Silylcuprates from allene and their reaction with α,β- unsaturatedd nitriles and imines. Synthesis of silylated oxo compounds leading to cyclopentane and cycloheptane ring formation

Article abstract of DOI:10.1021/jo0509814

The silylcupration of allenes and the subsequent capture of the intermediate cuprate with α,β-unsaturated nitriles is reported. The influence of the substitution of the nitrile, the nature of the silylcopper species, and the temperature on the selectivity

Full text of DOI:10.1021/jo0509814

Silylcuprates from Allene and Their Reaction with
r,â-Unsaturatedd Nitriles and Imines. Synthesis of Silylated Oxo
Compounds Leading to Cyclopentane and Cycloheptane Ring
Formation
Asuncio´n Barbero, Yolanda Blanco, and Francisco J. Pulido*
Departamento de Quı´mica Orga´nica, Universidad de Valladolid, 47011 Valladolid, Spain
pulido@qo.uva.es; barbero@qo.uva.es
Received May 17, 2005
The silylcupration of allenes and the subsequent capture of the intermediate cuprate with R,â-
unsaturated nitriles is reported. The influence of the substitution of the nitrile, the nature of the
silylcopper species, and the temperature on the selectivity of the reaction is studied. An interesting
diaddition process was observed (1,2-addition and 1,4-addition), leading to oxo compounds which
simultaneously have an allylsilane and a vinylsilane group. The different reactivity of these two
units has been employed in the intramolecular allylsilane-terminated cyclization of these adducts,
where the vinylsilane moiety remains unchanged. To shed some light on the reaction pathway, the
behavior of R,â-unsaturatedd imines was also checked and a new and convenient way for
cycloheptane annulation presented. In light of the former results a feasible mechanism is proposed.
Introduction
allenes provides an easy entry to the synthesis of allyl-
and vinylsilanes,3 since it allows the introduction of two
different metals (Si and Cu) across a C-C multiple bond.
It has been shown that the silylcupration of allenes
occurs syn-stereospecifically,4 giving rise to the formation
of intermediate cuprates, which react with electrophiles
to afford either vinyl- or allylsilanes. The regiochemistry
of the addition depends on various factors such as the
nature of the cuprate, the substitution of the allene, the
temperature of the reaction, and the nature of the silyl
group. Thus, the reaction of 1,2-propadiene with higher
order silylcyanocuprates 1 containing the dimethyl-
phenylsilyl group gives,5,6 at any temperature between
-78 and 0 °C, a vinylsilane-allylcuprate intermediate
2, which readily reacts with a wide variety of electro-
Organosilanes are interesting building blocks in or-
ganic synthesis due to the large number of transforma-
tions that the C-Si bond can undergo.1 Among them
allyl- and vinylsilanes have gained considerable impor-
tance as usual synthetic intermediates in organic syn-
thesis. Silylmetalation of multiple bonds is one of the
most attractive strategies for the efficient synthesis of
these compounds.2 In particular the silylcupration of
(1) (a) Fleming, I. In Comprehensive Organic Synthesis; Trost, B.
M., Fleming, I., Eds; Pergamon: Oxford, 1991; Vol. 2, pp 563-593. (b)
Davies, A. G. In Comprehensive Organometallic Chemistry II; Perga-
mon: New York, 1995; Vol. 2, p 217.
(2) (a) Sharma, S.; Oehlschlager, A. C. J. Org. Chem. 1991, 56, 770-
776. (b) Fugami, K.; Hibino, J.; Nakatsukasa, S.; Matsubara, S.;
Oshima, K.; Utimoto, K.; Nozaki, H. Tetrahedron 1988, 44, 4277-4292.
(c) Arnold, J.; Engeler, M. P.; Elsner, F. H.; Heyn, R. H.; Tilley, T. D.
Organometallics 1989, 8, 2284-2286. (d) Wu, M.-Y.; Yang, F.-Y.;
Cheng, C.-H. J. Org. Chem. 1999, 64, 2471-2474. (e) Horn, K. A. Chem.
Rev. 1995, 95, 1317-1350. (f) Sharma, H. K.; Pannell, K. H. Chem.
Rev. 1995, 95, 1351-1374. (g) Suginome, M.; Matsuda, T.; Nakamura,
H.; Ito, Y. Tetrahedron 1999, 55, 8787-8800. (h) Suginome, M.; Ito,
Y. J. Organomet. Chem. 2003, 43-50. (i) Krause, N. Modern Organo-
copper Chemistry; Wiley-VCH: Dortmund, 2002; pp 93-102.
(3) Barbero, A.; Pulido, F. J. Acc. Chem. Res. 2004, 37, 817-825.
(4) Fleming, I.; Landais, Y.; Raithby, P. R. J. Chem. Soc.; Perkin
Trans 1 1991, 715-719.
(5) Fleming, I.; Pulido, F. J. J. Chem. Soc.; Chem. Commun. 1986,
1010-1011.
(6) Fleming, I.; Rowley, M.; Cuadrado, P.; Gonza´lez-Nogal, A. M.;
Pulido, F. J. Tetrahedron 1989, 45, 413-424.
10.1021/jo0509814 CCC: $30.25 © 2005 American Chemical Society
Published on Web 07/26/2005
6876
J. Org. Chem. 2005, 70, 6876-6883

Silylcupration of Allenes with Nitriles and Imines
TABLE 1. Silylcupration of Allenes and Reaction with
Alkenenitriles Using the Lower Order Cuprate 3
SCHEME 1
SCHEME 2
philes, leading to the corresponding vinylsilanes (Scheme
1).
Interestingly the use of a lower order cuprate, the
(dimethylphenylsilyl)cuprate reagent 3, in an analogous
addition to allene, provides a completely different regio-
chemistry pattern.7 The reaction now shows temperature
dependence, giving the vinylsilane-allylcopper interme-
diate 4, at 0 °C, and the allylsilane-vinylcopper inter-
mediate 5, at -40 °C, which might account for the
reversibility of the reaction. This result has great interest
since it opens a route for the synthesis of functionalized
allylsilanes, by reaction of 5 with electrophiles (Scheme
2).
a Ratio cuprate:nitrile ) 2:1. b Yield of isolated product referred
to nitrile.
Organocopper reagents are relatively unreactive to-
ward alkenenitriles.9 Particularly reactive cuprates are
generally required for efficient organocopper additions
to these substrates. Thus reaction of the higher order
cuprate Me2CuLi‚LiCN with R,â-unsaturatedd nitriles
causes 1,2-addition,10 whereas addition of trimethylsilyl
chloride ((TMS)Cl) redirects the reaction toward double
1,2- and 1,4-addition.11 Boron-containing cuprate re-
agents promote conjugate additions to alkenenitriles with
moderated yields.12
The reaction of the lower order silylcopper reagent 3,
prepared by stirring at 0 °C 1 equiv of (dimethylphenyl-
silyl)lithium and copper(I) cyanide in tetrahydrofuran
(THF) for 30 min, with allene at -78 °C for 1 h, followed
by addition of BF3‚OEt2 and subsequent slow addition
of nitriles 6a-k (-78 to 0 °C) affords the ketones 7a-k
and 8i-k (Table 1). The reaction (one pot) is clean and
high-yielding and seems to be produced by addition of
the allylcopper species 4 to the nitrile and conjugate
addition of the vinylcopper species 5 to the double bond.
The most obvious explanation for these results is a
reversible reaction, with the vinylcopper species 5 being
Results and Discussion
In general the reactive species at low temperature is
5. Thus, at -40 °C, R,â-unsaturatedd oxo compounds
react with 5 to give exclusively the products of Michael
addition. However, at -40 °C saturated ketones are
unreactive toward species 5, but they readily react with
4 as the temperature warms to 0 °C, giving now the
vinylsilane resulting from 1,2-addition. These results
account for the rapid interconversion between species 4
and 5 as the temperature increases. Surprisingly, when
the electrophile used is an unsaturatedd nitrile, diaddi-
tion of both species can occur.
