Highly diastereoselective desymmetrizing intramolecular cyclization of allylstannane with a diketone promoted by Lewis acid or transition metal complex

Article abstract of DOI:10.1016/S0022-328X(00)00897-4

The Lewis acid mediated de symmetrizing intramolecular cyclization of prochiral allylstannyl diketone (1) gave a mixture of two diastereomers (2 and 3). Highly diastereoselective synthesis of each of the diastereomers was accomplished by appropriate choic

Full text of DOI:10.1016/S0022-328X(00)00897-4

Journal of Organometallic Chemistry 624 (2001) 136–142
www.elsevier.nl/locate/jorganchem
Highly diastereoselective desymmetrizing intramolecular cyclization
of allylstannane with a diketone promoted by Lewis acid or
transition metal complex
Takashi Shimada, Naoki Asao, Yoshinori Yamamoto *
Department of Chemistry, Graduate School of Science, Tohoku Uni6ersity, Sendai 980-8578, Japan
Received 4 October 2000; accepted 20 November 2000
Dedicated to Professor Jean Normant on the occasion of his 65th birthday
Abstract
The Lewis acid mediated desymmetrizing intramolecular cyclization of prochiral allylstannyl diketone (1) gave a mixture of two
diastereomers (2 and 3). Highly diastereoselective synthesis of each of the diastereomers was accomplished by appropriate choice
of the Lewis acid. Compound 3 was also produced stereoselectively by using a palladium catalyst instead of Lewis acid. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: Desymmetrizing cyclization; Allylstannane; Diketone; Lewis acid; Transition metal catalyst
tiguous chiral centers with desymmetric cyclization of
the prochiral substrate, both chemical yields and
diastereoselectivities were generally low.
1. Introduction
The condensation of allylstannane with ketones is
one of the most important synthetic methods for C–C
bond formation, and one of the most attractive reac-
tions to construct a quaternary carbon stereocenters [1].
While a number of methods for intramolecular conden-
sation with aldehydes have been studied during last
decade [2], to the best of our knowledge, there are few
reports on the intramolecular condensation of allyl-
metal reagents with ketones [3]. Wu and co-workers
reported the intramolecular allylation of ketone by
using an allylstannane prepared in situ from allyl bro-
mide and tin metal in the presence of mercury chloride,
and succeeded to synthesize the cyclic ether, which has
two chiral centers containing a quaternary carbon stere-
ocenter with moderate diastereoselectivity [3a]. The in-
tramolecular cyclization of cyclic [3b] and acyclic [3c]
b-diketones with allylsilane have been also accom-
plished. While these reactions can construct three con-
Recently, we reported as a preliminary communica-
tion that the Lewis acid mediated intramolecular cy-
clization of prochiral allylstannyl diketone (1) gave a
mixture of two diastereomers (2 and 3), and highly
diastereoselective synthesis of each diastereoisomer was
accomplished by proper choice of the Lewis acids
(Scheme 1) [4]. Now we report the full details on the
previous study along with the palladium catalyzed
stereoselective cyclization of 1.
2. Results and discussion
2.1. Preparation of the substrate 1
The preparation of 1 is shown in Scheme 2. Reaction
of 1,4-butanediol (6) with TBDMSCl/imidazole in
DMF gave the monosilylated alcohol (7) in 86% yield.
Swern oxidation of 7 followed by the treatment with
methyl (triphenylphosphoranylidene)acetate gave the
corresponding a,b-unsaturated ester (8) in 70% yield.
The ester group of 8 was reduced by DIBAL-H, and
* Corresponding author. Tel.: +81-222-176581; fax: +81-222-
176784.
E-mail address: yoshi@yamamoto1.chem.tohoku.ac.jp (Y. Ya-
mamoto).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00897-4

T. Shimada et al. / Journal of Organometallic Chemistry 624 (2001) 136–142
137
Scheme 1.
