Silyl-cupration of an acetylene followed by ring-formation

Article abstract of DOI:10.1039/a809813a

The acetylenes 1a-e undergo silyl-cupration followed by cyclisation, the acetylenes 1f-1h react with the silyl-cuprate reagent more rapidly at the alternative electrophilic site, and the acetylenes 1i, 1j and 17 give relatively low yields of cyclic produc

Full text of DOI:10.1039/a809813a

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Silyl-cupration of an acetylene followed by ring-formation
Ian Fleming* and Eduardo Martínez de Marigorta
Department of Chemistry, Lensfield Road, Cambridge, UK CB2 1EW
Received (in Cambridge) 16th December 1998, Accepted 22nd December 1998
The acetylenes 1a–e undergo silyl-cupration followed by cyclisation, the acetylenes 1f–1h react with the silyl-cuprate
reagent more rapidly at the alternative electrophilic site, and the acetylenes 1i, 1j and 17 give relatively low yields of
cyclic products amongst others. Ring-formation is, unusually, a not particularly favourable pathway.
adding the substrates 1 to the bissilylcuprate reagent 2. The
most simple of these (Scheme 2) showed that the acetylene was
Introduction
We established in a series of papers between 19781 and 1995
thatourphenyldimethylsilylcupratereagent22 reactswithacetyl-
OTs
enes,3 allenes,4 allylic acetates5 and a variety of αβ-unsaturated
enone systems.6 Others have established that the same or similar
i
silyl-cuprate reagents react with acid chlorides,7,8 allylic chlor-
SiMe2Ph
ides,9 a vinyl iodide,10 epoxides,8,11 a primary alkyl bromide,11 an
iminium ion,12 a vinyl sulfone,13 vinyl sulfoxides,14 and a few
1a
4a 75%
other, probably less general, functional groups.15 However, we
had almost no indication what the relative reactivity of these
substrates might be. Allyl crotonate gave conjugate addition of
the silyl-cuprate reagent to the enone system and only a little
crotonic acid from cleavage of the allyl ester function,16 but allyl
cinnamate gave largely cinnamic acid,17 from which we deduce
that αβ-unsaturated esters and primary allylic acetates are
comparable in reactivity. The only other hint was that Oshima
had observed 3–6-membered ring-formation in the copper-
catalysed addition of PhMe2SiMgMe to terminal acetylenes
carrying a range of primary and secondary methanesulfonate
and tosylate (toluene-p-sulfonate) groups, in which the first step
had been the attack on the acetylene group rather than on the
carbon carrying the sulfonate groups.18 We already knew that
the reaction with a terminal acetylene3 was one of the easiest to
do, and that it took place at low temperature. We chose, there-
fore, to investigate the reaction of a terminal acetylene 1
attached by a chain of three or four carbon atoms to several of the
other groups, labelled Eϩ (Scheme 1). We hoped that, when the
O
OH
i
SiMe2Ph
1b
4b 75%
HO
O
i
SiMe2Ph
1c
4c 83%
Scheme 2 Reagents: i, (PhMe2Si)2CuCNLi2, THF, Ϫ78 ЊC→room
temp., normal addition.
more reactive than the toluene-p-sulfonate, the ketone, and
the epoxide groups in the substrates 1a–1c, giving the cyclo-
pentanes 4a–4c as the only identifiable products.
The epoxides 1d and 1e were only slightly more complicated
(Scheme 3), giving a mixture of regioisomers 4da and 4db in the
former case, and a mixture of three products in the latter: the
major product was the six-membered ring cyclisation product
4e, but there were minor amounts of the product 5 of silyl-
cupration without cyclisation, and of the product 6 of reaction
at both sites. The proportion of reaction taking place at both
sites should be reduced by inverse addition, although this is
somewhat less convenient to carry out, and runs a small risk
of losing, through decomposition, some of the silyl-cuprate
reagent as it is transferred by cannula into the cold solution of
the substrate. However, inverse addition in the reaction with the
epoxide 1e did not increase the amount of the cyclic product 4e:
the three products were formed in yields of 44%, 41% and 10%,
respectively, raising the proportion of reaction taking place
without cyclisation, possibly because the intermediate 3 is
generated in a less scrupulously dry medium.
In contrast, the aldehyde 1f and the allylic acetates 1g and 1h
gave no cyclic product (Scheme 4). When we used one equiv-
alent of the bissilylcuprate 2 on the aldehyde 1f, the only recog-
nisable product, apart from some recovered aldehyde, was the
alcohol 7 (45%) from attack at both sites. With two equivalents
of the cuprate, the yield of this product was quite good (70%).
Using inverse addition, we were able to isolate a small amount
of the alcohol 8, showing that the aldehyde group was more
(PhMe2Si)2CuCN Li2
E+
E+
2
–
Cu SiMe2Ph
SiMe2Ph
1
3
E
SiMe2Ph
4
Scheme 1
acetylene was the site of initial attack, carbocyclic rings 4 might
be formed from an intermediate vinylcuprate 3, and, when it
was not, we would at least learn something about the relative
reactivity of the various groups. We reported some of our work
in a preliminary communication,19 and we now report it in full.
Results and discussion
We begin with the reactions carried out in the easier way, by
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900
889

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OH
SiMe2Ph
SiMe2Ph
OH
SiMe2Ph
O
4da 64%
2
CHO
7
45% from 1 equiv. 2
70% from 2 equiv. 2
23% from 1 equiv. 2
and inverse addition
2
+
OH
1d
1f
+
SiMe2Ph
OH
4db 20%
SiMe2Ph
OH
O
7% from 1 equiv. 2
and inverse addition
8
2
SiMe2Ph
1e
4e 65%
SiMe2Ph
SiMe2Ph
OH
SiMe2Ph
SiMe2Ph
O
+
+
9
64% from 1 equiv. 2
88% from 2 equiv. 2
0% from 1 equiv. 2
and inverse addition
SiMe2Ph
5 12%
Scheme 3
6 7%
2
OAc
+
reactive than the acetylene group. Similarly, the allylic acetates
1g and 1h, with either one or two equivalents of the cuprate
reagent, gave largely the allylsilanes 9 and 11, as mixtures of
geometrical isomers, from attack at both sites. Using inverse
addition, we were able to isolate the mixtures of allylsilanes 10
and 12, respectively, in which no reaction had occurred at the
acetylene groups, showing that allylic acetates are also more
reactive than a terminal acetylene. In the reactions with the
allylic acetates, we also obtained substantial amounts of
unchanged starting material, but there was no sign in any of
these experiments of any significant quantities of cyclic prod-
ucts. There is therefore little hope of using an aldehyde or an
allylic acetate for ring formation by this method.
SiMe2Ph
1g
51% from 1 equiv. 2
and inverse addition
10
SiMe2Ph
SiMe2Ph
The αβ-unsaturated ester 1i and the acetylene 1j each gave
some cyclisation (Scheme 5). Because the former might be one
of the more useful synthetic reactions we carried it out under a
number of different conditions and with a number of silyl-
cuprate reagents. The cyclopentane 4i was present in the prod-
uct mixture of every variant that we tried, except when we used
two equivalents of the cuprate 2 and normal addition, when we
obtained the product 13 of addition at both sites, together with
its regioisomer 14 having the silyl group attached to the internal
carbon atom of the acetylene. The best yield of the cyclisation
product 4i was a mere 30% (60% based on starting material
consumed) obtained using one equivalent of a 1:1 silyl-cuprate
reagent and inverse addition, which this time did increase the
proportion of cyclisation. It appears that the unsaturated ester
group is nearly as reactive as the acetylene group, as shown by
the formation of some of the product 15 of reaction only at that
site. A similar cyclisation has been achieved with a stannyl
cuprate.20
11
51% from 1 equiv. 2
68% from 2 equiv. 2
47% from 1 equiv. 2
and inverse addition
2
OAc
+
SiMe2Ph
1h
20% from 1 equiv. 2
and inverse addition
12
Scheme 4
reaction. We were not too surprised therefore that cyclisation
might not always occur, even when the acetylene was the first
group to be attacked by the silyl-cuprate reagent.
Why do we see here such a limited range of substrates
undergoing cyclisation, when five-membered ring formation is
normally faster than intermolecular reactions? We believe that
silyl-cuprates are inherently more reactive than carbon-based
cuprates, based on our observation that a mixed cuprate, having
one silyl group and one alkyl, transfers only the silyl group to
any of the usual substrates.21 In consequence, the intramolecu-
larity of the cyclisation step 3→4 must compete with the
relatively high reactivity of silyl-cuprates in the intermolecular
Because we foresaw that cyclisation might not be easy, we had
incorporated geminal dimethyl groups in all the substrates 1
above, in order to benefit from the Thorpe–Ingold effect. In
Oshima’s reaction, similar to 1a→4a but with no geminal
dimethyl group, cyclisation had been easy, but we reasoned that
this was an especially favourable situation. That it had been a
wise precaution for our other reactions became evident when
we repeated the second of our most successful reactions with-
out that advantage. In contrast to the ketone 1b, the ketone 17
890
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900

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E
CO2Me
SiMe2Ph
SiMe2Ph
4
4i
30% from 1 equiv. i
and inverse addition
+
E+
E+
CO2Me
2
–
Cu SiMe2Ph
SiMe2Ph
SiMe2Ph
1
CO2Me
SiMe2Ph
3
2
43% from 2 equiv. 2
13
2
2?
or intramolecular
SiMe2Ph
+
CO2Me
or i
SiMe2Ph
SiMe2Ph
SiMe2Ph
E
E
2
1i
SiMe2Ph
22% from 2 equiv. 2
14
20
21
+
CO2Me
Scheme 7
SiMe2Ph
(Scheme 7). In the one, the silyl-cuprate reagent attacks the
group Eϩ to give an intermediate 20 faster than it attacks the
acetylene to give an intermediate 3. This is the route we believe
is followed in the reactions with the aldehyde 1f, the allylic
acetates 1g and 1h, and perhaps with the unsaturated ester 1i. In
the other, those substrates reacting first at the acetylene group,
such as the epoxide 1e, perhaps the unsaturated ester 1i, and the
bisacetylene 1j, evidently do not always undergo cyclisation
3→4 faster than the delivery of a silyl group to the group Eϩ. In
the latter case, the second silyl group might be delivered to the
group Eϩ by intermolecular attack on the intermediate 3 or
by intramolecular delivery of the silyl group already present in
the mixed cuprate functionality. With simple acetylenes, the
addition of electrophiles to the first-formed product of silyl-
cupration, analogous to 3, has always given the products of
carbon–carbon bond formation,3
However, other mixed cuprates, prepared from one equivalent
of the silyllithium reagent and one equivalent of an alkyllithium
reagent, regularly give products of silicon–carbon bond form-
ation.21 We have commented before on this unexplained dis-
crepancy, and hoped that some of the work in this paper might
throw light upon it. Certainly, we cannot discount the possibil-
ity here of intramolecular delivery of the silyl group in the step
3→21, which might explain the inefficiency of the cyclisation.
If 3→21 is a bimolecular reaction, inverse addition ought to
reduce the ratio 21:4 when compared with normal addition.
Alternatively, if the silyl group is transferred intramolecularly,
the ratio 21:4 should be unaffected. In the reaction using
inverse addition with the unsaturated ester 1i, the ratio
decreased, which implied that intramolecular delivery is not
occurring. In one other reaction, 1e→4e–6, the proportion of
bis-adduct was essentially the same using inverse addition, but
that could simply have been a consequence of protonation,
before the second attack took place.
15
5% from 1 equiv. i
and inverse addition
SiMe2Ph
4j
16% from 1 equiv.2
and inverse addition
2
+
SiMe2Ph
SiMe2Ph
similar to the step 3→4.
1j
16
43% from 1 equiv. 2
and inverse addition
Scheme 5 Reagent: i, PhMe2SiCuCNLi.
OH
SiMe2Ph
18
11% from 1 equiv.2
37% from 1 equiv.2
and inverse addition
O
2
+
O
17
A second test was to examine the pattern of reactivity of the
bissilyl-cuprate 2 and the mixed cuprate 22. With this cuprate,
the intermediate corresponding to 3 would carry a carbon lig-
and on the copper in place of the silyl, and any formation of the
bis-adduct 21 would have to be intermolecular, unless it were
the result of ligand exchange followed by intramolecular deliv-
ery. This reagent might also show different chemoselectivity,
allowing cyclisation where it had not occurred before.
Using normal addition, adding the aldehyde 1f and the allylic
acetates 1g and 1h to the mixed cuprate 22 gave higher yields of
the alcohol 8 and the allylsilanes 10 and 12 (Scheme 8) than we
obtained in the earlier work. In the reactions with the allylic
acetates, we again obtained substantial amounts of unchanged
SiMe2Ph
19
55% from 1 equiv.2
33% from 1 equiv.2
and inverse addition
Scheme 6
gave two recognisable products 18 and 19 (Scheme 6). The alco-
hol 18 was only a minor component under normal conditions,
and not even the only product using inverse addition, although
the yield was raised to 37%. Ring-formation clearly needs all
the help it can get.
There are two routes to the products of double addition 21
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900
891

