Aromatic alkenylation using electrophilic organogallium reagent generated from allenylsilane and GaCl3

Article abstract of DOI:10.1016/S0040-4020(00)01043-7

Aromatic hydrocarbons are alkenylated with silylallene in the presence of GaCl₃ at -90°C. Organometallic electrophiles generated from the allene and GaCl₃ are the active species in this reaction. A modest level of ortho-selectivity is observed. While the silylallene reacts exclusively at the 2-position, 1,2-alkadiene reacts at the 1-position predominantly.

Full text of DOI:10.1016/S0040-4020(00)01043-7

TETRAHEDRON
Pergamon
Tetrahedron 57 (2001) 827±833
Aromatic alkenylation using electrophilic organogallium reagent
generated from allenylsilane and GaCl3
Yoshiyuki Kido, Fumi Yonehara and Masahiko Yamaguchip
Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
Received 21 March 2000; accepted 9 August 2000
AbstractÐAromatic hydrocarbons are alkenylated with silylallene in the presence of GaCl3 at 2908C. Organometallic electrophiles
generated from the allene and GaCl3 are the active species in this reaction. A modest level of ortho-selectivity is observed. While the
silylallene reacts exclusively at the 2-position, 1,2-alkadiene reacts at the 1-position predominantly. q 2001 Elsevier Science Ltd. All rights
reserved.
Alkyne and halogenated alkene are common reagents for the
electrophilic alkenylation of aromatic compounds.1,2
Although allene potentially is another attractive alkenyl-
ating reagent, their use has been quite limited.3,4 It may be
caused by the instability of the allene and/or alkenylated
product under acidic conditions. Previously, we reported
the Friedel±Crafts b-silylethenylation reaction using
organogallium cationic species derived from silylethyne 3
and GaCl3.2 The reaction of silylated 1,3-butadiyne 2 was
also studied, which exhibited unusually high ortho-selec-
tivity.5 It therefore appeared interesting to see if GaCl3
could be used for the aromatic alkenylation of silylallene
1, and to compare the behavior of 1 with that of 2 and 3
(Scheme 1). Described here is the electrophilic aromatic
C±C bond formation using allenes promoted by GaCl3.
Reactions of several alkenes are also conducted.
acid and tri¯uoromethanesulfonic acid were also not
effective.
The orientation of the aromatic substitution indicates an
electrophilic mechanism. It exhibits a modest tendency to
alkenylate the o-position of alkyl substituents: the reaction
of 1 and toluene gives a ca. 1:1 mixture of the o- and
p-products (Fig. 2). Reaction of silylethyne 3 and disilyl-
1,3,5,7-octatetrayne 4 takes place at the p-position pre-
dominantly,2,5 while disilylated 1,3-butadiyne 2 reacts at
the o-position selectively.5 This order of unsaturated
compounds must be re¯ecting some property of their
GaCl3 complex, although the origin is not clear at present.
The following examples also show such tendencies: reac-
tions of o-xylene or 1,2,3,4-tetrahydronaphthalene with 1
give mixtures of comparable amounts of two regioisomers.
In contrast, 3 reacts at the less hindered sites predominantly
for both substrates,2 and 2 at the more hindered sites.5 In
addition, while 3 does not react with 1,3,5-trimethyl-
benzene, 1 and 2 smoothly react at the hindered position
between two methyl groups.
Arene (3 mol. equivalents) and 1-triethylsilyl-1,2-propa-
diene (1) (1 mol. equivalent) were reacted with GaCl3
(1 mol equivalent) in dichloromethane at 2908C for
2±3 h. Then THF was added, and an aqueous workup
gave (E)-1-silyl-1-propen-2-ylated arene (Fig. 1). The
C±C bond formation takes place at the 2-position of 1,
and no product at the 1- or 3-positions was detected.
b-Cation stabilization by the silicon substituent probably
was playing an important role on the regioselectivity. As
in the reaction of silylethyne 3,2 the alkenylation is likely to
proceed via organogallium electrophiles rather than vinyl
cations generated by protonation of 1. Treatment of an
excess p-xylene and 1 with HCl and GaCl3 gave a complex
mixture of products, and not the alkenylated arene. Sulfuric
The complex formed from 1 and GaCl3 can be detected by
low temperature NMR studies (Scheme 2). When an equi-
molar amount of the compounds was mixed at 2858C, a low
®eld shift and broadening of the 1-H of 1 was observed. The
use of 2 mol. eq. of GaCl3 resulted in a further low ®eld shift
Keywords: gallium trichloride; organometallic electrophile; aromatic
alkenylation; allenylsilane.
* Corresponding author. Tel.: 122-217-6812; fax: 122-217-6811; e-mail:
yama@mail.pharm.tohoku.ac.jp
Scheme 1.
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)01043-7

828
Y. Kido et al. / Tetrahedron 57 (2001) 827±833
Figure 1. Aromatic alkenylation using silylallene 1 promoted by GaCl3.
and sharpening of 1-H, while the shift was subtle at 3-H. 2-C
also shifted to a low ®eld, and 3-C a high ®eld. It is likely
that GaCl3 and 1 form complex 5, where GaCl3 interacts
with the double bond close to the silyl group. p-Xylene then
attacks at the 2-position of 5, generating an arenium species
6. When the reaction of p-xylene and 1 was quenched with
D2O, no deuteration of the product 7 took place. It may be
because of the proton transfer of the allylgallium 6 giving 7
in the reaction mixture. Although this mechanism suggests
the catalysis by GaCl3, 10 mol% of GaCl3 fails to give the
product under these reaction conditions. Related proton
transfer is considered to occur in the reaction of 2 as well.5
1. When 1,2-undecadiene (8) was reacted with p-xylene at
2788C in the presence of GaCl3, an isomeric mixture of
allylated product (E)- and (Z)-9 (XˆH) and alkenylated
product (E)-10 was obtained with the former predominating
(Scheme 3). The alkyl substituent of 8 appears to stabilize
the allyl cation rather than the vinyl cation. Notably, workup
with D2O gives monodeuterated 9 (XˆD) and non-deuter-
ated 10. The mixture of 9 (XˆD) and 10 is subjected
to ozonolysis, followed by reductive workup, giving
2-arylethanol, 1-arylethanol, and 1-nonanol. Deuterium is
incorporated only in the 2-arylethanol at the 1-position, as
indicated by D-NMR. The compound 9 therefore should be
formed from the vinylgallium 11 by a similar mechanism
with the reaction of 3.2 Formation of non-deuterated 10
An alkylallene shows different behavior from the silylallene
Figure 2. Ortho/para-selectivity in the aromatic substitution promoted by GaCl3.