Scheme 2.
the resulting alcohol was acetylated with acetic anhy-
dride in pyridine. Subsequent treatment with acetic acid
in THF-H2O gave 9 in 94% yield. Bromination of 9 was
performed by CBr4/PPh3 to give 10 in 88% yield. Alky-
lation of 10 with 3-methyl-2,4-pentanedione with NaH
in DMF produced 11 in 80% yield. The palladium-cata-
lyzed reaction of 11 with Et2AlSnBu3 [5] gave 1 in 53%
yield.
instead of TiCl4, the chemical yield decreased to 67%
and the protodestannylated product 12 was obtained in
26% yield (entry 3) [6]. The reactions mediated by AlCl3
and EtAlCl2 also afforded cis–trans isomer 2 as a
major product, but in both cases, the chemical yield
and the diastereoselectivity were lower than those via
the TiCl4 mediated reaction (entries 4 and 5). The
cyclization of 1 did not proceed in the presence of a
weaker Lewis acid such as Et2AlCl (entry 6). Interest-
ingly, the reactions mediated by BF3·OEt2 (entry 7),
ZnBr2 (entry 8), InCl3 (entry 9), and Yb(OiPr)3 (entry
10) afforded cis–cis 3 as a major product in moderate
yields. The use of SnCl4 gave only cis–cis isomer 3 in
66% isolated yield (entry 11). Surprisingly, the use of
0.5 equivalents of SnCl4 afforded 3 in higher yield
(entry 12). On the other hand, the use of protic acid
such as camphorsulfonic acid (CSA) and CF3CO2H
gave only the reduced product 12 in 85 and 89% yield,
respectively (entries 13 and 14). HCl also afforded the
reduced product 12 quantitatively. No thermal reaction
took place even at elevated temperature (toluene,
110°C) in 2 days, and 1 was decomposed in 5 days.
2.2. Lewis acid mediated intramolecular cyclization of
allylstannane with diketone
The Lewis acid mediated cyclization of 1 was exam-
ined (Eq. (1)) and the results are summarized in Table
1. In all cases, only two diastereoisomers, cis–trans 2
and cis–cis 3, were obtained among four possible
stereoisomeric cyclization products (2–5). The reaction
promoted by TiCl4 (1.0 equivalents) gave a 92:8 mix-
ture of cis–trans 2 and cis–cis 3 in 87% isolated yield
(entry 1). The use of 0.5 equivalents of TiCl4 gave two
diastereomers in the yields just corresponding to the
amount of TiCl4 (entry 2). Although the diastereoselec-
tivity of 2 increased up to 95:5 by using TiCl2(OiPr)2

138
T. Shimada et al. / Journal of Organometallic Chemistry 624 (2001) 136–142
product in low yield (entry 5). The chemical yield was
not improved either by using 30, 50 and 100 mol%
amount of palladium or by using other solvents such as
CH2Cl2, DMF, DMSO, toluene, and dioxane.
2.4. Determination of stereostructure
The configurations of the two products were assigned
by 1H-NMR decoupling and NOE experiments. The
coupling constants between Ha and Hb of 2 and 3 were
J=12.5 Hz and J=12.0 Hz, respectively, indicating
that the stereochemical relation between Ha and Hb
were axial–axial in both compounds. Therefore, the
vinyl substituent of both isomers could be assigned to
be equatorial. In cis–trans isomer 2, NOE effects were
observed between a hydroxyl proton and the neighbor-
ing methyl group, between Hb and the methyl group
attached to the carbon of COH, and between these two
methyl groups, indicating that the methyl group at
COH was in the 1,3-diaxial position from Hb. It is clear
that the stereochemical relation between the vinyl and
(1)
2.3. Transition metal catalyzed intramolecular
cyclization of allylstannane with diketone
The reactions catalyzed by several Pd(II) or Pt(II)
complexes were examined and the results are summa-
rized in Table 2. No reaction took place in the absence
of any transition metal catalysts (entry 1). While neither
PdCl2(PPh3)2 nor PtCl2(PPh3)2 catalyzed the cyclization
reaction effectively (entries 2–4), the reaction catalyzed
by (h3-C3H5PdCl)2 gave cis–cis isomer 3 as a major
Table 1
Cyclization of 1 mediated by various Lewis acid and protic acid a
Entry
Promoter (equiv.)
