1,1-Disilyl alcohols as d1 synthons: Harnessing the 1,2-Brook rearrangement

Article abstract of DOI:10.1002/1522-2675(200210)85:10<3349::AID-HLCA3349>3.0.CO;2-K

1,1-Disilyl alcohols like 6 give the silyl ethers like 9 on treatment with base and alkyl halides, in a reaction which may be formulated as the alkylation of the Brook-rearranged carbanion 8. The products can be oxidised to give ketones like 10, showing that this Brook-rearranging system supplies a controlled d¹ synthon of the acyl anion class. The alcohols can be prepared from the acid chloride 12 and dimethyl(phenyl)silyllithium, but the intermediate anion 21 need not be worked up; it can be used directly in the alkylation step.

Full text of DOI:10.1002/1522-2675(200210)85:10<3349::AID-HLCA3349>3.0.CO;2-K

Helvetica Chimica Acta Vol. 85 (2002)
3349
1,1-Disilyl Alcohols as d1 Synthons: Harnessing the 1,2-Brook
Rearrangement
by Ian Fleming*, Annabel J. Lawrence1), Robert D. Richardson1), David S. Surry1), and Mark C. West2)
Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW, UK
Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday
1,1-Disilyl alcohols like 6 give the silyl ethers like 9 on treatment with base and alkyl halides, in a reaction
which may be formulated as the alkylation of the Brook-rearranged carbanion 8. The products can be oxidised
to give ketones like 10, showing that this Brook-rearranging system supplies a controlled d1 synthon of the acyl
anion class. The alcohols can be prepared from the acid chloride 12 and dimethyl(phenyl)silyllithium, but the
intermediate anion 21 need not be worked up; it can be used directly in the alkylation step.
Introduction.
The 1,2-Brook rearrangement is usually formulated as an
equilibrium between an oxy anion having an a-silyl substituent, such as 1, and a
carbanion having an a-silyloxy substituent, such as 2, with the former normally in high
concentration and the latter in low concentration [1]. Whether or not this is an accurate
description of the species present3), it often reacts with electrophiles as a carbon
nucleophile, and as such it can be classified as a d1 synthon [3].
For example, if benzaldehyde (PhCHO) is treated with dimethyl(phenyl)silyllithi-
um (Me2PhSiLi) the products are the a-silylbenzyl alcohol 3 and, after workup, the
pinacol 4 (Scheme 1) [4]. The latter is the product from the reaction of an anion 2 with
another molecule of PhCHO, but it is not possible to use this nucleophile with a range
of electrophiles. Although homocoupling is relatively easy, as here, it is limited to
aromaticaldehydes and ketones [5], because easy Brook rearrangement 1 ! 2 needs
the stabilisation of the carbanion provided by the aromatic ring. We have found, as
Kuwajima and co-workers have also [6], that it can also be made to give a cross-coupled
pinacol 5, but only when the electrophilic component is a nonenolisable aldehyde [7].
The yield was low, there were several other products, and it was clear that this was not a
general or reliable way of gaining access to a reliable d1 synthon.
The Brook rearrangement can be set up in several ways: most commonly when an
a-silylcarbinol is treated with base [8], when an aldehyde or ketone is treated with a
silyllithium reagent [9], or when an acylsilane is treated with a nucleophile [10]. There
are a few reactions in which a Brook rearrangement, set up in one of these ways, is the
1
)
)
)
Work carried out in an undergraduate research project, Cambridge, 2001 2002.
Taken from the Ph.D. Thesis of M. C. W., Cambridge University, 2001.
Calculations of the structure in the gas phase [2] suggest that a pentacoordinate silyl anion is the species
present, rather than a mixture of 1 and 2 in equilibrium. If this proves to be the case in solution, the
reactions will have to be reformulated somewhat, but, for the purposes of this paper and for simplicity, we
continue to use the language of an equilibrating mixture.
2
3

3350
Helvetica Chimica Acta Vol. 85 (2002)
Scheme 1
OH
OSiMe2Ph
O
1. tBuCHO
PhMe2SiLi
tBu
Ph
PhCHO
Ph
Ph
Ph
SiMe2Ph
2. HCl, MeOH
OH
1
2
5
28%
PhCHO
OH
OH
Ph
Ph
SiMe2Ph
OH
3
4
basis of a reliable and versatile syntheticmethod [11]. Brook rearrangements assisted
by the presence of a vinyl or ethynyl group, in place of the aryl group in the examples
mentioned above, usually give the product of g-alkylation or protonation, and, hence,
the formation of a specific silyl enol ether [6][12]. Similarly, a Brook rearrangement
induces elimination to give a specific silyl enol ether when there is a nucleofugal group
adjacent to the CÀO bond [13]. Attack of an enolate on an a,b-unsaturated acylsilane,
can lead to five- or seven-membered-ring formation [14], while enolate attack on a
saturated acylsilane gives a cyclopropanediol [15]. Only in the last of these reactions is
the Brook rearrangement being used for its potential as a d1 synthon, as it is also in a
formal sense in those reactions in which it is protonated [16], a reaction of
comparatively limited usefulness in synthesis, or silylated in a retro-Brook rearrange-
ment [17]. Otherwise, Brook rearrangements only turn up as one step in reactions
which make excellent seminar problems [18][19], but which are not generally useful.
Reports of the a-alkylation of a Brook-rearranging system are few, and all rely upon
the anion-stabilising ability of an aromaticring [20]. We now report that we have tamed
the Brook rearrangement so that it can be used as a d1 synthon with alkyl halides: 1,1-
disilyl alcohols typified by 6 on treatment with base can be alkylated on the C-atom in
the sense 8 ! 9 (Scheme 2). The second silyl group is evidently good enough at
stabilising an anion to allow easy Brook rearrangement, even though there is no
stabilisation from an aromaticgroup. The relief of stericcompression may also be
helping. The product 9 can be hydrolysed and oxidised to give a ketone 10, revealing
the full capacity of the Brook-rearranging system as an acyl-anion equivalent.
Results and Discussion.
The Preparation of 1,1-Disilyl Alcohols. 1,1-Bis(tri-
methylsilyl) alcohols such as the alcohol 11 have been prepared by Kuwajima et al. by
reductive silylation of esters with Na and Me3SiCl in refluxing THF, followed by acidic
hydrolysis to remove the O-silyl group [21]. We repeated this synthesis with small a
modification.
We reported earlier that the Me2PhSi analogues can be made by treating phenyl
esters with an excess of Me2PhSi in a mixture of THF and toluene [22]. For the present
work, we have used a short-cut, which is an improvement over the earlier method. Since
we had been making the phenyl esters from the acid chlorides, it is one step shorter to
treat the acid chlorides 12 directly with slightly more than 2 equiv. of the silyllithium

Helvetica Chimica Acta Vol. 85 (2002)
Scheme 2
3351
OH
O
PhMe2SiO SiMe2Ph
SiMe2Ph
SiMe2Ph
1. TBAF
2. CrO3
1. BuLi
2. Br
6
9
10
Br
BuLi
O
Li
OSiMe2Ph
SiMe2Ph
8
SiMe2Ph
SiMe2Ph
7
reagent (Scheme 3). There was some risk in using this approach, since the product
anion such as 7/8 might have reacted with the acid chloride. In practice this is not a
problem slow addition of the silyllithium reagent to the acid chloride works just as
well as addition of the acid chloride to the silyllithium reagent. Furthermore, the
sodium alkoxide, related to 7/8 and derived from the alcohol 6 with NaH, did not react
Scheme 3
OH
CO2Me
SiMe3
SiMe3
1. Na/K, Me3SiCl
2. H3O+
11
49%
OH
COCl
SiMe2Ph
1. 2PhMe2SiLi
2. H3O+
SiMe2Ph
6
94%
12c
OH
R1
R2
COCl
COCl
R1
R2
SiMe2Ph
SiMe2Ph
1. 2PhMe2SiLi
2. H3O+
R3
R3
12
13
OSiMe2Ph
H
1. 2PhMe2SiLi
2. H3O+
SiMe2Ph
14

3352
Helvetica Chimica Acta Vol. 85 (2002)
with 3,5-dinitrobenzoyl chloride, even after 18 h at room temperature. This matches
other results we have obtained, showing that many of the standard reagents used to
dehydrate alcohols fail completely to react with the 1,1-disilyl alcohol 6, which is
recovered unchanged [23].
We had used phenyl esters earlier, in order to avoid the formation of products in
which a Ph group has migrated from the Si- to the C-atom, giving unwanted by-
products when alkyl esters had been used. We deduced at that time that the low pKa of
the liberated PhOÀ ion makes it less effective in setting off this rearrangement, and ClÀ
ion can obviously be expected to be even better in this respect. We have seen no sign of
these rearranged products in any of our recent preparations, and we have obtained
good yields of the 1,1-disilyl alcohols 13 in almost every case (Table 1). Care has to be
taken to quench the reaction mixture with acid at low temperature and in the presence
of an organic solvent to extract the product rapidly. Less-careful workup is apt to give
some of the monosilylated alcohol, the product of a premature Brook rearrangement
and protonation. This problem is much more severe when Ph3SiLi is used in place of
Me2PhSiLi, when we were unable to prevent the Brook rearrangement. Benzoyl
chloride also gave directly the product 14 with one C-silyl and one O-silyl group.
Table 1. Synthesis of Alcohols 13 from Me2PhSiLi and Acid Chloride 12
Starting material
Product
Yield
[%]
R1
R2
R3
12a
12b
12c
12d
12e
12f
12g
12h
12i
Bu
C8H17
H
H
H
H
H
H
H
H
H
H
H
13a
13b
77
29
94
87
72
87
76
62
63
À(CH2)5À
À(CH2)4À
À(CH2)3À
13c ( ˆ 6)
13d
13e
13f
13g
13h
Me
Me
iPr
Me
H
Me
Me
Ph
13i
Except in these unsuccessful cases, it appears that the protic acid used in the workup
had given O-protonation of the oxy anion with kineticcontrol, and not C-protonation,
which was the result of thermodynamic control when the oxy anion had been allowed to
spend any time in a proticsolvent. Extending this observation, we reaclled that
Kuwajima et al. had recommended lithium alkoxides derived from 1,1-bis(trimethyl-
silyl) alcohols as hindered bases in controlled aldol reactions [21][24]. We imitated one
of these, the reaction between methyl isopropyl ketone 16 and pentanal 15, using the
lithium alkoxide 17 derived from pivaloyl chloride (Scheme 4). We isolated the aldol
product 18 in good yield, comparable to Kuwajima×s, but we also looked for, and
isolated in even better yield, the product derived from the base. This proved to be the
C-protonated silyl ether 19, showing that kineticprotonation of the Brook-rearranging
system by the carbon acid had taken place on the C-atom. This helps to explain the
special properties of this type of base that Kuwajima et al. had observed. The removal
of the proton from the ketone by a carbon base is effectively irreversible, making the

