4-Butylspiropentylcarbinyl Radicals
A R T I C L E S
solution was rapidly added at room temperature to initiate the reaction;
the ethereal solution became cloudy and the lithium metal became shiny,
and the rest of the material was added at -20 to -25 °C. After an
additional hour at -20 °C, the alkyllithium was transferred to an
addition funnel under a dry stream of argon and added over 1 h at
-50 to -60 °C to 5.1 g (20 mmol) of CuI in 10 mL of ether. After
stirring at -50 °C for 1 h, the brownish solution was warmed to -20
to -30 °C and 2.08 g (2.48 mmol) of 3,4-epoxy-3-methyl-1-butene
was added dropwise to it. The reaction mixture was stirred for 1.5 h at
-20 °C and quenched with saturated NH4Cl at -30 °C. Aqueous
ammonia (10%) was then added until a clear dark-blue solution resulted
and the aqueous material was extracted with ether (3 × 20 mL). The
combined organic material was washed with brine, dried over MgSO4,
and concentrated by distillation through a 20-cm Vigreux column at
atmospheric pressure. The residue was distilled under vacuum (bp 52-
53 °C at 0.1 Torr (lit. 57.7-59.0 °C under vacuum)30 to give 2.66 g
(84%) of a 77:23 mixture of 24a and 24b as a colorless oil. (24a): 1H
NMR (500 MHz, CDCl3) δ 0.90 (t, 3H, J ) 7.0 Hz), 1.28-1.36 (m,
4H), 1.55 (br. s, 1H), 1.66 (s, 3H), 2.03 (q, 2H, J ) 7.0), 3.99 (s, 2H),
5.41 (tq, 1H, J ) 7.5 and 1.5 Hz). 13C NMR (125 MHz, CDCl3) δ
13.8, 14.2, 22.6, 27.5, 31.9, 69.2, 126.8, 134.8. HRMS-EI calcd for
C8H16O (M+), 128.1201; found 128.1199. (24b): 1H NMR (500 MHz,
CDCl3) δ 0.90 (t, 3H, J ) 7.0 Hz), 1.28-1.36 (m, 4H), 1.45 (br s,
1H), 1.79 (q, 3H, J ) 1.5 Hz), 2.03 (q, 2H, J ) 7.0), 4.12 (s, 2H), 5.30
(tq, 1H, J ) 7.0 and 1.5 Hz). 13C NMR (125 MHz, CDCl3) δ 13.8,
14.1, 21.4, 22.5, 27.5, 32.4, 61.8, 129.0, 134.3.
(Z)-2-Butyl-1-methyl-1-vinylcyclopropane (20a) and (E)-2-Butyl-
1-methyl-1-vinyl-cyclopropane (20b). Under a dry stream of argon,
4.09 mL of a 1.0 M solution of NaHMDS in THF was added dropwise
to a stirred solution of 1.46 g (4.09 mmol) of methyltriphenyl-
phosphonium bromide in 18 mL of THF at 0 °C. The reaction mixture
was stirred for an additional 15 min at 0 °C. While maintaining the
solution at 0 °C, 0.190 g (1.36 mmol) of an isomeric mixture of 26a
and 26b in 2.5 mL of THF was added dropwise. Upon warming to
room temperature, the solution was stirred for an additional 3 h before
being cooled to 0 °C and quenched with 10 mL of cold water. The
resulting suspension was extracted with pentane (3 × 10 mL) and the
combined organic layers were washed with brine and dried over MgSO4.
Distillation through a 20-cm Vigreux column at atmospheric pressure
afforded a solid residue which was rinsed twice with 3-mL portions of
pentane. Column chromatography on silica gel with pentane afforded
0.110 g (59%) of 20a and 20b in a 78:22 ratio as a colorless volatile
liquid after removal of the solvent by distillation through a 20-cm
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Vigreux column at atmospheric pressure. (20a): H NMR (500 MHz,
CDCl3) δ 0.26 (m, 1H), 0.74 (m, 2H), 0.91 (t, 3H, J ) 7.0 Hz), 1.16
(s, 3H), 1.30-1.45 (m, 6H), 4.83 (dd, 1H, J ) 1.5 and 11.0 Hz), 4.91
(dd, 1H, J ) 1.5 and 17.0 Hz), 5.41 (dd, 1H, J ) 5.0 and 17.0 Hz).