We now report the full results8 of an unusual tandem
diaddition process of the copper species 4 and 5 to R,â-
unsaturatedd nitriles to give products which have both
an allylsilane group and a vinylsilane group.
(9) Fleming, F. F.; Wang, Q. Chem. Rev. 2003, 103, 2035-2077.
(10) Lipshutz, B. H.; Wilhelm, R. S.; Kozlowski, J. A. J. Org. Chem.
1984, 49, 3938-3942.
(7) Blanco, F. J.; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J.;
Fleming, I. Tetrahedron Lett. 1994, 35, 8881-8882.
(8) Preliminary results: Barbero, A.; Blanco, Y.; Pulido, F. J. Chem.
Commun. 2001, 1606-1607.
(11) Alexakis, A.; Berlan, J.; Besace, Y. Tetrahedron Lett. 1986, 27,
1047-1050.
(12) Yamamoto, Y.; Yamamoto, S.; Yatagai, H.; Ishihara, Y.; Maruya-
ma, K. J. Org. Chem. 1982, 47, 119-126.
J. Org. Chem, Vol. 70, No. 17, 2005 6877

Barbero et al.
TABLE 2. Dependence of the Reaction with
SCHEME 3
Temperature
entrya
temp (°C)
product (ratio)
yieldb (%)
1
2
3
4
-78 f 0
-50 f 0
-78 f -50
0
7i + 8i (2:1)
81
73
78
61
7i + 8i (1:1)
7i
8i
a Ratio cuprate:nitrile ) 2:1. b Referred to converted nitrile.
TABLE 3. Reaction with Alkenenitriles at 0 °C
the kinetic intermediate (-78 to -40 °C), and the
allylcopper species 4 being the thermodynamic interme-
diate (-40 to 0 °C). The preference of species 5 for
Michael addition and of species 4 for 1,2 addition must
be related to the higher hardness of cuprate 4 toward 5.
As can be observed in Table 1, alkenenitriles fall into
three groups: alkenenitriles 6a-d, which are good
Michael acceptors, give regioselectively the products of
double 1,2- and 1,4-addition 7a-d (entries 1-4). However
less reactive alkenenitriles 6e-h give regioselectively the
products of 1,2-monoaddition 8e-h (entries 5-8) prob-
ably due to alkyl substitution, which simultaneously
leads to electronic and steric deactivation toward conju-
gate addition. Finally, nitriles 6i-k, having an interme-
diate electronic character, give mixtures of the product
of double and monoaddition, being the major one, in every
case, the product of diaddition (entries 9-11).
Regarding the diaddition products, the order in which
the two steps of addition (1,2 and 1,4) take place is not
totally certain. It seems feasible, in view of the absence
of 1,4-monoaddition products, that the reaction proceeds
by initial addition of species 4 to the nitrile, followed by
conjugate addition of species 5 to the intermediate R,â-
unsaturatedd ketimine (Scheme 3). Further support for
this mechanistic pathway is the easy reaction of R,â-
unsaturatedd imines with 5 (see below, Table 5) and the
fact that the intermediate of the silylcupration of allene,
using the lower order cuprate 3, is unreactive toward the
pentanenitrile enolate (prepared by reaction of pen-
tanenitrile with lithium diisoprpylamide (LDA), at -78
°C, 30 min). The latter result seems to discard the
opposite order of addition (first A1,4 and second A1,2).
Effectively, the second step of this sequence (1,2-addition
of 4 to the resulting intermediate, formally a nitrile
enolate) does not seem very probable in view of the
unsuccessful result obtained with pentanenitrile. (Scheme
3).
entrya
alkenenitrile
product
yieldb (%)
1
2
3
4
6d
6i
6j
6k
8d
8i
8j
8k
58
61
59
64
a Ratio nitrile:cuprate ) 1:1. b Isolated product.
at 0 °C (for 1 h, quenching at that temperature) only the
1,2-addition product 8i was obtained (entry 4).
These results reinforce the mechanistic proposal since
they show that, under thermodynamic conditions, cu-
prate 4 is the only species present, being the monoaddi-
tion 1,2 product obtained. However under kinetic condi-
tions, even though cuprate 5 is the major one in the
equilibrium, the product of double addition is obtained
through an initial and rapid 1,2-addition of the minor
cuprate 4 and subsequent addition of 5.
The selective generation of the product of 1,2-mono-
addition at 0 °C was shown to be general for other
nitriles, as seen in Table 3. This selectivity is also found
when the ratio of nitrile to cuprate is 2:1.
The influence of the nature of the silylcuprate in the
selectivity of the reaction was also examined. Thus
reaction of the higher order silylcopper reagent 1 with
allene at -78 °C for 1 h, followed by addition of BF3‚
OEt2 and subsequent slow addition of nitriles 6b-d,i,k
(-78 to 0 °C) affords the ketones 7c,d,i,k and 8b-d,i,k
(Table 4).
Now the product of 1,2-addition is the only or a major
isomer, which is consistent with the allylcopper inter-
mediate 2 being the major species in the equilibrium
(Scheme 1).
Moreover, the selectivity of the reaction (double addi-
tion versus 1,2-addition) depends also upon the temper-
ature of the process (Table 2). Thus the reaction of nitrile
6i with the intermediate of the silylcupration of allene
(4 and/or 5) gives a 2:1 mixture of 7i and 8i when the
reaction is carried out at -78 °C, warming up from -78
to 0 °C (entry 1). However when the reaction was
repeated from -78 to -50 °C, quenching the intermediate
at -50 °C, the diaddition product 7i was obtained
exclusively (entry 3). And when the reaction was done
To corroborate the mechanistic proposal and the exist-
ence of an intermediate imine (Scheme 3), we studied the
silylcupration of allene with the lower order cuprate 3
and the reaction of the intermediate cuprate with R,â-
unsaturatedd imines 9a-d. The reaction leads with high
yields to the corresponding oxoallylsilanes 10a-d (Table
5). Moreover this methodology constitutes an alternative
to the synthesis of these interesting aldehydes, which are
not readily available by silylcupration of allene and
6878 J. Org. Chem., Vol. 70, No. 17, 2005

Silylcupration of Allenes with Nitriles and Imines
TABLE 4. Silylcupration of Allenes and Reaction with
Alkenenitriles Using the Higher Order Cuprate 1
entrya
alkenenitrile
product
yieldb (%)
1
2
3
4
5
6b, R1 ) H, R2 ) Me
6c, R1 ) H, R2 ) Cl
6d, R1 ) Me, R2 ) H
6i, R1 ) Et, R2 ) H
6k, R1 ) Ph, R2 ) H
8b
75
72
65
68
60
7c + 8c (1:4)
7d + 8d (1:2)
7i + 8i (1:2)
7k + 8k (1:2)
a Ratio nitrile:cuprate ) 1:2. b Isolated product.
TABLE 5. Reaction with r,â -Unsaturatedd Imines
FIGURE 1. X-ray crystal structure of [3S*,5S*]-6-[(dimeth-
ylphenylsilyl)methyl]-5-phenyl-1,6-heptadien-3-ol.
SCHEME 4
entry
imine
product
yield (%)
1
2
3
4
9a, R ) H
9b, R ) Me
9c, R ) nPr
9d, R ) Ph
10a, R ) H
10b, R ) Me
10c, R ) nPr
10d, R ) Ph
84
65
77
79
SCHEME 5
TABLE 6. Synthesis of Allylic Alcohols
entry
aldehyde
product
yield (%)
1
2
3
4
10a, R ) H
10b, R ) Me
10c, R ) nPr
10d, R ) Ph
11a, R ) H
11b, R ) Me
11c, R ) nPr
11d, R ) Ph
95
89
90
87
Oxidation of 11 gave the corresponding enones 12,
which were subjected to Lewis acid-catalyzed cyclization,
leading in good yield to methylenecycloheptanones 13
(Scheme 4).
reaction with R,â -unsaturatedd aldehydes due to isomer-
ization processes.13
Moreover, diadducts 7 containing a nucleophilic allyl-
silane unit and an electrophilic carbonyl moiety undergo
intramolecular allylsilane-terminated cyclization when
treated with a Lewis acid, while the vinylsilane unit
remains unchanged. The reaction leads with high yields
to methylenecyclopentanols 14 and 15 (Scheme 5).
