Nickel- and zinc-promoted [2 + 2 + 2] cycloaddition of diynes and α, β-enones

Article abstract of DOI:10.1021/jo980987b

The [2 + 2 + 2] cycloaddition of diynes and enones occurred in the presence of both nickel and zinc together. This binary metal-mediated reaction had two interesting features: (1) a terminally unsubstituted diyne reacted with an enone to give an aromatic compound with the concomitant incorporation of two hydrogen atoms abstracted from an expected 1, 3-diene product into another molecule of the starting enone and (2) a trimethylsilyl-substituted diyne reacted with an equimolar amount of enone to regioselectively afford a 1, 3-diene, in which the trimethylsilyl group is adjacent to the carbonyl group.

Full text of DOI:10.1021/jo980987b

7
026
J . Org. Chem. 1998, 63, 7026-7029
Nick el- a n d Zin c-P r om oted [2 + 2 + 2] Cycloa d d ition of Diyn es a n d
r,â-En on es
,
†
Shin-ichi Ikeda,* Hitomi Watanabe, and Yoshiro Sato
Faculty of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori,
Mizuho-ku, Nagoya 467-8603, J apan
Received May 26, 1998
The [2 + 2 + 2] cycloaddition of diynes and enones occurred in the presence of both nickel and zinc
together. This binary metal-mediated reaction had two interesting features: (1) a terminally
unsubstituted diyne reacted with an enone to give an aromatic compound with the concomitant
incorporation of two hydrogen atoms abstracted from an expected 1,3-diene product into another
molecule of the starting enone and (2) a trimethylsilyl-substituted diyne reacted with an equimolar
amount of enone to regioselectively afford a 1,3-diene, in which the trimethylsilyl group is adjacent
to the carbonyl group.
In tr od u ction
2 + 2 + 2] cycloadditions of three unsaturated
Ch a r t 1
[
substrates lead to the formation of three new carbon-
carbon bonds in one step.1 Such reactions are generally
promoted by the use of various transition-metal com-
plexes as catalysts or stoichiometric reagents.2 In par-
ticular, the partially intramolecular cycloadditions of
diynes and alkynes result in the construction of chemo-
and regioselective annelated benzenes (Chart 1).3 Re-
cently, the regioselective cycloaddition of differently
4
substituted diynes with 1-alkynes was also reported. On
the contrary, the [2 + 2 + 2] cycloaddition of diynes and
alkenes has not yet been established as a synthetic
method, since two problems remain unsolved: i.e., (i) a
Ta ble 1.
5
high ratio of alkene to diyne is required and (ii) there is
no known example of regiochemical control for the
reaction of a diyne with an alkene.6
,7
We recently reported the cotrimerization of R,â-enones
and alkynes in the presence of a nickel and aluminum
7
catalytic system. However, this binary catalytic system
could not be applied to the reaction of diynes with enones.
We have since researched other combinations of metals
and have found an efficient system for this reaction.
a
ZnCl2, Et3N,
1a ,
time, yield, %
Resu lts a n d Discu ssion
run
catalyst
Ni(cod)2
NiCl2/Zn
NiCl2/Zn
NiCl2/Zn
NiCl2/Zn
equiv equiv equiv
h
3/4
When the reaction of 3-buten-2-one (1a ) with a termi-
nally unsubstituted diyne 2a (1 mmol) was carried out
in the presence of Ni(cod) (10 mol %) in MeCN at reflux
2
for 2 h, the starting material 2a disappeared and a small
amount of cycloadduct was obtained in 13% yield along
with a trace amount of dimer 4 (run 1 in Table 1).8 The
1
2
3
4
5
6
7
8
0
0
2.1
2.1
2.1
2.1
2.1
2.1
2.1
1.1
2
2
2
2
2
2
2
8
(13)/trace
21/0
34/0
44/0
77/0
31/0
29/0
37/0
0
0
0.6
1.4
1.4
1.4
1.4
1.4
0
0
1.5
1.5
1.5
1.5
Ni(cod)2
,9
NiCl2/Zn/CODb
NiCl2/Zn
†
Fax: +81-52-836-3462. E-mail: ikeshin@phar.nagoya-cu.ac.jp.
