W.M. Sherrill et al. / Tetrahedron 64 (2008) 8610–8617
8615
3.2.3. Compound 7l
100.61 MHz)
d
142.7, 137.2, 130.6 (þ), 128.9 (þ), 126.9 (þ), 126.0 (þ),
1H NMR (CDCl3, 400.13 MHz)
d
7.32 (td, J¼7.8, 1.8 Hz, 1H), 7.09
30.8 (þ), 26.1, 23.3 (þ), 23.2 (ꢂ), 19.3 (þ); HRMS (TOF-ES) found
(dd, J¼7.6, 1.8 Hz, 1H), 6.97 (d, J¼8.3 Hz, 1H), 6.95 (ps.-t, J¼8.3,
7.6 Hz, 1H), 3.99 (s, 3H), 2.05 (d, J¼7.6 Hz, 1H), 1.77 (d, J¼7.6 Hz, 1H),
208.9958, calcd for C10H10Br (MꢂMe) 208.9966 (3.8 ppm).
1.69 (s, 3H); 13C NMR (CDCl3, 100.61 MHz)
d
158.1, 131.2, 128.9 (þ),
3.3.5. Compound 8e
128.6 (þ),120.4 (þ),110.8 (þ), 55.6 (þ), 37.5, 34.1 (ꢂ), 34.0, 24.6 (þ);
HRMS (TOF-ES) found 239.0072, calcd for C11H12BrO (MꢂBr)
239.0072 (0.0 ppm).
1H NMR (CDCl3, 400.13 MHz)
d
major: 7.41 (d, J¼8.3 Hz, 2H), 7.26
(d, J¼8.3 Hz, 2H), 3.30 (dd, J¼7.8, 4.8 Hz, 1H), 1.73 (dd, J¼7.8, 6.3 Hz,
1H), 1.42 (s, 3H), 1.40 (s, 9H), 1.14 (dd, J¼6.3, 4.8 Hz, 1H); minor 7.45
(d, J¼8.3 Hz, 2H), 7.34 (d, J¼8.3 Hz, 2H), 3.16 (dd, J¼7.3, 4.3 Hz, 1H),
1.70 (s, 3H), 1.47–1.43 (m, 2H), 1.42 (s, 9H); 13C NMR (CDCl3,
3.3. Partial reduction of dibromocyclopropanes, typical
procedure
100.61 MHz)
d
major: 149.3, 141.3, 126.5 (þ, 2C), 125.4 (þ, 2C), 34.4,
31.3 (þ, 3C), 30.7 (þ), 25.1, 23.8 (þ), 23.4 (ꢂ); minor: 149.4, 139.0,
128.9 (þ, 2C),125.0 (þ, 2C), 34.4, 31.4 (þ, 3C), 28.5 (þ), 27.1, 27.0 (þ),
22.1 (ꢂ); HRMS (TOF-ES) found 187.1491, calcd for C14H19 (MꢂBr)
187.1487 (2.1 ppm).
3.3.1. Compound 8f
To
17.4 mmol) and titanium (IV) isopropoxide (10 mol %, 1.7 mmol,
490 L) in anhydrous diethyl ether (50 mL) was added dropwise
a stirred solution of dibromocyclopropane 7f (5.63 g,
m
3 M solution of ethylmagnesium bromide (21 mmol, 7.0 mL). When
intensive gas evolution had ceased, the mixture was stirred at room
temperature for 2 h, then cooled in an ice bath and quenched by
consecutive addition of water (10 mL) and 10% aqueous sulfuric
acid (20 mL). Organic phase was separated and aqueous layer was
extracted with ether (3ꢁ25 mL). Combined ethereal phases were
washed consecutively with 10% aqueous NaHCO3 and brine, dried
with MgSO4, filtered, and concentrated in vacuum. The residue was
purified by flash column chromatography on silica gel (eluent–
hexane) to afford bromocyclopropane 8f as colorless oil (mixture of
two diastereomers 1.8:1).39 Yield 3.08 g (12.5 mmol, 72%). 1H NMR
3.3.6. Compound 8g
1H NMR (CDCl3, 400.13 MHz)
d major: 7.40–7.37 (m, 1H), 7.34–
7.31 (m, 1H), 7.26–7.18 (m, 2H), 3.28 (dd, J¼8.3, 4.9 Hz, 1H), 1.61
(dd, J¼8.3, 6.2 Hz, 1H), 1.59 (s, 3H), 1.16 (dd, J¼6.2, 4.9 Hz, 1H); 13C
NMR (CDCl3, 100.61 MHz)
d
major: 141.9, 135.0, 130.5 (þ), 129.9
(þ), 128.2 (þ), 126.9 (þ), 30.3 (þ), 26.1, 23.4 (ꢂ), 22.6 (þ); HRMS
(TOF-ES) found 165.0478, calcd for C10H10Cl (MꢂBr) 165.0471
(4.2 ppm).
