Preparation of R,â-Unsaturated Aldehydes
J . Org. Chem., Vol. 65, No. 7, 2000 2159
t, 48.7 d, 55.2 q, 107.5 d, 127.3 d, 128.8, 129.9 s, 134.8 d. Anal.
Calcd for C18H30O2Se: C, 60.49; H, 8.46. Found: C, 60.38; H,
8.49.
chromatography (0.5% EtOAc in pentane) afforded the title
compound as a mixture of two diastereomers (3:2): 1H NMR
δ 0.82 and 0.85 (both d, Σ 6H, J ) 6.6 Hz), 0.95 and 1.08 (both
d, Σ 3H, J ) 6.5 and 6.9 Hz), 1.08-1.55 (several peaks, 8H),
3.22 and 3.29 (both dd, Σ 1H, J ) 6.2, 3.2 Hz and 7.1, 2.8 Hz),
3.34, 3.35, 3.36 and 3.37 (all s, Σ 6H), 4.52 and 4.53 (both d, Σ
1H, J ) 6.2 and 7.1 Hz), 7.18-7.26 (several peaks, 3H), 7.62
(m, 2H); 13C NMR δ 17.1 q, 18.1 q, 22.5 q, 22.6 q, 22.7 q, 24.9
t, 25.2 t, 27.9 d, 33.7 d, 33.9 t, 34.3 d, 35.9 t, 38.9 t, 39.0 t,
53.7 q, 54.1 q, 55.3 q, 55.6 q, 56.4 d, 57.2 d, 106.5 d, 107.2 d,
127.0 d, 128.8 d, 131.0 s, 131.2 s, 134.2 d, 134.4 d; 77Se NMR
δ 290.7 and 281.9.
2-(4-Ch lor oph en ylselen en yl)-1,1-dim eth oxyd eca n e was
prepared from compound 1c (0.665 mmol) and bis(4-chloro-
phenyl) diselenide according to the general procedure (9 h at
70 °C). The crude material contained 11% of unreacted
R-bromoacetal. Column chromatography (eluent 1.5% EtOAc
in pentane) afforded 0.168 g (64%) of the title compound: 1H
NMR δ 0.87 (t, 3H), 1.18-1.31 (several peaks, 10H), 1.39 (m,
1H), 1.55 (m, 2H), 1.77 (m, 1H), 3.19 (dd, 1H, J ) 7.8, 5.0 Hz),
3.38 (s, 3H). 3.40 (s, 3H), 4.36 (d, 1H, J ) 5.0 Hz), 7.22 (d, 2H,
J ) 8.4 Hz), 7.52 (d, 2H, J ) 8.4 Hz); 13C NMR δ 14.1 q, 22.6
t, 27.6 t, 29.2 t, 29.4 t (two peaks), 30.3 t, 31.8 t, 49.3 d, 55.2
q, 55.5 q, 107.4 d, 128.0 s, 129.0 d, 133.6 s, 136.1 d. Anal. Calcd
for C18H29ClO2Se: C, 55.17; H, 7.46. Found: C, 54.94; H, 7.35.
1,1-Dim et h oxy-2-(4-m et h oxyp h en ylselen en yl)d eca n e
was prepared from compound 1c (1 mmol) and bis(4-methoxy-
phenyl) diselenide according to the general procedure (9 h at
75 °C gave complete consumption of 1c). Column chromatog-
raphy (1-4% ether in pentane) afforded 0.318 g (82%) of the
title compound as a colorless oil: 1H NMR δ 0.87 (t, 3H, J )
6.8 Hz), 1.18-1.33 (several peaks, 10H), 1.36-1.58 (several
peaks, 3H), 1.72 (m, 1H), 3.10 (m, 1H), 3.37 (s, 3H), 3.39 (s,
3H), 3.80 (s, 3H), 4.34 (d, 1H, J ) 5.3 Hz), 6.80 (d, 2H, J ) 8.8
Hz), 7.54 (d, 2H, J ) 8.8 Hz); 13C NMR δ 14.1 q, 22.7 t, 27.6 t,
29.3 t, 29.4 t (two peaks), 29.9 t, 31.9 t, 48.7 d, 55.0 q, 55.1 q,
55.2 q, 107.2 d, 114.5 d, 119.2 s, 137.4 d, 159.5 s. Anal. Calcd
for C19H32O3Se: C, 58.90; H, 8.33. Found: C, 58.81, H, 8.47.