Scheme 2.

Y. Kido et al. / Tetrahedron 57 (2001) 827±833
829
Scheme 3.
probably involves the proton transfer as described for 1 in
Scheme 2. It may be reasonable that the allylgallium is more
reactive towards protonation than the vinylgallium species.
When the reaction was quenched with iodine, vinyl iodides
(E)-9 (XˆI), (Z)-9 (XˆI), and allylarene (E)-10 were
obtained. The iodides (E)-9 (XˆI) and (Z)-9 (XˆI) can be
converted stereospeci®cally to (Z)-9 (XˆH) and (E)-9
(XˆH), respectively, by lithiation and aqueous treatments.
ation. Electrophiles generated from 12 appear to be less
stable than those from 1 or 3.
Reaction of 1-alkene is sensitive to the substrate structure.
3,3-Dimethyl-1-butene and styrene do not give the aromatic
alkylated product. In the case of 1-hexene (14), a mixture of
two isomers, 2-hexyl derivative 15 and 3-hexyl derivative
16, is obtained. Apparently, 16 is formed via the rearrange-
ment of the electrophile ®rst generated from 14. Notably,
this reaction proceeds catalytically concerning GaCl3, and
15 and 16 are obtained in 21 and 18% yields, respectively,
using 10 mol% of GaCl3 at 2508C (Scheme 5).
It turned out that monoole®ns also react with aromatic
hydrocarbons in the presence of GaCl3, although their reac-
tions are generally less effective than allenes. Treatment of
vinylsilane 12 with m-xylene gives a very low yield of the
4-silylethylated product 13 (Scheme 4). Polymerization of
12 under the reaction conditions competes with the alkyl-
1. Experimental
IR spectra were measured on a JASCO FT/IR-400 spectro-
1
photometer. H-NMR and 13C-NMR spectra were recorded
on a Varian Mercury NMR (400 MHz) with Me4Si as an
internal standard. Mass spectra were recorded on a JEOL
JMS-DX-303 or JMS-AX-500 spectrometer. Gel perme-
ation chromatography (GPC) was conducted with Recycling
Preparative HPLC LC-908 (Japan Analytical Industry Co.
Ltd).
1.1. (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2,5-dimethyl-
benzene
Scheme 4.
Under an argon atmosphere, to a solution of p-xylene
(0.38 ml, 3.0 mmol) in CH2Cl2 (8 ml) was added a solution
of GaCl3 (1.0 M in methylcyclohexane, 2.0 mL) at 2908C.
Then, 1 (154 mg, 1.0 mmol) in CH2Cl2 (2.0 mL) was added,
and the mixture was stirred at this temperature for 2 h. THF
(5.0 mL) was added, and stirring was continued for a further
30 min. The reaction was quenched by the addition of water.
The organic layer was separated, washed with brine, dried
over MgSO4, and concentrated. The residue was puri®ed by
¯ash chromatography (silica gel, n-hexane) to give (E)-1-(1-
triethylsilyl-1-propen-2-yl)-2,5-dimethylbenzene (195 mg,
75%). 1H-NMR (400 MHz, CDCl3) d 0.69 (6H, q, Jˆ
7.6 Hz), 1.00 (9H, t, Jˆ8.0 Hz), 2.05 (3H, d, Jˆ0.8 Hz),
2.24 (3H, s), 2.29 (3H, s), 5.26 (1H, q, Jˆ0.8 Hz), 6.89
(1H, br s), 6.93 (1H, d, Jˆ7.6 Hz), 7.03 (1H, d, Jˆ7.6 Hz).
Scheme 5.

830
Y. Kido et al. / Tetrahedron 57 (2001) 827±833
13C-NMR (100 MHz, CDCl3) d 4.89, 7.81, 19.42, 21.02,
23.86, 125.21, 127.02, 127.67, 129.88, 130.15, 134.71,
147.52, 155.59. IR (neat) 2952, 2911, 2873, 1604, 1457,
1239, 1015, 808, 768, 731 cm21. MS (EI, 70 eV) m/z (%)
260 (2, M1), 231 (100), 203 (14), 163 (21), 135 (16), 87
(14), 59 (14). HRMS (EI, 70 eV) Calcd. for C17H28Si:
260.1959. Found: 260.1957 (M1). The stereochemistry was
determined by NOE.
276.1915 (M1). (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2,6-
dimethylbenzene: 1H-NMR (400 MHz, CDCl3) d 0.69 (6H,
q, Jˆ8.1 Hz), 1.01 (9H, t, Jˆ8.1 Hz), 2.00 (3H, s), 2.24 (6H,
s), 2.29 (3H, s), 5.23 (1H, q, Jˆ 1.1 Hz), 6.99±7.05 (3H, m).
