Arene-catalysed lithiation of phenyl- and 1,1-diphenylcyclopropane: synthetic applications

Article abstract of DOI:10.1016/j.tet.2007.03.102

The reaction of phenylcyclopropane (1) with an excess of lithium and a catalytic amount of DTBB (2.5% molar) in THF at room temperature, followed by treatment with an electrophile [Me₃SiCl, PhMe₂SiCl, t-BuCHO, PhCHO, Me₂CO

Full text of DOI:10.1016/j.tet.2007.03.102

Tetrahedron 63 (2007) 4655–4662
Arene-catalysed lithiation of phenyl- and 1,1-
diphenylcyclopropane: synthetic applications
*
Cecilia Gomez, Victor J. Lillo and Miguel Yus
*
ꢀ
Departamento de Quꢀımica Orgaꢀnica, Facultad de Ciencias and Instituto de Sꢀıntesis Orgaꢀnica (ISO), Universidad de Alicante,
Apdo. 99, 03080 Alicante, Spain
Received 8 February 2007; revised 28 February 2007; accepted 16 March 2007
Available online 21 March 2007
This paper is dedicated to Professor Adalbert Maercker, a pioneer in dilithium compounds chemistry, on the occasion of his 75th birthday
Abstract—The reaction of phenylcyclopropane (1) with an excess of lithium and a catalytic amount of DTBB (2.5% molar) in THF at room
temperature, followed by treatment with an electrophile [Me3SiCl, PhMe2SiCl, t-BuCHO, PhCHO, Me2CO, Et2CO, (CH2)5CO, adamantan-
2-one, i-Pr2CO, di(cyclopropyl)ketone] and final hydrolysis with water leads to allylic products 10 or 11 depending on the structure of the
electrophile: whereas for chlorosilanes or crowded ketones g-products 11 are isolated, for aldehydes and non-congested ketones a-products
10 are formed. The application of the same protocol to 1,1-diphenylcyclopropane (7) leads to a mixture of products 13–15 resulting from the
introduction of one or two electrophilic fragments to the open-chain mono- or dilithiated intermediate: also in this case the regiochemistry of
the reaction is governed by steric reasons.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
at room temperature required ultrasonication and more than
one day to take place. After quenching with MeOH or
MeOD the dimer 2 or 3 was obtained, intermediates 4–6 be-
ing proposed to be involved in the process (Scheme 1). It is
supposed that after generation of the dilithio derivative 4 a b-
elimination of lithium hydride took place (it was isolated and
characterised) giving the delocalised allyllithium derivative
5, which under the assayed reaction conditions, and through
a new electron transfer process, undergoes dimerisation to
form the corresponding dimeric tetralithio intermediate 6
as a mixture of diastereomers. Final treatment with MeOH
or MeOD affords the final product 2 or 3 (Scheme 1).
From an electronic point of view, cyclopropanes are more
similar to olefins than to other cycloalkanes: in fact, instead
of having a 25% s-character (corresponding to a pure sp3-
hybridised carbon atom) in the simplest cyclopropane the
carbon–hydrogen bonds have a 33% s-character whereas the
carbon–carbon bonds have a 17% s-character.1 These elec-
tronic characteristics are a consequence of the great strain
of the small cyclopropane ring, which also has an important
influence on its reactivity, so the cyclopropane ring usually
suffers easy ring opening by means of different reagents.
Concerning the lithiation of cyclopropane derivatives with
lithium metal, it does not work with non-activated systems
(cyclopropane itself or alkylated derivatives),2 but cyclopro-
panes substituted by unsaturated groups, such as vinyl or
phenyl moieties, can be used for the reductive ring opening:
in this case, the electron transfer from the metal goes to the
p* orbital of the substituent and from there it is transferred
to the low energy adjacent s* orbital of a carbon–carbon
bond of the cyclopropane ring, thus facilitating its cleavage
giving initially the corresponding radical anion stabilised by
resonance.3 Recently Maercker et al. reported4 that the lith-
iation of phenylcyclopropane (1) with lithium metal in THF
D
D
i,ii
i,iii
Ph
Ph
2 Ph
Ph
Ph
D
D
2
1
3
Li
Li
Li
Li
Li
Ph
Li
Ph
Ph
Ph
Li
5
4
6
Scheme 1. Reagents and conditions: (i) Li, THF, ))), 20 ꢀC; (ii) MeOH;
(iii) MeOD.
Keywords: Arene-catalysed lithiation; Phenylcyclopropane; 1,1-Diphenyl-
cyclopropane; Reductive ring opening; Electrophilic substitution; Allyl-
lithium intermediates.
* Corresponding authors. Fax: +34 965 903549; e-mail addresses:
cgomez@ua.es; yus@ua.es
In the case of 1,1-diphenylcyclopropane (7), its lithiation
took place under milder reaction conditions (Li, THF,
ꢁ30 ꢀC, 5 h) than for phenylcyclopropane giving, after
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.03.102

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C. Goꢀmez et al. / Tetrahedron 63 (2007) 4655–4662
Table 1. Lithiation of phenylcyclopropane (1) and reaction with electro-
philes—isolation of products 10 or 11
quenching with MeOD, the dideuterio compound 8 with
high deuterium incorporation (96%). Here the proposed
more stable dilithio intermediate 9 behaves differently
than 4 not suffering dimerisation (Scheme 2).4
Entry Electrophile
Producta
No. Yieldb (%)
1
2
Me3SiCl
11a 44
Ph
Ph
SiMe3
PhMe2SiCl
11b 40
SiMe2Ph
OH
Li
Li
D
D
i,ii
Ph
Ph
Ph
Ph
Ph
Ph
8
3
t-BuCHO
10c 42c
9
7
Ph
Ph
Scheme 2. Reagents and conditions: (i) Li, THF, ꢁ30 ꢀC; (ii) MeOD.
OH
OH
4
5
PhCHO
Me2CO
10d 34d
10e 59
In this paper we study the application of an arene-catalysed
lithiation5 to the reductive ring opening of both phenyl- and
1,1-diphenylcyclopropane (1 and 7, respectively) in order to
trap the intermediates 4 (or 5) and 9,6 respectively, with dif-
ferent electrophiles to explore the synthetic possibilities of
the reductive ring opening of the starting materials 1 and 7.
