Ortho-vinylation reaction of phenols with ethyne

Article abstract of DOI:10.1021/jo980785f

Phenols were vinylated at the ortho-position with ethyne in the presence of SnCl₄-Bu₃N reagent. The reaction was applicable to phenols possessing either electron-donating or electron-withdrawing groups. 2,6-Divinylphenols were synthe

Full text of DOI:10.1021/jo980785f

7298
J . Org. Chem. 1998, 63, 7298-7305
Or th o-Vin yla tion Rea ction of P h en ols w ith Eth yn e
Masahiko Yamaguchi,* Mieko Arisawa, Kenji Omata,† Kuninobu Kabuto,†
Masahiro Hirama,† and Tadafumi Uchimaru‡
Faculty of Pharmaceutical Sciences, and Department of Chemistry, Graduate School of Science,
Tohoku University, Aoba, Sendai 980-8578, J apan, and Department of Physical Chemistry,
National Institute of Materials and Chemical Research Agency of Industrial Science and Technology,
MITI, Tsukuba, Ibaraki 305-8565, J apan
Received April 28, 1998
Phenols were vinylated at the ortho-position with ethyne in the presence of SnCl4-Bu3N reagent.
The reaction was applicable to phenols possessing either electron-donating or electron-withdrawing
groups. 2,6-Divinylphenols were synthesized under modified conditions. A reaction mechanism
involving carbostannylation of alkynyltin and phenoxytin was discussed.
Sch em e 1
In 1908, pure o-vinylphenol was synthesized for the
first time by decarboxylation of o-hydroxycinnamic acid.1
Since then, a number of methods were developed for the
synthesis of vinylphenols. Electrophilic acylation of
phenol followed by reduction and dehydration was em-
ployed in the commercial production of p-vinylphenol by
Maruzen Petrochemicals Co.2 Another method which
utilized benzylic oxidation of ethylphenol was reported.3
Halophenol derivatives could be vinylated by the Heck
reaction.4 Pyrolysis of heterocyclic compounds was re-
ported.5 All these syntheses, however, employed stepwise
transformations starting from phenol.
The direct vinylation of phenol with ethyne, vinyl
halides, oxirane, vinyl acetate, etc., is potentially the most
straightforward method. However, many attempts of the
electrophilic substitution failed giving 1,1-diarylethanes
as well as mixtures of oligomeric and polymeric sub-
stances (Scheme 1).6 Although some reports claimed
formation of vinylphenols,7 these results could not be
reproduced.8 Formation of 1,1-diarylethane suggested
the generation of the vinylphenol in the reaction mixture
which appeared not to be stable under the reaction
conditions. Rapid protonation takes place giving benzylic
cation, which reacts with another molecule of phenol.
Protonation of vinylphenol must be much faster than the
protonation of the vinylating reagents such as ethyne or
vinyl halide. Attempts at phenol vinylation under basic
conditions also gave polymeric substances.9
Poly(vinylphenol)s are attracting much attention in the
field of material sciences.10 Many applications were
examined including photoresist, antibacterial polymer,
nonlinear optic material, liquid crystal, cross-linking
agent, etc. It should be emphasized that the protected
poly(p-vinylphenol) is the photoresist material for the
production of the next generation DRAM (dynamic
random access memory). Despite such importance, a
very small amount of work has been done on the
chemistry of hydroxystyrenes other than the three iso-
mers of vinylphenol, which may be due to their unavail-
ability. The conventional synthesis of vinylphenols as
mentioned above required multistep transformations
from phenol, which were not suitable for the preparation
of functionalized derivatives. We previously reported a
novel method which converts phenols to o-vinylphenols
using ethyne as the vinylating reagent (Scheme 2).11
Described here are the details of this reaction.
† Department of Chemistry, Tohoku University.
‡ MITI.
(1) Fries, K.; Fickewirth, G. Chem. Ber. 1908, 41, 367.
(2) Corson, B. B.; Heinzelman, W. J .; Schwartzman, L. H.; Tief-
enthal, H. E.; Lokken, R. J .; Nickels, J . E.; Atwood, G. R.; Pavlik, F. J .
J . Org. Chem. 1958, 23, 544. Everhart, E. T.; Craig, J . C. J . Chem.
Soc., Perkin Trans. 1 1991, 1701.
(3) Emerson, W. S.; Heyd, J . W.; Lucas, V. E.; Cook, W. B.; Owens,
G. R.; Shortridge, R. W. J . Am. Chem. Soc. 1946, 68, 1665.
(4) Rollin, Y.; Meyer, G.; Troupel, M.; Fauvarque, J .-F.; Perichon,
J . J . Chem. Soc., Chem. Commun. 1983, 793.
Sch em e 2
(5) Gripenberg, J .; Hase, T. Acta Chem. Scand. 1956, 20, 1561. Also
see, Bu¨chi, G.; Burgess, E. M. J . Am. Chem. Soc. 1962, 84, 3104.
(6) Vaiser, V. L. Doklady Akad. Nauk SSSR 1950, 74, 57; Chem
Abstr. 1951, 45, 3827h. Vaiser, V. L.; Polikarpova, A. M. Doklady Akad.
Nauk SSSR 1954, 97, 671; Chem Abstr. 1955, 49, 10242g.
(7) Flood, S. A.; Nieuwland, J . A. J . Am. Chem. Soc. 1928, 50, 2566.
Smith, R. A.; Niederl, J . B. J . Am. Chem. Soc. 1931, 53, 806. Niederl,
J . B.; Smith, R. A.; McGreal, M. E. J . Am. Chem. Soc. 1931, 53, 3390.
(8) Bader, A. R. J . Am. Chem. Soc. 1955, 77, 4155. Williams, J . L.
R.; Borden, D. G.; Laakso, T. M. J . Org. Chem. 1956, 21, 1461. Dale,
W. J .; Hennis, H. E. J . Am. Chem. Soc. 1958, 80, 3645. Sovish, R. C.
J . Org. Chem. 1959, 24, 1345.
(9) Karpukhin, P. P.; Slachinskaya, A. I.; Sergeeva, L. I.; Spengler,
V. M. Vestn. Khar’kov. Politekh. Inst. 1971, 60, 50; Chem Abstr. 1973,
79, 115905x. Reppe, W. Ann. 1956, 601, 81. Karpukhin reported the
synthesis of vinylphenol under basic conditions using pressurized
ethyne, while Reppe reported polymerization.
(10) For examples, see: Fre´chet, J . M. J .; Tessier, T. G.; Willson, C.
G.; Ito, H. Macromolecules 1985, 18, 317. Marks, T. J .; Ratner, M. A.
Angew. Chem., Int. Ed. Engl. 1995, 34, 155.
