Palladium-catalyzed and samarium-promoted coupling of stereochemically-biased allylic acetates with carbonyl compounds

Article abstract of DOI:10.1016/j.tet.2009.10.104

Stereochemically-biased bicyclic allylic acetates endo- and exo-1 were shown as being allyl donors for Pd-catalyzed carbonyl allylation using stoichiometric quantities of samarium diodide. Cyclopentenyl acetate and bicyclic derivatives 1 react with cyclic ketones in the presence of SmI₂ without requirement of palladium catalysis. Use of enantiomerically enriched substrate suggests that the reaction goes through a π-allyl samarium complex. However, this reactivity appears to be restricted to strained cyclopentenyl acetates since other linear and cyclic allylic acetates do not give the carbonyl allylation product.

Full text of DOI:10.1016/j.tet.2009.10.104

Tetrahedron 66 (2010) 222–226
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Palladium-catalyzed and samarium-promoted coupling
of stereochemically-biased allylic acetates with carbonyl compounds
Olivier Jacquet, Timm Bergholz, Caroline Magnier-Bouvier, Mohamed Mellah,
*
´
Regis Guillot, Jean-Claude Fiaud
´
´
ˆ
´
Institut de Chimie Moleculaire et des Materiaux d’Orsay, CNRS UMR 8182, ICMMO, bat 420, Universite Paris-Sud, 91405 Orsay, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Stereochemically-biased bicyclic allylic acetates endo- and exo-1 were shown as being allyl donors for Pd-
catalyzed carbonyl allylation using stoichiometric quantities of samarium diodide. Cyclopentenyl acetate
and bicyclic derivatives 1 react with cyclic ketones in the presence of SmI2 without requirement of
palladium catalysis. Use of enantiomerically enriched substrate suggests that the reaction goes through
Received 25 September 2009
Received in revised form 23 October 2009
Accepted 29 October 2009
Available online 4 November 2009
a
p-allyl samarium complex. However, this reactivity appears to be restricted to strained cyclopentenyl
acetates since other linear and cyclic allylic acetates do not give the carbonyl allylation product.
Keywords:
Palladium
Ó 2009 Elsevier Ltd. All rights reserved.
Homogeneous catalysis
Samarium
Coupling
Ketone allylation
1. Introduction
has been postulated for the SmI2-mediated reduction of allylic ac-
etates5 and synthesis of allylsilanes.6 Since no enantioselective
Allylation of carbonyl compoundsdincluding its enantiose-
lective versiondis recognized as an important and useful carbon–
carbon bond formation process.1 It requires the use of nucleophilic
reagents such as allylmetals that are more often prepared from the
corresponding allylic halides.
version of such a reaction has been carried out, we aimed at in-
vestigating the SmI2-mediated, Pd-catalyzed allylation of ketones
in order to get some insight into the mechanism and stereochem-
ical outcome of this reaction.
More friendly allylic alcohol derivatives (acetate, alkyl carbon-
ate, phosphate) or allylic alcohols themselves could be used as
allylation reagents when activated with palladium(0) catalysts as
2. Results and discussion
Diastereomeric stereochemically-biased allylic acetates endo-1
and exo-1 have been shown to be useful for gathering information
about the mechanism and stereochemical outcome of Pd-catalyzed
allylation of nucleophiles performed with allylic acetates.7 exo-1
was unreactive with either ‘‘soft’’ or ‘‘hard’’ nucleophiles in the
presence of palladium(0)/phosphine complexes, whereas only
‘‘hard’’ nucleophiles underwent reaction with endo-1 under the
same conditions. We anticipated that these model substrates could
give information about the mechanistic features of the SmI2-in-
duced umpolung of allylpalladium complexes.
As expected, endo-acetate 1 reacted with cyclobutanone and
cyclohexanone in a Pd(0)-catalyzed, SmI2-mediated Barbier-type
process to give the homoallylic alcohols 2a and 2b, in poor isolated
yields however, 48% and 38%, respectively. A single-crystal X-ray
diffractometry structure of 2b could be obtained (Scheme 1, Fig. 1).
