Palladium-catalyzed arylation of allylic benzoates using hypervalent siloxane derivatives

Article abstract of DOI:10.1021/jo010627f

Palladium-catalyzed cross-coupling of hypervalent arylsiloxane derivatives proceeded in good to excellent yields with allylic benzoates. Arylation occurred with complete inversion of configuration. The scope and limitations of this reaction, an alternative to the Stille coupling, is summarized.

Full text of DOI:10.1021/jo010627f

J . Org. Chem. 2001, 66, 7159-7165
7159
P a lla d iu m -Ca ta lyzed Ar yla tion of Allylic Ben zoa tes Usin g
Hyp er va len t Siloxa n e Der iva tives†
Reuben Correia and Philip DeShong*
Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
pd10@umail.umd.edu
Received J une 19, 2001
Palladium-catalyzed cross-coupling of hypervalent arylsiloxane derivatives proceeded in good to
excellent yields with allylic benzoates. Arylation occurred with complete inversion of configuration.
The scope and limitations of this reaction, an alternative to the Stille coupling, is summarized.
In tr od u ction
aryl- and vinyl- fluorosilanes.15,16 The limitations of this
method are that the synthesis of fluorosilanes is a
multistep process and fluorosilanes are hydrolytically
unstable.
Palladium-catalyzed carbon-carbon bond forming re-
actions of allylic esters have been widely used in organic
synthesis.1-6 Particularly notable has been the develop-
ment of couplings of stabilized nucleophiles such as
malonate. Carbon-carbon bond couplings of more basic
nucleophiles have proven to be problematic. One solution
to this limitation has been to employ stannanes as
nucleophilic surrogates (Stille coupling).7 Stille couplings
of aryl- and vinylstannanes with allylic acetates and
halides have been used widely due to the excellent yields
of adducts and the regioselectivity of the coupling proc-
ess.4,7 However, stannanes have several limitations for
practical organic synthesis: tin(IV) derivatives are toxic,
the removal of tin byproducts is problematic, and the
coupling reaction displays modest stereoselectivity.4,8
Other coupling reagents have been developed in an effort
to overcome the limitations of stannanes. Fiaud and
Legros have performed palladium-catalyzed couplings of
sodium tetraphenylborate with allylic acetates.9 Hiyama
and Hatanaka have carried out fluoride-promoted pal-
ladium-catalyzed couplings of allylfluorosilanes with aryl
halides,10-14 as well as couplings of allylic carbonates with
Our lab had previously demonstrated that hypervalent
silicate anions such as tetrabutylammonium triphenyldi-
fluorosilicate (TBAT) coupled with allylic benzoates in
the presence of a palladium catalyst to afford products
in good yields.8 However, there were two limitations of
the TBAT methodology, the first being that only one
phenyl group of the three present in the reagent was
transferred. Also, the preparation of TBAT and similar
reagents is a multistep process.17 These limitations were
overcome by preparing hypervalent silicates in situ from
arylsiloxanes.18 The methodology employing siloxanes18-22
and other silane derivatives23-29 has been used to prepare
unsymmetrical biaryls from aryl halides. Similarly, it was
demonstrated that siloxanes18 and other silane deriv-
atives23,30-39 could be used to transfer vinyl groups to aryl
(15) Hiyama, T.; Hatanaka, Y.; Mori, A.; Matsuhashi, H.; Asai, S.;
Hirabayashi, K. Bull. Chem. Soc. J pn. 1997, 70, 1943-1952.
(16) Hiyama, T.; Hatanaka, Y.; Matsuhashi, H.; Kuroboshi, M.
Tetrahedron Lett. 1995, 36, 1539-1540.
(17) DeShong, P.; Handy, C. J .; Lam, Y. J . Org. Chem. 2000, 65,
3542-3543.
(18) DeShong, P.; Mowery, M. E. J . Org. Chem. 1999, 64, 1684-
1688.
(19) DeShong, P.; Mowery, M. E. Org. Lett. 1999, 1, 2137-2140.
(20) DeShong, P.; Handy, C. J .; Mowery, M. E. Pure Appl. Chem.
2000, 72, 1655-1658.
(21) Shibata, K.; Miyazawa, K.; Goto, Y. Chem. Commun. 1997,
1309-1310.
(22) Nolan, S. P.; Lee, H. M. Org. Lett. 2000, 2, 2053-2055.
(23) Hiyama, T. In Metal-catalyzed Cross-coupling Reactions; Dieder-
ich, F., Stang, P. J ., Eds.; Wiley-VCH: Weinheim, 1998; pp 421-453.
(24) Hiyama, T.; Mori, A.; Hirabayashi, K.; Kawashima, J .; Nishi-
hara, Y. Org. Lett. 1999, 1, 299-301.
(25) Hiyama, T.; Mori, A.; Hirabayashi, K.; Kawashima, J .; Suguro,
M.; Nishihara, Y. J . Org. Chem. 2000, 65, 5342-5349.
(26) Hiyama, T.; Homsi, F.; Nozaki, K. Tetrahedron Lett. 2000, 41,
5869-5872.
(27) Hiyama, T.; Homsi, F.; Hosoi, K.; Nozaki, K. J . Organomet.
Chem. 2001, 624, 208-216.
(28) Denmark, S. E.; Wu, Z. Org. Lett. 1999, 1, 1495-1498.
(29) Mori, A.; Hirabayashi, K.; Kondo, T.; Toriyama, F.; Nishihara,
Y. Bull. Chem. Soc. J pn. 2000, 73, 749-750.
(30) Ito, Y.; Tamao, K.; Kobayashi, K. Tetrahedron Lett. 1989, 30,
6051-6054.
* To whom correspondence should be addressed. Telephone: 301-
405-1892. Fax: 301-314-9121.
† This manuscript is dedicated to Steven M. Weinreb on the occasion
of his 60th birthday.
(1) Diederich, F.; Stang, P. J ., Eds. Metal-catalyzed Cross-coupling
Reactions; Wiley-VCH: Weinheim, 1998.
(2) Tsuji, J . Palladium Reagents and Catalysts. Innovations in
Organic Synthesis; J ohn Wiley & Sons: New York, 1995; pp 290-422.
(3) Godleski, S. A. In Comprehensive Organic Synthesis; Trost, B.
M., Ed.; Pergamon Press: New York, 1991; Vol. 4, pp 585-661.
(4) Farina, V.; Krishnamurthy, V.; Scott, W. J . In Organic Reactions;
Paquette, L. A., Ed.; J ohn Wiley & Sons: New York, 1997; Vol. 50, pp
1-652.