Ph
Ph
OH
OH
6
7
Et2CO
10f 45
10g 56
Ph
Ph
Ph
2. Results and discussion
(CH2)5CO
2.1. Lithiation of phenylcyclopropane (1)
The reaction of commercially available phenylcylopropane
(1) with an excess of lithium (1/7 molar ratio; theoretical
1/2 molar ratio)7 and a catalytic amount of 4,40-di-tert-butyl-
biphenyl (DTBB; 1/0.05 molar ratio; 2.5% molar) in THF
for 4 h at room temperature afforded, after treatment with
a chlorosilane or a carbonyl compound as electrophile
[E¼Me3SiCl, PhMe2SiCl, t-BuCHO, PhCHO, Me2CO,
Et2CO, (CH2)5CO, adamantan-2-one, i-Pr2CO, di(cyclopro-
pyl)ketone] at 0 ꢀC and final hydrolysis with water, the
corresponding allylic compounds 10 or 11 (Scheme 3 and
Table 1).8
8
9
Adamantan-2-one
10h 38
OH
OH
i-Pr2CO
11i 42e
Ph
Ph
OH
10
Di(cyclopropyl) ketone
11j 51f
All products 10 and 11 were >95% pure (GLC and 300 MHz 1H NMR).
Isolated yield after purification by column chromatography (silica gel,
hexane/ethyl acetate) based on the starting phenylcyclopropane (1).
A 4/1 anti/syn diastereomer (1H NMR) mixture was obtained.
A 1.5/1 anti/syn diastereomer (1H NMR) mixture was obtained.
A ca. 10% of the corresponding saturated alcohol was also detected (GC–
MS).
a
b
X
c
d
e
i-iii
or
Ph
Ph
X
Ph
11
1
10
f
A 9% of the corresponding saturated alcohol was also detected (GC–MS).
Scheme 3. Reagents and conditions: (i) Li, DTBB (2.5% molar), THF, rt,
4 h; (ii) E¼Me3SiCl, PhMe2SiCl, t-BuCHO, PhCHO, Me2CO, Et2CO,
(CH2)5CO, adamantan-2-one, i-Pr2CO, di(cyclopropyl) ketone, 0 ꢀC,
30 min; (iii) H2O, 0 ꢀC to rt, 1 h.
compounds the reaction works through the intermediate
5a and the chair-like transition state 12,10 since for bulky
electrophiles the less congested intermediate 5g takes part
exclusively in the reaction.11 In the case of using aldehydes
as electrophiles, the corresponding mixture of diastereomers
was obtained (Table 1, entries 3 and 4), the major one being
the anti-configurated, the expected one according to the
model 12 for the corresponding transition state.
The result of this reaction clearly indicates that under the as-
sayed conditions, the initially formed dilithio intermediate 4
suffers rapid lithium hydride elimination to give the allylic
intermediate 5, which is the real lithium reagent in the reac-
tion with the electrophile. The reaction is rather regioselec-
tive depending on the nature and/or structure of the
electrophile and is governed by steric reasons: with bulky
chlorosilanes only (E)-allylic products 11a,b were isolated
(g-substitution; Table 1, entries 1 and 2), no other products
from the reaction with the electrophile [either 10c,d or (Z)-
11c,d] being detected (<5%) from the crude reaction mix-
ture.9 When a sterically non-hindered carbonyl compound
was used as electrophile an a-substitution was always ob-
served yielding compounds 10c–h (Table 1, entries 3–8),
whereas for crowded ketones like di(cyclopropyl) ketone
or di(isopropyl) ketone products 11i,j resulting from a g-
attack were the only reaction products isolated (Table 1,
entries 9 and 10). It seems that for non-bulky carbonyl
‡
H
R1
Li
Li
Ph
Li
Ph
Ph
O
R2
5
5
H
12
Concerning the role of the arene as catalyst in the electron
transfer reaction from the metal to the substrate to be lithi-
ated, in the absence of DTBB the starting material 1 was

C. Goꢀmez et al. / Tetrahedron 63 (2007) 4655–4662
4657
recovered under the same reaction conditions shown in
Scheme 3. The use of a stoichiometric amount of lithium
(1/Li, 1/2.1 molar ratio) and the same amount of the arene
(2.5% molar) led to a low conversion (less than 40%) under
the same reaction conditions. Finally, when the stoichio-
metric version of the DTBB-promoted reaction was used
(1/LiDTBB, 1/2.1 molar ratio) under the same reaction con-
ditions, only about 30% conversion was observed.7,12
for dialkyl ketones for which compounds 14 (resulting
from the intermediate 16g) were partially (Table 2, entry
5) or totally (Table 2, entries 6 and 8) formed. Thus, for
the lithiated intermediates from 1,1-diphenylcyclopropane
(7) (see species 9 and 16) we found a reactivity parallel to
that reported in Table 1: for hindered ketones the less con-
gested g-attack is preferred to the corresponding a-one indi-
cating that steric factors play an important role in the
regiochemistry of the process. From a preparative point of
view it is worthy to note that in general compounds 13–15
have been separated and purified chromatographically, so
they could be easily isolated in pure form.
2.2. Lithiation of 1,1-diphenylcyclopropane (7)
When the same reaction shown in Scheme 3 was applied to
1,1-diphenylcyclopropane (7),13 but using a little bit more
catalyst loading (ca. 4% molar ratio) and lower temperature
(ꢁ50 ꢀC) for the SE step, compounds 13–15 were obtained
(Scheme 4 and Table 2). In this case, the intermediate 9
initially formed, instead of suffering elimination of lithium
hydride, takes partially or totally a proton from the reaction
medium14 to generate the monolithiated intermediates 16,
which afford final compounds 13 and 14. In some cases,
for very reactive electrophiles such as chlorosilanes (Table
2, entries 1 and 2) and pivalaldehyde (Table 2, entry 3) the
dianion 9 could be trapped, so the corresponding disub-
stituted compounds 15 were also isolated. In general for
carbonyl compounds, products 13 (resulting from the
intermediate 16a) were mainly (Table 2, entries 3 and 5)
or exclusively (Table 2, entries 4 and 7) obtained, except
Ph
Li
Ph
Li
Ph
Ph
16
16
Ph
X
X
Ph
Ph
i-iii
+
or
Ph
X
Ph
Ph
X
Ph
Ph
7
14
13
15
Scheme 4. Reagents and conditions: (i) Li, DTBB (4% molar), THF, 0 ꢀC,
1.5 h; (ii) E¼Me3SiCl, PhMe2SiCl, t-BuCHO, PhCHO, Me2CO, Et2CO,
i-Pr2CO, (CH2)5CO, ꢁ50 ꢀC, 30 min; (iii) H2O, ꢁ50 ꢀC to rt, 1 h.