Surprisingly, reactions of the diastereomeric exo-acetate 1 per-
formed under identical conditions (THF, room temperature, 20 h)
p
-allylpalladium complexes, after these latter being made nucleo-
philic through an umpolung process. The charge reversal of the
allylic moiety can be made by electrochemical means, by reduction
with a metal (Zn), a salt (SnCl2, SmI2), or by transmetalation with an
organometal (alkylborane, alkylzinc, allylsilane).2
Among these umpolung processes, samarium diodide was used
for Pd(0) catalyzed allylation of carbonyl compounds with allylic
acetates.3 Allylic carbonates and phosphates were also investigated
as substrates with ketones through mischmetal/SmI2/Pd(0)cat me-
diating system.4 In both reports, the allylic substrates were shown
to react preferentially at the least substituted allylic terminus. The
mechanism is supposed to involve the reduction of the in-
termediate
p-allylpalladium complex by SmI2. Such a mechanism
* Corresponding author. Tel.: þ33 1 69 15 78 19; fax: þ33 1 69 15 46 80.
E-mail address: fiaud@icmo.u-psud.fr (J.-C. Fiaud).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.10.104

O. Jacquet et al. / Tetrahedron 66 (2010) 222–226
223
O
[Pd(PPh3)4 (2 mol%)
+
SmI2 (2.2 equiv), THF, rt, 20 h
n
OH
n
H
AcO
( )-endo-1
H
slow reaction
( )-2a n = 1, 48%
( )-2b n = 3, 38%
Scheme 1. Pd-catalyzed, samarium-promoted allylation of cyclic ketone by stereochemically-biased allylic acetate endo-1.
homoallylic alcohol 2b in nearly as good a yield (60%) as the one
(70%) recorded under palladium catalysis (vide supra).
In both cases, the reduction product 3 was isolated as a side
product in low yield, likely resulting from a radical-induced pro-
tonation by the THF solvent (Scheme 4).
This behavior was confirmed by reaction of cyclopentenyl ace-
tate with cyclohexanone in the presence of 2.2 equiv SmI2, which
gave the homoallylic alcohol 4 in yields of 52% (without Pd catalyst)
and 70% (with Pd) (Scheme 5).
In order to get some insight into the mechanism of the reaction,
we aimed at looking further the stereochemistry of the reaction
using an enantiomerically enriched allylic substrate. Since we were
not able to resolve analytically the enantiomers of 2b, (by chiral
HPLC, even after derivatization of the alcohol into the corre-
sponding acetate or benzyl carbamate), reactions were performed
with 4-phenylcyclohexanone as the substrate instead of cyclo-
hexanone. Two diastereomers 5 were obtained in a 3/1 ratio. The
major diastereomer 5a could be separated by silica gel chroma-
tography from the minor 5b and enantiomers of 5a distinguished
by chiral HPLC. The relative stereochemistry of 5a could not be
established. When enantiomerically enriched exo-1 was reacted
with 4-phenylcyclohexanone in the presence of 2.2 equiv SmI2,
two diastereomers 5 were obtained in a 3/1 ratio, and the homo-
Figure 1. ORTEP drawing of the X-ray crystallographic structure of 2b with the atom
labeling scheme. Ellipsoids are drawn at the 30% probability level.
with cyclobutanone and cyclohexanone gave, through quantitative
conversion, the same products 2a and 2b, and in higher yields (57%
and 70%, respectively) (Scheme 2).
O
[Pd(PPh3)4 (2 mol%)
SmI2 (2.2 equiv), THF, rt, 20 h
+
n
H
OAc
OH
n
H
100% conversion
( )-exo-1
( )-2a n = 1, 57%
( )-2b n = 3, 70%
Scheme 2. Pd-catalyzed, samarium-promoted allylation of cyclic ketone by stereochemically-biased allylic acetate exo-1.