The stereoselectivity of the reaction is not high unless
a phenyl group is present in the molecule, which might
indicate the competitiveness between two relatively bulky
groups (vinylsilane moiety and carbonyl complexed with
the Lewis acid) for the equatorial position in the transi-
tion states 16 or 17 where the R group attains an
equatorial conformation13b (Chart 1).
Oxoallylsilanes 10 can be seen as precursors of seven-
membered rings, which are useful units since they
constitute the structure core of a large number of biologi-
cally important natural products,14 such as karaha-
naenone or perforenone. Their synthesis is accomplished
in three steps from 10. Thus, reaction of aldehydes 10
with vinylmagnesium bromide affords in excellent yield
allylic alcohols 11, as a mixture of two diastereoisomers
(Table 6).
In the case of alcohols 11d both isomers can be
separated by chromatography, one of them being a solid,
the X-ray image of which is showed in Figure 1.
(13) (a) Barbero, A.; Garc´ıa, C.; Pulido, F. J. Tetrahedron Lett. 1999,
40, 6649-6652. (b) Barbero, A.; Garc´ıa, C.; Pulido, F. J. Tetrahedron
2000, 56, 2739-2751.
(14) (a) Yet, L. Chem. Rev. 2000, 100, 2963-3007. (b) Devon, T. K.;
Scott, A. I. Handbook of naturally ocurring compounds; Academic
Press: New York and London, 1972; Vol. II.
Conclusions
In summary, silylcupration of allenes and reaction with
R,â -unsaturated nitriles leads to the products of 1,2-
addition or to the diaddition adducts, depending on the
J. Org. Chem, Vol. 70, No. 17, 2005 6879

Barbero et al.
(6H, s), 0.34 (6H, s). 13C NMR (CDCl3): δ 212.1 (C), 143.8 (C),
143.5 (C), 138.5 (C), 137.5 (C), 134.0 (CH), 133.6 (CH), 130.5
(CH2), 129.1 (CH), 129.0 (CH), 127.8 (CH), 110.3 (CH2), 48.6
(CH2), 43.6 (CH), 41.3 (CH2), 25.5 (CH2), 16.0 (CH3), -2.9
(CH3), -3.0 (CH3). MS: m/z 420 (M+, 3), 405 (M+ - CH3, 7),
343 (M+ - Ph, 10), 285 (M+ - SiMe2Ph, 20), 135 (SiMe2Ph,
100). Anal. Calcd for C26H36OSi2: C, 74.22; H, 8.62. Found:
C, 74.53; H, 8.89.
CHART 1
(e)
5-Chloro-2-(dimethylphenylsilyl)-7-[(dimethyl-
phenylsilyl)methyl]-octa-1,7-dien-4-one (7c). Colorless oil.
IR (neat, cm-1): 1707, 1630, 1240, 1110. H NMR (CDCl3): δ
1
substituents of the nitrile, the temperature, and the
nature of the silylcuprate. The products of double addi-
tion resulting from consecutive 1,2- and 1,4-addition show
two silyl moieties (an allylsilane group and a vinylsilane
group) with a very different reactivity pattern. Thus,
these compounds undergo intramolecular cyclization
processes in the presence of a Lewis acid, where the
vinylsilane moiety remains unchanged. R,â -Unsaturated
imines, in the same conditions, give oxoallylsilanes which
can be easily converted to methylenecycloheptanones in
high yields.
7.51-7.20 (10H, m), 5.71 (1H, d, J ) 2.2 Hz), 5.63 (1H, d, J )
2.2 Hz), 4.64 (1H, s), 4.62 (1H, s), 4.15 (1H, dd, J ) 8.8 and
5.7 Hz), 3.36 (1H, d, J ) 16.8 Hz), 3.28 (1H, d, J ) 16.8 Hz),
2.35 (1H, dd, J ) 15.1 and 5.7 Hz), 2.17 (1H, dd, J ) 15.1 and
8.8 Hz), 1.75 (1H, d, J ) 13.6 Hz), 1.66 (1H, d, J ) 13.6 Hz),
0.38 (6H, s), 0.31 (6H, s). 13C NMR (CDCl3): δ 202.3 (C), 142.6
(C), 141.2.5 (C), 138.3 (C), 137.1 (C), 134.0 (CH), 133.5 (CH),
131.3 (CH2), 129.2 (CH), 127.8 (CH), 111.9 (CH2), 60.0 (CH),
46.0 (CH2), 41.4 (CH2), 25.7 (CH2), -3.0 (CH3-Si). MS: m/z
440 (M+, 5), 286 (M+ - 2×Ph, 12), 271 (M+ - 2×Ph-CH3, 100).
Anal. Calcd for C25H33ClOSi2: C, 68.06; H, 7.54. Found: C,
68.38; H, 7.81.
(f) 2-(Dimethylphenylsilyl)-7-[(dimethylphenylsilyl)-
methyl]-6-methylocta-1,7-dien-4-one (7d). Colorless oil. IR
(neat, cm-1): 1680, 1580, 1240, 1110. 1H NMR (CDCl3): δ
7.53-7.27 (10H, m), 5.73 (1H, d, J ) 2.4 Hz), 5.62 (1H, d, J )
2.4 Hz), 4.55 (1H, s), 4.51 (1H, s), 3.09 (2H, s), 2.40-2.29 (2H,
m), 2.18-2.08 (1H, dd, J ) 15.2 and 7.8 Hz), 1.74 (1H, d, J )
13.9 Hz), 1.67 (1H, d, J ) 13.9 Hz), 0.87 (3H, d, J ) 6.7 Hz),
0.39 (6H, s), 0.32 (6H, s). 13C NMR (CDCl3): δ 208.1 (C), 151.0
(C), 143.6 (C), 139.0 (C), 137.4 (C), 134.0 (CH), 133.6 (CH),
130.6 (CH2), 129.2 (CH), 129.0 (CH), 127.8 (CH), 127.7 (CH),
106.6 (CH2), 50.5 (CH2), 48.4 (CH2), 36.1 (CH), 25.1 (CH2), 19.4
(CH3), -2.8 (CH3), -2.9 (CH3). MS: m/z 420 (M+, 5), 405 (M+
- CH3, 7), 343 (M+ - Ph, 10), 135 (SiMe2Ph, 100). Anal. Calcd
for C26H36OSi2: C, 74.22; H, 8.62. Found: C, 74.66; H, 8.95.
(g) 6-Ethyl-2-(dimethylphenylsilyl)-7-[(dimethylphen-
ylsilyl)methyl]-octa-1,7-dien-4-one (7i). Colorless oil. IR
(neat, cm-1): 1695, 1630, 1240, 1110. 1H NMR (CDCl3): δ
7.55-7.23 (10H, m), 5.73 (1H, d, J ) 2.5 Hz), 5.6 (1H, d, J )
2.5 Hz), 4.59 (1H, s), 4.55 (1H, s), 3.10 (2H, s), 2.26-2.11 (3H,
m), 1.68 (2H, s), 1.29-1.22 (2H, m), 0.72 (3H, t, J ) 7.3 Hz),
0.40 (6H, s), 0.33 (6H, s). 13C NMR (CDCl3): δ 208.2 (C), 148.6
(C), 143.6 (C), 139.1 (C), 137.4 (C), 134.0 (CH), 133.6 (CH),
130.6 (CH2), 129.2 (CH), 129.0 (CH), 127.8 (CH), 127.7 (CH),
108.4 (CH2), 50.5 (CH2), 46.4 (CH2), 43.0 (CH), 25.8 (CH2), 24.6
(CH2), 11.3 (CH3), -2.6 (CH3), -2.7 (CH3). MS: m/z 357 (M+
- Ph, 5), 299 (M+ - SiMe2Ph, 12), 135 (SiMe2Ph, 100). Anal.
