Desilylation procedure via a naphthalene-catalysed lithiation reaction

Article abstract of DOI:10.1016/j.tet.2005.03.145

The reaction of silyl protected alcohols, amines and thiols with lithium powder and a catalytic amount of naphthalene, in THF, at 0°C led, after hydrolysis, to the recovery of the free alcohols, amines and thiols in very good yields. At least a phenyl group was required in the silyl protecting group for the success of the reaction. Some polyfunctionalised starting materials have successfully been deprotected. The stereochemical outcome of the deprotection of a silylated chiral secondary alcohol has also been studied and no racemization was observed. The process has shown to be a good alternative to the acid-catalysed desilylation procedures, the latter being not useful for the deprotection of some silylated tertiary alcohols.

Full text of DOI:10.1016/j.tet.2005.03.145

Tetrahedron 61 (2005) 6908–6915
Desilylation procedure via a naphthalene-catalysed
lithiation reaction
*
Cherif Behloul, David Guijarro and Miguel Yus
´ ´ ´ ´
Departamento de Quımica Organica, Facultad de Ciencias and Instituto de Sıntesis Organica (ISO), Universidad de Alicante, Apdo. 99,
E-03080 Alicante, Spain
Received 26 January 2005; revised 3 March 2005; accepted 31 March 2005
Abstract—The reaction of silyl protected alcohols, amines and thiols with lithium powder and a catalytic amount of naphthalene, in THF, at
0 8C led, after hydrolysis, to the recovery of the free alcohols, amines and thiols in very good yields. At least a phenyl group was required in
the silyl protecting group for the success of the reaction. Some polyfunctionalised starting materials have successfully been deprotected. The
stereochemical outcome of the deprotection of a silylated chiral secondary alcohol has also been studied and no racemization was observed.
The process has shown to be a good alternative to the acid-catalysed desilylation procedures, the latter being not useful for the deprotection of
some silylated tertiary alcohols.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
organolithium compounds11 by chlorine–lithium exchange
or by ring opening of heterocycles.12 The reductive cleavage
of several allylic and benzylic carbon-heteroatom bonds has
led to a method for removal of some protecting groups for
alcohols, amines and thioethers.13 We have recently
described the reductive detritylation of trityl ethers14 and
N-tritylamines15 by a naphthalene-catalysed lithiation
process. In a previous study, we described one example in
which the dimethylphenylsilyl group could be removed
from a protected aliphatic alcohol in a naphthalene-
catalysed lithiation reaction.13 We decided to investigate
in more detail the scope of this process and in this paper we
report the application of this lithiation methodology to the
removal of different silyl groups from several protected
alcohols, amines and thiols under mild reaction conditions.
The silyl group is one of the most popular protecting groups
for alcohols1 and, to a lesser extent, for amines1b,2 and
thiols.3 This is due to the fact that its introduction and
subsequent removal can be modulated by the proper choice
of the substituents on the silicon atom.1,4 The deprotection
of the silyl group can be carried out under mild acidic
conditions or by treatment with fluoride anion, although
some other desilylation procedures have been published
which involve basic reaction conditions or redox processes.1
Some of these processes gave some incompatibility
problems5 with other functional groups present in poly-
functionalised molecules or showed lack of chemo-
selectivity when the selective deprotection4 of molecules
with several silyl groups was tested.5b,6 Palladium catalysts
have also been applied to the removal of several silyl
protecting groups under hydrogenolysis conditions.7
2. Results and discussion
In the last few years, we have been using an arene-catalysed
lithiation8,9 to prepare organolithium compounds under very
mild reaction conditions. The use of an excess of lithium
powder and a catalytic amount of an arene [mainly
naphthalene or 4,40-di-tert-butylbiphenyl (DTBB)] allowed
us to generate simple organolithium compounds starting
from non-halogenated materials,10 and functionalised
All silylated substrates 1–3 were prepared from com-
mercially available alcohols (for 1), amines (for 2) or thiols
(for 3) and the corresponding silyl chlorides under basic
reaction conditions, except for compound 3b for which the
general procedure was unsuccessful, but it could be
prepared under Lewis acid catalysis. Some starting
materials, especially the ones bearing a dimethyl(phenyl)-
silyl group, were found to be relatively unstable, decom-
posing upon storage for some months at room temperature.
The stability of the silylated substrates increased with the
number of phenyl groups on the silicon atom. No
Keywords: Lithium; Naphthalene; Silyl; Deprotection; Desilylation;
Alcohols; Amines; Thiols.
*
Corresponding author. Tel.: C34 965903548; fax: C34 965903549;
e-mail: yus@ua.es
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.03.145

C. Behloul et al. / Tetrahedron 61 (2005) 6908–6915
6909
(Table 1, entry 4, footnote b). We assume that the reduction
in the reaction rate is due to the steric hindrance caused by
the bulky tert-butyl group. It was found that at least one
phenyl group on the silicon atom was necessary for the
success of the desilylation process. The reaction failed when
trimethylsilyl-protected 1-decanol was used as substrate, the
starting material being quantitatively recovered after 3 days
at room temperature.
Scheme 1. Reagents and conditions: (i) Li, C10H8 (8 mol%), THF, 0 8C;
(ii) H2O.
decomposition was observed in the triphenylsilyl deriva-
tives after storing them for one year at room temperature.
Next, the versatility of our method concerning the silylated
substrate was studied. Compounds 1b and 1c, derived from
secondary alcohols, gave the corresponding desilylated
products in very good yields (Scheme 1 and Table 1, entries
5–7). Optically pure (R)-2-octanol was also protected with
the dimethyl(phenyl)silyl group [(R)-1c (Table 1, entry 7)]
and submitted to our lithiation reaction in order to check if
there was any racemization during the process. Product (R)-
4c was esterified with optically pure (R)-a-methoxyphenyl-
acetic acid and no loss of enantiomeric purity was observed
by comparison of the 13C NMR spectra of the obtained ester
and the esters that were prepared from the same acid and
commercially available racemic 2-octanol and (R)-2-
octanol. Thus, the stereochemistry of the chiral alcohol
was preserved during the whole process. The triphenylsilyl
group of the protected tertiary alcohol 1d could also be
removed in almost quantitative yield (Table 1, entry 8). It is
worth noting that the attempted deprotection of compound
1d by conventional methods was not satisfactory: whereas
substrate 1d was recovered unchanged after treatment with
1 M hydrochloric acid for 24 h at room temperature, the
1-Decanol was used as a model starting material and it was
converted into silyl ethers 1aa–1ad (Scheme 1, Table 1,
entries 1–4) possessing different substituents on the silicon
atom. The reaction of compounds 1aa–1ac with an excess of
lithium powder (1:9 molar ratio) and a catalytic amount of
naphthalene (1:0.16 molar ratio; 8 mol%) in THF at 0 8C
gave, after hydrolysis with water, the expected primary
alcohol 4a in quantitative yield (Scheme 1 and Table 1,
entries 1–3). Compound 1ad, bearing a bulky tert-butyl and
two phenyl groups as substituents at the silicon atom, did
not react under the same reaction conditions, the unaltered
starting material 1ad being recovered after 8 h at 0 8C.
