Methylene-THF and Cyclobutanols from γ-Oxide Ylides
phenylborate for conversion into its tetraphenylborate: color-
less crystals; mp 188-189 °C. Found: C, 85.00; H, 6.51. Calcd
for C46H42BOP: C, 84.67; H, 6.44.
(d, 1H, CHH), 4.95 (m, 1H, PhCH), 4.96 (m, 1H, dCH), 5.03
(m, 1H, dCH), 7.27-7.38 (m, 5H, Ph). 13C NMR (CDCl3) δ
41.11 (CH2), 71.31 (OCH2), 81.07 (PhCH), 104.33 (dCH2),
125.85, 127.53, 128.35, 141.76 (Ph), 147.88 (dC). HRMS calcd
for C11H12O: M+ 160.0888. Found: M+ 160.0878.
P r ep a r a tion of 3-Hyd r oxy-4-iod obu tyltr ip h en ylp h os-
p h on iu m Iod id e (11). To a refluxing solution of 1,4-dichloro-
2-butanol (1.55 g, 11 mmol) and lithium iodide (2.60 g, 20
mmol) in THF (10 mL) was added a solution of triphenylphos-
phine (2.89 g, 11 mmol) in benzene (20 mL). After 12 h of
refluxing, colorless oily crystals were precipitated. The result-
ing suspension was evaporated to give pale yellow oily crystals,
which was dissolved in dichloromethane and filtered. The
filtrate was evaporated to give an orange oil, which was
washed with ether (10 mL × 2). This oil was solidified upon
standing. The resulting pale yellow crystals were recrystallized
from methanol-ether to afford colorless crystals of 11 (3.34
g, 5.8 mmol, 53%). 3-Hydroxy-4-iodobutyltriphenylphos-
phonium iodide (11): mp 166-168 °C. 1H NMR (CDCl3) δ
1.88-1.95 (m, 1H, CHH), 2.03-2.16 (m, 1H, CHH), 3.28-3.39
(m, 2H, CH2I), 3.65-3.92 (m, 2H, P-CH2), 4.07-4.18 (m, 1H,
CHOH), 4.52 (d, 2H, J ) 7 Hz, CHOH), 7.60-7.90 (m, 15H,
Ph). 13C NMR (CDCl3) δ 12.80 (CH2I), 20.10 (d, P-CH2), 29.09
(CH2), 69.14 (CHOH), 117.48, 118.34, 130.64, 133.57, 135.58
(Ph). Found: C, 44.92; H, 3.94. Calcd for C22H23I2OP: C, 44.86;
H, 3.91.
Rea ction of 11 w ith Bu tyllith iu m F ollow ed by th e
Ad d ition of Ben za ld eh yd e. To a suspension of 11 (2.35 g,
4.0 mmol) in THF (35 mL) was added a solution of butyllithium
(1.6 M in hexane, 5.5 mL, 8.8 mmol) in hexane at 0 °C via
syringe. After 2 h of stirring, a solution of benzaldehyde (0.42
g, 4.0 mmol) was added to this solution at -40 °C. After being
stirred for 3 h, the reaction mixture was warmed to room
temperature. The resulting solution was washed with water,
dried over magnesium sulfate, and evaporated to give a brown
oil. The residue was chromatographed over silica gel by elution
from hexanes-ethyl acetate to afford cyclobutanol, 5a , in 48%
yield (0.31 g, 1.92 mmol).
R ea ct ion of 3-H yd r oxya lk ylt r ip h en ylp h osp h on iu m
Br om id e w ith Bu tyllith iu m F ollow ed by th e Ad d ition
of P a r a for m a ld eh yd e. To a suspension of 3-hydroxy-3-
phenyltriphenyphosphonium bromide (12a , 0.955 g, 2 mmol)
in THF (30 mL) was added butyllithium THF solution (1.6 M,
2.8 mL, 4.4 mmol) at -20 °C, and the mixture was stirred for
30 min. The resulting red solution was warmed to room
temperature, and paraformaldehyde (0.30 g, 10 mmol) was
added in one portion. After being stirred for 5 h, the reaction
mixture was washed with water, dried over magnesium
sulfate, and finally evaporated to afford a colorless oil. This
oil was extracted with hexane to separate triphenylphosphine
oxide. The hexane extract was evaporated and chromato-
graphed over silica gel by hexan--dichloromethane to give 2a
(0.22 g, 1.5 mmol).15 1H NMR (CDCl3) δ 2.51 (m, 2H, CH2),
4.72 (m, 1H, CH), 5.17 (m, 2H, dCH2), 5.80 (m, 1H, dCH),
7.24-7.38 (m, 5H, Ph).