Table 2. Lithiation of 1,1-diphenylcyclopropane (7) and reaction with electrophiles (E)—isolation of products 13–15
Entry
Electrophile
Productsa
Yieldb (%)
19+36
Ph
Ph
+
+
(13a)
(13b)
(15a)
(15b)
(15c)
1
Me3SiCl
Ph
SiMe3
Ph
Ph
SiMe3
Ph
SiMe3
Ph
2
3
PhMe2SiCl
15+54
Ph
SiMe2Ph
SiMe2Ph
Ph
SiMe2Ph
Ph
(13c)
+
Ph
HO
t-BuCHO
Ph
55+23c
OH
OH
Ph
(13d)
Ph
4
5
6
7
PhCHO
Me2CO
Et2CO
47
Ph
OH
Ph
Ph
+
(14e)
(13e)
56+6
50
Ph
Ph
OH
OH
Ph
(14f)
Ph
OH
Ph
(13g)
(CH2)5CO
42
Ph
OH
Ph
OH
(14h)
8
t-Bu2CO
Ph
48
All products 13–15 were >95% pure (GLC and 300 MHz 1H NMR).
Isolated yield after purification by column chromatography (silica gel, hexane/ethyl acetate) based on the starting material 7.
Only one diastereomer was detected by NMR and GLC.
a
b
c

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C. Goꢀmez et al. / Tetrahedron 63 (2007) 4655–4662
3. Conclusions
the solution was stirred at 0 ꢀC for 30 min. Then it was
hydrolysed with water (5 mL) allowing the temperature
to rise to room temperature. The resulting mixture was
extracted with diethyl ether (3ꢃ5 mL) and the organic
layer was dried over anhydrous MgSO4 and evaporated
(15 Torr). The resulting residue was then purified by column
chromatography (silica gel, hexane/ethyl acetate) to yield
the title products. Yields are included in Table 1; physical,
spectroscopic and analytical data, as well as literature refer-
ences for known compounds, follow.
The chemistry described here showed that the reductive
opening of both phenylcyclopropane and 1,1-diphenylcyclo-
propane using an arene-catalysed lithiation could have
synthetic applications where the cyclopropyl ring starting
materials are readily available. This procedure is applicable
to the preparation of polyfunctionalised molecules, espe-
cially alcohol derivatives, the regioselectivity of the process
being rationalised considering mainly steric factors of both
the lithiated intermediate and the electrophile used.
4.2.1. (E)-3-Trimethylsilyl-1-phenyl-1-propene (11a).
Colourless oil, 88 mg; tR¼10.5 min; Rf (hexane/ethyl ace-
tate 8/2)¼0.89; n (film) 3061 (]CH) cmꢁ1; dH (300 MHz)
0.00 (9H, s, 3ꢃCH3), 1.62 (2H, d, J¼6.7, CH2), 6.18–6.22
(2H, m, CH]CH), 7.08–7.28 (5H, m, 5ꢃArH); dC
(75 MHz) ꢁ1.9 (CH3), 23.9 (CH2), 125.5, 126.2, 127.8,
128.2, 128.4 (CH]CH, ArCH), 138.5 (ArC); m/z 190
(M+, 31%), 115 (11), 73 (100).17
4. Experimental
4.1. General
For general information, see Ref. 15. All lithiation reactions
were carried out under argon atmosphere in oven-dried
glassware. All commercially available reagents (Acros, Al-
drich, Fluka) were used without further purification (chloro-
trimethylsilane and benzaldehyde were distilled before use).
Commercially available anhydrous THF (99.9%, water con-
tent ꢂ0.006%, Fluka) was used as solvent in all the lithiation
reactions. IR spectra were measured (film) with a Nicolet
Impact 400 D-FT Spectrometer. NMR spectra were recorded
in the Technical Services of the University of Alicante with
a Bruker AC-300 or Bruker AC-400 spectrometer using
CDCl3 as solvent and TMS as internal standard; chemical
shifts are given in parts per million and coupling constants
(J) are given in hertz. 13C NMR assignments were made
on the basis of DEPT experiments. LRMS were measured
with Shimadzu GC/HS QP-5000 and Hewlett–Packard
EM/CG-5973A spectrometers, and HRMS were measured
in the Technical Services of the University of Alicante
with a Finnigan MAT95 S spectrometer, fragment ions in
m/z with relative intensities (%) in parentheses. The purity
of volatile products and the chromatographic analyses
(GLC) were determined with a Hewlett–Packard HP-6890
instrument equipped with a flame ionisation detector and
a 30 m HP-5 capillary column (0.32 mm diam., 0.25 mm
film thickness), using nitrogen (2 mL/min) as carrier gas,
Tinjector¼275 ꢀC, Tdetector¼300 ꢀC, Tcolumn¼60 ꢀC (3 min)
and 60–270 ꢀC (15 ꢀC/min), P¼40 kPa; retention times
(tR) are given under these conditions. Thin layer chromato-
graphy (TLC) was carried out on Merck plastic sheets coated
with silica gel 60 F254. Melting points were obtained with an
MPA100 Optimelt SRS apparatus. Lithium powder, which
can be prepared from commercially available lithium gran-
ules (99%, high sodium content, Aldrich) as it was already
reported by us,16 was supplied by Medalchemy S.L. and
Chemetall GmbH.
4.2.2. (E)-3-Dimethylphenylsilyl-1-phenyl-1-propene
(11b). Colourless oil, 106 mg; tR¼15.4 min; Rf (hexane/
ethyl acetate 8/2)¼0.73; n (film) 3068 (]CH) cmꢁ1; dH
(400 MHz) 0.32 (6H, s, 2ꢃCH3), 1.90 (2H, d, J¼6.8, CH2),
6.20–6.24 (2H, m, CH]CH), 7.14–7.54 (10H, m,
10ꢃArH); dC (100 MHz) ꢁ3.3 (CH3), 23.0 (CH2), 125.5,
126.3, 127.1, 127.8, 128.4, 128.9, 129.1, 133.6 (CH]CH,
ArCH), 138.4, 138.5 (ArC); m/z 252 (M+, 11%), 136 (14),
135 (100).18
4.2.3. syn/anti-2,2-Dimethyl-4-phenyl-5-hexen-3-ol (10c).