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OH
silyl, when the mixed cuprate 22 delivers the silyl group rather
than the methyl?
With little prospect of achieving cyclisation, we did try one
other pair of functional groups, setting a silylated terminal
acetylene against a terminal acetylene 23 and against a ketone
group 25 (Scheme 10). We already knew that silylated terminal
SiMe2Ph
SiMe2Ph
10%
PhMe2SiCuMeCN Li2
CHO
7
22
+
SiMe2Ph
SiMe2Ph
2
OH
1f
SiMe2Ph
25%
SiMe2Ph
23
14%
OH
24
8
O
SiMe2Ph
SiMe2Ph
22
22
OAc
i, ii
+ 1g
SiMe3
SiMe3
or iii
25%
10
65%
26 25% + 25 50%
(ii)
25
1g
1h
(iii)
55%
20%
+ 1h
Scheme 10 Reagents: i, BF3ؒOEt2; ii, (PhMe2Si)2CuCNLi2; iii, PhMe2-
SiMe2Ph
SiLi.
OAc
10%
acetylenes react with the silyl-cuprate reagent to place, syn
stereospecifically, the silyl group on the internal carbon and the
copper on the silylated carbon.22 This intermediate cannot form
a ring by attacking the other functional group unless it does so
with inversion of configuration at the copper-bearing carbon.
In the event there was no cyclisation, and we obtained in low
yield only the product 24 of silylcupration of the terminal
acetylene. The ketone 25 showed no reaction with the silyl-
cuprate alone, but it did react at the ketone group in the
presence of boron trifluoride–diethyl ether. In this, it was little
different from the silyllithium reagent, which gave the same
alcohol 26 in comparably low yield.
Except for the epoxide 1c, which we prepared from the alde-
hyde 29, we prepared all the substrates 1 from the ketone 1b,
which is the product of an Eschenmoser fragmentation starting
from isophorone. The routes used are summarised in Scheme
11. The ketone 17, likewise, was the product of an Eschenmoser
fragmentation starting from cyclohexenone.
72%
12
Scheme 8
starting material, and in all three cases there was no trace of
cyclisation. We conclude that the mixed cuprate is simply more
selective overall than the bissilyl-cuprate.
With two of the reactions that had shown some cyclisation,
the epoxide 1e now showed a drop in the amount of bis-adduct
6 from 7% to 1%, and the bis-acetylene 1j showed a drop in the
amount of bis-adduct 16 from 43% to 0% (Scheme 9). The last
OH
O
22
SiMe2Ph
4e
1e
1j
1%
+
6
1%
51%
+
5
Experimental
Light petroleum refers to the fraction bp 30–40 ЊC and ether
refers to diethyl ether. J Values are given in Hz.
22
SiMe2Ph
34%
16 0%
Silyl-cupration reactions
+
4j
Method A (normal addition). Typically, the substrate (1
mmol) in dry THF (2 cm3) was added dropwise over 10 min at
Ϫ78 ЊC to lithium bis[dimethyl(phenyl)silyl]cuprate3 [0.7–1.2
mol dmϪ3 in THF, 2.2 mmol, prepared from copper() cyanide]
and the mixture stirred at Ϫ78 ЊC for 2–4 h. The mixture was
allowed to warm slowly to room temperature, quenched with
basic ammonium chloride solution (5 cm3), filtered through
Celite and extracted with ether (3 × 10 cm3). The organic
extracts were combined, washed with basic ammonium chloride
solution (3 × 10 cm3), dried (MgSO4) and evaporated under
reduced pressure. The residue was purified by column chrom-
atography.
Scheme 9
result is the only one striking enough to suggest that intra-
molecular delivery of the silyl group might have been occurring,
but there is an alternative explanation: if the mixed cuprate 22
is less reactive than the homocuprate 2, as we suspect from its
greater selectivity, then the intermediate analogous to 3 will
have more time in which to cyclise. With the remaining reaction
that showed some cyclisation, the αβ-unsaturated ester 1i giving
the ester 4i, the mixed cuprate 22 gave none of the cyclisation
product 4i and only a little more (8%) of the product 15 of
attack only at the αβ-unsaturated ester group.
We conclude that the mixed cuprate 22 has some perhaps
usefully different chemoselectivity, probably by virtue of its
lower reactivity, and that there is no compelling evidence for
intramolecular delivery of the silyl group to the electrophilic
centre in any of the intermediates 3. The puzzle remains: why
mixed cuprates like 3 should react at the vinyl group both
intermolecularly21 and intramolecularly, as here, and not at the
Method B (inverse addition). Typically, the silyl-cuprate was
added dropwise through a cannula (15 cm) to the substrate
(1 mmol) in dry THF (2 cm
mixture was stirred at Ϫ78 ЊC for 2–4 h and worked up as in
Method A.
3) under argon at Ϫ78 ЊC. The
Method C (mixed methylsilyl cuprate). Typically, dimethyl-
892
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900

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1
vinyl protons in the H-NMR spectrum, probably the endo-
cyclic double bond isomers.
O
i
(Z)-2-[Dimethyl(phenyl)silyl]methylidene-1,4,4-trimethyl-
cyclopentanol 4b. Compound 4b (75%) was prepared from the
ketone 1b (11 mmol) by Method A (experiment first carried out
by Helen Hailes); Rf (Et2O–hexane, 1:9) 0.25; νmax(film)/cmϪ1
1e
75%
OAc
O
ii, iii
3580 and 3480 (OH), 1645 (C᎐C), 1250 (SiMe), 1115 (SiPh) and
᎐
840 (SiMe); δH(250 MHz; CDCl3) 7.60–7.55 (2 H, m, o-SiArH),
7.40–7.33 (3 H, m, p- and m-SiArH), 5.54 (1 H, m, CH᎐C), 2.44
1b
᎐
1g
53%
viii
iv, v, vi, vii
(1 H, dd, J 2.3 and 15.2, CH H C᎐C), 2.14 (1 H, d, J 15.1,
᎐
B
A
CH H C᎐C), 1.72 (1 H, d, J 13.7, CH H COH), 1.60 (1 H, d,
᎐
A
B
A
B
SiMe2Ph
J 12.9, CHAHBCOH), 1.25 (1 H, s, MeCOH), 1.23 (1 H, s, OH),
1.02 (3 H, s, MeAMeBC), 0.99 (3 H, s, MeAMeBC), 0.47 (3 H, s,
MeAMeBSi) and 0.38 (3 H, s, MeAMeBSi); δC(CDCl3) 170.1,
141.2, 133.7, 128.9, 127.9, 119, 79.5, 57.5, 52.7, 34.7, 30.1, 29.9,
29.7, 0.4 and Ϫ0.4 (Found: C, 74.55; H, 9.6. C17H26OSi requires
C, 74.4; H, 9.55%). A nuclear Overhauser enhancement (NOE)
was observed at δ 2.14 by irradiating the signals at δ 5.54 and at
δ 2.44, and at δ 2.44 and δ 5.54 by irradiating at δ 2.14, confirm-
ing the double bond geometry. The acetate of this alcohol was
prepared (15%) by the method of Höfle and Steglich;23 Rf
ix
23 71%
85%
1j
OSiMe3
O
v
SiMe3
SiMe3
27 98%
25 91% from 1b
(EtOAc–hexane, 1:9) 0.53; νmax(film)/cmϪ1 1740 (C᎐O), 1635
᎐
O
xii, viii
(C᎐C), 1250 (SiMe), 1115 (SiPh) and 835 (SiMe); δ (250 MHz;
᎐
H
x, xi
CDCl3) 7.58–7.53 (2 H, m, o-SiArH), 7.32–7.30 (3 H, m, p- and
m-SiArH), 5.60 (1 H, m, CH᎐C), 2.41 (1 H, dd, J 2.2 and 15.2,
᎐
CH H C᎐C), 2.24 (1 H, d, J 15.2, CH H C᎐C), 2.13 (1 H, d,
᎐
᎐
B
A
B
A
1d 38%
OTs
OH
OH
J 14.7, CHAHBCOH), 2.03 (1 H, d, J 14.5, CHAHBCOH), 1.64
(3 H, s, MeCO2), 1.57 (3 H, s, MeCOAc), 1.04 (3 H, s, MeA-
MeBC), 1.02 (3 H, s, MeAMeBC), 0.41 (3 H, s, MeAMeBSi) and
0.36 (3 H, s, MeAMeBSi) (Found: C, 71.95; H, 8.9. C19H28O2Si
requires C, 72.1; H, 8.9%).
CHO
viii, xiii
xi, xii
SiMe3
1f
28 88%
99%
1a 45%
ii, iii
xiv
(Z)-4-[Dimethyl(phenyl)silyl]methylidene-2,2-dimethylcyclo-
pentanol 4c. Compound 4c (83%) was prepared from the
epoxide 1c (0.69 mmol) by Method A; Rf (EtOAc–hexane, 1:9)
CO2Me
OAc
64%
0.11; νmax(film)/cmϪ1 3350 (OH), 1625 (C᎐C), 1251 (SiMe), 1115
᎐
(SiPh) and 829 (SiMe); δH(250 MHz; CDCl3) 7.54–7.49 (2 H, m,
o-SiArH), 7.35–7.31 (3 H, m, p- and m-SiArH), 5.53 (1 H, t,
1i 75%
1h
J 2.2, CH᎐C), 3.76 (1 H, br t, J 6.0, CHOH), 2.59 (1 H, ddd,
O
᎐
J 2.3, 6.7 and 18.0, CHAHBCHOH), 2.39 (1 H, br d, J 16.4,
Me2CCHAHB), 2.19 (1 H, br d, J 15.7, Me2CCHAHB), 2.16
(1 H, dd, J 5.8 and 18.2, CHAHBCOH), 1.89 (1 H, br s, OH),
0.95 (3 H, s, MeAMeBC), 0.94 (3 H, s, MeAMeBC), 0.34 (3 H, s,
MeAMeBSi) and 0.33 (3 H, s, MeAMeBSi).
CHO
i
29
1c 18%
Scheme 11 Reagents: i, CH2Br2, BuLi; ii, CH2᎐᎐CHMgBr; iii, Ac2O,
DMAP; iv, LDA, PhMe2SiCl; v, H3Oϩ; vi, LDA, (EtO)2POCl; vii,
LDA; viii, TBAF; ix, LDA, Me3SiCl; x, MCPBA; xi, NaBH4; xii, TsCl,
(Z)-{2-[Dimethyl(phenyl)silyl]methylidene-4,4-dimethylcyclo-
pentyl}methanol 4da. Compound 4da (64%) was prepared from
the epoxide 1d (0.75 mmol) by Method A; Rf (EtOAc–hexane,
DMAP; xiii, NaIO4; xiv, Ph3P᎐CHCO2Me.
᎐
1:9) 0.20; νmax(film)/cmϪ1 3364 (OH), 1638 (C᎐C), 1248 (SiMe),
᎐
(phenyl)silyllithium (0.7–1.2 mol dmϪ3 in THF, 1.1 mmol) and
methyllithium (1.0–1.6 mol dmϪ3 in THF, 1.1 mmol) were
added in succession to a stirred suspension of copper() cyanide
(1.15 mmol) in dry THF (2–3 cm3) under argon at 0 ЊC, and
stirred for an additional 0.5 h. This reagent was then used as in
Methods A and B above.
1113 (SiPh) and 833 (SiMe); δH(250 MHz; CDCl3) 7.52–7.48
(2 H, m, o-SiArH), 7.37–7.32 (3 H, m, p- and m-SiArH), 5.09
(1 H, s, C᎐CHSi), 3.49 (2 H, d, J 4.7, CH OH), 2.55 (1 H, br s,
᎐
2
CHCH OH), 1.80 (1 H, br d, J 14.0, CH H C᎐C), 1.75 (1 H,
᎐
B
2
A
dd, J 8.3 and 12.8, CHAHBCH), 1.62 (1 H, br d, J 14.0, CHAHB-
C᎐C), 1.48 (1 H, dd, J 6.9 and 12.8, CH H CH), 1.04 (3 H, s,
᎐
A
B
The following compounds were prepared in one or more of
these ways.
MeAMeBC), 0.96 (3 H, s, MeAMeBC), 0.31 (3 H, s, MeAMeBSi)
and 0.30 (3 H, s, MeAMeBSi) (Found: C, 74.6; H, 9.75.
C17H26OSi requires C, 74.4; H, 9.55%).
(E)-1-[Dimethyl(phenyl)silyl]methylidene-3,3-dimethylcyclo-
pentane 4a. Compound 4a (75%) was prepared from the
tosylate 1a (1.1 mmol) by Method A (experiment carried out by
(Z)-5-[Dimethyl(phenyl)silyl]methylidene-3,3-dimethylcyclo-
hexanol 4db. Compound 4db (20%) was also prepared from
epoxide 1d; Rf (EtOAc–hexane, 1:9) 0.20; νmax(film)/cmϪ1 3342
Klaus Breuer); Rf (hexane) 0.62; νmax(film)/cmϪ1 1621 (C᎐C),
᎐
1246 (SiMe), 1111 (SiPh) and 839 (SiMe); δH(250 MHz; CDCl3)
7.56–7.48 (2 H, m, o-SiArH), 7.37–7.32 (3 H, m, p- and
(OH), 1618 (C᎐C), 1248 (SiMe), 1112 (SiPh) and 840 (SiMe);
δH(250 MHz; CDCl3) 7.57–7.51 (2 H, m, o-SiArH), 7.36–7.31
᎐
m-SiArH), 5.49 (1 H, t, J 2.2, SiCH᎐C), 2.25 (2 H, br t, J 7.6,
(3 H, m, p- and m-SiArH), 5.37 (1 H, s, C᎐CHSi), 3.58 (1 H, tt,
᎐
᎐
CH CH C᎐C), 2.18 (2 H, br s, Me CCH C᎐C), 1.47 (2 H, t,
J 4.6 and 10.8, CHOH), 2.63 (1 H, ddt, J 1.7, 4.6 and 12.3,
᎐
᎐
2
2
2
2
J 7.6, CH CH C᎐C), 0.97 (6 H, s, Me C) and 0.33 (6 H, s,
CH(OH)CH H C᎐C), 2.03 (1 H, br d, J 12.8, Me CCH -
᎐
eq ax 2 eq
᎐
2
2
2
Me2Si). This compound rearranges on prolonged contact with
H C᎐C), 1.91 (1 H, br d, J 12.8, Me CCH H C᎐C), 1.76 (1 H,
᎐ ᎐
ax 2 eq ax
silica gel to give a mixture of unidentified compounds with
br t, J 11.8, CH(OH)CH H C᎐C), 1.69 (1 H, ddt, J 2.0, 4.1
᎐
eq ax
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900
893