However, the desilylation of 1ad took place when the
reaction was stirred at room temperature for 3 days, giving a
58% yield of 1-decanol 4a and some unreacted starting
material.16 The yield of 4a could be improved to 85% by
running the reaction for 4 days at room temperature using
DTBB as an electron carrier instead of naphthalene
Table 1. Desilylation of compounds 1–3 via a naphthalene-catalysed lithiation: preparation of compounds 4–6
Entry
Substrate
Product
Yield (%)a
No.
X
R1
R2
R3
Time (h)
No.
1
2
3
4
5
6
7
8
1aa
1ab
1ac
1ad
1b
O
O
O
O
O
O
O
O
O
O
O
O
O
Me(CH2)9
Me(CH2)9
Me(CH2)9
Me(CH2)9
c-C6H11
Me
Me
Ph
Me
Ph
Ph
Ph
Me
Me
Me
Ph
Ph
Ph
3.5
2.0
4.5
96.0
5.0
4.0
3.5
5.0
1.0
1.0
3.0
3.0
6.0
3.0
5.0
3.0
5.0
5.0
1.5
5.0
4a
4a
4a
4a
4b
4c
(R)-1c
4d
4e
O99
O99
O99
85b
O99
81c
77c
98
But
Me
Me
Me
Ph
1c
Me(CH2)5CH(Me)
Me(CH2)5CH(Me)
Pri(CH2)3C(Me)(Et)
2,4,6-Me3C6H2
HO(CH2)9
(R)-1c
1d
1e
9
Ph
Ph
Me
But
Ph
94
10
11
12
13
14
15
16
17
18
19
20
1f
4f
4f
98d
79
1ga
1gb
1h
2a
2b
2c
2d
3a
3b
Ph3SiO(CH2)9
Ph3SiO(CH2)9
Ph3SiN(Me)(CH2)6
Me(CH2)7
Me
Ph
4ge
4hf
5a
63c
63g
97
Ph
Me
Me(CH2)7N
h
—
MeN
MeO(CH2)2N
Me
h
—
h
h
—
—
Ph
5bi
5c
89
82
97
84
51
48
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
MeO(CH2)2
Me(CH2)9
c-C6H11
Ph
5d
6a
6b
6c
S
S
S
3c
a Yield determined by quantitative GLC, using commercially available compound 4–6 and n-dodecane (internal standard) in the determination of response
factors.
b DTBB was used as an electron carrier instead of naphthalene and the reaction was run at 20 8C.
c Isolated yield after column chromatography (silica gel, hexane/ethyl acetate) based on the starting material 1. All isolated compounds 4 were R95% pure
(GLC and/or 300 MHz 1H NMR).
d Compound 1f was deprotonated with n-BuLi before performing the naphthalene-catalysed lithiation step.
e 4gZ9-[tert-butyl(diphenyl)silyloxy]-1-nonanol.
f
4hZ6-(methylamino)-1-hexanol.
g Yield determined by quantitative GLC, using commercially available compound 4h and n-hexadecane (internal standard) in the determination of response
factors.
h 2bZ4-benzyl-N-(triphenylsilyl)piperidine.
i
5bZ4-benzylpiperidine.

6910
C. Behloul et al. / Tetrahedron 61 (2005) 6908–6915
reaction between 1d and tetrabutylammonium fluoride gave
only a 34% yield of alcohol 4d after 6 h at room temperature
(compare with entry 8 in Table 1). Triphenylsilyl-protected
phenol 1e was also effectively desilylated, affording phenol
4e in very good yield (Table 1, entry 9). Hydroxy-
functionalised silylated alcohol 1f gave the expected 1,9-
nonanediol 4f in almost quantitative yield after submitting
its lithium alkoxide to the naphthalene-catalysed lithiation
reaction for 1 h (Table 1, entry 10).
In all cases, the corresponding silanes were obtained
(O90%) as by-products which could easily be separated
from the desired products by column chromatography. The
formation of these silanes suggests that a possible reaction
mechanism would involve reductive cleavage of the
silicon–heteroatom bond to generate lithium alkoxides
(from 1), amides (from 2) or thiolates (from 3) and the
corresponding silyl radicals, which would be further,
reduced to the silyllithium derivatives by reaction with
lithium. Protonation of the silyllithium species in the
hydrolysis step would afford the obtained silanes.
Our methodology was successfully applied to the desilyl-
ation of protected secondary amines and thiols (Scheme 1
and Table 1, entries 14–20). The dimethyl(phenyl)silyl
and the triphenylsilyl groups could easily be removed from
an acyclic and a cyclic protected secondary amine,
respectively, in excellent yields (Table 1, entries 14 and
15). N-Methylaniline 5c was obtained in a very good yield
in the lithiation of substrate 2c (Table 1, entry 16).
Dimethoxy functionalised silylated amine 2d afforded the
free amine 5d in almost quantitative yield (Table 1, entry
17). We also tried the desilylation of protected primary
amines but it failed. Octylamine and cyclooctylamine were
protected with dimethyl(phenyl)silyl and triphenylsilyl
groups and the removal of these groups was attempted
following the same procedure previously used by us in the
deprotection of tritylated primary amines,15 consisting in
deprotonation with n-butyllithium and treatment with
trimethylsilyl chloride before performing the lithiation
step. Unfortunately, the reactions did not work as desired,
the unchanged starting materials being quantitatively
recovered. Concerning sulfur-containing substrates, silyl
thioethers 3a–3c, derived from primary, secondary and
aromatic thiols, could also be desilylated in moderate to
good yields (Table 1, entries 18–20). The moderate yields
obtained with cyclohexanethiol 3b and thiophenol 3c could
be attributed to some oxidation of the obtained thiols to the
corresponding disulfides during the work-up, since, the
latter were detected in the crude reaction mixtures
(GC–MS).
Allylic and benzylic substrates were tested too, but with
unsatisfactory results. Benzyl alcohol was converted into
the corresponding dimethyl(phenyl)silyl and triphenylsilyl
ethers and the latter were treated with lithium and a catalytic
amount of naphthalene at 0 8C. Toluene and the correspond-
ing silanol were the only reaction products detected
(GC–MS), indicating that cleavage of the carbon–oxygen
bond instead of the silicon–oxygen bond had taken place.