13C-NMR (100 MHz, CDCl3) d 4.88, 7.80, 19.82, 23.02,
125.26, 125.83, 127.11, 133.41, 147.10, 155.57. FT-IR
(neat) 2952, 2910, 2873, 1614, 1462, 1236, 1015, 796,
768, 738 cm21. MS (EI, 70 eV) m/z (%) 260 (10, M1),
231 (100), 203 (37), 101 (25). HRMS (EI, 70 eV) Calcd.
for C17H28Si: 260.1959. Found 260.1950 (M1). The epoxide
was converted to methyl 2-(2,4-dimethylphenyl)propionate
in three steps. (i) CH3SO3H, THF-H2O; 08C, 5 h.6 (ii)
NaClO2, NaH2PO4, 2-methyl-2-butene, t-BuOH-H2O, rt,
4 h. (iii) Me3SiCHN2. Methyl 2-(2,4-Dimethylphenyl)pro-
pionate: 1H-NMR (400 MHz, CDCl3) d 1.45 (3H, d,
Jˆ7.2 Hz), 2.29 (3H, s), 2.32 (3H, s), 3.64 (3H, s), 3.91
(1H, q, Jˆ7.2 Hz), 6.98 (1H, s), 6.99 (1H, br d,
Jˆ7.0 Hz), 7.13 (1H, d, Jˆ8.4 Hz). 13C-NMR (100 MHz,
CDCl3) d 18.14, 19.61, 21.05, 41.02, 52.00, 126.31, 126.97,
131.17, 135.29, 135.99, 136.36, 175.20. IR (neat) 2951,
1739, 1505, 1456, 1209, 1193, 855, 824 cm21. MS (EI,
70 eV) m/z (%) 192 (21, M1), 133 (100), 117 (6), 105 (7),
91 (7). HRMS (EI, 70 eV) Calcd for C12H16O2: 192.1149.
Found: 192.1161 (M1).
1.2. (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2-methyl-
benzene and (E)-1-(1-triethylsilyl-1-propen-2-yl)-4-
methylbenzene
1H-NMR (400 MHz, CDCl3) d 2-methyl isomer: 0.69 (6H,
q, Jˆ7.9 Hz), 1.00 (9H, t, Jˆ7.9 Hz), 2.07 (3H, s), 2.29 (3H,
s), 5.28 (1H, s), 7.05±7.10 (1H, m), 7.12±7.17 (3H, m);
4-methyl isomer: 0.68 (6H, q, Jˆ7.9 Hz), 0.98 (9H, t,
Jˆ7.7 Hz), 2.19 (3H, s), 2.34 (3H, s), 5.82 (1H, s), 7.13
(2H, d, Jˆ6.3 Hz), 7.36 (2H, d, Jˆ8.1 Hz). 13C-NMR
(100 MHz, CDCl3) d 2-methyl isomer: 4.69, 7.70, 19.81,
23.74, 125.44, 125.59, 126.37, 127.13, 130.00, 133.44,
147.76, 155.46; 4-methyl isomer: 4.79, 7.68, 21.07, 21.36,
122.82, 125.35, 128.70, 136.95, 141.61, 152.28. IR (neat,
mixture of isomers) 2952, 2910, 2873, 1598, 1457, 1237,
1015, 805, 768, 736 cm21. MS (EI, 70 eV, mixture of
isomers) m/z (%) 246 (5, M1), 217 (100), 189 (18), 177
(21), 149 (27), 121 (21). HRMS (EI, 70 eV, mixture of
isomers) Calcd for C16H26Si: 246.1802. Found: 246.1797
(M1).
1.4. (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2,3-dimethyl-
benzene and (E)-1-(1-triethylsilyl-1-propen-2-yl)-3,4-
dimethylbenzene
1H-NMR (400 MHz, CDCl3) d 2,3-dimethyl isomer: 0.69
(6H, q, Jˆ8.0 Hz), 1.00 (9H, t, Jˆ7.6 Hz), 2.06 (1H, m),
2.19 (3H, s), 2.27 (3H, s), 5.26 (1H, d, Jˆ0.8 Hz), 6.91±6.96
(1H, m), 7.01±7.04 (2H, m); 3,4-dimethyl isomer: 0.69 (6H,
q, Jˆ8.0 Hz), 0.98 (9H, t, Jˆ7.6 Hz), 2.18 (3H, s), 2.25 (3H,
s), 2.27 (3H, s), 5.79 (1H, s), 7.07 (1H, d, Jˆ7.8 Hz), 7.20
(1H, dd, Jˆ7.8, 2.0 Hz), 7.03 (1H, br s). 13C-NMR
(100 MHz, CDCl3) d 2,3-dimethyl isomer: 4.87, 7.82,
16.47, 20.60, 24.25, 125.05, 125.21, 124.89, 127.86,
131.83, 136.70, 148.01, 156.18; 3,4-dimethyl isomer: 4.95,
7.82, 19.50, 20.01, 21.51, 122.56, 122.84, 126.67, 129.22,
135.52, 135.89, 142.12, 152.39. IR (neat, mixture of
isomers) 2952, 2911, 2873, 1595, 1456, 1239, 1015, 811,
767, 733 cm21. MS (EI, 70 eV, mixture of isomers) m/z (%)
260 (6, M1), 231 (100), 191 (19), 163 (23), 135 (19). HRMS
(EI, 70 eV, mixture) Calcd for C17H28Si: 260.1959. Found:
260.1964 (M1).
1.3. (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2,4-dimethyl-
benzene and (E)-1-(1-triethylsilyl-1-propen-2-yl)-2,6-
dimethylbenzene
1H-NMR (400 MHz, CDCl3) d 2,4-dimethyl isomer: 0.68
(6H, q, Jˆ7.8 Hz), 0.99 (9H, t, Jˆ7.8 Hz), 2.05 (3H, d,
Jˆ1.1 Hz), 2.25 (3H, s), 2.30 (3H, s), 5.26 (1H, q,
Jˆ1.1 Hz), 6.89 (1H, br s), 6.94 (1H, d, Jˆ 7.6 Hz), 6.97
(1H, m), 6.98 (1H, d, Jˆ7.6 Hz). 13C-NMR (100 MHz,
CDCl3) d 2,4-dimethyl isomer: 4.85, 7.80, 19.88, 21.09,
23.95, 125.42, 126.01, 127.01, 130.69, 133.21, 135.77,
144.87, 155.28. IR (neat, mixture of isomers) 2952, 2911,
2873, 1605, 1457, 1236, 1015, 816, 768, 738 cm21. MS (EI,
70 eV, mixture of isomers) m/z (%) 260 (6, M1), 231 (100),
203 (16), 191 (21), 163 (28), 135 (21), 87 (15), 59 (14).