View Article Online
and 12.5, Me2CCHeqHaxCHOH), 1.20 (1 H, br t, J 12.2, Me2-
CCHeqHaxCHOH), 0.98 (3 H, s, MeAMeBC), 0.85 (3 H, s,
MeAMeBC), 0.37 (3 H, s, MeAMeBSi) and 0.35 (3 H, s,
MeAMeBSi) (Found: Mϩ, 274.1753. C17H26OSi requires M,
274.1752). A minor product was also isolated and tentatively
assigned the structure (E)-1,7-bis[dimethyl(phenyl)silyl]-4,4-
dimethylhept-6-en-2-ol (3%); Rf (EtOAc–hexane, 1:9) 0.30;
νmax(film)/cmϪ1 3405 (OH), 1251 (SiMe), 1115 (SiPh) and 832
(SiMe); δH(250 MHz; CDCl3) 7.53–7.49 (2 H, m, o-SiArH),
7.35–7.32 (3 H, m, p- and m-SiArH), 6.08 (1 H, dt, J 7.0 and
hexane, 1:9) 0.20; νmax(film)/cmϪ1 3580 and 3460 (OH), 1610
(C᎐C), 1245 (SiMe), 1110 (SiPh) and 840 (SiMe); δ (250 MHz;
᎐
H
CDCl3) 7.58–7.48 (2 H, m, o-SiArH), 7.39–7.31 (3 H, m, p- and
m-SiArH), 6.07 (1 H, dt, J 7.0 and 18.5, CH᎐CSi), 5.75 (1 H, d,
᎐
J 18.4, C᎐CHSi), 3.74 (1 H, dd, J 4.8 and 7.1, CHOH), 2.11
᎐
(2 H, d, J 6.9, CH C᎐C), 1.42 (2 H, m, CH COH), 0.92 (3 H, s,
᎐
2
2
MeAMeBC), 0.89 (3 H, s, MeAMeBC) and 0.30 (6 H, s, Me2Si)
(Found: C, 72.85; H, 9.2. C24H36OSi2 requires C, 72.65; H,
9.15%).
18.4, CH᎐CSi), 5.73 (1 H, d, J 18.4, C᎐CHSi), 3.98 (1 H, m,
1-[Dimethyl(phenyl)silyl]-3,3-dimethylhex-5-yn-1-ol 8. Com-
pound 8 (7%) was prepared by Method B, and (25%) Method
C; Rf (EtOAc–hexane, 1:9) 0.15; νmax(film)/cmϪ1 3570 and 3470
᎐
᎐
CHOH), 2.03 (2 H, br d, J 6.9, CH C᎐C), 1.26 (2 H, m, Me -
᎐
2
2
CCH2COH), 1.08 (1 H, dd, J 7.7 and 14.7, CHAHBSi), 0.99
(1 H, dd, J 6.0 and 14.7, CHAHBSi), 0.90 (3 H, s, MeAMeBC),
0.87 (3 H, s, MeAMeBC), 0.321 (6 H, s, Me2SiA) and 0.319 (6 H,
s, Me2SiB).
᎐
᎐
(OH), 3300 (᎐CH), 2110 (C᎐C), 1250 (SiMe), 1110 (SiPh) and
᎐
᎐
835 (SiMe); δH(250 MHz; CDCl3) 7.59–7.52 (2 H, m, o-SiArH),
7.41–7.32 (3 H, m, p- and m-SiArH), 3.72 (1 H, dd, J 4.1 and
᎐
8.1, CHOH), 2.20 (1 H, dd, J 2.6 and 16.7, CH H C᎐C), 2.13
᎐
A
B
᎐
(Z)-5-[Dimethyl(phenyl)silyl]methylidene-1,3,3-trimethyl-
cyclohexanol 4e. Compound 4e (65%) was prepared from the
epoxide 1e (4.7 mmol) by Method A, (44%) from the epoxide 1e
(1.3 mmol) by Method B, and (51%) from the epoxide 1e (3.3
mmol) by Method C, which also gave recovered epoxide (12%);
Rf (EtOAc–hexane, 1:9) 0.22; νmax(film)/cmϪ1 3600 and 3480
(1 H, dd, J 2.7 and 16.7, CH H C᎐C), 1.96 (1 H, t, J 2.7,
᎐
A B
HC᎐C), 1.58 (1 H, dd, J 8.2 and 15.2, CH H COH), 1.52 (1 H,
᎐
᎐
A
B
dd, J 4.0 and 15.2, CHAHBCOH), 0.99 (6 H, s, Me2C), 0.33
(3 H, s, MeAMeBSi) and 0.32 (3 H, s, MeAMeBSi) (Found: C,
73.25; H, 9.1. C16H24OSi requires C, 73.8; H, 9.3%).
(OH), 1630 (C᎐C), 1250 (SiMe), 1115 (SiPh) and 840 (SiMe);
δH(250 MHz; CDCl3) 7.60–7.54 (2 H, m, o-SiArH), 7.41–7.33
(1E,6E)- and (1E,6Z)-1,8-Bis[dimethyl(phenyl)silyl]-4,4,6-
trimethylocta-1,6-diene 9. Compounds (1E,6E)-9 and (1E,6Z)-
9 (64%, 7:1) were prepared from the acetate 1g (2.4 mmol) by
Method A, and (88%, 2:1) from the acetate 1g (1.35 mmol) by
Method A, but using 2 equivalents of the silyl-cuprate; Rf (hex-
᎐
(3 H, m, p- and m-SiArH), 5.48 (1 H, d, J 1.0, CH᎐C), 2.28
᎐
(1 H, dd, J 1.5 and 13.9, C᎐CCH H COH), 2.03 (1 H, masked
᎐
eq ax
br d, C᎐CCH H COH), 2.01 (2 H, br s, Me CCH C᎐C), 1.51
᎐
᎐
2
eq ax
2
(1 H, dd, J 0.8 and 14.1, Me2CCHeqHaxCOH), 1.32 (1 H, d,
J 14.1, Me2CCHeqHaxCOH), 1.06 (3 H, s, MeCOH or MeA-
MeBC), 1.00 (3 H, s, MeCOH or MeAMeBC), 0.92 (3 H, s,
MeCOH or MeAMeBC), 0.87 (1 H, s, OH), 0.41 (3 H, s,
MeAMeBSi) and 0.39 (3 H, s, MeAMeBSi) (Found: C, 74.7; H,
9.65. C18H28OSi requires C, 74.95; H, 9.8%).
ane) 0.24; νmax(film)/cmϪ1 1615 (C᎐C), 1250 (SiMe), 1115 (SiPh)
᎐
and 840 (SiMe); δH(250 MHz; CDCl3) (major isomer, assigned
tentatively as 6E) 7.54–7.50 (2 H, m, o-SiArH), 7.36–7.32 (3 H,
m, p- and m-SiArH), 6.13 (1 H, dt, J 18.4 and 7.0, CH᎐CSi),
᎐
5.72 (1 H, d, J 18.4, C᎐CHSi), 5.13 (1 H, br t, J 8.4, CH᎐CMe),
᎐
᎐
2.02 (2 H, dd, J 0.8 and 7.0, CH C᎐CSi), 1.89 [2 H, s, Me -
᎐
2
2
CCH C(Me)᎐C], 1.67 (2 H, d, J 8.4, CH Si), 1.55 (3 H, s,
᎐
2
2
(E)-1-{5-[Dimethyl(phenyl)silyl]-2,2-dimethylpent-4-enyl}-1-
methyloxirane 5. Compound 5 (12%) was prepared by Method
A. (41%) Method B, and (1%) Method C; Rf (EtOAc–hexane,
MeC᎐C), 0.82 (6 H, s, Me C), 0.32 (6 H, s, Me Si ) and 0.28
᎐
2 2 A
(6 H, s, Me2SiB) (minor isomer, assigned tentatively as 6Z) 7.53–
7.47 (2 H, m, o-SiArH), 7.35–7.29 (3 H, m, p- and m-SiArH),
1:9) 0.37; νmax(film)/cmϪ1 1610 (C᎐C), 1245 (SiMe), 1110 (SiPh)
6.13 (1 H, dt, J 18.4 and 7.0, CH᎐CSi), 5.75 (1 H, d, J 18.5,
᎐
᎐
and 835 (SiMe); δH(250 MHz; CDCl3) 7.53–7.47 (2 H, m,
o-SiArH), 7.37–7.30 (3 H, m, p- and m-SiArH), 6.09 (1 H, dt,
C᎐CHSi), 5.28 (1 H, br t, J 8.3, CH᎐CMe), 2.08 (2 H, d, J 7.0,
᎐ ᎐
CH C᎐CSi), 1.88 [2 H, s, Me CCH C(Me)᎐C], 1.73 (3 H, s,
᎐
᎐
2
2
2
J 18.5 and 7.0, CH᎐CSi), 5.77 (1 H, dt, J 18.4 and 1.1,
MeC᎐C), 1.70 (2 H, d, J 8.3, CH Si), 0.88 (6 H, s, Me C), 0.31
᎐
2 2
᎐
C᎐CHSi), 2.60 (1 H, dd, J 0.4 and 4.9, CH H O), 2.57 (1 H, dd,
(6 H, s, Me2SiA) and 0.24 (6 H, s, Me2SiB) (Found: C, 77.05; H,
9.65. C27H40Si2 requires C, 77.05; H, 9.6%). In the run with one
equivalent of the bissilyl-cuprate, starting acetate 1g (10%) was
obtained, together with a minor product assigned the structure
7-[dimethyl(phenyl)silyl]-3,5,5-trimethylocta-1,7-dien-3-yl
acetate (2%); Rf (EtOAc–hexane, 15:85) 0.55; νmax(film)/cmϪ1
᎐
A
B
J 1.2 and 4.9, CHAHBO), 2.14 (1 H, ddd, J 1.2, 7.0 and 13.4,
CH H C᎐C), 2.12 (1 H, ddd, J 1.2, 7.0 and 13.4, CH H C᎐C),
᎐
᎐
B
A
B
A
1.73 (1 H, dd, J 1.2 and 14.2, CHAHBCO), 1.38 (3 H, s, MeCO),
1.28 (1 H, br d, J 14.1, CHAHBCO), 1.00 (3 H, s, MeAMeBC),
0.97 (3 H, s, MeAMeBC) and 0.32 (6 H, s, Me2Si) (Found: C,
74.95; H, 9.95. C18H28OSi requires C, 74.95; H, 9.8%).
1740 (C᎐O), 1250 (SiMe), 1110 (SiPh), 840 and 820 (SiMe);
᎐
δH(250 MHz; CDCl3) 7.53–7.48 (2 H, m, o-SiArH), 7.34–7.30
(3 H, m, p- and m-SiArH), 5.87 (1 H, dd, J 11.0 and 17.5,
(E)-1,7-Bis[dimethyl(phenyl)silyl]-2,4,4-trimethylhept-6-en-2-
ol 6. Compound 6 (7%) was prepared by Method A, (10%)
Method B, and (1%) Method C; Rf (EtOAc–hexane, 1:9) 0.27;
CH᎐CH ), 5.78 (1 H, d, J 2.9, CH H ᎐CSi), 5.63 (1 H, d, J 2.9,
᎐
᎐
B
2
A
CH H ᎐CSi), 5.05 (1 H, dd, J 0.9 and 17.4, CH H ᎐CH), 4.97
᎐
B
᎐
B
A
A
νmax(film)/cmϪ1 3580 and 3475 (OH), 1610 (C᎐C), 1245 (SiMe),
(1 H, dd, J 0.9 and 11.0, CH H ᎐CH), 2.12 (2 H, m, CH C᎐C),
᎐ ᎐
A B 2
᎐
1110 (SiPh) and 825 (SiMe); δH(250 MHz; CDCl3) 7.56–7.52
(2 H, m, o-SiArH), 7.37–7.33 (3 H, m, p- and m-SiArH), 6.14 (1
1.94 (3 H, s, MeCO2), 1.57 (2 H, br s, CH2COAc), 1.48 (3 H, s,
MeCOAc), 0.88 (3 H, s, MeAMeBC), 0.87 (3 H, s, MeAMeBC),
0.37 (3 H, s, MeAMeBSi) and 0.36 (3 H, s, MeAMeBSi).
H, dt, J 18.5 and 7.0, CH᎐CSi), 5.77 (1 H, d, J 18.5, C᎐CHSi),
᎐
᎐
2.14 (2 H, dd, J 1.0 and 7.0, CH C᎐C), 1.52 (1 H, d, J 14.9,
᎐
2
Me2CCHAHBCO), 1.47 (1 H, d, J 14.9, Me2CCHAHBCO), 1.32
(1 H, d, J 15.0, CHAHBSi), 1.29 (3 H, s, MeCOH), 1.27 (1 H, d,
J 15.3, CHAHBSi), 1.00 (3 H, s, MeAMeBC), 0.99 (3 H, s,
MeAMeBC), 0.38 (6 H, s, Me2SiA) and 0.34 (6 H, s, Me2SiB)
(Found: C, 73.3; H, 9.7. C26H48OSi2 requires C, 73.5; H, 9.5%).
(E)- and (Z)-8-[Dimethyl(phenyl)silyl]-4,4,6-trimethyloct-6-
en-1-yne 10. Compounds (E)-10 and (Z)-10 (51%, 5:1) were
prepared and starting acetate (44%) recorded from the acetate
1g (1.03 mmol) by Method B, and (65%, 6:1) together with the
starting acetate (25%) from the acetate 1g (0.72 mmol) by
Method C; Rf (hexane) 0.25; νmax(film)/cmϪ1 3310 (᎐CH), 2120
᎐
᎐
᎐
(E)-1,6-Bis[dimethyl(phenyl)silyl]-3,3-dimethylhex-5-en-1-ol
7. Compound 7 (45%) was prepared from the aldehyde 1f (2.8
mmol) by Method A, (70%) from the aldehyde 1f (1.48 mmol)
by Method A, but using 2 equivalents of the silyl-cuprate,
(23%) from the aldehyde 1f (1.8 mmol) by Method B, and (10%)
from the aldehyde 1f (1.6 mmol) by Method C; Rf (EtOAc–
(C᎐C), 1250 (SiMe), 1115 (SiPh) and 835 (SiMe); δ (250 MHz;
᎐
H
CDCl3) (major isomer, assigned tentatively as E) 7.56–7.49
(2 H, m, o-SiArH), 7.36–7.30 (3 H, m, p- and m-SiArH), 5.21
᎐
᎐
(1 H, br t, J 8.5, CH᎐C), 1.99 (5 H, m, CH C᎐C, HC᎐C and
᎐
᎐
᎐
2
Me CCH C᎐C), 1.67 (2 H, d, J 8.5, CH Si), 1.56 (3 H, s,
᎐
2
2
2
MeC᎐C), 0.92 (6 H, s, Me C) and 0.30 (6 H, s, Me Si) (some
᎐
2
2
894
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900