Temp (°C)
Time (h)
Ratio (2:3) b
Yield (%) c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TiCl4 (1.0)
TiCl4 (0.5)
−78
−78
−35
−78
−10
rt
−10
rt
−20
rt
1
1
12
2
2
50
2
96
13
1.3
1
2
16
1
92:8
93:7
95:5
73:27
77:23
87 e
55
TiCl2(OiPr)2 (1.5)
AlCl3 (1.0)
EtAlCl2 (2.0)
Et2AlCl (2.0)
BF3·OEt2 (2.0)
ZnBr2 (1.0)
InCl3 (1.0)
Yb(OiPr)3 (1.0)
SnCl4 (1.0)
67 d
61
66
0
32:68
21:79
3:97
8:92
2:\98
2:\98
29 d
60
55
76
−78
−78 to 0
−40
−78 to −20
66 d
88
SnCl4 (0.5)
CSA (2.0)
CF3CO2H (2.0)
0 d
0 d
a The reactions were carried out with 0.1 M substrate (1 mmol) in CH2Cl2 under the conditions indicated in the table, and quenched with
saturated aqueous NaHCO3 at the reaction temperature.
b Determined by 1H-NMR.
c Determined by 1H-NMR (p-xylene was used as an internal standard).
d The reduced product 12 was obtained as a by-product (entry 3, 26%; entry 7, 10%; entry 13, 85%; entry 14, 89%); see Ref. [6].
e Isolated yield.
Table 2
Transition metal catalyzed cyclization of 1
Entry
Catalyst (10 mol%)
Solvent
Temp (°C)
Time (h)
Ratio (2:3) a
Yield (%) b
1
2
3
4
5
none
THF
THF
THF
CH3CN
CH3CN
50
50
50
50
rt
96
11
120
72
0
trace
0
5
32
PdCl2(PPh3)2
PtCl2(PPh3)2
PtCl2(PPh3)2
(h3-C3H5PdCl)2
2:\98
13: 87
8: 92
19
a Determined by 1H-NMR.
b Determined by 1H-NMR (p-xylene was used as an internal standard).

T. Shimada et al. / Journal of Organometallic Chemistry 624 (2001) 136–142
139
hydroxyl group is trans, and that of hydroxyl and
acetyl group is cis. In cis–cis isomer 3, NOE effects
were observed between Ha and the neighboring methyl
group, and between Ha and the methyl group attached
to the carbon of C(CO)CH3. It is clear that the stereo-
chemical relation between the vinyl and hydroxyl group
is cis, and that of hydroxyl and acetyl group is cis.
2.5. Mechanism
The mechanism for the diastereoselectivity difference
between the TiCl4 mediated and SnCl4 (also InCl3 and
Yb(OiPr)3) mediated reactions has not been unambigu-
ously established. A plausible mechanism is shown in
Scheme 3. When TiCl4 is used as a Lewis acid, a
transmetalation between stannane of 1 and TiCl4 could
Scheme 3.

140
T. Shimada et al. / Journal of Organometallic Chemistry 624 (2001) 136–142
Scheme 4.
4. Experimental
take place and the resulting allyltitanium compound
could undergo cyclization via a cyclic transition state.