S0022-3263(98)00785-3 CCC: $15.00 © 1998 American Chemical Society
Published on Web 09/19/1998

Ortho-Vinylation Reaction of Phenols with Ethyne
J . Org. Chem., Vol. 63, No. 21, 1998 7299
Ta ble 1. Vin yla tion of P h en ols w ith Eth yn e
conditions
entry
R1
R2
R3
R4
vinylationa
workupb
yield/%
ratioc
1
2
3
4
5
6
7
8
9
H
H
H
H
Me
t-Bu
H
H
H
H
H
H
H
H
H
H
H
MeO
t-BuMe2SiO
H
H
H
H
H
H
H
H
H
H
H
H
CN
F
CF3
H
H
H
H
H
H
H
Me
t-Bu
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
A
A
A
A
A
A
A
B
A
A
A
A
B
A
B
A
A
I
I
I
I
I
I
I
I
80
83
83
83
90
91
75
78
38
83
79
66
83
76
87
86
76
81
62
48
92
71
86
76
90
69
58
41d
74
73
67
79
82
52
41d
68
78
Me
t-Bu
Ph
H
H
H
1:1
1:1
H
CHdCHCHdCH
I
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
H
H
H
H
H
H
H
H
MeO
t-BuMe2SiO
Et3SiO
CH3COO
t-BuCOO
PhCH2OCOO
p-TolSO3
CF3SO3
H
H
H
H
H
H
H
H
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
III
I
H
H
MeO
t-BuPh2SiO
CH3COO
t-BuCOO
CF3SO3
t-BuCOO
t-BuMe2SiO
Et3SiO
H
H
H
H
H
H
H
NO2
F
3:1
3:1
3:1
3:1
3:1
t-BuCOO
t-BuMe2SiO
Et3SiO
H
H
NO2
F
CF3
CN
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
I
III
III
III
I
III
I
2:1
4:1
1:1
H
H
I
III
CF3
H
a
b
Conditions of vinylation: A: 60 °C, 1 h. B: 90 °C, 30 min. C: 60 °C, 30 min. Basic workup conditions. I: 2 M NaOH aq, reflux, 1
h. II: K2CO3, methanol, reflux 30 min. III: K2CO3, methanol, room temperature, 1 h. c Ratio of 6-vinylated and 2-vinylated products
d
formed in the reaction of 3-substituted phenol. Isolated without acetylation.
The following procedures were employed for the vinyl-
ation of phenol with gaseous ethyne giving o-vinylphenol.
SnCl4 and Bu3N were added to a chlorobenzene solution
of ethyne to generate stannylacetylene, which was the
active vinylating species of the present reaction. Then,
another portion of SnCl4 and Bu3N was added followed
by phenol. The second tin reagent was used to generate
phenoxytin, the other species responsible for the C-C
bond formation. Then, the mixture was heated at 60 °C
for 1 h to couple the organotin compounds. The new
organotin thus generated was treated with aqueous
NaOH or K2CO3 in methanol at reflux for protodestan-
nylation. If the alkaline treatment was not sufficiently
done, the yield decreased. Since o-vinylphenol was
relatively unstable especially in the presence of small
amounts of acid, the product was isolated after acetyl-
ation (Table 1, entry 1). Introduction of the electron-
withdrawing protecting group improved the stability.
Acetylated o-vinylphenol was distilled in the presence of
radical inhibitor. The vinylation reaction could be con-
ducted in 10-g scale using these protocols. There are
several notable aspects in the reaction procedures. The
ethyne was introduced to chlorobenzene at -50 °C before
the addition of the tin reagent and was then stopped. The
gas need not be bubbled throughout the reaction due to
the high efficiency of the C-C bond formation. The
vinylation proceeded rapidly at 60 °C in solvents such
as chlorobenzene or 1,2-dichloroethane.
Vinylation of the three isomers of cresol and tert-
butylphenol represents the reaction of alkyl-substituted
phenols. Ortho- and para-substituted phenols gave
expected mono-vinylated products in high yields (entries
2-6). As for the meta-substituted phenols, a mixture of
regioisomers was obtained in comparable amounts, which
was more easily separated by chromatography after
deacetylation (entries 7 and 8). Notably, the bulky ortho-
substituent did not interfere with the vinylation as
indicated by the reaction of o-tert-butylphenol (entry 6).
Furthermore, a considerable amount of vinylation took
place at the sterically congested 2-position of m-tert-
(11) Yamaguchi, M.; Hayashi, A.; Hirama, M. J . Am. Chem. Soc.
1995, 117, 1151.

7300 J . Org. Chem., Vol. 63, No. 21, 1998
Yamaguchi et al.
Sch em e 3
butylphenol (entry 8). A polycyclic aromatic compound
such as 2-naphthol was also vinylated, although with
lower yield because of decomposition (entry 9).
Styrenes possessing electron-donating groups, espe-
cially at the ortho- and para-position, were known to be
sensitive to acid and oxygen and to polymerize readily.12
The vinylation reaction of benzenepolyol derivatives
therefore could reveal the scope and the limitation of the
present method. Various monoprotected 1,4-benzenediols
were subjected to vinylation (entries 10-17). Methoxy,
tert-butyldimethylsilyloxy, benzyloxycarbonyloxy, piv-
aloyloxy, and sufonyloxy groups were unaffected, and
2-ethenyl-1,4-benzenediols with two hydroxy groups dif-
ferentiated were obtained in high yields. The reactions
were worked up with K2CO3 in methanol at reflux to
avoid deprotection. Although acetate survived the vinyl-
ation reaction conditions, deacetylation took place during
the alkaline workup (entry 13). The diacetylated product
was obtained by the reacetylation of 2-ethenyl-1,4-
benzenediol. Thus, the present vinylation tolerated
various functionalities, and SnCl4-Bu3N conditions turned
out to be fairly mild. However, trityl and 2H-tetrahy-
dropyran-2-yl derivatives decomposed during the vinyl-
ation. Vinylation of 1,2-benzenediol derivatives also took
place (entries 18 and 19). Attempted vinylation of 1,4-
benzenediol and 1,3-benzenediol failed, giving polymeric
substances.
Sch em e 4
Vinylphenols synthesized from monoprotected 1,3-
benzenediol were expected to be less stable compared to
the vinylated 1,4- and 1,2-benzenediol derivatives, since
the former compounds possessed electron-donating groups
at both ortho- and para-positions of the vinyl group. We
were therefore pleased to find that m-methoxyphenol
could be vinylated by the present methodology (entry 20).
The reaction, however, competed with the decomposition
reaction and must be stopped before the consumption of
the starting material. The yield was improved by chang-
ing the protecting group to an acyl, silyl, or sulfonyl group
(entries 21-24). Irrespective of the protecting groups,
approximately 3:1 mixtures of the regioisomers were
obtained. The vinylation took place at the less-hindered
site predominantly. Even bis-silylated and bis-pivalated
1,3,5-benzenetriols could be vinylated successfully (en-
tries 25-27).
The protecting groups were next removed from these
polyhydroxystyrene derivatives (Scheme 3). 2-Ethenyl-
1,4-benzenediol (1) was synthesized by deprotection of
the diacetate with K2CO3-methanol. tert-Butyldimethyl-
silyl and acetate groups were removed simultaneously
with K2CO3-KF as shown in the synthesis of 3-ethenyl-
1,2-benzenediol (2). Two isomers formed by the reaction
of m-pivaloxyphenols were separated by chromatography
and were subjected to the deprotection with butyllithium
in THF at room temperature. 4-Ethenyl-1,3-benzenediol
(3) and 2-ethenyl-1,3-benzenediol (4) were more sensitive
than 1 and 2 to acid and oxygen. These reactions
therefore were conducted using the freeze-evacuated
solvents and were quenched with buffer. Since contact
of 3 and 4 with silica gel caused polymerization, they
were purified by reverse phase chromatography. While
dihydroxystyrenes 1-3 were obtained in crystalline form,
the aqueous solution of 4 could not be concentrated to
dryness without polymerization even using freeze-drying
techniques. Synthesis of 1 was previously reported which
used decarboxylation of the corresponding hydroxy-
cinnamic acid.13 It employed a lengthy transformation
from chromone and suffered from low yields at the final
stages. Compounds 2,14 3,15 and 4 have not been pre-
pared chemically, making this new methodology useful.