(5) Hegedus, L. S. Coord. Chem. Rev. 1996, 147, 443-545.
(6) Suzuki, A.; Miyaura, N. Chem. Rev. 1995, 95, 2457-2483.
(7) Stille, J . K.; Hegedus, L. S.; Del Valle, L. J . Org. Chem. 1990,
55, 3019-3023.
(8) DeShong, P.; Brescia, M. R. J . Org. Chem. 1998, 63, 3156-3157.
(9) Fiaud, J . C.; Legros, J . Y. Tetrahedron Lett. 1990, 31, 7453-
7456.
(10) Hiyama, T.; Mori, A.; H., M.; Fujita, A.; Tanaka, M.; Hiraba-
yashi, K.; Shimizu, M. Organometallics 1996, 15, 5762-5765.
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10.1021/jo010627f CCC: $20.00 © 2001 American Chemical Society
Published on Web 09/27/2001

7160 J . Org. Chem., Vol. 66, No. 21, 2001
Correia and DeShong
Sch em e 1
Sch em e 3
Sch em e 2
Sch em e 4
and vinyl halides. In this paper, we report that the
hypervalent silicates derived from arylsiloxanes undergo
aryl transfer to allylic benzoates in excellent yields. The
coupling is highly regio- and stereoselective.
in yield due to steric factors from the ortho-substituent.
Similarly, benzoate 3 underwent arylation with m- and
p- anisolylsiloxanes in high yields (entries 4-6). However,
o-anisolylsiloxane 21 gave only 9% of alkene 22 (entry
7). The major products were 1,3-cyclohexadiene and
anisole. Previous studies in our lab had demonstrated
that the silicate derived from siloxane 21 was particularly
prone to protodesilylation.43,44 The unique behavior of
siloxane 21 has been attributed to coordination of the
o-methoxy group to silicon.
This coupling reaction also worked well with siloxanes
having chloro or disubstituted amino substituents on the
phenyl group. Thus, benzoate 3 coupled with siloxanes
23 and 25 in yields of 87% and 84%, respectively (entries
8 and 9). However, aniline siloxane 27 produced only 34%
of the expected product 28 (entry 10).
Resu lts a n d Discu ssion
Treatment of phenyl triethoxysilane (1) with an equi-
molar amount of tetrabutylammonium fluoride (TBAF)
resulted in the in situ formation of hypervalent fluoro-
silicate anion 2 (Scheme 1).17-20,40-42 Subsequent coupling
of silicate 2 with benzoate 3 in the presence of a Pd(0)
catalyst afforded phenylated product 4 in 95% yield.
To assess the stereoselectivity of the cross-coupling
reaction, carvyl benzoates 5 and 7 were employed as
substrates (Scheme 2). cis-Benzoate (+)-5 coupled with
PhSi(OEt)3/TBAF to afford exclusively trans-arene (()-
6, the product of inversion of configuration. Analogously,
trans-benzoate (-)-7 was transformed with complete
inversion of configuration to cis-arene (()-8 in 84% yield.
It should be noted that alkenes 6 and 8 were racemic
since a meso π-allyl-Pd complex was an intermediate in
each transformation.
To confirm that these arylations occurred in a highly
stereoselective manner, benzoate (+)-5 was allowed to
react with siloxanes 9 and 15, respectively. In each case,
the anticipated product resulting from inversion of con-
figuration was the only product obtained (entries 11 and
12).
The regioselectivity of the coupling reaction was in-
vestigated using acyclic allylic ester derivatives. As
summarized in Scheme 3, trans-cinnamoyl benzoate (31)
coupled with both PhSi(OEt)3/TBAF and TBAT to give
alkene 32 in 95% and 81% yields, respectively. In both
cases, only regioisomer 32, derived from attack of phenyl
at the less-substituted terminus of the allyl system, was
observed. The yields of arylation of this substrate were
excellent; by comparison, Stille coupling of benzoate 31
with phenyl trimethylstannane, gave 57% of alkene 32.7
Finally, benzoate 33 coupled with PhSi(OEt)3/TBAF to
afford alkene 34 in 91% yield. In this coupling, traces of
the alternative regioisomer were detected by 1H NMR
The scope and limitations of the coupling reaction were
assessed employing a variety of arylsiloxane derivatives,
and the results are summarized in the table. The yields
of arylated products were generally excellent with silox-
anes having methyl and methoxy substituents on the
phenyl group. In addition, the position of substitution was
generally inconsequential for the coupling. For example,
benzoate 3 coupled with o-, m- and p-tolylsiloxanes in
high yields (entries 1-3) with no significant reduction
(35) Denmark, S. E.; Neuville, L. Org. Lett. 2000, 2, 3221-3224.
(36) Denmark, S. E.; Wang, Z. Synthesis 2000, 999-1003.
(37) Denmark, S. E.; Wang, Z. J . Organomet. Chem. 2001, 624, 372-
375.
(38) Denmark, S. E.; Pan, W. Org. Lett. 2001, 3, 61-64.
(39) Denmark, S. E.; Wang, Z. Org. Lett. 2001, 3, 1073-1076.
(40) DeShong, P.; Mowery, M. E. J . Org. Chem. 1999, 64, 3266-
3270.
(41) Horn, A. H. Chem. Rev. 1995, 95, 1317-1350.
(42) Corriu, R. J . P.; Chuit, C.; Reye, C.; Young, J . C. Chem. Rev.
1993, 93, 1371-1448.
(43) DeShong, P.; Handy, C. J .; Correia, R., unpublished results.
(44) The following control experiments have been performed: heat-
ing equimolar quantities of siloxane 21 and TBAF in the absence of
benzoate 3 gave anisole rapidly and in high yield. On the other hand,
when equimolar quantities of siloxane 15 and TBAF were heated in
THF, no trace of anisole was detected.

