mixture was extracted with ether (10 mL × 3). The combined
organic layer was dried over MgSO4 and concentrated. The
product was determined from 1H NMR spectroscopy. Purification
was performed by silica gel column chromatography eluting with
hexane. Further purification was performed by distillation under
reduced pressure.
(CDCl3, 400 MHz) d 5.85 (ddd, J = 17.1, 10.3 and 8.5 Hz, 1H),
5.08 (dd, J = 10.3 and 1.9 Hz, 1H), 5.04 (dd, J = 17.1 and 1.9 Hz,
1H), 2.51 (dd, J = 14.0 and 7.2 Hz, 1H), 2.08 (dd, J = 13.8 and
8.2 Hz, 1H), 1.24 (t, J = 7.0 Hz, 3H), 1.21 (t, J = 7.0 Hz, 3H);
13C NMR (CDCl3, 100 MHz) d 172.77, 172.69, 141.16, 138.10,
128.87, 128.22, 125.75, 115.84, 61.45, 61.42, 58.75, 46.57, 44.81,
38.80, 38.24, 36.30, 14.02, 13.97; MS (EI, 70 eV) m/z 330 (M+,
22), 256 (59), 239 (49), 229 (24), 184 (23), 183 (37), 182 (30),
173 (46), 165 (65), 143 (56), 91 (CH2Ph, 100); HRMS calcd for
C20H26O4: 330.1831, found: m/z 330.1820 (EI, (M+), −1.1 mmu).
((E)-1,1-Dimethyl-but-2-enyl)benzene, 6d-E. IR (neat) 1597
−1
1
=
(C C) cm ; H NMR (CDCl3, 400 MHz) d 7.35 (d, J = 8.0 Hz,
2H), 7.29 (dd, J = 8.0 and 7.5 Hz, 2H), 7.17 (t, J = 7.5 Hz,
1H), 5.64 (dq, J = 15.5 and 1.4 Hz, 1H), 5.45 (dq, J = 15.5 and
6.3 Hz, 1H), 1.71 (dd, J = 6.3 and 1.4 Hz, 3H), 1.38 (s, 6H); 13
C
3-Benzyl-4-vinyltetrahydrofuran, 9b. >99%; (major, 9b-trans)
NMR (CDCl3, 100 MHz) d 149.40, 141.08, 127.97, 126.11, 125.57,
120.95, 40.27, 28.86, 18.03; MS (EI, 70 eV) m/z 160 (M+, 39), 145
(M+ − CH3, 100), 117 (22); HRMS calcd for C12H16: 160.1252,
found: m/z 160.1257 (EI, (M+), +0.5 mmu).
the stereochemistry of the products was determined from NOE
−1
=
observations. See ESI†. IR (neat) 1639 (C C) cm , 1053 (C–O–
C) cm−1; H NMR (CDCl3, 400 MHz) d 7.27 (dd, J = 7.5 and
1
7.4 Hz, 2H), 7.19 (t, J = 7.4 Hz, 1H), 7.14 (d, J = 7.5, 2H), 5.69
(ddd, J = 17.1 and 10.1 and 8.5 Hz, 1H), 5.08 (dd, J = 17.1 and
1.7 Hz, 1H), 5.05 (dd, J = 10.1 and 1.7 Hz, 1H), 4.03 (dd, J =
8.2 and 8.2 Hz, 1H), 3.88 (dd, J = 8.5 and 7.5 Hz, 1H), 3.54
(dd, J = 8.2 and 8.7 Hz, 1H), 3.53 (dd, J = 8.5 and 7.9 Hz, 1H),
2.91 (dd, J = 13.8 and 4.8 Hz, 1H), 2.58–2.48 (m, 2H), 2.31–2.22
(m, 1H); 13C NMR (CDCl3, 100 MHz) d 140.28, 137.85, 128.62,
128.38, 126.09, 116.46, 73.35, 72.85, 50.32, 47.24, 37.75; MS (EI,
70 eV) m/z 188 (M+, 1), 157 (27), 129 (30), 104 (32), 92 (51), 91
(PhCH2, 100); HRMS calcd for C13H16O: 188.1201, found: m/z
188.1210 (EI, (M+), +0.9 mmu); anal. calcd for C13H16O: C, 82.94;
H, 8.57, found: C, 82.92; H, 8.31%; (minor, 9b-cis) This compound
was a minor product and was not isolated as a pure compound.
