6948
A. B. E6ans, D. W. Knight / Tetrahedron Letters 42 (2001) 6947–6948
patible as a component of a reaction carried out in
tetrahydrofuran. We were delighted to find that this
seemingly simple change consistently delivered isolated
yields of homopropargylic alcohols of around 90%. The
reaction was successful with a range of both lithio-
acetylides as well as mono- and 1,2-disubstituted epox-
ides, including 1,2-epoxybutane, epichlorohydrin,
epoxycyclohexane, 3-(4-methoxyphenyl)-1,2-epoxypro-
pane and an example having a PMB function. The
resulting products 7–11 are shown below, along with
the isolated yields obtained in parenthesis.8
quenched by the addition of saturated aqueous ammo-
nium chloride (ꢀ5 ml per mmol of n-BuLi) and the
organic layer separated. The aqueous layer was then
extracted with ether (×3), and the combined organic
solutions were washed with brine, then dried (MgSO4)
and evaporated. The crude material was purified by
column chromatography on silica gel (20% ethyl acetate
in petroleum ether).
As expected, it was essential that samples of BF3·THF
complex 6 were carefully protected from moisture, in
which case material which was over six months old
(stored at 0°C) gave similarly high yields of alcohols 1.
Cl
R
OH
R
OH
We have not made any attempts to determine the
origins of these enhanced yields and can only speculate
that these may be due to the presumed extra stability of
complex 6 relative to BF3·OEt2. This could result in less
epoxide polymerisation which we assume is the primary
cause of loss of material.
7
R = Bu (93%)
R = Ph (92%)
8
R = Bu (88%)
R = Ph (94%)
R = TBDPSOCH2 (91%)
HO
R
OH
Acknowledgements
OMe
R
10 R = Bu (84%)
R = Ph (89%)
9
R = Bu (92%)
R = Ph (92%)
We thank the EPSRC Mass Spectrometry Service, Uni-
versity College, Swansea, for the provision of high
resolution mass spectral data and EPSRC for financial
support.
R = TBDPSOCH2 (88%)
R = Me3Si (95%)
OMe
References
O
TBDPSO
OH
11 (85%)
1. (a) Bedford, S. B.; Bell, K. E.; Bennett, F.; Hayes, C. J.;
Knight, D. W.; Shaw, D. E. J. Chem. Soc., Perkin Trans.
1 1999, 2143; (b) Jones, A. D.; Knight, D. W.; Hibbs, D.
E. J. Chem. Soc., Perkins Trans. 1 2001, 1182 and refer-
ences cited therein.
2. Fried, J.; Heim, S.; Etheredge, S. J.; Sunder-Plassman, P.;
Santhanakrishnan, T. S.; Himizu, J.; Lin, C. H. J. Chem.
Soc., Chem. Commun. 1968, 634.
In the original Yamaguchi–Hirao procedure,4 an excess
(1.5 equiv.) of both the acetylide and BF3·OEt2 was
used. A brief optimisation study using BF3·THF 6
revealed that a slight excess of the epoxide delivered the
best yields. A typical procedure, which otherwise
closely resembles the original is as follows:
3. Fried, J.; Lin, C. H.; Ford, S. H. Tetrahedron Lett. 1969,
1379.
4. Yamaguchi, M.; Hirao, I. Tetrahedron Lett. 1983, 24, 391.
5. Garratt, P. J. Comprehensive Organic Synthesis; Pergamon
Press: Oxford, 1991; Vol. 3, p. 271.
6. (a) Utimoto, K.; Lambert, C.; Fukuda, Y.; Shiragami, H.;
Nozaki, H. Tetrahedron Lett. 1984, 25, 5423; (b) Ooi, T.;
Morikawa, J.; Ichikawa, H.; Maruoka, K. Tetrahedron
Lett. 1999, 40, 5881.
7. Item 43, 428-0, Aldrich Chemical Co. Ltd.
8. Satisfactory spectroscopic and analytical data were
obtained for all products 7–11, along with literature com-
parisons.
n-Butyllithium (2.5 M solution in hexanes, 1.3 equiv.)
was added dropwise to a stirred solution of the 1-
alkyne (1.0 equiv.) in dry THF (ꢀ5 ml per mmol of
n-BuLi) under a nitrogen atmosphere at −78°C. The
resulting solution was stirred for 30 min, and then
treated dropwise with boron trifluoride–THF complex
(1.3 equiv.). After a further 15 min at −78°C, the
epoxide (1.2 equiv.) in dry THF (ꢀ1:1 relative to the
epoxide) was then added and the mixture stirred for
approximately
2 h at −78°C. The reaction was