Pd-Catalyzed Arylation of Allylic Benzoates
J . Org. Chem., Vol. 66, No. 21, 2001 7161
Ta ble 1. P a lla d iu m -Ca ta lyzed Ar yla tion of Cyclic Allylic Ben zoa tes
a
b
50% of 1,3-cyclohexadiene formed. 27% starting material recovered.
analysis of the crude reaction mixture. The coupling
reaction of silicates with allylic esters that proceed
through highly stabilized π-allyl complexes was less
efficient. For example, benzoate 35 coupled with TBAT,
an isolable silicate, to give a moderate yield of the
expected adduct 36 (Scheme 4). On the other hand,
benzoate 35 coupled with the in situ-derived silicate from
PhSi(OEt)3/TBAF to produce alkenes 32 and 37 in low
yield, respectively. A control experiment demonstrated
that the formation of alkene 37 resulted from isomeriza-

7162 J . Org. Chem., Vol. 66, No. 21, 2001
Correia and DeShong
Sch em e 5
in parts per million (δ) relative to the nondeuterated solvent
peak. Coupling constants (J values) are reported in hertz (Hz),
and spin multiplicities are indicated by the following sym-
bols: s (singlet), d (doublet), t (triplet), q (quartet), m (mul-
tiplet), br s (broad singlet). Infrared spectra were recorded as
solutions in CCl4. Band positions are given in reciprocal
centimeters (cm-1) and relative intensities are listed as br
(broad), s (strong), m (medium), or w (weak). Thin-layer
chromatography (TLC) was performed with the compounds
being identified in one or more of the following manners: UV
(254 nm), iodine, or vanillin/sulfuric acid charring. Flash
chromatography data is reported as (column diameter in mm,
column height in cm, solvent). The enantiomeric composition
of all compounds was determined by HPLC analysis using a
Chiralpak AD column. In all cases, a baseline separation of
the enantiomers was obtained.
tion of the alkene 36, the expected product of the coupling
reaction, under the basic reaction conditions. Formation
of alkene 32, the reduction product of benzoate 35 was
unexpected and is attributed to intermediacy of highly
conjugated allylic anion 40 generated by displacement
from palladium-allyl complex 38 as shown in Scheme
5. This remarkable displacement was observed only with
benzoate 35 and indicated that formation of a highly
stabilized anion (i.e., 40) was a requirement for the
reaction. Support for this mechanistic hypothesis was
production of biphenyl in equimolar amounts to the
alkene 32 (see Scheme 5). Attempts to trap anion 40 with
deuterium (D2O), benzaldehyde, or methyl iodide were
unsuccessful.
Tetrahydrofuran (THF) was distilled from sodium/benzo-
phenone ketyl. Pyridine and methylene chloride (CH2Cl2) were
distilled from calcium hydride. Methanol (MeOH) was stored
over molecular sieves. Glassware used in the reactions de-
scribed below was dried for a minimum of 12 h in an oven at
120 °C. All reactions were run under an atmosphere of argon
unless otherwise noted. Phenyl triethoxysilane (1), tetra-
butylammonium fluoride (TBAF, 1.0 M solution in THF), and
cerium chloride heptahydrate (CeCl3‚7H2O) were purchased
from Aldrich. Bis(dibenzylideneacetone)palladium (Pd(dba)2)
was purchased from Acros. Sodium borohydride (NaBH4) was
purchased from Fisher. Tetrabutylammonium triphenyldi-
fluorosilicate (TBAT) was synthesized according to the proce-
dure of DeShong and Handy.17 All reported compounds were
Con clu sion
The results summarized above demonstrate that hy-
pervalent siloxane derivatives are versatile reagents in
transferring aryl groups to allylic benzoates in a highly
regio- and stereoselective manner. There are several
advantages of siloxane couplings compared to Stille
couplings with allylic systems, including mild reaction
conditions, stability, low toxicity and ease of preparation
of siloxane reagents,47,48,50 and the high stereoselectivity
of arylation with net inversion of configuration. The scope
and limitations of this methodology for the synthesis of
natural products will be reported in due course.
1
>95% pure as determined by H and 13C NMR spectroscopy.
Gen er a l P r oced u r e for th e Cr oss-Cou p lin g Rea ction s
Utilizin g Allylic Ben zoa tes. To a solution of 0.10 g (1.0
equiv) of the allylic benzoate, 0.10 equiv of Pd(dba)2, and 2.0
equiv of arylsiloxane in 10 mL of THF was added 2.0 equiv of
TBAF via syringe. The reaction mixture was degassed to
remove oxygen via two freeze-pump-thaw cycles and heated
at 50-60 °C under an argon atmosphere for 12-48 h. The
reaction mixture was quenched by the addition of 50 mL of
water. The aqueous layer was extracted with 4 × 50 mL of
Et2O, and the combined organic layers were dried over Na2SO4
and concentrated in vacuo. Purification of the residue by flash
chromatography yielded the cross-coupled adduct. The spectral
data of the individual compounds are reported below.
3-Ben zoylcycloh exen e (3). The benzoate 3 was prepared
according to the procedure of DeShong and Mowery.18 The IR,
1H NMR, and 13C NMR data were identical to the data
reported by DeShong and Mowery.18
Exp er im en ta l Section
Gen er a l Meth od s. Nuclear magnetic resonance (1H and
13C NMR) spectra were recorded on a 400 MHz spectrometer
in CDCl3 unless otherwise noted. Chemical shifts are reported
(45) Utagawa, A.; Hirota, H.; Ohno, S.; Takahashi, T. Bull. Chem.
Soc. J pn. 1988, 61, 1207-1211.
(46) Uesaka, N.; Saitoh, F.; Mori, M.; Shibasaki, M.; Okamura, K.;
Date, T. J . Org. Chem. 1994, 59, 5633-5642.
(47) Masuda, Y.; Murata, M.; Suzuki, K.; Watanabe, S. J . Org.
Chem. 1997, 62, 8569-8571.
(48) DeShong, P.; Manoso, A. S., submitted for publication in J . Org.
Chem.
(49) Kamigata, N.; Fukushima, T.; Satoh, A.; Kameyama, M. J .
Chem. Soc., Perkin Trans. 1 1990, 549-553.
(50) DeShong, P.; Ahn, C.; Soheili, A., manuscript in preparation.