Helvetica Chimica Acta Vol. 85 (2002)
3353
base similar in its properties to LDA: hindered, so that it easily deprotonates only the
methyl ketone group, and strong, so that it induces complete deprotonation. Kuwajima
et al. suggested that this kind of base would have a pKa value between that of an
alkoxide and a metal amide, and, in another context, mentioned the possibility of a
Brook rearrangement [25], but he did not isolate the product derived from his base.
Since it is evidently a carbon base, its pKa value will indeed be very high.
Scheme 4
Li
O
SiMe2Ph
SiMe2Ph
OSiMe2Ph
O
OH
O
17
H
CHO
+
+
SiMe2Ph
15
16
18
19
80%
97%
There appears to be an emerging pattern with Brook-rearranging intermediates like
7/8, in which hard electrophiles, like protic acids, attack the O-atom, and soft
electrophiles, like the a-H-atom of a methyl ketone, at the C-atom. This simple
perception sets the scene for the alkylations we describe below.
Brook Rearrangement of 1,1-Disilylalkoxides and Their C-Alkylation. Typically, we
treated the disilyl alcohols 11 and 13 with BuLi at 08 in Et2O, using 2,2-bipyridine to
indicate when 1 equiv. had been added, and then added an excess of an alkyl halide.
Reaction took place slowly; allyl bromide, for example, and the anion 7/8 derived from
the alcohol 13c (ˆ6) required a little over 5 h at room temperature to complete the
formation of the silyl ether 9. Accordingly, we usually left the mixtures at room
temperature overnight, and invariably obtained the products 20 of C-alkylation,
sometimes contaminated with the product of C-protonation, but with no sign of any O-
alkylation (Scheme 5). This is in contrast to the O-methylation seen between an a-silyl
alkoxide and dimethyl sulfate [26], a harder alkylating agent than the alkyl halides that
we have used. Alkyl halides undergoing SN2 reactions are, of course, soft electrophiles,
and these are the ones that work, ranging from the reactive and usually high-yielding
allyl bromide, PhCH2Br and MeI, to the less-reactive and lower-yielding i-PrI, i-BuI,
and 3-(trimethylsilyl)propargyl bromide (Table 2). The low yield with i-PrI may have
been due to competing elimination; certainly there was no Brook-rearranging anion
still unchanged at the end of the 18 h in the case of 13c, for the addition of MeI at this
stage gave none of the product of methylation 20cc. Alkyl halides that failed to give any
Scheme 5
OH
PhMe2SiO SiMe2Ph
1. BuLi
2. R4X
R1
R2
SiMe2Ph
SiMe2Ph
R1
R4
R2
R3
R3
13
20

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Helvetica Chimica Acta Vol. 85 (2002)
Table 2. Alkylation of 1,1-Disilylalkoxides with BuLi and Alkyl Halides
Starting material
Alkyl halide
R4
Product
Yield
[%]
R1
R2
R3
X
a
11
11
11
allyl
Bn
iPr
allyl
Bn
Me
Br
Br
I
Br
Br
I
I
I
I
I
52
67
)
)
b
50c)
98
13c ( ˆ 6)
13c ( ˆ 6)
13c ( ˆ 6)
13c ( ˆ 6)
13c ( ˆ 6)
13c ( ˆ 6)
13c ( ˆ 6)
13d
À(CH2)5À
H
H
H
H
H
H
H
H
H
H
20ca (ˆ9)
20cb
20cc
20cd
20ce
20cf
20cg
20da
20ea
20fe
À(CH2)5À
À(CH2)5À
À(CH2)5À
À(CH2)5À
À(CH2)5À
À(CH2)5À
À(CH2)4À
À(CH2)3À
83
82
72
48
43
37
89
89
Et
iPr
iPrCH2
CH2CꢀCSiMe3
allyl
allyl
iPr
Br
Br
I
13e
13f
Me
Me
61/60
a) Product analogous to 20ca but with Me3Si groups in place of Me2PhSi groups. b) Product analogous to 20cb
but with Me3Si groups in place of Me2PhSi groups. c) Product analogous to 20ce but with Me3Si groups in place
of Me2PhSi groups.
identifiable products other than that of C-protonation were ethyl a-bromoacetate,
ethyl b-bromopropionate, and (cyclopropyl)methyl bromide.
Alternative bases that can be made to work are NaH and KH, but we find that,
although they may be worth trying in some cases, they are usually more troublesome,
giving more of the products of protonation unless exceptional care is taken to keep the
mixture dry and HOÀ ion free. We speculated that the sodium alkoxide might have
been a reactive enough base to deprotonate THF, either at C(2), as often occurs with
alkyllithium reagents [27], or at C(3), as we had found for a somewhat similarly
constituted intermediate in our work on the reaction of silyllithium reagents with
tertiary amides [19]. The experiment with 3,5-dinitrobenzoyl chloride and the sodium
alkoxide derived from the alcohol 6, mentioned above, was designed to test this
hypothesis, but, in addition to giving no reaction with the alkoxide, it gave no product
derived from the THF either the products were the C-protonated silyl ether derived
from 8 and 3,5-dinitrobenzoicaicd. A similar experiment attempting to trap an
elimination product from the THF with (t-Bu)Me2SiCl was equally unsuccessful.
One-Pot Reaction of the Acid Chloride Successively with the Silyllithium Reagent
and an Alkyl Halide. Having found that the lithium alkoxide was in general the most
straightforward, we considered that it might be more simple not to isolate the disilyl
alcohol, but to use directly its lithium alkoxide 21, which must have been formed in the
reaction between the acid chloride 12 and the silyllithium reagent (Scheme 6). This
idea worked well. In general, it has given us higher yields (Table 3), it is easier to carry
out, and the workup is straightforward, during which there is no hydrolysis of the silyl
ether. The only drawback is that any excess silyllithium reagent consumes the alkyl
halide faster than the Brook-rearranging nucleophile, and the nonpolar alkyldime-
thyl(phenyl)silane has to be separated from the hardly more polar silyl ethers 20.
Oxidation of the Productsto give Ketones . We have carried out hydrolysis and
oxidation on three of our products, in order to illustrate their potential as d1 synthons

Helvetica Chimica Acta Vol. 85 (2002)
3355
Scheme 6
Li
O
PhMe2SiO SiMe2Ph
R4X
R1
R2
R1
R2
R1
R4
R2
R3
2 PhMe2SiLi
COCl
SiMe2Ph
SiMe2Ph
R3
R3
12
21
20
Table 3. Alkylation of 1,1-Disilylalkoxides with Alkyl Halides in situ
Starting material
R1
Alkyl halide
R4
Product
Yield
[%]
R2
R3
X
12a
12a
12b
12c
12c
12c
12f
12f
12f
12f
12j
12j
Bu
Bu
C8H17
H
H
H
H
H
H
H
H
H
H
H
H
H
Me
Me
allyl
iPr
allyl
allyl
iPr
iPrCH2
allyl
Bn
Br
I
Br
Br
I
20aa
20ae
20ba
20ca ( ˆ 9)
20ce
20cf
20fa
20fb
20fc
66
30
41
91/98
65a)
45
75
50
À(CH2)5À
À(CH2)5À
À(CH2)5À
I
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Br
Br
I
Br
Br
Br
Me
62
Br(CH2)3
allyl
Bn
20ff
20ja
20jb
40b)
98
82
a) Together with the silyl ether (30%) from protonation in place of alkylation. b) As the alcohol, after hydrolysis
of the silyl ether with TsOH in EtOH.
(Scheme 7). The silyl ethers, since they are substantially hindered, are slow to hydrolyse
in acid, with the conversion 20ca ! 22 almost certainly not as good as it could be, but
they cleanly give a-silyl alcohols such as 24 on treatment with tetrabutylammonium
fluoride (TBAF) in THF typically for 4 h at room temperature. Longer treatment with
TBAF smoothly removes the second silyl group, giving a simple secondary alcohol such
as 26, and it may be that, in preparation for oxidation, there is not much point in trying
to remove only the O-silyl group. The oxidation may be carried out with several of the
reagents normally used for oxidising secondary alcohols to ketones. We have used
pyridinium chlorochromate (PCC) in this work, giving the ketones, 23, 25 and 27 in
good yield.
Some Related Observations. Our attempts to use carbon electrophiles other than
alkyl halides have been disappointing. There is precedent for aldehydes reacting [6],
but they did not give us recognisable products. Epoxides gave no sign of any reaction,
but we eschewed the use of hexamethylphosphoric triamide (HMPA), which might
well be a necessary cosolvent. We have already commented on the failure of acid
chlorides to react. One alkyl halide understandably gave a different outcome
(Scheme 8) from those described above: CH2Br2 reacted with the Brook-rearranging
system 7/8 prepared in situ from the acid chloride 12c to give directly the silyl enol ether
28, hydrolysis of which gave the methyl ketone 29, avoiding the use of conventional
oxidising agents.