Calcd for C27H38OSi2: C, 74.59; H, 8.81. Found: C, 74.98; H,
9.11.
Experimental Section
Silylcupration of Allene. (a) Preparation of Interme-
diates 4 + 5. A solution of (dimethylphenylsilyl)lithium (6
mmol) in THF was added by syringe to a stirred suspension
of copper(I) cyanide (6 mmol) in THF at 0 °C. After 30 min at
this temperature the solution of (dimethylphenylsilyl)copper
3 (6 mmol) was cooled at -78 °C and a slight excess of allene
was added from a balloon. The mixture was stirred for 1 h
and then used immediately.
(b) Reaction of Intermediates 4 + 5 with r,â-Unsatur-
ated Nitriles. (1) Procedure A. BF3.Et2O (6 mmol) was
added at -78 °C to the solution previously prepared and the
mixture stirred for an additional period of 10 min. The nitrile
(3 mmol) in THF was slowly dropped in at -78 °C and stirred
at this temperature for 1 h. The reaction mixture was left to
warm to 0 °C, quenched with basic saturated ammonium
chloride solution, and extracted with ether. The organic layer
was dried (MgSO4), evaporated, and chromatographed to give
the corresponding products (Table 1).
(2) Procedure B. The nitrile (3 mmol) in THF was slowly
dropped in at 0 °C to the solution previously prepared and
the mixture stirred for an additional period of 1 h. The reaction
mixture was quenched with basic saturated ammonium chlo-
ride solution and extracted with ether. The organic layer was
dried (MgSO4), evaporated, and chromatographed to give the
corresponding products (Table 3).
(h) cis-2-[1-(Dimethylphenylsilyl)methyl]ethenylcyclo-
pentyl 2-(Dimethylphenylsilyl)-2-propenyl Ketone (7j).
Colorless oil. IR (neat, cm-1): 1695, 1620, 1240, 1100. 1H NMR
(CDCl3): δ 7.54-7.27 (10H, m), 5.70 (1H, d, J ) 2.3 Hz), 5.61
(1H, d, J ) 2.3 Hz), 4.59 (1H, s), 4.51 (1H, s) 3.17 (2H, s), 2.77
(1H, m), 2.57 (1H, q, J ) 8.3 Hz), 1.80-1.35 (6H, m), 1.70 (2H,
s), 0.39 (6H, s), 0.33 (6H, s). 13C NMR (CDCl3): δ 210.9 (C),
148.7 (C), 143.7 (C), 139.0 (C), 137.5 (C), 134.0 (CH), 133.9
(CH), 133.6 (CH), 130.5 (CH2), 129.1 (CH), 129.0 (CH), 127.7
(CH), 107.2 (CH2), 55.3 (CH), 50.2 (CH), 49.7 (CH2), 32.4 (CH2),
30.0 (CH2), 24.8 (CH2), 24.7 (CH2), -2.7 (CH3), -3.0 (CH3).
MS: m/z 446 (M+, 5), 431 (M+ - CH3, 7), 369 (M+ - Ph, 10),
311 (M+ - SiMe2Ph, 15), 135 (SiMe2Ph, 100). Anal. Calcd for
C28H38OSi2: C, 75.27; H, 8.57. Found: C, 75.58; H, 8.84.
(i) 2-(Dimethylphenylsilyl)hepta-1,5-dien-4-one (8d).
Colorless oil. IR (neat, cm-1): 1650, 1600, 1240, 1110. 1H NMR
(CDCl3): δ 7.54-7.27 (5H, m), 6.70 (1H, dq, J ) 15.6 and 6.9
Hz), 6.03 (1H, d, J ) 15.6 Hz), 5.74 (1H, d, J ) 1.2 Hz), 5.61
(1H, d, J ) 1.2 Hz), 3.28 (2H, s), 1.81 (3H, d, J ) 6.9 Hz), 0.43
(3H, s), 0.39 (3H, s). 13C NMR (CDCl3): δ 191.4 (C), 156.5 (C),
143.2 (CH), 136.4 (C), 134.6 (CH), 134.0 (CH), 131.2 (CH2),
(c) 2-(Dimethylphenylsilyl)-7-[(dimethylphenylsilyl)-
methyl]octa-1,7-dien-4-one (7a). Colorless oil. IR (neat,
cm-1): 1705, 1630, 1240, 1110. 1H NMR (CDCl3): δ 7.55-7.35
(10H, m), 5.75 (1H, d, J ) 2.2 Hz), 5.64 (1H, d, J ) 2.2 Hz),
4.52 (2H, s), 3.14 (2H, s), 2.34 (2H, t, J ) 7.7 Hz), 2.02 (2H, t,
J ) 7.7 Hz), 1.74 (2H, s), 0.41 (6H, s), 0.33 (6H, s). 13C NMR
(CDCl3): δ 208.4 (C), 145.6 (C), 143.6 (C), 138.8 (C), 137.3 (C),
134.0 (CH), 133.5 (CH), 130.5 (CH2), 129.2 (CH), 129.0 (CH),
127.8 (CH), 127.7 (CH), 107.8 (CH2), 50.1 (CH2), 40.4 (CH2),
31.8 (CH2), 26.2 (CH2), -3.0 (CH3), -3.1 (CH3). MS: m/z 406
(M+, 5), 329 (M+ - Ph, 10), 271 (M+ - SiMe2Ph, 13), 135
(SiMe2Ph, 100). Anal. Calcd for C25H34OSi2: C, 73.83; H, 8.43.
Found: C, 74.18; H, 8.71.
(d) 2-(Dimethylphenylsilyl)-7-[(dimethylphenylsilyl)-
methyl]-5-methylocta-1,7-dien-4-one (7b). Colorless oil. IR
(neat, cm-1): 1695, 1640, 1240, 1110. 1H NMR (CDCl3): δ
7.56-7.27 (10H, m), 5.70 (1H, d, J ) 2.6 Hz), 5.63 (1H, d, J )
2.6 Hz), 4.58 (2H, s), 3.17 (1H, d, J ) 16.4 Hz), 3.10 (1H, d, J
) 16.4 Hz), 2.61-2.53 (1H, m), 2.12 (1H, dd, J ) 14.3 and 6.3
Hz), 1.72 (1H, d, J ) 13 Hz), 1.70 (1H, dd, J ) 14.3 and 4.4
Hz), 1.65 (1H, d, J ) 13 Hz), 0.88 (3H, d, J ) 6.7 Hz), 0.40
6880 J. Org. Chem., Vol. 70, No. 17, 2005

Silylcupration of Allenes with Nitriles and Imines
129.4 (CH), 127.9 (CH), 65.5 (CH2), 18.3 (CH3), -3.2 (CH3),
-3.8 (CH3). MS: m/z 229 (M+ - CH3, 100), 135 (SiMe2Ph, 32).
Anal. Calcd for C15H20OSi: C, 73.71; H, 8.25. Found: C, 73.98;
H, 8.51.
