Y.R. Bhorge et al. / Tetrahedron 68 (2012) 4846e4851
4849
37.9, 39.2, 39.6, 92.8, 152.5; high-resolution MS m/e calcd for
C11H15Br 226.0357, found 226.0355.
crude product derived from 1 mmol of 1h by flash chromatography
on silica gel (elution with hexane) afforded 165 mg (74%) of 2h as
a colorless oil:Rf¼0.80 (Hexane) : 1H NMR (CDCl3, 400 MHz)
4.3.3. 1-tert-Butyl-4-(bromomethylene)cyclohexane 2c.16 As de-
scribed above in method A, purification of the crude product de-
rived from 1 mmol of 1c by flash chromatography on silica gel
(elution with hexane) afforded 173 mg (75%) of 2c as a colorless oil:
Rf¼0.89 (Hexane): IR (neat) 2954, 2867, 1715, 1638, 1475, 1443,
d
1.82e1.86 (m, 2H), 2.61e2.64 (m, 2H), 2.74 (t, J¼6.0 Hz, 2H), 6.71
(t, J¼2.0 Hz, 1H), 7.10e7.19 (m, 3H), 7.45 (d, J¼6.4 Hz, 1H); 13C NMR
(CDCl3, 100 MHz)
d 22.5, 29.8, 30.4, 103.5, 123.9, 126.3, 127.7, 128.8,
134.0, 137.7, 139.9; high-resolution MS m/e calcd for C11H11Br
222.0044, found 222.0035.
1366, 1283, 1240, 1011, 789, 701 cmꢂ1 1H NMR (CDCl3, 400 MHz)
;
d
0.84 (s, 9H), 0.97e1.07 (m, 2H), 1.12e1.18 (m, 1H), 1.69e1.77 (m,
4.3.9. ((E)-2-Bromovinyl)cyclohexane 2i.19 As described above in
method A, E/Z analysis (400-MHz 1H NMR integration of the vinyl
protons) of the crude adduct revealed the presence of a 90:10 ratio
of E and Z isomers. Purification of the crude product derived from
1 mmol of 1i by flash chromatography on silica gel (elution with
hexane) afforded 136 mg (72%) of 2i as a colorless oil: Rf¼0.82
(Hexane) : IR (neat) 2932, 2856, 1726, 1649, 1582, 1447, 1164, 1036,
1H), 1.83e1.91 (m, 2H), 1.98e2.01 (m, 1H), 2.36e2.40 (m, 1H),
2.89e2.93 (m, 1H), 5.80 (t, J¼1.6 Hz, 1H); 13C NMR (CDCl3, 100 MHz)
d
27.4, 27.5, 28.5, 31.0, 32.3, 35.4, 47.9, 97.2, 145.0; high-resolution
MS m/e calcd for C11H19Br 230.0670, found 230.0663.
4.3.4. (E)-2-(Bromomethylene)-1,1-dimethylcyclohexane 2d. As de-
scribed above in method A, E/Z analysis (400-MHz 1H NMR in-
tegration of the vinyl protons) of the crude adduct revealed the
presence of a >97:3 ratio of E and Z isomers. Purification of the
crude product derived from 1 mmol of 1d by flash chromatography
on silica gel (elution with hexane) afforded 113 mg (56%) of 2d as
a colorless oil: Rf¼0.90 (Hexane) : IR (neat) 2929, 2860, 1611, 1453,
993, 942 cmꢂ1 1H NMR (CDCl3, 400 MHz)
; d 1.0e1.25 (m, 5H),
1.60e1.71 (m, 5H), 1.99 (m, 1H), 5.98 (dd J¼0.8, 13.2 Hz, 1H), 6.14
(dd, J¼6.8, 13.2 Hz,1H); 13C NMR (CDCl3,100 MHz)
d 25.7, 25.8, 32.2,
41.7, 103.0, 143.7; high-resolution MS m/e calcd for C8H13Br
188.0201, found 188.0208.