The identifiable signals in the crude mixture after GPC are given
((Z)-1,1-Dimethyl-but-2-enyl)benzene, 6d-Z. IR (neat) 1601
−1
1
=
(C C) cm ; H NMR (CDCl3, 400 MHz) d 7.39 (d, J = 8.0 Hz,
2H), 7.28 (dd, J = 8.0 and 7.2 Hz, 2H), 7.16 (t, J = 7.2 Hz,
1H), 5.69 (dq, J = 11.4 and 1.7 Hz, 1H), 5.41 (dq, J = 11.4 and
7.2 Hz, 1H), 1.43 (s, 6H), 1.20 (dd, J = 7.2 and 1.7 Hz, 3H); 13
C
NMR (CDCl3, 100 MHz) d 150.42, 140.56, 127.99, 126.11, 125.26,
124.77, 39.92, 31.12, 14.19; MS (EI, 70 eV) m/z 160 (M+, 36), 145
(M+ − CH3, 100), 117 (23); HRMS calcd for C12H16: 160.1252,
found: m/z 160.1250 (EI, (M+), −0.2 mmu).
Typical procedure for radical cyclization of allenenes 8 using
HInCl2 (InCl2OMe–PhSiH3 system, Table 2)
A 30 mL round bottom flask charged with InCl3 (0.442 g,
2.0 mmol) and NaOMe (0.108 g, 2.0 mmol) was dried by heating
at 110 ◦C under reduced pressure for 1 h. After the flask was filled
with nitrogen, THF (10 mL) was added to dissolve the InCl3.
The resulting mixture was stirred at rt for 0.5 h. Then PhSiH3
(0.260 g, 2.4 mmol), allenene 8 (1.0 mmol) and Et3B (0.1 mL,
1M solution in hexane, 0.1 mmol) were added successively, and
the resulting solution was stirred at rt for 20 h. After 1M HCl
aq was added, the reaction mixture was extracted with ether
(10 mL × 3). The combined organic layer was dried over MgSO4
and concentrated. The cyclized product was determined from
1H NMR spectroscopy. Purification was performed by silica gel
column chromatography eluting with hexane. Further purification
was performed by distillation under reduced pressure.
1
here. H NMR (CDCl3, 400 MHz) d 5.89 (ddd, J = 17.1, 10.3
and 9.4 Hz, 1H), 3.96 (dd, J = 8.5 and 6.5 Hz, 1H), 3.81 (dd,
J = 8.6 and 7.2 Hz, 1H), 3.74 (dd, J = 8.5 and 4.8 Hz, 1H), 2.78
(dd, J = 13.5 and 5.3 Hz, 1H); 13C NMR (CDCl3, 100 MHz) d
140.78, 136.13, 128.75, 128.49, 125.97, 116.88, 72.67, 71.93, 46.74,
44.82, 34.25; MS (EI, 70 eV) m/z 188 (M+, 2), 157 (27), 105 (25),
104 (29), 92 (47), 91 (CH2Ph, 100); HRMS calcd for C13H16O:
188.1201, found: m/z 188.1198 (EI, (M+), −0.3 mmu).