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Helvetica Chimica Acta Vol. 85 (2002)
Scheme 7
O
HO SiMe2Ph
PhMe2SiO SiMe2Ph
HCl, MeOH
PCC
2 h
20ca
22 59%
23 83%
O
HO SiMe2Ph
PhMe2SiO SiMe2Ph
TBAF, THF
4 h
PCC
PCC
20cf
24 81%
25 85% (NMR)
OH
O
PhMe2SiO SiMe2Ph
TBAF, THF
18 h
20ce
26 95%
27 93%
Scheme 8
O
OSiMe2Ph
O
1. 2 PhMe2SiLi
2. CH2Br2
HCl, MeOH
Cl
12c
28
29 76%
O
PhMe2SiO SiMe2Ph
HO SiMe2Ph
1. 2 PhMe2SiLi
2. AllylBr
HCl
Cl
MeOH
30
31 80%
OSiMe2Ph
OH
HO SiMe2Ph
1. BuLi
TBAF
2. AllylBr
31
32
33 91%
The preparation of the Brook-rearranging system directly from the acid chloride
allowed us to overcome the premature Brook rearrangement protonation, giving the
silyl ether 14 that we had unavoidably suffered when we tried to prepare the disilyl
alcohol from PhCOCl. Starting again with PhCOCl, but adding allyl bromide after the
silyllithium reagent, gave the silyl ether 30, hydrolysis of which gave the alcohol 31. This

Helvetica Chimica Acta Vol. 85 (2002)
3357
alcohol, because of the activating Ph group, could be induced to undergo a second
Brook rearrangement alkylation to give the silyl ether 32 and hence the alcohol 33.
Among heteroatom electrophiles, two are perhaps worth noting (Scheme 9). The
Brook-rearranging system derived from 13f with BuLi reacted with CCl4 to give cleanly
the acylsilane 34, in a reaction that resembles Kuwajima×s oxidation of a similar system
using tert-butyl hypochlorite [28]. Kuwajima formulated this reaction as O-chlorina-
tion, followed by elimination of Me3SiCl. Given that CCl4 and tert-butyl hypochlorite
are soft electrophiles, it now seems more likely that it takes place by Brook
rearrangement and C-chlorination, followed by elimination of the silyl chloride. The
system 7/8 derived from the disilyl alcohol 6 reacted with methane chlorosulfite to give
the product of C-sulfination 35 apparently as a single diastereoisomer. It was this
observation, another fruitless attempt to induce dehydration and/or cationic rearrange-
ment [23], that led us to the present work.
Scheme 9
OH
O
SiMe2Ph
SiMe2Ph
1. BuLi
2. CCl4
SiMe2Ph
82%
13f
34
OH
PhMe2SiO SiMe2Ph
1. BuLi, Et2O, 0°
2. ClS(O)OMe
SiMe2Ph
SiMe2Ph
OMe
S
O
70%
35
6
Conclusions. Silicon-based solutions to all the d synthons are now in place: d2 is
supplied by the conspicuously useful silyl enol ethers [29], d4 by silyl dienol ethers [30],
d3 had been achieved by means of the Brook rearrangement with a neighbouring vinyl
group [6][12], and the present work, together with another recent publication [31] with
a different method altogether, fills in the gap for d1.
Experimental Part
Synthesis of the 1,1-Disilyl Alcohols 13. Typically, the acid chloride (10 mmol) in toluene (5 ml) was added
dropwise over 3 min to Me2PhSiLi [32] (1 mol dmÀ3 soln. in THF, 22 ml, 22 mmol) and toluene (20 ml) under N2
at À788 with vigorous stirring. After 0.5 1 h, the soln. was poured into hexane (100 ml) and aq. NH4Cl soln., the
org. layer separated, washed with HCl (3m, 30 ml) and with brine (30 ml), dried (MgSO4), and evaporated
under reduced pressure. The residue was chromatographed (SiO2; hexane/Et2O) to give the 1,1-disilyl alcohols.
In some cases, the product was distilled (bulb-to-bulb). The following new compounds were prepared by this
method, the alcohols 13b, 13c and 13f being known compounds [22].
1,1-Bis[dimethyl(phenyl)silyl]hexanol (13a; 77%). Oil. TLC (hexane/Et2O, 90 :10): Rf 0.43. IR (film):
1
3556, 2955, 2855, 1465, 1427, 1249, 1110. H-NMR (400 MHz, CDCl3): 7.60 (4m, Ph); 7.43 7.35 (6m, Ph); 1.73
(2dd, J ˆ 8.5, 7.5, CH2CO); 1.34 1.13 (6m, CH2); 0.87 (3t, J ˆ 7.0, Me); 0.37 (3s, MeAMeBSi), 0.31 (6s,
MeAMeBSi). 13C-NMR (100 MHz, CDCl3): 137.9 (i-Ph); 134.6 (o-Ph); 129.0 (p-Ph); 127.6 (m-Ph); 63.6

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Helvetica Chimica Acta Vol. 85 (2002)
(CSi2OH); 37.6 (CH2CSi2O); 32.7 (CH2); 25.0 (CH2); 22.4 (CH2); 13.9 (Me); À2.9 (MeAMeBSi); À3.3
‡
(MeAMeBSi). ESI-MS (C12H34NaOSi2; calc. 393.2046): 393.2046 ([M ‡ Na] ).
Bis[dimethyl(phenyl)silyl](cyclopentyl)methanol (13d; 87%) as an oil. TLC (hexane/AcOEt, 90 :10): Rf
0.50. IR (film): 3554, 2954, 1427, 1250, 1108. 1H-NMR (400 MHz, CDCl3): 7.58 (4m, Ph); 7.38-7.30 (6m, Ph); 2.05
(1tt, J ˆ 7.5, 2.0, CHCO); 1.56 1.10 (9m, OH, 4 CH2); 0.35 (6s, MeAMeBSi), 0.19 (6s, MeAMeBSi). 13C-NMR
(100 MHz, CDCl3): 139.1 (i-Ph); 134.7 (o-Ph); 128.9 (p-Ph); 127.7 (m-Ph); 67.5 (CSi2OH); 48.9 (CHCOSi2);
‡
29.0 (2 CH2); 24.9 (2 CH2); À1.3 (MeAMeBSi); À1.8 (MeAMeBSi). EI-MS: no M observed, 235.1 (40, [M À
‡
‡
SiMe2Ph] ), 135.1 (100, SiMe2Ph ).
Bis[dimethyl(phenyl)silyl](cyclobutyl)methanol (13e; 72%). Oil. TLC (hexane/AcOEt 90 :10): Rf 0.46. IR
(film): 3547, 2956, 1427, 1251, 1108. 1H-NMR (400 MHz, CDCl3): 7.57 (4m, Ph); 7.44 7.34 (6m, Ph); 2.88 (tt, J ˆ
10.0, 7.5, CHCO); 1.85 (2m, CH2); 1.70 1.41 (4m, CH2); 1.30 (br. s, OH); 0.25 (6s, MeAMeBSi); 0.18 (6s,
MeAMeBSi). 13C-NMR (100 MHz, CDCl3): 138.0 (i-Ph); 134.6 (o-Ph); 129.0 (p-Ph); 127.6 (m-Ph); 65.8
(CSi2OH); 42.6 (CHCOSi2); 25.7 (2 CH2); 18.6 (CH2); À2.1 (MeAMeBSi); À2.9 (MeAMeBSi). ESI-MS
‡
(C21H30NaOSi2; calc. 377.1733): 377.1713 ([M ‡ Na] ).
1,1-Bis[dimethyl(phenyl)silyl]propan-1-ol (13g; 76%). Oil. TLC (hexane/Et2O 90 :10): Rf 0.43. IR (film):
1
3556, 2955, 2855, 1465, 1427, 1249, 1110. H-NMR (400 MHz, CDCl3): 7.62 (4m, Ph); 7.43 7.37 (6m, Ph); 1.83
(2q, J ˆ 8.0, MeCH2); 0.91 (3t, J ˆ 8.0, MeCH2); 0.39 (6s, MeAMeBSi); 0.32 (6s, MeAMeBSi). 13C-NMR
(100 MHz, CDCl3): 138.7 (i-Ph); 136.6 (o-Ph); 129.0 (p-Ph); 128.7 (m-Ph); 65.9 (CSi2OH); 29.8 (CH2CSi2O);
10.9 (Me); À2.9 (MeAMeBSi); À3.2 (MeAMeBSi). ESI-MS (C19H28NaOSi2; calc. 351.1577): 351.1584 ([M ‡
‡
Na] ).
1,1-Bis[dimethyl(phenyl)silyl]-2,3-dimethylbutan-1-ol (13h; 62 %). Prepared from 2,3-dimethylbutyryl
chloride [33]. Oil. TLC (hexane/Et2O 97:3): Rf 0.16. IR (film): 3500w (OH), 2960, 1427, 1254, 1118. 1H-NMR
(400 MHz, CDCl3): 7.54 (4m, Ph); 7.41 7.33 (6m, Ph); 2.01 1.86 (m, Me2CH); 1.83 1.76 (m, i-PrCH); 0.88 (3d,
J ˆ 7.5, Me); 0.78 (3d, J ˆ 7.5, MeAMeBCH); 0.75 (3d, J ˆ 7.5, MeAMeBCH); 0.37 (3s, MeSi); 0.35 (3s, MeSi);
0.31 (3s, MeSi), 0.28 (3s, MeSi). 13C-NMR (100 MHz, CDCl3): 138.8 (i-Ph); 138.6 (i-Ph); 134.2 (o-Ph); 133.9 (o-
Ph); 129.2 (p-Ph); 128.9 (p-Ph); 127.7 (m-Ph); 127.6 (m-Ph); 71.0 (CSi2OH); 36.1 (CHCOSi2); 29.1 (Me2CH);
22.6 (MeAMeBCH); 22.6 (MeAMeBCH); 22.0 (i-PrCHMe), À0.7 (MeSi); À0.8 (MeSi); À2.9 (MeSi); À3.1
‡
‡
‡
(MeSi). EI-MS: M not observed, 235.1 (40, [M À SiMe2Ph] ), 135.1 (100 SiMe2Ph ).
1,1-Bis[dimethyl(phenyl)silyl]-2-phenylpropan-1-ol (13i; 63%). Yellow oil. TLC (hexane/Et2O 97:3): Rf
0.36. IR (film): 3468, 2950, 1580, 1431, 1247, 1110. 1H-NMR (400 MHz, CDCl3): 7.64 (2m, Ph); 7.48 7.07 (13m,
Ph); 3.06 (1q, J ˆ 7.5, PhCH); 1.30 (d, J ˆ 7.5, Me); 0.48 (3s, MeSi); 0.36 (3s, MeSi); 0.0 (3s, MeSi); À0.11 (3s,
MeSi). 13C-NMR (100 MHz, CDCl3): 143.1, 139.0, 138.6 (3 i-Ph); 134.9, 134.7, 129.0, 128.9, 128.7, 128.1, 127.5,
127.4, 126.6 (9 Ph); 68.1 (COHSi2); 46.5 (CHPh); 16.6 (Me); À0.6, À1.8, À1.9, À2.6 (4 MeSi). EI-MS
‡
(C20H36OSi2; calc. 348.2305): 348.2300 (M ).
Brook Rearrangement-Alkylation Reactionswith 1,1-Disilyl Alcohols . Typically, BuLi (1m in hexane, 1 ml,
1 mmol) was added to the alcohol (1 mmol) and 2,2'-bipyridine (1 mg) in Et2O (5 ml). After 5 min, the alkyl
halide (2 mmol) was added. After 12 h, the mixture was diluted with hexane (20 ml) and passed through a silica
pad to remove inorganics. The eluant was evaporated under reduced pressure and, if necessary, purified further
by column chromatography (SiO2, Et2O/hexane). The following compounds were prepared by this method.
4-Cyclohexyl-(Trimethylsilyl)-4-(trimethylsilyloxy)but-1-ene (52%). Oil. TLC (hexane): Rf 0.66. IR (film):
3077 (CˆCH), 2931, 2852, 1638, 1450, 1248, 1077. 1H-NMR (400 MHz, CDCl3): 5.73 (ddt, J ˆ 17.5, 11.0, 7.0,
CHˆCH2); 5.11 4.99 (2m, CHˆCH2); 2.53 (dd, J ˆ 14.0, 7.0, CHAHBCˆC); 2.41 (dd, J ˆ 14.0, 7.0,
CHAHBCˆC); 1.34 1.00 (6m); 0.93 0.76 (4m); 0.10 (9s, Me3Si); 0.05 (9s, Me3Si). 13C-NMR (100 MHz,
CDCl3): 135.0 (CˆCH2); 117.0 (CˆCH2); 78.1 (CO); 44.2 (CH2CˆC); 41.3 (CHCO); 30.0 (CH2); 29.4 (CH2);
‡
27.0 (CH2); 26.7 (CH2); 26.4 (CH2); 3.2 (Me3Si); À0.6 (Me3Si). EI-MS ([C16H34OSi2 À Me] ; calc. 283.1913):
‡
‡
283.1928 ([M À Me] ), no M observed.
1-Cyclohexyl-2-phenyl-1-(trimethylsilyl)-1-(trimethylsilyloxy)ethane (67%). Oil. TLC (hexane): Rf 0.34. IR
(film): 2918, 1451, 1253, 1248 (CÀO). 1H-NMR (400 MHz, CDCl3): 7.26 7.15 (5m, Ph); 2.94 (d, J ˆ 8.0,
CHAHBPh); 2.86 (d, J ˆ 8.0, CHAHBPh); 1.93 1.62 (5m, CH, CH2); 1.31 1.10 (6m, CH2); 0.13 (9s, Me3Si);
À0.13 (9s, Me3Si). 13C-NMR (100 MHz, CDCl3): 139.0 (i-Ph); 131.1 (o-Ph); 127.6 (m-Ph); 125.9 (p-Ph); 79.2
(CO); 45.3 (PhCH2); 41.1 (CHCO); 28.9 (CH2); 28.7 (CH2); 26.9 (CH2); 26.8 (CH2); 3.3 (Me3Si); À0.5
‡
(Me3Si). EI-MS (C20H36OSi2; calc. 348.2305): 348.2300 (M ).
1-Cyclohexyl-2-methyl-1-(trimethylsilyl)-1-(trimethylsilyloxy)propane (50%). Oil. TLC (hexane): Rf 0.38.
IR (film): 2903, 1258, 1076 (SiOC). 1H-NMR (400 MHz, CDCl3): 2.02 (sept., J ˆ 6.5, Me2CH); 1.86 1.58 (6m,
CHax); 1.30 1.12 (5m, CHeq); 0.11 (9s, Me3Si); 0.09 (9s, Me3Si). 13C-NMR (100 MHz, CDCl3): 82.0 (CÀO); 46.7