View Article Online
peaks for the minor isomer, assigned tentatively as Z) 5.31 (1 H,
gel to give, probably, methyl 2-[dimethyl(phenyl)silyl]methyl-
᎐
br t, J 8.4, CH᎐C), 2.10 (1 H, d, J 2.6, CH C᎐C), 1.67 (2 H, d,
4,4-dimethylcyclopent-1-enylmethanecarboxylate and methyl
2-[dimethyl(phenyl)silyl]methyl-4,4-dimethylcyclopent-2-enyl-
methanecarboxylate. The vinylic signal in the 1H-NMR
spectrum shifts from δ 5.55 to δ 5.00 and is reduced in intensity.
To avoid this rearrangement during the purification, silica gel
impregnated with ammonia was used. Several other runs were
carried out using different silyl-cuprate reagents, stoichio-
metries, and protocols, but this was the highest yield obtained.
᎐
᎐
2
J 8.5, CH Si), 1.75 (3 H, s, MeC᎐C), 0.97 (6 H, s, Me C) and
᎐
2
2
0.26 (6 H, s, Me2Si).
(1E,6E)- and (1E,6Z)-1,8-Bis[dimethyl(phenyl)silyl]-4,4-
dimethylocta-1,6-diene 11. Compounds (1E,6E)-11 and
(1E,6Z)-11 (51%, 2:1 or 1:2) were prepared from the acetate 1h
(1.0 mmol) by Method A together with starting acetate (14%),
(68%, 1.4:1 or 1:1.4) from the acetate 1h (1.05 mmol) by
Method A, but using 2 equivalents of the silyl-cuprate, and
(47%, 1.2:1 or 1:1.2) from the acetate 1h (1.03 mmol) by
Methyl 3-[dimethyl(phenyl)silyl]-5,5-dimethyloct-7-ynoate 15
and tentatively methyl (E)-7-[dimethyl(phenyl)silyl]-5,5-di-
methylocta-2,7-dienoate. These compounds (7%, 3:1) were pre-
pared using the 1:1 silyl–copper reagent by Method B; Rf
Method B; Rf (hexane) 0.30; νmax(film)/cmϪ1 1610 (C᎐C), 1245
᎐
(SiMe), 1115 (SiPh) and 840 (SiMe); δH(250 MHz; CDCl3)
(major isomer) 7.54–7.47 (2 H, m, o-SiArH), 7.35–7.32 (3 H, m,
(EtOAc–hexane, 1:9) 0.36; νmax(film)/cmϪ1 3350 (᎐CH), 2180
᎐
᎐
᎐
p- and m-SiArH), 6.09 (1 H, dt, J 18.4 and 7.1, CH᎐CSi), 5.73
and 2110 (C᎐C), 1725 (C᎐O), 1650 (C᎐C), 1251 (SiMe), 1200
᎐
᎐ ᎐ ᎐
(1 H, d, J 18.5, C᎐CHSi), 5.32 (2 H, m, CH᎐CHCH Si), 1.98
(C–O), 1110 (SiPh) and 820 (SiMe); δH(250 MHz; CDCl3)
(major isomer 15) 7.52–7.46 (2 H, m, o-SiArH), 7.34–7.29 (3 H,
᎐
᎐
2
(2 H, dd, J 1.0 and 7.0, CH C᎐CSi), 1.83 (2 H, m, CH C᎐
᎐
᎐
2
2
CCH2Si), 1.68 (2 H, br d, J 7.2, CH2Si), 0.79 (6 H, s, Me2C),
0.32 (6 H, s, Me2SiA) and 0.26 (3 H, s, Me2SiB) (some peaks for
m, p- and m-SiArH), 3.48 (3 H, s, MeO), 2.41 (2 H, br d, J 6.2,
᎐
CH CO Me), 1.98 (3 H, m, CH C᎐CH), 1.50 (1 H, dd, J 1.7
᎐
2
2
2
the minor isomer) 6.10 (1 H, dt, J 18.4 and 7.0, CH᎐CSi), 5.74
and 14.4, Me2CCHAHBCSi), 1.40 (1 H, m, CHSi), 1.19 (1 H, dd,
J 8.1 and 14.4, Me2CCHAHBCSi), 0.88 (3 H, s, MeAMeBC), 0.86
(3 H, s, MeAMeBC) and 0.27 (6 H, s, Me2Si) (some suggestive
signals for the minor isomer) 7.52–7.46 (2 H, m, o-SiArH),
7.34–7.29 (3 H, m, p- and m-SiArH), 6.93 (1 H, dt, J 15.5 and
᎐
(1 H, d, J 18.5, C᎐CHSi), 2.03 (2 H, dd, J 1.1 and 7.0, CH C᎐
᎐
᎐
2
CSi), 0.84 (6 H, s, Me2C) and 0.36 (6 H, s, Me2Si) (Found: C,
76.7; H, 9.55. C26H38Si2 requires C, 76.75; H, 9.4%).
(E)- and (Z)-8-[Dimethyl(phenyl)silyl]-4,4-dimethyloct-6-en-
1-yne 12. Compounds (E)-12 and (Z)-12 (20%, 2.7:1 or 1:2.7)
were prepared by Method B, (72%, 2:1 or 1:2) together with
starting acetate (10%) by Method C; Rf (hexane) 0.30;
7.8, CH᎐CHCO Me), 5.78 (1 H, d, J 2.7, CH H ᎐CSi), 5.71
᎐ ᎐
2 A B
(1 H, d, J 15.5, CH᎐CHCO Me), 5.64 (1 H, d J 2.8, CH H ᎐
᎐
᎐
B
2
A
CSi), 3.71 (3 H, s, MeO), 2.06 (4 H, m, CH C᎐CCO Me and
᎐
2
2
CH2CSi=C), 0.79 (6 H, s, Me2C) and 0.35 (6 H, s, Me2Si)
(Found: C, 72.1; H, 8.85. C19H28O2Si requires C, 72.1; H,
8.9%).
νmax(film)/cmϪ1 3300 (᎐CH), 2120 (C᎐C), 1245 (SiMe), 1110
᎐
᎐
᎐
᎐
(SiPh) and 835 (SiMe); δH(250 MHz; CDCl3) (major isomer)
7.55–7.49 (2 H, m, o-SiArH), 7.36–7.30 (3 H, m, p- and
m-SiArH), 5.48 (1 H, m, C᎐CHCH Si), 5.30 (1 H, m, CH᎐
Methyl (E)-3,8-bis[dimethyl(phenyl)silyl]-5,5-dimethyloct-7-
enoate 13 and methyl 3,7-bis[dimethyl(phenyl)silyl]-5,5-di-
methyloct-7-enoate 14. Compounds 13 and 14 (65%, 2.2:1)
were prepared from the ester 1i (1.32 mmol) by Method A using
2 equivalents of the silyl-cuprate; Rf (EtOAc–hexane, 1:9) 0.40;
νmax(film)/cmϪ1 1730 (C᎐O), 1615 (C᎐C), 1250 (SiMe), 1110
᎐
᎐
2
᎐
᎐
CHCH Si), 2.03 (2 H, d, J 2.6, CH C᎐C), 1.96 (3 H, m, HC᎐C
᎐
᎐
2
2
and Me CCH C᎐C), 1.71 (2 H, m, CH Si), 0.94 (6 H, s, Me C)
᎐
2
2
2
2
and 0.28 (6 H, s, Me2Si) (one peak for the minor isomer) 0.89
(6 H, s, Me2C) (Found: C, 79.85; H, 9.65. C18H26Si requires C,
79.95; H, 9.7%).
᎐
᎐
(SiPh), 829 and 815 (SiMe); δH(250 MHz; CDCl3) 13 7.54–7.46
(2 H, m, o-SiArH), 7.38–7.30 (3 H, m, p- and m-SiArH), 6.05
7-[Dimethyl(phenyl)silyl]-5,5-dimethylocta-1,7-dien-3-yl acet-
ate. This compound (9%) was prepared by Method A and (5%)
by Method B; Rf (EtOAc–hexane,1:9) 0.40; νmax(film)/cmϪ1
(1 H, dt, J 18.4 and 7.0, CH᎐CSi), 5.73 (1 H, d, J 18.4,
᎐
C᎐CHSi), 3.48 (3 H, s, MeO), 2.36 (2 H, m, CH CO Me), 1.99
᎐
2
2
1740 (C᎐O), 1240 (SiMe), 1105 (SiPh) and 815 (SiMe); δ (250
(2 H, dd, J 1.3 and 7.0, CH C᎐CSi), 1.44 (2 H, m, Me CCH -
᎐
2 2 2
᎐
H
MHz; CDCl3) 7.51–7.47 (2 H, m, o-SiArH), 7.34–7.30 (3 H, m,
CSi), 1.02 (1 H, m, CHSi), 0.81 (3 H, s, MeAMeBC), 0.75 (3 H, s,
MeAMeBC), 0.31 (6 H, s, Me2SiA) and 0.26 (6 H, s, Me2SiB)
p- and m-SiArH), 5.78 (1 H, d, J 2.8, CH H ᎐CSi), 5.66 (1 H,
᎐
B
A
ddd, J 6.2, 10.4 and 17.0, CH᎐CH ), 5.64 (1 H, d, J 2.9, CH -
(some signals for 14) 5.72 (1 H, d, J 2.9, CH H ᎐CSi), 5.59
᎐
A B
᎐
2
A
H ᎐CSi), 5.33 (1 H, m, CHOAc), 5.12 (1 H, dt, J 17.2 and 1.2,
(1 H, d, J 2.9, CH H ᎐CSi), 3.46 (3 H, s, MeO), 0.71 (3 H, s,
᎐
A B
᎐
B
CH H ᎐CH), 5.05 (1 H, dt, J 10.4 and 1.1, CH H ᎐CH), 2.09
MeAMeBC) and 0.66 (3 H, s, MeAMeBC).
᎐
B
᎐
B
A
A
(2 H, s, CH C᎐C), 1.99 (3 H, s, MeCO ), 1.58 (1 H, dd, J 8.6 and
᎐
2
2
14.8, CHAHBCOAc), 1.39 (1 H, dd, J 3.5 and 14.8, CHAHB-
COAc), 0.80 (6 H, s, Me2C) and 0.36 (6 H, s, Me2Si) (Found:
C, 72.95; H, 9.15. C20H30O2Si requires C, 72.65; H, 9.15%).
(E)-1-[Dimethyl(phenyl)silyl]methylidene-4,4-dimethyl-2-
methylidenecyclopentane 4j. Compound 4j (16%) was prepared
from the bisacetylene 1j (0.83 mmol) by Method B, (34%) from
the bisacetylene 1j (0.41 mmol) by Method C; Rf (hexane) 0.40;
νmax(film)/cmϪ1 1248 (SiMe), 1112 (SiPh) and 834 (SiMe);
δH(250 MHz; CDCl3) 7.58–7.49 (2 H, m, o-SiArH), 7.35–7.31
Methyl
(E)-2-[dimethyl(phenyl)silyl]methylidene-4,4-di-
methylcyclopentylmethanecarboxylate 4i. Compound 4i (30%)
together with starting ester (50%) was prepared from the ester
1i (0.62 mmol) using the 1:1 silyl–copper reagent by Method B;
(3 H, m, p- and m-SiArH), 5.59 (1 H, br s, C᎐CHSi), 5.08 (1 H,
᎐
t, J 2.0, CH H ᎐C), 4.84 (1 H, br s, CH H ᎐C), 2.35 (2 H, d,
᎐
B
᎐
B
A
A
Rf (EtOAc–hexane, 1:9) 0.40; νmax(film)/cmϪ1 1730 (C᎐O), 1615
J 1.5, CH C᎐CH ), 2.22 (2 H, s, CH C᎐CHSi), 1.00 (6 H, s,
᎐ ᎐
2 2 2
᎐
(C᎐C), 1245 (SiMe), 1165 (C–O), 1110 (SiPh) and 830 (SiMe);
δH(250 MHz; CDCl3) 7.55–7.51 (2 H, m, o-SiArH), 7.34–7.32
Me2C) and 0.37 (6 H, s, Me2Si). The cyclopentane is sensitive to
acid, giving at least two compounds (1H-NMR) on standing in
deuterated chloroform for 2 d.
᎐
(3 H, m, p- and m-SiArH), 5.55 (1 H, br s, C᎐CHSi), 3.58 (3 H,
᎐
s, MeO), 2.85 (1 H, m, CHCH2CO2Me), 2.41 (1 H, br d,
J 15.5, CH H CO Me), 2.40 (1 H, m, CH H C᎐C), 2.15 (1 H,
dd, J 11.5 and 15.5, CHAHBCO2Me), 2.00 (1 H, br d, J 14.6,
(1E,6E)-1,7-Bis[dimethyl(phenyl)silyl]-4,4-dimethylhepta-1,6-
diene 16. Compound 16 (43%) was prepared by Method B; Rf
᎐
B
A
B
2
A
CH H C᎐C), 1.79 (1 H, ddd, J 1.9, 8.2 and 12.8, CH H CH-
(hexane) 0.28; νmax(film)/cmϪ1 1614 (C᎐C), 1247 (SiMe), 1113
᎐
᎐
A
B
A
B
CO2Me), 1.25 (1 H, m, CHAHBCHCO2Me), 1.10 (3 H, s,
MeAMeBC), 0.87 (3 H, s, MeAMeBC), 0.39 (3 H, s, MeAMeBSi)
and 0.37 (3 H, s, MeAMeBSi) (Found: C, 71.95; H, 8.8; Mϩ (CI),
316.1881. C19H28O2Si requires C, 72.1; H, 8.9%; M, 316.1858).
The ester 4i decomposed on standing in contact with silica
(SiPh) and 837 (SiMe); δH(250 MHz; CDCl3) 7.56–7.48 (2 H, m,
o-SiArH), 7.37–7.31 (3 H, m, p- and m-SiArH), 6.14 (1 H, dt,
J 7.0 and 18.5, CH᎐CSi), 5.78 (1 H, d, J 18.4, C᎐CHSi), 2.07
᎐
᎐
(2 H, dd, J 0.8 and 7.0, CH C᎐C), 0.90 (3 H, s, Me C) and 0.34
᎐
2
2
(3 H, s, Me2Si).
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900
895