10,10-Dim et h oxy-9-p h en ylselen en yld eca n ol (3d ) was
prepared from bromoacetal 1d (0.202 g, 0.68 mmol), diphenyl
diselenide (0.125 g, 0.4 mmol), freshly powdered K2CO3 (0.5
g), and DMSO (1.5 mL) according to the general procedure
(90 °C, 8 h). Column chromatography (5, 20, and 35% EtOAc
in pentane) afforded 0.221 g (87%) of the title compound as a
colorless oil: 1H NMR δ?1.20-1.45 (several peaks, 10H), 1.48-
1.53 (several peaks, 4H), 1.79 (m, 1H), 3.22 (m, 1H), 3.38 (s,
3H), 3.41 (s, 3H), 3.62 (t, 2H, J ) 6.7 Hz), 4.38 (d, 1H, J ) 4.8
Hz), 7.22-7.28 (several peaks, 3H), 7.59 (m, 2H); 13C NMR δ
25.7 t, 27.6 t, 29.2 t, 29.3 t, 30.1 t, 32.8 t, 48.8 d, 55.4 q, 63.0
t, 107.5 d, 127.3 d, 128.8 d, 129.8 s, 134.7 d. Anal. Calcd for
2-Ben zyloxy-3-p h en ylselen en yltetr a h yd r op yr a n (3h ).
The crude product was an inseparable 1:3 mixture of the title
1
compound and acetal 4h . H NMR data for the selenide were
in good agreement with literature.20
2-Cycloh e xyl-1,1-d im e t h oxy-2-p h e n ylse le n e n yle t h -
a n e (3i). The crude material was a 96:4 mixture of the title
compound and unsaturated acetal 4i. Column chromatography
(eluent 1% EtOAc in pentane) afforded 0.288 g (88%) of the
selenide 3i as a colorless oil: 1H NMR δ 1.04-1.36 (several
peaks, 4H), 1.45-1.95 (several peaks, 7H), 3.13 (dd, 1H, J )
6.1, 3.4 Hz), 3.34 (s, 3H), 3.38 (s, 3H), 4.51 (d, 1H, J ) 6.1
Hz), 7.19-7.28 (several peaks, 3H), 7.61 (m, 2H); 13C NMR δ
26.2 t, 26.3 t, 26.4 t, 30.3 t, 31.8 t, 39.2 d, 54.6 q, 55.4 q, 57.3
d, 106.8 d, 126.9 d, 128.8 d, 131.5 s, 134.0 d. Anal. Calcd for
C
16H24O2Se: C, 58.71; H, 7.39. Found: C, 58.56; H, 7.33.
3-Cycloh e xyl-1,1-d im e t h oxy-2-p h e n ylse le n e n ylp r o-
p a n e (3j) was prepared essentially (0.78 mmol of Ph2Se2 was
used at 90 °C and 9 h) according to the general procedure.
The crude material was an 88:12 mixture of the title compound
and 3-cyclohexyl-1,1-dimethoxy-2-propene (4j). Column chro-
matography (1% EtOAc in pentane) afforded the pure title
compound: yield 78% in 1 mmol scale; 1H NMR δ 0.90 (m,
2H), 1.06-1.29 (several peaks, 4H), 1.48 (m, 1H), 1.53-1.78
(several peaks, 6H), 3.30 (m, 1H), 3.37 (s, 3H), 3.41 (s, 3H),
4.32 (d, 1H, J ) 5.0 Hz), 7.21-7.28 (several peaks, 3H), 7.60
(m, 2H); 13C NMR δ 26.0 t, 26.3 t, 26.5 t, 32.2 t, 34.0 t, 35.2 d,
37.4 t, 46.1 d, 55.4 q, 55.5 q, 107.9 d, 127.4 d, 128.8 d, 129.6 s,
134.9 d. Anal. Calcd for C17H26O2Se: C, 59.82; H, 7.68.
Found: C, 59.80; H, 7.81.
C
18H30O3Se: C, 57.90; H, 8.10. Found: C, 57.64; H, 7.96.
2-(1-P h en ylselen en ylh ep tyl)-1,3-d ioxola n e (3e). Puri-
1,1-Dim eth oxy-3-ph en yl-2-ph en ylselen en ylpr opan e (3k).
The reaction of 2-bromo-1,1-dimethoxy-3-phenylpropane (1k )
with PhSeK according to the general procedure afforded an
inseparable 1:1 mixture of the title compound and cinnamic
aldehyde dimethyl acetal (4k ). The crude product was hydro-
lyzed in an acetone-water mixture (3:1, 4 mL) in the presence
of oxalic acid (0.1 g) for 2 h at ambient temperature. Extractive
workup and column chromatography (1% EtOAc in pentane)
afforded the known 2-phenylselenenyl-3-phenylpropanal (NMR
data were in close agreement with literature6). Acetalization
with MeOH in the presence of p-toluenesulfonic acid afforded
the title product 4f (90% purity, the major contaminant was
1,1-dimethoxy-3-phenylpropane): 1H NMR δ 2.92 (dd, 1H, J
) 14.2, 8.2 Hz), 3.23 (dd, 1H, J ) 14.2, 6.1 Hz), 3.41 (s, 6H),
3.48 (m, 1H), 4.34 (d, 1H, J ) 4.0 Hz), 7.20-7.35 (several
peaks, 8H), 7.45 (m, 2H); 13C NMR δ 37.0 t, 50.2 d, 55.8 q,
106.8 d, 126.3 d, 127.3 d, 128.2 d, 129.0 d, 129.3 d, 129.7 s,
134.7 d, 139.6 d; 77Se NMR δ 343.3.