Pd-Catalyzed Arylation of Allylic Benzoates
J . Org. Chem., Vol. 66, No. 21, 2001 7163
3-P h en ylcycloh exen e (4). Alkene 4 was prepared accord-
ing to the general procedure for the cross-coupling reaction
employing 0.081 g (0.40 mmol) of benzoate 3. The reaction
mixture was heated at 50 °C for 14 h. Purification of the
residue by flash chromatography (25 mm, 15 cm, pentane) gave
0.060 g (95%) of alkene 4. The IR, 1H NMR, and 13C NMR data
were identical to the data reported by DeShong and Mowery.18
(+)-(R,R)-cis-Ca r vyl Ben zoa t e (5). The benzoate (+)-5
was prepared according to the procedure of DeShong and
Mowery:18 IR (CCl4) 3073 (m), 2971 (m), 2920 (m), 1720 (s),
1646 (m), 1452 (m), 1270 (s), 1112 (s); 1H NMR (CDCl3) δ 1.58-
1.69 (m, 1H), 1.71 (s, 3H), 1.73 (s, 3H), 1.96-2.20 (m, 2H),
2.27-2.44 (m, 2H), 4.74 (s, 2H), 5.62-5.74 (m, 2H), 7.43 (t, J
) 7.5, 2H), 7.55 (t, J ) 7.5, 1H), 8.07 (d, J ) 7.5, 2H); 13C
NMR (CDCl3) δ 19.0, 20.5, 30.8, 34.0, 40.2, 73.8, 109.4, 126.0,
2859 (m), 2838 (m), 1608 (m), 1558 (m), 1487 (m), 1447 (m);
1H NMR (CDCl3) δ 1.47-1.79 (m, 3H), 1.94-2.12 (m, 3H), 2.33
(s, 3H), 3.36 (br s, 1H), 5.70 (dd, J ) 10.3, 2.0, 1H), 5.84-5.91
(m, 1H), 6.98-7.04 (m, 3H), 7.18 (t, J ) 7.2, 1H); 13C NMR
(CDCl3) δ 21.3, 21.4, 25.0, 32.6, 41.8, 124.8, 126.7, 128.1, 128.2,
128.4, 130.3, 137.8, 146.6; LRMS (EI) 173 ((M + 1), 11), 172
(M+), 74), 157 (47), 144 (32), 129 (100), 128 (37), 115 (32);
HRMS (EI) calcd for C13H16 172.1252 (M+), found 172.1244.
2-(Tr im eth oxysilyl)tolu en e (13). The siloxane 13 was
prepared according to the procedure of DeShong and Ahn.50
The 1H NMR and 13C NMR data were identical to the data
reported by DeShong and Ahn.50
3-(2-Meth ylp h en yl)cycloh exen e (14). Alkene 14 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.085 g (0.42 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 15 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, pentane) gave 0.056 g (77%) of alkene 14 as a colorless
oil: TLC Rf ) 0.69 (pentane); IR (CCl4) 3021 (m), 2933 (s),
128.3, 129.6, 130.5, 132.9, 133.1, 148.2, 166.4; [R]24 ) +17.1
D
1
(c ) 1.25, EtOH). The H NMR data were consistent with the
data reported by Utagawa et al. recorded at 60 MHz.45
(()-tr a n s-2-Meth yl-3-p h en yl-5-isop r op en yl-1-cycloh ex-
en e (6). Alkene (()-6 was prepared according to the general
procedure for the cross-coupling reaction employing 0.101 g
(0.395 mmol) of benzoate (+)-5. The reaction mixture was
heated at 50 °C for 14 h. Purification of the residue by flash
chromatography (25 mm, 15 cm, pentane) gave 0.070 g (83%)
of alkene (()-6. The IR, 1H NMR, and 13C NMR data were
identical to the data reported by DeShong and Brescia.8 HPLC
analysis and the optical rotation of alkene (()-6 confirmed that
it was racemic.
1
2858 (m), 2837 (m), 1487 (m), 1460 (m); H NMR (CDCl3) δ
1.42-1.79 (m, 3H), 1.94-2.17 (m, 3H), 2.34 (s, 3H), 3.61 (br s,
1H), 5.67 (dd, J ) 9.9, 2.0, 1H), 5.87-5.94 (m, 1H), 7.06-7.22
(m, 4H); 13C NMR (CDCl3) δ 19.2, 21.1, 25.0, 30.6, 37.7, 125.8,
125.9, 127.5, 128.3, 130.2, 130.4, 135.4, 144.3; LRMS (EI) 173
((M + 1), 4), 172 ((M+), 34), 129 (100), 128 (42), 115 (48); HRMS
(EI) calcd for C13H16 172.1252 (M+), found 172.1256.
4-(Tr ieth oxysilyl)a n isole (15). The siloxane 15 was pre-
pared according to the procedure of Masuda.47 The 1H NMR
and 13C NMR data were identical to the data reported by
Masuda.47
(-)-(R,S)-tr a n s-Ca r vyl Ben zoa te (7). The benzoate (-)-7
was prepared according to the procedure of Uesaka et al.46 The
IR and 1H NMR data were identical to the data reported by
Uesaka et al.46 13C NMR (CDCl3) δ 20.7, 20.9, 30.9, 33.7, 36.0,
71.2, 109.2, 127.9, 128.3, 129.6, 130.6, 131.0, 132.8, 148.6,
3-(4-Meth oxyp h en yl)cycloh exen e (16). Alkene 16 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.084 g (0.42 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 16 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, 10% CH2Cl2/pentane) gave 0.069 g (88%) of alkene 16.
The 1H NMR, 13C NMR, and MS data were identical to the
data reported by Goering et al.51
3-(Tr ieth oxysilyl)a n isole (17). The siloxane 17 was pre-
pared according to the procedure of DeShong and Manoso.48
The 1H NMR and 13C NMR data were identical to the data
reported by DeShong and Manoso.48
166.3; [R]26 ) -224.1 (c ) 1.28, EtOH).
D
(()-cis-2-Met h yl-3-p h en yl-5-isop r op en yl-1-cycloh ex-
en e (8). Alkene (()-8 was prepared according to the general
procedure for the cross-coupling reaction employing 0.100 g
(0.391 mmol) of benzoate (-)-7. The reaction mixture was
heated at 54 °C for 14 h. Purification of the residue by flash
chromatography (25 mm, 15 cm, pentane) gave 0.070 g (84%)
of alkene (()-8. The IR, 1H NMR, and 13C NMR data were
identical to the data reported by DeShong and Brescia.8 HPLC
analysis and the optical rotation of alkene (()-8 confirmed that
it was racemic.
3-(3-Meth oxyp h en yl)cycloh exen e (18). Alkene 18 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.081 g (0.40 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 12 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, 10% CH2Cl2/pentane) gave 0.066 g (88%) of alkene 18
as a colorless oil: TLC Rf ) 0.42 (10% CH2Cl2/pentane); IR
(CCl4) 3023 (m), 2935 (s), 2859 (m), 2836 (m), 1601 (s), 1485
(s), 1265 (s), 1057 (m); 1H NMR (CDCl3) δ 1.49-1.80 (m, 3H),
1.94-2.15 (m, 3H), 3.37 (br s, 1H), 3.78 (s, 3H), 5.70 (dd, J )
10.3, 2.0, 1H), 5.84-5.91 (m, 1H), 6.71-6.84 (m, 3H), 7.20 (t,
J ) 7.5, 1H); 13C NMR (CDCl3) δ 21.2, 25.0, 32.5, 41.8, 55.1,
111.1, 113.5, 120.2, 128.3, 129.1, 130.0, 148.3, 159.6; LRMS
(EI) 189 ((M + 1), 14), 188 ((M+), 100), 159 (41), 134 (33);
HRMS (EI) calcd for C13H16O 188.1201 (M+), found 188.1203.