Colourless oil, 90 mg; tR (anti-isomer)¼11.7 min, tR (syn-
isomer)¼11.5 min; Rf (hexane/ethyl acetate 8/2)¼0.86
(anti+syn-isomers); n (film) 3456 (OH), 3062 (]CH) cmꢁ1
;
dH (400 MHz) 0.88 [9H, s, C(CH3)3 syn-isomer], 0.91 [9H, s,
C(CH3)3 anti-isomer], 1.46 (1H, d, J¼4.1, CHOH syn-iso-
mer), 1.75 (1H, d, J¼4.6, CHOH anti-isomer), 3.53–3.63
(2H, m, CHCH]CH2, CHOH anti+syn-isomers), 5.00–
5.17 (2H, m, CHCH]CH2 anti+syn-isomers), 6.11–6.18
(1H, m, CHCH]CH2 syn-isomer), 6.20–6.30 (1H, m,
CHCH]CH2 anti-isomer), 7.17–7.32 (5H, m, 5ꢃArH,
anti+syn-isomers); dC (100 MHz) 26.7 (CH3 anti-isomer),
26.8 (CH3 syn-isomer), 35.9 [C(CH3)3 syn-isomer], 36.0
[C(CH3)3 anti-isomer], 52.8 (CHCH]CH2 anti-isomer),
53.8 (CHCH]CH2 syn-isomer), 81.5 (CHOH syn-isomer),
81.6 (CHOH anti-isomer), 114.8 (CH2 syn-isomer), 117.2
(CH2 anti-isomer), 126.3, 127.9, 128.6 (ArCH anti-isomer),
126.7, 128.7, 128.9 (ArCH syn-isomer), 138.9 (CHCH]
CH2 anti+syn-isomers), 141.6 (ArC syn-isomer), 144.5
(ArC anti-isomer); m/z (anti-isomer) 186 (M+ꢁH2O), 119
(10), 118 (100), 117 (61), 115 (21), 91 (17), 87 (17), 69
(14); m/z (syn-isomer) 186 (M+, 1%), 129 (10), 119 (11),
118 (100), 117 (61), 115 (19), 91 (15), 87 (16), 69 (13).19
4.2. DTBB-catalysed lithiation of cyclopropylbenzene
(1). Isolation of compounds 10 and 11. General
procedure
4.2.4. syn/anti-1,2-Diphenyl-3-buten-1-ol (10d). Colour-
less oil, 80 mg; tR (anti+syn-isomers)¼14.7 min; Rf
(hexane/ethyl acetate)¼0.34; n (film) 3425 (OH), 3061
(]CH) cmꢁ1; dH (300 MHz) 1.95 (1H, s, OH anti-isomer),
2.32 (1H, s, OH syn-isomer), 3.55 (1H, dd, J¼8.3,
CHCH]CH2 anti-isomer), 3.63 (1H, dd, J¼8.1, 8.0,
CHCH]CH2 syn-isomer), 4.82–5.00 (3H, m, CHOH anti+
syn-isomers, CH]CH2 anti+syn-isomers), 5.84–5.96 (1H,
m, CH]CH2 syn-isomer), 6.18–6.31 (1H, m, CH]CH2
To a green suspension of lithium powder (49 mg, 7 mmol),
and DTBB (13 mg, 0.05 mmol) in THF (3 mL) was added
dropwise cyclopropylbenzene (0.130 mL, 1 mmol) at room
temperature and the resulting mixture was stirred for 4 h at
the same temperature. To the resulting deep red solution
was added the corresponding electrophile (1.2 mmol) and

C. Goꢀmez et al. / Tetrahedron 63 (2007) 4655–4662
4659
anti-isomer), 7.33–7.43 (10H, m, 10ꢃArH anti+syn-iso-
mers); dC (75 MHz) 58.5 (CHCH]CH2 syn-isomer), 59.2
(CHCH]CH2 anti-isomer), 117.2 (CH2 syn-isomer),
118.4 (CH2 anti-isomer), 126.6, 126.6, 127.0, 127.4,
127.8, 127.9, 128.1, 128.3, 128.7, 128.7 (ArCH anti+syn-
isomers), 137.6 (CH]CH2 anti-isomer), 137.8 (CH]CH2
syn-isomer), 140.6, 141.8 (ArC anti+syn-isomers); m/z
(anti-isomer) 206 (M+ꢁH2O, 6%), 119 (10), 118 (100),
117 (45), 116 (10), 115 (28), 107 (78), 91 (14), 79 (48), 77
(29); m/z (syn-isomer) 206 (M+ꢁH2O, 5%), 119 (10), 118
(100), 117 (45), 116 (10), 115 (28), 107 (79), 91 (14), 79
(45), 77 (27).20
4.2.9. (E)-3-Isopropyl-2-methyl-6-phenyl-5-hexen-3-ol
(11i). Colourless oil, 102 mg; tR¼14.7 min; Rf (hexane/ethyl
acetate 8/2)¼0.38; n (film) 3485 (OH), 3059 (]CH) cmꢁ1
;
dH (400 MHz) 0.96–1.01 [12H, m, 2ꢃCH(CH3)2], 1.98 [2H,
m, CH(CH3)2], 2.47 (2H, d, J¼7.5, CH2), 6.22–6.29 (1H, m,
ArCH]CH), 6.44 (1H, d, J¼15.9, ArCH]CH), 7.17–7.36
(5H, m, 5ꢃArH); dC (100 MHz) 17.3, 17.6 [CH(CH3)2],
34.2 [CH(CH3)2], 37.6 (CH2), 77.4 (COH), 126.0, 126.8,
127.0, 128.5, 132.4 (CH]CH, ArCH), 137.5 (ArC); m/z
214 (M+ꢁH2O, 2%), 189 (27), 118 (42), 117 (36), 116
(11), 115 (72), 91 (21), 71 (100), 55 (13).19
4.2.10. (E)-1,1-Dicyclopropyl-4-phenyl-3-buten-1-ol
(11j). Brownish oil, 120 mg; tR¼15.3 min; Rf (hexane/ethyl
acetate 8/2)¼0.36; n (film) 3576, 3474 (OH), 3088
(]CH) cmꢁ1; dH (300 MHz) 0.30–0.46 (8H, m, 4ꢃring
CH2), 0.85–0.92 (2H, m, 2ꢃring CH), 2.50 (2H, d, J¼6.1,
CH]CHCH2), 6.36–6.49 (2H, m, CH]CH), 7.20–7.38
(5H, m, 5ꢃArH); dC (75 MHz) ꢁ0.5, 0.8 (ring CH2), 18.8
(ring CH), 46.3 (CH]CHCH2), 70.9 (COH), 126.0, 126.2,
127.1, 128.5, 132.9 (CH]CH, ArCH), 137.6 (ArC); m/z
211 (M+ꢁOH, 15%), 210 (84), 195 (22), 182 (16), 181
(37), 179 (13), 178 (13), 169 (12), 168 (17), 167 (87), 166
(29), 165 (53), 155 (11), 154 (22), 153 (29), 152 (31), 141
(33), 129 (22), 128 (29), 119 (43), 117 (26), 116 (10), 115
(48), 105 (13), 103 (10), 92 (11), 91 (100), 79 (10), 77
(19), 65 (10); HRMS: M+ꢁH2O, found 210.1400, C16H18
requires 210.1409.