HRMS (EI, 70 eV, mixture of isomers) Calcd for
C17H28Si: 260.1959. Found: 260.1960 (M1). Treatment of
the isomeric mixture (6:1) with m-chloroperbenzoic acid
(CH2Cl2; 08C, 3 h) gave (E)-1-triethylsilyl-2-methyl-2-
(2,4-dimethylphenyl)oxirane (66%) and recovered (E)-1-
(1-triethylsilyl-1-propen-2-yl)-2,6-dimethylbenzene (12%).
(E)-1-Triethylsilyl-2-methyl-2-(2,4-dimethylphenyl)oxi-
rane. 1H-NMR (400 MHz, CDCl3) d 0.74 (3H, q,
Jˆ8.1 Hz), 0.75 (3H, q, Jˆ7.7 Hz), 1.06 (9H, t,
Jˆ7.7 Hz), 1.56 (3H, s), 2.28 (1H, s), 2.29 (3H, s), 2.36
(3H, s), 6.94 (1H, m), 6.97 (1H, d, Jˆ7.7 Hz), 7.25 (1H,
d, Jˆ7.7 Hz). 13C-NMR (100 MHz, CDCl3) d 3.41, 7.51,
19.26, 21.10, 23.00, 57.37, 61.93, 125.95, 126.26, 130.55,
134.24, 136.56, 140.04. IR (neat) 2954, 2876, 1615, 1456,
1365, 1237, 1016, 857, 822, 754, 719 cm21. MS (EI, 70 eV)
m/z (%) 276 (70, M1), 261 (28), 247 (100), 219 (34), 160
(58), 115 (52), 103 (30), 87 (62), 75 (40), 59 (39). HRMS
(EI, 70 eV) Calcd for C17H28OSi: 276.1908. Found:
1.5. (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2,3,4-tri-
methylbenzene and (E)-1-(1-triethylsilyl-1-propen-2-yl)-
3,4,5-trimethylbenzene
1H-NMR (400 MHz, CDCl3) d 2,3,4-trimethyl isomer: 0.68
(6H, q, Jˆ7.9 Hz), 1.00 (9H, t, Jˆ 7.9 Hz), 2.05 (3H, d,
Jˆ0.9 Hz), 2.19 (3H, s), 2.22 (3H, s), 2.28 (3H, s), 5.25
(1H, q, Jˆ0.9 Hz), 6.85 (1H, d, Jˆ 7.7 Hz), 6.95 (1H, d,
Jˆ7.7 Hz); 3,4,5-trimethyl isomer: 0.69 (6H, q, Jˆ7.9 Hz),
0.98 (9H, t, Jˆ7.9 Hz), 2.16 (3H, s), 2.17 (3H, d, Jˆ0.9 Hz),
2.30 (6H, s), 5.77 (1H, q, Jˆ 0.7 Hz), 7.11 (2H, s). 13C-
NMR (100 MHz, CDCl3) d 2,3,4-trimethyl isomer: 4.75,
7.69, 15.78, 17.00, 20.65, 24.31, 124.21, 125.06, 126.78,
131.66, 134.33, 135.07, 146.03, 156.54; 3,4,5-trimethyl
isomer: 4.75, 7.69, 15.16, 20.66, 21.39, 122.33, 124.62,
134.03, 135.81, 141.50, 152.54. IR (neat, mixture of

Y. Kido et al. / Tetrahedron 57 (2001) 827±833
831
isomers) 2952, 2910, 2873, 1609, 1457, 1239, 1015, 815,
768, 735 cm21. MS (EI, 70 eV, mixture of isomers) m/z (%)
274 (6, M1), 245 (100), 205 (17), 177 (24), 149 (20), 87
(21), 59 (13). HRMS (EI, 70 eV, mixture of isomers) Calcd
for C18H30Si: 274.2115. Found: 274.2117 (M1).
M1), 159 (100), 131 (26), 91 (29). HRMS (EI, 70 eV)
Calcd for C12H14O: 174.1044. Found: 174.1037 (M1).