We were then inquiring about any involvement of the palladium
allylic alcohol 5a was obtained in good yield but in racemic form
(Scheme 6).
These results indicate that a symmetrical
-allyl samarium species might be involved at some stage of
the process, through one or two consecutive one-electron
transfer.
complex to promote the reaction, especially for diastereomer exo-1.
Reactions were then performed in the absence of any palladium
complex. endo-1 acetate exposed to samarium diodide afforded the
product 2b on reaction with cyclohexanone but in low (12%) con-
version (vs 38% in the presence of Pd catalyst) (Scheme 3).
p
-allyl radical or
a
p
Conversely, reaction of exo-acetate 1 with cyclohexanone under
Barbier-like conditions proceeded smoothly to provide the
When the reaction of exo-1 was performed in the presence of
1 equiv of O-deuterated ethanol and SmI2 (2 equiv), the deuterated
O
SmI2 (2.2 equiv), THF, rt, 20 h
12% conversion
+
+
OH
H
AcO
( )-endo-1
H
3
2b
Scheme 3. Samarium-promoted allylation of cyclic ketone by stereochemically-biased allylic acetate endo-1.

224
O. Jacquet et al. / Tetrahedron 66 (2010) 222–226
O
SmI2 (2.2 equiv), THF, rt, 20 h
100% conversion
+
+
OH
H
H
OAc
3
( )-exo-1
( )-2b 60% yield
Scheme 4. Samarium-promoted allylation of cyclic ketone by stereochemically-biased allylic acetate exo-1.
results are better explained by the formation of an allylsamarium
intermediate compound resulting of a 2-electron transfer process
onto the allylic acetate.
In order to investigate the generalization of the reactivity of
samarium-induced coupling of allylic acetates with cyclohexanone
under Barbier conditions, we carried out reactions with allyl, cin-
namyl, cyclohex-2-enyl, and cyclohept-2-enyl acetates under the
O
SmI2 (2.2 equiv), THF, rt, 20 h
100% conversion
+
OAc
OH
4
Scheme 5. Samarium-promoted allylation of cyclic ketone by cyclopentenyl acetate.
O
SmI2 (2.2 equiv), THF, rt, 20 h
quant. conversion
+
OH
H
H
OAc
Ph
(-)-exo-1 (66% ee)
Ph
( )-5a 56% yield
Scheme 6. Samarium-promoted allylation of 4-phenylcyclohexanones by stereochemically-biased allylic acetate (ꢀ)-exo-1.
reduction compound was obtained (2H NMR and mass spectrom-
etry), in agreement with the formation of an intermediate allylsa-
marium species (Scheme 7).
same conditions used above for reaction of cyclopent-2-enyl acetate
and bicyclic allylic acetates endo-1 and exo-1. Surprisingly, allylation
of cyclohexanone did not take place. Moreover, a competitive re-
action between equimolecular amounts of cyclopent-2-enyl and
cyclohex-2-enyl acetates with cyclohexanone in the presence of
4.4 equiv of diodosamarium in THF resulted (GLC and 1H NMR
monitorings) in full conversion of only cyclopent-2-enyl acetate
into the homoallylic product 4. Our results are in agreement with
those early reported by Inanaga for the reduction of allylic acetates
with samarium diodide under Pd catalysis since he mentioned that
no reaction occurred in the absence of Pd(0).5 However, he did not
investigate the reaction of cyclopentenyl acetate or analogs.
SmI2 (2.2 equiv)
EtOD (1 equiv)
H
OAc
THF, rt
H
D
( )-exo-1
Scheme 7. Samarium-promoted reduction of stereochemically-biased allylic acetate
exo-1.