1,2-Meth ylen ed ioxy-4-(tr ieth oxysilyl)ben zen e (19). The
siloxane 19 was prepared according to the procedure of
4-(Tr ieth oxysilyl)tolu en e (9). The siloxane 9 was pre-
pared according to the procedure of Masuda.47 The 1H NMR
and 13C NMR data were identical to the data reported by
Masuda.47
3-(4-Meth ylp h en yl)cycloh exen e (10). Alkene 10 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.090 g (0.45 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 12 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, pentane) gave 0.067 g (87%) of alkene 10 as a colorless
oil: TLC Rf ) 0.59 (pentane); IR (CCl4) 3021 (m), 2931 (s),
1
2858 (m), 2837 (m), 1512 (m), 1446 (m); H NMR (CDCl3) δ
1.46-1.78 (m, 3H), 1.93-2.10 (m, 3H), 2.31 (s, 3H), 3.36 (br s,
1H), 5.69 (dd, J ) 9.9, 2.0, 1H), 5.82-5.90 (m, 1H), 7.10 (s,
4H); 13C NMR (CDCl3) δ 21.0, 21.2, 25.0, 32.7, 41.4, 127.6,
128.1, 128.9, 130.4, 135.4, 143.6; LRMS (EI) 173 ((M + 1), 14),
172 ((M+), 100), 157 (60), 129 (87); HRMS (EI) calcd for C13H16
172.1252 (M+), found 172.1248. The 1H NMR data were
consistent with the data reported by Kamigata et al. recorded
at 60 MHz.49
1
DeShong and Manoso.48 The H NMR and 13C NMR data were
identical to the data reported by DeShong and Manoso.48
3-(3,4-Meth ylen ed ioxyp h en yl)cycloh exen e (20). Alkene
20 was prepared according to the general procedure for the
cross-coupling reaction employing 0.086 g (0.42 mmol) of
benzoate 3. The reaction mixture was heated at 60 °C for 14
h. Purification of the residue by flash chromatography (25 mm,
15 cm, 10% CH2Cl2/pentane) gave 0.075 g (87%) of alkene 20
as a colorless oil: TLC Rf ) 0.44 (10% CH2Cl2/pentane); IR
(CCl4) 3016 (m), 2926 (m), 2878 (m), 1508 (m), 1487 (s), 1442
3-(Tr ieth oxysilyl)tolu en e (11). The siloxane 11 was pre-
pared according to the procedure of DeShong and Manoso.48
The 1H NMR and 13C NMR data were identical to the data
reported by DeShong and Manoso.48
3-(3-Meth ylp h en yl)cycloh exen e (12). Alkene 12 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.086 g (0.43 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 10 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, pentane) gave 0.063 g (86%) of alkene 12 as a colorless
oil: TLC Rf ) 0.64 (pentane); IR (CCl4) 3022 (m), 2932 (s),
1
(m), 1252 (m), 1232 (m), 1042 (m); H NMR (CDCl3) δ 1.45-
1.78 (m, 3H), 1.91-2.13 (m, 3H), 3.32 (br s, 1H), 5.66 (dd, J )
(51) Goering, H. L.; Tseng, C. C.; Paisley, S. D. J . Org. Chem. 1986,
51, 2884-2891.

7164 J . Org. Chem., Vol. 66, No. 21, 2001
Correia and DeShong
9.9, 2.0, 1H), 5.83-5.89 (m, 1H), 5.90 (s, 2H), 6.64-6.76 (m,
3H); 13C NMR (CDCl3) δ 21.1, 25.0, 32.8, 41.5, 100.7, 108.0,
108.3, 120.5, 128.3, 130.3, 140.7, 145.7, 147.5; LRMS (EI) 203
((M + 1), 15), 202 ((M+), 100), 174 (28), 116 (20); HRMS (EI)
calcd for C13H14O2 202.0994 (M+), found 202.1002.
2-(Tr ieth oxysilyl)a n isole (21). The siloxane 21 was pre-
pared according to the procedure of DeShong and Ahn.50 The
1H NMR and 13C NMR data were identical to the data reported
by DeShong and Ahn.50
3-(2-Meth oxyp h en yl)cycloh exen e (22). Alkene 22 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.083 g (0.41 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 36 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, 10% CH2Cl2/pentane) gave 0.007 g (9%) of alkene 22.
The 1H NMR data were identical to the data reported by
Kocovsky et al.52 GC analysis of the crude reaction mixture
indicated the formation of 50% of 1,3-cyclohexadiene by
comparison with an authentic sample. Anisole (0.10 g) was
isolated and compared with an authentic sample by TLC, GC,
and 1H NMR spectroscopy.
1H NMR (CDCl3) δ 1.45-1.80 (m, 3H), 1.90-2.15 (m, 3H), 3.29
(br s, 1H), 3.57 (br s, 2H), 5.68 (dd, J ) 9.9, 2.0, 1H), 5.81-
5.88 (m, 1H), 6.64 (d, J ) 8.3, 2H), 7.01 (d, J ) 8.3, 2H); 13C
NMR (CDCl3) δ 21.1, 25.0, 32.7, 41.0, 115.2, 127.9, 128.5, 130.8,
136.8, 144.4; LRMS (EI) 174 ((M + 1),14), 173 ((M+), 100), 145
(70), 144 (79); HRMS (EI) calcd for C12H15N 173.1204 (M+),
found 173.1203.
(()-tr a n s-2-Meth yl-3-(4-m eth ylp h en yl)-5-isop r op en yl-
1-cycloh exen e (29). Alkene (()-29 was prepared according
to the general procedure for the cross-coupling reaction
employing 0.105 g (0.410 mmol) of benzoate (+)-5. The reaction
mixture was heated at 60 °C for 48 h. Purification of the
residue by flash chromatography (25 mm, 15 cm, pentane) gave
0.078 g (84%) of alkene (()-29 as a colorless oil: TLC Rf )
0.58 (pentane); IR (CCl4) 3085 (m), 2966 (m), 2917 (s), 2859
(m), 1644 (m), 1510 (m), 1448 (m); 1H NMR (CDCl3) δ 1.58 (s,
3H), 1.63 (s, 3H), 1.70-1.81 (m, 1H), 1.83-2.01 (m, 2H), 2.10-
2.28 (m, 2H), 2.32 (s, 3H), 3.32 (d, J ) 5.2, 1H), 4.61 (s, 1H),
4.64 (s, 1H), 5.70 (br s, 1H), 7.09 (s, 4H); 13C NMR (CDCl3) δ
20.9, 21.0, 22.6, 31.1, 34.6, 36.4, 45.2, 108.4, 123.8, 128.4, 128.8,
134.0, 135.2, 141.7, 149.8; LRMS (EI) 227 ((M + 1), 6), 226
((M+), 34), 183 (100), 143 (50); HRMS (EI) calcd for C17H22
226.1722 (M+), found 226.1729. HPLC analysis and the optical
rotation of alkene (()-29 confirmed that it was racemic.