The same selectivity for the cleavage of the carbon–oxygen
bond was observed in the lithiation of the geranyl
triphenylsilyl ether. A similar carbon–oxygen bond
cleavage had been found by us with trimethylsilyl protected
allylic and benzylic alcohols.17 Toluene was also obtained
in the lithiation of N-methyl-N-(triphenylsilyl)benzylamine
and benzyl triphenylsilyl sulfide.
3. Conclusion
In conclusion, we have reported here, a very efficient
procedure to remove several silyl protecting groups from
silylated alcohols, amines and thiols under mild reaction
conditions. The methodology is applicable to aliphatic and
aromatic derivatives, but not to allylic or benzylic ones. This
desilylation procedure works very well even for branched
alcohols and thiols, being superior to the conventional
methods for the deprotection of tertiary alcohols. No
racemization was observed when the deprotection of a
silylated optically pure alcohol was performed. Concerning
amines, the process is limited to secondary ones, being not
useful for the deprotection of silylated primary amines. This
method represents a good alternative to the common
desilylation procedures, which require acidic reaction
conditions or treatment with fluoride anion.
We also studied the possible chemoselectivity of our
methodology by performing the lithiation of the disilylated
starting materials 1g and 1h (Scheme 1 and Table 1, entries
11–13). No selectivity was observed when unsymmetrically
protected 1,9-nonanediol 1ga, bearing a dimethyl(phenyl)-
silyl and a triphenylsilyl group, was used as substrate: the
diol 4f was obtained in good yield (Table 1, entry 11). The
result was the same when the reaction was repeated at
K78 8C. The same lack of selectivity was found when two
different functional groups were protected with the same
silyl group. 6-Methylamino-1-hexanol was protected both at
nitrogen and at oxygen with the triphenylsilyl group. When
the obtained compound 1h was submitted to the naphtha-
lene-catalysed lithiation reaction, the free amino alcohol 4h
was recovered in good yield (Table 1, entry 13). However,
when compound 1gb bearing tert-butyl(diphenyl)silyloxy
and triphenylsilyloxy groups was tested, only monodesilyl-
ation took place, the triphenylsilyl group being the only one
that was removed when the reaction was performed at 0 8C
(Table 1, entry 12). We were expecting this last result,
according to the different reaction rates shown by
compounds 1aa and 1ad (compare entries 1 and 4 in
Table 1).
4. Experimental
4.1. General
For general information, see Ref. 15. All reagents used for
the synthesis of silylated substrates 1–3 and naphthalene
were commercially available (Acros, Aldrich) and were
used without further, purification, except for triethylamine,
which was refluxed for 1 h with phosphorus pentoxide and
distilled under Ar before use. Lithium powder was prepared
according to the procedure described in Ref. 18. Com-
mercially available n-butyllithium was titrated with a 1 M
solution of sec-butanol in xylene using 1,10-phenanthroline
as indicator.19 Commercially available anhydrous THF
(99.9%, water content %0.006%, Acros) and CH2Cl2

C. Behloul et al. / Tetrahedron 61 (2005) 6908–6915
6911
(O99.5%, water content %0.005%, Fluka) were used as
solvents in the reactions. All glassware was dried in an oven
at 100 8C and cooled to room temperature under vacuum
before use.
29.55, 29.6, 31.9, 32.5 [Me(CH2)8], 64.0 (CO), 127.8 (6C),
129.9 (3C), 134.5 (3C), 135.4 (6C) (ArC); m/z 416 (MC,
!1%), 340 (13), 339 (46), 338 (16), 261 (18), 260 (67), 253
(11), 200 (19), 199 (100), 190 (13), 184 (13), 183 (46), 182
(29), 181 (29), 176 (23), 155 (11), 123 (14).
4.2. Synthesis of the silylated alcohols 1a–1g, amines 2
and thiols 3a and 3c. General procedure
4.2.4. 1-[tert-Butyl(diphenyl)silyloxy]decane (1ad).22
Colourless oil; yield: 40%; Rf 0.92 (hexane/ethyl acetate:
9:1); n (film) 3070, 3049, 1603 (HC]C), 1110 (SiO),
1088 cmK1 (CO); dH 0.88 (3H, t, JZ6.9 Hz, MeCH2), 1.04
(9H, s, 3!MeC), 1.16–1.40 [14H, m, Me(CH2)7], 1.49–
1.62 (2H, m, CH2CO), 3.65 (2H, t, JZ6.6 Hz, CH2O), 7.30–
7.47, 7.59–7.73 (6H and 4H, respectively, 2m, ArH); dC
14.1 (MeCH2), 19.2 (CMe3), 26.9 (3C, 3!MeC), 22.7, 29.3,
29.4 (2C), 29.55, 29.6, 31.9, 32.6 [Me(CH2)8], 64.0 (CO),
127.5 (4C), 129.5 (2C), 134.3 (2C), 135.6 (4C) (ArC); m/z
396 (MC, !1%), 340 (33), 339 (100), 199 (21), 183 (11).
Alcohol 1, amine 2 or thiol 3 (5.0 mmol) was added to a
stirred solution of the corresponding silylating agent
[dimethyl(phenyl)silyl chloride, methyl(diphenyl)silyl
chloride, tert-butyl(diphenyl)silyl chloride or triphenylsilyl
chloride (see Scheme 1 and Table 1); 5.0 mmol], triethyl-
amine (1.3 mL, 8.8 mmol) and 4-(dimethylamino)pyridine
(92 mg, 0.4 mmol) in CH2Cl2 (10 mL) under Ar at 20 8C
and the resulting mixture was stirred overnight. The crude
reaction mixture was then adsorbed on basic aluminium
oxide, transferred to a short column of basic aluminium
oxide and eluted with hexane. Evaporation of the solvent
(15 Torr) afforded the expected silylated compounds 1a–1g,
2, 3a and 3c in pure form. The synthesis of compounds 1g
was performed in a two step sequence: after stirring
overnight the mixture of 1,9-nonanediol, triphenylsilyl
chloride, triethylamine and 4-(dimethylamino)pyridine in
the proportions indicated above, the same amount of
dimethyl(phenyl)silyl chloride (for 1ga) or tert-butyl-
(diphenyl)silyl chloride (for 1gb) were added and the
reaction was stirred overnight again. The corresponding
physical, spectroscopic and analytical data for compounds
1a–1g, 2, 3a and 3c follow.
4.2.5. [Dimethyl(phenyl)silyloxy]cyclohexane (1b).23
Colourless oil; yield: 62%; Rf 0.92 (hexane/ethyl acetate:
9:1); n (film) 3069, 3050, 1590 (HC]C), 1118 (SiO),
1088 cmK1 (CO); dH 0.38 (6H, s, 2!Me), 1.49–2.32 (10H,
m, 5!CH2), 3.99–4.13 (1H, m, CHO), 7.27–7.42, 7.51–
7.65 (3H and 2H, respectively, 2m, ArH); dC K1.0 (2C, 2!