1.8. (E)-1-(1-Triethylsilyl-1-propen-2-yl)naphthalene
and (E)-2-(1-triethylsilyl-1-propen-2-yl)naphthalene
1.6. (E)-1-(1-Triethylsilyl-1-propen-2-yl)-2,4,6-tri-
methylbenzene
1H-NMR (400 MHz, CDCl3, mixture of isomers) d 0.72 (q,
Jˆ 7.7 Hz), 0.73 (q, Jˆ7.7 Hz), 1.02 (t, Jˆ7.7 Hz), 1.04 (t,
Jˆ7.7 Hz), 2.25 (d, Jˆ0.9 Hz), 2.32 (d, Jˆ0.7 Hz), 5.52 (t,
Jˆ0.9 Hz), 6.01 (s), 7.16 (s), 7.256 (d, Jˆ7.0 Hz), 7.36±
7.47 (m), 7.65 (dd, Jˆ8.6, 1.9 Hz), 7.70 (d, Jˆ 8.1 Hz), 7.74
(d, Jˆ8.4 Hz), 7.79 (t, Jˆ6.6 Hz), 7.84 (br s), 8.00 (dd,
Jˆ7.3, 1.9 Hz). 13C-NMR (100 MHz, CDCl3, mixture of
isomers) d 4.77, 4.83, 7.77, 21.45, 24.64, 123.70, 123.98,
124.17, 124.67, 125.30, 125.48, 125.56, 125.67, 125.70,
125.99, 126.69, 127.40, 127.47, 128.21, 130.26, 132.69,
133.28, 133.73, 141.50, 146.05, 152.20, 154.14. IR (neat,
mixture of isomers) 3056, 2952, 2872, 1590, 1457, 1378,
1236, 1015, 813, 763, 733 cm21. MS (EI, 70 eV, mixture of
isomers) m/z (%) 282 (2, M1), 253 (11), 168 (36), 153 (45),
128 (100). HRMS (EI, 70 eV, mixture of isomers) Calcd for
C19H26Si: 282.1802. Found: 282.1795 (M1). Treatment of
the isomeric mixture (4:1) with RuCl3 (4 mol%) and NaIO4
(CCl4, CH3CN and H2O; rt, 2 h)7 gave a mixture of 2-acetyl-
naphthalene (59%) and 1-acetylnaphthalene (15%), the
structures of which were con®rmed by comparison with
authentic samples.
1H-NMR (400 MHz, CDCl3) d 0.68 (6H, q, Jˆ 7.9 Hz),
1.00 (9H, t, Jˆ7.9 Hz), 1.98 (3H, d, Jˆ0.9 Hz), 2.21 (6H,
s), 2.26 (3H, s), 5.21 (1H, q, Jˆ0.9 Hz), 6.84 (2H, s). 13C-
NMR (100 MHz, CDCl3) d 4.92, 7.80, 19.72, 21.02, 23.20,
125.40, 127.88, 133.33, 135.23, 144.37, 154.68. IR (neat)
2952, 2911, 2873, 1615, 1457, 1236, 1015, 849, 776,
737 cm21. MS (EI, 70 eV) m/z (%) 274 (15, M1), 245
(100), 217 (26), 177 (17), 149 (15), 101 (30), 87 (29), 73
(20), 59 (23). HRMS (EI, 70 eV) Calcd for C18H30Si:
274.2115. Found: 274.2122 (M1).
1.7. (E)-5-(1-Triethylsilyl-1-propen-2-yl)-1,2,3,4-tetra-
hydronaphthalene and (E)-6-(1-triethylsilyl-1-propen-2-
yl)-1,2,3,4-tetrahydronaphthalene
1H-NMR (400 MHz, CDCl3, mixture of isomers) d 0.68
(6H, q, Jˆ7.9 Hz), 0.69 (6H, q, Jˆ7.9 Hz), 0.98 (9H, t,
Jˆ7.7 Hz), 1.00 (9H, t, Jˆ7.9 Hz), 1.74±1.81 (4H, m),
2.05 (3H, d, Jˆ0.9 Hz), 2.18 (3H, d, Jˆ0.7 Hz), 2.67±
2.82 (4H, m), 5.26 (1H, d, Jˆ 0.9 Hz), 5.79 (1H, d,
Jˆ0.7 Hz), 6.88 (1H, br d, Jˆ7.5 Hz), 6.95 (1H, br d,
Jˆ7.5 Hz), 7.01 (1H, d, Jˆ8.1 Hz), 7.05 (1H, t,
Jˆ7.5 Hz), 7.16 (1H, br s), 7.20 (1H, dd, Jˆ7.9, 2.0 Hz).
13C-NMR (100 MHz, CDCl3, mixture of isomers) d 4.85,
4.94, 7.82, 21.49, 23.20, 23.43, 23.46, 23.61, 23.91, 27.18,
29.24, 29.70, 30.07, 122.54, 122.65, 124.36, 124.99, 125.08,
125.97, 127.39, 128.69, 132.58, 136.21, 136.46, 137.02,
141.71, 147.87, 152.46, 155.62. IR (neat, mixture of
isomers) 2951, 2873, 1595, 1458, 1239, 1015, 806,
758 cm21. MS (EI, 70 eV, mixture of isomers) m/z (%)
286 (15, M1), 257 (100), 189 (16), 169 (22), 115 (27),
101 (22), 87 (35), 59 (26). HRMS (EI, 70 eV, mixture of
isomers) Calcd for C19H30Si: 286.2115. Found: 286.2112
(M1). Treatment of the isomeric mixture (1:1) with RuCl3
(4 mol%) and NaIO4 (CCl4, CH3CN and H2O; rt, 2 h)7 gave
5-acetyl-1,2,3,4-tetrahydronaphthalene (43%) and 6-acetyl-
1,2,3,4-tetrahydronaphthalene (42%). 5-Acetyl-1,2,3,4-
1.9. Reaction of 1,2-undecadiene (8) and p-xylene
Under an argon atmosphere, to a stirred solution of p-xylene
(0.32 ml, 2.5 mmol) in CH2Cl2 (3.75 mL) was added a solu-
tion of GaCl3 (1.0 M in methylcyclohexane, 0.75 ml) at
2788C. Then, 8 (76 mg, 0.50 mmol) in CH2Cl2 (0.5 mL)
was added, and after 5 min methymagnesium bromide
(0.94 M in THF, 2.7 mL) was added. The mixture was
warmed to 08C, and stirring was continued for another
30 min at this temperature. The reaction was quenched by
adding aqueous NH4Cl. The organic layer was separated,
dried over MgSO4, and concentrated. The residue was puri-
®ed by GPC to give a mixture of products (70 mg, 54%)
containing (E)-9 (XˆH) (21%), (Z)-9 (XˆH) (18%), and
1
(E)-10 (15%). The yields were determined by H-NMR.