(()-tr a n s-2-Meth yl-3-(4-m eth oxyph en yl)-5-isopr open yl-
1-cycloh exen e (30). Alkene (()-30 was prepared according
to the general procedure for the cross-coupling reaction
employing 0.100 g (0.391 mmol) of benzoate (+)-5. The reaction
mixture was heated at 60 °C for 20 h. Purification of the
residue by flash chromatography (25 mm, 15 cm, 10%
CH2Cl2/pentane) gave 0.073 g (78%) of alkene (()-30 as a
colorless oil: TLC Rf ) 0.49 (10% CH2Cl2/pentane); IR (CCl4)
3035 (m), 2934 (m), 2914 (m), 2835 (m), 1610 (m), 1509 (s),
1247 (s), 1042 (m); 1H NMR (CDCl3) δ 1.58 (s, 3H), 1.63 (s,
3H), 1.69-1.77 (m, 1H), 1.82-1.99 (m, 2H), 2.09-2.27 (m, 2H),
3.31 (d, J ) 5.2, 1H), 3.78 (s, 3H), 4.61 (s, 1H), 4.64 (s, 1H),
4-Ch lor o(tr ieth oxysilyl)ben zen e (23). The siloxane 23
1
was prepared according to the procedure of Masuda.47 The H
NMR and 13C NMR data were identical to the data reported
by Masuda.47
3-(4-Ch lor op h en yl)cycloh exen e (24). Alkene 24 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.082 g (0.41 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 12 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, pentane) gave 0.068 g (87%) of alkene 24 as a colorless
oil: TLC Rf ) 0.70 (pentane); IR (CCl4) 3023 (m), 2933 (s),
2860 (m), 2833 (m), 1490 (s), 1446 (m), 1408 (m); 1H NMR
(CDCl3) δ 1.44-1.76 (m, 3H), 1.93-2.14 (m, 3H), 3.36 (br s,
1H), 5.66 (dd, J ) 9.9, 2.0, 1H), 5.86-5.93 (m, 1H), 7.13 (d, J
) 8.3, 2H), 7.25 (d, J ) 8.3, 2H); 13C NMR (CDCl3) δ 21.0,
25.0, 32.6, 41.2, 128.3, 128.8, 129.1, 129.6, 131.6, 145.1; LRMS
(EI) 194 (26), 193 ((M + 1),12), 192 ((M+), 78), 157 (52), 129
(100); HRMS (EI) calcd for C12H13Cl 192.0706 (M+), found
192.0697.
5.69 (br s, 1H), 6.83 (d, J ) 8.7, 2H), 7.11 (d, J ) 8.7, 2H); 13
C
NMR (CDCl3) δ 20.9, 22.6, 31.1, 34.7, 36.6, 44.9, 55.2, 108.4,
113.5, 123.8, 129.4, 134.2, 136.9, 149.8, 157.8; LRMS (EI) 243
((M + 1), 8), 242 ((M+), 42), 199 (100), 159 (39), 121 (35); HRMS
(EI) calcd for C17H22O 242.1671 (M+), found 242.1679. HPLC
analysis and the optical rotation of alkene (()-30 confirmed
that it was racemic.
4-(Tr ieth oxysilyl)-N,N-d im eth yla n ilin e (25). The silox-
ane 25 was prepared according to the procedure of Masuda.47
The 1H NMR and 13C NMR data were identical to the data
reported by Masuda.47
tr a n s-Cin n a m oyl Ben zoa te (31). To a solution of 2.0 g
(15 mmol) of trans-cinnamaldehyde and 6.7 g (18 mmol) of
CeCl3‚7H2O in 25 mL of anhydrous MeOH kept at 0 °C was
added 0.69 g (18 mmol) of NaBH4 via a solid addition funnel.
The NaBH4 was slowly added over a period of 15 min. The
reaction was stirred at room temperature for 1 h and was
quenched by the addition of 50 mL of saturated NH4Cl. The
aqueous layer was washed with 3 × 50 mL of Et2O. The
combined organics were washed with 50 mL of saturated NaCl
and 2 × 50 mL of water, dried over Na2SO4, and concentrated
in vacuo. Purification of the residue by flash chromatography
(50 mm, 15 cm, 50% EtOAc/hexane) gave 1.2 g (60%) of trans-
cinnamyl alcohol. The 1H NMR and 13C NMR data were
identical to the data reported by Singaram et al.53
To a solution of 1.1 g (8.2 mmol) of trans-cinnamyl alcohol
and 2.1 mL (25 mmol) of pyridine in 40 mL of CH2Cl2 kept at
0 °C was added 3.0 mL (25 mmol) of benzoyl chloride via
syringe. The reaction was stirred at room temperature for 12
h and quenched by the addition of 50 mL of water. The aqueous
layer was washed with 3 × 50 mL of Et2O. The combined
organic layers were washed with 50 mL of each of the
following: 10% HCl, saturated NaHCO3, saturated NaCl and
water, dried over Na2SO4 and concentrated in vacuo. Purifica-
tion of the residue by flash chromatography (50 mm, 15 cm,
10% EtOAc/hexane) gave 1.9 g (96%) of benzoate 31 as a
colorless oil: TLC Rf ) 0.42 (10% EtOAc/hexane); IR (CCl4)
3057 (m), 3026 (m), 2948 (m), 1719 (s), 1601 (m), 1492 (m),
1451 (m), 1269 (s), 1176 (m), 1117 (m), 966 (m); 1H NMR
3-(4-N,N-Dim eth yla m in op h en yl)cycloh exen e (26). Al-
kene 26 was prepared according to the general procedure for
the cross-coupling reaction employing 0.080 g (0.40 mmol) of
benzoate 3. The reaction mixture was heated at 60 °C for 14
h. Purification of the residue by flash chromatography (25 mm,
15 cm, 5% EtOAc/hexane) gave 0.067 g (84%) of alkene 26 as
a yellow oil: TLC Rf ) 0.33 (5% EtOAc/hexane); IR (CCl4) 3020
(m), 2932 (m), 2857 (m), 1615 (m), 1518 (m); 1H NMR (CDCl3)
δ 1.47-1.79 (m, 3H), 1.91-2.14 (m, 3H), 2.90 (s, 6H), 3.31 (br
s, 1H), 5.70 (dd, J ) 9.9, 2.0, 1H), 5.80-5.87 (m, 1H), 6.70 (d,
J ) 8.7, 2H), 7.09 (d, J ) 8.7, 2H); 13C NMR (CDCl3) δ 21.2,
25.0, 32.7, 40.8, 40.9, 112.8, 127.7, 128.3, 130.9, 134.8, 149.1;
LRMS (EI) 202 ((M + 1),16), 201 ((M+), 100), 173 (61), 172
(47); HRMS (EI) calcd for C14H19N 201.1517 (M+), found
201.1518.