View Article Online
(Z)-2-[Dimethyl(phenyl)silyl]methylidene-1-methylcyclo-
pentanol 18. Compound 18 (11%) was prepared from the ketone
1724 (2.6 mmol) by Method A, (28%) from the ketone 17 (1.8
mmol) by Method B; Rf (EtOAc–hexane, 1:9) 0.35; νmax(film)/
s, MeC᎐C), 0.99 (6 H, s, Me C) and 0.91 (3 H, t, J 7.0,
᎐
2
MeCH C᎐C) (Found: C, 87.6; H, 12.05. C H requires C,
᎐
2
12 20
87.75; H, 12.25%). There was no trace of these products from
the reaction of the mixed cuprate on 1g in Method C.
cmϪ1 3572 and 3460 (OH), 1628 (C᎐C), 1246 (SiMe), 1110
᎐
(SiPh) and 828 (SiMe); δH(250 MHz; CDCl3) 7.61–7.54 (2 H, m,
o-SiArH), 7.39–7.30 (3 H, m, p- and m-SiArH), 5.52 (1 H, t,
2-[Dimethyl(phenyl)silyl]-4,4-dimethylocta-1,7-diene
Hydrochloric acid (12 mol dmϪ3 in water, 0.3 cm3), water (0.3
cm3), methanol (0.3 cm3) and the crude allyl- and vinylsilane 11
(0.15 g, 0.37 mmol) in THF (2 cm3) were refluxed for 5 d. Water
(15 cm3) was added and the mixture extracted with ether (3 × 10
cm3). The organic extracts were combined, washed with satur-
ated sodium hydrogen carbonate solution (3 × 10 cm3), dried
(MgSO4) and evaporated under reduced pressure. The residue
was chromatographed (SiO2, hexane) to give the vinylsilane
J 2.1, C᎐CHSi), 2.50 (2 H, m, CH C᎐C), 1.64 (4 H, m, CH -
᎐
᎐
2
2
CH2COH), 1.21 (3 H, s, MeCOH), 0.47 (3 H, s, MeAMeBSi) and
0.38 (3 H, s, MeAMeBSi), and a byproduct, tentatively assigned
as the E-isomer of 18, (9%) by Method B; Rf (EtOAc–hexane,
1:9) 0.37; νmax(film)/cmϪ1 3510 (OH), 1630 (C᎐C), 1245 (SiMe),
᎐
1118 (SiPh) and 840 (SiMe); δH(250 MHz; CDCl3) 7.59–7.49
(2 H, m, o-SiArH), 7.40–7.33 (3 H, m, p- and m-SiArH), 5.18
(1 H, t, J 2.1, C᎐CHSi), 3.61 (1 H, br s, OH), 2.47 (2 H, m,
᎐
(0.016 g, 16%); Rf (hexane) 0.37; νmax(film)/cmϪ1 1640 (C᎐C),
1250 (SiMe), 1110 (SiPh) and 820 (SiMe); δH(250 MHz; CDCl3)
7.54–7.47 (2 H, m, o-SiArH), 7.36–7.31 (3 H, m, p- and m-
᎐
CH C᎐C), 1.79 (4 H, m, CH CH COH), 1.35 (3 H, s, MeCOH)
᎐
2
2
2
and 0.43 (6 H, s, Me2Si).
SiArH), 5.76 (1 H, d, J 2.8, CH H ᎐CSi), 5.75 (1 H, ddt, J 17.1,
᎐
B
A
(E)-7-[Dimethyl(phenyl)silyl]hept-6-en-2-one 19. Compound
19 (55%) was prepared from the ketone 1724 by Method A,
(33%) Method B; Rf (EtOAc–hexane, 1:9) 0.30; νmax(film)/cmϪ1
6.5 and 10.1, CH CH᎐CH ), 5.60 (1 H, d, J 2.9, CH H ᎐CSi),
᎐
᎐
B
2
2
A
4.93 (1 H, ddd, J 1.6, 3.5 and 17.1, CH H ᎐CH), 4.88 (1 H, ddt,
᎐
B
A
J 10.2, 2.2 and 1.2, CH H ᎐CH), 2.07 (2 H, d, J 0.7, Me -
᎐
A
B
2
1716 (C᎐O), 1616 (C᎐C), 1248 (SiMe), 1112 (SiPh), 842 and 824
᎐
᎐
CCH C᎐C), 1.95 (2 H, tq, J 1.3 and 8.1, CH CH᎐CH ),
᎐
᎐
2
2
2
(SiMe); δH(250 MHz; CDCl3) 7.52–7.47 (2 H, m, o-SiArH),
7.37–7.32 (3 H, m, p- and m-SiArH), 6.05 (1 H, dt, J 18.6 and
1.22 (2 H, m, Me2CCH2CH2), 0.77 (6 H, s, Me2C) and 0.37
(6 H, s, Me2Si) (Found: Mϩ, 272.1961. C18H28Si requires M,
272.1960).This relatively involatile product must have come
from the protodesilylation of the regioisomeric vinylsilane
accompanying the substrate.
6.1, CH᎐CSi), 5.77 (1 H, dt, J 18.6 and 1.3, C᎐CHSi), 2.42 (2 H,
᎐
᎐
t, J 7.4, CH CO), 2.11 (5 H, m, MeCO and CH C᎐CSi), 1.69
᎐
2
2
(2 H, quintet, J 7.4, CH2CH2CO) and 0.31 (6 H, s, Me2Si)
(Found: C, 72.95; H, 8.8. C15H22OSi requires C, 73.1; H, 9.0%).
Starting materials
(E)-1,7-Bis[dimethyl(phenyl)silyl]-4,4-dimethylhept-6-en-1-
yne 24. Compound 24 (14%) was prepared from the acetylene
2-(2,2-Dimethylpent-4-ynyl)-2-methyloxirane 1e. Following
Matteson,25 n-butyllithium (1.6 mol dmϪ3 in hexane, 5 cm3) was
added dropwise over 15 min to a well stirred solution of 4,4-
dimethylhept-6-yn-2-one25 (1.0 g, 7.2 mmol) and dibromo-
methane (2.06 g, 11.9 mmol) in dry THF (15 cm3) under argon
at Ϫ78 ЊC, and at room temperature overnight. The mixture
was quenched with saturated ammonium chloride solution (10
cm3) and extracted with ether (3 × 10 cm3). The organic extracts
were combined, dried (MgSO4) and evaporated by careful frac-
tional distillation. The residue was distilled to give the epoxide
(0.82 g, 75%), bp 63–68 ЊC/8 mmHg; Rf (EtOAc–hexane,1:9)
23 (0.41 mmol) by Method B; Rf (hexane) 0.20; νmax(film)/cmϪ1
᎐
2173 (C᎐C), 1613 (C᎐C), 1249 (SiMe), 1114 (SiPh) and 837
᎐
᎐
(SiMe); δH(250 MHz; CDCl3) 7.66–7.61 (2 H, m, o-SiAArH),
7.54–7.49 (2 H, m, o-SiBArH), 7.37–7.33 (6 H, m, p- and
m- SiAArH and p- and m-SiBArH), 6.11 (1 H, dt, J 18.4 and 7.0,
CH᎐CSi), 5.83 (1 H, d, J 18.4, C᎐CHSi), 2.18 (2 H, d, J 7.0,
᎐
᎐
᎐
CH C᎐C), 2.15 (2 H, s, CH C᎐C), 0.99 (6 H, s, Me C), 0.40
᎐
᎐
2
2
2
(6 H, s, Me2SiA) and 0.33 (6 H, s, Me2SiB).
2-[Dimethyl(phenyl)silyl]-4,4-dimethyl-7-trimethylsilylhept-6-
yn-2-ol 26. Compound 26 (25%) was prepared together with the
starting ketone (50%) from the ketone 25 (0.74 mmol) to which
boron trifluoride–ether complex (0.85 mmol) had been added
before addition of the silyl-cuprate by Method A; Rf (EtOAc–
0.32; νmax(film)/cmϪ1 3300 (᎐CH) and 2120 (C᎐C); δ (250 MHz;
CDCl3) 2.66 (1 H, br d, J 4.9, CHAHBO), 2.57 (1 H, dd J 1.3 and
᎐
᎐
᎐
᎐
H
᎐
᎐
2
4.9, CH H O), 2.15 (2 H, d, J 2.6, CH C᎐C), 2.00 (1 H, t, J 2.7,
A
B
᎐
HC᎐C), 1.80 (1 H, dd, J 1.3 and 14.2, CH H CO), 1.44 (1 H, br
᎐
A
B
d, J 14.3, CHAHBCO), 1.39 (3 H, s, MeCO) and 1.07 (6 H, s,
Me2C) (Found: C, 78.75; H, 10.85. C10H16O requires C, 78.9; H,
10.6%). A byproduct was assigned the structure 12,13-epoxy-
4,4,6,10,10,12-hexamethyltrideca-1,7-diyn-6-ol (0.10 g, 5%); Rf
(EtOAc–hexane, 1:9) 0.07; νmax(film)/cmϪ1 3450 (OH), 3300
hexane, 1:9) 0.34; νmax(film)/cmϪ1 3550 and 3490 (OH), 2160
᎐
(C᎐C), 1710 (C᎐O), 1245 (SiMe) and 840 (SiMe); δ (250 MHz;
᎐
᎐
H
CDCl3) 7.59–7.53 (2 H, m, o-SiArH), 7.37–7.33 (3 H, m, p- and
᎐
᎐
B
m-SiArH), 2.35 (1 H, d, J 16.7, CH H C᎐C), 2.21 (1 H, d,
A
᎐
J 16.7, CH H C᎐C), 1.77 (1 H, d, J 15.1, CH H COH), 1.50
᎐
A
B
A
B
᎐
᎐
(᎐CH) and 2120 (C᎐C); δ (250 MHz; CDCl ) 2.64 (1 H, br d,
᎐
᎐
H
3
(1 H, d, J 15.1, CHAHBCOH), 1.36 (3 H, s, MeCOH), 1.07 (3 H,
s, MeAMeBC), 1.04 (3 H, s, MeAMeBC), 0.33 (6 H, s, Me2SiPh)
and 0.13 (6 H, s, Me3Si) (Found: C, 69.15; H, 9.75. C20H34OSi2
requires C, 69.3; H, 9.9%). This compound was also prepared
from the ketone 25 (0.55 mmol) and dimethyl(phenyl)silyl-
lithium (0.65 mmol).
J 4.9, CHAHBO), 2.57 (1 H, dd J 1.9 and 4.2, CHAHBO), 2.33
(2 H, d, J 2.5, CH C᎐CH), 2.16 (2 H, s, CH C᎐CC(Me)OH),
2.00 (1 H, t, J 2.6, HC᎐C), 1.95 (1 H, br s, OH), 1.78 (1 H, dd,
J 1.2 and 14.9, CHAHBCOC), 1.75 (2 H, s, CH2COH), 1.51
(3 H, s, MeCOH), 1.40 (1 H, masked d, CHAHBCOC), 1.38
(3 H, s, MeCOC), 1.17 (3 H, s, MeAMeBCCH2COH), 1.15 (3 H,
s, MeAMeBCCH2COH), 1.05 (3 H, s, MeAMeBCCH2COC) and
1.04 (3 H, s, MeAMeBCCH2COC) (Found: C, 78.4; H, 10.35.
C19H30O2 requires C, 78.55; H, 10.4%).
᎐
᎐
᎐
᎐
2
2
᎐
᎐
(E)- and (Z)-4,4,6-Trimethylnon-6-en-1-yne
Allylic acetate 1g (1.6 mmol) was treated with lithium dimethyl-
cuprate made from methyllithium (4 mmol) and copper()
iodide (2 mmol) in the same way as Method A. Short column
chromatography (SiO2, pentane) gave a mixture of the alkenes
(85%, 3:1 or 1:3); Rf (EtOAc–hexane, 15:85) 0.74; νmax(film)/
3,5,5-Trimethyloct-1-en-7-yn-3-ol. Following Johnson,26 the
ketone 1b (1.80 g, 13.0 mmol) in dry THF (12 cm3) was added
dropwise to a stirred solution of vinylmagnesium bromide (1.0
mol dmϪ3 in THF; 18 cm3) in dry THF (25 cm3) under argon at
0 ЊC. The red–brown solution became clear yellow, the cooling
bath was removed, the solution stirred at room temperature for
2 h, then cooled to 0 ЊC, quenched with saturated ammonium
chloride solution (50 cm3) and extracted with ether (3 × 50
cm3). The organic extracts were combined, washed with water
cmϪ1 3310 (᎐CH) and 2130 (C᎐C); δ (250 MHz; CDCl )
᎐
᎐
᎐
᎐
H
3
᎐
(major) 5.15 (1 H, t, J 7.0 CH᎐C), 2.05 (2 H, d, J 2.8, CH C᎐C),
1.99 (5 H, m, Me CCH C᎐C, MeCH C᎐C and HC᎐C), 1.65
᎐
᎐
2
᎐
᎐
᎐
2
᎐
2
2
(3 H, s, MeC᎐C), 0.95 (6 H, s, Me C) and 0.94 (3 H, t, J 7.1,
᎐
2
MeCH C᎐C) (identifiable peaks for the minor) 5.25 (1 H, t,
᎐
2
᎐
J 7.1 CH᎐C), 2.09 (2 H, d, J 2.6, CH C᎐C), 1.75 (3 H,
᎐
᎐
2
896
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900

