9H), 6.12 (s,
1H), 6.40 (d, 19.3 Hz, 1H), 7.27-7.49 (m, 5H), 7.84 (d, 19.0 Hz, 1H);
13C NMR (50 MHz, CDCl3) δ -1.35, 115.56, 120.59 (q, JC,F ) 326
Hz), 129.16, 129.52, 130.95, 137.03, 137.55, 152.95, 164.88; mass
spectrum (CI), 335 (M + H+, base peak); HRMS calcd for C14H17F3O2-
SSi 334.0671, found 334.0671.
yield (Rf 0.35, SiO2, 0.05 ether/hexane): 1H NMR (200 MHz, CDCl3)
δ 0.92 (t, 6.5 Hz, 3H), 1.36 (m, 6H), 1.65 (m, 2H), 2.65 (t, 7.3 Hz,
2H), 6.02 (s, 1H), 7.19 (d, 16.2 Hz, 1H), 7.39-7.60 (m, 5H), 7.97 (d,
16.2 Hz, 1H); 13C NMR (50 MHz, CDCl3) δ14.50, 23.00, 29.43, 29.82,
31.93, 35.20, 114.73, 120.60 (q, JC,F ) 326 Hz), 121.39, 128.64, 129.52,
130.81, 135.68, 140.98, 165.59; mass spectrum (CI), 347 (M + H+,
base peak); HRMS calcd for C17H21F3O2S 346.1214, found 346.1207.
(Z)-1-(Tributylstannyl)-1-[(Trifluoromethyl)sulfonyl]oct-1-ene (Z-
27a). Under argon, tributyltin hydride (0.35 mL, 0.13 mmol) was added
slowly to octynyl triflone 9a (0.299 g, 0.12 mmol, neat) at 0 °C. Once
the addition was complete, the reaction mixture was allowed to warm
to 25 °C for 3 h. The reaction was complete as monitored by NMR.
The resulting oil was purified with column chromatography (silica gel
deactivated with acetone, eluent pentane) to afford Z-27a (0.553 g,
84%) as a colorless oil: 1H NMR (300 MHz, CDCl3) δ 0.91 (m, 12H),
1.12 (m, 6H), 1.29 (m, 12H), 1.50 (m, 8H), 2.35 (m, 2H), 7.68 (t, 7.32
Hz, JSn,H ) 67 Hz, 1H); 13C NMR (50 MHz, CDCl3) δ 12.82, 14.05,
14.45, 22.96, 27.60, 28.83, 29.11, 29.53, 32.03, 35.34, 120.63 (q, JC,F
) 327 Hz), 137.96, 170.91; mass spectrum (EI), 477 (M - Bu, base
peak); mass spectrum (CI), 477 (M + H+ - HBu, base peak); HRMS
calcd for C17H32F3O2S116Sn 473.1092, found 473.1093.
(Z)-2-(2-Furyl)-2-Phenyl-1-[(trifluoromethyl)sulfonyl]ethene (13f).
Triflone 13f was prepared from vinyl iodide Z-10b, using a procedure
similar to that described for 13a. Product 13f was obtained as a yellow
oil in 90% yield (Rf 0.30, SiO2, 0.05:1 EtOAc/hexane): 1H NMR (200
MHz, CDCl3) δ 6.23 (s, 1H), 6.61 (dd, 1.8 Hz, 4.04 Hz, 1H), 6.80 (d,
3.5 Hz, 1H), 7.44-7.56 (m, 5H), 7.75 (d, 1.8, 1H); 13C NMR (50 MHz,
CDCl3) δ 113.32, 113.88, 120.58 (q, JC,F ) 327 Hz), 121.46, 129.34,
130.01, 131.98, 137.53, 147.74, 148.46, 150.79; mass spectrum (EI),
302 (M+, 0.20), 233 (M - CF3, 0.25), 169 (M - SO2CF3, 0.27); mass
spectrum (CI), 303 (M + H+, base peak); HRMS calcd for C13H9F3O3S
302.0225, found 302.0224.