1) Dower, W. V.; Vollhardt, K. P. C. J . Am. Chem. Soc. 1982, 104,
878.
2) (a) Schore, N. E. Chem. Rev. 1988, 88, 1081. (b) Lautens, M.;
Klute, W.; Tam, W. Chem. Rev. 1996, 96, 49.
a
Isolated yield. GC yield is in parentheses. b 1,5-Cyclooctadiene
(
(COD, 20 mol %) was added under the reaction conditions in run
6
5
.
(
(
(
3) Vollhardt, K. P. C. Angew. Chem., Int. Ed. Engl. 1984, 23, 539.
4) McDonald, F. E.; Zhu, H. Y. H.; Holmquist, C. R. J . Am. Chem.
cycloadduct was assigned to be an aromatic compound
, rather than the expected 1,3-cyclohexadiene 5, based
3
Soc. 1995, 117, 6605.
5) Recent reports: Grigg, R.; Scott, R.; Stevenson, P. J . Chem. Soc.,
1
(
on the H NMR spectra. The use of NiCl
and Zn dust (100 mol %) instead of Ni(cod)
2
(10 mol %)
afforded the
Perkin Tarns. 1 1988, 1365. Zhou, Z.; Battaglia, L. P.; Chiusoli, G. P.;
Costa, M.; Nardelli, M.; Pelizzi, C.; Predieri, G. J . Chem. Soc., Chem.
Commun. 1990, 1632. Zhou, Z.; Costa, M.; Chiusoli, G. P. J . Chem.
Soc., Perkin Trans. 1 1992, 1399.
2
desired 3 in 21% isolated yield (run 2).9 In this reaction,
NiCl
along with ZnCl
promoted the desired cycloaddition of 1a and 2a (runs 3
and 4).9 When Et
N was added to the reaction medium,
2
would react with Zn to prepare a Ni(0) species
(
6) For the regioselective cycloaddition of completely intermolecular
alkenes and alkynes, see: Chalk, A. J . J . Am. Chem. Soc. 1972, 94,
928. Balaich, G. J .; Rothwell, I. P. J . Am. Chem. Soc. 1993, 115, 1581.
7) Ikeda, S.; Mori, N.; Sato, Y. J . Am. Chem. Soc. 1997, 119, 4779.
2
. The additional ZnCl more effectively
2
5
(
3
S0022-3263(98)00987-6 CCC: $15.00 © 1998 American Chemical Society
Published on Web 09/09/1998

Ni- and Zn-Promoted Cycloaddition of Diyenes and R,â-Enones
J . Org. Chem., Vol. 63, No. 20, 1998 7027
cycloaddition proceeded to afford 3 in 77% yield (run 5).
The presence of 1,5-cyclooctadiene (COD) impaired the
cycloaddition (runs 6 and 7). When 2a was reacted with
an equimolar amount of 1a under the reaction conditions
in run 5, 3 was obtained in only 37% yield (run 8).
The nickel and zinc system did not promote the
cycloaddition of 2a with 3-butyn-2-one. Moreover, in the
crossover experiment depicted in eq 2, cycloadduct 6,
arising from the reaction of 1-hexyne with 2a , was not
obtained. These results indicate that 2 specifically
This binary metal system could be applied to the
reaction of terminally mono- or disubstituted diynes.
Ethyl-substituted diyne 2d reacted with 1a to give a
mixture of 1,3-dienes 11a and 11b along with the
corresponding aromatized compounds 12a and 12b (eq
reacted with 1 in the presence of this binary metal
system.10
7
). However, the reaction of trimethylsilyl-substituted
diyne 2e smoothly proceeded with an equimolar amount
of 1a to afford 1,3-cyclohexadiene 13 regioselectively (eq
8
). Neither the regioisomer nor their aromatized prod-
ucts were formed in the reaction. The structure of 13
was determined by the 1H NMR spectra of the corre-
sponding aromatized compound derived from treatment
with DBU in air.7
Diynes 2b and 2c also reacted with 1a to give the
corresponding aromatized cycloadducts 7 and 8, respec-
tively (eqs 3 and 4). The expected cyclohexadienes were
not obtained in these reactions.