13C NMR (125 MHz, CDCl3) δ 14.4, 15.6, 21.3, 22.1, 22.8, 26.4, 29.2,
32.4, 108.5, 148.4. HRMS-CI (NH3) calcd for C10H19 (M + H)+,
139.1488; found 139.1481, calcd for C10H22N (M + NH4)+, 156.1754;
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found 156.1757. (20b): H NMR (500 MHz, CDCl3) δ 0.40 (t, 1H, J
) 5.0 Hz), 0.69 (dd, 1H, J ) 4.0 and 8.5 Hz), 0.77 (t, 1H, J ) 7.0
Hz), 0.90 (t, 3H, J ) 7.0 Hz), 1.18 (s, 3H), 1.20-1.40 (m, 6H), 4.99
(s, 1H), 5.02 (dd, 1H, J ) 2.0 and 7.5 Hz), 5.69 dd (1H, J ) 11.0 and
17.0 Hz). 13C NMR (75 MHz, CDCl3) δ 14.4, 21.4, 22.5, 22.7, 23.2,
28.0, 29.5, 32.2, 111.8, 142.9. HRMS-CI (NH3) calcd for C10H19 (M
+ H)+, 139.1488; found 139.1487, calcd for C10H22N (M + NH4)+,
156.1754; found 156.1751.
(Z)-(2-Butyl-1-methylcyclopropyl)methanol (25a) and (E)-(2-
Butyl-1-methylcyclo-propyl)methanol (25b). By reacting 0.512 g (4
mmol) of an isomeric mixture of (E)-2-methylhept-2-en-1-ol (24a) and
(Z)-2-methylhept-2-en-1-ol (24b) with 0.64 mL (8 mmol) of CH2I2,
4.0 mL (4 mmol) of a 1.0 M solution of Et2Zn in hexane, and 0.6 mL
of a 1.0 M solution of TiCl4 (0.6 mmol) in CH2Cl2 as described for the
synthesis of 13b, 0.482 g (85%) of 25a and 25b was obtained in a
trans-1-Bromo-2-butylcyclopropane (28). Following literature
procedures,11 4.11 g (50 mmol) of 1-hexyne was converted to 4.02 g
(36%) of 28 containing 5% of the cis isomer as determined by GC-
MS. 1H NMR (300 MHz, CDCl3) δ 0.76 (dt, 1H, J ) 6.0 and 7.0 Hz),
0.91 (t, 3H, J ) 7.0 Hz), 0.98 (m,1H), 1.21 (m, 1H), 1.22-1.42 (m,
6H), 2.60 (m, 1H). 13C NMR (75 MHz, CDCl3) δ 14.3, 16.1, 20.3,
22.6, 23.1, 31.1, 32.7. HRMS-CI (4% NH3 in CH4) calcd for C7H13Br
(M)+, 176.0201 and 178.0181; found 176.0192 and 178.0179.
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78:22 ratio. (25a): H NMR (500 MHz, CDCl3) δ -0.04 (t, 1H, J )
5.0 Hz), 0.51 (dd, 1H, J ) 4.0 and 8.5 Hz), 0.58 (m, 1H), 0.89 (t, 3H,
J ) 7.0 Hz), 1.12 (s, 3H), 1.32-1.36 (m, 6H), 1.61 (br s, 1H), 3.31 (s,
2H). 13C NMR (125 MHz, CDCl3) δ 14.3, 15.4, 16.9, 22.1, 22.3, 22.8,
29.0, 32.6, 72.8. HRMS-CI (NH3) calcd for C9H17 (M - OH)+,
125.1330; found 125,1328, calcd for C9H20N (M - H2O + NH4)+,
142.1596; found 142.1594, calcd for C9H22NO (M + NH4)+, 160.1701;
found 160.1689. (25b): 1H NMR (500 MHz, CDCl3): δ 0.10 (t, 1H,
J ) 5.0 Hz), 0.45 (dd, 1H, J ) 4.5 and 8.5 Hz), 0.65 (m, 1H), 0.89 (t,
1H, J ) 7.0 Hz), 1.13 (s, 3H), 1.20-1.42 (m, 6H), 1.45 (br s, 1H),
3.51 (d, 1H, J ) 11.0 Hz), 3.58 (d, 1H, J ) 11.0 Hz). 13C NMR (125
MHz, CDCl3) δ 14.3, 17.9, 22.4, 22.8, 22.9, 25.3, 29.2, 32.7, 67.7.