View Article Online
until neutral (4 × 80 cm3), dried (MgSO4) and evaporated
under reduced pressure. The alcohol (2.07 g, 96%) was used in the
next reaction without further purification; Rf (EtOAc–hexane,
warm to room temperature overnight, cooled to 0 ЊC, quenched
with water (25 cm3) and extracted with ether (3 × 25 cm3). The
organic extracts were combined, washed with cold hydrochloric
acid (1 mol dmϪ3 in water, 30 cm3), water (3 × 25 cm3) and
saturated sodium hydrogen carbonate solution until neutral
(3 × 30 cm3), dried (MgSO4) and evaporated under reduced
pressure. The residue was chromatographed (SiO2, EtOAc–
hexane, 1:99) to give the acetylene (1.79 g, 73%); Rf (hexane)
15: 85) 0.34; νmax(film)/cmϪ1 3460 (OH), 3300 (᎐CH) and 2120
᎐
᎐
᎐
(C᎐C); δ (250 MHz; CDCl ) 6.00 (1 H, dd, J 10.7 and 17.3,
᎐
H
3
CH᎐CH ), 5.22 (1 H, dd, J 1.2 and 17.3, CH H ᎐C), 5.00 (1 H,
᎐
᎐
B
2
A
᎐
dd, J 1.2 and 10.7, CH H ᎐C), 2.21 (2 H, d, J 2.6, CH C᎐C),
2.01 (1 H, t, J 2.7, HC᎐C), 1.70 (2 H, s, CH COH), 1.63 (1 H, s,
᎐
B
᎐
A
2
᎐
᎐
2
0.24; νmax(film)/cmϪ1 3308 (᎐CH), 2174 and 2117 (C᎐C), 1249
᎐
᎐
OH), 1.27 (3 H, s, MeCOH) and 1.04 (6 H, s, Me2C) (Found: C,
᎐
᎐
79.55; H, 10.85. C11H18O requires C, 79.45; H, 10.9%).
(SiMe), 1115 (SiPh) and 817 (SiMe); δH(250 MHz; CDCl3)
7.66–7.60 (2 H, m, o-SiArH), 7.39–7.34 (3 H, m, p- and
᎐
3,5,5-Trimethyloct-1-en-7-yn-3-yl acetate 1g. Following Höfle
and Steglich,23 acetic anhydride (0.80 g, 0.74 cm3, 7.8 mmol)
was added dropwise to a stirred solution of the alcohol (1.00 g,
6.0 mmol) and 4-dimethylaminopyridine (0.88 g, 7.2 mmol) in
dry dichloromethane (5 cm3) under argon at 0 ЊC. The solution
was kept for 24 h at room temperature, more acetic anhydride
(0.80 g, 7.8 mmol, 0.74 cm3) was added and stirring continued
for 40 h. Water (5 cm3) was added, dichloromethane evaporated
under reduced pressure and the residue extracted with ether
(4 × 20 cm3). The organic extracts were combined, washed with
hydrochloric acid (1.5 mol dmϪ3 in water, 4 × 10 cm3) and sat-
urated sodium hydrogen carbonate solution (3 × 15 cm3), dried
(MgSO4) and evaporated under reduced pressure. The residue
was chromatographed (SiO2, EtOAc–hexane, 4:96) to give the
acetate (0.69 g, 55%); Rf (EtOAc–hexane, 15:85) 0.49;
m-SiArH), 2.29 (2 H, s, CH C᎐CSi), 2.21 (2 H, d, J 2.65,
᎐
2
᎐
᎐
CH C᎐CH), 2.01 (1 H, t, J 2.65, CH C᎐CH), 1.08 (6 H, s,
᎐
᎐
2
2
Me2C) and 0.39 (6 H, s, Me2Si) (Found: Mϩ, 254.1500. C17H22Si
requires M, 254.1491) (Found: C, 80.25; H, 8.9. C17H22Si
requires C, 80.25; H, 8.7%). We assigned the structure 7-
[dimethyl(phenyl)silyl]-4,4-dimethylnona-5,6-dien-1-yne to
a
byproduct (6–7%) in some runs of this reaction; Rf (hexane)
0.30; νmax(film)/cmϪ1 3311 (᎐CH), 2118 (C᎐C), 1932 (C᎐C=C),
᎐
᎐
᎐
᎐
᎐
1253 (SiMe), 1119 (SiPh) and 832 (SiMe); δH(250 MHz; CDCl3)
7.57–7.48 (2 H, m, o-SiArH), 7.40–7.30 (3 H, m, p- and m-
SiArH), 4.99 (1 H, t, J 3.3, CH᎐C᎐C), 2.11 (2 H, d, J 2.6,
᎐ ᎐
᎐
᎐
CH C᎐CH), 1.95 (1 H, t, J 2.6, HC᎐C), 1.89 (2 H, dq, J 3.3 and
᎐
᎐
2
7.3, CH2CH3), 1.08 (3 H, s, MeAMeBC), 1.07 (3 H, s, MeA-
MeBC), 0.98 (3 H, t, J 7.3, CH2CH3), 0.36 (3 H, s, MeAMeBSi)
and 0.32 (3 H, s, MeAMeBSi) (Found: Mϩ, 282.1783. C19H26Si
requires M, 282.1804).
νmax(film)/cmϪ1 3310 (᎐CH), 2115 (C᎐C), 1740 (C᎐O) and 1645
᎐
᎐
᎐
᎐
᎐
(C᎐C); δ (250 MHz; CDCl ) 5.99 (1 H, dd, J 11.0 and 17.4,
᎐
H
3
CH᎐CH ), 5.18 (1 H, dd, J 0.8 and 17.4, CH H ᎐C), 5.05 (1 H,
4,4-Dimethylhepta-1,6-diyne 1j. Following Marshall,31 tetra-
n-butylammonium fluoride (1.0 mol dmϪ3 in THF, 4.3 cm3) was
added dropwise with stirring to the silylacetylene (1.05 g, 4.1
mmol) in dry THF (4 cm3) under argon at 0 ЊC. After 0.5 h,
water (20 cm3) was added and the mixture extracted with ether
(3 × 10 cm3). The organic extracts were combined, washed with
water (3 × 20 cm3), dried (MgSO4) and evaporated under
reduced pressure without heating. The residue was distilled
(Kugelrohr, 65–70 ЊC/20 mmHg) to give the acetylene (0.42 g,
᎐
᎐
B
2
A
dd, J 0.7 and 11.0, CH H ᎐C), 2.21 (1 H, dd, J 2.6 and 16.6,
᎐
B
A
᎐
CH H C᎐C), 2.18 (1 H, d, J 15.2, CH H COAc), 2.13 (1 H,
᎐
A
B
A
B
᎐
dd, J 2.5 and 16.6, CH H C᎐C), 2.01 (3 H, s, MeCO ), 1.99
᎐
A
B
2
᎐
(1 H, t, J 2.6, HC᎐C), 1.76 (1 H, d, J 15.1, CH H COAc), 1.59
᎐
A
B
(3 H, s, MeCOAc) and 1.04 (6 H, s, Me2C) (Found: C, 74.95;
H, 9.8. C13H20O2 requires C, 74.95; H, 9.7%).
7-[Dimethyl(phenyl)silyl]-4,4-dimethylhept-6-yn-2-one. Fol-
lowing Marshall27 and Corey,28 chlorodimethyl(phenyl)silane29
(5.97 g, 5.3 cm3, 35.0 mmol) was added dropwise with stir-
ring to diisopropylamine (3.34 g, 33.0 mmol, 4.6 cm3) and
n-butyllithium (1.5 mol dmϪ3 in hexane, 21.3 cm3) in dry THF
(50 cm3) under argon at Ϫ78 ЊC. After 10 min, the ketone 1b
(2.0 g, 14.5 mmol) in dry THF (10 cm3) was added at Ϫ78 ЊC,
stirred for 1 h at Ϫ78 ЊC, allowed to warm to room temperature
and quenched by stirring overnight with dilute sulfuric acid (1.8
mol dm3 in water, 50 cm3). The mixture was extracted with ether
(3 × 40 cm3), the organic extracts were combined, washed with
water (3 × 30 cm3) and saturated sodium hydrogen carbonate
solution until neutral (3 × 40 cm3), dried (MgSO4) and evapor-
ated under reduced pressure. The residue was chromatographed
(SiO2, EtOAc–hexane, 7:93) to give the ketone (3.83 g, 97%);
85%); Rf (EtOAc–hexane, 1:9) 0.12; νmax(film)/cmϪ1 3303 (᎐CH)
᎐
᎐
᎐
and 2117 (C᎐C); δ (250 MHz; CDCl ) 2.19 (2 H, d, J 2.65,
CH C᎐C), 2.00 (1 H, t, J 2.65, HC᎐C), 1.06 (3 H, s, Me C)
᎐
H
3
᎐
᎐
᎐
᎐
2
2
(Found: Mϩ, 120.0929. C9H12 requires M, 120.0939).
4,4-Dimethyl-2-trimethylsilyl-7-trimethylsilyloxyhept-6-en-1-
yne 27. Following Marshall27 and Corey,28 chlorotrimethyl-
silane (5.98 g, 7.0 cm3, 55 mmol) and the ketone 1b (3.04 g, 22.0
mmol) in dry THF (10 cm3) were added sequentially dropwise
with stirring to diisopropylamine (5.26 g, 52 mmol, 7.29 cm3)
and n-butyllithium (1.52 mol dmϪ3 in hexane, 33 cm3) in dry
THF (75 cm3) under argon at Ϫ78 ЊC, the mixture was stirred at
that temperature for 2 h, quenched with water (20 cm3) and
extracted with ether (3 × 30 cm3). The organic extracts were
combined, washed with cold hydrochloric acid (1 mol dmϪ3, 30
cm3), saturated sodium hydrogen carbonate solution (3 × 30
cm3) and water (3 × 25 cm3), dried (MgSO4) and evaporated
under reduced pressure to give the silyl enol ether (6.08 g, 98%);
Rf (EtOAc–hexane,1:9) 0.35; νmax(film)/cmϪ1 2172 (C᎐C), 1716
᎐
᎐
(C᎐O), 1249 (SiMe), 1115 (SiPh) and 817 (SiMe); δ (250 MHz;
᎐
H
CDCl3) 7.62–7.57 (2 H, m, o-SiArH), 7.35–7.31 (3 H, m, p- and
᎐
m-SiArH), 2.44 (2 H, s, CH CO), 2.30 (2 H, s, CH C᎐C), 1.06
᎐
2
2
(6 H, s, Me2C) and 0.36 (6 H, s, Me2Si) (Found: Mϩ, 272.1608.
Rf (EtOAc–hexane, 1:9) 0.65; νmax(film)/cmϪ1 2180 (C᎐C), 1620
᎐
᎐
C17H24OSi requires M, 272.1596).
(C᎐C), 1250 (SiMe), 1030 (C–O) and 840 (SiMe); δ (250 MHz;
᎐
H
CDCl ) 4.07 (1 H, s, CH H ᎐C), 4.03 (1 H, s, CH H ᎐C), 2.17
᎐
᎐
B
3
A
B
A
᎐
1-[Dimethyl(phenyl)silyl]-4,4-dimethylhepta-1,6-diyne
23.
(2 H, s, CH C᎐C), 2.01 (2 H, s, CH C᎐C), 0.99 (6 H, s, Me C),
᎐ ᎐
2 2 2
Following Negishi,30 diisopropylamine (1.02 g, 1.42 cm3, 10.1
mmol) and n-butyllithium (1.35 mol dmϪ3 in hexane, 7.5 cm3) in
dry THF (15 cm3) under argon at 0 ЊC was stirred for 30 min,
then cooled to Ϫ78 ЊC and the ketone (2.6 g, 9.6 mmol) in dry
THF (10 cm3) was added. After 15 min diethyl chlorophosphate
(1.74 g, 1.5 cm3, 10.1 mmol) was added dropwise, and the solu-
tion stirred at room temperature for 2.5 h, then cooled again to
Ϫ78 ЊC and transferred by cannula over 0.5 h to a stirred solu-
tion of diisopropylamine ( 2.23 g, 22.0 mmol, 3.1 cm3) and
n-butyllithium (1.35 mol dmϪ3 in hexane, 15.4 cm3) in dry THF
(25 cm3) under argon at Ϫ78 ЊC. The mixture was allowed to
0.20 (9 H, s, Me3SiO) and 0.14 (9 H, s, Me3Si) (Found: C, 63.65;
H, 10.6. C15H30OSi2 requires C, 63.75; H, 10.7%).
4,4-Dimethyl-7-trimethylsilylhept-6-yn-2-one 25. This was
prepared in the same way as the enol ether 27 above, but the
reaction was quenched with sulfuric acid (1 mol dmϪ3 in water,
100 cm3) and stirred overnight. Workup and chromatography
(SiO2, EtOAc–hexane, 7:93) gave the ketone (4.2 g, 91%); Rf
(EtOAc–hexane,1:9) 0.34; νmax(film)/cmϪ1 2180 (C᎐C), 1720
᎐
᎐
(C᎐O), 1250 (SiMe) and 845 (SiMe); δ (250 MHz; CDCl )
᎐
H
3
᎐
2.45 (2 H, s, CH C᎐O), 2.25 (2 H, s, CH C᎐C), 2.13 (3 H, s,
᎐
᎐
2
2
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900
897