Helvetica Chimica Acta Vol. 85 (2002)
3359
(CH ring); 34.7 (Me2CH); 29.5 (CH2); 29.0 (CH2); 27.2 (CH2); 26.9 (CH2); 26.4 (CH2); 2.6 (Me3Si); 1.0 (Me3Si).
‡
ESI-MS: no M observed.
4-Cyclohexyl-4-[dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]but-1-ene (20ca ˆ 9; 98%). Oil. TLC
(hexane): Rf 0.47. IR (film): 2900, 1635, 1448, 1248, 1110. 1H-NMR (400 MHz, CDCl3): 7.63 7.55 (4m, Ph);
7.40 7.29 (6m, Ph); 5.80 (ddt, J ˆ 17.5, 10.5, 7.0, CHˆCH2); 5.06 4.98 (2m, CHˆCH2); 2.57 (dd, J ˆ 14.5, 7.0,
CHAHBCˆC); 2.51 (dd, J ˆ 14.5, 7.0, CHAHBCˆC); 1.84 (m, CHCO); 1.76 1.50 (5m, CHeq); 1.76 1.50 (5m,
CHax); 0.45 (3s, MeSi); 0.44 (3s, MeSi); 0.41 (6s, MeSi). 13C-NMR (100 MHz, CDCl3): 140.4 (i-Ph); 138.6 (i-Ph);
134.6 (CˆCH2); 134.4 (o-Ph); 133.4 (o-Ph); 128.6 (p-Ph); 128.3 (p-Ph); 127.4 (m-Ph); 127.2 (m-Ph); 117.2
(CˆCH2); 78.7 (CO); 43.3 (CH2CˆC); 41.1 (CHCO); 28.9 (CH2); 27.7 (CH2); 26.5 (CH2); 26.5 (CH2); 26.3
‡
(CH2); 1.8 (MeSi); 1.6 (MeSi); À2.1 (MeSi). ESI-MS (C26H38NaOSi2; calc. 445.2359): 445.2348 ([M ‡ Na] ).
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]-2-phenylethane (20cb; 83%). Oil.
TLC (hexane/Et2O, 96 :4): Rf 0.56. IR (film): 2887, 1594, 1450, 1247, 1110. 1H-NMR (400 MHz, CDCl3):
7.58 7.46 (4m, Ph); 7.40 7.28 (6m, Ph); 7.24 7.17 (3m, Ph); 7.11 (2m, Ph); 3.12 (d, J ˆ 14.5, PhCHAHB); 3.07 (d,
J ˆ 14.5, PhCHAHB); 1.98 (m, CHCO); 1.85 1.62 (5m, CHax); 1.21 1.04 (5m, CHeq); 0.36 (3s, MeSi); 0.33 (3s,
MeSi); 0.24 (3s, MeSi); 0.19 (3s, MeSi). 13C-NMR (100 MHz, CDCl3): 141.0, 139.0, 137.9 (3 i-Ph); 134.9, 133.4,
131.1 (3 o-Ph); 128.4, 128.3 (2 p-Ph); 127.7, 127.4, 127.3 (3 m-Ph); 126.2 (p-Ph); 81.2 (CO); 45.0 (PhCH2); 41.6
(CHCO); 29.9 (CH2); 29.3 (CH2); 26.7 (CH2); 26.6 (CH2); 25.5 (CH2); 2.1 (MeSi); 1.5 (MeSi); À1.3 (MeSi);
‡
À2.4 (MeSi). EI-MS: no M observed.
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]ethane (20cc; 82%). Oil. TLC (hex-
ane): Rf 0.34. IR (film): 2937, 1425, 1250, 1109. 1H-NMR (400 MHz, CDCl3): 7.65 7.58 (4m, Ph); 7.45 7.34 (6m,
Ph); 1.95 0.91 (14m, Me, CHax, CHeq); 0.30 (6s, MeSi); 0.22 (3s, MeSi); 0.21 (6s, MeSi). 13C-NMR (100 MHz,
CDCl3): 140.6 (i-Ph); 138.9 (i-Ph); 134.7 (o-Ph); 133.3 (o-Ph); 129.2 (p-Ph); 128.9 (p-Ph); 127.6 (m-Ph); 127.5
(m-Ph); 79.8 (CO); 50.3 (COMe); 31.4 (CH2); 29.6 (CH2); 26.7 (CH2); 26.6 (CH2); 26.4 (CH2); 2.1 (MeSi); 0.9
‡
‡
(MeSi); À2.9 (MeSi); À3.0 (MeSi). EI-MS: no M peak observed, 135.1 (100, SiMe2Ph ).
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]propane (20cd; 72%). Oil. TLC (hex-
ane): Rf 0.40. IR (film): 2876, 1427, 1253, 1111. 1H-NMR (400 MHz, CDCl3): 7.82 7.77 (4m, Ph); 7.56 7.48 (6m,
Ph); 1.95 (2q, J ˆ 7.0, MeCH2); 1.91 0.86 (14m, Me, CHax, CHeq); 0.36 (3s, MeSi); 0.34 (3s, MeSi); 0.19 (3s,
MeSi); 0.18 (6s, MeSi). 13C-NMR (100 MHz, CDCl3): 139.6 (i-Ph); 138.9 (i-Ph); 134.6 (o-Ph); 134.3 (o-Ph);
129.1 (p-Ph); 128.9 (p-Ph); 127.7 (m-Ph); 127.5 (m-Ph); 80.2 (CO); 45.6 (COCH2) 32.5 (CH2); 29.6 (CH2); 26.4
(CH2); 26.4 (CH2); 26.3 (CH2); 19.6 (Me); À0.7 (MeSi); À0.8 (MeSi); À3.2 (MeSi); À3.3 (MeSi). EI-MS
‡
(C25H38OSi2; calc. 410.2461): 410.2445 (M ).
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]-2-methylpropane (20ce; 48%). Oil.
TLC (Et2O/hexane 1:99) 0.58. IR (neat): 3049 (CH), 1487 (Ph), 1253 (MeSi), 1117 (PhSi). 1H-NMR
(500 MHz, CDCl3): 7.58 (4m, o-Ph); 7.35 (6m, m- and p-Ph); 2.00 (sept., J ˆ 7, Me2CH); 1.86 (m, CH); 1.72 1.48
(5m, c-Hex); 1.13 0.83 (5m, c-Hex); 0.92 (3d, J ˆ 7, MeAMeBCH); 0.89 (3d, J ˆ 7, MeAMeBCH); 0.44 (3s,
MeAMeBSi); 0.43 (3s, MeAMeBSi); 0.42 (3s, MeAMeBSi); 0.41 (3s, MeAMeBSi). 13C-NMR (125 MHz, CDCl3):
140.9 (‡, Ph CSi); 140.5 (‡, Ph CSi); 135.0 (À, arom. CH); 133.3 (À, arom. CH); 128.9 (À, arom. CH); 128.4
(À, arom. CH); 127.5 (À, arom. CH); 127.2 (À, arom. CH); 84.8 (‡, CO); 47.2 (À, CH); 35.3 (À, CH); 30.1 (‡,
CH2); 28.4 (‡, CH2); 27.3 (‡, CH2); 26.9 (‡, CH2); 26.6 (‡, CH2); 20.6 (À, Me); 18.9 (À, Me); 1.7 (À, MeSi);
‡
1.6 (À, MeSi); 0.4 (À, MeSi); 0.3 (À, MeSi). ESI(Na )-MS (C26H40OSi2Na; calc. 447.2516): 447.2508 ([M ‡
‡
Na] ).
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]-3-methylbutane (20cf; 43%). Oil.
TLC (Et2O/hexane, 1:99) 0.40. IR (film): 2914 (s, CH), 2852s (CH), 1453m (Ph), 1264w (MeSi), 1115s
(PhSi). 1H-NMR (500 MHz, CDCl3): 7.57 7.48 (4m, Ph); 7.36 7.23 (6m, Ph); 1.79 1.47 (9m, CHeq, CH,
CH2CHMe2); 1.18 0.91 (5m, CHax); 0.78 (6d, J ˆ 6, Me2CH); 0.39 (6s, Me2Si); 0.34 (3s, MeAMeBSi); 0.33
(3s, MeAMeBSi). 13C-NMR (125 MHz, CDCl3): 140.8 (i-Ph); 139.4 (i-Ph); 134.8 (o-Ph); 133.5 (o-Ph); 128.9
(p-Ph); 128.5 (p-Ph); 127.5 (m-Ph); 127.3 (m-Ph); 81.2 (CO) 45.4 (CHCOSi); 44.7 (CH2COSi); 29.8 (CH2);
28.3 (CH2); 26.8 (CH2); 26.7 (CH2); 26.5 (CH2); 25.2 (Me2CH); 24.8 (MeAMeBCH); 24.5 (MeAMeBCH);
2.12 (MeSi); 2.08 (MeSi); À1.3 (MeSi); À1.6 (MeSi). ESI-MS (C27H42NaOSi2; calc. 461.2672): 461.2672,
‡
([M ‡ Na] ).
1-Cyclohexyl-1-dimethyl(phenyl)silyl-1-[dimethyl(phenyl)silyloxy]-4-trimethylsilyl-3-butyne (20cg; 37%).
Oil. TLC (Et2O/hexane, 1:99) 0.21. IR (film): 2928s (CH), 2852s (CH), 2172s (CꢀC), 1427m (Ph), 1249s
1
(Me3Si), 1115s (PhSi), 1054s (OÀSi), 840s (Me3Si). H-NMR (500 MHz, CDCl3): 7.59 7.50 (4m, Ph); 7.37
7.26 (6m, Ph); 2.51 (d, J ˆ 17, CHAHBCꢀC); 2.44 (d, J ˆ 17, CHAHBCꢀC); 1.90 1.56 (6m, CHeq, CH); 1.16
0.93 (5m, CHax); 0.403 (3s, MeAMeBSi); 0.397 (3s, MeAMeBSi); 0.377 (3s, MeAMeBSi); 0.371 (3s, MeAMeBSi);
0.14 (9s, Me3Si). 13C-NMR (125 MHz, CDCl3): 140.4 (i-Ph); 138.2 (i-Ph); 134.8 (o-Ph); 133.3 (o-Ph); 129.0