Me), 24.3 (2C), 25.5, 35.8 (2C) (5!CH2), 71.3 (CO), 127.7
(2C), 129.4, 133.4 (2C), 138.7 (ArC); m/z (DIP) 219 (MCK
Me, 60%), 191 (16), 156 (30), 146 (26), 137 (100), 135 (40),
111 (14), 97 (20), 85 (16), 83 (24), 82 (12), 71 (25), 70 (18),
69 (23), 57 (34), 56 (13), 55 (24), 43 (49), 41 (17).
4.2.6. 2-[Dimethyl(phenyl)silyloxy]octane (1c).24 Colour-
less oil; yield: 97%; Rf 0.93 (hexane/ethyl acetate: 9:1); n
(film) 3069, 3050, 1591 (HC]C), 1118 (SiO), 1094 cmK1
(CO); dH 0.38 (6H, s, 2!MeSi), 0.87 (3H, t, JZ6.9 Hz,
MeCH2), 1.09 (3H, d, JZ6.9 Hz, MeCO), 1.10–1.52 [10H,
m, Me(CH2)5], 3.72–3.84 (1H, m, CHO), 7.31–7.43, 7.51–
7.64 (3H and 2H, respectively, 2m, ArH); dC K1.2, K1.1
(2!MeSi), 14.1 (MeCH2), 23.7 (MeCO), 22.6, 25.7, 29.3,
31.8, 39.5 (5!CH2), 69.0 (CO), 127.7 (2C), 129.4, 133.5
(2C), 138.5 (ArC); m/z 264 (MC, !1%), 249 (21), 168 (13),
179 (56), 138 (11), 137 (88), 136 (14), 135 (100), 75 (34).
4.2.1. 1-[Dimethyl(phenyl)silyloxy]decane (1aa). Colour-
less oil; yield: O99%; Rf 0.86 (hexane/ethyl acetate: 9:1) n
(film) 3082, 3057, 3029, 1596 (HC]C), 1115 (SiO),
1093 cmK1 (CO); dH 0.33 (6H, s, 2!MeSi), 0.88 (3H, t,
JZ6.7 Hz, MeCH2), 1.17–1.65 [16H, m, Me(CH2)8], 3.64
(2H, t, JZ6.6 Hz, CH2O), 7.29–7.43, 7.48–7.61 (3H and
2H, respectively, 2m, ArH); dC 0.8 (2C, 2!MeSi), 14.1
(MeCH2), 22.7, 25.7, 29.3, 29.4, 29.5, 29.6, 31.9, 32.8
[Me(CH2)8], 63.1 (CO), 127.7 (2C), 129.2, 133.0 (2C),
139.8 (ArC); m/z 277 (MCKMe, 100), 214 (16), 137 (62),
135 (34), 121 (12); HRMS: MC, found 292.2230.
C18H32OSi requires 292.2220.
4.2.7. (2R)-2-[Dimethyl(phenyl)silyloxy]octane [(R)-1c].
Colourless oil; yield: 96%; Rf 0.93 (hexane/ethyl acetate:
9:1); [a]2D0 K1.5G0.2 (c 1, CHCl3); n (film) 3069, 3050,
1591 (HC]C), 1118 (SiO), 1071 cmK1 (CO); dH 0.38 (6H,
s, 2!MeSi), 0.87 (3H, t, JZ6.9 Hz, MeCH2), 1.09 (3H, d,
JZ6.9 Hz, MeCO), 1.10–1.56 [10H, m, Me(CH2)5], 3.72–
3.85 (1H, m, CHO), 7.28–7.42, 7.50–7.66 (3H and 2H,
respectively, 2m, ArH); dC K1.2, K1.1 (2!MeSi), 14.1
(MeCH2), 23.7 (MeCO), 22.6, 25.7, 29.3, 31.8, 39.5
[Me(CH2)5], 69.0 (CO), 127.7 (2C), 129.4, 133.5 (2C),
138.5 (ArC); m/z 264 (MC, !1%), 249 (21), 168 (13), 179
(56), 138 (11), 137 (88), 136 (14), 135 (100), 75 (34);
HRMS: MC, found 264.1889. C16H28OSi requires
264.1909.
4.2.2. 1-[Methyl(diphenyl)silyloxy]decane (1ab).20
Colourless oil; yield: 99%; Rf 0.88 (hexane/ethyl acetate:
9:1); n (film) 3069, 3049, 1590 (HC]C), 1118 (SiO),
1094 cmK1 (CO); dH 0.63 (3H, s, MeSi), 0.88 (3H, t, JZ
6.7 Hz, MeCH2), 1.15–1.39 [14H, m, Me(CH2)7], 1.47–1.63
(2H, m, CH2CO), 3.68 (2H, t, JZ6.6 Hz, CH2O), 7.26–7.45,
7.51–7.69 (6H and 4H, respectively, 2m, ArH); dC K3.0
(MeSi), 14.1 (MeCH2), 22.7, 25.8, 29.3, 29.4, 29.55, 29.6,
31.9, 32.6 [Me(CH2)8], 63.6 (CO), 127.8 (4C), 129.7 (2C),
134.3 (4C), 136.5 (2C) (ArC); m/z 339 (MCKMe, !1%),
244 (22), 243 (100), 166 (13), 165 (81).
4.2.3. 1-(Triphenylsilyloxy)decane (1ac).21 Yellow solid;
yield: O99%; Rf 0.70 (hexane/ethyl acetate: 9:1); mp 28 8C
(hexane); n (KBr) 3067, 3038, 1588 (HC]C), 1117 (SiO),
1088 cmK1 (CO); dH 0.88 (3H, t, JZ6.9 Hz, Me), 1.19–1.40
[14H, m, Me(CH2)7], 1.50–1.65 (2H, m, CH2CO), 3.78 (2H,
t, JZ6.2 Hz, CH2O), 7.30–7.49, 7.61–7.63 (9H and 6H,
respectively, 2m, ArH); dC 14.1 (Me), 22.7, 25.7, 29.3 (2C),
4.2.8. 2,6-Dimethyl-6-(triphenylsilyloxy)octane (1d).