The stoichiometry of these reactions indicates that two
hydrogen atoms in the reactants are formally abstracted
from the expected product, i.e., 1,3-cyclohexadiene. Al-
though the aromatization of the obtained products in situ
is generally known to be a secondary reaction in the
cycloaddition of alkynes with alkenes,11 the details have
not been fully investigated. We found that these were
incorporated into another molecule of the starting mate-
rial 1. Thus, the reaction of 2a with 1b gave an
equimolar amount of cyclohexanone with 9 (eq 5).
The results of the regioselective cycloaddition of 1a
with trimethylsilyl-substituted diynes are shown in Table
2
. Diynes 2f and 2g also gave 14 and 15, respectively.
Diyne 2h reacted with 1a to give 16, in which the
trimethylsilyl group is adjacent to the acetyl group.
Cyclohexadiene 17 containing a fused cyclohexane ring
(
8) The formation of 4 was identified by the GC/MS spectra (m/z )
+
4
72 (M )).
9) Unidentified polymeric compounds would also be formed, causing
incomplete material balances.
10) For a nickel-catalyzed [2 + 2 + 2] cyclization of diynes and
acetylene, see: Sato, Y.; Nishimata, T.; Mori, M. J . Org. Chem. 1994,
(
(
5
9, 6133 and references therein.
11) Carbonaro, A.; Greco, A.; Dall’Asta, G. Tetrahedron Lett. 1968,
129. Singleton, D. M. Tetrahedron Lett. 1973, 1245. Macomber, D.
The reaction with 1c (1.1 equiv vs 2a ), which could not
be led to an aromatic cycloadduct, proceeded smoothly
to give 10 in 65% yield (eq 6).
(
5
W.; Verma, A. G. Organometallics 1988, 7, 1241.

7
028 J . Org. Chem., Vol. 63, No. 20, 1998
Ikeda et al.
Ta ble 2. Cycloa d d ition of 1a w ith
Tr im eth ylsilyl-Su bstitu ted Diyn es
Sch em e 1
a
a
Reaction conditions: NiCl2 (0.1 mmol), Zn dust (1.0 mmol),
ZnCl2 (1.4 mmol), Et3N (1.5 mmol), 1a (1.0 mmol), and diyne (1.0
b
mmol) in MeCn (4 mL) at reflux for 2 h. Diastereoselectivity was
determined by integration of the methyne protons in 1H NMR.
poration of two hydrogen atoms into another molecule
of the starting enone. On the other hand, the reaction
of a trimethylsilyl-substituted diyne with an equimolar
amount of enone regiospecifically gave a cyclohexadiene
in which the trimethylsilyl group is adjacent to the
carbonyl group. To the best of our knowledge, this is the
first example of the completely regiochemically controlled
cycloaddition of diynes and alkenes.
was formed from 2i. The obtained regiochemically
defined cycloadducts are attractive compounds because
2
the trimethylsilyl group attached to an sp -carbon atom
can be easily converted into various functional groups.12
A plausible mechanism for the present reaction is
shown in Scheme 1. Metallacycle 1813 or 19, followed
by intermediate 20, is generated from Ni(0) species, 1,
and 2. Reductive elimination of 20 gives 1,3-diene 21.
The regiochemically defined trimethylsilyl-substituted 21
14
Exp er im en ta l Section
Gen er a l. All reactions were carried out under a dry N
2
3
(R ) Me
3
Si) is derived from the preferential coupling
atmosphere. 1H and C NMR Spectra were recorded in CDCl
13
between the unsubstituted or methyl-substituted carbon-
carbon triple bond in 2 (R′ ) H or Me) and the carbon
4
using Me Si as internal standard. Acetonitrile (MeCN) was
distilled from P O . Zn dust was commercially available from
2 5
Nacalai Tesque, Inc. and was used without activation proce-
dure.