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Helvetica Chimica Acta Vol. 85 (2002)
(p-Ph); 128.8 (p-Ph); 127.5 (m-Ph); 127.3 (m-Ph); 104.7 (CH2CꢀCSi); 88.6 (CꢀCSi); 77.5 (CO) 46.6
(CHCOSi); 29.1 (CH2); 29.0 (CH2); 28.7 (CH2); 27.0 (CH2); 26.9 (CH2); 26.6 (CH2); 1.9 (MeSi); 1.4 (MeSi);
‡
À0.1 (Me3Si); À2.1 (MeSi); À2.2 (MeSi). ESI-MS (C29H44NaOSi3; calc. 515.2598): 515.2598, ([M ‡ Na] ).
4-Cyclopentyl-4-[dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]but-1-ene (20da; 89%). Oil. TLC
(hexane): Rf 0.42. IR (film): 2946, 1631, 1427, 1251, 1109. 1H-NMR (400 MHz, CDCl3): 7.57 (2m, Ph); 7.51
(2m, Ph); 7.37 7.30 (4m, Ph); 7.26 (2m, Ph); 5.71 (ddt, J ˆ 17.0, 10.5, 7.0, CHˆCH2); 5.04 4.96 (2m, CHˆCH2);
2.52 (ddt, J ˆ 13.5, 7.0, 1.5, CHAHBCˆC); 2.45 (ddt, J ˆ 13.5, 7.0, 1.5, CHAHBCˆC); 2.06 (m, CHCO); 1.60 1.26
(8m, 4 CH2); 0.40 (3s, MeSi); 0.39 (3s, MeSi); 0.33 (3s, MeSi); 0.33 (3s, MeSi). 13C-NMR (100 MHz, CDCl3):
140.6 (i-Ph); 138.4 (i-Ph); 135.0 (o-Ph); 134.8 (CˆCH2); 133.4 (o-Ph); 129.0 (p-Ph); 128.6 (p-Ph); 127.6 (m-Ph);
127.2 (m-Ph); 117.3 (CˆCH2); 76.8 (CO); 46.6 (CH2CˆC); 44.1 (CHCO); 28.0 (CH2); 25.8 (CH2); 25.7 (CH2);
24.9 (CH2); 2.2 (MeSi); 2.0 (MeSi); À2.3 (MeSi); À2.5 (MeSi). ESI-MS (C25H36NaOSi2; calc. 431.2202):
‡
431.2189 ([M ‡ Na] ).
4-Cyclobutyl-4-[dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]but-1-ene (20ea; 89%). Oil. TLC
(pentane): Rf 0.42. IR (film): 2946, 1631, 1427, 1251, 1109. 1H-NMR (400 MHz, CDCl3): 7.63 (2m, Ph); 7.50
(2m, Ph); 7.40 7.26 (6m, Ph); 5.64 (ddt, J ˆ 17.0, 10.0, 7.5, CHˆCH2); 5.00 (d, J ˆ 17.0, CHˆCH(Z)H(E)); 4.94 (d,
J ˆ 10.0, CHˆCH(Z)H(E)); 2.62 (m, CHCO); 2.46 (dd, J ˆ 13.5, 7.5, CHAHBCˆC); 2.30 (dd, J ˆ 13.5, 7.5,
CHAHBCˆC); 2.09 (m, CH); 1.87 (m, CH); 1.76 1.61 (3m, 3 CH); 0.43 (3s, MeSi); 0.39 (3s, MeSi); 0.30 (6s,
MeSi). 13C-NMR (100 MHz, CDCl3): 140.6 (i-Ph); 138.0 (i-Ph); 134.9 (o-Ph); 134.8 (CˆCH2); 133.4 (o-Ph);
129.1 (p-Ph); 128.8 (p-Ph); 127.6 (m-Ph); 127.3 (m-Ph); 117.0 (CˆCH2); 76.1 (CO); 42.3 (CH2CˆC); 42.3
(CHCO); 24.4 (CH2); 22.5 (CH2); 17.6 (CH2); 2.1 (MeSi); 1.9 (MeSi); À2.8 (MeSi); À3.5 (MeSi). ESI-MS
‡
(C24H34NaOSi2; calc. 417.2046): 417.2043 ([M ‡ Na] ).
2,4-Dimethyl-3-[dimethyl(phenyl)silyl]-3-[dimethyl(phenyl)silyloxy]pentane (20fe; 61%). Oil. TLC
(hexane): Rf 0.31. IR (film): 2938, 1427, 1250, 1117. 1H-NMR (400 MHz, CDCl3): 7.66 7.55 (4m, Ph); 7.43
7.37 (6m, Ph); 2.01 (2sept., J ˆ 7.0, Me2CH); 0.90 (6d, J ˆ 7.0, MeAMeBCH); 0.89 (6d, J ˆ 7.0, MeAMeBCH); 0.43
(3s, MeAMeBSi); 0.41 (3s, MeAMeBSi); 0.39 (3s, MeAMeBSi); 0.38 (3s, MeAMeBSi). 13C-NMR (100 MHz,
CDCl3): 134.7 (i-Ph); 133.4 (i-Ph); 133.0 (o-Ph); 129.2 (o-Ph); 129.0 (p-Ph); 128.5 (p-Ph); 127.7 (m-Ph); 127.2
(m-Ph); 84.4 (CO); 35.7 (Me2CH); 20.2 (MeAMeBCH); 18.9 (MeAMeBCH); 1.3 (Me2Si); 0.6 (Me2Si). EI-MS:
‡
no M observed.
1-[Dimethyl(phenyl)silyl]-2-methylpropan-1-one (34) [22] (82%), from the disilyl alcohol 13f and CCl4.
Oil. TLC (Et2O/hexane 10 :90): Rf 0.48. IR (neat): 3095 (CH), 1639 (CˆO), 1249 (CSi), 1117 (PhSi). 1H-NMR
(400 MHz, CDCl3): 7.54 (2m, Ph); 7.37 (3m, Ph); 2.89 (sept., J ˆ 7, Me2CH); 0.90 (6d, Me2CH); 0.49 (6s, Me2Si).
The Aldol Reaction: 5-Hydroxy-2-methylnonan-3-one (18) and 2,2-Dimethyl-1-[dimethyl(phenyl)silyl]-1-
[dimethyl(phenyl)silyloxy]propane (19). BuLi (1 mmol) was added to a soln. of the silyl alcohol (1 mmol) in
THF (5 ml). After 5 min, the mixture was cooled to À408. Pentanal (15; 0.12 ml, 1 mmol) and isopropyl methyl
ketone (16; 0.11 ml, 1 mmol) were added. After 2 h, the mixture was diluted with hexane, and the org. fraction
was washed with brine (20 ml), dried (MgSO4) and evaporated under reduced pressure. The 1H-NMR spectrum
contained resonances corresponding to 18 (80%, NMR) and the 19 (98%; NMR). Chromatography gave the
pure compounds as oils.
Data of 18: IR (film): 1710. 1H-NMR (400 MHz, CDCl3): 4.08 (m, CHO); 2.53 (sept., J ˆ 7, Me2CH); 2.49
(2d, J ˆ 6.5, COCH2); 1.45 1.18 (10m, CH2); 1.10 (3t, Me); 1.07 (6d, J ˆ 7, Me2CH).
1
Data of 19: TLC (hexane): Rf 0.27. IR (film): 3050, 2954, 1428, 1249, 1116. H-NMR (400 MHz, CDCl3):
7.55 7.51 (4m, Ph); 7.42 7.30 (6m, Ph); 3.47 (s, CHCO); 0.86 (9s, Me3C); 0.38 (3s, MeSi); 0.36 (3s, MeSi); 0.31
(3s, MeSi); 0.23 (3s, MeSi). 13C-NMR (100 MHz, CDCl3): 139.7 (i-Ph); 139.2 (i-Ph); 134.2 (o-Ph); 133.6 (o-Ph);
129.0 (p-Ph); 128.7 (p-Ph); 127.6 (m-Ph); 127.5 (m-Ph); 78.0 (CO); 36.5 (Me3CCO); 28.3 (Me3C); À0.4
‡
(MeSi); À0.8 (MeSi); À1.2 (MeSi); À2.6 (MeSi). EI-MS: no M peak observed.
One-Pot Brook Rearrangement Alkylation ReactionsStarting from Acid Chlorides . Typically, the acid
chloride (3.8 mmol) was added to a stirred soln. of Me2PhSiLi (1m in THF, 9.1 ml, 9.1 mmol) and toluene (9 ml)
under N2 at À788. After 1 h, alkyl halide (17 mmol) was added and the soln. was allowed to warm to r.t. After 3
18 h, the soln. was poured onto hexane (50 ml), separated, and the org. layer washed with brine (20 ml). The
org. solvent was evaporated off under reduced pressure, and the residue was chromatographed (SiO2; hexane)
to give the silyl ether. The following compounds were prepared by this method.
4-[Dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]non-1-ene (20aa; 66%). Oil. TLC (light petroleum
(b.p. 40 608)/Et2O 99.9 :0.1): Rf 0.19. IR (film): 2958, 1648, 1249, 1112. 1H-NMR (400 MHz, CDCl3): 7.59 7.57
(4m, Ph); 7.41 7.33 (6m, Ph); 5.79 (ddt, J ˆ 17.9, 9.4, 7.1, CHˆCH2); 5.01 (2m, CHˆCH2); 2.45 (dd, J ˆ 13.9, 7.2,
CHAHBCˆC); 2.41 (dd, J ˆ 13.9, 7.2, CHAHBCˆC); 1.66 1.55 (2m, CH2C(OSi)Si); 1.31 1.13 (8m, CH2); 0.86
(3t, J ˆ 7.0, Me); 0.38 (6s, MeSi); 0.37 (6s, MeSi). 13C-NMR (100 MHz, CDCl3): 140.7 (i-Ph); 138.2 (i-Ph); 135.2