1,1-Dim e t h oxy-2-p h e n ylse le n e n yl-3,3-d im e t h ylb u -
ta n e (3m ) was prepared in 46% yield essentially according to
the general procedure (120 °C for 8 h; at 70 °C the compound
is not formed) and purified by column chromatography (eluent
1% Et2O and 1% Et3N in pentane): 1H NMR δ 1.09 (s, 9H),
2.97 (d, J ) 1.6 Hz, 1H), 3.41 (s, 3H), 3.47 (s, 3H), 4.47 (d, J
) 1.6 Hz, 1H), 7.18-7.23 (several peaks, 3H), 7.63 (m, 2H);
13C NMR δ 29.0 q, 35.0 s, 56.2 q, 56.3 q, 64.4 d, 106.6 d, 126.7
d, 128.7 d, 132.9 s, 134.1 d; 77Se NMR δ 284.5. Anal. Calcd for
C14H22O2Se: C, 55.81; H, 7.36. Found: C, 55.56; H, 7.28.
fied by column chromatography (eluent 2% EtOAc in pen-
1
tane): yield 93%; H NMR δ 0.88 (t, 3H), 1.19-1.32 (several
peaks, 6H), 1.42 (m, 1H), 1.63 (m, 2H), 1.82 (m, 1H), 3.25 (m,
1H), 3.91 (m, 2H), 4.08 (m, 2H), 5.08 (d, 1H, J ) 5.0 Hz), 7.21-
7.31 (m, 3H), 7.60 (m, 2H); 13C NMR δ 13.9 q, 22.4 t, 27.6 t,
28.9 t, 30.4 t, 31.5 t, 49.6 d, 65.4 t, 65.6 t, 105.6 d, 127.2 t,
128.8 t, 129.9 s, 134.4 d. Anal. Calcd for C16H24O2Se: C, 58.75;
H, 7.40. Found: C, 59.02; H, 7.88.
1,1-Dim eth oxy-3-eth yl-2-p h en ylselen en ylh ep ta n e (3f).
The crude product was an inseparable mixture of the title
compound and acetal 4f. Hydrolysis in an acetone-water
mixture (3:1, 4 mL) in the presence of oxalic acid (0.1 g) for 2
h at ambient temperature, extractive workup, and column
chromatography (0.5% EtOAc in pentane) allowed separation
of the corresponding aldehydes. 3-Ethyl-2-phenylselenohep-
tanal thus obtained was acetalized with CH(OMe)3 and
subjected to column chromatography to afford a purer (ca. 90%)
title compound as a mixture of two diastereomers (1:1): 1H
NMR δ 0.80-0.95 (several peaks, 6H), 1.12-1.70 (several
peaks, 9H), 3.35 (m, 1H), 3.34 and 3.35 (both s, Σ 6H), 4.55
and 4.57 (both d, Σ 1H, J ) 6.9 and 7.0 Hz), 7.19-7.28 (several
peaks, 3H), 7.62 (m, 2H); 13C NMR δ 12.1 q, 12.3 q, 14.0 q,
22.8 t, 24.6 t, 24.7 t, 29.7 t, 29.9 t, 31.0 t, 31.4 t, 40.7 d, 40.8
d, 53.3 q, 53.5 q, 53.9 q, 54.2 q, 55.5 d, 106.9 d, 107.0 d, 127.0
d, 128.7 d, 131.2 s, 134.3 d; 77Se NMR δ 290.7 and 291.9.
1,1-Dim e t h oxy-3,7-d im e t h yl-2-p h e n ylse le n e n yloc-
ta n e (3g). The crude product was an inseparable 1:1 mixture
of the title compound and acetal 4g. A purer (ca. 90%) sample
of compound 3g was prepared as described for compound 3f
(acidic hydrolysis of acetals 3g and 4g, separation of aldehydes
by column chromatography, and reacetalization of 2-phenylse-
lenenyl-3,7-dimethyloctanal thus obtained). Final column
The aqueous phase obtained during workup was acidified
with HCl (pH ) 1), extracted with ether, dried, and concen-
trated in vacuo. NMR analysis of the residue showed, except
for Ph2Se2, the presence of 3,3-dimethylbutyric acid: 1H NMR