(p) 2-(Dimethylphenylsilyl)-6-phenylhexa-1,5-dien-4-
one (8k). Colorless oil. IR (neat, cm-1): 1650, 1600, 1240,
1110. 1H NMR (CDCl3): δ 7.59-7.37 (11H, m), 6.64 (1H, d, J
) 16.1 Hz), 5.82 (1H, d, J ) 2.2 Hz), 5.68 (1H, d, J ) 2.2 Hz),
3.42 (2H, s) 0.40 (6H, s). 13C NMR (CDCl3): δ 198.5 (C), 143.9
(C), 142.7 (CH), 137.3 (C), 134.4 (C), 134.0 (CH), 130.4 (CH),
130.3 (CH2), 129.2 (CH), 128.8 (CH), 128.3 (CH), 127.9 (CH),
125.4 (CH), 48.2 (CH2), -3.2 (CH3). MS: m/z 291 (M+ - CH3,
17), 229 (M+ - Ph, 19), 135 (SiMe2Ph, 100). Anal. Calcd for
C20H22OSi: C, 78.38; H, 7.24. Found: C, 78.69; H, 7.51.
Silylcupration of Allene and Reaction with r,â-
Unsaturated Nitriles Using Cuprate 1. A solution of
(dimethylphenylsilyl)lithium (12 mmol) in THF was added by
syringe to a stirred suspension of copper(I) cyanide (6 mmol)
in THF at 0 °C. After 30 min at this temperature, the solution
of bis(dimethylphenylsilyl)cuprate 1 (6 mmol) was cooled at
-78 °C and a slight excess of allene was added from a ballon.
The mixture was stirred for 1 h and then used immediately.
BF3‚Et2O (6 mmol) was added at -78 °C to the solution
previously prepared and the mixture stirred for an additional
period of 10 min. The nitrile (3 mmol) in THF was slowly
dropped in at -78 °C and stirred at this temperature for 1 h.
The reaction mixture was left to warm to 0 °C, quenched with
basic saturated ammonium chloride solution, and extracted
with ether. The organic layer was dried (MgSO4), evaporated,
and chromatographed to give the corresponding products
(Table 4).
(j) 2-(Dimethylphenylsilyl)-5-ethylhepta-1,5-dien-4-one
(8e). Colorless oil. IR (neat, cm-1): 1675, 1640, 1250, 1095,
909. 1H NMR (CDCl3): δ 7.55-7.27 (5H, m), 6.45 (1H, q, J )
7.0 Hz), 5.66 (1H, d, J ) 2.1 Hz), 5.56 (1H, d, J ) 2.1 Hz),
3.39 (2H, s), 2.24 (2H, q, J ) 7.6 Hz), 1.77 (3H, d, J ) 7.0 Hz),
0.88 (3H, t, J ) 7.6 Hz), 0.39 (6H, s). 13C NMR (CDCl3): δ
199.8 (C), 144.9 (C), 143.9 (C), 137.8 (CH), 134.0 (CH), 129.0
(CH), 129.1 (CH2), 127.7 (CH), 44.1 (CH2), 18.4 (CH2), 14.3
(CH3), 13.2 (CH3), -3.1 (CH3). M. S. m/z 272 (M+, 5), 257 (M+
- CH3, 100), 195 (M+ - Ph, 67), 135 (SiMe2Ph, 37). Anal. Calcd
for C17H24OSi: C, 74.94; H, 8.88. Found: C, 75.28; H, 9.17.
(k) 2-Methyl-1-cyclopentenyl 2-(Dimethylphenylsilyl)-
2-methyl-2-propenyl Ketone (8f). Colorless oil. IR (neat; ν,
cm-1): 1655, 1600, 1240, 1090. 1H NMR (CDCl3): δ 7.54-7.27
(5H, m), 5.67 (1H, d, J ) 2.4 Hz), 5.58 (1H, d, J ) 2.4 Hz),
3.27 (2H, s), 2.55-2.50 (2H, m), 2.48-2.39 (2H, m), 2.00 (3H,
s), 1.76 (2H, quint, J ) 7.5 Hz), 0.39 (6H, s). 13C NMR
(CDCl3): δ 199.1 (C), 154.6 (C), 144.1 (C), 137.6 (C), 135.1 (C),
134.0 (CH), 129.4 (CH2), 129.0 (CH), 127.7 (CH), 49.0 (CH2),
40.7 (CH2), 33.9 (CH2), 21.5 (CH2), 16.7 (CH3), -3.1 (CH3).
MS: m/z 269 (M+ - CH3, 23), 207 (M+ - Ph, 19), 135 (SiMe2-
Ph, 22). EI HRMS. Calcd for C18H24OSi (M+): 284.1596.
Found: 284.1605.
(a) 2-(Dimethylphenylsilyl)-5-methylhexa-1,5-dien-4-
one (8b). Colorless oil. IR (neat, cm-1): 1687, 1635, 1105. 1H
NMR (CDCl3): δ 7.67-7.38 (5H, m), 5.85 (1H, s), 5.78 (1H, s),
5.74 (1H, d, J ) 2.0 Hz), 5.68 (1H, d, J ) 2.0 Hz), 3.55 (2H, s),
1.89 (3H, s), 0.47, 0.46 (3H, s). 13C NMR (CDCl3): δ 200.6 (C),
144.7 (C), 144.2 (C), 137.5 (Cd), 134.1 (CH), 129.7 (CH), 129.2
(CH2), 127.8 (CH), 125.2 (CH2), 44.7 (CH2), 17.7 (CH3), -2.9
(CH3). MS: m/z 229 (M+ - CH3, 100), 135 (SiMe2Ph, 28). Anal.
Calcd for C15H20OSi: C, 73.71; H, 8.25. Found: C, 73.98; H,
8.59.
(b) 5-Chloro-2-(dimethylphenylsilyl)hexa-1,5-dien-4-
one (8c). Colorless oil. IR (neat, cm-1): 1692, 1633, 1105. 1H
NMR (CDCl3): δ 7.64-7.27 (5H, m), 6.17 (1H, d, J ) 2 Hz),
5.96 (1H, d, J ) 2 Hz), 5.72 (1H, s), 5.65 (1H, s), 3.53 (2H, s),
0.47 (6H, s). 13C NMR (CDCl3): δ 192.9 (C), 143.3 (C), 138.9
(C), 138.0 (C), 134.1 (CH), 130.2 (CH2), 129.2 (CH), 127.8 (CH),
124.2 (CH2), 44.9 (CH2), -2.4 (CH3), -3.2 (CH3). MS: m/z 264
(M+, 9), 229 (M+ - Cl, 20), 135 (SiMe2Ph, 35). Anal. Calcd for
C14H17ClOSi: C, 63.50; H, 6.47. Found: C, 63.88; H, 8.72.
Silylcupration of Allene with r,â-Unsaturated Imines.
BF3‚Et2O (6 mmol) was added at -60 °C to the solution
previously prepared, and the mixture stirred for an additional
period of 10 min. The imine (6 mmol) in THF was slowly
dropped in at -60 °C and stirred at this temperature for 1 h.
The reaction mixture was left to warm to 0 °C, quenched with
basic saturated ammonium chloride solution, and extracted
with ether. The organic layer was dried (MgSO4), evaporated,
and chromatographed to give the products 10a-d.
(a) 4-[(Dimethylphenylsilyl)methyl]pent-4-enal (10a).
Colorless oil. IR (neat, cm-1): 1725, 1635, 1249, 1113. 1H NMR
(CDCl3): δ 9.66 (1H, t, J ) 1.8 Hz), 7.56-7.38 (5H, m), 4.62
(2H, s), 2.50 (2H, td, J ) 7.3 and 1.8 Hz), 2.19 (2H, t, J ) 7.3
Hz), 1.81 (2H, s), 0.37 (3H, s), 0.36 (3H, s). 13C NMR (CDCl3):
δ 202.1 (C), 145.0 (C), 138.6 (C), 133.6 (C), 129.1 (C), 127.8
(C), 108.3 (CH2), 41.7 (CH2), 30.2 (CH2), 26.3 (CH2), -3.0 (CH3).
MS: m/z 203 (M+ - CHO, 10), 135 (SiMe2Ph, 100). Anal. Calcd
for C14H20OSi: C, 72.36; H, 8.67. Found: C, 72.68; H, 8.91.