To show the difference in behavior of strained and unstrained
acetates would arise from a difference in reduction potential, we
measured the reduction potential of various allylic substrates by cy-
clic voltammetry to reveal that i) there was no significative difference
(ꢀ0.92 to ꢀ1.08 mV/ECS) between the allylic acetates considered
(Table 1). ii) There was a different behavior for acetates bearing
a strained cyclopentenyl structure in comparison with others.
These strained substrates show a two-wave reduction process
whereas other substrates show only one 2-electron wave. There
appears some correlation between the electrochemical behavior
and the reactivity of the investigated substrates. However we are
not presently able to offer any rationalization to such a correlation.
The SmI2-mediated coupling of carbonyl compounds with allylic
phosphate is documented,8 and showed to proceed without Pd
catalysis. In contrast, only one example of such a coupling has been
described with allyl acetate, the SmI2/HMPA-mediated reaction of
allyl acetate with phenethyl methyl ketone to give the corre-
sponding homoallylic alcohol (Scheme 8).9 For this process, Ina-
naga suggested a mechanism going through initial ketyl formation,
subsequent attack the double bond, followed by b-elimination of
the acetoxy group to deliver the homoallylic alcohol.
This mechanism does not fit our results since it would lead to
optically active products from optically active substrates. Our
OH
OAc
OSmI2
R1
R2
H + H
R1
R2
SmI2
R1
R2
OAc
R1
R2
OAc
OSmI2
O
SmI2
OSmI2
R1 = -CH2-CH2-Ph
2 = -CH3
OH
R
H
R1
R2
R1
R2
OAc
- AcO
Scheme 8. Mechanism of diodosamarium-induced allylation of phenethyl methyl ketone suggested by Inanaga.9

O. Jacquet et al. / Tetrahedron 66 (2010) 222–226
225
Table 1
Reduction potential of allylic acetates measured by cyclic voltammetrya
endo-1
exo-1
Ph
OAc
OAc
OAc
OAc
OAc
Concentration (10ꢀ3 mmol/L)
E1 (mV/ECS)
8.00
ꢀ0.67
ꢀ0.92
6.35
ꢀ0.62
ꢀ1.03
6.35
ꢀ0.68
ꢀ1.05
7.15
d
6.30
d
9.30
d
5.20
d
E2 (mV/ECS)
ꢀ1.01
ꢀ1.08
ꢀ0.99
ꢀ1.00
a
NBuþ4 BFꢀ4 as electrolyte in THF (0.5 mol/L); scan rate 10 mV/s.
The chemoselectivity of the reaction could be tentatively
explained by the requirement of both steric and stereo-
electronic control (Scheme 9). steric control for the
coordination of SmI2 to the carbonyl of the allylic substrate
should explain the more difficult access for samarium species to
the acetato group and the lower reactivity of endo-1 compared to
the exo isomer.
Samarium diodide was prepared according to a reported
procedure.14
a
A
1H and 13C NMR spectra were recorded at 250 and 62.5 MHz,
respectively, with a Bruker AC 250 instrument. HRMS data were
obtained with a GC/MS Finnigan MAT-95 spectrometer. Flash
chromatography was carried out on silica gel (Merck 230–
240 mesh; 0.0040–0.0630 mm).
Sm(III)I2
I2Sm
SmI2
SmI2
O
O
SmI2OAc
O
O
stereoelectronic control
Scheme 9. Consecutive one-electron transfers for the formation of the allylsamarium complex. The first one being under strong stereoelectronic control.