Colourless oil; yield:O99%; Rf 0.64 (hexane/ethyl acetate:
9:1); n (film) 3068, 3049, 1602 (HC]C), 1113 (SiO),
1064 cmK1 (CO); dH 0.76–0.93 (9H, m, 2!MeCH and
MeCH2), 1.15 (3H, s, MeC), 1.22–1.59 (9H, m, MeCH and
4!CH2), 7.29–7.44, 7.60–7.72 (9H and 6H, respectively,

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C. Behloul et al. / Tetrahedron 61 (2005) 6908–6915
2m, ArH); dC 8.8 (MeCH2), 21.9, 34.5, 39.4, 41.5 (4!CH2),
22.5, 22.6 (2!MeCH), 27.8 (MeC), 78.7 (CO), 127.5 (6C),
129.4 (3C), 135.5 (6C), 136.8 (3C) (ArC); m/z 401 (MC
KMe, !1%), 387 (25), 332 (12), 331 (43), 260 (25), 259
(100), 299 (15), 181 (12); HRMS: MCKMe, found
401.2298. C27H33OSi requires 401.2301.
(26), 211 (100), 199 (17), 188 (16), 181 (16); HRMS: MCK
But, found 599.2798. C39H43O2Si2 requires 599.2800.
4.2.13. N-[Dimethyl(phenyl)silyl]-N-octyl-1-octanamine
(2a). Colourless oil; yield:O99%; Rf 0.92 (hexane/ethyl
acetate: 9:1); n (film) 3069, 3055, 1590 (HC]C), 1255
(CN), 1119 cmK1 (SiN); dH 0.46 (6H, s, 2!MeSi), 0.88
(6H, t, JZ6.7 Hz, 2!MeCH2), 0.84–1.03, 1.06–1.11 [20H
and 4H, respectively, 2m, 2!Me(CH2)6], 2.53 (4H, t, JZ
7.4 Hz, 2!CH2N), 7.29–7.42, 7.50–7.65 (3H and 2H,
respectively, 2m, ArH); dC 0.1 (2C, 2!MeSi), 14.1 (2C,
2!MeCH2), 22.6 (2C), 27.3 (2C), 29.2 (2C), 29.5 (2C),
29.8 (2C), 31.8 (2C) [2!Me(CH2)6], 49.8 (2C, 2!CN),
127.7 (2C), 129.3, 133.0 (2C), 139.0 (ArC); m/z (DIP) 346
(MCKEt, 2%), 272 (16), 271 (63), 193 (38), 143 (17), 142
(100), 44 (32), 43 (31); HRMS: MCKC7H15, found
276.2187. C17H30NSi requires 276.2150.
4.2.9. 1,3,5-Trimethyl-2-(triphenylsilyloxy)benzene
(1e).21 Yellow solid; yield: 98%; Rf 0.63 (hexane/ethyl
acetate: 9:1); mp 98 8C (hexane); n (KBr) 3066, 3045, 1604
(HC]C), 1162 (CO), 1115 cmK1 (SiO); dH 2.17, 2.22 (3H
and 6H, respectively, 2s, 3!Me), 6.78 (2H, s, 2!ArH),
7.27–7.48, 7.56–7.66 (9H and 6H, respectively, 2m, 15!
ArH); dC 18.3 (2C), 20.4 (3!Me), 123.3 (2C), 127.7 (6C),
128.3 (2C), 129.0 (3C), 130.0 (3C), 130.7, 135.5 (6C), 149.9
(ArC); m/z 395 (MCC1, 27%), 394 (MC, 75), 260 (25), 259
(100), 181 (19), 105 (11).
4.2.14. 4-Benzyl-N-(triphenylsilyl)piperidine (2b). White
solid; yield: 58%; Rf 0.87 (hexane/ethyl acetate: 9:1); mp
82 8C (hexane); n (KBr) 3065, 3055, 3023, 1600 (HC]C),
1228 (CN), 1111 cmK1 (SiN); dH 0.92–1.23 (2H, m, 2!
CHHCN), 1.49–1.71 (3H, m, 2!CHHCN and CHCH2Ph),
2.32–2.57 (4H, m, CH2Ph and 2!CHHN), 2.84–3.00 (2H,
m, 2!CHHN), 7.05–7.54 (20H, ArH); dC 32.7 (2C, 2!
CH2CN), 38.0 (CHCH2), 43.5 (CH2Ph), 46.0 (2C, 2!CN),
125.8, 127.6 (6C), 127.7 (5C), 129.7 (2C), 135.1 (6C), 135.4
(3C), 140.3 (ArC); m/z (DIP) 433 (MC, !1%), 260 (17),
259 (72), 257 (19), 250 (27), 211 (100), 190 (14), 188 (17),
181 (15); HRMS: MC, found 433.2256. C30H31NSi requires
433.2226.
4.2.10. 9-(Triphenylsilyloxy)-1-nonanol (1f).25 Colourless
oil; yield: 25%; Rf 0.85 (hexane/ethyl acetate: 9:1); n (film)
3555 (OH), 3068, 3048, 3023, 1589 (HC]C), 1116 (SiO),
1094, 1061 cmK1 (CO); dH 1.12–1.69 [14H, m, (CH2)7CO],
3.57–3.69 (3H, m, CH2OSi and OH), 3.78 (2H, t, JZ6.6 Hz,
CH2OH), 7.32–7.50, 7.54–7.72 (9H and 6H, respectively,
2m, ArH); dC 25.7 (2C), 25.9, 29.2, 29.3, 32.5, 32.8
[(CH2)7CO], 63.1, 64.0 (2!CO), 127.8 (6C), 129.9 (3C),
135.0 (3C), 135.4 (6C) (ArC); m/z (DIP) 341 (MCKPh,
48%), 263 (11), 260 (19), 259 (88), 200 (18), 199 (100), 184
(16), 183 (14), 182 (10), 181 (23), 154 (10), 139 (28), 83
(12), 69 (22), 55 (10).
4.2.11. 1-[Dimethyl(phenyl)silyloxy]-9-(triphenylsilyl-
oxy)nonane (1ga). White solid; yield: 56%; Rf 0.73
(hexane/ethyl acetate: 9:1); mp 42 8C (hexane); n (KBr)
3069, 3050, 3023, 1589 (HC]C), 1117 (SiO), 1094 cmK1
(CO); dH 0.37 (6H, s, 2!Me), 1.11–1.38, 1.43–1.65 [10H
and 4H, respectively, 2m, (CH2)7CO], 3.57, 3.77 (2H each,
2t, JZ6.6 Hz each, 2!CH2O), 7.30–7.47, 7.51–7.68 (12H
and 8H, respectively, 2m, ArH); dC K1.8 (2C, 2!Me),
25.7, 25.75, 29.2, 29.3, 32.5 (2C), 32.6 [(CH2)7CO], 63.2,
64.0 (2!CO), 127.8 (6C), 129.5 (2C), 129.9 (4C), 133.4
(3C), 134.4 (2C), 135.4 (6C), 138.0 (ArC); m/z (DIP) 552
(MC, !1%), 397 (12), 336 (24), 335 (82), 319 (14), 317
(16), 253 (11), 274 (15), 273 (59), 272 (11), 260 (24), 259
(100), 255 (22), 230 (15), 199 (49), 197 (20), 195 (25), 183
(20), 182 (11), 181 (24), 154 (12), 137 (28), 135 (32), 104
(11), 91 (19), 83 (16), 69 (27), 55 (13). Anal. Calcd for
C35H44O2Si2: C, 76.03; H, 8.02. Found: C, 76.93; H, 8.18.