The stereochemistry was determined by NOE. (E)-9
(XˆH): 1H-NMR (400 MHz, CDCl3) d 0.88 (3H, t,
Jˆ7.0 Hz), 1.24±1.44 (12H, m), 2.00 (2H, q, Jˆ7.0 Hz),
2.24 (3H, s), 2.29 (3H, s), 3.26 (2H, d, Jˆ6.4 Hz), 5.37±
5.55 (2H, m), 6.92 (1H, br d, Jˆ 7.9 Hz), 6.94 (1H, br s),
7.01 (1H, d, Jˆ7.6 Hz). 13C-NMR (100 MHz, CDCl3) d
14.26, 18.99, 21.08, 22.81, 29.33, 29.42, 29.59, 29.62,
31.99, 32.67, 36.70, 126.54, 127.79, 129.59, 129.82,
131.72, 132.91, 135.14, 138.78. IR (neat) 2955, 2925,
2854, 1615, 1504, 1458, 1377, 968, 807 cm21. MS (EI,
70 eV) m/z (%) 258 (31, M1), 159 (11), 145 (100), 132
(61), 119 (68), 105 (23), 91 (22). HRMS (EI, 70 eV)
Calcd for C19H30: 258.2346. Found: 258.2342 (M1). (Z)-9
1
tetrahydronaphthalene: H-NMR (400 MHz, CDCl3) d
1.74±1.80 (4H, m), 2.55 (3H, s), 2.79±2.84 (2H, m),
2.92±2.98 (2H, m), 7.15 (1H, t, Jˆ7.4 Hz), 7.19 (1H, d,
Jˆ7.8 Hz), 7.43 (1H, dd, Jˆ7.8, 1.6 Hz). 13C-NMR
(100 MHz, CDCl3) d 22.57, 23.24, 27.81, 30.26, 30.31,
124.81, 126.12, 132.41, 136.59, 138.46, 138.51, 202.67.
IR (neat) 2929, 2857, 1683, 1450, 1354, 1259, 1122,
776 cm21. MS (EI, 70 eV) m/z (%) 174 (62, M1), 159
(100), 131 (71), 91 (44). HRMS (EI, 70 eV) Calcd for
C12H14O: 174.1044. Found: 174.1049 (M1). 6-Acetyl-
1,2,3,4-tetrahydronaphthalene: 1H-NMR (400 MHz,
CDCl3) d 1.79±1.84 (4H, m), 2.57 (3H, s), 2.78±2.84
(4H, m), 7.14 (1H, d, Jˆ8.4 Hz), 7.64±7.69 (1H, m). 13C-
NMR (100 MHz, CDCl3) d 22.94, 23.08, 26.65, 29.47,
29.73, 125.27, 129.06, 129.15, 134.54, 137.24, 143.00,
197.88. IR (neat) n/cm21 2930, 2857, 1682, 1605, 1416,
1357, 1270, 830 cm21. MS (EI, 70 eV) m/z (%) 174 (43,
1
(XˆH): H-NMR (400 MHz, CDCl3) d 0.88 (3H, t, Jˆ
7.0 Hz), 1.24±1.44 (12H, m), 2.14 (2H, q, Jˆ7.2 Hz),
2.25 (3H, s), 2.29 (3H, s), 3.32 (2H, d, Jˆ5.9 Hz), 5.41±
5.54 (2H, m), 6.92 (1H, br d, Jˆ7.5 Hz), 6.96 (1H, br s),
7.02 (1H, d, Jˆ7.7 Hz). 13C-NMR (100 MHz, CDCl3) d
14.26, 19.11, 21.10, 22.82, 27.47, 29.44, 29.50, 29.65,
29.77, 31.34, 32.01, 126.48, 127.35, 129.26, 129.81,

832
Y. Kido et al. / Tetrahedron 57 (2001) 827±833
130.76, 132.79, 135.22, 139.05. IR (neat) 2955, 2925, 2854,
1615, 1503, 1458, 1377, 807 cm21. MS (EI, 70 eV) m/z (%)
258 (31, M1), 159 (10), 145 (100), 132 (68), 119 (89), 105
(27), 91 (29). HRMS (EI, 70 eV) Calcd for C19H30:
258.2346. Found: 258.2336 (M1). (E)-10: 1H-NMR
(400 MHz, CDCl3) d 0.89 (3H, t, Jˆ7.0 Hz), 1.20±1.48
(12H, m), 1.89 (3H, dt, Jˆ1.5, 0.7 Hz), 2.14 (2H, q,
Jˆ6.8 Hz), 2.22 (3H, s), 2.29 (3H, s), 5.26 (1H, tq, Jˆ7.1,
1.5 Hz), 6.88 (1H, br s), 6.94 (1H, br d, Jˆ7.9 Hz), 7.03
(1H, d, Jˆ7.7 Hz). 13C-NMR (100 MHz, CDCl3) d 14.26,
18.06, 19.50, 21.02, 22.82, 28.37, 29.46 (2 carbons), 29.66,
29.71, 32.02, 126.87, 128.88, 129.49, 129.75, 131.48,
134.69, 135.71, 145.57. IR (neat) 2925, 2854, 1497, 1457,
1376, 808 cm21. MS (EI, 70 eV) m/z (%) 258 (39, M1), 243
(22), 159 (100), 146 (56), 133 (31), 119 (26). HRMS (EI,
70 eV) Calcd for C19H30: 258.2346. Found: 258.2356 (M1).
compound (E)-9 (XˆI) was converted to (Z)-9 (XˆH) as
above.
