N. G. Bhat et al. / Tetrahedron Letters 48 (2007) 4267–4269
4269
7
8
. Langkopf, E.; Schinzer, D. Chem. Rev. 1995, 95, 1375.
. Streiff, S.; Ribeiro, N.; D e´ saubry, L. J. Org. Chem. 2004,
subsequent vacuum pump were applied to remove excess
ether. To the resulting solution were added 50 mL pentane
and 1 mL 1,3-propanediol and stirred for an hour. The
product was decanted and washed with pentane, and the
excess solvent removed through evaporation and vacuum
pump again. The crude product was further purified by
column chromatography using alumina and pentane.
NMR and IR analyses confirmed the synthesis of (Z)-1-
alkenylboronate ester.
6
9, 7592.
. Barbero, A.; Pulido, F. J. Acc. Chem. Res. 2004, 37,
17.
9
8
1
0. Brown, H. C.; Basavaiah, D.; Kulkarni, S. U.; Bhat, N.
G.; Prasad, J. V. N. V. J. Org. Chem 1988, 53, 239.
1. Kamachi, T.; Kuno, A.; Matsuno, C.; Okamoto, S.
Tetrahedron Lett. 2004, 45, 4677.
1
1
1
2. Sawaki, R.; Sato, Y.; Mori, M. Org. Lett. 2004, 6, 1131.
3. O’Donnell, M. J.; Drew, M. D.; Cooper, J. T.; Delgado,
F.; Zhou, C. J. Am. Chem. Soc. 2002, 124, 9348.
4. Gorman, J. S. T.; Lacono, S. T.; Pagenkopf, B. L. Org.
Lett. 2004, 6, 67.
5. Chakraborty, D.; Rodriguez, A.; Chen, E. Y.-X. Macro-
melecules 2003, 36, 5470.
6. Shimada, T.; Aoki, K.; Shinoda, Y.; Nakamura, T.;
Tokunaga, N.; Inagaki, S.; Hayashi, T. J. Am. Chem. Soc.
(Z)-4-Phenyl-1-butenyl boronate ester: PMR (CDCl3/
TMS): d 1.96–3.19 (m, 6H), 4.05 (m, 4H), 5.34 (m, 1H),
6.69 (m, 1H) and 7.28 ppm (m, 5H). CMR (CDCl /TMS):
3
d 27.51, 33.56, 36.28, 61.67, 61.82, 76.85, 77.27, 77.69,
125.83, 128.35, 128.69, 142.34, and 151.38 ppm. The newly
synthesized (Z)-4-phenyl-1-butenyl boronate ester was
redissolved in 10 mL of ether and allowed to stir with
1
1
1
10 mmol trimethylsilylmethyllithium at ꢀ78 °C in
a
100 mL round-bottomed flask for a few hours. To the
resulting solution was added 10 mmol iodine dissolved in
methanol and allowed to stir overnight. Workup followed
by purification over column chromatography provided the
corresponding (E)-allyltrimethylsilane. The spectral data
confirmed its identity.
2
003, 125, 4688.
7. Brown, H. C.; Bhat, N. G.; Somayaji, V. Organometallics
983, 2, 1311.
1
1
1
1
8. Brown, H. C.; Imal, T. Organometallics 1984, 3, 1392.
9. The synthesis of 5-phenyl-2-(E)-pentenyl-1-trimethylsilane
is representative: The a-bromo-(Z)-1-alkenylboronate
5-Phenyl-2-(E)-pentenyl-1-trimethylsilane: PMR (CDCl
no TMS): d 0.058 (s, 9H), 1.44–2.82 (m, 6H), 5.45 (m, 1H),
6.27 (m, 1H) and 7.33 ppm (m, 5H). CMR (CDCl /no
3
/
1
7
ester was prepared as described by Brown et al. To
1
0 mmol of a-bromo-(Z)-4-phenyl-1-butyl boronate ester
3
1
8
(
1.9 mL) was added KIPBH (12 mmol, 12 mL) at 0 °C in
TMS): d ꢀ1.81, 22.00, 34.22, 36.53, 126.24, 128.37, 128.60,
a nitrogen-fixed 100 mL round-bottomed flask equipped
with magnetic stir bar. The mixture was allowed to stir
overnight, then reacted with excess water to remove
byproduct triisopropoxyborane. The product was then
extracted with 75 mL ether and 100 mL water, then
washed twice with 25 mL water. Evaporation and
and 140.377 ppm. IR: t 1495 (aromatic region) and
ꢀ
1
1603 cm (C@C).
20. In a mixture of isomers, the vinylic carbons of the (Z)-
alkenes can be distinguished from the corresponding
carbons of (E)-alkenes. Dorman, D. E.; Jautelat, M.;
Roberts, J. D. J. Org. Chem 1971, 36, 2757.