3.3.7. Compound 8h
1H NMR (CDCl3, 400.13 MHz)
d
major: 7.59 (d, J¼8.2 Hz, 2H), 7.39
(CDCl3, 400.13 MHz)
d
major: 7.29 (d, J¼8.3 Hz, 2H), 7.21 (d,
(d, J¼8.2 Hz, 2H), 3.24 (dd, J¼8.1, 4.8 Hz, 1H), 1.71 (dd, J¼8.1, 6.6 Hz,
1H), 1.66 (s, 3H), 1.17 (dd, J¼6.6, 4.8 Hz, 1H); minor: 7.64 (d,
J¼8.0 Hz, 2H), 7.47 (d, J¼8.0 Hz, 2H), 3.14 (dd, J¼7.5, 4.4 Hz, 1H), 1.50
J¼8.3 Hz, 2H), 3.20 (dd, J¼8.0, 4.8 Hz, 1H), 1.64 (ps.-t, J¼8.0, 7.2 Hz,
1H), 1.62 (s, 3H), 3.20 (dd, J¼7.2, 4.8 Hz, 1H); minor: 7.35 (d,
J¼8.3 Hz, 2H), 7.28 (d, J¼8.3 Hz, 2H), 3.11 (dd, J¼7.4, 4.5 Hz,1H), 1.46
(s, 3H), 1.47 (dd, J¼7.5, 6.6 Hz, 1H), 1.43 (dd, J¼6.6, 4.4 Hz, 1H); 13C
(s, 3H), 1.41 (ps.-t, J¼7.4, 6.8 Hz, 1H), 1.37 (dd, J¼6.8, 4.5 Hz, 1H); 13
C
NMR (CDCl3, 100.67 MHz)
d
major: 148.4, 128.8 (q, JCF¼32.9 Hz),
2
NMR (CDCl3, 100.61 MHz)
d
major: 142.9, 132.2, 128.6 (þ, 2C), 128.4
127.4 (þ, 2C), 125.5 (q, 3JCF¼3.7 Hz, þ, 2C), 124.1 (q, 1JCF¼272.3 Hz),
30.0 (þ), 25.6, 23.54 (þ), 23.49 (ꢂ); minor: 146.2, 129.8 (þ, 2C),
(þ, 2C), 30.1 (þ), 25.3, 23.8 (þ), 23.3 (ꢂ); minor: 140.7, 132.5, 130.7
(þ, 2C), 128.3 (þ, 2C), 27.9 (þ), 27.0, 26.8 (þ), 22.2; GC/MS (EI 70 eV)
major: 10.80 min, m/z 246 (Mþ, <1%), 165 (MꢂBr, 100%); minor:
10.65 min, m/z 246 (Mþ, <1%), 165 (MꢂBr, 100%), HRMS (TOF-ES)
found 165.0047, calcd for C10H10Cl (MꢂBr) 165.0470 (0.6 ppm).
2
3
129.0 (q, JCF¼32.9 Hz), 125.2 (q, JCF¼3.7 Hz, þ, 2C), 124.1 (q,
1JCF¼271.5 Hz), 27.5 (þ), 26.6 (þ), 25.6, 22.3 (ꢂ); 19F NMR (CDCl3,
376.50 MHz)
d
major: ꢂ62.44; minor: ꢂ62.37; GC/MS: major
(tR¼9.40 min) 278 (Mþ, <1%), 259 (MþꢂF, 1%), 209 (MþꢂCF3, 1%),
199 (MþꢂBr, 100%); minor (tR¼9.22 min) 278 (Mþ, <1%), 259
(MþꢂF, 1%), 209 (MþꢂCF3, 1%), 199 (MþꢂBr, 100%). HRMS (TOF-ES)
found 199.0734, calcd for C11H10F3 (MꢂBr) 199.0735 (0.5 ppm).
3.3.2. Compound 8b
1H NMR (CDCl3, 400.13 MHz)
d
major: 7.17 (d, J¼8.3 Hz, 2H), 7.14
(d, J¼8.3 Hz, 2H), 3.23 (dd, J¼7.8, 4.3 Hz, 1H), 2.35 (s, 3H), 1.65 (ps.-t,
J¼7.8, 6.5 Hz,1H),1.62 (s, 3H),1.07(dd, J¼6.5, 4.6 Hz,1H); minor: 7.25
(d, J¼8.1 Hz, 2H), 7.20 (d, J¼8.1 Hz, 2H), 3.11 (dd, J¼7.2, 4.6 Hz, 1H),
2.38 (s, 3H), 1.47 (s, 3H), 1.40–1.37 (m, 2H); 13C NMR (CDCl3,
3.3.8. Compound 8i
1H NMR (CDCl3, 400.13 MHz)
d
8.24 (d, J¼8.3 Hz, 1H), 7.91 (d,
J¼8.1 Hz, 1H), 7.79 (dd, J¼6.3, 3.3 Hz, 1H), 7.63 (td, J¼8.3, 1.7 Hz, 1H),
7.55 (td, J¼8.1, 1.0 Hz, 1H), 7.46–7.43 (m, 2H), 3.39 (d, J¼8.1, 4.5 Hz,
1H), 1.75 (s, 3H), 1.76 (m, 1H), 1.28 (dd, J¼6.3, 4.5 Hz, 1H); 13C NMR
100.61 MHz)
d
major 141.5, 136.1, 129.2 (þ, 2C), 126.9 (þ, 2C), 30.6
(þ), 25.4, 24.0 (þ), 23.2 (ꢂ), 21.0 (þ); minor 139.2, 136.3, 129.2 (þ,
2C), 128.9 (þ, 2C), 28.4 (þ), 27.2, 27.0 (þ), 22.1 (ꢂ), 21.1 (þ); HRMS
(TOF-ES) found 223.0121, calcd for C11H12Br (MꢂH) 223.0122
(0.4 ppm).