The present vinylation was next applied to phenols
with electron-withdrawing groups (Table 1, entries 28-
37). Phenols possessing a fluoro, trifluoromethyl, and
cyano group were converted to the corresponding vinyl-
phenols in satisfactory yields. A higher reaction tem-
perature was required for nitrophenols, and vinylated
products could be isolated without acetylation (entries
28 and 35). Vinylated products obtained from o- and
p-(trifluoromethyl)phenol decomposed when treated with
aqueous NaOH under reflux, giving carboxylic acid
derivatives, while the meta-derivative was not affected.
It may be due to the â-elimination reaction that generates
quinoid compounds. To avoid such decomposition, the
reactions of trifluoromethylphenols and cyanophenols
were worked up with K2CO3 in methanol at room tem-
perature (entries 30-32, 34, and 37). The vinylation and
hydrolysis of o-(trifluoromethyl)phenol gave vinylsalicylic
acid (Scheme 4). It is interesting from a synthetic point
of view, since the compound could not be obtained by the
(13) Updegraff, I. H.; Cassidy, H. G. J . Am. Chem. Soc. 1949, 71,
407. Iwabuchi, S.; Ueda, M.; Kobayashi, M.; Kojima, K. Polymer J .
1974, 6, 185.
(14) 3-Ethenyl-1,2-benzenediol was obtained as a microbial metabo-
lite of styrene. Warhurst, A. M.; Clarke, K. F.; Hill, R. A.; Holt, R. A.;
Fewson, C. A. Appl. Environ. Microbiol. 1994, 60, 1137.
(15) Synthesis of 4-ethenyl-1,3-benzenediol was noted without
structure determination in ref 7. It may be unlikely if one looks at the
results of many attempted Friedel-Crafts vinylation of phenol.
(12) Overberger, C. G.; Arond, L. H.; Tanner, D.; Taylor, J . J .; Alfrey,
T., J r. J . Am. Chem. Soc. 1952, 74, 4848. Okamoto, Y.; Brown, H. C.
J . Org. Chem. 1957, 22, 485. Mayen, M.; Marechal, E. Bull. Soc. Chim.
Fr. 1972, 4662.

Ortho-Vinylation Reaction of Phenols with Ethyne
J . Org. Chem., Vol. 63, No. 21, 1998 7301
Ta ble 2. 2,6-Divin yla tion of P h en ols w ith Eth yn e
Sch em e 5
con-
yield/
%
ratiob
divinyl:monovinyl
entry
X
ditionsa
1
2
3
4
5
6
7
8
9
10
11
12
13
H
I
I
I
I
II
II
I
II
I
66
69
71
77
73
72
80
87
75
25
48
49
41
5:1
5:1
5:1
4-Me
4-(t-Bu)
4-MeO
4-(t-BuMe2SiO)
4-(t-BuPh2SiO)
4-Ph
4-(t-BuCOO)
3-Me
3-MeO
g10:1
6:1
g10:1
1:1
1:3
4:1c
I
g10:1
g10:1
g10:1
8:1
3-(t-BuMe2SiO)
3-(t-BuPh2SiO)
3,5-bis(t-BuMe2SiO)
III
III
III
critical to obtain the divinylphenol predominantly. When
it was changed, for example, to 2 + 2, 2 + 5, 5 + 5, or 5
+ 0 mol equiv, 1:1 mixtures of mono- and divinylated
products were formed. Addition of an excess of tin
reagent and ethyne to these reaction mixtures did not
improve the ratio. Use of a large excess of reagent (12
+ 0 mol equiv) gave mono-vinylated product predomi-
nantly in a ratio of 1:6. Treatment of isolated 4-tert-
butyl-2-vinylphenol with ethyne under these conditions
resulted in decomposition. The first and the second
vinylation apparently are not independent chemical
processes, and the reaction mechanism of the divinylation
is rather complex.
a
Conditions of workup. I: 2 M aq NaOH, ethanol, 100 °C, 2 h.
II: K2CO3, methanol, room temperature, 1 h. III: K2CO3, THF
b
water, room temperature, 1 h. Ratio of mono-vinylated phenol
and divinylated phenol. c Mono-vinylated product is a 1:1 mixture
of 2-vinyl-5-methylphenyl acetate and 2-vinyl-3-methylphenyl ace-
tate.
vinylation of the salicylic acid ester. Hydrogen bonding
to the phenolic hydroxy group appeared to reduce the
reactivity.
It was found that the modifications of the reaction
conditions gave 2,6-divinylphenols (Table 2).16 Divinyl-
benzenes are an important class of chemicals in polymer
synthesis and organic synthesis.17,18 Their chemistry,
however, has been limited to the three isomers of
divinylbenzene,19 and very few functionalized derivatives
have been known. Divinylbenzenes were synthesized by
stepwise transformations from benzene via diethylben-
zene, dihalobenzene, diformylbenzene, etc.,20 which were
not suitable for the preparation of functionalized deriva-
tives. This synthesis therefore provided an easy access
to functionalized m-divinylbenzenes.
A reaction temperature of 100 °C was necessary to
allow the bis-vinylation to occur. A lower temperature
gave mainly mono-vinylation, and decomposition took
place at temperatures exceeding 100 °C. As mentioned
previously, sequential addition is important, and the
amount of the tin reagent (5 + 2 mol equiv) was also
Several para- and meta-substituted phenols and phenol
itself were treated with ethyne under these conditions.
Alkoxy and alkyl derivatives gave divinylphenol pre-
dominantly to exclusively. Although the reaction of
m-methoxyphenol competed with decomposition, the di-
vinylated product could still be obtained (entry 10).
p-Pivaloxyphenol and p-phenylphenol gave comparable
amounts of monovinyl and divinyl derivatives (entries 7
and 8). The divinylation was facilitated by the electron-
donating substituents on the aromatic ring. Even 3,5-
bis(silyloxy)phenol was divinylated, giving a protected
2,6-diethenyl-1,3,5-benzenetriol (entries 13). To avoid
deprotection, the reactions of silyloxyphenols and acyl-
oxyphenols were quenched with either K2CO3 in metha-
nol or K2CO3 in THF-water at room temperature. The
latter conditions were employed in the reaction of m-
(silyloxy)phenols, since alcohol addition took place to the
reactive olefin when the workup was conducted in the
presence of methanol.
(16) Preliminary report. Yamaguchi, M.; Arisawa, M.; Hirama, M.
J . Chem. Soc., Chem. Commun. 1997, 1663.