Typ ica l P r oced u r e. In a 20-mL three-necked flask were
atom â-position in 1, since the Me
3
Si group acts as a
deactivating substituent.15 When both the R and R′
groups in 2a -c are hydrogen atoms (R, R′ ) H), the
obtained 1,3-diene 21 would be easily dehydrogenated to
give aromatized product 22 in the presence of Ni(0)
placed NiCl
dust (66 mg, 1.0 mmol), MeCN (4 mL), and Et
mmol), and the solution was stirred at room temperature for
min. To this suspension were added 2a (236 mg, 1.0 mmol)
2
(13 mg, 0.1 mmol), ZnCl
2
(190 mg, 1.4 mmol), Zn
3
N (152 mg, 1.5
species and Et
3
2
N. The resulting nickel hydride (Ni-H )
5
reacts with another molecule of 1 to regenerate Ni(0)
and 1a (148 mg, 2.1 mmol) at room temperature, and the
mixture was then stirred at reflux for 2 h. After addition of
species and also produces a saturated ketone.16
aqueous HCl, the aqueous layer was extracted with Et
combined organic layers were washed successively with aque-
ous NaHCO and brine, dried over MgSO , and concentrated
in vacuo. Purification by silica gel column chromatography
2
O. The
Con clu sion
The nickel- and zinc-mediated [2 + 2 + 2] cycloaddition
of diynes and enones had two interesting features. First,
a terminally unsubstituted diyne reacted with enones (2
equiv vs diyne) to give an aromatized compound, rather
than a 1,3-cyclohexadiene, with the concomitant incor-
3
4
(
hexane:AcOEt ) 4:1) gave 235 mg (77%) of 3.
Dieth yl 5-a cetylin d a n -2,2-d ica r boxyla te (3): a colorless
oil; bp 165 °C (1.2 mmHg); R
f
) 0.23 (hexane:AcOEt ) 4:1);
1
H NMR (400 MHz, CDCl
3
) δ 1.24 (t, J ) 7.1 Hz, 6 H), 2.56 (s,
3
H), 3.61 (s, 4 H), 4.20 (q, J ) 7.1 Hz, 4 H), 7.26 (d, J ) 8.4
-
1
(
12) Colvin, E. W. Silicon in Organic Synthesis; Butterworth:
London, 1981; Chapter 7.
13) For the nickelacyclopentadienes: Eisch, J . J .; Damasevitz, G.
Hz, 1 H), 7.76-7.78 (m, 2 H); IR (neat) 1734, 1684 cm ; GC/
+
MS (EI, 70 eV) m/z (rel int) 304 (M , 82), 230 (100). Anal.
(
Calcd for C17
.98.
-Acetylisoben zofu r a n (7): a colorless oil; bp 150 °C (25
20 5
H O : C, 67.09; H, 6.62. Found: C, 66.84; H,
A. J . Organomet. Chem. 1975, 96, C19. Eisch, J . J .; Galle, J . E. J .
Organomet. Chem. 1975, 96, C23. Hoberg, H.; Richter, W. J . Orga-
nomet. Chem. 1980, 195, 355. Eisch, J . J .; Aradi, A. A.; Han, K. I.
Tetrahedron Lett. 1983, 24, 2073.
6
5
1
mmHg); R
CDCl ) δ 2.61 (s, 3 H), 5.14 (s, 4 H), 7.31 (d, J ) 7.6 Hz, 1 H),
.83-7.90 (m, 2 H); IR (neat) 1682 cm ; GC/MS (EI, 70 eV)
f
) 0.21 (hexane:AcOEt ) 3:1); H NMR (270 MHz,
(
14) (a) See ref 7. (b) Ikeda, S.; Kondo, K.; Sato, Y. J . Org. Chem.
996, 61, 8248. (c) Montgomery, J .; Oblinger, E.; Savchenko, A. V. J .
Am. Chem. Soc. 1997, 119, 4911.
15) Tsuda, T.; Morikawa, S.; Hasegawa, N.; Saegusa, T. J . Org.
Chem. 1990, 55, 2978.
16) The added ZnCl
although the detail is unclear.
3
1
-1
7
+
m/z (rel int) 162 (M , 100). Anal. Calcd for C10
10 2
H O : C,
(
7
4.06; H, 6.21. Found: C, 73.79; H, 6.27.