(l) 1-Cyclohexenyl 2-(Dimethylphenylsilyl)-2-propenyl
Ketone (8 g). Colorless oil. IR (neat, cm-1): 1695, 1630, 1240,
1090. 1H NMR (CDCl3): δ 7.54-7.27 (5H, m), 6.66 (1H, s), 5.68
(1H, d, J ) 2.2 Hz), 5.57 (1H, d, J ) 2.2 Hz), 3.40 (2H, s),
2.14-2.10 (2H, m), 2.14-2.10 (2H, m), 1.57-1.55 (4H, m), 0.39
(6H, s). 13C NMR (CDCl3): δ 199.9 (C), 144.9 (C), 140.6 (CH),
138.8 (C), 137.6 (C), 134.0 (CH), 129.3 (CH2), 129.0 (CH), 127.7
(CH), 44.1 (CH2), 26.0 (CH2), 23.0 (CH2), 21.8 (CH2), 21.4 (CH2),
-3.1 (CH3). MS: m/z 284 (M+, 5), 269 (M+ - CH3, 15), 207
(M+ - Ph, 18), 135 (SiMe2Ph, 45). Anal. Calcd for C18H24OSi:
C, 76.00; H, 8.50. Found: C, 76.38; H, 8.79.
(m) 1-Cycloheptenyl 2-(Dimethylphenylsilyl)-2-pro-
penyl Ketone (8h). Colorless oil. IR (neat, cm-1): 1650, 1240,
1090. 1H NMR (CDCl3): δ 7.55-7.27 (5H, m), 6.83 (1H, t, J )
6.7 Hz), 5.68 (1H, d, J ) 2.2 Hz), 5.57 (1H, d, J ) 2.2 Hz),
3.42 (2H, s), 2.44-2.40 (2H, m), 2.27-2.21 (2H, m), 1.78-1.72
(2H, m), 1.56-1.47 (2H, m), 1.46-1.37 (2H, m), 0.40 (6H, s).
13C NMR (CDCl3): δ 199.9 (C), 145.7 (C), 145.2 (CH), 145.1
(C), 137.6 (C), 134.0 (CH), 129.1 (CH2), 129.0 (CH), 127.7 (CH),
44.1 (CH2), 32.2 (CH2), 29.0 (CH2), 26.0 (CH2), 25.7 (CH2), 25.5
(CH2), -3.1 (CH3). MS: m/z 299 (M+ + 1, 5), 283 (M+ - CH3,
39), 221 (M+ - Ph, 30), 135 (SiMe2Ph, 28). Anal. Calcd for
C19H26OSi: C, 76.45; H, 8.78. Found: C, 76.78; H, 9.07.
(n) 2-(Dimethylphenylsilyl)octa-1,5-dien-4-one (8i). Col-
1
orless oil. IR (neat, cm-1): 1660, 1620, 1240, 1110. H NMR
(CDCl3: δ 7.55-7.27 (5H, m), 6.78-6.68 (1H, dt, J ) 15.8 and
6.3 Hz), 6.01 (1H, dt, J ) 15.8 and 1.6 Hz), 5.75 (1H, d, J )
2.2 Hz), 5.62 (1H, d, J ) 2.2 Hz), 3.30 (2H, s), 2.19-2.14 (2H,
m), 1.03 (3H, t, J ) 7.5 Hz), 0.40 (6H, s). 13C NMR (CDCl3): δ
198.8 (C), 149.1 (CH), 143.9 (C), 137.4 (C), 134.0 (CH), 130.1
(CH2), 129.1 (CH), 128.6 (CH), 127.7 (CH), 47.3 (CH2), 25.4
(CH2), 12.1 (CH3), -3.2 (2×CH3). MS: m/z 243 (M+ - CH3,
30), 181 (M+ - Ph, 35), 135 (SiMe2Ph, 70). Anal. Calcd for
C16H22OSi: C, 74.36; H, 8.58. Found: C, 74.68; H, 8.86.
(o) 1-Cyclopentenyl 2-(Dimethylphenylsilyl)-2-pro-
penyl Ketone (8j). Colorless oil. IR (neat, cm-1): 1700, 1645,
1240, 1090. 1H NMR (CDCl3): δ 7.53-7.26 (5H, m), 6.49 (1H,
s), 5.71 (1H, d, J ) 2.4 Hz), 5.57 (1H, d, J ) 2.4 Hz), 3.42 (2H,
s), 2.49-2.40 (4H, m), 1.85 (2H, quint, J ) 7.6 Hz), 0.38 (6H,
s). 13C NMR (CDCl3): δ 197.3 (C), 145.3 (C), 144.4 (C), 144.0
(CH), 137.4 (C), 134.0 (CH), 129.6 (CH2), 129.0 (CH), 127.7
(CH), 46.1 (CH2), 33.9 (CH2), 30.5 (CH2), 22.7 (CH2), -3.1
(CH3). MS: m/z 255 (M+ - CH3, 44), 193 (M+ - Ph, 41), 135
(SiMe2Ph, 100). Anal. Calcd for C17H22OSi: C, 75.50; H, 8.20.
Found: C, 75.93; H, 8.51.
(b) 4-[(Dimethylphenylsilyl)methyl]-3-methylpent-4-
enal (10b). Colorless oil. IR (neat, cm-1): 1725, 1633, 1249,
1113. 1H NMR (CDCl3): δ 9.54 (1H, t, J ) 2.3 Hz), 7.56-7.37
(5H, m), 4.68 (1H, s), 4.65 (1H, s), 2.48 (1H, dd, J ) 15.3 and
5.2 Hz), 2.45-2.34 (1H, m), 2.27 (1H, ddd, J ) 15.3, 7.4 and
2.3 Hz), 1.82 (2H, s), 1.05 (3H, d, J ) 6.6 Hz), 0.38 (6H, s). 13
C
NMR (CDCl3): δ 202.3 (C), 150.1 (C), 138.6 (C), 133.6 (CH),
129.1 (CH), 127.8 (CH), 107.3 (CH2), 49.3 (CH2), 35.2 (CH),
J. Org. Chem, Vol. 70, No. 17, 2005 6881

Barbero et al.
25.0 (CH2), 19.7 (CH3), -3.0 (CH3). MS: m/z 231 (M+ - CH3,
5), 217 (M+ - COH, 10), 135 (SiMe2Ph, 100). Anal. Calcd for
C15H22OSi: C, 73.11; H, 9.00. Found: C, 73.41; H, 9.31.
(c) 4-[(Dimethylphenylsilyl)methyl]-3-propylpent-4-
enal (10c). Colorless oil. IR (neat, cm-1): 1715, 1630, 1245,
1110. 1H NMR (CDCl3): δ 9.48 (1H, t, J ) 2.1 Hz), 7.58-7.27
(5H, m), 4.70 (1H, s), 4.66 (1H, s), 2.43-2.27 (3H, m), 1.77 (2H,
s), 1.57-1.13 (4H, m), 0.86 (3H, t, J ) 7.1 Hz), 0.37 (3H, s),
0.36 (3H, s). 13C NMR (CDCl3): δ 202.7 (C), 148.2 (C), 138.7
(C), 133.7 (CH), 129.1 (CH), 127.8 (CH), 109.0 (CH2), 47.3
(CH2), 40.8 (CH), 35.9 (CH2), 24.4 (CH2), 20.2 (CH2), 14.1 (CH3),
-2.6 (CH3), -2.8 (CH3). MS: m/z 274 (M+, 3), 259 (M+ - CH3,
5), 245 (M+ - CHO, 7), 139 (M+ - SiMe2Ph, 10), 135 (SiMe2-
Ph, 100). Anal. Calcd for C17H26OSi: C, 74.39; H, 9.55.
Found: C, 74.68; H, 9.86.