Indeed for several other SmI2-induced reactions, a coordination
of the samarium species to some carbonyl function of the substrate
has been shown to be required for the reaction to proceed. Among
3.1.1. X-ray crystallography. X-ray diffraction data were collected
by using a Kappa X8 APPEX II Bruker diffractometer with graphite-
monochromated Mo K
a
radiation (l¼0.71073 Å). The temperature
these are the reduction of the
a
,b
-unsaturated esters,10 the de-
of the crystal was maintained at the selected value (100 K) by
means of a 700 series Cryostream cooling device to within an ac-
curacy of ꢁ1 K. The data were corrected for Lorentz polarization,
and absorption effects. The structures were solved by direct
methods using SHELXS-9715 and refined against F2 by full-matrix
least-squares techniques using SHELXL-9716 with anisotropic dis-
placement parameters for all non-hydrogen atoms. Hydrogen
atoms were located on a difference Fourier map and introduced
into the calculations as a riding model with isotropic thermal pa-
rameters. All calculations were performed by using the Crystal
Structure crystallographic software package WINGX.17
oxygenation of
a
-oxygenated esters.11 Such coordination appears to
be also requisite for the scarce SmI2-promoted reactions of acetates
with ketones that have been reported, i.e., the samarium-mediated
Reformatsky coupling reactions with ketones of a
-acetoxyesters12
or 2-pyridinemethyl acetates.13 In this latter example, 2-pyr-
idinemethyl acetates are active substrates toward ketones while 3
or 4-pyridinemethyl acetates and benzyl acetate are inert. In other
hand, we suggest that the success of the SmI2-mediated allylation
of cyclic ketones by allylic acetates depend upon a stereoelectronic
control of a SmI2-O-coordinated allylic acetate complex for the first
electron transfer. For strained allylic substrates, the requisite con-
formation allowing a rapid electron transfer would be highly
populated whereas it would be poorly populated for linear, cyclo-
heptenyl and cyclooctenyl substrates.
The absolute configuration was determined by refining the
Flack’s parameter using a large of Friedel’s pairs.18
CCDC 723105 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from the
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
In conclusion, through the use of stereochemically-biased and
enantiomeric allylic enriched substrates 1, we showed that palla-
dium catalysis was not necessarily involved in the samarium
diodide mediated coupling reaction of allylic acetates and cyclic
ketones. However, this was observed only for a restricted number of
strained allylic acetates that were reactive with cyclic ketone under
samarium diodide mediation and smooth conditions (THF, room
temperature). The conducted experiments would be in favor of the
Crystallographic Data for 2b.
Empirical formula
Formula wt, g/mol
Temp (K)
C16 H24
232.35
100(1)
0.71073
O
Cell volume (Å3)
Z
Density (calcd)
Absorb coeff (mmꢀ1
5315.0(8)
16
1.161
Wavelength
)
0.070
Crystal system
Space group
tetragonal
P43212
Reflections collected
Independent reflections
53,312
7432
(Rint¼9.22%)
0.0764
0.1891
0.2(3)
involvement of a
p-allyl samarium species as intermediate. For-
mation of this complex should be under strong stereoelectronic
control, via a requisite conformation being readily found in the
cyclopent-2-enyl series for the first electron transfer. Further
mechanistic studies would be required to provide a better un-
derstanding of such a control.
a (Å)
b (Å)
c (Å)
11.3270(7)
11.3270(7)
41.426(5)
Final R indices [I>2
s
(I)]
Final wR indices [I>2
Flack parameter
s
(I)]
3. Experimental section
3.1. General comments
3.1.2. Cyclopent-2-enol. Cerium trichloride heptahydrate (27.3 g,
73.6 mmol) was dissolved in 120 mL of methanol. Then cyclopent-
2-enone (6 g, 73 mmol) was introduced. After 5 min of vigorous
stirring, 5.6 g (147 mmol) of sodium borohydride were carefully
added portionwise and the resulting heterogeneous mixture was
stirred for 15 min at room temperature. Water was added dropwise
until obtention of a clear solution and then the mixture was
All reactions were carried out under argon using standard
Schlenk and vacuum line techniques. THF was dried over sodium/
benzophenone under an argon atmosphere.

226
O. Jacquet et al. / Tetrahedron 66 (2010) 222–226
extracted thrice with diethylether. The organic layers were col-
lected, dried over magnesium sulfate and the solvents were re-
moved under vacuum. Cyclopenten-2-ol was obtained as a colorless
oil (5.2 g, 85% yield) and was acylated without further purification.