4.2.15. N-Methyl-N-(triphenylsilyl)aniline (2c). White
solid; yield: 95%; Rf 0.89 (hexane/ethyl acetate: 9:1); mp
112 8C (hexane); n (KBr) 3067, 3047, 3024, 1589 (HC]C),
1274 (CN), 1117 cmK1 (SiN); dH 3.00 (3H, s, Me), 6.68–
6.77, 6.84–6.92, 6.98–7.10, 7.30–7.44, 7.56–7.68 (1H, 2H,
2H, 9H and 6H, respectively, 5m, ArH); dC 37.1 (Me), 118.7
(2C), 118.8, 127.9 (6C), 128.2 (2C), 129.7 (3C), 134.3 (3C),
135.9 (6C), 150.3 (ArC); m/z 366 (MCC1, 25%), 365 (MC,
79), 260 (24), 259 (100), 181 (23), 105 (15); HRMS: MC,
found 365.1606. C25H23NSi requires 365.1600.
4.2.16. Bis(2-methoxyethyl)(triphenylsilyl)amine (2d).
Colourless oil; yield: 95%; Rf 0.80 (hexane/ethyl acetate:
9:1); n (film) 3068, 3048, 1589 (HC]C), 1259 (CN),
1111 cmK1 (SiN); dH 3.10–3.22 (10H, m, 2!Me and 2!
CH2N), 3.33 (4H, t, JZ6.9 Hz, 2!CH2O), 7.31–7.46,
7.58–7.69 (9H and 6H, respectively, 2m, ArH); dC 47.6 (2C,
2!CN), 58.5 (2C, 2!Me), 72.7 (2C, 2!CH2O), 127.7
(6C), 129.5 (3C), 135.1 (3C), 136.1 (6C) (ArC); m/z 391
(MC, !1%), 347 (27), 346 (90), 260 (25), 259 (100), 181
(17); HRMS: MC, found 391.1963. C24H29NO2Si requires
391.1968.
4.2.12. 1-[tert-Butyl(diphenyl)silyloxy]-9-(triphenylsilyl-
oxy)nonane (1gb). Colourless oil; yield: 73%; Rf 0.86
(hexane/ethyl acetate: 9:1); n (film) 3068, 3048, 1589
(HC]C), 1115 (SiO), 1064 cmK1 (CO); dH 1.04 (9H, s, 3!
Me), 1.12–1.39, 1.47–1.64 [10H and 4H, respectively, 2m,
(CH2)7CO], 3.65, 3.77 (2H each, 2t, JZ6.5, 6.6 Hz,
respectively, 2!CH2O), 7.33–7.55, 7.58–7.72 (15H and
10H, respectively, 2m, ArH); dC 19.2 (CMe3), 26.9 (3C, 3!
Me), 22.6, 22.7, 25.7, 29.25, 29.35, 31.6, 32.5 [(CH2)7CO],
64.0, 64.05 (2!CO), 127.5 (3C), 127.8 (6C), 129.5 (2C),
129.9 (4C), 134.2 (2C), 134.5 (3C), 135.4 (6C), 135.6 (4C)
(ArC); m/z (DIP) 656 (MC, 6%), 655 (11), 501 (20), 500
(45), 499 (83), 422 (10), 216 (18), 259 (68), 257 (20), 250
4.2.17. 1-(Triphenylsilylthio)decane (3a). White solid;
yield: 69%; Rf 0.88 (hexane/ethyl acetate: 9:1); mp 41 8C
(hexane); n (KBr) 3065, 3051, 3022, 1587 cmK1 (HC]C);
dH 0.74 (3H, t, JZ6.9 Hz, Me), 1.05–1.56 [16H, m,
Me(CH2)8], 2.43 (3H, t, JZ6.3 Hz, CH2S), 7.31–7.51,
7.59–7.75 (9H and 6H, respectively, 2m, ArH); dC 14.1
(Me), 22.7, 27.6, 28.5, 29.0, 29.3, 29.4, 29.5, 31.9, 32.3 (9!
CH2), 128.0 (6C), 130.0 (3C), 133.4 (3C), 135.7 (6C) (ArC);

C. Behloul et al. / Tetrahedron 61 (2005) 6908–6915
6913
m/z (DIP) 432 (MC, 26%), 346 (12), 276 (17), 261 (14), 260
(62), 259 (100), 199 (35), 181 (17); HRMS: MC, found
432.2304. C28H36SSi requires 432.2307.
(6C), 130.0 (3C), 135.2 (3C), 135.7 (6C) (ArC); m/z 375
(MCC1, 18%), 374 (MC, 60), 261 (18), 260 (81), 259
(100), 261 (18), 215 (19), 214 (10), 181 (24), 152 (12), 137
(15), 77 (12); HRMS: MC, found 374.1516. C24H26SSi
requires 374.1524.
4.2.18. (Triphenylsilylthio)benzene (3c).26 white solid;
yield: 41%; Rf 0.82 (hexane/ethyl acetate: 9:1); mp 110 8C
(hexane); n (KBr) 3066, 3049, 3016, 1580 cmK1 (HC]C);
dH 7.15–7.74 (20H, m, ArH); dC 126.8, 127.1 (2C), 127.4
(2C), 127.9 (6C), 128.5 (3C), 130.1 (3C), 135.1, 135.9 (6C)
(ArC); m/z 368 (MC, 25%), 260 (27), 259 (100), 181 (13).
4.5. Naphthalene-catalysed lithiation of silylated
compounds 1–3. Preparation of products 4–6. General
procedure
A solution of the silylated substrate 1–3 (1.0 mmol) in THF
(2 mL) was dropwise added to a green suspension of lithium
powder (63 mg, 9.0 mmol) and naphthalene (20 mg,
0.16 mmol) in THF (5 mL), under Ar, at 0 8C. After stirring
at the same temperature for the time indicated in Table 1,
methanol (5 mL) was carefully added the cooling bath was
removed and the reaction was stirred till it reached room
temperature. The yields of the desilylated compounds were
determined by quantitative GLC using commercially
available alcohols 4, amines 5, thiols 6, n-dodecane (internal
standard) and n-hexadecane (internal standard for 1h) in the
determination of response factors. Compounds 4a, 4b,
4d–4f and 4h–6 (commercially available) were character-
ised by comparison of their physical and spectroscopic data
with authentic samples.