View Article Online
MeC᎐O), 1.06 (6 H, s, Me C) and 0.14 (9 H, s, Me Si) (Found:
C, 68.3; H, 10.6. C12H22OSi requires C, 68.5; H, 10.55%).
THF, 8 cm3) was added dropwise with stirring to the tosylate
(1.22 g, 3.18 mmol) in THF (15 cm3) under argon at room
temperature. The dark green solution was stirred for 10 min,
water (10 cm3) added and the mixture extracted with ether
(4 × 15 cm3). The organic extracts were combined, washed with
water (4 × 15 cm3), dried (MgSO4) and evaporated under
reduced pressure without heating. The residue was chromato-
graphed (SiO2, Et2O–light petroleum, 6:94) to give the epoxide
(0.21 g, 48%) in low yield because of its volatility; Rf (EtOAc–
᎐
2
3
1-Hydroxy-4,4-dimethyl-7-trimethylsilylhept-6-yn-2-one. Fol-
lowing Rubottom,32 m-chloroperbenzoic acid (80% purity, 3.65
g, 17 mmol) was added in 10 portions over 15 min with stirring
to the enol ether 27 (3.82 g, 13.6 mmol) in dry dichloromethane
(20 cm3) under argon at 0 ЊC. The white suspension was stirred
at room temperature for 10 min, hydrochloric acid (1.5 mol
dmϪ3 in water, 20 cm3) was added, and the mixture stirred at
room temperature overnight. The mixture was extracted with
dichloromethane (3 × 35 cm3), the organic extracts were com-
bined, washed with saturated sodium hydrogen carbonate
solution (4 × 25 cm3) and water (2 × 25 cm3), dried (MgSO4)
and evaporated under reduced pressure to give the hydroxy-
ketone (3.02 g, 98%), which was used in the next step. A sample
was chromatographed (SiO2, EtOAc–hexane, 15:85) to give a
purer sample of the hydroxyketone; Rf (EtOAc–hexane, 2:8)
hexane, 2:8) 0.51; νmax(film)/cmϪ1 3320 (᎐CH) and 2130 (C᎐C);
᎐
᎐
᎐
᎐
δH(250 MHz; CDCl3) 2.97 (1 H, m, CH2CHO), 2.75 (1 H, br t,
J 4.5, CHAHBO), 2.45 (1 H, dd, J 2.7 and 5.1, CHAHBO), 2.20
᎐
(1 H, dd, J 2.6 and 16.7, CH H C᎐C), 2.14 (1 H, dd, J 2.7 and
᎐
A
B
᎐
᎐
B
᎐
16.7, CH H C᎐C), 2.00 (1 H, t, J 2.6, HC᎐C), 1.58 (1 H, dd,
᎐
A
J 5.1 and 14.2, CHAHBCHO), 1.49 (1 H, dd, J 6.7 and 14.2,
CHAHBCHO) and 1.08 (6 H, s, Me2C) (Found: C, 78.1; H, 10.1.
C9H14O requires C, 78.2; H, 10.2%).
0.28; νmax(film)/cmϪ1 3470 (OH), 2180 (C᎐C), 1720 (C᎐O), 1250
᎐
3,3-Dimethylhex-5-ynal 1f. Following Marshall31 and
Roush,34 tetra-n-butylammonium fluoride (1.0 mol dmϪ3 in
THF, 14 cm3) was added dropwise with stirring to the diol
28 (2.85 g, 12.5 mmol) in THF (12 cm3) at room temperature,
and the mixture stirred for 30 min at room temperature. This
solution was used directly in the next step, but a sample of
4,4-dimethylhept-6-yne-1,2-diol was characterised; Rf (EtOAc–
᎐
᎐
(SiMe) and 840 (SiMe); δH(250 MHz; CDCl3) 4.20 (2 H, s,
CH OH), 3.15 (1 H, br s, OH), 2.41 (2 H, s, Me CCH C᎐O),
᎐
2
2
2
᎐
2.24 (2 H, s, CH C᎐C), 1.08 (6 H, s, Me C) and 0.14 (9 H,
᎐
2
2
s, Me3Si) (Found: Mϩ, 226.1383. C12H22O2Si requires M,
226.1389).
4,4-Dimethyl-7-trimethylsilylhept-6-yne-1,2-diol 28. Sodium
borohydride (0.27 g, 7.1 mmol) was added in 10 portions over
15 min with stirring to the hydroxyketone (3.29 g, 14.6 mmol) in
methanol (40 cm3) at 0 ЊC and the mixture stirred for 20 min at
0 ЊC. The solvent was removed under reduced pressure, water
(40 cm3) added and the mixture extracted with ether (5 × 20
cm3). The organic extracts were combined, washed with water
(40 cm3) and brine (2 × 20 cm3), dried (MgSO4) and evaporated
under reduced pressure to give crude diol (3.01 g, 90%) contain-
ing a small amount of the corresponding desilylated diol. A
sample was chromatographed (SiO2, EtOAc–hexane, 1:1) to
hexane, 1:1) 0.19; νmax(film)/cmϪ1 3370 (OH), 3300 (᎐CH) and
᎐
᎐
᎐
2120 (C᎐C); δ (250 MHz; CDCl ) 3.84 (1 H, tt, J 3.0 and 8.2,
᎐
H
3
CH2CHOH), 3.56 (1 H, dd, J 3.3 and 10.9, CHAHBOH), 3.38
(1 H, dd, J 8.2 and 10.9, CHAHBOH), 2.37 (2 H, br s, 2 × OH),
᎐
2.21 (1 H, dd, J 2.7 and 16.7, CH H C᎐C), 2.15 (1 H, dd, J 2.7
᎐
A
B
᎐
and 16.7, CH H OH), 2.01 (1 H, t, J 2.7, HC᎐C), 1.47 (1 H, dd,
᎐
A
B
J 8.3 and 14.7, Me2CCHAHBCHOH), 1.36 (1 H, dd, J 2.6 and
14.7, Me2CCHAHBCHOH), 1.04 (3 H, s, MeAMeBC) and 1.03
(3 H, s, MeAMeBC). The solution was diluted with THF (15
cm3) and water (40 cm3), and then stirred under argon at room
temperature with sodium periodate (3.21 g, 15.0 mmol), added
in 10 portions over 15 min. After 1.5 h stirring at room temper-
ature, water (60 cm3) was added and the mixture extracted with
ether (3 × 50 cm3). The organic extracts were combined, washed
with saturated sodium hydrogen carbonate solution (5 × 50
cm3), dried (MgSO4) and evaporated under reduced pressure
without heating to give the aldehyde35 (1.53 g, 99%). A sample
was chromatographed (SiO2, Et2O–pentane, 8:92); Rf (EtOAc–
give the diol; Rf (EtOAc–hexane, 1:1) 0.31; νmax(film)/cmϪ1 3360
᎐
(OH), 2180 (C᎐C), 1250 (SiMe) and 840 (SiMe); δ (250 MHz;
᎐
H
CDCl3) 3.85 (1 H, tt, J 3.2 and 8.0, CHOH), 3.54 (1 H, dd, J 3.4
and 10.9, CHAHBOH), 3.39 (1 H, dd, J 8.1 and 10.9, CHAHB-
᎐
OH), 2.24 (2 H, s, 2 × OH), 2.20 (2 H, s, CH C᎐C), 1.45 (1 H,
᎐
2
dd, J 7.9 and 14.8, Me2CCHAHBCHOH), 1.37 (1 H, dd, J 2.9
and 14.8, Me2CCHAHBCHOH), 1.03 (3 H, s, MeAMeBC), 1.02
(3 H, s, MeAMeBC) and 0.14 (9 H, s, Me3Si) (Found: C, 62.8; H,
10.6. C12H24O2Si requires C, 63.1; H, 10.6%).
hexane, 1:9) 0.30; νmax(film)/cmϪ1 3280 (᎐CH), 2740 (CH alde-
᎐
᎐
᎐
hyde), 2115 (C᎐C) and 1715 (C᎐O); δ (250 MHz; CDCl ) 9.80
᎐
᎐
H
3
(1 H, t, J 2.7, HC᎐O), 2.42 (2 H, d, J 2.7, CH CHO), 2.22 (2 H,
᎐
2
2-Hydroxy-4,4-dimethyl-7-trimethylsilylhept-6-yn-1-yl
᎐
᎐
d, J 2.6, CH C᎐C), 2.04 (1 H, t, J 2.6, HC᎐C) and 1.13 (6 H, s,
᎐
᎐
2
toluene-p-sulfonate. Toluene-p-sulfonyl chloride (0.21 g, 1.11
mmol) was added in 4 portions over 5 min with stirring to the
diol 28 (0.21 g, 0.92 mmol) and 4-dimethylaminopyridine
(0.011 g, 0.09 mmol) in dry pyridine (1 cm3) under argon at
room temperature, and stirred overnight. Water (4 cm3) was
added and the mixture extracted with ether (3 × 10 cm3). The
organic extracts were combined, washed with hydrochloric acid
(1.5 mol dmϪ3 in water, 4 × 5 cm3) and saturated sodium hydro-
gen carbonate solution (4 × 5 cm3) and water (2 × 5 cm3), dried
(MgSO4) and evaporated under reduced pressure. The residue
was chromatographed (SiO2, EtOAc–hexane, 1:9 and then
15:85) to give the tosylate (0.28 g, 79.5%); Rf (EtOAc–hexane,
Me2C).
3,3-Dimethylhex-5-yn-1-ol. Sodium borohydride (0.23 g, 6.1
mmol) was added in 10 portions over 15 min with stirring to the
aldehyde 1f (1.23 g, 9.9 mmol) in methanol (40 cm3) at 0 ЊC. The
solvent was removed under reduced pressure, water (50 cm3)
added and the mixture extracted with ether (4 × 50 cm3). The
organic extracts were combined, washed with water (2 × 50 cm3)
and brine (50 cm3), dried (MgSO4) and evaporated under
reduced pressure. The residue was chromatographed (SiO2,
EtOAc–hexane, 1:1) to give the alcohol (0.72 g, 58%); Rf
(EtOAc–hexane, 1:1) 0.38; νmax(film)/cmϪ1 3400 (OH), 3308
2:8) 0.25; νmax(film)/cmϪ1 3540 (OH), 2180 (C᎐C), 1600 (ArH),
᎐
᎐
᎐
᎐
(᎐CH) and 2115 (C᎐C); δ (250 MHz; CDCl ) 3.72 (2 H, t, J 7.3,
᎐
᎐
H
3
1450 (SiMe), 1190 and 1180 (S᎐O) and 840 (SiMe); δ (250
᎐
H
᎐
᎐
2
CH OH), 2.11 (2 H, d, J 2,7, CH C᎐C), 2.00 (1 H, t, J 2.6,
HC᎐C), 1.63 (2 H, t, J 7.3, CH CH OH), 1.24 (1 H, br s, OH)
2
MHz; CDCl3) 7.79 (2 H, d, J 8.3, o-SArH), 7.34 (2 H, d, J 8.0,
m-SArH), 3.95 (2 H, m, CHOH and CHAHBOSO2), 3.84 (1 H,
᎐
᎐
2
2
and 1.00 (6 H, s, Me2C).
dd, J 7.8 and 18.3, CHAHBOSO2), 2.44 (3 H, s, MePh), 2.16
᎐
(2 H, s, CH C᎐C), 1.44 (1 H, dd, J 8.2 and 14.7, Me CCH -
᎐
2
2
A
3,3-Dimethylhex-5-yn-1-yl toluene-p-sulfonate 1a. Toluene-p-
sulfonyl chloride (1.14 g, 6.0 mmol) was added in 10 portions
over 15 min with stirring to 3,3-dimethylhex-5-yn-1-ol (0.51 g,
4.0 mmol) and 4-dimethylaminopyridine (0.048 g, 0.4 mmol) in
dry pyridine (5 cm3) under argon at room temperature. After
15 min the mixture was quenched with water (15 cm3) and
HBCHOH), 1.35 (1 H, dd, J 2.8 and 14.7, Me2CCHAHB-
CHOH), 0.99 (3 H, s, MeAMeBC), 0.98 (3 H, s, MeAMeBC) and
0.12 (9 H, s, Me3Si).
2-(2,2-Dimethylpent-4-ynyl)oxirane 1d. Following Tera-
shima,33 tetra-n-butylammonium fluoride (1.0 mol dmϪ3 in
898
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900