1H NMR (CDCl3, 250 MHz): 1.65 (m, 2H), 2.26 (m, 2H), 2.5 (m,
1H), 4.90 (d, J¼5.4 Hz, 1H), 5.86 (dd, J¼2.2 and 5.7 Hz, 1H), 6.01 (dd,
J¼2.2 and 5.7 Hz, 1H).
3.2.2. exo-1-(30a,40,50,60,70,70a-Hexahydro-10H-40,70-meth-
ano)indenylcyclobutan-1-ol 2a. Yellow oil, 57% yield starting from
the exo-acetate 1 in the presence of a catalytic amount of Pd(PPh3)4.
1H NMR (CDCl3, 250 MHz): 1.41–1.59 (m, 6H), 1.63–1.79 (m, 4H),
2.06 (m, 2H), 2.17 (m, 1H), 2.27 (m, 2H), 2.88 (m, 1H), 2.99 (m, 1H),
5.65 (dt, J¼2.1 and 5.7 Hz, 1H), 5.89 (dt, J¼2 and 5.7 Hz, 1H). 13C
NMR (CDCl3, 62.5 MHz): 22.7, 22.9, 25.0, 29.4, 29.7, 33.8, 45.4, 52.9,
53.8, 68.0, 76.2, 129.1, 138.2. IR (neat): 3426, 3040, 2949, 2871, 1454,
1363, 1244. HRMS (EI): 204.1310, calcd: 204.1314.
3.1.3. Cyclopent-2-enyl acetate. Cyclopenten-2-ol (3.31 g, 39.4
mmol) was diluted in 20 mL of diethylether followed by the addition
and dissolution of 500 mg (4.1 mmol) of N,N-dimethylaminopyr-
idine. Then, triethylamine (7 mL, 50 mmol) and acetic anhydride
(4.2 mL, 45 mmol) were successively added at 0 ꢂC. The reaction
mixture was stirred one night at room temperature. Diethyl ether
(20 mL) was added and the mixture washed with a 1 M solution of
hydrochloric acid and a saturated solution of sodium hydro-
genocarbonate. The organic layer was dried over magnesium sulfate
and the solvents were removed under vacuum. The crude product
was then distilled under reduced pressure (70 ꢂC/20 mmHg) to af-
ford 3.45 g (70% yield) of a colorless oil.
3.2.3. exo-1-(30a,40,50,60,70,70a-Hexahydro-10H-40,70-meth-
ano)indenylcyclohexan-1-ol 2b. Colorless crystals, 70% yield starting
from the exo-acetate 1 in the presence of a catalytic amount of
Pd(PPh3)4.
Mp 85–88 ꢂC. 1H NMR (CDCl3, 250 MHz): 1.2 (m, 6H), 1.3–1.7 (m,
11H), 2.11 (m, 1H), 2.28 (m, 1H), 2.42 (dt, J¼3.6 and 9.6 Hz, 1H), 2.55
(q, J¼3 Hz, 1H), 2.94 (m, 1H), 5.68 (dt, J¼2.3 and 5.9 Hz, 1H), 5.78
(ddt, J¼0.8, 2.1 and 5.9 Hz, 1H). 13C NMR (CDCl3, 62.5 MHz): 22.0,
23.0, 24.9, 26.0, 35.0, 36.1, 39.2, 41.0, 41.4, 44.8, 52.6, 56.1, 73.2,
129.8, 136.9. IR (neat): 3422, 3043, 2949, 2875, 1451, 1363, 1240.
HRMS (EI): 232.1822, calcd: 232.1827.
1H NMR (CDCl3, 250 MHz): 1.7–1.9 (m, 1H), 2.0 (s, 3H), 2.2–2.3
(m, 1H); 2.3–2.4 (m, 1H), 2.4–2.65 (m, 1H), 5.65 (m, 1H), 5.8 (m, 1H),
6.1 (m, 1H). 13C NMR (CDCl3, 62.5 MHz): 21.2, 29.7, 31.0, 80.4, 129.2,
137.4, 170.9.