4.2.5. 2-Methyl-3-phenyl-4-penten-2-ol (10e). Colourless
oil, 108 mg; tR¼10.0 min; Rf (hexane/ethyl acetate 8/2)¼
0.20; n (film) 3440 (OH), 3062 (]CH) cmꢁ1; dH
(400 MHz) 1.17 (3H, s, CH3), 1.21 (3H, s, CH3), 1.60 (1H,
s, OH), 3.27 (1H, d, J¼9.7, CHCH]CH2), 5.12–5.22 (2H,
m, CH]CH2), 6.25–6.37 (1H, m, CH]CH2), 7.20–7.35
(5H, m, 5ꢃArH); dC (100 MHz) 27.6, 27.8 (CH3), 61.8
(CHCH]CH2), 72.2 (COH), 117.8 (CH]CH2), 126.7,
128.3, 129.1 (ArCH), 137.7 (CH]CH2), 141.1 (ArC); m/z
161 (M+ꢁCH3, 1%), 119 (10), 118 (100), 117 (87), 116
(12), 115 (35), 91 (18), 59 (57).21
4.2.6. 3-Ethyl-4-phenyl-5-hexen-3-ol (10f). Colourless oil,
97 mg; tR¼12.0 min; Rf (hexane/ethyl acetate 8/2)¼0.53; n
(film) 3479 (OH), 3062 (]CH) cmꢁ1; dH (400 MHz) 0.82
(3H, dd, J¼7.6, 7.3, CH3), 0.88 (3H, dd, J¼7.6, 7.3, CH3),
1.20–1.29 (1H, m, CH2CH3), 1.30–1.38 (1H, m, CH2CH3),
1.58 (1H, s, OH), 3.34 (1H, d, J¼9.6, CHCH]CH2), 5.07–
5.15 (2H, m, CH]CH2), 6.27–6.37 (1H, m, CH]CH2),
7.19–7.33 (5H, m, 5ꢃArH); dC (100 MHz) 7.6, 7.7 (CH3),
28.1, 28.7 (CH2CH3), 57.3 (CHCH]CH2), 76.0 (COH),
116.7 (CH]CH2), 126.5, 128.3, 129.2 (ArCH), 138.0
(CH]CH2), 141.4 (ArC); m/z 186 (M+ꢁH2O, 1%), 119
(10), 118 (100), 117 (49), 116 (11), 115 (33), 91 (17), 87
(84), 69 (15), 57 (36).22
4.3. Preparation of 1,1-diphenylcyclopropane (7)
To a mixture of LiAlH4 (20 mmol) in THF (30 mL) at 0 ꢀC,
was added dropwise a solution of 1,1-dibromo-2,2-diphenyl-
cyclopropane12 (15 mmol) in THF (15 mL) and the solution
was stirred at room temperature overnight. The resulting
mixture was cooled at 0 ꢀC and was hydrolysed with H2O
(1 mL), NaOH 10% (1 mL) and H2O again (3 mL), filtered
through Celite, dried over anhydrous MgSO4 and evaporated
(15 Torr). The resulting white solid was dissolved in THF
(30 mL) and the solution was cooled at ꢁ30 ꢀC, then
18 mL of n-butyllithium (1.6 M in hexane) was added drop-
wise, the mixture was stirred for 45 min and then it was
hydrolysed with water (10 mL) allowing the temperature
to rise to room temperature. The solution was extracted
with hexane (3ꢃ10 mL) and the organic layer was dried
over MgSO4 and evaporated (15 Torr) to obtain 13.1 mmol
of pure 1,1-diphenylcyclopropane (>95% GLC). Its spectro-
scopic and chromatographic data are similar to those de-
scribed in the literature.13
4.2.7. 1-(1-Phenylallyl)-1-cyclohexanol (10g). Colourless
oil, 127 mg; tR¼13.7 min; Rf (hexane/ethyl acetate 8/2)¼
0.44; n (film) 3443 (OH), 3061 (]CH) cmꢁ1; dH
(300 MHz) 1.11–1.73 (10H, m, 5ꢃring CH2), 3.24 (1H, d,
J¼9.7, CHCH]CH2), 5.07–5.18 (2H, m, CH]CH2),
6.25–6.38 (1H, m, CH]CH2), 7.19–7.33 (5H, m, 5ꢃArH);
dC (75 MHz) 21.8, 25.6, 35.5, 35.8 (4ꢃring CH2), 61.0
(CHCH]CH2), 72.6 (COH), 117.3 (CH]CH2), 126.5,
128.2, 129.2 (ArCH), 137.6 (CH]CH2), 140.9 (ArC); m/z
198 (M+ꢁH2O, 1%), 119 (11), 118 (100), 117 (38), 115
(26), 99 (59), 91 (13), 81 (53), 55 (11).23
4.4. DTBB-catalysed lithiation of 1,1-diphenylcyclo-
propane (7). Isolation of compounds 13–15. General
procedure
4.2.8. 2-(1-Phenylallyl)-2-adamantanol (10h). White
solid, 107 mg; mp 117 ꢀC; tR¼17.2 min; Rf (hexane/ethyl
acetate 8/2)¼0.62; n (KBr) 3574 (OH), 3061 (]CH) cmꢁ1
;
dH (400 MHz) 0.67–2.35 (14H, m, 10ꢃring CH2, 4ꢃring
CH), 3.97 (1H, d, J¼9.5, CHCH]CH2), 5.06–5.15 (2H,
m, CH]CH2), 6.27–6.37 (1H, m, CH]CH2), 7.02–7.36
(5H, m, 5ꢃArH); dC (100 MHz) 27.0, 27.1 (2ꢃring CH),
32.9, 33.2, 33.4, 34.1 (4ꢃring CH2), 34.4, 34.9 (2ꢃring
CH), 38.4 (1ꢃring CH2), 53.6 (CHCH]CH2), 75.9
(COH), 116.5 (CH]CH2), 126.5, 128.3, 129.2, 137.6
(CH]CH2, ArCH), 141.2 (ArC); m/z 250 (M+ꢁH2O, 5%),
152 (12), 151 (100), 118 (33), 117 (10), 91 (14).24
To a green suspension of lithium powder (49 mg, 7 mmol),
and DTBB (20 mg, 0.075 mmol) in THF (2 mL) was added
dropwise 1,1-diphenylcyclopropane (1 mmol) at 0 ꢀC and
the resulting mixture was stirred for 1.5 h at the same tem-
perature. Then the red solution was cooled at ꢁ50 ꢀC and
the corresponding electrophile (2 mmol) was added drop-
wise and stirred for 30 min. The resulting mixture was
hydrolysed with water (5 mL) allowing the temperature to
rise to room temperature, and then it was extracted with

4660
C. Goꢀmez et al. / Tetrahedron 63 (2007) 4655–4662
diethyl ether (3ꢃ5 mL), the organic layer was dried over
anhydrous MgSO4 and evaporated (15 Torr). The resulting
residue was then purified by column chromatography (silica
gel, hexane/ethyl acetate) to yield the title compounds.