6-Acetyltetr a lin (8): a colorless oil; bp 130 °C (8 mmHg);
(
would act as a Lewis acid and activate 1,7
2
1
R
f
) 0.57 (hexane:AcOEt ) 3:1); H NMR (270 MHz, CDCl ) δ
3

Ni- and Zn-Promoted Cycloaddition of Diyenes and R,â-Enones
J . Org. Chem., Vol. 63, No. 20, 1998 7029
1
.78-1.83 (m, 4 H), 2.55 (s, 3 H), 2.30-2.80 (m, 4 H), 7.13 (d,
9 H), 1.19 (s, 3 H), 2.59 (s, 3 H), 2.72 (d, J ) 15.3 Hz, 1 H),
2.81 (d, J ) 15.3 Hz, 1 H), 4.69 (s, 1 H), 7.25 (d, J ) 7.6 Hz,
-
1
J ) 8.6 Hz, 1 H), 7.64-7.67 (m, 2 H); IR (neat) 1682 cm
GC/MS (EI, 70 eV) m/z (rel int) 174 (M , 30), 159 (100). Anal.
;
+
-1
1 H), 7.48 (d, J ) 7.6 Hz, 1 H); IR (disk) 1688 cm ; GC/MS
+
Calcd for C12
,7-Dieth oxyca r bon ylcyclop en ta [g]tetr a lon e (9): a col-
orless oil; bp 190 °C (1.2 mmHg); R ) 0.21 (hexane:AcOEt )
) δ 1.23 (t, J ) 7.3 Hz, 6 H),
.02-2.12 (m, 2 H), 2.59 (t, J ) 6.4 Hz, 2 H), 2.90 (t, J ) 6.0
H
14O: C, 82.72; H, 8.10. Found: C, 82.47; H, 8.25.
(EI, 70 eV) m/z (rel int) 390 (M , 0), 375 (79), 333 (100). Anal.
7
Calcd for C22
9.88.
38 2 2
H O Si : C, 67.63; H, 9.80. Found: C, 67.56; H,
f
1
3
2
:1); H NMR (270 MHz, CDCl
3
5,6-Dih yd r o-6-a cetyl-1-[(ter t-bu tyld im eth ylsilyl)oxy]-
2,2-d im eth yl-7-(tr im eth ylsilyl)in d a n (15): diastereoselec-
Hz, 2 H), 3.55 (s, 4 H), 4.18 (q, J ) 7.3 Hz, 4 H), 7.07 (s, 1 H),
7
tivity 75%; a colorless oil; bp 105 °C (1.3 mmHg); R ) 0.49
f
-
1
1
.84 (s, 1 H); IR (neat) 1734, 1682 cm ; GC/MS (EI, 70 eV)
(hexane:AcOEt ) 10:1); H NMR of major isomer (75%) (270
+
m/z (rel int) 330 (M , 29), 256 (100). Anal. Calcd for
: C, 69.07; H, 6.71. Found: C, 68.79; H, 6.75.
Dieth yl 6H-5-for m yl-5-m eth ylin d a n -2,2-d ica r boxyla te
10): a colorless oil; bp 150 °C (7 mmHg); R ) 0.31 (hexane:
) δ 1.09 (s, 3 H), 1.20-
.26 (m, 6 H), 2.14 (ddd, J ) 17.8, 6.7, 3.2 Hz, 1 H), 2.59 (ddt,
J ) 17.8, 4.6, 2.3 Hz, 1 H), 2.90-2.93 (m, 2 H), 2.95-2.99 (m,
H), 4.10-4.22 (m, 4 H), 5.29 (br s, 1 H), 5.50-5.57 (br s, 1
MHz, CDCl3) δ 0.09 (s, 3 H), 0.13 (s, 3 H), 0.19 (s, 9 H), 0.71
(s, 3 H), 0.86 (s, 9 H), 1.07 (s, 3 H), 2.18 (s, 3 H), 2.34-2.51
(m, 4 H), 3.22 (dd, J ) 8.2, 5.2 Hz, 1 H). 4.16 (s, 1 H), 5.48-
5.60 (m, 1 H); the protons of minor isomer (25%) were also
detected, δ -0.002 (s, 3 H), 0.04 (s, 3 H), 0.15 (s, 9 H), 0.85 (s,
9 H), 0.88 (s, 3 H), 1.10 (s, 3 H), 2.17 (s, 3 H), 3.13 (dd, J )
19 22 5
C H O
(
f
1
AcOEt ) 3:1); H NMR (270 MHz, CDCl
3
1
-
1
7.9, 3.1 Hz, 1 H), 4.18 (s, 1 H); IR (disk) 1707 cm ; GC/MS of
+
2
major isomer (EI, 70 eV) m/z (rel int) 392 (M , 1), 335 (100);
-
1
+
H), 9.42 (s, 1 H); IR (neat) 1732 cm ; GC/MS (EI, 70 eV) m/z
GC/MS of minor isomer (EI, 70 eV) m/z (rel int) 392 (M , 20),
+
(
C
rel int) 306 (M , 0), 276 (28), 202 (100). Anal. Calcd for
: C, 66.65; H, 7.24. Found: C, 66.43; H, 7.24.