Sı´ntesis of Methylenecycloheptanones. To a stirred
solution of enones 12a-d (3 mmol) in dry toluene (15 mL) is
added EtAlCl2 (1.8 M, 3 mmol) at 0 °C under nitrogen. The
mixture is stirred at this temperature for 1 h, and then
saturated solution of NaHCO3 (2 mL) is added. Extraction
(Et2O), drying (MgSO4), and chromatography gave the follow-
ing compounds.
(a) 4-Methylenecycloheptanone (13a). Colorless oil. IR
(neat, cm-1): 1730, 1630. 1H NMR (CDCl3): δ 4.82 (1H, s),
4.78 (1H, s), 2.58 (2H, t, J ) 6.2 Hz), 2.52 (2H, t, J ) 6.5 Hz),
2.33-2.45 (4H, m), 1.83-1.73 (2H, m). 13C NMR (CDCl3): δ
215.1 (CdO), 139.5 (C), 112.6 (CH2), 43.3 (CH2), 43.1 (CH2),
38.2 (CH2), 31.8 (CH2), 24.2 (CH2). MS: m/z 124 (M+, 19). Anal.
Calcd for C8H12O: C, 77.38; H, 9.74. Found: C, 77.72; H, 9.99.
(b) 3-Methyl-4-methylenecycloheptanone (13b). Color-
less oil. IR (neat, cm-1): 1735, 1650. 1H NMR (CDCl3): δ 4.81
(1H, s), 4.78 (1H, s), 2.49-2.21 (5H, m), 2.01-1.80 (4H, m),
1.30 (3H, d, J ) 7.4 Hz). 13C NMR (CDCl3): δ 212.7 (CdO),
145.0 (C), 111.1 (CH2), 49.8 (CH), 43.8 (CH2), 41.2 (CH2), 39.8
(CH2), 26.4 (CH2), 20.8 (CH3). MS: m/z 138 (M+, 12), 123 (M+
- CH3, 10). Anal. Calcd for C9H14O: C, 78.21; H, 10.21.
Found: C, 78.59; H, 10.48.
(c) 4-Methylene-3-propylcycloheptanone (13c). Color-
less oil. IR (neat, cm-1): 1728, 1632. 1H NMR (CDCl3): δ 4.83
(1H, s), 4.77 (1H, s), 2.55-2.20 (5H, m), 1.70-1.50 (4H, m),
1.39-1.21 (4H, m), 0.90 (3H, t, J ) 7.0 Hz). 13C NMR
(CDCl3): δ 213.9 (CdO), 139.1 (C), 111.9 (CH2), 51.9 (CH2),
48.9 (CH2), 43.3 (CH), 35.8 (CH2), 35.4 (CH2), 24.9 (CH2), 20.4
(CH2), 13.4 (CH3). MS: m/z 166 (M+, 20). Anal. Calcd for
C11H18O: C, 79.46; H, 10.91. Found: C, 79.81; H, 11.21.
(d) 4-Methylene-3-phenylcycloheptanone (13d). Color-
less oil. IR (neat, cm-1): 1730, 1630. 1H NMR (CDCl3): δ 7.53-
7.27 (5H, m), 4.88 (1H, s), 4.85 (1H, s), 3.83 (1H, dd, J ) 7.9
and 7.7 Hz), 2.98 (1H, dd, J ) 16.2 and 7.9 Hz), 2. 83 (1H, dd,
J ) 16.2 and 7.7 Hz), 2.66-2.48 (4H, m), 1.71-1.56 (2H, m).
13C NMR (CDCl3): δ 208.0 (CdO), 147.1 (C), 142.2 (C), 129.0
(CH), 127.6 (CH), 126.1 (CH), 110.2 (CH2), 49.7 (CH2), 47.5
(CH), 43.1 (CH2), 29.6 (CH2), 21.9 (CH2). MS: m/z 200 (M+,
20), 77 (Ph, 14). Anal. Calcd for C14H16O: C, 83.96; H, 8.05.
Found: C, 84.29; H, 8.38.
135 (SiMe2Ph, 100). Anal. Calcd for C17H24OSi: C, 74.94; H,
8.88. Found: C, 75.28; H, 9.21.
(b) [1R*,2R*]-2-Methyl-4-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (14b). Colorless
oil. IR (neat, cm-1): 3400, 1650, 1240, 1090. 1H NMR
(CDCl3): δ 7.59-7.37 (5H, m), 5.92 (1H, d, J ) 2.9 Hz), 5.71
(1H, d, J ) 2.9 Hz), 4.84-4.82 (2H, m), 2.74-2.67 (1H, m),
2.43 (1H, d, J ) 14.1 Hz), 2.43 (1H, d, J ) 14.1 Hz), 2.30 (1H,
d, J ) 14.1 Hz), 2.07-1.89 (3H, m), 1.33-1.29 (1H, s, OH),
0.87 (3H, d, J ) 7.0 Hz), 0.45 (3H, s), 0.43 (3H, s). 13C NMR
(CDCl3): δ 148.6 (C), 147.1 (C), 138.3 (C), 133.9 (CH), 131.3
(CH2), 129.1 (CH), 127.9 (CH), 107.2 (CH2), 82.0 (C), 44.3 (CH2),
44.2 (CH), 41.2 (CH2), 38.7 (CH2), 15.8 (CH3), -2.2 (CH3), -2.5
(CH3). MS: m/z 271 (M+ - CH3, 7), 151 (M+ - SiMe2Ph, 12),
135 (SiMe2Ph, 100). Anal. Calcd for C18H26OSi: C, 75.46; H,
9.15. Found: C, 75.78; H, 9.36.
(c) [1R*,2S*]-2-Methyl-4-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (15b). Colorless
oil. IR (neat, cm-1): 3400, 1650, 1240, 1090. 1H NMR
(CDCl3): δ 7.59-7.37 (5H, m), 5.92 (1H, d, J ) 2.9 Hz), 5.68
(1H, d, J ) 2.9 Hz), 4.85 (1H, s with fine couplings), 4.81 (1H,
s with fine couplings), 2.61 (1H, d, J ) 13.7 Hz), 2.45 (1H, dd,
J ) 16.4 and 8.1 Hz ), 2.25 (1H, ddd, J ) 16.4, 4, 9 and 2.3
Hz), 2.15 (1H, d, J ) 13.7 Hz), 2.14-2.10 (2H, m), 1.90-1.80
(1H, m), 1.06 (1H, s, OH), 0.90 (3H, d, J ) 6.7 Hz), 0.43 (6H,
s). 13C NMR (CDCl3): δ 148.9 (C), 147.4 (C), 138.4 (C), 134.0
(CH), 131.0 (CH2), 129.1 (CH), 127.9 (CH), 106.6 (CH2), 81.0
(C), 46.7 (CH2), 44.8 (CH2), 43.0 (CH), 38.7 (CH2), 12.4 (CH3),
-2.2 (CH3), -2.3 (CH3). MS: m/z 271 (M+ - CH3, 7), 151 (M+
- SiMe2Ph, 12), 135 (SiMe2Ph, 100).
(d) [1R*,4S*]-4-Methyl-3-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (14d) and [1R*,-
4R*] (15d). Colorless oils. Chromatography gave the alcohols
as a mixture. (14d) IR (neat, cm-1): 3560, 1650, 1240, 1090.