Yields are included in Table 2; physical, spectroscopic and
analytical data, as well as literature references for known
compounds, follow.
(CH), 125.8, 126.4, 127.4, 128.0, 128.7, 130.6 (ArCH),
141.2, 146.3 (ArC); m/z 264 (M+ꢁH2O, 1%), 197 (10),
196 (59), 195 (17), 168 (14), 167 (100), 165 (14), 117
(11), 91 (19); HRMS: M+ꢁH2O, found 264.1861, C20H24
requires 264.1878.
4.4.6. 2,2,8,8-Tetramethyl-4,4-diphenyl-3,7-nonanediol
(15c). Colourless oil, 88 mg; tR¼20.3 min; Rf (hexane/ethyl
4.4.1. 1,1-Diphenylpropyl(trimethyl)silane (13a). Colour-
less oil, 54 mg; tR¼14.8 min; Rf (hexane/ethyl acetate 8/2)¼
0.78; dH (300 MHz) 0.05 [9H, s, Si(CH3)3], 0.78 (3H, t,
J¼7.2, CH2CH3), 2.23 (2H, q, J¼7.2, CH2), 7.15–7.33
(10H, m, 10ꢃArH); dC (75 MHz) ꢁ1.0 [Si(CH3)3], 9.0
(CH2CH3), 28.4 (CH2), 45.1 (CSi), 124.7, 127.5, 129.7
(ArCH), 145.7 (ArC); m/z 268 (M+, 14%), 240 (11), 195
(22), 194 (80), 193 (11), 165 (16), 135 (29), 115 (12), 91
(16), 73 (100); HRMS: M+, found 268.1687, C18H24Si
requires 268.1647.
acetate 8/2)¼0.42; n (film) 3454 (OH), 3056 (]CH) cmꢁ1
;
dH (400 MHz) 0.65 [9H, s, C(CH3)3], 0.69 [9H, s,
C(CH3)3], 1.01–1.09 (2H, m, CH2CH), 1.35 (1H, d, J¼5.5,
CH2CHOH), 1.73–1.81 (1H, m, CCH2), 2.16 (1H, d,
J¼4.1, Ph2CCHOH), 2.85–2.88 (1H, m, CH2CH), 2.93–
3.01 (1H, m, CCH2), 4.22 (1H, d, J¼4.1, Ph2CCH), 7.16–
7.56 (10H, m, 10ꢃArH); dC (100 MHz) 25.4 (CH3), 27.5
(CH2CH), 28.4 (CH3), 34.8, 36.6 [C(CH3)3], 37.0 (CCH2),
57.3 (CCH2), 80.8 (CH2CH), 83.2 (Ph2CCH), 126.0, 126.4,
127.4, 128.1, 128.5, 130.7 (ArCH), 141.1, 146.4 (ArC); m/z
293 [M+ꢁH2OꢁC(CH3)3, 2%], 193 (23), 181 (16), 180
(100), 179 (11), 165 (15); HRMS: M+ꢁ2ꢃH2OꢁC(CH3)3,
found 275.1856, C21H23 requires 275.1800.
4.4.2. 1,1-Diphenyl-1,3-bis(trimethylsilyl)-propane (15a).
Colourless oil, 129 mg; tR¼16.0 min; Rf (hexane/ethyl ace-
tate 8/2)¼0.83; n (film) 3056 (]CH) cmꢁ1; dH (300 MHz)
0.00 [9H, s, Si(CH3)3], 0.05 [9H, s, Si(CH3)3], 0.30–0.37
(2H, m, CH2Si), 2.14–2.20 (2H, m, CCH2), 7.15–7.32
(10H, m, 10ꢃArH); dC (75 MHz) ꢁ1.8, ꢁ0.9 [Si(CH3)3],
10.4 (CH2Si), 29.9 (CCH2), 46.0 (CSi), 124.7, 127.5,
129.7 (ArCH), 145.7 (ArC); m/z 340 (M+, 16%), 267 (15),
266 (53), 252 (25), 224 (35), 135 (22), 73 (100); HRMS:
M+, found 340.2063, C21H32Si2 requires 340.2043.
4.4.7. 1,2,2-Triphenyl-1-butanol (13d). Colourless oil,
149 mg; tR¼19.3 min; Rf (hexane/ethyl acetate 8/2)¼0.50;
n (film) 3558, 3455 (OH), 3056 (]CH) cmꢁ1; dH
(400 MHz) 0.67 (3H, t, J¼7.3, CH3), 1.80–1.87 (1H, m,
CH2), 1.90–1.97 (1H, m, CH2), 2.16 (1H, d, J¼4.6, OH),
5.61 (1H, d, J¼4.6, CH), 6.64 (2H, d, J¼7.5, 2ꢃArH),
7.05–7.36 (13H, m, 13ꢃArH); dC (100 MHz) 9.2 (CH3),
30.9 (CH2), 56.9 (CCH2), 77.0 (CH), 126.0, 126.4, 126.9,
127.1, 127.5, 127.8, 128.1, 129.3, 130.8 (ArCH), 140.6,
141.6, 144.9 (ArC); m/z 284 (M+ꢁH2O, 2%), 197 (12), 196
(80), 195 (100), 179 (10), 178 (13), 167 (57), 165 (27), 117
(30), 115 (21), 107 (15), 91 (40), 79 (12), 77 (13); HRMS:
M+ꢁH2O, found 284.1532, C22H20 requires 284.1565.
4.4.3. 1,1-Diphenylpropyl(dimethyl)phenylsilane (13b).
Colourless oil, 52 mg; tR¼18.7 min; Rf (hexane/ethyl ace-
tate 8/2)¼0.77; n (film) 3052 (]CH) cmꢁ1; dH (300 MHz)
0.29 [6H, s, Si(CH3)2], 0.65 (3H, t, J¼7.2, CH2CH3), 2.24
(2H, q, J¼7.2, CH2), 7.09–7.36 (15H, m, 15ꢃArH); dC
(75 MHz) ꢁ2.9 [Si(CH3)2], 8.7 (CH2CH3), 28.6 (CH2),
45.8 (CCH2), 124.9, 127.2, 127.4, 127.7, 128.7, 129.9,
133.0, 135.0 (ArCH), 138.2, 144.6 (ArC); m/z 330 (M+,
4%), 194 (30), 136 (14), 135 (100); HRMS: M+, found
330.1805, C23H26Si requires 330.1804.