1.11. Deuteration experiment
Under an argon atmosphere, to a stirred solution of p-xylene
(0.64 mL, 5.0 mmol) in CH2Cl2 (3.0 mL) was added a solu-
tion of GaCl3 (1.0 M in methylcyclohexane, 1.0 mL) at
2788C. Then, 8 (152 mg, 1.0 mmol) in CH2Cl2 (1.0 mL)
was added, and after 5 min methymagnesium bromide
(0.94 M in THF, 2.7 mL) was added. The mixture was
warmed to 08C, and stirred for a further 30 min at this
temperature. The reaction was quenched by adding D2O
(3 mL). The organic materials were extracted with hexane,
dried over MgSO4, and concentrated. The residue was puri-
®ed by GPC to give a mixture of isomers (77 mg, 30%)
containing 9 (XˆD) and (E)-10 in a 4:1 ratio. The mixture
was treated with excess O3 in CH2Cl2-MeOH (3:2) at
2788C, and NaBH4 (190 mg, 5 mmol) at 2788C to r.t. to
give 2-(2,5-dimethylphenyl)ethanol (22 mg, 68 % deutera-
tion at 1-position), 1-(2,5-dimethylphenyl)ethanol (4 mg, no
deuteration), and 1-nonanol (26 mg, no deuteration). The
deuteration ratio was determined by D-NMR.
1.10. Iodination
Under an argon atmosphere, to a stirred solution of p-xylene
(0.32 mL, 2.5 mmol) in CH2Cl2 (3.75 mL) was added a
solution of GaCl3 (1.0 M in methylcyclohexane, 0.75 mL)
at 2788C. Then, 8 (76 mg, 0.50 mmol) in CH2Cl2 (0.5 mL)
was added, and after 5 min methylithium (1.14 M in Et2O,
2.1 mL) was added. The mixture was stirred for another
30 min at this temperature. Iodine (1.27 g, 5 mmol) in
THF (5 mL) was added and, after being warmed to room
temperature, stirring was continued for 30 min. The reaction
was quenched by adding sat. aqueous Na2SO3. The organic
layer was separated, dried over MgSO4, and concentrated.
The residue was puri®ed by GPC to give a product (77 mg,
45%), which contains (E)-9 (XˆI) (13%), (Z)-9 (XˆI)
(15%), (E)-10 (12%), and 9 (XˆH) (5%). The yields were
1.12. 1-(2-Triethylsilylethyl)-2,4-dimethylbenzene (13)
Under an argon atmosphere, to a stirred solution of
m-xylene (2.5 mL, 20 mmol) in CH2Cl2 (9 mL) was added
a 1.0 M solution of GaCl3 in methylcyclohexane (2 mL) at
2908C. Then, triethylsilylethene (12) (142 mg, 1.0 mmol)
in CH2Cl2 (1 mL) was added. After being stirred for 30 min
at this temperature, methyllithium (4 mmol) in ether
(3.6 mL) was added. Water was added, and the mixture
was extracted with hexane. The organic layer was dried
over MgSO4, and concentrated. Silica gel ¯ash chroma-
tography gave 13 (18 mg, 7%). 1H-NMR (400 MHz,
CDCl3) d 0.58 (6H, q, Jˆ8.0 Hz), 0.78±0.83 (2H, m),
0.98 (9H, t, Jˆ8.0 Hz), 2.27 (3H, s), 2.29 (3H, s), 2.52±
2.56 (2H, m), 6.95 (1H, d, Jˆ6.0 Hz), 6.96 (1H, s), 7.06
(1H, d, Jˆ8.0 Hz). 13C-NMR (100 MHz, CDCl3) d 3.45,
7.64, 12.86, 19.17, 20.99, 27.07, 126.51, 127.74, 130.79,
134.80, 134.90, 140.63. IR (neat) 2952, 2875, 1504, 1457,
1416, 1238, 1173, 1015, 824, 784, 731 cm21. MS (EI,
70 eV) m/z (%) 248 (9, M1), 219 (100), 191 (39), 163
(32), 135 (9), 115 (10), 87 (58), 59 (36). HRMS (EI,
70 eV) Calcd for C16H28Si: 248.1959. Found: 248.1966
(M1).
1
determined by H-NMR. The stereochemistry was deter-
mined by NOE. The authentic samples were obtained by
¯ash column chromatography on silica gel. (Z)-9 (XˆI):
1H-NMR (400 MHz, CDCl3) d 0.88 (3H, t, Jˆ6.8 Hz),
1.20±1.42 (12H, m), 2.12 (2H, q, Jˆ 7.2 Hz), 2.22 (3H,
s), 2.30 (3H, s), 3.79 (2H, s), 5.32 (1H, tt, Jˆ6.8, 1.1 Hz),
6.95 (1H, br s), 6.98 (1H, br d, Jˆ 7.9 Hz), 7.04 (1H, d,
Jˆ7.7 Hz). 13C-NMR (100 MHz, CDCl3) d 14.26, 19.08,
21.08, 22.80, 28.43, 29.27, 29.35, 29.52, 31.96, 36.56,
49.37, 105.92, 127.45, 130.02, 130.55, 133.37, 135.16,
135.83, 136.78. IR (neat) 2923, 2854, 1503, 1457, 1377,
809 cm21. MS (EI, 70 eV) m/z (%) 384 (21, M1), 257 (8),
159 (16), 145 (53), 131 (25), 119 (100). HRMS (EI, 70 eV)
Calcd for C19H29I: 384.1311. Found: 384.1310 (M1). This
compound (Z)-9 (XˆI) (15 mg, 40 mmol) was treated with
t-BuLi (1.5 M in pentane, 0.03 mL) in Et2O at 2908C
followed by water giving (E)-9 (XˆH) (7 mg, 67%). (E)-9
(XˆI): 1H-NMR (400 MHz, CDCl3) d 0.88 (3H, t,
Jˆ6.8 Hz), 1.20±1.44 (12H, m), 2.14 (2H, q, Jˆ7.6 Hz),
2.23 (3H, s), 2.31 (3H, s), 3.71 (2H, s), 6.40 (1H, t,
Jˆ7.2 Hz), 6.95 (1H, br s), 6.98 (1H, br d, Jˆ7.6 Hz),
7.04 (1H, d, Jˆ7.6 Hz). 13C-NMR (100 MHz, CDCl3) d
14.25, 19.31, 21.20, 22.78, 29.13, 29.30, 29.34, 29.50,
31.27, 31.95, 41.51, 99.65, 127.21, 129.25, 129.92,
133.09, 135.20, 136.08, 142.83. IR (neat) 2924, 2854,
1616, 1503, 1457, 1377, 808 cm21. MS (EI, 70 eV) m/z
(%) 384 (53, M1), 257 (8), 159 (15), 145 (42), 131
(18), 119 (100), 106 (85). HRMS (EI, 70 eV) Calcd
for C19H29I: 384.1311. Found: 384.1306 (M1). This
1.13. Reaction of p-xylene and 1-hexene (14)
Under an argon atmosphere, to a stirred solution of p-xylene
(2.5 mL, 20 mmol) in CH2Cl2 (10 mL) was added a 1.0 M
solution of GaCl3 in methylcyclohexane (0.1 mL) at 2508C.