(Z)-1-(Triphenylstannyl)-1-[(trifluoromethyl)sulfonyl]oct-1-ene (Z-
27b). This compound was prepared from the reaction of octynyl triflone
9a and triphenyltin hydride (Aldrich), using a procedure similar to that
described for Z-27a. Product Z-27b was obtained as a yellow oil in
95% yield (Rf 0.40, SiO2, 0.05:1 ether/hexane): 1H NMR (200 MHz,
CDCl3) δ 0.82 (t, 7.0 Hz, 3H), 0.91-1.33 (m, 8H), 2.24 (dt, 7.4 Hz,
7.7 Hz, 2H), 7.35-7.76 (m, 15H), 7.97 (t, 7.7 Hz, JSn,H ) 90 Hz, 1H);
13C NMR (50 MHz, CDCl3) δ 14.37, 23.08, 28.16, 29.20, 31.94, 35.87,
120.53 (q, JC,F ) 323 Hz), 129.41, 130.34, 137.00, 137.31, 137.72,
173.42; mass spectrum (CI), 517 (M + H+ - C6H5, base peak); HRMS
calcd for C21H24F3O2S116Sn 513.0466, found 513.0461.
3-[(Trifluoromethyl)sulfonyl]-(E)-deca-1,3-diene (E-14a). Dienyl
triflone E-14a was prepared from vinyl iodide Z-11a, using a procedure
similar to that described for Z-12a. Product E-14a was obtained as a
yellow oil in 96% yield (Rf 0.45, SiO2, 0.05:1 EtOAc/hexane): 1H NMR
(300 MHz, CDCl3) δ 0.89 (m, 3H), 1.30 (m, 6H), 1.53 (m, 2H), 2.46
(q, 7.4 Hz, 2H), 5.71 (dd, 11.7, 6.0 Hz, 2H), 6.39 (dd, 11.7 Hz, 6 Hz,
1H), 7.14 (t, 7.5 Hz, 1H); 13 C NMR (75 MHz, CDCl3) δ 14.07, 22.56,
28.34, 28.95, 29.79, 31.51, 120.04 (q, JC,F ) 325 Hz), 124.45, 124.79,
148.09, 154.18; mass spectrum (CI), 271 (M + H+, 0.14), 137 (M +
H+-HSO2CF3, 1.00); HRMS calcd for C11H18F3O2S 271.0980, found
271.0983.
Acknowledgment. We thank the National Institutes of
Health (GM 32693) for partial support of this work. Special
thanks are due to Rao Bhandaru and Jack Barnes for assistance
in obtaining the NOE spectra. Arlene Rothwell provided the
MS data.
(E)-1-(2-Furyl)-1-[(-2-trifluoromethyl)sulfonyl]oct-1-ene (E-14f).
Triflone E-14f was prepared from vinyl iodide Z-11a, using a procedure
similar to that described for 12c. Product E-14f was obtained as a
colorless oil in 83% yield (Rf 0.30, SiO2, 0.05 ether/hexane): 1H NMR
(200 MHz, CDCl3) δ 0.89 (m, 3H), 1.29 (m, 6H), 1.57 (m, 2H), 2.55
(q, 7.5 Hz, 2H), 6.51 (dd, 1.8 Hz, 3.6 Hz, 1H), 6.80 (d, 3.6 Hz, 1H),
7.32 (t, 7.7 Hz, 1H), 7.56 (d, 1.8 Hz, 1H); 13C NMR (50 MHz, CDCl3)
δ 14.48, 22.94, 28.65, 29.35, 31.09, 31.88, 112.03, 115.03, 120.32 (q,
JC,F ) 327 Hz), 126.74, 142.72, 144.94, 156.93; mass spectrum (CI),
367 (M + C4H9+, 0.74), 310 (M + H+, 0.07), 177 (M + H+ - HSO2-
CF3, 1.00); HRMS calcd for C13H17F3O3S 310.0851, found 310.0854.
Supporting Information Available: 1H and 13C NMR
spectra of all new compounds (48 pages). This material is
contained in many libraries on microfiche, immediately follows
this article in the microfilm version of the journal, can be ordered
from the ACS, and can be downloaded from the Internet; see
any current masthead page for ordering information and Internet
access instructions.
(1E,3E)-2-n-Hexyl-4-phenyl-1-[(trifluoromethyl)sulfonyl]buta-
1,3-diene (26). Dienyl triflone 26 was prepared from the reaction of
phenyl iodide and tin reagent 12c, using a procedure similar to that
described for Z-12a. Product 26 was obtained as a yellow oil in 91%
JA954303I