4.3. Preparation of disilylated amino alcohol 1h
n-BuLi (6.3 mL of a 1.6 M solution of n-BuLi in hexane,
10.0 mmol) was dropwise added to a stirred solution of
6-(methylamino)-1-hexanol (656 mg, 5.0 mmol) in
anhydrous THF (7 mL) at 0 8C. 5 min after the addition
had been completed, a solution of triphenylsilyl chloride
(2.832 g, 10.0 mmol) in the same solvent (7 mL) was added
during ca. 5 min. After stirring for 1 h at the same
temperature, the crude reaction mixture was adsorbed on
basic aluminium oxide, transferred to a short column of
basic aluminium oxide and eluted with hexane. Evaporation
of the solvent (15 Torr) gave the pure disilylated amino
alcohol 1h in 53% yield. The corresponding physical,
spectroscopic and analytical data follow.
Compound 1f was deprotonated with n-BuLi (0.69 mL of a
1.6 M solution in hexane, 1.1 mmol) at 0 8C before
submitting it to the reductive cleavage step.
4.3.1. N-Methyl-N-(triphenylsilyl)-6-(triphenylsilyloxy)-
1-hexanamine (1h). White solid; yield: 53%; Rf 0.84
(hexane/ethyl acetate: 9:1); mp 74 8C (hexane); n (KBr)
3064, 3044, 3022, 1587 (HC]C), 1259 (CN), 1182 (SiN),
1109 (SiO), 1027 cmK1 (CO); dH 0.81–0.92, 1.32–1.54 [6H
and 2H, respectively, 2m, (CH2)4CO], 2.65 (3H, s, Me),
2.79 (2H, t, JZ7.4 Hz, CH2N), 3.70 (2H, t, JZ6.6 Hz,
CH2O), 7.28–7.67 (30H, m, ArH); dC 26.1, 26.8, 28.9, 32.5
[(CH2)4CO], 36.2 (Me), 50.9 (CN), 63.9 (CO), 127.6 (6C),
127.8 (6C), 129.3 (3C), 129.9 (3C), 135.4 (6C), 135.6 (3C),
135.9 (6C), 136.4 (3C) (ArC); m/z 388 (MCKPh3Si,
!1%), 277 (24), 276 (98), 261 (15), 260 (64), 259 (100),
257 (10), 238 (15), 199 (100), 198 (16), 197 (19), 183 (15),
182 (26), 181 (57), 180 (19), 155 (15), 152 (11), 122 (33),
105 (16), 77 (19), 42 (22); HRMS: MCKPh3Si, found
388.2096. C25H30NOSi requires 388.2100.
All reactions whose products were isolated (see Table 1)
were hydrolysed with water (5 mL) instead of methanol.
The mixture was extracted with ethyl acetate (3!15 mL)
and the combined organic phases were washed with brine
(5 mL), being then dried over sodium sulfate. After
evaporation of the solvents (15 Torr), the resulting residue
was purified by column chromatography (silica gel, hexane/
ethyl acetate), affording the expected products in the yields
indicated in Table 1. Compound 4c (commercially avail-
able) was characterised by comparison of its physical and
spectroscopic data with an authentic sample. The corre-
sponding physical, spectroscopic and analytical data for
compound 4g follow.
4.5.1. 9-[tert-Butyl(diphenyl)silyloxy]-1-nonanol (4g).
Colourless oil; yield: 63%; Rf 0.30 (hexane/ethyl acetate:
8:2); n (film) 3316 (OH), 3069, 3049, 1596 (HC]C), 1113
(SiO), 1094 cmK1 (CO); dH 1.04 (9H, s, 3!Me), 1.12–1.40,
1.46–1.78 [10H and 5H, respectively, 2m, (CH2)7CO and
OH], 3.59–3.69 (4H, m, 2!CH2O), 7.29–7.49, 7.57–7.72
(6H and 4H, respectively, 2m, ArH); dC 19.2 (CMe3), 26.8
(3C, 3!Me), 25.7, 25.75, 29.3, 29.35, 29.5, 32.5, 32.8
[(CH2)7CO], 63.1, 64.0 (2!CO), 127.5 (4C), 127.9 (2C),
135.0 (2C), 135.6 (4C) (ArC); m/z (DIP) 383 (MCKMe,
24%), 241 (43), 227 (31), 200 (19), 199 (100), 197 (11), 183
(19), 181 (32), 139 (23), 135 (12), 83 (13), 69 (20), 55(11);
HRMS: MCKBut, found 341.1919. C21H29O2Si requires
341.1940.
4.4. Synthesis of silylated thiol 3b
B(C6F5)3 (25 mg, 0.05 mmol) was added to a solution of
cyclohexanethiol (0.63 mL, 5.0 mmol) and triphenylsilyl
chloride (1.342 g, 5.0 mmol) in CH2Cl2 (10 mL) under Ar at
20 8C and the reaction was stirred for four days at the same
temperature.27 The crude reaction mixture was adsorbed on
basic aluminium oxide, transferred to a short column of
basic aluminium oxide and eluted with hexane. Evaporation
of the solvent (15 Torr) gave the pure silylated thiol 3b in
52% yield. The corresponding physical, spectroscopic and
analytical data follow.
4.4.1. (Triphenylsilylthio)cyclohexane (3b). White solid;
yield: 52%; Rf 0.88 (hexane/ethyl acetate: 9:1); mp 103 8C
(hexane); n (KBr) 3066, 3048, 3011, 1588 cmK1 (HC]C);
dH 0.96–1.85 (10H, m, 5!CH2), 2.59–2.74 (1H, m, CH),
7.31–7.53, 7.59–7.76 (9H and 6H, respectively, 2m, ArH);
dC 25.3, 26.1 (2C), 37.1 (2C) (5!CH2), 41.6 (CS), 127.9
4.6. Determination of the optical purity of product (R)-4c
To determine the optical purity of product (R)-4c, it was
reacted with optically pure (R)-a-methoxyphenylacetic acid

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C. Behloul et al. / Tetrahedron 61 (2005) 6908–6915
following a previously described experimental procedure.28
The 13C NMR spectrum of the crude product obtained after
work-up showed the same signals as the ester prepared from
the same acid and commercially available (R)-2-octanol. No
racemization was observed in any case by comparison of the
13C NMR spectra of those esters with the spectrum of
the ester that was prepared by the same method from
racemic 2-octanol.29 The absolute configuration of (R)-4c
was determined by comparison of the sign of its optical
rotation {[a]2D0 K8.8G0.3 (c 1, CHCl3) for the crude
product} with the one of commercially available (R)-2-
octanol {[a]2D0 K9.7G0.3 (c 1, CHCl3)}. The corresponding
physical, spectroscopic and analytical data for the
O-methylmandelate obtained from (R)-4c, as well as the
13C NMR data for the O-methylmandelate prepared from
racemic 2-octanol, follow.