(17) For examples, see: Suzuki, M.; Lim, J .-C.; Saegusa, T. Macro-
molecules 1990, 23, 1574. Kumar, A.; Eichinger, B. E. Makromol.
Chem., Rapid Commun. 1992, 13, 311. Chujo, Y.; Tomita, I.; Kozawa,
Y.; Saegusa, T. Macromolecules 1993, 26, 2643. Thorn-Csa´nyi, E.;
Pflug, K. P. J . Mol. Cat. 1994, 90, 69.
(18) For examples, see: Liu, L.; J . Katz, T. Tetrahedron Lett. 1990,
31, 3983. Hamana, H.; Horiguchi, K.; Hagiwara, T.; Narita, T. Bull.
Chem. Soc. J pn. 1990, 63, 1884. Padias, A. B.; Tien, T.-P.; Hall, H. K.,
J r. J . Org. Chem. 1991, 56, 5540. Nishimura, J .; Horikoshi, Y.; Wada,
Y.; Takahashi, H.; Sato, M. J . Am. Chem. Soc. 1991, 113, 3485. Suzuki,
T.; Fukushima, T.; Yamashita, Y.; Miyashi, T. J . Am. Chem. Soc. 1994,
116, 2793.
(19) Separation of isomeric divinylbenzenes. Storey, B. T. J . Polym.
Sci., Part A 1965, 3, 265. Wiley, R. H.; J in, J . I.; Kamath, Y. J . Polym.
Sci., Part A-1 1968, 6, 1065.
Mixtures of divinylphenyl acetate and monovinyl-
phenyl acetate were treated with K2CO3 in methanol to
give 2,6-divinylphenol and 2-vinylphenol, which were
readily separable by silica gel chromatography. Thus,
divinylphenols were obtained from phenol, alkylphenols,
and alkoxyphenols in overall yields ranging from 40 to
60% (Scheme 5). Treatment of 4-(tert-butyldimethyl-
silyloxy)phenol with KF in methanol gave 2,6-divinyl-
1,4-benzenediol, which can be an interesting building
block for redox polymers. Despite the simple molecular
structure, most divinylphenols synthesized here, includ-
ing the parent 2,6-divinylphenol itself, were new com-
pounds.21
(20) For examples, see: J ohnston, H. W.; Williams, J . L. R. J . Am.
Chem. Soc. 1947, 69, 2065. Mitchell, R. H.; Ghose, B. N.; Williams, M.
E. Can. J . Chem. 1977, 55, 210. Plevyak, J . E.; Heck, R. F. J . Org.
Chem. 1978, 43, 2454. McKean, D. R.; Parrinello, G.; Renaldo, A. F.;
Stille, J . K. J . Org. Chem. 1987, 52, 422. Nuyken, O.; Siebzehnru¨bl,
F. Makromol. Chem. 1988, 189, 541.

7302 J . Org. Chem., Vol. 63, No. 21, 1998
Yamaguchi et al.
Sch em e 6
F igu r e 1.
Sch em e 7
presence of the ethenylphenol keto form, which can
possess allyltin structure.
To gain additional information on the carbostannyl-
ation reaction, the reactivity of substituted phenols was
compared. The rate difference was pronounced in al-
kenylation compared to vinylation probably because of
the steric reasons. m-Methoxyphenol (6), p-methoxyphe-
nol (7), phenol (8), p-cyanophenol (9), and m-cyanophenol
(10) were reacted with phenylacetylene (Scheme 7).
Alkenylation of 6 and 7 for 30 min at 60 °C gave mixtures
of mono- and divinylated products in 98% and 76% yields,
respectively. While no starting material was recovered
in the former reaction, 11% of 7 was recovered in the
latter. The vinylation rate of 8 was slightly lower than
that of 7. The vinylation of 9 and 10 did not proceed at
60 °C, and a higher temperature of 90 °C was required.
Under the same reaction conditions, the conversion was
greater for 9 than for 10. The reactivity order then was
summarized as 6 > 7 g 8 > 9 > 10 and qualitatively
correlated with the electron density at the ortho-carbon
atom. The phenol, or more precisely the phenoxytin,
appeared to behave as a nucleophile.
As for the alkynyltin, ab initio calculations23 of HCt
CSnF3 (11) showed that the â-carbon atom was less
negatively charged than the R-carbon atom (Figure 1).
In addition, the coefficients of π* orbitals of CsC triple
bond were larger at the â-carbon atom. These tendencies
were more prominent with 11 than with HCtCSnH3 (12),
which were consistent with 13C NMR chemical shifts of
the stannylated 1-alkyne. The acetylenic â-carbon of
alkynyltrichlorotin 13 derived from 1-heptyne appeared
at considerably lower field than the corresponding tri-
butyltin derivative 14. Experimentally, trialkylalkynyl-
tin and trialkylphenoxytin did not undergo carbostannyl-
ation. Thus, the electrophilic alkynyltin turned out to
The mechanism of the phenol vinylation would be
analogous to the alkenylation reaction, which we previ-
ously reported.11,22 Ethyne and phenol are converted to
trichlorostannylethyne and phenoxytin, respectively, and
the carbostannylation reaction between the organotin
compounds gives the 2-[â,â-bis(trichlorostannyl)vinyl]-
phenol derivative (Scheme 6). The reactive olefins of the
vinylphenols may be protected from oligomerization and
polymerization by bis-stannylation. Involvement of such
an intermediate was validated by deuteration experi-
ments. When the vinylation reaction of o-tert-butylphe-
nol was quenched with NaOD in D2O, both olefinic
protons were deuterated. Control experiments showed
no deuterium exchange at vinyl protons of the ethenyl-
phenol in NaOD-D2O. The alkaline workup conducted
in the present reaction protonated the carbon-tin bond
of the bis-stannyl intermediates. Relatively facile pro-
tonation of the vinylstannane may be partly due to the
(23) All calculations were carried out at RHF/LANL1MB level by
using Gaussian 92. The NBO analyses were made with respect to the
fully optimized geometries. We evaluated atomic charges and orbital
coefficients based on the NBO analyses. Gaussian 92, Revision A,
Frisch, M. J .; Trucks, G. W.; Head-Gordon, M.; Gill, P. M. W.; Wong,
M. W.; Foresman, J . B.; J ohnson, B. G.; Schlegel, H. B.; Robb, M. A.;
Replogle, E. S.; Gomperts, R.; Andres, J . L.; Raghavachari, K.; Binkley,
J . S.; Gonzalez, C.; Martin, R. L.; Fox, D. J .; Defrees, D. J .; Baker, J .;
Stewart, J . J . P.; Pople, J . A. Gaussian, Inc., Pittsburgh, PA, 1992.
(21) A patent of 4-methyl-2,6-divinylphenol appeared. Kitano, H.
J apan Pat. 74 14,319, 1974; Chem. Abstr. 1975, 82, 114031j.
(22) Also see, Yamaguchi, M.; Hayashi, A.; Hirama, M. J . Am. Chem.
Soc. 1993, 115, 3362. Hayashi, A.; Yamaguchi, M.; Hirama, M.; Kabuto,
C.; Ueno, M. Chem. Lett. 1994, 1881.