Mixtu r e of 11 a n d 12: a pale yellow oil; bp 150 °C (5
73 (100). Anal. Calcd for C H O Si : C, 67.28; H, 10.27.
2
2
40
2
2
17
H
22
O
5
Found: C, 67.14; H, 10.29.
6-Acetyl-1-[(ter t-bu tyld im eth ylsilyl)oxy]-2,2-d im eth yl-
7-(tr im eth ylsilyl)in d a n . This compound (one isomer) was
derived from the treatment of 15 with DBU in air; a colorless
f
1
mmHg); R
1b (270 MHz, CDCl
m, 2 H), 2.16 (s, 3 H), 2.57-2.63 (m, 2 H), 3.09 (t, J ) 6.4 Hz,
H), 4.35-4.42 (m, 2 H), 4.45-4.49 (m, 2 H), 5.35-5.41 (m, 1
f
) 0.34 (hexane:AcOEt ) 3:1); H NMR of 11a and
1
(
1
3
) δ 1.01 (t, J ) 7.6 Hz, 3 H), 1.92-2.18
oil; bp 105 °C (1.5 mmHg); R ) 0.49 (hexane:AcOEt ) 10:1);
1
H NMR (500 MHz, CDCl ) δ -0.42 (s, 3 H), -0.24 (s, 3 H),
3
+
H); GC/MS of 11 (EI, 70 eV) m/z (rel int) 192 (M , 4), 119 (100);
HRMS of 11 for C12
0.36 (s, 9 H), 0.83 (s, 3 H), 0.82 (s, 9 H), 0.87 (s, 3 H), 1.24 (s,
+
H
14
O
2
(M ) calcd 190.0999, found 190.0993.
3 H), 2.40 (d, J ) 16.5 Hz, 1 H), 2.59 (s, 3 H), 3.03 (d, J ) 16.5
Mixtu r e of 5-Acetly-4-eth ylisoben zofu r a n (12a ) a n d
-Acetyl-6-eth ylisoben zofu r a n (12b). These compounds
Hz, 1 H), 4.94 (s, 1 H), 7.25 (d, J ) 7.6 Hz, 1 H), 7.61 (d, J )
4
7.6 Hz, 1 H); IR (disk) 1688 cm-1; GC/MS (EI, 70 eV) m/z (rel
were derived from the treatment of 11 with DBU in air; 12a /
1
int) 390 (M
+
, 0), 333 (M
2
+
-
t
Bu, 67), 243 (100). Anal. Calcd
2b ) 6/1; a colorless crystal; bp 140 °C (4 mmHg); mp 34-36
for C H O Si : C, 67.63; H, 9.80. Found: C, 67.34; H, 9.75.