In Reflu xin g THF . To a suspension of 3-hydroxy-3-phenyl-
triphenyphosphonium bromide (12a , 0.955 g, 2 mmol) in THF
(30 mL) was added butyllithium THF solution (1.6 M, 2.8 mL,
4.4 mmol) at -20 °C, and the mixture was stirred for 30 min.
The resulting red solution was warmed to 40 °C, and paraform-
aldehyde (0.30 g, 10 mmol) was added in one portion. After
refluxing for 1 h, the reaction mixture was washed with water,
dried over magnesium sulfate, and finally evaporated to afford
a colorless oil. This oil was extracted with hexane to separate
triphenylphosphine oxide. The hexane extract was evaporated
and chromatographed over silica gel by hexane-dichloro-
methane to give 2-phenyl-4-methylenetetrahydrofuran (13a ,
0.21 g, 62%) and homoallylic alcohol, 2a (0.020 g, 7%).
2-phenyl-4-methylenetetrahydrofuran 13a : colorless oil; bp
120-125 °C/10 mmHg. 1H NMR (CDCl3) δ 2.57 (m, 1H, CHH),
2.95 (m, 1H, CHH), 4.41 (br d, 1H, J ) 13 Hz, OCHH), 4.58
Other reactions were carried out in a similar manner.
2-(4-Tolyl)-4-methylenetetrahydrofuran (13b): colorless oil;
bp 120-125 °C/8 mmHg. 1H NMR (CDCl3) δ 2.33 (Τïl-Me),
2.56 (m, 1H, CHH), 2.92 (m, 1H, CHH), 4.39 (br d, 1H, J ) 13
Hz, OCHH), 4.56 (br d, 1H, J ) 13 Hz, OCHH), 4.92 (m, 1H,
PhCH), 4.95 (m, 1H, dCH), 5.02 (m, 1H, dCH), 7.15 (d, 2H, J
) 8 Hz, p-Tol), 7.25 (d, 2H, J ) 8 Hz, p-Tol). 13C NMR (CDCl3)
δ 21.24 (Me), 41.21 (CH2), 71.28 (OCH2), 81.01 (ArCH), 104.14
(dC), 125.73, 128.88, 137.03, 138.57, 147.89 (dCH2). Found:
C, 82.51; H, 7.93. Calcd for C12H14O: C, 82.72; H, 8.10.
2-(4-Methoxyphenyl)-4-methylenetetrahydrofuran (13c): color-
1
less oil; bp 130-135 °C/8 mmHg. H NMR (CDCl3) δ 2.57 (m,
1H, CHH), 2.90 (m, 1H, CHH), 3.79 (s, 3H, OMe), 4.37 (br d,
1H, J ) 13 Hz, OCHH), 4.55 (br d, 1H, J ) 13 Hz, OCHH),
4.90 (dd, 1H, J ) 6 and 8 Hz, ArCH), 4.95 (m, 1H, dCH), 5.02
(m, 1H, dCH), 6.87 (m, 2H, Ar), 7.28 (m, 2H, Ar). 13C NMR
(CDCl3) δ 41.12 (CH2), 55.33 (OMe), 71.21 (OCH2), 80.85
(ArCH), 113.62, 127.12, 133.56, 147.94 (dCH2), 158.89 (Ar).
Found: C, 75.97; H, 7.78. Calcd for C12H14O2: C, 75.76; H,
7.42.