4-(Tr ieth oxysilyl)a n ilin e (27). The siloxane 27 was pre-
pared according to the procedure of DeShong and Manoso.48
The 1H NMR and 13C NMR data were identical to the data
reported by DeShong and Manoso.48
3-(4-Am in op h en yl)cycloh exen e (28). Alkene 28 was
prepared according to the general procedure for the cross-
coupling reaction employing 0.075 g (0.37 mmol) of benzoate
3. The reaction mixture was heated at 60 °C for 36 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, 25% EtOAc/hexane) gave 0.022 g (34%) of alkene 28
as a yellow oil: TLC Rf ) 0.23 (25% EtOAc/hexane); IR (CCl4)
3473 (w), 3391 (w), 3021 (m), 2931 (m), 1622 (m), 1514 (m);
(53) Singaram, B.; Fisher, G. B.; Fuller, J . C.; Harrison, J .; Alvarez,
S. G.; Burkhardt, E. R.; Goralski, C. T. J . Org. Chem. 1994, 59, 6378-
6385.
(52) Kocovsky, P.; Malkov, A. V.; Davis, S. L.; Baxendale, I. R.;
Mitchell, W. L. J . Org. Chem. 1999, 64, 2751-2764.

Pd-Catalyzed Arylation of Allylic Benzoates
J . Org. Chem., Vol. 66, No. 21, 2001 7165
(CDCl3) δ 4.98 (d, J ) 6.4, 2H), 6.41 (dt, J ) 15.9, 6.4, 1H),
6.74 (d, J ) 15.9, 1H), 7.22-7.59 (m, 8H), 8.09 (d, J ) 7.9,
2H); 13C NMR (CDCl3) δ 65.4, 123.2, 126.6, 128.0, 128.3, 128.5,
129.6, 130.1, 132.9, 134.2, 136.1, 166.3; LRMS (EI) 239 ((M +
1), 2), 238 ((M+), 16), 133 (43), 115 (83), 105 (100), 77 (45);
HRMS (EI) calcd for C16H14O2 238.0994 (M+), found 238.1003.
tr a n s-1,3-Dip h en yl-1-p r op en e (32). Alkene 32 was pre-
pared according to the general procedure for the cross-coupling
reaction employing 0.101 g (0.424 mmol) of benzoate 31. The
reaction mixture was heated at 60 °C for 12 h. Purification of
the residue by flash chromatography (25 mm, 15 cm, pentane)
gave 0.078 g (95%) of alkene 32. The IR, 1H NMR, and MS
data were identical to the data reported by Lawrence and
Muhammad.54 13C NMR (DMSO-d6) δ 38.6, 126.0, 126.1, 127.1,
128.4, 128.5, 128.6, 129.4, 130.5, 137.0, 140.0.
addition of 50 mL of water. The aqueous layer was washed
with 4 × 50 mL of Et2O. The combined organic layers were
washed with 50 mL of each of the following: 10% HCl,
saturated NaHCO3, saturated NaCl and water, dried over
Na2SO4, and concentrated in vacuo. Purification of the residue
by flash chromatography (50 mm, 15 cm, 10% EtOAc/hexane)
gave 1.9 g (90%) of benzoate 35: TLC Rf ) 0.42 (10% EtOAc/
hexane); IR (CCl4) 3068 (m), 3026 (m), 1724 (s), 1608 (m), 1496
(m), 1451 (m), 1265 (s), 1176 (m), 1107 (m), 963 (m); 1H NMR
(CDCl3) δ 6.47 (dd, J ) 15.9, 6.8, 1H), 6.67-6.77 (m, 2H), 7.21-
7.61 (m, 13H), 8.13 (d, J ) 7.9, 2H); 13C NMR (CDCl3) δ 76.6,
126.7, 127.0, 127.5, 128.0, 128.2, 128.4, 128.5, 128.6, 129.7,
130.3, 132.8, 133.0, 136.1, 139.2, 165.5; LRMS (EI) 314 ((M+),
2), 209 (36), 193 (33), 192 (100), 191 (33); HRMS (EI) calcd for
C
22H18O2 314.1307 (M+), found 314.1313.
1,3,3-Tr ip h en yl-1-p r op en e (36). A solution of 0.094 g (0.30
tr a n s-3-Ben zoyl-1-cycloh exyl-1-p r op en e (33). The ben-
zoate 33 was prepared from the corresponding alcohol, which
was prepared according to the procedure of Chini et al.55 The
mmol) of benzoate 35, 0.018 g (0.03 mmol) of Pd(dba)2, 0.008
g (0.03 mmol) of PPh3, and 0.324 g (0.60 mmol) of TBAT in 10
mL of THF was degassed via two freeze-pump-thaw cycles.