Although there are two possibilities for the structure of
cyclic transition state A and B, 1,3-diaxial steric repul-
sion between axial C(O)CH3 and CꢀCH– destabilizes
the transition state B. Therefore, the reaction would
proceed via A. Perhaps the ethylaluminium dichloride
mediated reaction would proceed also via A. On the
other hand, the transmetalation reaction between stan-
nane of 1 and SnCl4 (InCl3 and Yb(OiPr)3) would be
slower, and thus the cyclization would take place via an
acyclic transition state. There are also two possibilities
for the transition state structures; C (synclinal) and D
(antiperiplanar). It was reported that the intramolecular
cyclization of allylstannane with aldehydes would un-
dergo synclinal transition state [2h–i]. Therefore, the
reaction would proceed via C, in which the Lewis acid
would coordinate to carbonyl oxygen and facilitate the
cyclization.
4.1. General
1H- and 13C-NMR spectra were recorded on JEOL
JNM-GSX-270 (270 MHz and 67.9 MHz), JEOL JNM-
AL 300 (300 and 75.5 MHz), or JEOL JNM-A500 (500
and 125.7 MHz) instrument. These spectra data are
reported in the ppm downfield from tetramethylsilane.
The IR spectra were recorded on a Shimadzu FT
IR-8200A spectrometer. The high-resolution mass spec-
tra were recorded on either Hitachi M-2500S or JEOL
JMS-HX-110 spectrometer. Column chromatography
was carried out by employing either Merck silica gel
(Kiesegel 70-230 mesh) or Fuji Silysia Chemical basic
silica gel (Chromatorex NH, 100–200 mesh), and the
analytical thin layer chromatography (TLC) was per-
formed on the 0.2 mm precoated silica gel plates (Kie-
segel 60 F254). All manipulations were conducted under
an argon atmosphere by using the standard Schlenk
techniques. Anhydrous solvents were purchased from
Kanto Chemicals. All other compounds used were com-
mercially available and purchased from Aldrich.
On the other hand, the (h3-C3H5PdCl)2 catalyzed
reaction would probably proceed via a bis-p-allylpalla-
dium complex E in which the allyl group can add
nucleophilically to one of the carbonyl groups (Scheme
4) [6]. The diastereoselective formation of cis–cis iso-
mer 3 might be explained by the preferred formation of
transition state F due to the chelation effect between
palladium and two carbonyl groups. The hypothesis of
the presence of the bis-p-allylpalladium intermediate E
is supported by the fact that no reaction took place
with PdCl2(PPh3)2 and PtCl2(PPh3)2, since those cata-
lysts can not provide allyl unit to form bis-p-allylpalla-
dium from 1.
4.2. Preparation of starting material 1
To a DMF (150 ml) solution of 1,4-butanediol (34 g,
378 mmol) at 0°C were added imidazole (5.8 g, 85
mmol) and TBDMSCl (10.6 g, 70 mmol), and the
mixture was stirred for 2 h at room temperature (r.t.).
Water (150 ml) was added, and the mixture was ex-
tracted with ether, washed with water and brine, dried
with anhydrous MgSO4, and concentrated under re-
duced pressure. The residue 5 was used for further
manipulation without purification. Oxalyl chloride (3.5
ml, 40 mmol) was added dropwise to the mixture of
CH2Cl2 (100 ml) and DMSO (3.5 ml, 50 mmol) at
−78°C under argon and stirred for 20 min. A CH2Cl2
(15 ml) solution of 5 (4.3 g, 21 mmol) was added
dropwise and the mixture was stirred for 1 h at −78°C.
Triethylamine (20 ml, 140 mmol) was added and the
mixture was warmed gradually to r.t. and further
stirred for 1 h at r.t. Addition of excess saturated
aqueous NH4Cl, extraction with ether, washing with
water and brine, drying with anhydrous MgSO4, con-
centration under reduced pressure, and purification
3. Conclusion
Highly diastereoselective desymmetric intramolecular
cyclization of prochiral allylstannyl diketone (1) gives
6-membered carbocycles (2 and 3) with high stereose-
lectivities was accomplished. The cyclization of 1 pro-
duces only two diastereoisomers (2 and 3) among four
possible stereoisomeric cyclization products. Moreover,
highly diastereoselective synthesis of each diastereoiso-
mer was accomplished by proper choice of the Lewis
acid or Pd(II) catalyst.