1H NMR (CDCl3): δ 7.56-7.27 (5H, m), 5.92-5.89 (1H, m),
5.71-5.69 (1H, m), 4.85-4.78 (2H, m), 2.72-2.67 (1H, m), 2.45
(1H, d, J ) 10.6 Hz), 2.49-2.19 (3H, m), 1.77 (1H, ddd, J )
12.9, 7.4 and 2.4 Hz), 1.33-1.15 (2H, m), 1.04 (3H, d, J ) 6.7
Hz), 0.43 (6H, s). 13C NMR (CDCl3): δ 155.5 (C), 147.2 (C),
138.2 (C), 133.9 (CH), 131.3 (CH2), 129.1 (CH), 127.9 (CH),
105.4 (CH2), 79.3 (C), 47.6 (CH2), 47.2 (CH2), 46.6 (CH2), 36.3
(CH), 20.2 (CH3), -2.3 (CH3), -2.4 (CH3). MS: m/z 286 (M+,
16), 271 (M+ - CH3, 97), 194 (M+ - Ph - CH3, 19), 135 (SiMe2-
1
Ph, 29). (15d) H NMR (CDCl3): δ 7.56-7.27 (5H, m), 5.92-
5.89 (1H, m), 5.71-5.69 (1H, m), 4.85-4.78 (2H, m), 2.45 (2H,
d, J ) 10.6 Hz), 2.49-2.19 (4H, m), 1.98 (1H, dd, J ) 13.0 and
8.9 Hz), 1.33-1.15 (2H, m), 1.09 (3H, d, J ) 6.8 Hz), 0.43 (6H,
s). 13C NMR (CDCl3): δ 155.5 (C), 147.1 (C), 138.2 (C), 133.9
(CH), 131.5 (CH2), 129.1 (CH), 127.9 (CH), 105.4 (CH2), 79.2
(C), 48.7 (CH2), 47.5 (CH2), 47.1 (CH2), 36.3 (CH), 18.6 (CH3),
-2.5 (CH3).
(e)
[1R*,4S*]-4-Ethyl-3-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (14i) and [1R*,-
4R*] (15i). Colorless oils. Chromatography gave the alcohols
as a mixture. (14i) IR (neat, cm-1): 3560, 1650, 1240, 1090.
1H NMR (CDCl3): δ 7.59-7.27 (5H, m), 5.91-5.88 (1H, m),
5.72-5.67 (1H, m), 4.85 (1H, s with fine couplings), 4.80 (1H,
s with fine couplings), 2.49-2.15 (3H, m), 2.41 (2H, s), 1.92
(1H, ddd, J ) 13.2, 8.8 and 1.2 Hz), 1.71-1.55 (2H, m), 1.33-
1.15 (2H, m), 0.86 (3H, t, J ) 7.4 Hz), 0.43 (3H, s), 0.42 (3H,
s). 13C NMR (CDCl3): δ 154.0 (C), 147.0 (C), 138.2 (C), 133.9
(CH), 131.6 (CH2), 129.1 (CH), 127.9 (CH), 106.1 (CH2), 78.9
(C), 47.7 (CH2), 46.5 (CH2), 44.4 (CH2), 43.4 (CH), 28.1 (CH2),
12.1 (CH3), -2.4 (CH3), -2.5 (CH3). M. S. m/z 285 (M+-CH3,
5), 165 (M+-SiMe2Ph, 7), 135 (SiMe2Ph, 100). (15i): 1H NMR
(CDCl3): δ 7.59-7.27 (5H, m), 5.91-5.88 (1H, m), 5.72-5.67
(1H, m), 4.85 (1H, s with fine couplings), 4.80 (1H, s with fine
couplings), 2.49-2.15 (3H, m), 2.41 (2H, s), 1.79 (1H, ddd, J
) 13.0, 7.7 and 2.6 Hz), 1.71-1.55 (2H, m), 1.33-1.15 (2H,
m), 0.85 (3H, t, J ) 7.3 Hz), 0.43 (3H, s), 0.42 (3H, s). 13C NMR
(CDCl3): δ 154.3 (C), 147.2 (C), 138.2 (C), 133.9 (CH), 131.3
(CH2), 129.1 (CH), 127.7 (CH), 106.0 (CH2), 79.3 (C), 47.4 (CH2),
Allylsilane-Terminated Cyclizations. EtAlCl2 (2 mmol,
1.8 M) was added slowly to a solution of 7 (2 mmol) in DCM
(8 mL), under nitrogen. After stirring at 0 °C for 0.5 h, brine
was added (5 mL) and the mixture extracted with ether, dried,
and evaporated. Purification by flash chromatography gave the
products 14 and 15.
(a) 1-[2-(Dimethylphenylsilyl)-2-propenyl]-3-methyl-
enecyclopentan-1-ol (14a). Colorless oil. IR (neat, cm-1):
1
3585, 1665, 1550, 1240, 1090. H NMR (CDCl3): δ 7.57-7.27
(5H, m), 5.91 (1H, d, J ) 2.2 Hz), 5.70 (1H, d, J ) 2.2 Hz),
4.89-4.80 (2H, m), 2.51-2.39 (1H, m), 2.46 (2H, s), 2.36-2.22
(1H, m), 2.29 (1H, d, J ) 16.6 Hz), 2.15 (1H, d, J ) 16.6 Hz),
1.65-1.57 (2H, m), 1.22 (1H, s), 0.43 (6H, s). 13C NMR
(CDCl3): δ 150.4 (C), 147.1 (C), 138.2 (C), 133.9 (CH), 131.4
(CH2), 129.0 (CH), 127.7 (CH), 106.8 (CH2), 80.9 (C), 47.0 (CH2),
46.4 (CH2), 39.3 (CH2), 30.2 (CH2), -2.4 (CH3). MS: m/z 257
(M+ - CH3, 7), 195 (M+ - Ph, 30), 137 (M+ - SiMe2Ph, 68),
6882 J. Org. Chem., Vol. 70, No. 17, 2005

Silylcupration of Allenes with Nitriles and Imines
46.9 (CH2), 45.8 (CH2), 43.1 (CH), 27.2 (CH2), 11.8 (CH3), -2.4
(CH3), -2.5 (CH3).
5), 135 (SiMe2Ph, 100). Anal. Calcd for C23H28OSi: C, 79.26;
H, 8.10. Found: C, 79.58; H, 8.44.
(f) [1R*,4S*]-1-[2-(Dimethylphenylsilyl)-2-propenyl]-3-
methylene-4-phenylcyclopentan-1-ol (14k). Colorless oil.
IR (neat, cm-1) 3540, 1650, 1240, 1090. 1H NMR (CDCl3) δ
7.57-7.14 (10H, m), 5.94 (1H, d, J ) 2.9 Hz), 5.73 (1H, d, J )
2.9 Hz), 4.93 (1H, d, J ) 2.1 Hz), 4.49 (1H, d, J ) 2.1 Hz),
3.59 (1H, dd, J ) 9.4 and 8.7 Hz), 2.54 (1H, d, J ) 15.4 Hz),
2.52 (2H, s), 2.40 (1H, d, J ) 15.4 Hz), 2.26 (1H, dd, J ) 13.3
and 9.4 Hz), 1.81 (1H, dd, J ) 13.3 and 8.7 Hz), 1.45 (1H, s,
OH), 0.45 (3H, s), 0.43 (3H, s). 13C NMR (CDCl3) δ 153.9 (C),
144.5 (C), 138.1 (C), 134.0 (CH), 131.7 (CH2), 129.3 (CH), 129.1
(CH), 128.2 (CH), 128.0 (CH), 127.7 (CH), 126.0 (CH), 109.1
(CH), 106.0 (CH2), 78.9 (C), 48.6 (CH), 48.2 (CH2), 46.5 (CH2),
29.6 (CH2), -2.4 (CH3), -2.5 (CH3). MS: m/z 271 (M+ - Ph,
Acknowledgment. We thank the Ministry of Sci-
ence and Technology of Spain (Grant BQU2003-03035)
and the “Junta de Castilla y Leo´n” (Grant VA050/2004)
for finantial support. We thank Prof. D. Miguel (UVA)
for X-ray crystallographic help.
Supporting Information Available: General experimen-
tal methods, details of synthesis as well as spectra of com-
pounds 11a-d and 12a-d, and crystallographic data collection
parameters for compound 11d. This material is available free
of charge via the Internet at http://pubs.acs.org.
JO0509814
J. Org. Chem, Vol. 70, No. 17, 2005 6883