2-(4-Chlorophenyl)-4-methylenetetrahydrofuran (13d): color-
1
less oil; bp 120-125 °C/8 mmHg. H NMR (CDCl3) δ 2.51 (m,
1H, CHH), 2.93 (m, 1H, CHH), 4.40 (br d, 1H, J ) 13 Hz,
OCHH), 4.56 (br d, 1H, J ) 13 Hz, OCHH), 4.93 (dd, 1H, J )
6 and 8 Hz, ArCH), 4.96 (m, 1H, dCH), 5.03 (m, 1H, dCH),
7.26-7.33 (m, 4H, Ar). 13C NMR (CDCl3) δ 41.26 (CH2), 71.36
(OCH2), 80.36 (PhCH), 104.61 (dCH2), 127.09, 128.36, 133.04,
140.16 (Ar), 147.20 (dC). Found: C, 67.54; H, 5.71. Calcd for
C
11H11ClO: C, 67.87; H, 5.70.
2-(3,4-Dimethoxylphenyl)-4-methylenetetrahydrofuran
(13e): colorless oil (bp 130-140 °C/6 mmHg): 1H NMR (CDCl3)
δ 2.57 (m, 1H, CHH), 2.93 (m, 1H, CHH), 3.87 (s, 3H, MeO),
3.89 (s, 3H, MeO), 4.38 (br d, 1H, J ) 13 Hz, OCHH), 4.57 (br
d, 1H, J ) 13 Hz, OCHH), 4.90 (dd, 1H, J ) 6 and 8 Hz,
PhCH), 4.95 (m, 1H, dCH), 5.03 (m, 1H, dCH), 6.83 (d, 1H, J
) 8 Hz, meta-H), 6.89 (br d, 1H, J ) 8 Hz, ortho-H), 6.93 (br
s, 1H, ortho-H). 13C NMR (CDCl3) δ 55.84 (OMe), 55.94 (OMe),
71.28 (OCH2), 81.03 (ArCH), 104.23 (dCH2), 109.05, 110.83,
118.20, 134.05, 147.82 (dCH2), 148.33, 148.84. Found: C,
70.46; H, 7.20. Calcd for C13H16O3: C, 70.89; H, 7.32. When
the present reaction was carried out in refluxing benzene,
2-phenyl-4-methylenetetrahydrofuran (13a ) was obtained in
25% yield.
Rea ction of 3,3-Dip h en yl-3-h yd r oxyp r op yltr ip h en yl-
p h osp h on iu m Br om id e (12f) w ith Bu tyllith iu m F ol-
low ed by th e Ad d ition of P a r a for m a ld eh yd e. To a sus-
pension of 12f (1.11 g, 2 mmol) in THF was added butyllithium
THF solution (1.6 M, 2.8 mL, 4.4 mmol) at -20 °C, and the
mixture was stirred for 30 min. The resulting red solution was
warmed to 40 °C, and paraformaldehyde (0.30 g, 10 mmol) was
added in one portion. After refluxing for 1 h, the reaction
mixture was washed with water, dried over magnesium
sulfate, and finally evaporated to afford a colorless oil. This
oil was extracted with hexane to separate triphenylphosphine
oxide. The hexane extract was evaporated and chromato-
graphed over silica gel by hexane-dichloromethane to give 1,1-
diphenyl-3-buten-1-ol (2b, 0.38 g, 85%): colorless oil. 1H NMR
(CDCl3) δ 3.07 (d, 2H, J ) 7 Hz, CH2), 5.16 (d, 1H, J ) 10 Hz,
cis dCH), 5.22 (d, 1H, J ) 17 Hz, trans dCH), 5.67 (m, 1H,
dCH), 7.20 (m, 2H, para-H), 7.30 (m, 4H, meta-H), 7.44 (m,
4H, ortho-H). HRMS calcd for C16H16O: M+ 160.0888. Found:
M+ 160.0891.
Rea ction of 13a w ith P h en yl Tr ifla te in th e P r esen ce
of Tetr a k is(tr ip h en ylp h osp h in e) P a lla d iu m . To a solution
of 13a (0.16 g, 1 mmol) and diisopropylethylamine (0.26 g, 2
mmol) in benzene (15 mL) was added tetrakis(triphenylphos-
phine) palladium (0.037 g, 0.03 mmol) in one portion. After
(15) J adhav, P. K.; Bhat, K. S.; Perumal, P. T.; Brown, H. C. J . Org.
Chem. 1986, 51, 432.
J . Org. Chem, Vol. 67, No. 21, 2002 7359