T. Shimada et al. / Journal of Organometallic Chemistry 624 (2001) 136–142
141
4.3. Procedure for Lewis acid mediated cyclization of 1
with column chromatography (silica gel; n-hexane/ethyl
acetate, 10/1) gave the corresponding aldehyde (3.7 g,
87%). To a toluene (90 ml) solution of aldehyde obtained
above (6.0 g, 30 mmol) at room temperature was added
methyl (triphenylphosphpranyliden)acetate (11.7 g, 35
mmol) and the reaction mixture was stirred for 24 h at
room temperature. Filtration, concentration under re-
duced pressure, purification with column chromatogra-
phy (silica gel; n-hexane/ethyl acetate, 10/1) gave 6 (7.2
g, 93%). 6 dissolved in CH2Cl2 (65 ml), and 1.01 M CH2Cl2
solution of i-Bu2AlH (DIBAL, 61 ml, 62 mmol) was
added dropwise at −78°C in 20 min. The mixture was
stirred for 1.5 h, and water (35 ml) was added slowly. The
mixture was stirred overnight at r.t., dried with anhydrous
MgSO4 and concentrated under reduced pressure. The
residue was dissolved in pyridine (20 ml), and Ac2O (10
ml) was added and the mixture was stirred for 6 h at r.t.
Water was added to the mixture, extracted with ether,
washed with 1 N HCl, water, and brine, dried with
anhydrous MgSO4, concentrated under reduced pressure.
The residue was dissolved in a mixture of THF (60 ml)
and H2O (20 ml), AcOH (20 ml) was added and the
mixture was stirred overnight at r.t. Concentration under
reduced pressure, and purification with column chro-
matography (silica gel; n-hexane/ethyl acetate, 1/1) gave
7 (4.1 g, 93%). To an ether solution of 7 (5.3 g, 34 mmol)
were added PPh3 (15.4 g, 59 mmol), CBr4 (24.6 g, 74
mmol), and the reaction mixture was stirred for 24 h at
room temperature. Filtration, concentration under re-
duced pressure, and purification with column chromatog-
raphy (silica gel; n-hexane/ethyl acetate, 8/1) gave 8 (6.1
g, 88%). To a suspension of NaH (340 mg, 8.5 mmol, 60%
in mineral oil) in DMF (8 ml) at 0°C under argon was
added 3-methyl-2,4-pentanedione (1.0 ml, 8.6 mmol), and
the mixture was stirred for 30 min. A DMF (5 ml) solution
of 8 (1.4 g, 6.5 mmol) and NaI (240 mg, 1.6 mmol) were
added and the resulting mixture was stirred for 6 h at
70–75°C. Addition of water at 0°C, extraction with ether,
washing with water and brine, drying with anhydrous
MgSO4, and concentration under reduced pressure, and
purification with column chromatography (silica gel;
n-hexane/ethyl acetate, 3/1) gave 9 (1.3 g, 77%). To a THF
(50 ml) solution of bis(tributyltin) (10.5 g, 18 mmol) was
added a 1.63 M n-hexane solution of n-BuLi (11.0 ml,
18 mmol) at 0°C, and the mixture was stirred for 20 min.
A 1.0 M n-hexane solution of Et2AlCl (18 ml, 18 mmol)
was added at −78°C and the mixture was stirred for 1
h. Pd(PPh3)4 (700 mg, 0.65 mmol) was added and the
mixture was stirred for 30 min. A THF solution of 9 (3.3
g, 13 mmol) was added and the mixture was stirred for
26 h at r.t. Addition of aqueous NH3, filtration extraction
with ether, washing with water and brine, drying with
anhydrous MgSO4, and concentration under reduced
pressure, and purification with column chromatography
(silica gel; n-hexane/ethyl acetate, 8/1) gave 1 (2.4 g, 53%).