Ortho-Vinylation Reaction of Phenols with Ethyne
J . Org. Chem., Vol. 63, No. 21, 1998 7303
Sch em e 8
comitant dearomatization. The vinylating reagent ap-
pears to be strongly directed to the ortho-position. Two
possibilities were considered for the introduction of the
other ethyne unit: The Diels-Alder reaction of stannyl-
ated ethyne with 16, or the intramolecular conjugate
addition of vinyltin. Since both protons at the bridged
position of 17 were stannylated (deuterated), the former
mechanism appeared likely. The conjugate addition of
16 should give the mono-stannylated intermediate.
To summarize, various functionalized phenols were
converted to o-vinylphenol by treating with ethyne in the
presence of the SnCl4-Bu3N reagent. This reaction and
the new products obtained may find various applications
in organic chemistry and polymer chemistry.
Sch em e 9
Exp er im en ta l Section
4-Meth oxy-2-eth en yl-1-p h en yl Aceta te (synthesis in 20
mmol scale). Under an argon atmosphere, ethyne was bubbled
into a a stirred chlorobenzene (100 mL) solution of SnCl4 (9.7
mL, 80 mmol) and Bu3N (20 mL, 80 mmol) at -50 °C for 30
min. Then, p-methoxyphenol (7, 2.49 g, 20 mmol) in chloro-
benzene (2 mL) was added, and the mixture was heated at 60
°C for 1 h. K2CO3 (13.8 g) and methanol (100 mL) were added,
and refluxing was continued for another 30 min. After being
cooled to room temperature, the contents were poured into a
mixture of ether and saturated aq KHSO4. The precipitate
formed was filtered through Celite, and the organic materials
were extracted twice with ether. The combined organic layers
were washed with brine and dried over Na2SO4. Ether was
removed under reduced pressure, and acetic anhydride (20 mL)
and pyridine (20 mL) were added to the resulting chloroben-
zene solution. After the mixture was stirred for 8 h at room
temperature, saturated aq KHSO4 was added. The organic
materials were extracted twice with ethyl acetate, washed with
saturated aq NaHCO3 and brine, dried over Na2SO4, and
concentrated in vacuo. 4-Methoxy-2-vinylphenyl acetate (3.14
g, 82%) was obtained by flash chromatography (hexane:ethyl
acetate ) 50:1 to 20:1) over silica gel. 1H NMR (400 MHz,
CDCl3) δ 2.31 (3H, s), 3.81 (3H, s), 5.33 (1H, brd, J ) 11.0
Hz), 5.74 (1H, brd, J ) 17.6 Hz), 6.70 (1H, dd, J ) 17.6, 11.0
Hz), 6.82 (1H, dd, J ) 8.8, 2.9 Hz), 6.95 (1H, d, J ) 8.9 Hz),
7.06 (1H, d, J ) 2.9 Hz). 13C NMR (100 MHz, CDCl3) δ 20.8,
55.5, 110.9, 114.3, 116.5, 123.2, 130.3, 130.8, 141.7, 157.4,
be more reactive toward carbostannylation. This elec-
trophilic property is due to the inductive effect of SnCl3
group rather than the mesomeric effect since the IR
absorption of 13 appeared at a higher wavenumber than
14.
169.7. IR (neat) 1763, 922, 899, 826 cm-1
. MS (EI, 70 eV)
m/z (%) 192 (M+, 37), 150 (M+ - CH3, 100), 135 (M+ - CH2CO
- CH3, 26). HRMS (EI, 70 eV) calcd for C11H12O3: 192.0787.
Found: 192.0789 (M+).
2-Eth en yl-1-ph en yl Acetate (synthesis in 120 mmol scale).
An oven-dried, 1-L, three-necked, round-bottomed flask fitted
with a gas inlet was placed under an argon atmosphere and
charged with 1,2-dichloroethane (600 mL). After it was cooled
to -50 °C in a methanol bath, SnCl4 (30 mL, 250 mmol) and
Bu3N (60 mL, 250 mmol) were added, and acetylene gas was
introduced at -40 °C (methanol bath) for 2.5-3 h. After
bubbling was stopped, the methanol bath was removed, and
the mixture was stirred at room temperature for 30 min.
Phenol (11.8 g, 125 mmol) in 1,2-dichloroethane (20 mL), SnCl4
(30 mL), and Bu3N (60 mL) were added successively, and the
mixture was heated at 60 °C for 6 h. After being cooled to
room temperature, the mixture was poured into a 3-L, round-
bottomed flask, and stirred with aqueous 4 N sodium hydrox-
ide (1 L) and ethanol (500 mL) at room temperature overnight.
Then the reaction mixture was poured into a 5-L separating
funnel and extracted twice with diethyl ether. The organic
phase was washed twice with aqueous 2 N hydrochloric acid
(1 L). The aqueous phase was acidified by addition of aqueous
2 N hydrochloric acid (ca. 3 L) and extracted twice with diethyl
ether. The combined organic layers were dried over anhydrous
Na2SO4, filtered, and concentrated to about 500 mL under
reduced pressure. Then, pyridine (60 mL) was added to
precipitate tin salts, which were filtered through a Celite pad
(No. 545) and washed sufficiently with diethyl ether. The
The carbostannylation seems to be controlled by the
electronic nature of each tin reagent and can be envisaged
as the reaction of nucleophilic phenoxytin and electro-
philic stannylacetylenes. The regioselective â,â-bis-stan-
nyl olefin formation therefore could be explained as the
nucleophilic attack of phenoxytin at the electrophilic
â-carbon atom of the stannylacetylene (Scheme 8). We,
however, are not yet able to present the precise transition
structure of the carbostannylation reaction.
All of the above reactions took place at the ortho-
position of phenolic hydroxy group. To explore the
possibility of para-vinylation, 2,6-dimethylphenol was
vinylated using our standard conditions, which gave the
relatively unstable bicyclo[2.2.2]octane derivative 15
(Scheme 9). The structure, consisting of one molecule of
phenol and two molecules of ethyne, was determined by
2D-NMR including NOE studies, and all of the protons
were assigned unambiguously. When the reaction was
worked up with NaOD-D2O, 15-d3 was obtained, indi-
cating the presence of tris-stannylated intermediate 17.
Thus, the formation of 15 should have taken place via
16 by the ortho-vinylation of dimethylphenol with con-

7304 J . Org. Chem., Vol. 63, No. 21, 1998
Yamaguchi et al.
combined organic layers were again concentrated to about 500
mL under reduced pressure. Acetic anhydride (120 mL) and
a catalytic amount of 4-(dimethylamino)pyridine were added,
and the mixture was stirred at room temperature overnight.
Then, the mixture was poured into a 1-L separating funnel,
washed with a saturated solution of KHSO4 and NaHCO3,
dried over anhydrous Na2SO4, filtered, and concentrated under
reduced pressure. Flash short-column chromatography with
hexane:ethyl acetate ) 20:1 gave crude acetate (16 g, 80%).