Helvetica Chimica Acta Vol. 85 (2002)
3361
(CHˆCH2); 135.0 (o-Ph); 133.5 (o-Ph); 129.0 (p-Ph); 128.9 (p-Ph); 127.7 (m-Ph); 127.5 (m-Ph); 117.3
(CHˆCH2); 75.5 (C(OSi)Si); 44.0 (CH2CˆC); 39.4 (CH2); 32.7 (CH2); 24.5 (CH2); 22.7 (CH2); 14.2 (Me); 2.2
(2 MeSi); À3.1 (MeAMeBSi); À3.4 (MeAMeBSi). ESI-MS (C25H38NaOSi2; calc. 433.2359): 433.2461.
2-Methyl-3-[dimethyl(phenyl)silyl]-3-[dimethyl(phenyl)silyloxy]octane (20ae; 30%). Oil. TLC (light
petroleum (b.p. 40 608)/Et2O, 99.9 :0.1): Rf 0.23. IR (film): 2951, 1426, 1247, 1107 (PhSi). 1H-NMR
(400 MHz, CDCl3): 7.69 7.61 (4m, Ph); 7.49 7.38 (6m, Ph); 1.99 (sept., J ˆ 6.8, Me2CH); 1.76 (td, J ˆ 13.7, 5.2,
CHACHBC(OSi)Si); 1.70 (td, J ˆ 13.7, 4.7, CHACHBC(OSi)Si); 1.38-1.15 (6m, CH2); 1.00 (3d, J ˆ 6.8,
MeAMeBCH); 0.94 (3t, J ˆ 7.2, MeCH2); 0.92 (3d, J ˆ 6.8, MeAMeBCH); 0.50 (3s, MeSi); 0.48 (3s, MeSi);
0.44 (3s, MeSi); 0.43 (MeSi). 13C-NMR (100 MHz, CDCl3): 140.9 (i-Ph); 139.9 (i-Ph); 134.8 (o-Ph); 133.5 (o-
Ph); 129.0 (p-Ph); 128.7 (p-Ph); 127.6 (m-Ph); 127.4 (m-Ph); 79.7 (C(OSi)Si); 37.7 (CH2C(OSi)Si); 34.1
(Me2CH); 32.7 (CH2); 24.2 (CH2); 22.6 (CH2); 19.5 (MeAMeBCH); 17.7 (MeAMeBCH); 14.2 (MeCH2); 2.3
‡
(MeSi); 2.0 (MeSi); À1.5 (MeSi); À1.81 (MeSi). ESI-MS (C29H48OSi2; calc. 435.2517): 435.2515 ([M ‡ Na] ).
4-[Dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]tridec-1-ene (20ba; 41%). Oil. TLC (light petro-
leum (b.p. 40 608)): Rf 0.25. IR (film): 2919, 1615, 1115. 1H-NMR (400 MHz, CDCl3): 7.57 7.54 (4m, Ph);
7.37 7.26 (6m, Ph); 5.77 (ddt, J ˆ 17.8, 9.4, 7.2, CHˆCH2); 4.99 (2m, CHˆCH2); 2.44 (dd, J ˆ 14.0, 7.2,
CHAHBCˆC); 2.39 (dd, J ˆ 14.0, 7.2, CHAHBCˆC); 1.66 1.55 (2m, CH2C(OSi)Si); 1.32 1.14 (14m, CH2); 0.92
(3t, J ˆ 6.8, Me); 0.363 (6s, MeSi); 0.357 (6s, MeSi). 13C-NMR (100 MHz, CDCl3): 140.7 (i-Ph); 138.1 (i-Ph);
135.1 (CHˆCH2); 134.8 (o-Ph); 133.4 (o-Ph); 129.0 (p-Ph); 128.8 (p-Ph); 127.6 (m-Ph); 127.4 (m-Ph); 117.2
(CHˆCH2); 75.4 (C(OSi)Si); 43.9 (CH2CˆC); 39.3 (CH2); 31.9 (CH2); 30.3 (CH2); 29.52 (CH2); 29.47 (CH2);
29.3 (CH2); 24.6 (CH2); 22.7 (CH2); 14.1 (Me); 2.0 (2 MeSi); À3.3 (MeAMeBSi); À3.5 (MeAMeBSi). ESI-MS
‡
(C29H46ONaSi2; calc. 489.3087): 489.3107 ([M ‡ Na] ).
4-Cyclohexyl-4-[dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]but-1-ene (20ca; 98%). Identical
1
(TLC, H-NMR) to the sample prepared earlier.
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]-2-methylpropane (20ce; 65%). Iden-
tical (TLC, 1H-NMR) to the sample prepared earlier.
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-1-[dimethyl(phenyl)silyloxy]-3-methylbutane (20cf; 45%). Identi-
cal (TLC, 1H-NMR) to the sample prepared earlier.
4-[Dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]-5-methylhex-1-ene (20fa; 75%). Oil. TLC
(hexane/Et2O 99 :1): Rf 0.30. IR (film): 2959, 1637, 1427, 1252, 1115. 1H-NMR (400 MHz, CDCl3): 7.67 7.58
(4m, Ph); 7.43 7.31 (6m, Ph); 5.85 (ddt, J ˆ 17.5, 9.5, 7.0, CHˆCH2); 5.12 5.05 (2m, CHˆCH2); 2.58 (2dd, J ˆ
7.0, 1.0, CH2CˆC); 1.98 (sept., J ˆ 7.0, Me2CH); 0.96 (3d, J ˆ 7.0, MeAMeBCH); 0.93 (3d, J ˆ 7.0, MeAMeBCH);
0.47 (3s, MeSi); 0.46 (3s, MeSi); 0.44 (6s, MeSi). 13C-NMR (100 MHz, CDCl3): 140.7 (i-Ph); 138.9 (i-Ph); 135.0
(CˆCH2); 134.7 (o-Ph); 133.4 (o-Ph); 129.0 (p-Ph); 128.7 (p-Ph); 127.6 (m-Ph); 127.4 (m-Ph); 117.6 (CˆCH2);
79.0 (CO); 42.0 (CH2CˆC); 31.6 (Me2CH); 19.3 (MeAMeBCH); 17.9 (MeAMeBCH); 2.2 (MeSi); 2.0 (MeSi);
‡
‡
‡
À1.8 (MeSi). EI-MS: no M peak observed, 247.2 (40, [M À SiMe2Ph] ),135.1 (100, SiMe2Ph ).
2-[Dimethyl(phenyl)silyl]-2-[dimethyl(phenyl)silyloxy]-3-methyl-1-phenylbutane (20fb; 50%). Oil. TLC
(hexane): Rf 0.23. IR (film): 2935, 1602, 1589, 1426, 1250, 1114. 1H-NMR (400 MHz, CDCl3): 7.55 (2m, Ph); 7.46
(2m, Ph); 7.41 7.12 (11m, Ph); 3.09 (2 br. s, CHAHBPh); 2.09 (1sept., J ˆ 6.5, Me2CH); 1.02 (3d, J ˆ 6.5,
MeAMeBCH); 0.96 (3d, J ˆ 6.5, MeAMeBCH); 0.36 (3s, MeSi); 0.32 (6s, MeSi), 0.20 (3s, MeSi). 13C-NMR
(100 MHz, CDCl3): 140.9 (i-PhSi); 139.0 (i-PhSi); 137.7 (i-Ph); 134.9 (o-PhSi); 133.5 (o-PhSi); 131.5 (o-Ph);
128.9 (p-PhSi); 128.6 (p-PhSi); 127.8, 127.5, 127.3 (3 m-Ph); 126.3 (p-Ph); 81.2 (CO); 42.0 (PhCH2); 33.9
(CHCO); 20.0 (MeAMeBCH); 19.2 (MeAMeBCH); 2.2 (MeSi); 1.7 (MeSi); À1.5 (MeSi); À2.0 (MeSi). EI-MS:
‡
‡
‡
‡
no M peak observed, 297.2 (41, [M À SiMe2Ph] ), 135.1 (100, SiMe2Ph ).
2-[Dimethyl(phenyl)silyl]-2-[dimethyl(phenyl)silyloxy]-3-methylbutane (20fc; 62%). Oil. TLC (hexane-
Et2O, 99 :1): Rf 0.37. IR (film): 2909, 1427, 1250, 1110. 1H-NMR (400 MHz, CDCl3): 7.72 7.63 (4m, Ph); 7.48
7.37 (6m, Ph); 1.91 (1sept., J ˆ 7.0, Me2CH); 1.42 (3s, COSiMe); 0.96 (3d, J ˆ 7.0, MeAMeBCH); 0.91 (3d, J ˆ 7.0,
MeAMeBCH); 0.48 (3s, MeSi); 0.47 (6s, MeSi); 0.42 (3s, MeSi). 13C-NMR (100 MHz, CDCl3): 140.6 (i-Ph); 138.9
(i-Ph); 134.6 (o-Ph); 133.3 (o-Ph); 128.9 (p-Ph); 128.7 (p-Ph); 127.5 (m-Ph); 127.5 (m-Ph); 78.5 (CO); 32.3
(Me2CH); 21.6 (COMe); 19.3 (MeAMeBCH); 17.9 (MeAMeBCH); 2.1 (MeSi); 1.8 (MeSi); À1.9 (MeSi); À2.1
‡
(MeSi). EI-MS (C12H32OSi2; calc. 356.1992): 356.2004 (M ).
6-Bromo-3-[dimethyl(phenyl)silyl]-3-[dimethyl(phenyl)silyloxy]-2-methylhexane (20ff). With a 5-fold
excess of 1,3-dibromopropane, followed by ethanolysis (40%), together with some silyl ether. TLC (hexane/
Et2O 90 :10): Rf 0.54. IR (film): 3600, 2957, 1427, 1254, 1118, 1051. 1H-NMR (400 MHz, CDCl3): 7.65 (2m, Ph);
7.40 7.33 (3m, Ph); 3.81 (1m, CHAHBBr); 3.47 (m, CHAHBBr); 1.98 1.72 (4m, 2 CH2); 1.58 (m, Me2CH); 0.85
(3d, J ˆ 7.0, MeAMeBCH); 0.85 (3d, J ˆ 7.0, MeAMeBCH); 0.41 (3s, MeAMeBSi), 0.40 (3s, MeAMeBSi). 13C-NMR
(100 MHz, CDCl3): 138.5 (i-Ph); 134.5 (o-Ph); 128.7 (p-Ph); 127.4 (m-Ph); 82.4 (CO); 68.7 (CH2Br); 35.5