The reaction mediated by TiCl4 is representative. To
a stirred solution of 1 (48.5 mg, 0.1 mmol) in 1 ml of
dry CH2Cl2 under argon at −78°C was added TiCl4
(1.0 M solution in CH2Cl2, 0.1 ml, 0.1 mmol), and the
mixture was stirred for 1 h. The reaction was quenched
with saturated aqueous NaHCO3 solution, extracted
with ether, washed with brine, and dried over MgSO4.
The solvents were removed in vacuo, and the residue
was purified by silica gel column chromatography (n-
hexane/ethyl acetate=8/1). The diastereomer ratio was
1
determined by H-NMR; a 92:8 mixture of 2 and 3 was
obtained in 87% (17.1 mg).
4.4. Procedure for transition metal catalyzed
cyclization of 1
The reaction catalyzed by (h3-C3H5PdCl)2 in CH3CN
is representative. To a stirred solution of allyltributyltin
(50 mg, 0.15 mmol) and 1 (48.5 mg, 0.1 mmol) in 1 ml
of dry CH3CN under argon at r.t. was added (h3-
C3H5PdCl)2 (2 mg, 0.01 mmol), and the mixture was
stirred for 5.5 h at 50°C. The reaction was quenched
through short column (silica gel). Yield and ratios were
determined by 1H-NMR (p-xylene was used as an internal
standard). 32% yield, 2:3=6:94.
4.5. Characterization of products
4.5.1. 7-Acetyl-7-methyl-8-oxo-1-tributylstannyl-
2-nonene (1)
1
Colorless oil: H-NMR (CDCl3 270 MHz) l 5.54 (tt,
J=7.0, 7.0 Hz, 1H), 5.15 (tt, J=7.0, 7.0 Hz, 1H), 2.08
(s, 6H), 1.99 (m, 2H), 1.82 (m, 2H), 1.52–0.80 (m, 31H),
1.30 (s, 3H). MS (EI) m/z 486 (M+, 19), 429 (M+−Bu,
33), 291 (Bu3Sn, 100). HRMS Calc. for C24H46O2Sn
486.2520, Found 486.2525.
4.5.2. (1R*, 2S*, 5R*)-2-Acetyl-1,2-dimethyl-5-
6inylcyclohexanol (2)
Colorless oil: 1H-NMR (CDCl3 500 MHz) l 6.13 (ddd,
J=17.5, 10.5, 6.0 Hz, 1H), 5.09 (ddd, J=10.0, 2.0, 2.0
Hz, 1H), 5.00 (ddd, J=17.5, 2.0, 2.0 Hz, 1H), 4.55 (q,
J=1.2 Hz, 1H). 2.52 (ddd, J=6.0, 6.0, 12.5 Hz, 1H), 2.23
(s, 3H), 2.07 (m, 1H), 1.77–1.70 (m, 2H), 1.57 (ddd,
J=3.8, 14.5, 14.5 Hz, 1H), 1.36 (dddd, J=4.2, 12.0, 12.5,
12.5 Hz, 1H), 1.22 (s, 3H), 1.20 (m, 1H), 1.03 (d, J=1.2
Hz, 3H). HRMS Calc. for C12H20O2 196.1463, Found
196.1473.
4.5.3. (1R*, 2S*, 5S*)-2-Acetyl-1,2-dimethyl-5-
6inylcyclohexanol (3)
Colorless oil: 1H-NMR (CDCl3 500 MHz) l 5.92
(ddd, J=17.0, 10.0, 8.5 Hz, 1H), 5.03 (ddd, J=10.0,
2.2, 0.4 Hz, 1H), 4.99 (ddd, J=17.0, 2.2, 0.8 Hz, 1H),

142
T. Shimada et al. / Journal of Organometallic Chemistry 624 (2001) 136–142
Carbonyl Chemistry, Wiley–VCH, Weinheim, 2000, p. 299. (b)
S.R. Chemler, W.R. Roush, in: J. Otera (Ed.), Modern Carbonyl
Chemistry, Wiley–VCH, Weinheim, 2000, p. 403.