2. (a) Ref. 1c, p 600. (b) Ref. 1d, p 81. (c) Ref. 1e, pp 451–472.
(d) Ref. 1f, pp 595–599.
3. (a) Ref. 1c, p. 482. (b) Ref. 1e, pp 427–432.
4. (a) Nelson, T. D.; Crouch, R. D. Synthesis 1996, 1031–1069.
(b) Schelhaas, M.; Waldmann, H. Angew. Chem., Int. Ed. Engl.
1996, 35, 2056–2083. (c) Crouch, R. D. Tetrahedron 2004, 60,
5833–5871.
5. See, for instance: (a) Clark, J. H. Chem. Rev. 1980, 80,
429–452. (b) Shimshock, S. J.; Watermire, R. E.; Deshong, P.
J. Am. Chem. Soc. 1991, 113, 8791–8796.
6. See, for instance: Collington, E. W.; Finch, H.; Smith, I. J.
Tetrahedron Lett. 1985, 26, 681–684.
7. (a) Toshima, K.; Yanagawa, K.; Mukaiyama, S.; Tatsuta, K.
Tetrahedron Lett. 1990, 31, 6697–6698. (b) Lee, K.; Wiemer,
D. F. J. Org. Chem. 1993, 58, 7808–7812. (c) Cormier, J. F.;
Isaac, M. B.; Chen, L.-F. Tetrahedron Lett. 1993, 34, 243–246.
(d) Rotulo-Sims, D.; Prunet, J. Org. Lett. 2002, 4, 4701–4704.
8. For reviews, see: (a) Yus, M. Chem. Soc. Rev. 1996, 25,
4.6.1. (1R)-1-Methylheptyl (2R)-2-methoxy-2-phenyl-
acetate. Colourless oil; yield: 95%; Rf 0.40 (hexane);
[a]2D0 K21.5G0.5 (c 1, CHCl3); n (film) 3071, 3032, 1494
(HC]C), 1747 (C]O), 1116 cmK1 (CO); dH 0.83 (3H, t,
JZ7.1 Hz, MeCH2), 0.85–1.52 (10H, m, 5!CH2), 1.22
(3H, d, JZ6.2 Hz, MeCH), 3.41 (3H, s, MeO), 4.72 (1H, s,
CHCO), 4.86–5.00 (1H, m, CHO), 7.22–7.63 (5H, m, ArH);
dC 13.9 (MeCH2), 20.0 (MeCO), 22.3, 24.8, 28.7, 31.5, 35.6
(5!CH2), 57.1 (MeO), 71.9 (MeCO), 82.6 (CHPh), 127.1
(2C), 128.4 (2C), 128.5, 136.4 (ArH), 170.3 (C]O); m/z
278 (MC, !1%), 121 (100); HRMS: MC, found 278.1928.
C17H26O3 requires 278.1882.
´
155–161. (b) Ramon, D. J.; Yus, M. Eur. J. Org. Chem. 2000,
225–237. (c) Yus, M. Synlett 2001, 1197–1205. (d) Yus, M.;
´
´
Ramon, D. J. Latv. J. Chem. 2002, 79–92. (e) Ramon, D. J.;
Yus, M. Rev. Cubana Quim. 2002, 14, 75–115. (f) Yus, M. In
The Chemistry of Organolithium Compounds; Rapport, Z.,
Mareck, I., Eds.; Wiley: Chichester, 2004, Chapter 11. For a
mechanistic study, 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) Herrera, R. P.; Guijarro, A.; Yus, M. Tetrahedron Lett.
2003, 44, 1309–1312.
9. For a polymer-supported version of this reaction, see: (a)
´
Gomez, C.; Ruiz, S.; Yus, M. Tetrahedron Lett. 1998, 39,
4.6.2. (1R*)-1-Methylheptyl (2R)-2-methoxy-2-phenyl-
acetate. dC 13.9, 14.05 (2!MeCH2), 19.6, 20.0 (2!
MeCO), 22.3, 22.5, 24.8, 25.2, 28.7, 28.9, 31.5, 31.6, 35.6,
35.7 (10!CH2), 57.1, 57.2 (2!MeO), 71.9, 72.1 (2!
MeCO), 82.6, 82.7 (2!CHPh), 127.0 (2C), 127.1 (2C),
128.4 (4C), 128.5, 128.6, 136.4, 136.5 (ArH), 170.3 (2!
C]O).
´
1397–1400. (b) Gomez, C.; Ruiz, S.; Yus, M. Tetrahedron
´
1999, 55, 7017–7026. (c) Yus, M.; Gomez, C.; Candela, P.
Tetrahedron 2002, 58, 6207–6210. (d) Candela, P.; Gomez,
C.; Yus, M. Russ. J. Org. Chem. 2004, 40, 795–801.
10. For a review, see: Guijarro, D.; Yus, M. Recent Res. Dev. Org.
Chem. 1998, 2, 713–744.
´
11. For reviews, see: (a) Najera, C.; Yus, M. Trends Org. Chem.
´
1991, 2, 155–181. (b) Najera, C.; Yus, M. Recent Res. Dev.
Acknowledgements
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Org. Chem. 1997, 1, 67–96. (c) Najera, C.; Yus, M. Curr. Org.
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Chem. 2003, 7, 867–926. (d) Najera, C.; Sansano, J. M.; Yus,
M. Tetrahedron 2003, 59, 9255–9303. (e) Chinchilla, R.;
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Najera, C.; Yus, M. Chem. Rev. 2004, 2667–2722.
This work was financially supported by the DGES of the
´
Spanish Ministerio de Ciencia y Tecnologia (project no.
BQU2001-0538) and the Generalitat Valenciana (project
no. GRUPOS03/135). C. B. thanks the University of
Alicante for a fellowship.
12. For reviews, see: (a) Yus, M.; Foubelo, F. Rev. Heteroatom
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13. Alonso, E.; Ramon, D. J.; Yus, M. Tetrahedron 1997, 53,
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15. Behloul, C.; Guijarro, D.; Yus, M. Synthesis 2004, 1274–1280.
16. In a previous study, we found that 1-[tert-butyl(diphenyl)-
silyloxy]docosane did not give the desilylation product after
12 h at room temperature. See Ref. 13.
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1
29. We first, tried to compare the H NMR spectra, but we could
not use them to determine the optical purity of product (R)-1c
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esters obtained from racemic 2-octanol.
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