2
2
38
2
1
°
C (hexane); R
f
) 0.34 (hexane:AcOEt ) 3:1); H NMR (270
5
,6-Dih yd r o-6-a cetyl-1-[(ter t-bu tyld im eth ylsilyl)oxy]-
,2-d im eth yl-4-m eth yl-7-(tr im eth ylsilyl)in d a n (16): dias-
tereoselectivity 67%; a colorless oil; bp 124 °C (1.0 mmHg); R
MHz, CDCl
3
) δ 1.18 (t, J ) 7.6 Hz, 3 H), 2.59 (s, 3 H), 2.75 (q,
2
J ) 7.6 Hz, 2 H), 5.15 (s, 4 H), 7.13 (d, J ) 7.7 Hz, 0.86 H),
f
7
0
1
.61 (d, J ) 7.7 Hz, 0.86 H), 7.66 (br s, 0.14 H), 7.71 (br s,
1
)
0.40 (hexane:AcOEt ) 10:1); H NMR of major isomer (67%)
-
1
.14 H); IR (disk) 1684 cm ; GC/MS (EI, 70 eV) m/z (rel int)
(
400 MHz, CDCl
3
) δ 0.07 (s, 3 H), 0.12 (s, 3 H), 0.17 (s, 9 H),
+
90 (M , 70), 175 (100). Anal. Calcd for C12
14 2
H O : C, 75.76;
0
3
.69 (s, 3 H), 0.86 (s, 9 H), 1.08 (s, 3 H), 1.70 (s, 3 H), 2.16 (s,
H, 7.42. Found: C, 75.53; H, 7.54.
,6-Dih yd r o-5-a cet yl-4-(t r im et h ylsilyl)isob en zofu r a n
13): a colorless oil; bp 130 °C (4 mmHg); R ) 0.38 (hexane:
) δ 0.12 (s, 9 H), 2.14
s, 3 H), 2.51-2.60 (m, 2 H), 3.18 (d, J ) 7.9 Hz, 1 H), 4.36-
H), 2.21?2.56 (m, 4 H), 3.25 (t, J ) 7.1 Hz, 1 H), 4.16 (s, 1
5
1
H); H NMR of minor isomer (33%) (400 MHz, CDCl
3
) δ ?0.057
(
f
(
s, 3 H), 0.01 (s, 3 H), 0.15 (s, 9 H), 0.85 (s, 3 H), 0.84 (s, 9 H),
1
AcOEt ) 3:1); H NMR (270 MHz, CDCl
3
1
3
.11 (s, 3 H), 1.69 (s, 3 H), 2.09 (s, 3 H), 2.21-2.56 (m, 4 H),
(
4
-1
.12 (br s, 1 H), 4.18 (s, 1 H); IR (neat) 1707 cm ; GC/MS of
.40 (m, 2 H), 4.52 (s, 2 H), 5.55-5.58 (m, 1 H); IR (neat) 1703
+
major product (EI, 70 ev) m/z (rel int) 406 (M , 1), 73 (100);
GC/MS of minor product (EI, 70 ev) m/z (rel int) 406 (M , 4),
7
4
-
1
+
cm ; DIMS (EI, 70 eV) m/z (rel int) 236 (M , 12), 73 (100).
Anal. Calcd for C13 Si: C, 66.05; H, 8.53. Found: C,
6.18; H, 8.74.
-Acet ly-4-(t r im et h ylsilyl)isob en zofu r a n : This com-
pound (one isomer) was derived from the treatment of 13 with
DBU in air; a colorless oil; bp 130 °C (3.5 mmHg); R ) 0.31
) δ 0.29 (s, 9
H), 2.62 (s, 3 H), 5.08 (s, 2 H), 5.17 (s, 2 H), 7.28 (d, J ) 7.9
+
H
20
O
2
+
3 (100); HRMS for C23
H
42
O
2
Si
2
(M , major isomer) calcd
6
+
06.2723, found 406.2724; HRMS for C23
42 2 2
H O Si (M , minor
5
isomer) calcd 406.2723, found 406.2731.
,7-Dih yd r o-6-a cet yl-2-[(ter t-b u t yld im et h ysilyl)oxy]-
,3-d im eth yl-5-(tr im eth ylsilyl)tetr a lin (17): diastereose-
lectivity 82%; a colorless crystal; mp 80-81 °C (hexane); R
6
f
3
1
(hexane:AcOEt ) 4:1); H NMR (270 MHz, CDCl
3
f
)
1
0
(
.60 (hexane:AcOEt ) 11:1); H NMR of major isomer (82%)
-
1
Hz, 1 H), 7.63 (d, J ) 7.9 Hz, 1 H); IR (neat) 1686 cm ; GC/
400 MHz, CDCl ) δ 0.038 (s, 6 H), 0.20 (s, 9 H), 0.83 (s, 3 H),
3
+
+
MS (EI, 70 eV) m/z (rel int) 234 (M , 0), 219 (M - Me, 100).