3.2.4. exo-1-(30a,40,50,60,70,70a-Hexahydro-10H-40,70-methano)indenyl-
4-phenylcyclohexan-1-ol 5a. White solid. 56% yield of the major
diastereomer.
3.1.4. exo-3a,4,5,6,7,7a-Hexahydro-1H-4,7-methanoindenyl acetate
exo-1. 1H NMR (CDCl3, 250 MHz): 1.1–1.6 (m, 6H), 2.05 (s, 3H), 2.35
(m, 2H), 2.45 (m, 1H), 3.15 (m, 1H), 5.6 (m, 1H), 5.8 (ddd, J¼6, 2 and
2 Hz, 1H), 6.05 (m, 1H). 13C NMR (CDCl3, 62.5 MHz): 21.3, 23.3, 24.7,
39.1, 39.4, 41.5, 50.9, 52.1, 81.2, 129.3, 141.7, 171.2. IR (neat): 2954,
2875, 1735, 1364, 1244, 1042, 1018, 948, 767. HRMS (EI): 192.1143,
calcd: 192.1150. GLC the enantiomers are separable overa Chiraldex-
Mp 76–79 ꢂC. 1H NMR (CDCl3, 250 MHz): 1.39–1.65 (m, 8H),
1.70–1.92 (m, 7H), 2.17 (m, 1H), 2.33 (m, 1H), 2.47 (m, 2H), 2.56 (m,
1H), 2.99 (m, 1H), 5.73 (dt, J¼2.1 and 5.7 Hz, 1H), 5.82 (dt, J¼2.1 and
5.7 Hz, 1H), 7.21–7.34 (m, 5H). 13C NMR (CDCl3, 62.5 MHz): 15.3,
23.0, 25.0, 35.1, 35.9, 39.2, 41.0, 41.4, 44.2, 45.0, 52.6, 57.5, 65.9, 72.6,
125.9, 126.9, 128.3, 129.8, 137.1, 147.4. IR (neat): 3425, 3031, 2976,
2865, 1708, 1363, 1244. HRMS (EI): 308.1804, calcd: 308.2140.
Enantiomers were separated analytically, on Chiralpak IA, hex-
b-PM column (15 m), isotherm program at 140 ꢂC, t1¼12.6 min,
20
t2¼13.3 min. [
a
]
ꢀ12 (CHCl3, c¼1) (66% ee, by chiral GLC analysis).
ane/isopropanol 75:25, flow 0.8 mL$minꢀ1
,
l¼225 nm, 293 K,
D
t1¼8.40 min, t2¼9.55 min.
3.1.5. endo-3a,4,5,6,7,7a-Hexahydro-1H-4,7-methanoindenyl acetate
endo-1. 1H NMR (CDCl3, 250 MHz): 1.1–1.7 (m, 6H), 2.05 (s, 3H), 2.1
(s, 1H), 2.3 (s, 1H), 2.85 (m, 2H), 5.6 (dm, J¼9 Hz, 1H), 5.7 (ddd, J¼6
and 2 Hz, 1H), 5.9 (ddd, J¼5 and 2 Hz, 1H). 13C NMR (CDCl3,
62.5 MHz): 21.0, 23.6, 24.6, 39.3, 40.5, 41.2, 46.3, 51.0, 78.7, 129.6,
137.1, 171.0. IR (neat): 2951, 2875, 1735, 1364, 1263, 1242, 1081, 1047,
1020, 748. HRMS (EI): 192.1143, calcd: 192.1150. GLC the enantio-
Acknowledgements
`
O.J. acknowledges the French ‘Ministere de la Recherche et de
0
´
l Enseignement Superieur’ for a Ph.D. fellowship.