(CDCl3, 100.61 MHz)
d
141.1, 134.0, 131.6, 128.8 (þ), 127.6 (þ), 126.3
(þ), 126.0 (þ), 125.7 (þ), 125.5 (þ), 124.8 (þ), 30.8 (þ), 25.6, 24.2
(þ), 23.1 (ꢂ); HRMS (TOF-ES) found 181.1014, calcd for C14H13
(MꢂBr) 181.1017 (1.7 ppm).
3.3.3. Compound 8c
1H NMR (CDCl3, 400.13 MHz)
d
major: 7.36–7.11 (m, 4H), 3.31
3.3.9. Compound 8j
(dd, J¼8.1, 4.8 Hz, 1H), 2.43 (s, 3H), 1.72 (ps.-t, J¼8.1, 6.3 Hz, 1H), 1.70
(s, 3H), 1.14 (dd, J¼6.3, 4.8 Hz, 1H); minor: 7.36–7.11 (m, 4H), 3.15
(dd, J¼7.6, 4.3 Hz, 1H), 2.47 (s, 3H), 1.53 (s, 3H), 1.48–1.41 (m, 2H);
1H NMR (CDCl3, 400.13 MHz)
d
major: 7.25 (dd, J¼8.6 Hz,
4JHF¼5.3 Hz, 2H), 7.02 (ps.-t, J¼3JHF¼8.6 Hz, 2H), 3.22 (dd, J¼7.8,
4.8 Hz, 1H), 1.64 (dd, J¼7.8, 6.3 Hz, 1H), 1.62 (s, 3H), 1.10 (dd, J¼6.3,
4.8 Hz, 1H); minor: 7.31 (dd, J¼8.8 Hz, 4JHF¼5.6 Hz, 2H), 7.07 (ps.-t,
J¼3JHF¼8.8 Hz, 2H), 3.11 (dd, J¼7.3, 4.3 Hz, 1H), 1.47 (s, 3H), 1.41 (dd,
13C NMR (CDCl3, 100.61 MHz)
d
major: 144.4, 138.1, 128.4 (þ), 127.8
(þ), 127.2 (þ), 124.0 (þ), 30.6 (þ), 27.0 (þ), 25.7, 24.0 (þ), 23.2 (ꢂ);
minor: 142.0, 137.6, 130.1 (þ), 128.0 (þ), 127.6 (þ), 126.4 (þ), 28.3
(þ), 27.5 (þ), 22.0 (ꢂ), 21.5, 21.4 (þ); HRMS (TOF-ES) found
223.0123, calcd for C11H12Br (MꢂH) 223.0122 (0.4 ppm).
J¼7.3, 6.8 Hz, 1H), 1.37 (dd, J¼6.8, 4.3 Hz, 1H); 13C NMR (CDCl3,
1
100.61 MHz)
d
major: 161.4 (d, JCF¼245.2 Hz), 140.2 (d,
4JCF¼2.9 Hz), 128.7 (d, 3JCF¼8.1 Hz, þ, 2C), 115.3 (d, 2JCF¼21.2 Hz, þ,
1
2C), 30.1 (þ), 25.3, 24.1 (þ), 23.2 (ꢂ); minor: 161.6 (d, JCF
¼
3.3.4. Compound 8d
245.2 Hz), 138.0 (d, 4JCF¼3.7 Hz), 130.9 (d, 3JCF¼8.1 Hz, þ, 2C), 115.0
1H NMR (CDCl3, 400.13 MHz)
d
7.24–7.21 (m, 1H), 7.18–7.14 (m,
(d, JCF¼21.2 Hz, þ, 2C), 28.1 (þ), 26.97 (þ), 26.94, 22.3 (ꢂ); HRMS
2
3H), 3.22 (dd, J¼8.1, 4.6 Hz,1H), 2.43 (s, 3H),1.57 (ps.-t, J¼8.1, 6.3 Hz,
(TOF-ES) found 149.0767, calcd for C10H10F (MꢂBr) 149.0767
1H), 1.52 (s, 3H), 1.09 (dd, J¼6.3, 4.6 Hz, 1H); 13C NMR (CDCl3,
(0.7 ppm).