HRMS-CI (NH3) calcd for C9H22NO (M + NH4)+, 160.1701; found
160.1698, calcd for C9H20N (M - H2O + NH4)+, 142.1596; found
142.1598.
cis-1-Allyl-2-butylcyclopropane (21a) and trans-1-allyl-2-butyl-
cyclopropane (21b). Following a literature procedure,31 0.885 g (5
mmol) of trans-1-bromo-2-butyl-cyclopropane (28) containing 5% of
the cis isomer was converted to 0.350 g (46%) of 21b containing 5%
of the cis isomer (21a) as determined by GC-MS. (21b): 1H NMR
(500 MHz, CDCl3) δ 0.22 (m, 2H), 0.47 (m, 2H), 0.89 (t, 3H, J ) 7.0
Hz), 1.22-1.40 (m, 6H), 1.96 (m, 2H), 4.95-4.97 (m, 1H), 5.04-
5.08 (m, 1H), 5.84-5.92 (m, 1H). 13C NMR (125 MHz, CD2Cl2) δ
11.9, 14.5, 18.3, 19.0, 23.2, 32.4, 34.4, 38.8, 114.5, 139.0. HRMS-CI
(NH3) calcd for C10H17 (M - H)+, 137.1331; found 137.1328, calcd
for C10H22N (M + NH4)+, 156.1754; found 156.1751.
4-Methyloct-1-en-3-ol (30). A few crystals of iodine were added
to a solution of 5.2 g (0.21 mol) of magnesium turnings in 12 mL of
anhydrous ether, and this mixture was warmed for 2 min with a heat
gun under a dry argon atomosphere. 2-Bromohexane (16.5 g, 100 mmol)
in 90 mL of ether was subsequently added in small portions until the
reaction began, and then it was added dropwise so as to maintain a
gentle reflux. After the addition was complete, the reaction mixture
was heated for an additional 1 h and then acrolein (3.58 g, 64 mmol)
was slowly added. After stirring the reaction mixture at room temper-
ature for an additional 1 h, it was slowly poured into 70 mL of ice
water. The resulting precipitate was dissolved by slowly adding a
solution of 4.1 mL of concentrated sulfuric acid in 14 mL of water.
(Z)-(2-Butyl-1-methyl-1-cyclopropane)carboxaldehyde (26a) and
(E)-(2-Butyl-1-methyl-1-cyclopropane)carboxaldehyde (26b). By
reacting 0.379 g (2.67 mmol) of an isomeric mixture of 25a and 25b
with 0.406 g (3.46 mmol) of N-MMO, 0.07 g of TPAP, and 0.15 g of
crushed 4 Å molecular sieves as described for the synthesis of aldehyde
15b, 0.360 g (96%) of 26a and 26b was obtained in a 78:22 ratio as a
1
colorless volatile liquid. (26a): H NMR (300 MHz, CDCl3) δ 0.64
(m, 1H), 0.90 (t, 3H, J ) 7.0 Hz), 1.23 (s, 3H), 1.30-1.46 (m, 8H),
8.62 (s, 1H). 13C NMR (125 MHz, CDCl3) δ 11.2, 14.2, 20.2, 22.6,
25.2, 28.1, 31.9, 32.1, 203.1. HRMS-CI (NH3) calcd for C9H17O (M +
H)+, 141.1280; found 141.1271, calcd for C9H20NO (M + NH4)+,
158.1545; found 158.1540. (26b): 1H NMR (500 MHz, CDCl3) δ 0.89
(t, 3H, J ) 7.0 Hz), 1.11 dd, 1H, J ) 4.5 and 7.5 Hz), 1.23 (s, 3H),
1.24-1.36 (m, 5H), 1.39 (m, 1H), 1.55 (m, 1H), 1.63 (m, 1H), 9.14 (s,
1H). 13C NMR (125 MHz, CDCl3) δ 14.2, 18.3, 22.5, 22.8, 28.7, 32.1,
32.26, 32.33, 203.6. HRMS-CI (NH3) calcd for C9H17O (M + H)+,
141.1280; found 141.1283, calcd for C9H20NO (M + NH4)+, 158.1545;
found 158.1543.
(31) Hiyama, T.; Yamamoto, H.; Nishio, K.; Kitatani, K.; Nozaki, H. Bull. Soc.
Chim. Jpn. 1979, 52, 3632.
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J. AM. CHEM. SOC. VOL. 124, NO. 7, 2002 1285