References and notes
mers are separable over a Chiraldex-b-PM column (15 m), isotherm
20
program at 140 ꢂC, t1¼13.4 min, t2¼17.6 min. [
c¼1.15) (96% ee, by chiral GLC analysis).
a
]
þ98.6 (CHCl3,
1. (a) Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207–2293; (b) Denmark, S. E.;
Fu, J. Chem. Rev. 2003, 103, 2763–2793.
2. Tamaru, Y. Palladium-catalyzed reactions of allyl and related derivatives
with organoelectrophiles. In Handbook of organopalladium chemistry in
organic synthesis; Negishi, E., Ed.; J. Wiley & Sons: 2002; Vol. 2, pp 1917–
1943.
3. Tabuchi, T.; Inanaga, J.; Yamaguchi, M. Tetrahedron Lett. 1986, 27, 1195–1196.
4. Me´de´gan, S.; He´lion, F.; Namy, J.-L. Eur. J. Org. Chem. 2005, 4715–4722.
5. Tabuchi, T.; Inanaga, J.; Yamaguchi, M. Tetrahedron Lett. 1986, 27, 601–602.
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391–394.
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2586.
8. Araki, S.; Ho, M.; Ito, H.; Butsugan, Y. J. Organomet. Chem. 1987, 333, 329–335.
9. Ujikawa, O.; Inanaga, J.; Yamaguchi, M. Tetrahedron Lett. 1989, 21, 2837–2840.
10. Inanaga, J.; Sakai, S.; Handa, Y.; Yamaguchi, M.; Yokoyama, Y. Chem. Lett. 1991,
2117–2118.
11. Kusuda, K.; Inanaga, J.; Yamaguchi, M. Tetrahedron Lett. 1989, 30, 2945–2948.
12. Malapelle, A.; Abdallah, Z.; Doisneau, G.; Beau, J.-M. Angew. Chem., Int. Ed 2006,
43, 846–849.
13. Weitgenant, J. A.; Mortison, J. D.; Helquist, P. Org. Lett. 2005, 7, 3609–3612.
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15. Sheldrick, G. M. SHELXS-97, Program for Crystal Structure Solution; University of
Go¨ttingen: Go¨ttingen, Germany, 1997.
16. Sheldrick, G. M. SHELXL-97, Program for the Refinement of Crystal Structures from
Diffraction Data; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
17. Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837–838.
D
3.2. General procedure for the samarium diodide mediated
coupling between allylic acetates and electrophiles
Equimolar quantities of allylic acetate (0.5 mmol) and electro-
phile (0.5 mmol) were diluted in 1 mL of dry THF and were then
added to 11 mL (1.1 mmol) of a 0.1 M solution of SmI2 in THF. The
resulting mixture was stirred for 15 h at room temperature. After
hydrolysis with a 1 M solution of hydrochloric acid the mixture was
extracted thrice with diethylether, the organic layers were dried
over magnesium sulfate and the solvents were removed under
vacuum. The crude product was then purified by flash chroma-
tography on silica gel (heptane/ethyl acetate: 9/1).
3.2.1. 1-(Cyclopent-20-enyl)cyclohexan-1-ol. Colorless oil, 58% yield
(70% in the presence of a catalytic amount of Pd(PPh3)4).
1H NMR (CDCl3, 250 MHz): 1.30–1.70 (m, 8H), 1.90 (m, 4H), 2.35
(m, 2H), 2.70 (m, 1H), 5.75 (dq, J¼2.2 and 6 Hz, 1H), 5.92 (dq, J¼2.2
and 6 Hz, 1H). 13C NMR (CDCl3, 62.5 MHz): 19.4, 21.9, 24.4, 29.4,
32.2, 35.5, 52.1, 130.1, 133.8. IR (neat): 3460, 3052, 2931, 2850, 1447,
1260. HRMS (EI): 166.1352, calcd: 166.1358.
18. Flack, H. D. Acta Crystallogr. 1983, A39, 876–881.