March 1998
SYNTHESIS
291
Table 3. Compounds 4a–c, 5b, 6b and 6d Prepareda
Product
Yield
(%)
1H NMR (CDCl3)
dZ (major), J (Hz)
13C NMR (CDCl3)
dZ (major), JC-F (Hz)
19F NMR
(CDCl3/
CFCl3)
d
IR
(KBr/Film)
nC=C
,
n
C=O or
n
OH (cm–1)
4a
56
50
1.3 (t, J = 7, 3H), 1.5 (bs, 1H,
OH), 2.4 (m, 2H), 2.7 (m, 2H)
3.8 (m, AB system, J = 7, J = 7,
2H), 6.0 (s, 1H), 7.0–7.6 (m,
10H)
15.3, 28.5, 37.0, 70.1 (q, 4J = 1),
71.6 (C-OH), 122.0 (q, 1J = 278,
CF3), 126.0, 127.1, 128.0, 129.0,
136.7 (q, 3J = 2.5, CCF3), 140.5 (q,
2J = 33), 141,5, 141.6 (q, J = 1, CF3),
141.6
–62.1/–58.2
(Z/E 90:10)
1656,
3457
4b
0.8 (m, 3H), 1.2 (m, 11H), 2.0
(m, 2H), 2.5 (d, J = 5, OH), 3.6
and 3.7 (m, AB system, J = 7.3,
J = 7, 2H), 5.7 (d, J = 5, 1H), 7.3
(m, 5H)
13.9, 15.0, 22.5, 26.9, 29.6, 30.1,
31.2, 69.8 (q, 4J = 1), 71.5 (COH),
122.0 (q, J = 278, CF3), 125.7,
127.3, 128.2, 137.9 (q, 3J = 2.7,
CCCF3), 140.3 (q, 2J = 32, CCF3),
141.9 (q, 4J = 1, COH)
–61.9/–58.2
(Z/E 90:10)
1673,
3451
4c
30
60
1.3 (t, J = 7, 3H), 2.2 (d, J = 8,
OH), 4.0 (m, AB system, J = 7, J =
7, 2H), 6.0 (d, J = 8, 1H), 6.75 (m,
2H), 7.2 (m, 8H)
15.4, 70.2 (q, 4J = 1), 71.3 (COH),
122.0 (q, 1J = 279, CF3), 125.8,
127.6, 127.7, 128.1, 129.6, 131.9,
137.0 (q, 3J = 2.5, CCCF3), 140.8
(q, 2J = 32, CCF3), 141.2
–60.6 (Z)
1656,
3460
5b
0.8 (m, 3H), 0.95 (t, J = 7, 3H),
1.2 (m, 11H), 1.6 (m, 2H), 2.0
(m, 2H + 1H), 3.7 (m, AB system,
J = 7, J = 7, 2H), 4.4 (Z)/4.5 (m,
1H)
10.4, 14.1, 15.3, 22.7, 26.5, (q, J=
2), 29,1, 29.9, 30.5 (q, J = 1.5),
31.6, 70.5 (q, J = 2), 72.6 (CoH),
120.0 (q, 1J = 278, CF3), 138.6 (q,
3J = 2.7, CCCF3), 139.5 (q, 2J = 32,
CCF3)
–61.9/–59.0
(Z/E 90:10)
1656,
3448
6b
6d
56
48
0.87 (t, J = 7, 3H), 1.25 (m, 14H),
2.3 (m, 2H), 3.7 (q, J = 7), 4.2 (q,
J = 7)
13.9, 14.1, 15.0, 22.4, 27.5 (q, J =
2), 28.2, 28.8, 61.2, 70.8, 121.0 (q,
1J = 278, CF3), 130.0 (q, 3J = 2.7,
CCCF3), 143.0 (q, 2J = 32, CCF3),
167.2
–63.6 (Z)
–62.2 (Z)
668,
1734
1.3 (m, 12H), 1.6 (m, 4H), 2.5
(m, 1H), 3.8 (q, J = 7, CH2O), 4.2
(q, J = 7, CH2O)
14.2, 15.0, 25.5, 26.0, 31.3, 36.5,
61.0, 70.5, 121.5 (q, 1J = 279, CF3),
135.1 (q, 3J = 2.3, CCCF3), 140.5
(q, 2J = 34, CCF3), 166.4 (C=O)
1662,
1733
a Satisfactory microanalyses obtained: C ´ 0.3, H ´ 0.2.
in anhyd Et2O (25mL) at r.t. under argon. After 30 min the solution
was filtered through Celite and evaporated to give a brown oil which
was further purified by chromatography (CH2Cl2) to give 3a (Z/E
90:10) (2.09 g, 92.5%) as a colorless oil.
was stirred for a further 15 min at –78 °C and was allowed to warm to
r.t. The mixture was quenched with sat. NH4Cl and extracted with
CH2Cl2 (2 ´ 25 mL). The combined organic phases were dried
(MgSO4) and evaporated to give a mixture of 4a and 1a (70:30).
These products were then separated by chromatography (silica gel,
pentane/Et2O 80:20) to give (Z/E-1a (22 mg, 20%) and 4a (Z/E
90:10)(90 mg, 56%).
(E)-2-Ethoxy-1,1,1-trifluoro-5-phenylpent-2-ene (1a); Typical
Procedure:
1.5 M t-BuLi in hexanes (0.6 mL, 0.92 mmol) was added to a solution
of 3a (Z/E 90:10)(150 mg, 4.6 ´ 10–4 mol) in THF at –78 °C under ar-
gon. The solution was stirred for a further 15 min at –78 °C and al-
lowed to warm to r.t. before hydrolysis with sat. NH4Cl. The mixture
was extracted with CH2Cl2 (2 ´ 25 mL). The combined organic phas-
es were dried (MgSO4) and evaporated to give a yellow oil which
was purified by chromatography (silica gel, pentane/Et2O 90:10) to
give 1a (E/Z 90:10) (84 mg, 75%). Same results were obtained when
the reaction was performed in Et2O (15 mL)/TMEDA (53 mg,
1 equiv).
(1) Bégué, J. P.; Bonnet-Delpon, D.; M’Bida, A.; Wu, S. W.;
Shintani, T.; Nakai, T. Tetrahedron Lett. 1994, 35, 2907.
Bégué, J. P.; Benayoud, F.; Bonnet-Delpon, D.; Fischer-Du-
rand, N.; Sdassi, H. Synthesis 1993, 1083.
Bégué, J. P.; Bonnet-Delpon, D.; Lequeux, T. J. Chem. Soc.,
Perkin Trans. I 1991, 2889.
(2) Bégué, J. P.; Bonnet-Delpon, D.; Rock, M. H. Tetrahedron Lett.
1996, 37, 257.
Bégué, J. P.; Bonnet-Delpon, D.; Bouvet, D.; Rock, M. H. J.
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Enders, D.; Karl, W. Synlett 1992, 895.
2-Ethoxy-1,1,1-trifluoro-3-[hydroxy(phenyl)methyl]-5-phenyl-
pent-2-ene (4a); Typical Procedure:
1.5 M t-BuLi in hexanes (0.6 mL, 0.92 mmol) was added to a solution
of 3a (150 mg, 4.6 ´ 10–4 mol) in Et2O in the presence of TMEDA
(57 mg, 4.6 ´ 10–4 mol) at –78 °C under argon. After 1 min at –78 °C
the benzaldehyde (43 mg, 4.6 ´ 10–4 mol) was added. The solution
Enders, D.; Hecker, P.; Meyer, O. Tetrahedron 1996, 52, 2909.