Then, 14 (0.13 mL, 1.0 mmol) was added, and the mixture
was stirred for 1 h at this temperature. THF (4 mL) was
added, and stirring was continued for 30 min. Then, water
was added, and the organic materials were extracted with
hexane. The organic layer was dried over MgSO4, and
concentrated. Silica gel chromatography and GPC gave
1-(2-hexyl)-2,5-dimethylbenzene (15) (40 mg, 21%) and
1-(3-hexyl)-2,5-dimethylbenzene (16) (35 mg, 18%). 15:
1H-NMR (400 MHz, CDCl3) d 0.87 (3H, t, Jˆ7.2 Hz),
1.18 (3H, d, Jˆ6.8 Hz), 1.25 (6H, m), 2.27 (3H, s), 2.31

Y. Kido et al. / Tetrahedron 57 (2001) 827±833
833
(3H, s), 2.91 (1H, q, Jˆ6.8 Hz), 6.75 (1H, d, Jˆ7.6 Hz),
Acknowledgements
6.86 (1H, s), 6.88 (1H, d, Jˆ7.6 Hz). 13C-NMR (100
MHz, CDCl3) d 14.22, 19.24, 21.35, 21.68, 23.02, 30.16,
34.48, 37.71, 125.86, 125.92, 129.86, 131.95, 135.19,
145.81. IR (neat) 2958, 2927, 2858, 1503, 1457, 806,
469 cm21. MS (EI, 70 eV) m/z (%) 190 (17, M1), 133
(100), 119 (13), 105 (5), 57 (12). HRMS (EI, 70 eV)
Calcd. for C14H22: 190.1720. Found: 190.1730 (M1). 16:
1H-NMR (400 MHz, CDCl3) d 0.78 (3H, t, Jˆ7.4 Hz),
0.85 (3H, t, Jˆ7.4 Hz), 1.11±1.31 (2H, m), 1.47±1.71
(4H, m), 2.26 (3H, s), 2.30 (3H, s), 2.71±2.79 (1H, m),
6.87 (1H, dd, Jˆ7.6, 1.6 Hz), 6.94 (1H, s), 7.00 (1H, d,
Jˆ7.6 Hz). 13C-NMR (100 MHz, CDCl3) d 12.25, 14.51,
19.69, 20.83, 21.36, 29.63, 38.87, 41.57, 125.91, 126.25,
129.85, 132.94, 135.02, 144.07. IR (neat) 2957, 2929,
2871, 1503, 1457, 879, 806 cm21. MS (EI, 70 eV) m/z (%)
190 (28, M1), 161 (19), 147 (44), 133 (19), 119 (100), 105
(6). HRMS (EI, 70 eV) Calcd for C14H22: 190.1720. Found:
190.1719 (M1).
This work was supported by grants from the Japan Society
of Promotion of Science, Ministry of Education, Science,
Sport and Culture, Japan, and the Naito Science Foundation.
A fellowship to Y. K. from the Japan Society of Promotion
of Science for young Japanese scientists is gratefully
acknowledged.
References
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Wiley & Sons, 1973. (b) Taylor, R. Electrophilic Aromatic
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2. (a) Yamaguchi, M.; Kido, Y.; Hayashi, A.; Hirama, M.
Angew. Chem., Int. Ed. Engl. 1997, 36, 1313. (b) Kido, Y.;
Yoshimura, S.; Yamaguchi, M.; Uchimaru, T. Bull. Chem.
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1.14. NMR experiment
Under an argon atmosphere, a solution of 1 (46 mg,
0.30 mmol) in CD2Cl2 (0.3 mL) was cooled to 2858C in
an NMR sample tube. A solution of GaCl3 (1.0 M in
CD2Cl2, 0.3 mL) was then added. The mixture was gently
shaken at this temperature until white crystals of GaCl3
disappeared, and the solution turned orange. 1H-NMR
(400 MHz, CD2Cl2, 2858C)d 0.6±0.8 (m), 0.9±1.0 (m),
4.52 (2H, br s), 5.5±6.2 (1H, br). 13C-NMR (100 MHz,
CD2Cl2) d 2.55, 5.56, 5.99, 74.55. A solution of 1 (31 mg,
0.20 mmol) in CD2Cl2 (0.2 mL) was cooled to 2858C in an
NMR sample tube. A solution of GaCl3 (1.0 M in CD2Cl2,
0.4 mL) was then added. The mixture was gently shaken at
this temperature until white crystals of GaCl3 disappeared,
and the solution turned orange. 1H-NMR (400 MHz,
CD2Cl2, 2858C) d 0.7±1.0 (m), 4.49 (2H, s), 6.12 (1H, s).
13C-NMR (100 MHz, CD2Cl2) d 3.32, 5.53, 5.58, 5.92,
72.15, 222.33.
4. A review for the electrophilic addition reactions to allenes:
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