3-(4-Chlorophenylmethyl)-4-vinyltetrahydrofuran, 9c. >99%;
the stereochemistry of the products was determined from com-
1
parison of H NMR spectrum with 9b. These compounds were
not isolated as pure compounds and were obtained as a mixture
of diastereomers (9c-trans : 9c-cis = 83 : 17). The observed data
−1
−1
=
Diethyl 3-benzyl-4-vinylcyclopentane-1,1-dicarboxylate, 9a.
are given here. IR (neat) 1639 (C C) cm , 1095 (C–O–C) cm ,
1053 (C–O–C) cm−1; anal. calcd for C13H15ClO: C, 70.11; H, 6.79;
Cl, 15.92, found: C, 69.84; H, 6.58; Cl, 16.20%; (major, 9c-trans)
1H NMR (CDCl3, 400 MHz) d 7.24 (d, J = 8.2 Hz, 2H), 7.07 (d,
J = 8.2 Hz, 2H), 5.67 (ddd, J = 17.0, 10.1 and 8.5 Hz, 1H), 5.07
(dd, J = 17.0 and 1.7 Hz, 1H), 5.05 (dd, J = 10.1 and 1.7 Hz, 1H),
4.02 (dd, J = 8.5 and 8.2 Hz, 1H), 3.86 (dd, J = 8.5 and 7.5 Hz,
1H), 3.54 (dd, J = 8.5 and 8.5 Hz, 1H), 3.49 (dd, J = 8.5 and
8.2 Hz, 1H), 2.87 (dd, J = 13.8 and 5.1 Hz, 1H), 2.56–2.46 (m,
2H), 2.28–2.18 (m, 1H); 13C NMR (CDCl3, 100 MHz) d 138.69,
137.69, 131.87, 129.95, 128.50, 116.60, 73.17, 72.85, 50.26, 47.13,
37.13; MS (EI, 70 eV) m/z 222 (M+, 9), 138 (27), 125 (CH2C6H4Cl,
100), 91 (22); HRMS calcd for C13H15ClO: 222.0811, found: m/z
222.0808 (EI, (M+), −0.3 mmu); (minor, 9c-cis) 1H NMR (CDCl3,
400 MHz) d 5.86 (ddd, J = 17.0, 10.1 and 9.2 Hz, 1H), 5.16 (dd, J =
10.1 and 1.7 Hz, 1H), 5.10 (dd, J = 17.0 and 1.7 Hz, 1H), 3.96 (dd,
−1
81%; (major) IR (neat) 1732 (C O) cm ; 1H NMR (CDCl3,
=
400 MHz) d 7.30–7.14 (m, 5H), 5.69 (ddd, J = 17.1, 10.2 and
8.2 Hz, 1H), 5.09 (dd, J = 17.1 and 1.9 Hz, 1H), 5.05 (dd, J =
10.2 and 1.9 Hz, 1H), 4.22–4.09 (m, 4H), 2.92 (dd, J = 13.5 and
3.6 Hz, 1H), 2.50 (dd, J = 13.5 and 7.5 Hz, 1H), 2.36–2.21 (m,
3H), 2.05 (dd, J = 13.5 and 10.9 Hz, 1H), 2.00–1.87 (m, 2H), 1.23
(t, J = 7.0 Hz, 3H), 1.19 (t, J = 7.0 Hz, 3H); 13C NMR (CDCl3,
100 MHz) d 172.63, 172.47, 140.74, 139.96, 128.81, 128.24,
125.83, 115.83, 61.41, 61.36, 58.21, 50.04, 46.71, 40.30, 39.56,
39.17, 14.00, 13.96; MS (EI, 70 eV) m/z 330 (M+, 28), 256 (52),
239 (36), 211 (26), 183 (33), 182 (20), 173 (36), 165 (63), 143 (79),
91 (CH2Ph, 100); HRMS calcd for C20H26O4: 330.1831, found:
m/z 330.1813 (EI, (M+), −1.8 mmu); (minor) This compound
was a minor product and was not purely isolated. The identifiable
1
signals in the crude mixture after GPC are given here. H NMR
1952 | Org. Biomol. Chem., 2008, 6, 1949–1954
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