4.4.8. 2-Methyl-3,3-diphenyl-2-pentanol (13e). Colourless
oil, 150 mg; tR¼15.7 min; Rf (hexane/ethyl acetate 8/2)¼
; dH
0.34; n (film) 3480 (OH), 3055 (]CH) cmꢁ1
(300 MHz) 0.67 (3H, t, J¼7.2, CH2CH3), 1.24 [6H, s,
C(CH3)2], 2.34 (2H, q, J¼7.3, CH2), 7.17–7.29 (6H, m,
6ꢃArH), 7.46–7.49 (4H, d, J¼7.2, 4ꢃArH); dC (75 MHz)
10.1 (CH2CH3), 27.5 (CH2), 28.5 [C(CH3)2], 59.7 (CCH2),
77.0 (COH), 125.7, 126.9, 131.2 (ArCH), 144.2 (ArC); m/z
236 (M+ꢁH2O, 2%), 196 (47), 168 (14), 167 (100), 165
(20), 117 (11), 115 (12), 91 (18), 59 (19).25
4.4.4. 1,1-Diphenyl-1,3-bis(dimethylphenylsilyl)-pro-
pane (15b). Colourless oil, 261 mg; tR¼28.5 min; Rf (hex-
ane/ethyl acetate 8/2)¼0.71; n (film) 3067, 3051 (]CH)
cmꢁ1; dH (300 MHz) 0.19 [6H, s, Si(CH3)2], 0.23 [6H, s,
Si(CH3)2], 0.40–0.50 (2H, m, CH2Si), 2.12–2.19 (2H, m,
CCH2), 7.01–7.43 (20H, m, 20ꢃArH); dC (75 MHz) ꢁ3.3,
ꢁ2.9 (CH3), 9.1 (CH2Si), 30.3 (CCH2), 46.7 (CCH2),
124.8, 127.2, 127.4, 127.7, 128.7, 128.8, 129.9, 133.6,
134.9 (ArCH), 138.1, 139.0, 144.5 (ArC); m/z 464 (M+,
1%), 328 (15), 314 (13), 253 (11), 252 (45), 136 (14), 135
(100); HRMS: M+, found 464.2365, C31H36Si2 requires
464.2356.
4.4.9. 2-Methyl-5,5-diphenyl-2-pentanol (14e). Colour-
less oil, 16 mg; tR¼15.7 min; Rf (hexane/ethyl acetate
8/2)¼0.23; n (film) 3391 (OH), 3060 (]CH) cmꢁ1; dH
(300 MHz) 1.20 (6H, s, 2ꢃCH3), 1.40–1.47 (2H, m,
CH2C), 2.09–2.17 (2H, m, CHCH2), 3.85 (1H, t, J¼7.7,
CH), 7.14–7.31 (10H, m, 10ꢃArH); dC (75 MHz) 29.2
(CH3), 30.3 (CHCH2), 42.3 (CH2C), 51.7 (CH), 70.9
(COH), 126.1, 127.8, 128.4 (ArCH), 145.0 (ArC); m/z 236
(M+ꢁH2O, 4%), 181 (15), 180 (100), 179 (10), 168 (13),
167 (89), 166 (14), 165 (43), 152 (17).26
4.4.5. 2,2-Dimethyl-4,4-diphenyl-3-hexanol (13c). Colour-
less oil, 160 mg; tR¼16.7 min; Rf (hexane/ethyl acetate
8/2)¼0.61; n (film) 3585 (OH), 3057 (]CH) cmꢁ1; dH
(400 MHz) 0.61 (3H, dd, J¼7.3, 7.1, CH2CH3), 0.77 [9H,
s, C(CH3)3], 2.02 (1H, dt, J¼14.2, 7.1, CH2), 2.13 (1H,
d, J¼4.4, OH), 2.60 (1H, dt, J¼14.2, 7.3, CH2), 4.29 (1H,
d, J¼4.4, CH), 7.24–7.41 (8H, m, 8ꢃArH), 7.55–7.57
(2H, m, 2ꢃArH); dC (100 MHz) 10.1 (CH2CH3), 28.4
[C(CH3)3], 31.4 (CH2), 37.0 [C(CH3)3], 57.6 (CCH2), 82.6
4.4.10. 3-Ethyl-6,6-diphenyl-3-hexanol (14f). Colour-
less oil, 148 mg; tR¼17.2 min; Rf (hexane/ethyl acetate
8/2)¼0.34; n (film) 3441 (OH), 3060 (]CH) cmꢁ1; dH
(300 MHz), 0.78 (6H, t, J¼7.5, CH3), 1.34–1.47 (6H, m,
CH2CH2C, 2ꢃCH2CH3), 2.01–2.09 (2H, m, CHCH2), 3.82

C. Goꢀmez et al. / Tetrahedron 63 (2007) 4655–4662
4661
ꢀ
ꢀ
Ramon, D. J. Lat. J. Chem. 2002, 79–92; (e) Ramon, D. J.;
Yus, M. Rev. Cubana Quim. 2002, 14, 75–115; (f) Yus, M.
The Chemistry of Organolithium Compounds; Rappoport, Z.,
Marek, I., Eds.; J. Wiley & Sons: Chichester, UK, 2004; Vol.
1, Part 2, Chapter 11; For mechanistic studies, see: (g) Yus,
M.; Herrera, R. P.; Guijarro, A. Tetrahedron Lett. 2001, 42,
3455–3458; (h) Yus, M.; Herrera, R. P.; Guijarro, A. Chem.—
Eur. J. 2002, 8, 2574–2584; (i) Yus, M.; Herrera, R. P.;
Guijarro, A. Tetrahedron Lett. 2003, 44, 1309–1312; (j) Yus,
M.; Herrera, R. P.; Guijarro, A. Tetrahedron Lett. 2003, 44,
1313–1316; (k) Yus, M.; Herrera, R. P.; Guijarro, A.
Tetrahedron Lett. 2003, 44, 5025–5027; For a polymer sup-
ported arene-catalysed version of this reaction, see: (l)
(1H, t, J¼7.6, CH), 7.12–7.30 (10H, m, 10ꢃArH); dC
(75 MHz) 7.7 (CH3), 29.5 (CHCH2), 30.9 (CH2CH3), 36.6
(CH2CH2C), 51.9 (CH), 74.6 (COH), 126.1, 127.7, 128.4
(ArCH), 145.0 (ArC); m/z 264 (M+ꢁH2O, 3%), 181 (16),
180 (100), 175 (11), 167 (41), 165 (28), 152 (10), 57 (13);
HRMS: M+ꢁH2O, found 264.1877, C20H24 requires
264.1878.
4.4.11. 1-(1,1-Diphenylpropyl)-1-cyclohexanol (13g).