Then, tert-butylhydroquinone (10 mg) was added, and distil-
lation under reduced pressure gave 2-ethenylphenyl acetate
(12-14 g, 60-70%) as a pale-yellow liquid, bp 55-65 °C/0.8
mmHg (lit.24 85 °C/1 mmHg). 1H NMR (200 MHz, CDCl3) δ
2.33 (3H, s), 5.33 (1H, dd, J ) 1.2, 11.1 Hz), 5.75 (1H, dd, J )
1.1, 17.6 Hz), 6.75 (1H, dd, J ) 11.1, 17.6 Hz), 7.04 (1H, dd, J
) 1.8, 7.5 Hz), 7.21 (1H, dt, J ) 1.8, 7.5 Hz), 7.29 (1H, dt, J )
2.0, 7.4 Hz), 7.57 (1H, dd, J ) 2.0, 7.4 Hz). 13C NMR (50 MHz,
CDCl3) δ 20.8, 116.3, 122.5, 126.1, 126.4, 128.6, 130.1, 130.3,
4-Eth en yl-1,3-ben zen ed iol (3). Under a nitrogen atmo-
sphere, butyllithium in hexane (0.5 mL, 0.8 mmol) was added
to a freeze-evacuated THF (2 mL) solution of 3-acetoxy-4-
vinylphenyl pivalate (52 mg, 0.2 mmol) at room temperature.
The mixture was freeze-evacuated and stirred at room tem-
perature for 1 h. Then, the reaction was quenched by adding
0.1 M phosphate buffer (pH 7.2, 10 mL). After addition of
brine, the organic materials were extracted twice with ethyl
acetate. The aqueous layer was acidified to pH 5 by addition
of sat. aq KHSO4 and extracted with ethyl acetate. The
combined extracts were washed with brine, dried over Na2SO4,
and concentrated to a small volume (ca. 0.2 mL) in vacuo. The
solvents must not be removed to dryness, otherwise polymer-
ization will take place. A trace amount of ethyl acetate was
removed by repeated addition and evaporation of methanol.
After performing reverse phase chromatography (Lobar col-
umn, ODS, H2O:MeOH ) 1:1), fractions containing 3 were
collected, and methanol was removed in vacuo. The organic
materials were extracted with ethyl acetate, washed with
brine, and dried over Na2SO4. The solution was concentrated
to a small volume, and NMR spectra were obtained by solvent
exchange to CD3OD. The yield (72%) was estimated by NMR
with an internal standard dioxane. MS spectra were recorded
as a solution. 1H NMR (400 MHz, CD3OD) δ 4.97 (1H, dd, J
) 1.7, 11.2 Hz), 5.53 (1H, dd, J ) 1.9, 17.8 Hz), 6.26 (1H, dd,
J ) 2.4, 9.0 Hz), 6.26 (1H, d, J ) 2.0 Hz), 6.88 (1H, dd, J )
11.2, 17.9 Hz), 7.22 (1H, d, J ) 9.0 Hz). 13C NMR (100 MHz,
CD3OD) δ 103.4, 108.0, 110.5, 118.3, 128.2, 132.9, 157.0, 159.1.
MS (EI, 70 eV) m/z 136 (M+, 100), 121 (M+ - Me, 11). HRMS
(EI, 70 eV) calcd for C8H8O2: 136.0525. Found: 136.0529.
Pyridine (1 mL) was added to the CD3OD solution, and CD3OD
was evaporated. Then, acetic anhydride (1 mL) was added,
and the mixture was stirred for 5 h at room temperature.
Saturated aq KHSO4 was added, and the organic materials
were extracted with ether. After being dried over Na2SO4, the
solvents were removed, and silica gel chromatography gave
4-ethenyl-1,3-benzenediol diacetate (18 mg, 48%). The NMR
spectra coincided with the authentic sample.
147.9, 169.2. IR (neat) 1765, 1632, 915, 714 cm-1
C10H10O2: calcd 162.0681. Found: 162.0669.
. HRMS
2-Eth en yl-6-ter t-bu tylp h en yl Aceta te (5). 1H NMR (400
MHz, CDCl3) δ 1.35 (9H, s), 2.35 (3H, s), 5.30 (1H, dd, J )
1.6, 11.2 Hz), 5.70 (1H, dd, J ) 1.6, 17.6 Hz), 6.60 (1H, dd, J
) 11.2, 17.6 Hz), 7.16 (1H, t, J ) 8.0 Hz), 7.33 (1H, dd, J )
1.6, 8.0 Hz), 7.42 (1H, dd, J ) 1.6, 8.0 Hz). 13C NMR (100
MHz, CDCl3) δ 21.5, 30.6, 34.7, 116.5, 124.7, 125.8, 126.7,
131.3, 131.8, 141.5, 146.7, 169.0. IR (neat) 1767 cm-1
.
MS
m/z 218 (M+, 8), 176 (M+ - CH2CO, 63), 161 (M+ - C4H9, 100).
HRMS calcd for C14H18O2: 218.1306. Found: 218.1298.
A
deuteration experiment was conducted using 2-tert-butylphe-
nol except that the reaction was worked up with 2 M NaOD
in D2O. Deuterated 5 was obtained in 78% yield. By 1H NMR
the product contained 30% of 5, 15% of (Z)-5-d, and 15% of
(E)-5-d. 1H NMR (CDCl3) δ 5.29 (1H, d, J ) 11.2 Hz). (E)-5-
d. 1H NMR (CDCl3) δ 5.69 (1H, d, J ) 17.6 Hz). No
deuteration was observed at the aromatic proton. Treatment
of 5 with 2 M NaOD in D2O at 90 °C for 1 h resulted in no
deuteration at the aromatic and vinyl protons.
2-Eth en yl-1,3-ben zen ediol (4). Mp 73.8-74.5 °C (AcOEt-
MeOH). 1H NMR (400 MHz, CD3OD) δ 5.27 (1H, dd, J ) 2.9,
12.2 Hz), 6.07 (1H, dd, J ) 3.0, 17.9 Hz), 6.29 (2H, d, J ) 8.1
Hz), 6.81 (1H, t, J ) 8.1 Hz), 6.92 (1H, dd, J ) 12.0, 17.9 Hz).
13C NMR (100 MHz, CD3OD) δ 107.8, 113.5, 117.2, 128.8,
129.4, 157.9. IR (KBr) 3468, 3404, 1635, 1626, 792, 785, 754
cm-1. MS (EI, 70 eV) m/z 136 (M+, 100), 118 (M+ - Me, 6),
107 (M+ - CHO, 12). HRMS (EI, 70 eV) calcd for C8H8O2:
136.0524. Found: 136.0526.
3-Eth en yl-2-h yd r oxyben zoic Acid . A mixture of 2-(tri-
fluoromethyl)-6-ethenylphenyl acetate (117 mg, 0.51 mmol),
ether (10 mL), and 2 M KOH (20 mL) was heated at reflux for
30 min. The cooled solution was then acidified with 2 M HCl
and extracted with ether. The organic layer was dried over
Na2SO4, filtered, and concentrated in vacuo. Flash chroma-
tography on silica gel with ethyl acetate-hexane (1:1) gave
the product (68 mg, 80%). Mp 124.2-125.5 °C (EtOH-Et2O)
(lit.25 131-133 °C). 1H NMR (400 MHz, CDCl3) δ 5.36 (1H,
dd, J ) 10.4, 1.6 Hz), 5.82 (1H, dd, J ) 17.6, 1.6 Hz), 6.92
(1H, t, J ) 8.4 Hz), 7.07 (1H, dd, J ) 17.6, 11.2 Hz), 7.71 (1H,
dd, J ) 7.6, 1.6 Hz), 7.87 (1H, dd, J ) 8.0, 1.6 Hz), 10.87 (2H,
brs). 13C NMR (100 MHz, CDCl3) δ 111.2, 115.5, 119.1, 126.7,
130.1, 130.2, 133.4, 159.4, 174.0. IR (CHCl3) 3250-2700, 1659
cm-1. MS (EI, 70 eV) m/z 164 (M+, 58), 146 (M+ - H2O, 52),
118 (M+ - H2CO2, 100). HRMS (EI, 70 eV) calcd for C9H8O3:
164.0473. Found: 164.0473.
3-Eth en yl-1,2-ben zen ed iol (2). Under a nitrogen atmo-
sphere, a solution of 2-(tert-butyldimethylsilyloxy)-6-vinyl-
phenyl acetate (154 mg, 0.5 mmol) in methanol (5 mL) and
water (1 mL) was freeze-evacuated. After addition of K2CO3
(69 mg, 0.5 mmol) and KF (29 mg, 0.5 mmol), the mixture was
freeze-evacuated again and stirred for 6 h at room tempera-
ture. Then, 0.1 M phosphate buffer (pH 7.2, 10 mL) and brine
were added, and the organic materials were extracted twice
with ethyl acetate. The combined extracts were dried over
Na2SO4, concentrated, and flash chromatographed over silica
gel, giving 2 (50 mg, 74%). Mp 26.6-27.8 °C (benzene-
hexane). 1H NMR (400 MHz, CD3OD) δ 5.15 (1H, dd, J ) 1.7,
11.3 Hz), 5.69 (1H, dd, J ) 1.7, 17.8 Hz), 6.61 (1H, t, J ) 7.8
Hz), 6.67 (1H, dd, J ) 1.7, 7.5 Hz), 6.91 (1H, dd, J ) 1.7, 7.5
Hz), 7.00 (1H, dd, J ) 11.2, 17.8 Hz). 13C NMR (100 MHz,
CD3OD) δ 113.6, 115.1, 118.1, 120.3, 126.3, 133.1, 144.3, 146.4.
IR (KBr) 3350, 1618 790, 736 cm-1. MS (EI, 70 eV) m/z 135
(M+, 100), 110 (M+ - C2H2, 78). HRMS (EI, 70 eV) calcd for
C8H8O2: 136.0525. Found: 136.0529. 1H NMR spectral data
in acetone-d6 agreed with the reported values.14
2-Eth en yl-1,4-ben zen ed iol (1). The same procedures
were employed except that KF was not added. Mp 107.8-
108.4 °C (AcOEt-MeOH) (lit.13 mp 111 °C). 1H NMR (400
MHz, CDCl3) δ 4.47 (1H, brs), 4.66 (1H, brs), 5.35 (1H, dd, J
) 11.0, 1.2 Hz), 5.71 (1H, dd, J ) 17.8, 1.2 Hz), 6.64, (1H, dd,
J ) 8.5, 3.0 Hz), 6.69 (1H, d, J ) 8.3 Hz), 6.88 (1H, d, J ) 3.0
Hz), 6.89 (1H, dd, J ) 18.1, 11.7 Hz). 1H NMR (400 MHz,
CD3OD) δ 5.13 (1H, dd, J ) 1.6, 11.0 Hz), 5.64 (1H, dd, J )
1.6, 17.9 Hz), 6.54 (1H, dd, J ) 3.0, 8.6 Hz), 6.61 (1H, d, J )
8.4 Hz), 6.86 (1H, d, J ) 3.0 Hz), 6.95 (1H, dd, J ) 11.0, 17.9
Hz). 13C NMR (100 MHz, CDCl3) δ 113.3, 115.7, 116.0, 116.9,
125.7, 131.1, 146.9, 149.4. 13C NMR (100 MHz, CD3OD) δ
113.0, 113.3, 116.7, 117.5, 126.6, 133.1, 149.0, 151.2. IR (KBr)
2,6-Dieth en yl-4-m eth oxyp h en yl Aceta te. Ethyne was
bubbled into chlorobenzene (170 mL) at -50 °C for 1 h.
Bubbling was stopped, and SnCl4 (5.9 mL, 50 mmol) and Bu3N
(11.9 mL, 50 mmol) were added. The mixture was stirred at
room temperature for 1 h under an argon atmosphere, and
then p-methoxyphenol (7, 1.24 g, 10 mmol) in chlorobenzene
(30 mL), SnCl4 (2.3 mL, 20 mmol), and Bu3N (4.8 mL, 20 mmol)
3250, 1626, 1612, 916 cm-1
.
(25) Iwasaki, M.; Tirrell, D.; Vogl, O. J . Polym. Sci., Polym. Chem.
1980, 18, 2755.
(24) Dhekne, V. V.; Rao, A. S. Synthesis 1980, 58.

Ortho-Vinylation Reaction of Phenols with Ethyne
J . Org. Chem., Vol. 63, No. 21, 1998 7305
were added successively. After the mixture was heated at 100
°C for 1 h, 2 M NaOH (400 mL) and ethanol (150 mL) were
added, and heating was continued for another 2 h at 100 °C.
The mixture was cooled and acidified with 2 M HCl. The
organic materials were extracted with ether, washed with
brine, dried over MgSO4, and filtered. After removal of ether
under reduced pressure, pyridine (8.1 mL) and acetic anhy-
dride (4.7 mL) were added to the resulting chlorobenzene
solution, and the products were acetylated by stirring at room
temperature for 12 h. The mixture was poured into water,
and the organic materials were extracted with ether, washed
with brine, dried over MgSO4, filtered, and concentrated.
Flash chromatography (hexane:ethyl acetate ) 100:1) over
silica gel gave 2,6-diethenyl-4-methoxyphenyl acetate (1.49 g,
77%). It contained about 5% of 2-ethenyl-4-methoxyphenyl
4-Meth oxy-2-(1-p h en yleth en yl)p h en ol. Under an argon
atmosphere, a mixture of p-methoxyphenol (7, 124 mg, 1
mmol), phenylacetylene (100 mg, 1.0 mmol), SnCl4 (0.48 mL,
4 mmol), and Bu3N (1.0 mL, 4 mmol) in chlorobenzene (20 mL)
was heated at 60 °C for 30 min. 2 M KOH (40 mL) and ethanol
(10 mL) were added, and refluxing was continued for another
1 h. After being cooled to room temperature, the contents were
poured into a mixture of ether and 2 M HCl, and the organic
materials were extracted with ether. The organic layer was
dried over Na2SO4 and concentrated. 4-Methoxy-2-(1-phenyl-
ethenyl)phenol (130 mg, 57%) and 4-methoxy-2,6-bis(1-phenyl-
ethenyl)phenol (63 mg, 19%) were obtained along with the
recovered 7 (14 mg, 11%) by flash chromatography over silica
gel. 1H NMR (400 MHz, CDCl3) δ 3.75 (3H, s), 4.77 (1H, s),
5.42 (1H, d, J ) 1.6 Hz), 5.86 (1H, d, J ) 1.6 Hz), 6.69 (1H, d,
J ) 2.8 Hz), 6.83 (1H, dd, J ) 8.4, 2.8 Hz), 6.88 (1H, d, J )
8.8 Hz), 7.36 (5H, m). 13C NMR (100 MHz, CDCl3) δ 55.8,
115.0, 115.2, 116.4, 116.6, 126.8, 128.0, 128.4, 128.6, 139.0,
145.1, 146.9, 153.1. IR (neat) 3526, 1488 cm-1. MS (EI) m/z
226 (M+, 67), 225 (M+ - H, 100), 211 (M+ - Me, 29). HRMS
calcd for C15H14O2: 226.0994. Found: 226.1000.