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Helvetica Chimica Acta Vol. 85 (2002)
(CHCO); 29.0 (CH2); 27.3 (CH2); 19.0 (MeAMeBCH); 17.8 (MeAMeBCH); À3.2 (MeSi); À3.4 (MeSi). EI-MS:
‡
no M peak observed.
4-[Dimethyl(phenyl)silyl]-4-[dimethyl(phenyl)silyloxy]-5,5-dimethylhexene (20ja; 98%). Oil. TLC (hex-
ane): Rf 0.38. IR (film): 2956, 1427, 1254, 1115, 1050. 1H-NMR (400 MHz, CDCl3): 7.62 (2m, Ph); 7.55 (2m, Ph);
7.41-7.24 (6m, Ph); 6.01 (ddt, J ˆ 17.5, 10.5, 7.0, CH2CHˆCH2); 5.08 (br. d, J ˆ 17.5, CHˆCHEH(Z)); 5.01 (br. d,
J ˆ 10.5, CHˆCH(E)HZ); 2.70 (2d, J ˆ 7.0, CHAHBCˆC); 0.86 (9s, Me3C); 0.43 (3s, MeSi); 0.40 (9s, MeSi).
13C-NMR (100 MHz, CDCl3): 140.4 (i-Ph); 140.0 (i-Ph); 136.8 (CˆCH2); 135.1 (o-Ph); 133.5 (o-Ph); 129.0 (p-
Ph); 128.6 (p-Ph); 127.6 (m-Ph); 127.4 (m-Ph); 116.2 (CˆCH2); 82.8 (CO); 43.3 (CH2CˆC); 40.3 (Me3CCO);
‡
27.9 (Me3C); 2.4 (MeSi); 1.9 (MeSi); 0.2 (MeSi); À0.3 (MeSi). EI-MS: no M observed.
2-[Dimethyl(phenyl)silyl]-2-[dimethyl(phenyl)silyloxy]-3,3-dimethyl-1-phenylbutane (20jb; 82%). Oil.
TLC (hexane): Rf 0.27. IR (film): 3068, 2956, 1427, 1257, 1114. 1H-NMR (400 MHz, CDCl3): 7.70 (2m, Ph);
7.62 (2m, Ph); 7.46 7.19 (11m, Ph); 3.32 (d, J ˆ 14.0, PhCHAHB); 3.26 (d, J ˆ 14.0, PhCHAHB); 0.84 (9s, Me3C);
0.60 (3s, MeSi); 0.59 (3s, MeSi); 0.39 (3s, MeSi); 0.34 (3s, MeSi). 13C-NMR (100 MHz, CDCl3): 140.5 (i-PhSi);
140.4 (i-PhSi); 139.4 (i-Ph); 135.1 (o-PhSi); 133.7 (o-PhSi); 131.3 (o-Ph); 129.2 (p-PhSi); 128.5 (p-PhSi); 127.7,
127.6, 127.3 (3 m-Ph); 126.1 (p-Ph); 85.8 (CO); 43.8 (PhCH2); 40.6 (Me3CCO); 28.5 (Me3C); 2.6 (MeSi); 2.4
‡
‡
(MeSi); 0.4 (MeSi); 0.4 (MeSi). EI-MS: no M peak observed, 312.0 (50, [M ‡ H À SiMe2Ph] ), 135.1 (100,
‡
SiMe2Ph ).
[(1-Cyclohexyl(ethenyl)oxy]dimethyl(phenyl)silane (28). Prepared from the acid chloride 12c and CH2Br2
after transferring the silyllithium reagent from THF into Et2O and with pentane in place of toluene as the
solvent. The silyl enol ether was characterised after desilylation as 1-cyclohexylethan-1-one (29).
3-[Dimethyl(phenyl)silyl]-3-[dimethyl(phenyl)silyloxy]-4-phenylbut-1-ene (30; 86%). Prepared from
PhCOCl and characterised after desilylation as 1-phenyl-1-[dimethyl(phenyl)silyl]but-3-en-ol (31).
4-[Dimethyl(phenyl)silyloxy]-4-phenylhepta-1,6-diene (32). Prepared from PhCOCl and characterised
after desilylation as hepta-1,6-dien-4-ol (33).
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]but-3-en-1-ol (22). HCl (10m, 0.5 ml, 5 mmol) and 20ca (0.57 g,
1.0 mmol) were stirred in MeOH (5 ml) for 2 h, which was probably not optimal. Most of the solvent was
removed under reduced pressure, the residue was poured into H2O and extracted with Et2O (3 Â 20 ml). The
extract was washed with brine (20 ml), dried (MgSO4), and the solvent removed under reduced pressure. The
residue was chromatographed (SiO2; hexane/Et2O 9 :1) to give 22 (59%) as an oil. TLC (light petroleum (b.p.
40 608)/Et2O 9 :1): Rf 0.19. IR (film): 3564 (br., OH), 2934 (CH), 1634 (CˆC), 1427 (Ph), 1248 (SiÀMe),
1115 (SiPh). 1H-NMR (400 MHz, CDCl3): 7.59 (2m, o-Ph); 7.40 7.29 (3m, m- and p-Ph); 5.80 (ddt, J ˆ 17.5,
10.0, 7.6, CHˆCH2); 5.10 5.01 (2m, CHˆCH2); 2.39 (dd, J ˆ 14.0, 7.0, CHACHBCˆC); 2.33 (dd, J ˆ 14.0, 7.0,
CHACHBCˆC); 1.77 1.46 (6m, CHC(OSi)Si, 5 CHeq); 1.18 0.95 (5m, CHax); 0.40 (6s, Me2Si). 13C-NMR
(100 MHz, CDCl3): 138.1 (i-Ph); 134.7 (o-Ph); 134.3 (CHˆCH2); 128.9 (p-Ph); 127.6 (m-Ph); 118.4 (CˆCH2);
71.2 (CO); 46.2 (CHCO); 39.9 (CH2CˆC); 28.6 (CH2); 27.7 (CH2); 26.9 (CH2); 26.9 (CH2); 26.7 (CH2); À2.1
‡
(Me2Si). ESI-MS (C18H28NaOSi; calc. 311.1807): 311.1800 ([M ‡ Na] ).
1-Cyclohexylbut-3-en-1-one (23). The alcohol 22 (0.10 g, 0.3 mmol) in CH2Cl2 (0.5 ml) was stirred with PCC
(0.12 g, 0.6 mmol) in CH2Cl2 (1 ml) for 18 h. The mixture was passed through a silica pad, and the solvent was
removed under reduced pressure. The residue was chromatographed (SiO2; CH2Cl2/pentane 3 :7) to give 23
(83%). TLC (light petroleum (b.p. 30 408)/CH2Cl2 4 :6): Rf 0.25. IR (film): 2939, 1708, 1639. 1H-NMR
(400 MHz; CDCl3): 5.89 (ddt, J ˆ 17.1, 10.2, 6.9, CHˆCH2); 5.12 (dq, J ˆ 10.2, 1.4, CHˆCHZCH(E)); 5.08 (dq,
J ˆ 17.1, 1.4, CHˆCH(Z)CHE); 3.18 (2dt, J ˆ 6.9, 1.3, CH2CHˆCH2); 2.36 (tt, J ˆ 10.7, 3.0 CHCO); 1.82 1.65
(5m, CHeq); 1.33 1.15 (5m, CHax). 13C-NMR (100 MHz, CDCl3): 211.6 (CˆO); 131.0 (CHˆCH2); 118.3
(CHˆCH2); 50.4 (CHCO); 45.5 (CH2CO); 28.4 (2 CH2); 25.8 (2 CH2); 25.6 (2 CH2).
1-Cyclohexyl-1-[dimethyl(phenyl)silyl]-3-methylbutan-1-ol (24). The silyl ether 20cf (0.336 g, 0.77 mmol)
was stirred with TBAF (1m in THF, 2.3 ml, 2.3 mmol) at r.t. for 4 h. The mixture was diluted with distilled H2O
and CH2Cl2, and the org. phase was passed through a silica pad, and washed with Et2O. The solvent was
evaporated under reduced pressure to give the crude product as a colourless oil (0.189 g, 0.62 mmol, 81%).
1H-NMR (400 MHz, CDCl3): 7.62 7.57 (2m, Ph); 7.41 7.36 (3m, Ph); 1.82 1.60 (10m, CHeq, CH, CHAHB,
Me2CH, OH); 1.21-1.00 (5m, CHax); 0.93 (3d, J ˆ 7, MeAMeBCH); 0.89 (3d, J ˆ 7, MeAMeBCH); 0.30 (6s,
Me2Si).
1-Cyclohexyl-3-methylbutan-1-one (25). The alcohol 24 (0.189 g, 0.62 mmol) was stirred in CH2Cl2 (5 ml)
with PCC (0.530 g, 2.5 mmol) for 18 h at r.t. The mixture was passed through a silica pad, and washed with
CH2Cl2. The solvent was evaporated under reduced pressure to give 25 [34] as a colourless oil (0.087 g, 83%).
TLC (light petroleum (b.p. 30 408)): Rf 0.57 (staining with 2,4-dinitrophenylhydrazine). 1H-NMR (400 MHz,
CDCl3): 2.28 (3m, CHCO, CH2CO); 2.12 (nonet., J ˆ 7, Me2CH); 1.82 1.59 (5m, CHeq,); 1.18 0.91 (5m, CHax);