Colourless oil, 130 mg; tR¼18.6 min; Rf (hexane/ethyl ace-
tate 8/2)¼0.53; n (film) 3578 (OH), 3054 (]CH) cmꢁ1
;
dH (300 MHz) 0.62 (3H, t, J¼7.3, CH3), 0.82–1.93 (10H,
m, 5ꢃring CH2), 2.32 (2H, q, J¼7.3, CH2CH3), 7.17–7.28
(6H, m, 6ꢃArH), 7.48 (4H, d, J¼7.3, 2ꢃArH); dC
(75 MHz) 10.0 (CH3), 21.9, 25.3, 26.9, 33.2 (3ꢃring CH2,
CH2CH3), 60.6 (CCH2CH3), 77.5 (COH), 125.6, 126.8,
131.5 (ArCH), 143.7 (ArC); m/z 294 (M+, 1%), 197 (12),
196 (74), 168 (14), 167 (100), 165 (20), 117 (10), 115
(11), 99 (40), 91 (16), 81 (24); HRMS: M+ꢁH2O, found
276.1861, C21H24 requires 276.1878.
ꢀ
Gomez, C.; Ruiz, S.; Yus, M. Tetrahedron Lett. 1998, 39,
1397–1400; (m) Gomez, C.; Ruiz, S.; Yus, M. Tetrahedron
ꢀ
1999, 55, 7017–7026; (n) Yus, M.; Candela, P.; Gomez, C.
Tetrahedron 2002, 58, 6207–6210; (o) Alonso, F.; Gomez,
C.; Candela, P.; Yus, M. Adv. Synth. Catal. 2003, 345, 275–
ꢀ
279; (p) Candela, P.; Gomez, C.; Yus, M. Russ. J. Org. Chem.
2004, 40, 795–801.
ꢀ
ꢀ
6. For recent reviews on polylithio intermediates, see: (a)
Foubelo, F.; Yus, M. Trends Org. Chem. 1998, 7, 1–26;
(b) Foubelo, F.; Yus, M. Curr. Org. Chem. 2005, 9, 459–490;
(c) For a general overview, see also Ref. 2.
7. The excess of lithium powder is necessary when the scale of the
reaction is only 1 mmol in order to avoid the loss of the metal,
which is floating on the reaction mixture and on the wall of the
flask. Actually, for reactions performed at 5–10 mmol scale,
a 1/2.5 substrate/lithium powder ratio is enough to be used in
the arene-catalysed lithiation: Yus, M.; Moreno, B.; Foubelo,
F. Synthesis 2004, 1115–1118.
8. For a general account on structure, reactivity and selectivity of
allylic organoalkali reagents, see: (a) Schlosser, M.
Organometallics in Synthesis. A Manual; Schlosser, M., Ed.;
J. Wiley & Sons: Chichester, UK, 1994; Chapters 1.2 and
1.3; For some reviews on transition-metal-catalysed allylic sub-
stitution, see: (b) Trost, B. M.; Van Vranken, D. L. Chem. Rev.
1996, 96, 395–422; (c) Trost, B. M.; Crawley, M. L. Chem. Rev.
2003, 103, 2921–2943.
4.4.12. 3-(tert-Butyl)-2,2-dimethyl-6,6-diphenyl-3-hexa-
nol (14h). Colourless oil, 169 mg; tR¼19.6 min; Rf (hex-
ane/ethyl acetate 8/2)¼0.61; n (film) 3626 (OH), 3060
(]CH) cmꢁ1; dH (300 MHz) 0.87 (18H, s, 6ꢃCH3), 1.45–
1.51 (2H, m, CH2C), 2.01–2.10 (2H, m, CHCH2), 3.72
(1H, t, J¼7.6, CH), 7.06–7.08 (2H, m, 2ꢃArH), 7.16–7.19
(8H, m, 8ꢃArH); dC (75 MHz) 28.5 (CH3), 31.7, 32.4
(CHCH2, CH2C), 42.5 [C(CH3)3], 52.3 (CH), 79.6 (COH),
126.0, 127.8, 128.3 (ArCH), 145.2 (ArC); m/z 338 (M+,
1%), 282 (12), 281 (55), 204 (13), 203 (81), 194 (15), 193
(84), 181 (22), 180 (100), 168 (10), 167 (56), 166 (18),
165 (46), 152 (18), 143 (11), 118 (10), 117 (94), 115 (12),
91 (13), 87 (22), 57 (51); HRMS: M+ꢁC(CH3)3, found
281.1882, C20H25O requires 281.1905.
Acknowledgements
9. The main by-product characterised by tandem GC–MS was in
all cases propylbenzene, resulting from a reduction of the ‘re-
duced’ product propen-1-ylbenzene (11 with X¼H, coming
from a g-proton abstraction by the allylic intermediate 5) by
dissolving metals, probably in the work-up (addition of water
in the presence of an excess of lithium powder).
This work was generously supported by the Spanish Minis-
ꢀ
and the Generalitat Valenciana (grant no. GRUPOS05/
052). V.J.L. thanks the University of Alicante for a fellow-
ship. We also thank Medalchemy S.L. and Chemetall
GmbH for gifts of chemicals.
terio de Educacion y Ciencia (grant no. CTQ2004-01261)
10. For a review on the addition of allylic organometallic reagents
to carbonyl compounds, see: Denmark, S. E.; Fu, J. Chem. Rev.
2003, 103, 2763–2793.
References and notes
11. Similar results have been obtained in our group for other
allyllithium derivatives generated by different ways and
chlorosilanes or carbonyl compounds as electrophiles: (a)
1. Smith, M. B.; March, J. Advanced Organic Chemistry, 5th ed.;
Wiley-Interscience: New York, NY, 2001; pp 180–184.
2. Maercker, A. Lithium Chemistry: A Theoretical and Experi-
mental Overview; Sapse, A.-M., Schleyer, P. v. R., Eds.;
Wiley-Interscience: New York, NY, 1995; pp 477–577.
3. For a study on the formation of a radical-anion intermediate
from arylcyclopropanes in the presence of sodium–potassium
in THF, see: Boche, G.; Wintermayr, H. Angew. Chem., Int.
Ed. Engl. 1981, 20, 874–875.
ꢀ
ꢀ
Alonso, E.; Guijarro, D.; Martınez, P.; Ramon, D. J.; Yus,
M. Tetrahedron 1999, 55, 11027–11038; (b) Yus, M.;
ꢀ
Martınez, P.; Guijarro, D. Synth. Commun. 2003, 33, 2365–
2376.
12. See, for example: (a) Azzena, U.; Dettori, F.; Sforazzini, G.;
Yus, M.; Foubelo, F. Tetrahedron 2006, 62, 1557–1563; (b)
Yang, A.; Butela, H.; Deng, K.; Doubleday, D.; Cohen, T.
Tetrahedron 2006, 62, 6526–6535.
13. This compound was prepared by a modification of the proce-
dure described in the literature (Huang, J.-H.; Lee, T.-Y.;
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13e and 14e, so the capture of a proton took place before the
final hydrolysis.
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