View Article Online
extracted with ether (4 × 20 cm3). The organic extracts were
combined, washed with hydrochloric acid (1.5 mol dmϪ3 in
water, 4 × 25 cm3), saturated sodium hydrogen carbonate solu-
tion (4 × 25 cm3), water (25 cm3) and brine (25 cm3), dried
(MgSO4) and evaporated under reduced pressure to give the
tosylate (0.86 g, 77%); Rf (EtOAc–hexane, 1:1) 0.58; νmax(film)/
(1 H, t, J 2.7, HC᎐C), 0.94 (3 H, s, Me Me C) and 0.93 (3 H, s,
MeAMeBC).
᎐
᎐
A
B
Acknowledgements
We thank the British Council and the Ministerio de Educación
y Ciencia for a Fleming award to E. M. de M. We thank Helen
Hailes for first carrying out the reaction on the ketone 1b as an
undergraduate project, and we thank Klaus Breuer of the
RWTH Aachen for carrying out uniquely the reaction on the
tosylate 1a, and for repeating many of the other reactions.
I (I. F.) also acknowledge the warm encouragement and
support given to me over the years by Ralph Raphael, whom
I greatly miss. It has been a satisfying coincidence that I have
been able to pay, in this special issue of the Journal, what small
tribute I can with a paper about acetylenes, a functional group
for which we shared an enthusiasm, dating back to the very
beginning of my career.
cmϪ1 3290 (᎐CH), 2115 (C᎐C), 1597 (aromatic C᎐C) and 1176
᎐
᎐
᎐
᎐
᎐
(S᎐O); δ (250 MHz; CDCl ) 7.78 (2 H, d, J 8.3, o-SArH), 7.34
᎐
H
3
(2 H, d, J 8.3, m-SArH), 4.10 (2 H, t, J 7.2, CH2O), 2.44 (3 H,
᎐
s, MePh), 2.03 (2 H, d, J 2.6, CH C᎐C), 1.95 (1 H, dt, J 2.6,
᎐
2
᎐
HC᎐C), 1.70 (2 H, t, J 7.2, CH CH O) and 0.96 (6 H, s, Me C).
᎐
2
2
2
5,5-Dimethyloct-1-en-7-yn-3-ol. This was prepared from
the aldehyde 1f (0.63 g, 5.1 mmol), vinylmagnesium bromide
(1.0 mol dmϪ3 in THF, 7 cm3) and THF (15 cm3) as for 3,3-
dimethylhex-5-yn-1-ol, to give the alcohol (0.73 g, 94%); Rf
(EtOAc–hexane, 1:1) 0.62; νmax(film)/cmϪ1 3380 (OH), 3310
᎐
᎐
(᎐CH) and 2125 (C᎐C) and 1640 (C᎐C); δ (250 MHz; CDCl )
᎐
᎐
᎐
H
3
5.89 (1 H, ddd, J 6.1, 10.3 and 16.8, CH᎐CH ), 5.22 (1 H, dt,
᎐
2
J 17.1 and 1.3, CH H ᎐C), 5.06 (1 H, dt, J 10.3 and 1.2,
᎐
B
A
References
᎐
CH H ᎐C), 4.26 (1 H, br s, CHOH), 2.20 (2 H, m, CH C᎐C),
᎐
᎐
A
B
2
᎐
2.00 (1 H, t, J 2.6, HC᎐C), 1.55 (2 H, m, CH COH), 1.06 (3 H,
1 D. J. Ager and I. Fleming, J. Chem. Soc., Chem. Commun., 1978,
177.
2 Summarised in I. Fleming, in Organocopper Reagents: A Practical
Approach, ed. R. J. K. Taylor, OUP, Oxford, 1995, ch. 12, pp. 257–
292.
3 I. Fleming, T. W. Newton and F. Roessler, J. Chem. Soc., Perkin
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4 I. Fleming, M. Rowley, P. Cuadrado, A. M. González-Nogal and
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1981, 2520; I. Fleming and N. D. Kindon, J. Chem. Soc., Perkin
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7 N. Duffaut, J. Dunoguès, C. Biran and R. Calas, J. Organomet.
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8 A. Fürstner and H. Weidmann, J. Organomet. Chem., 1988, 354, 15.
9 J. G. Smith, S. E. Drozda, A. P. Petraglia, N. R. Quin, E. M. Rice,
B. S. Taylor and M. Viswanathan, J. Org. Chem., 1984, 49, 4112.
10 B. H. Lipshutz, D. C. Reuter and E. L. Ellsworth, J. Org. Chem.,
1989, 54, 4975.
11 R. D. Singer and A. Oehlschlager, J. Org. Chem., 1991, 56, 3510.
12 C. Nativi, A. Ricci and M. Taddei, Tetrahedron Lett., 1990, 31, 2637.
13 P. Auvray, P. Knochel and J. F. Normant, Tetrahedron, 1988, 44,
4495.
᎐
2
s, MeAMeBC) and 1.04 (3 H, s, MeAMeBC).
5,5-Dimethyloct-1-en-7-yn-3-yl acetate 1h. This was prepared
from 5,5-dimethyloct-1-en-7-yn-3-ol (0.70 g, 4.6 mmol), 4-
dimethylaminopyridine (0.35 g, 2.9 mmol), acetic anhydride
(0.63 g, 6.2 mmol, 0.60 cm3) and dichloromethane (8 cm3) as
in the preparation of the acetate 1g. Chromatography (SiO2,
EtOAc–hexane, 5:95) gave the acetate (0.61 g, 68%); Rf
(EtOAc–hexane,1:9) 0.36; νmax(film)/cmϪ1 3300 (᎐CH), 2120
᎐
᎐
᎐
(C᎐C), 1740 (C᎐O) and 1650 (C᎐C); δ (250 MHz; CDCl ) 5.76
᎐
᎐
᎐
H
3
(1 H, ddd, J 6.3, 10.4 and 17.0, CH᎐CH ), 5.37 (1 H, tddd,
᎐
2
J 1.2, 3.7, 6.3 and 8.7, CHCH᎐CH ), 5.20 (1 H, dt, J 17.2 and
᎐
2
1.1, CH H ᎐C), 5.11 (1 H, dt, J 10.4 and 1.0, CH H ᎐C), 2.10
᎐
᎐
B
A
B
A
᎐
(2 H, d, J 2.8, CH C᎐C), 2.04 (3 H, s, MeCO ), 1.99 (1 H, t,
J 2.7, HC᎐C), 1.75 (1 H, dd, J 8.6 and 14.8, CH H COAc),
᎐
2
2
᎐
᎐
A
B
1.60 (1 H, dd, J 3.7 and 14.8, CHAHBCOAc) and 1.00 (6 H, s,
Me2C) (Found: C, 74.45; H, 9.6. C12H18O2 requires C, 74.2; H,
9.35%).
Methyl (E)-5,5-dimethyloct-2-en-7-ynoate 1i. Following
Shing,36 methyl (triphenylphosphoranylidene)acetate (1.67 g,
5.0 mmol) was added in 10 portions over 15 min with stirring to
the aldehyde 1f (0.55 g, 4.4 mmol) in methanol (25 cm3) under
argon at 0 ЊC, and stirred for 1.5 h. The solvent was removed
under reduced pressure. The residue was chromatographed
(SiO2, EtOAc–hexane, 2:98) to give successively the cis-ester
(0.22 g, 27%); Rf (EtOAc–hexane, 1:9) 0.42; νmax(film)/cmϪ1
᎐
3310 (OH), 2130 (C᎐C), 1730 (C᎐O) and 1650 (C᎐C); δ (250
᎐
᎐
᎐
H
14 K. Takaki, T. Maeda and M. Ishikawa, J. Org. Chem., 1989, 54, 58.
15 M. Taddei and A. Mann, Tetrahedron Lett., 1986, 27, 2913;
P. Kocienski, S. Wadman and K. Cooper, J. Am. Chem. Soc., 1989,
111, 2363; M. Lautens, R. K. Belter and A. J. Lough, J. Org. Chem.,
1992, 57, 422.
16 I. Fleming and A. K. Sarkar, J. Chem. Soc., Chem. Commun., 1986,
1199.
17 J. H. M. Hill, unpublished work in Cambridge.
18 Y. Okuda, Y. Morizawa, K. Oshima and H. Nozaki, Tetrahedron
Lett., 1984, 25, 2483.
MHz; CDCl ) 6.26 (1 H, dt, J 7.8 and 11.7, CH CH᎐C), 5.87
᎐
3
2
(1 H, dt, J 1.6 and 11.7, C᎐CHCO Me), 3.69 (3 H, s, MeO),
᎐
2
2.71 (2 H, dd, J 1.6 and 7.8, CH CH᎐C), 2.11 (2 H, d, J 2.65,
᎐
2
᎐
᎐
CH C᎐C), 1.99 (1 H, t, J 2.65, HC᎐C) and 1.01 (6 H, s, Me C)
᎐
᎐
2
2
(Found: C, 73.2; H, 8.95. C11H16O2 requires C, 73.3; H, 8.95%),
and the trans-ester (0.38 g, 48%); Rf (EtOAc–hexane, 1:9) 0.33;
νmax(film)/cmϪ1 3310 (OH), 2130 (C᎐C), 1730 (C᎐O) and 1660
᎐
᎐
᎐
(C᎐C); δ (250 MHz; CDCl ) 6.95 (1 H, dt, J 7.8 and 15.5,
᎐
H
3
19 I. Fleming and E. Martínez de Marigorta, Tetrahedron Lett., 1993,
34, 1201.
20 P. J. Parsons, K. Booker-Milburn, S. H. Brooks, S. Martel and
M. Stefinovic, Synth. Commun., 1994, 24, 2159.
21 I. Fleming and T. W. Newton, J. Chem. Soc., Perkin Trans. 1, 1984,
1805.
22 I. Fleming, T. W. Newton, V. Sabin and F. Zammattio, Tetrahedron,
1992, 48, 7793.
23 G. Höfle and W. Steglich, Synthesis, 1972, 619.
24 J. Schreiber, D. Felix, A. Eschenmoser, M. Winter, F. Gautschi,
K. H. Schulte-Elte, E. Sundt, G. Ohloff, J. Kalvoda, H. Kaufmann,
P. Wieland and G. Anner, Helv. Chim. Acta, 1967, 50, 2101; D. Felix,
J. Schreiber, G. Ohloff and A. Eschenmoser, Helv. Chim. Acta, 1971,
54, 2896.
CH CH᎐C), 5.86 (1 H, dt, J 1.3 and 15.5, C᎐CHCO Me), 3.72
᎐
᎐
2
2
(3 H, s, MeO), 2.21 (2 H, dd, J 1.3 and 7.9, CH CH᎐C), 2.07
᎐
2
᎐
᎐
(2 H, d, J 2.6, CH C᎐C), 2.00 (1 H, t, J 2.6, HC᎐C) and 0.99 (6
᎐
᎐
2
H, s, Me2C) (Found: C, 73.45; H, 8.85).
2-(1,1-Dimethylbut-3-ynyl)oxirane 1c. Following Matteson,25
as with the oxirane 1e, 2,2-dimethylpent-4-ynal37 (0.74 g, 6.0
mmol) gave the epoxide (0.15 g, 18%); bp 50 ЊC/18 mmHg; Rf
(EtOAc–hexane,1:9) 0.95; νmax(film)/cmϪ1 3296 (᎐CH) and
᎐
᎐
᎐
2116 (C᎐C); δ (250 MHz; CDCl ) 2.84 (1 H, br t, J 3.4,
᎐
H
3
Me2CHO), 2.64 (2 H, m, CH2O), 2.18 (1 H, dd, J 2.6 and 16.7,
᎐
᎐
CH H C᎐C), 2.12 (1 H, dd, J 2.7 and 16.7, CH H C᎐C), 1.97
᎐
᎐
A
B
A
B
J. Chem. Soc., Perkin Trans. 1, 1999, 889–900
899

View Article Online
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Paper 8/09813A
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J. Chem. Soc., Perkin Trans. 1, 1999, 889–900