The reaction mixture was heated under reflux under an argon
atmosphere for 36 h and quenched by the addition of 50 mL
of water. The aqueous layer was extracted with 4 × 50 mL of
Et2O, and the combined organic layers were dried over Na2SO4
and concentrated in vacuo. Purification of the residue by flash
chromatography (25 mm, 15 cm, 10% CH2Cl2/hexane) gave
0.045 g (55%) of alkene 36: TLC Rf ) 0.32 (10% CH2Cl2/
hexane); IR (CCl4) 3085 (m), 3063 (m), 3028 (m), 2870 (w), 1601
(m), 1494 (s), 1450 (m), 966 (m); 1H NMR (CDCl3) δ 4.89 (d, J
) 7.5, 1H), 6.34 (d, J ) 15.9, 1H), 6.67 (dd, J ) 15.9, 7.5, 1H),
7.16-7.39 (m, 15H); 13C NMR (CDCl3) δ 54.2, 126.3, 126.5,
127.3, 128.5, 128.6, 128.7, 131.4, 132.6, 137.3, 143.5. The 1H
NMR data were consistent with the data reported by White-
sides et al. recorded at 60 MHz.58
1
IR and H NMR data of the alcohol were identical to the data
reported by Chini et al.55 To a solution of 1.2 g (8.6 mmol) of
trans-1-cyclohexylpropen-3-ol and 2.3 mL (27 mmol) of pyridine
in 40 mL of CH2Cl2 kept at 0 °C was added 3.8 mL (27 mmol)
of benzoyl chloride via syringe. The reaction was stirred at
room temperature for 12 h and quenched by the addition of
50 mL of water. The aqueous layer was washed with 3 × 50
mL of Et2O. The combined organic layers were washed with
50 mL of each of the following: 10% HCl, saturated NaHCO3,
saturated NaCl and water, dried over Na2SO4, and concen-
trated in vacuo. Purification of the residue by flash chroma-
tography (50 mm, 15 cm, 17% CH2Cl2/pentane) gave 1.9 g
(90%) of benzoate 33 as a colorless oil: TLC Rf ) 0.37 (17%
CH2Cl2/pentane); IR (CCl4) 2927 (m), 2847 (m), 1722 (s), 1449
(m), 1270 (s), 1107 (m), 973 (m); 1H NMR (CDCl3) δ 1.02-1.34
(m, 5H), 1.60-1.80 (m, 5H), 2.00 (br s, 1H), 4.76 (d, J ) 6.4,
2H), 5.63 (dt, J ) 15.5, 6.4, 1H), 5.80 (dd, J ) 15.5, 6.4, 1H),
7.43 (t, J ) 7.5, 2H), 7.54 (t, J ) 7.5, 1H), 8.06 (d, J ) 7.5,
2H); 13C NMR (CDCl3) δ 26.0, 26.1, 32.5, 40.4, 66.0, 121.3,
128.3, 129.6, 130.4, 132.8, 142.1, 166.4; LRMS (FAB) 245 ((M
+ 1), 3), 244 ((M+), 3), 123 (63), 105 (100), 81 (50); HRMS (FAB)
calcd for C16H20O2 244.1463 (M+), found 244.1468.
1,1,3-Tr ip h en yl-1-p r op en e (37). Alkene 37 was prepared
according to the general procedure for the cross-coupling
reaction employing 0.094 g (0.30 mmol) of benzoate 35. The
reaction mixture was heated under reflux for 14 h. Purification
of the residue by flash chromatography (25 mm, 15 cm,
1
pentane) gave 0.021 g (25%) of alkene 37. The IR and H NMR
data were identical to the data reported by Saito et al.59 Alkene
32 (0.015 g, 25%) was isolated and compared with an authentic
tr a n s-1-Cycloh exyl-3-p h en yl-1-p r op en e (34). Alkene 34
was prepared according to the general procedure for the cross-
coupling reaction employing 0.102 g (0.418 mmol) of benzoate
33. The reaction mixture was heated at 55 °C for 14 h.
Purification of the residue by flash chromatography (25 mm,
15 cm, pentane) gave 0.077 g (91%) of alkene 34 as a colorless
oil: TLC Rf ) 0.70 (pentane); IR (CCl4) 3029 (m), 2926 (s),
1
sample by TLC and H NMR spectroscopy. Biphenyl (0.012 g,
26%) was isolated and compared with an authentic sample by
TLC and 1H NMR spectroscopy.
Isom er iza t ion of Alk en e 36 t o Alk en e 37. Alkene 36
(0.024 g, 0.089 mmol) was subjected to the standard conditions
for the cross-coupling reaction employing 0.006 g (0.01 mmol)
of Pd(dba)2, 0.048 g (0.20 mmol) of PhSi(OEt)3, and 0.20 mL
(0.20 mmol) of TBAF in 10 mL of THF. The reaction mixture
was degassed to remove oxygen via two freeze-pump-thaw
cycles and heated under reflux for 14 h. Purification of the
residue by flash chromatography (25 mm, 15 cm, pentane) gave
0.022 g (92%) of alkene 37 which was compared with an
authentic sample by TLC and 1H NMR spectroscopy.
Attem p ted Tr a p p in g of An ion 40. Attempts to trap anion
40 by addition of trace quantities of D2O to the reaction
mixture, or by quenching the reaction with D2O, methyl iodide,
or benzaldehyde under a variety of conditions failed to provide
the expected adducts.
1
2852 (s), 1603 (w), 1543 (m), 1495 (m), 1449 (m), 970 (m); H
NMR (CDCl3) δ 1.00-1.32 (m, 5H), 1.58-1.77 (m, 5H), 1.94
(br s, 1H), 3.32 (d, J ) 5.6, 2H), 5.43-5.56 (m, 2H), 7.15-7.31
(m, 5H); 13C NMR (CDCl3) δ 26.1, 26.2, 33.1, 39.1, 40.6, 125.8,
126.1, 128.3, 128.5, 138.1, 141.2; LRMS (EI) 201 ((M + 1), 3),
200 ((M+), 16), 117 (45), 109 (100), 108 (34), 104 (95), 91 (45),
67 (74), 55(39); HRMS (EI) calcd for C15H20 200.1565 (M+),
found 200.1557. In this coupling reaction, traces (<2%) of the
alternative regioisomer were detected by GC and 1H NMR
analysis of the crude reaction mixture.
tr a n s-3-Ben zoyl-1,3-d ip h en yl-1-p r op en e (35). The ben-
zoate 35 was prepared from the corresponding alcohol, which
was prepared according to the procedure of Bosnich et al.56
Ack n ow led gm en t. We thank Dr. Yiu-Fai Lam and
Ms. Caroline Ladd for their assistance in obtaining
NMR and mass spectral data. The financial support of
the National Cancer Institute (CA-82169) is also ac-
knowledged.
Su p p or t in g In for m a t ion Ava ila b le: 1H NMR and 13C
NMR spectra of compounds whose spectra have been reported
in this paper. This material is available free of charge via the
Internet at http://pubs.acs.org.
1
The H NMR and 13C NMR data of the alcohol were identical
to the data reported by Baba et al.57 To a solution of 1.4 g (6.7
mmol) of trans-1,3-diphenylpropen-3-ol and 1.6 mL (19 mmol)
of pyridine in 50 mL of CH2Cl2 kept at 0 °C was added 2.3 mL
(19 mmol) of benzoyl chloride via syringe. The reaction was
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