1
acetate as indicated by H NMR. 1H NMR (200 MHz, CDCl3)
δ 2.33 (3H, s), 3.83 (3H, s), 5.34 (2H, dd, J ) 11.0, 1.0 Hz),
5.73 (2H, dd, J ) 17.5, 1.1 Hz), 6.66 (2H, dd, J ) 17.5, 11.0
Hz), 7.00 (2H, s). 13C NMR (50 MHz, CDCl3) δ 20.4, 55.4,
110.7, 116.7, 130.3, 131.5, 139.3, 157.1, 169.1. IR (neat) 1767,
1597, 1031, 920, 756 cm-1
.
MS (EI) m/z 218 (M+, 12), 176
(100). HRMS calcd for C13H14O3: 218.0943. Found: 218.0966.
2,6-Dieth en yl-4-ter t-bu tylp h en ol. A 5:1 mixture of 2,6-
diethenyl-4-tert-butylphenyl acetate and 2-ethenyl-4-tert-bu-
tylphenyl acetate (171 mg, 0.71 mmol) was obtained from
4-tert-butylphenol (150 mg, 1.0 mmol). Under an argon
atmosphere, K2CO3 (98 mg, 0.71 mmol) was added to a
methanol (10 mL) solution of the above mixture. After stirring
for 1 h, water was added, and the organic materials were
extracted twice with ether. The combined extracts were
washed with brine, dried over MgSO4, and concentrated in
vacuo. 2,6-Diethenyl-4-tert-butylphenol (118 mg, 58% yield
from 4-tert-butylphenol) was obtained as a colorless oil by flash
chromatography (hexane:ethyl acetate ) 30:1) over silica gel.
1H NMR (200 MHz, CDCl3) δ 1.33 (9H, s), 5.31 (1H, s), 5.42
(2H, dd, J ) 11.2, 1.4 Hz), 5.73 (2H, dd, J ) 17.7, 1.4 Hz),
6.94 (2H, dd, J ) 17.7, 11.3 Hz), 7.30 (2H, s). 13C NMR (50
MHz, CDCl3) δ 31.4, 34.1, 116.3, 123.8, 124.5, 132.3, 143.0,
148.0. IR (neat) 3544, 1630, 996, 911, 882 cm-1. MS (EI) m/z
202 (M+, 33), 187 (M+ - Me, 100). HRMS calcd for C14H18O:
202.1356. Found: 202.1355.
4,7-Dim et h yl-7-et h en yl-2,5-b icyclo[2.2.2]oct a d ien -8-
on e (15). 2,6-Dimethylphenol (122 mg, 1.0 mmol) was vinyl-
ated with ethyne by standard procedures, and the reaction was
worked up by adding 2 M NaOH and heating at 90 °C for 1 h.
After being cooled to room temperature, the organic layer was
separated, washed twice with 2 M HCl, and dried over Na2SO4.
Chlorobenzene was removed in vacuo, and NMR analysis of
the crude product indicated the formation of 15 in 60% yield.
Very rapid flash chromatography on silica gel gave pure 15
(52 mg, 30%). 1H NMR (400 MHz, CDCl3) δ 1.19 (3H, s), 1.56
(3H, s), 3.67 (1H, m), 4.99 (1H, d, J ) 11.6 Hz), 5.09 (1H, d, J
) 17.6 Hz), 5.71 (1H, dd, J ) 16.8, 10.0 Hz), 6.02 (1H, d, J )
6.4 Hz), 6.09 (1H, d, J ) 6.4 Hz), 6.50 (1H, t, J ) 6.4 Hz), 6.56
(1H, t, J ) 6.4 Hz). 13C NMR (100 MHz, CDCl3) δ 15.7, 27.1,
47.4, 48.2, 58.2, 114.0, 133.5, 135.1, 135.8, 136.4, 143.0, 206.6.
IR (neat) 2972, 2931, 1716, 1454, 995, 917 cm-1. Deuteration
experiments were conducted using 2 M NaOD in D2O giving
15-d3 in 30% isolated yield. 1H NMR absorptions at δ 6.56,
6.02, and 4.99 disappeared, indicating >95% deuteration.
Ack n ow led gm en t. The authors thank Dr. Akio
Hayashi for the work at the initial stage of the present
reaction. We also thank Mr. Go Hirai and Mr. Katsumi
Kobayashi for their assistance. This work was supported
by grants from the J apan Society of Promotion of
Science (RFTF 97P00302) and the Ministry of Educa-
tion, Science and Culture, J apan (No. 08404050).
2,6-Dieth en yl-1,4-ben zen ed iol. Under an argon atmo-
sphere, KF (77 mg, 1.32 mmol) was added to a freeze-
evacuated methanol solution (10 mL) of 2,6-diethenyl-4-(tert-
butyldimethylsilyloxy)phenol (182 mg, 0.66 mmol). The mixture
was stirred for 1 h, and then water was added. The organic
materials were extracted twice with ether, washed with brine,
dried over MgSO4, and concentrated in vacuo. 2,6-Diethenyl-
1,4-benzenediol (71 mg, 66%) was obtained by flash chroma-
tography over silica gel (hexane:ethyl acetate ) 2.5:1). Mp
131-132 °C (toluene). 1H NMR (200 MHz, CDCl3) δ 5.19 (2H,
dd, J ) 11.1, 0.8 Hz), 5.62 (2H, dd, J ) 17.7, 0.8 Hz), 6.83
(2H, s), 7.02 (2H, dd, J ) 17.7, 11.1 Hz). 13C NMR (50 MHz,
CDCl3) δ 112.9, 114.3, 129.3, 133.0, 145.7, 151.9. IR (KBr)
Su p p or tin g In for m a tion Ava ila ble: Spectral data of the
vinylphenol derivatives described in the present study. 1H
NMR and 13C NMR spectra of vinylphenols are also included
(86 pages). This material is contained in libraries on micro-
fiche, immediately follows this article in the microfilm version
of the journal, and can be ordered from the ACS; see any
current masthead page for ordering information.
3260, 1450, 1415, 1361, 1201, 1000, 962, 920, 862, 787 cm-1
.
MS (EI) m/z 162 (M+, 100), 147 (M+ - Me, 48). HRMS calcd
for C10H10O2: 162.0680. Found: 162.0681. Anal. Calcd for
C
10H10O2: C, 74.06%; H, 6.21%. Found: C, 74.15%; H, 6.32%.
J O980785F