4.32 (s, 1H), 2.20 (s, 3H), 2.15 (ddd, J=4.0, 8.5, 12.0
Hz, 1H), 2.05 (ddd J=13.0, 13.0, 4.5 Hz, 1H), 1.75
(dddd, J=4.5, 12.0, 12.5, 12.5 Hz, 1H), 1.65–1.58 (m,
2H), 1.45–1.38 (m, 2H), 1.30 (s, 3H), 1.13 (s, 3H).
HRMS Calc. for C12H20O2 196.1463, Found 196.1460.
[2] (a) Y. Yamamoto, T. Komatsu, K. Maruyama, J. Chem. Soc.,
Chem. Commun. (1983) 191. (b) T. Kra¨mer, J.R. Schwark, D.
Hoppe, Tetrahedron Lett. 30 (1989) 7037. (c) A. Takuwa, Y.
Nishigaichi, K. Yamashita, H. Iwamoto, Chem. Lett. (1990) 1761.
(d) S.E. Denmark, S. Hosoi, J. Org. Chem. 59 (1994) 5133. (e)
G.E. Keck, S.M. Dougherty, K.A. Savin, J. Am. Chem. Soc. 117
(1995) 6210. (f) C.J. Li, Y.Q. Lu, Tetrahedron Lett. 36 (1995)
2721. (g) M. Yasuda, Y. Sugawa, A. Yamamoto, I. Shibata, A.
Baba, Tetrahedron Lett. 37 (1996) 5951. (h) I. Kadota, M.
Kawada, V. Gevorgyan, Y. Yamamoto, J. Org. Chem. 62 (1997)
7439. (i) S.E. Denmark, E.J. Weber, J. Am. Chem. Soc. 106
(1984) 7970.
[3] (a) J.Y. Zhou, Z.G. Chen, S.H. Wu, J. Chem. Soc., Chem.
Commun. (1994) 2783. (b) D. Schinzer, G. Panke, J. Org. Chem.
61 (1996) 4496. (c) G.A. Molander, S.W. Andrews, Tetrahedron
44 (1988) 3869.
[4] T. Shimada, Y. Yamamoto, Tetrahedron Lett. 39 (1998) 471.
[5] B.M. Trost, J.W. Herndon, J. Am. Chem. Soc. 106 (1984) 6835.
[6] Destannylated diketone 1 2 was obtained as a by-product.
4.5.4. 3–Acetyl–3–methyl–2-oxo-8-nonene (12)
Colorless oil: 1H-NMR (CDCl3 270 MHz) l 5.77
(ddt, J=16.5, 10.0, 6.5 Hz, 1H), 4.99 (ddt, J=16.5,
1.7, 2.0 Hz, 1H), 4.94 (ddt, J=10.0, 1.7, 2.0, 1H), 2.10
(s, 6H), 2.05 (dt, J=6.5, 6.5 Hz, 2H), 1.83 (m, 2H),
1.41 (tt, J=7.5, 7.5 Hz, 2H), 1.31 (s, 3H), 0.92 (t.
J=7.0 Hz, 2H). 13C NMR (CDCl3 75.45 MHz) l
207.5, 138.4, 114.7, 66.7, 34.0, 33.3, 29.2, 26.5, 23.5,
17.9. MS (EI) m/z 196 (M+, 1), 154 (M+−CH3CO, 6),
43 (CH3CO, 100). HRMS Calc. for C24H46O2Sn
196.1463, Found 196.1473.
References
[1] (a) S.E. Denmark, N.G. Almstead, in: J. Otera (Ed.), Modern
.