PAPER
Synthesis of Homoallylic Alcohols
3463
removed under reduced pressure and the obtained crude homoallyl-
ic alcohol products were purified by column chromatography (silica
gel 60–120 mesh). The pure products were confirmed by their H
Table 2 A Study of the Catalyst System for the Reaction of Benz-
aldehyde (1a) with Allyl Bromide (2)
1
Entry
CdCl2
Mg
Solvent
Yield (%)
NMR, IR, and MS data.
(equiv)
(equiv)
of 3a
1-Phenylbut-3-en-1-ol (3a)
Colorless oil.
1
2
3
4
5
6
0
0
1
1
1
1
1.5
2.0
1.5
2.0
1.5
2.0
THF
65
49
56
50
93
89
IR (neat): 3416, 3081, 2965, 2853, 1647, 1508, 1459, 1263, 1104,
971, 759, 732 cm–1.
1H NMR (CDCl3): d = 2.18 (br s, 1 H), 2.37–2.43 (m, 2 H), 4.63 (t,
J = 6.0 Hz, 1 H), 5.05–5.20 (m, 2 H), 5.35–5.70 (m, 1 H), 7.27–7.40
(m, 5 H).
MS (EI): m/z (%) = 148 (M+ 12), 130 (10), 115 (15), 107 (100), 91
(20), 79 (54), 63 (25), 51 (33).
THF
THF
THF
THF–H2O
THF–H2O
1-(2-Furyl)but-3-en-1-ol (3c)
Colorless oil.
Table 3 A Comparative Study on the Bimetallic Catalyst Systems
for the Reaction of Benzaldehyde (1a) with Allyl Bromide (2)
IR (neat): 3391, 3076, 2951, 2843, 1645, 1568, 1504, 1435, 1347,
1261, 1138, 1055, 948, 867, 739 cm–1.
1H NMR (CDCl3): d = 1.98 (br s, 1 H), 2.60 (t, J = 5.0 Hz, 2 H), 4.70
(t, J = 6.0 Hz, 1 H), 5.10–5.20 (m, 2 H), 5.70–5.80 (m, 1 H), 6.21
(dd, J = 3.5 Hz, 1 H), 6.31 (d, J = 3.5 Hz, 1 H), 7.35 (d, J = 2.0 Hz,
1 H).
Entry
MX
(equiv)
M
(equiv)
Solvent
system
Yield (%)
of 3a
1
2
3
4
5
6
BiCl3
Mg
THF–H2O
DMF–H2O
THF
73
89
56
50
93
89
SbCl3
Fe
MS (EI): m/z (%) = 138 (M+, 18), 119 (62), 96 (38), 91 (100), 89
(26), 77 (15), 63 (18), 49 (12), 29 (31).
CdCl2 (1)
CdCl2 (1)
CdCl2 (1)
CdCl2 (1)
Mg (1.5)
Mg (2.0)
Mg (1.5)
Mg (2.0)
THF
(E)-1-Phenylhexa-1,5-dien-3-ol (3d)
Colorless oil.
1H NMR (CDCl3): d = 1.60 (br s, 1 H), 2.35–2.45 (m, 2 H), 4.32 (q,
J = 6.5 Hz, 1 H), 5.18 (t, J = 6.5 Hz, 2 H), 5.78–5.90 (m, 1 H), 6.20
(dd, J = 16.0, 6.0 Hz, 1 H), 6.58 (d, J = 16.0 Hz, 1 H), 7.18–7.38 (m,
5 H).
THF–H2O
THF–H2O
The scope and generality of this methodology was studied
with various aldehydes and the obtained results are illus-
trated in Table 1.
1-Phenylhex-5-en-3-ol (3g)
Colorless oil.
In conclusion, we have described a simple, convenient,
and efficient method for the preparation of homoallylic al-
cohols by the reaction of various aldehydes and allyl bro-
mide in the presence of the magnesium–cadmium
chloride reagent system. The salient features of this meth-
odology are high conversions, mild reaction conditions,
and simplicity of operation.
1H NMR (CDCl3): d = 1.60–1.70 (m, 2 H), 1.80 (br s, 1 H), 2.05–
2.20 (m, 2 H), 2.65–2.75 (m, 2 H), 3.50–3.60 (m, 1 H), 4.95–5.05
(m, 2 H), 5.65–5.75 (m, 1 H), 7.05–7.20 (m, 5 H).
1-(4-Methylphenyl)but-3-en-1-ol (3j)
Colorless oil.
1H NMR (CDCl3): d = 1.96 (br s, 1 H), 2.30 (s, 3 H), 2.43–2.50 (m,
2 H), 4.65 (t, J = 6.0 Hz, 1 H), 5.05–5.15 (m, 2 H), 5.70–5.80 (m, 1
H), 7.06 (d, J = 7.5 Hz, 2 H), 7.19 (d, J = 7.5 Hz, 2 H).
IR spectra were recorded on a Perkin-Elmer FT-IR 240C spectro-
1
meter. H NMR spectra were recorded on a Gemini-200 spectro-
1-Cyclohexylbut-3-en-1-ol (3l)
Colorless oil.
1H NMR (CDCl3): d = 0.90–1.20 (m, 6 H), 1.60–1.70 (m, 5 H), 1.80
(br s, 1 H), 2.10–2.30 (m, 2 H), 3.30–3.40 (m, 1 H), 5.05–5.15 (m,
2 H), 5.75–5.85 (m, 1 H).
meter in CDCl3 using TMS as internal standard. Mass spectra were
measured on a Finnigan MAT 1020 mass spectrometer operating at
70 eV. All compounds are known and have spectroscopic data iden-
tical to that in the literature.1d,3f,4b,4d
1-Substituted But-3-en-1-ols 3; General Procedure
To a stirred mixture of Mg turnings (1.5 equiv) and CdCl2 (1.0
equiv) in THF–H2O (8:2, 10 mL) was added allyl bromide (2, 1.0
equiv) and the mixture was stirred for 20 min. The aldehyde 1 (1.0
equiv) was added and the resulting mixture was stirred for the spec-
ified period (Table 1) at 25 °C. When the reaction was complete
(TLC), the solvent was removed under reduced pressure. To the res-
idue obtained was added EtOAc (10 mL) and H2O (10 mL) and the
mixture was stirred well and extracted with EtOAc. The organic
layer was washed with brine and dried (Na2SO4). The EtOAc was
References
(1) (a) Barczak, N. T.; Grote, R. E.; Jarvo, E. R.
Organometallics 2007, 26, 4863. (b) Suginome, M.; Ito, Y.
J. Organomet. Chem. 2003, 680, 43. (c) Nagano, Y.; Orita,
A.; Otera, J. Adv. Synth. Catal. 2003, 345, 643.
(d) Aggarwal, V. K.; Vennall, G. P. Synthesis 1998, 1822.
(e) Ollevier, T.; Li, Z. Org. Biomol. Chem. 2006, 4440.
(f) Masuyama, Y.; Chiyo, T.; Kurusu, Y. Synlett 2005, 2251.
Synthesis 2008, No. 21, 3461–3464 © Thieme Stuttgart · New York