0
3
.88 (s, 9 H), 0.97 (s, 3 H), 2.00 (d, J ) 15.3 Hz, 1 H), 2.07 (s,
H), 2.11?2.25 (m, 2 H), 2.36 (dd, J ) 16.2, 6.0 Hz, 1 H), 2.46
Anal. Calcd for C13 Si: C, 66.62; H, 7.74. Found: C,
18 2
H O
6
6.87; H, 7.77.
,6-Dih yd r o-5-a cetyl-1-[(ter t-bu tyld im eth ylsilyl)oxy]-
,2-d im eth yl-4-(tr im eth ylsilyl)in d a n (14): diastereoselec-
(
2
d, J ) 15.3 Hz, 1 H), 2.58 (dd, J ) 16.2, 6.0 Hz, 1 H), 2.83-
5
.85 (m, 1 H), 3.44-3.48 (m, 1 H), 5.55-5.60 (m, 1 H); the
2
protons of minor isomer (18%) were also detected, δ 0.86 (s, 9
tivity 80%; a colorless crystal; bp 120 °C (1.2 mmHg); R
f
)
-1
H), 5.51-5.52 (m, 1 H); IR (neat) 1709 cm ; GC/MS (EI, 70
1
0
(
0
.40 (hexane:AcOEt ) 10:1); H NMR of major isomer (80%)
270 MHz, CDCl ) δ 0.05 (s, 3 H), 0.07 (s, 3 H), 0.12 (s, 9 H),
.74 (s, 3 H), 0.92 (s, 9 H), 1.05 (s, 3 H), 2.10 (s, 3 H), 2.19 (d,
+
eV) m/z (rel int) 406 (M , 3), 73 (100); HRMS for C17
H
27OSi
3
+
t
(M
- OSi BuMe
2
) calcd 275.1831, found 275.1831.
Ack n ow led gm en t. This work was supported by
J ) 16.0 Hz, 1 H), 2.32 (d, J ) 16.0 Hz, 1 H), 2.55-2.57 (m, 2
H), 3.05-3.08 (m, 1 H), 4.11-4.13 (m, 1 H), 5.53-5.55 (m, 1
H); the protons of minor isomer (20%) were also detected, δ
0
5
Grants-in-Aid for Scientific Research (No. 09771916)
from the Ministry of Education, Science and Culture,
J apan.
.14 (s, 9 H), 0.87 (s, 9 H), 2.13 (s, 3 H), 3.86-3.89 (m, 1 H),
-
1
.63-5.67 (m, 1 H); IR (disk) 1705 cm ; GC/MS (EI, 70 eV)
Su p p or tin g In for m a tion Ava ila ble: Spectral data for
+
m/z (rel int) 392 (M , 2), 73 (100). Anal. Calcd for C22
Si : C, 67.28; H, 10.27. Found: C, 67.01; H, 10.30.
-Acetyl-1-[(ter t-bu tyld im eth ylsilyl)oxy]-2,2-d im eth yl-
-(tr im eth ylsilyl)in d a n . This compound (one isomer) was
derived from the treatment of 14 with DBU in air; a colorless
crystal; mp 54.5-55.5 °C (hexane); bp 150 °C (1.2 mmHg); R
H
40
O
2
-
13
2
e-i, C NMR spectral data for 3, 7-10, 12a , and 13-17,
2
13
and C NMR spectra for 14-17 and the aromatized com-
pounds of 14 and 15 (9 pages). This material is contained in
libraries on microfiche, 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.
5
4
f
1
)
0
0.28 (hexane:AcOEt ) 10:1); H NMR (500 MHz, CDCl
3
) δ
.16 (s, 3 H), 0.19 (s, 3 H), 0.28 (s, 9 H), 0.83 (s, 3 H), 0.97 (s,
J O980987B