Helvetica Chimica Acta Vol. 85 (2002)
3363
0.87 (6d, J ˆ 7, Me2CH). 13C-NMR (400 MHz, CDCl3): 213.2 (CO); 50.7 (CHCO); 49.3 (CH2CO); 28.0 (CH2);
‡
25.5 (CH2); 25.3 (CH2); 22.3 (Me2CH); 21.95 (Me2C). EI-MS (C11H20O; calc. 168.1514): 168.1520, (M ).
1-Cyclohexyl-2-methylpropanol (26). The silyl ether 20ce (2.5 g, 6 mmol) in THF (1 ml) was stirred with
TBAF (4.0 g, 15 mmol) in THF (20 ml) at r.t. for 18 h. The THF was evaporated off, distilled H2O (20 ml) was
added to the residue, which was extracted with CH2Cl2 (5 Â 20 ml). The combined org. layers were washed with
brine (20 ml), dried (MgSO4) and concentrated under reduced pressure to give the crude 26 (2.5 g). Part of the
residue (0.5 g) was purified by flash column chromatography to give 26 [35] (0.172 g, 95%). The crude mixture
was used directly in the oxidation below. TLC (Et2O/hexane 10 :90): Rf 0.24. IR (CHCl3): 3456 (OH), 2926
(CH). 1H-NMR (400 MHz, CDCl3): 4.01 (t, J ˆ 5, CHOH); 1.75 (sept., d, J ˆ 7, 5, Me2CH); 1.84 (m, CH); 1.81
1.52 (5m, c-Hex); 1.42 0.91 (5m, c-Hex); 0.90 (3d, J ˆ 7, MeAMeBCH); 0.88 (3d, J ˆ 7, MeAMeBCH).
1-Cyclohexyl-2-methylpropan-1-one (27). The crude alcohol 20ce (2.4 mmol) in CH2Cl2 was stirred with
PCC (10 mmol) for 18 h at r.t. The mixture was diluted with pentane (20 ml), passed through a silica pad,
washed with CH2Cl2 (20 ml), and the solvent was carefully evaporated under reduced pressure. The residue was
purified by flash column chromatography (CH2Cl2/light petroleum (b.p. 30 408) 30 :70) to yield 27 (2.1 mmol,
88% over two steps from 20ce). TLC (Et2O/hexane 20 :80): Rf 0.40. IR (neat): 2930 (CÀH), 1706 (CˆO).
1H-NMR (400 MHz, CDCl3): 2.74 (sept., J ˆ 7, Me2CH); 2.49 (tt, J ˆ 11, 3, CH); 1.77 (4m, c-Hex); 1.67 (m, c -
Hex); 1.42-1.13 (5m, c-Hex); 1.05 (6d, J ˆ 7, Me2CH).
1-Cyclohexyl ethan-1-one (29). HCl (10m, 0.5 ml, 5 mmol) and crude 28 (1.0 mmol) were stirred in MeOH
(10 ml) at r.t. for 18 h. Distilled H2O (30 ml) was added to the mixture, which was extracted with CH2Cl2 (3 Â
20 ml). The combined org. layers were washed with brine (10 ml), dried (MgSO4), and the solvent was carefully
removed under reduced pressure to give 29 [36] as a yellow liquid (76% from cyclohexanecarbonyl chloride).
1
TLC (Et2O/hexane 10 :90): Rf 0.30. IR (neat): 1711 (CˆO). H-NMR (400 MHz, CDCl3): 2.31 (tt, J ˆ 11, 3);
2.11 (3s, Me); 1.89 1.49 (5m, c-Hex); 1.35-0.81 (5m, c-Hex).
1-[Dimethyl(phenyl)silyl]-1-phenylbut-3-en-1-ol (31). HCl (10m, 0.5 ml, 5 mmol) and 30 were stirred in
MeOH at r.t. for 3 h, and MeOH was removed at reduced pressure. The residue was dissolved in CH2Cl2 (20 ml),
washed with distilled H2O (10 ml), brine (10 ml), dried (MgSO4) and concentrated under reduced pressure. The
residue was purified by flash column chromatography (Et2O/hexane 5 :95) to yield 31 (80% over two steps from
PhCOCl) as an oil. TLC (Et2O/hexane 10 :90) Rf 0.28. IR (neat): 3555 (OH), 2926 (CH), 1638 (CˆC), 1493
(Ph), 1255 (MeSi), 1116 (PhSi). 1H-NMR (400 MHz, CDCl3): 7.39 (3m, m- and p-Ph); 7.32 (2m, o-Ph); 7.22 (2m,
m-Ph); 7.12 (3m, o- and p-Ph); 5.43 (dddd, J ˆ 17, 11, 8, 5, CHˆCH2); 5.09 (2m, ˆCH2); 2.98 (2ddt, J ˆ 14, 5, 1,
ˆ CHCHAHB); 2.51 (2dd, J ˆ 14, 8, ˆ CHCHAHB); 1.86 (br. s, OH); 0.30 (3s, MeAMeBSi); 0.24 (3s,
MeAMeBSi).13C-NMR (100 MHz, CDCl3): 146.6 (‡, Ph); 137.4 (‡, CSi); 136.5 (À, Ph); 134.2 (À, Ph); 131.0 (À,
Ph); 129.4 (À, Ph); 129.2 (À, Ph); 129.1 (À, Ph); 126.9 (À, CHˆCH2); 121.7 (‡, CHˆCH2); 72.4 (‡, CO); 43.1
‡
‡
(‡, CH2); À3.8 (À, MeSi); À4.4 (À, MeSi). ESI(Na )-MS: no M observed.
4-Phenylhepta-1,6-dien-4-ol (33). The silyl ether 32 (0.5 mmol) was stirred with TBAF in THF (1.5 ml,
1.0m) at r.t. for 3 h, diluted with CH2Cl2 (10 ml), washed with distilled H2O (10 ml), brine (10 ml), dried
(MgSO4) and concentrated under reduced pressure. The residue was purified by flash column chromatography
(Et2O/hexane 10 :90) to give 33 [37] (91% over 2 steps) as an oil. TLC (Et2O/hexane 50 :50): Rf 0.30. IR (neat):
3511 (OH), 3069 (CH), 1634 (CˆC), 1469 (Ph), 1246 (MeSi), 1114 (PhSi). 1H-NMR (400 MHz, CDCl3): 7.42
7.15 (5m, Ph); 5.61 (2dddd, J ˆ 14, 10, 8, 6, CHˆCH2); 5.11 (4m, CHˆCH2); 2.70 (2ddt, J ˆ 14, 6, 1,
ˆCHCHAHB); 2.53 (2dd, J ˆ 14, 8, ˆ CHCHAHB); 2.19 (br., OH).
Methyl (Cyclohexyl)[dimethyl(phenyl)silyl][dimethyl(phenyl)silyloxy]methanesulfite (35; 70%). Oil. Pre-
pared by the same method as for the reactions with alkyl halides, except that the electrophile was methane
chlorosulfite. TLC (hexane/Et2O, 96 :4): Rf 0.06. IR (film): 2932, 2854, 1427, 1254, 1189, 1109. 1H-NMR
(400 MHz, CDCl3): 7.67 7.62 (4m, Ph); 7.40 7.33 (6m, Ph); 3.75 (3s, MeO); 2.19 2.07 (2m, CHax); 1.97 1.92
(m, CHaxCO); 1.75 1.57 (3m, CHax); 1.25 1.10 (3m, CHeq); 1.05 0.92 (2m, CHeq); 0.55 (3s, MeSi); 0.50 (3s,
MeSi); 0.37 (3s, MeSi), 0.33 (3s, MeSi). 13C-NMR (100 MHz, CDCl3): 137.9 (i-Ph); 137.8 (i- Ph); 135.4 (o-Ph);
135.3 (o-Ph); 129.5 (p-Ph); 129.5 (p-Ph); 127.5 (m-Ph); 127.5 (m-Ph); 89.7 (CO); 47.8 (MeO); 45.9 (CHCO);
31.5 (CH2); 31.1 (CH2); 26.7 (CH2); 26.7 (CH2); 26.5 (CH2); 0.5 (MeSi); 0.4 (MeSi); À0.5, À0.6 (MeSi). EI-MS
‡
‡
‡
(C24H36O3SSi2; calc. 460.1924): 460.1945 (M ), 460.2 (11, M ), 381.2 (20, [M À SO2Me] ), 135.1 (100,
‡
SiMe2Ph ).

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Received May 15, 2002