1388, 1363, 1294, 1151, 984, 830, 781, 711 cmꢂ1
;
1H NMR (CDCl3,
4.3.10. 1-((E)-and 1-(Z)-4-Bromobut-3-enyl)benzene 2j.20 To a sus-
pension consisting of Mg (291 mg, 12 mmol), TiCl4 (3.0 mmol, 1 M
in ClCH2CH2Cl, 4 mL) and CHBr3 (0.08 mL), at 0 ꢀC was added
a solution of 3-phenylpropanal (134 mg, 1 mmol) in ClCH2CH2Cl
(1 mL) and THF (0.5 mL). The black slurry was stirred for 8 h at
0e25 ꢀC, then cooled to 0 ꢀC, and carefully poured into ice-cold
saturated potassium carbonate solution (10 mL). The resulting
mixture was stirred with 20 mL of ether and the phases were
separated. After this procedure was repeated twice, the combined
extracts were dried, evaporated. Diastereomer analysis (400-MHz
1H NMR integration of the vinyl protons) of the crude adduct
revealed the presence of a 58:42 ratio of E to Z isomers. Purification
by chromatography on silica gel (elution with hexane) afforded
a separable mixture of the E- and Z-vinyl bromides (122 mg, 58%
yield). E isomer as a colorless oil: IR (neat) 3063, 2326, 2926, 2855,
400 MHz)
d 1.05 (s, 6H), 1.33e1.36 (m, 2H), 1.49e1.57 (m, 3H), 2.39
(t, J¼6.4 Hz, 2H), 5.90 (s,1H); 13C NMR (CDCl3,100 MHz)
d 22.2, 27.0,
27.5, 28.2, 38.5, 41.5, 98.7, 151.5; high-resolution MS m/e calcd for
C9H15Br 202.0362, found 202.0362.
4.3.5. (E)-Methyl
2-(bromomethylene)-7,7-dimethylbicyclo[2.2.1]
heptane-1-carboxylate 2e. As described above in method A, E/Z
analysis (400-MHz 1H NMR integration of the vinyl protons) of the
crude adduct revealed the presence of a >97:3 ratio of E and Z iso-
mers. Purification of the crude product derived from 1 mmol of 1e by
flash chromatography on silica gel (elution with hexane) afforded
191 mg (70%) of 2e as a colorless oil: Rf¼0.29 (Hexane): IR (neat)
2951, 2885, 1729, 1645, 1434, 1319, 1231, 1093, 793, cmꢂ1; 1H NMR
(CDCl3, 400 MHz)
(m,1H),1.84e1.94 (m, 3H), 2.24e2.27 (m,1H), 2.48 (d, J¼13.6 Hz,1H),
3.71 (s, 3H), 6.03 (s,1H); 13C NMR (CDCl3,100 MHz)
19.6, 20.7, 27.3,
d
1.01 (d, J¼3.6 Hz, 6H),1.25e131 (m,1H) 1.62e1.69
1620, 1603, 1496, 1453, 1217, 1080, 1029, 743, 699 cmꢂ1 1H NMR
,
d
(CDCl3, 400 MHz)
d
2.31e2.37 (m, 2H), 2.69 (t, J¼7.6 Hz, 2H), 6.04
31.5, 31.6, 38.5, 45.4, 51.4, 63.6, 98.9,149.8,172.3; high-resolution MS
m/e calcd for C12H17BrO2 272.0412, found 272.0404.
(tt, J¼1.6, 13.6 Hz, 1H), 6.15e6.22 (m, 1H), 7.14e7.29 (m, 5H); 13C
NMR (CDCl3, 100 MHz) d 31.3, 34.2, 108.3, 126.0, 128.3, 128.5, 133.8,
141.1; high-resolution MS m/e calcd for C10H11Br 210.0044, found
210.0034. Z isomer as a colorless oil: IR (neat) 3027, 2925, 2657,
4.3.6. 2-(Bromomethylene)-2,3-dihydro-1H-indene 2f. As described
above in method A, purification of the crude product derived from
1 mmol of 1f by flash chromatography on silica gel (elution with
hexane) afforded 163 mg (78%) of 2f as a colorless oil: Rf¼0.65
(Hexane): IR (neat) 3071, 3023, 2904, 2812, 1665, 1607, 1560, 1462,
1387, 1349, 1273, 1204, 1128, 1021, 923, 864, 791, 747, 715, 595,
1621, 1603, 1495, 1453, 1305, 1288, 1077, 1029, 748, 698 cmꢂ1 1H
,
NMR (CDCl3, 400 MHz)
6.07e6.17 (m, 2H), 7.16e7.30 (m, 5H); 13C NMR (CDCl3, 100 MHz)
34.6, 35.0, 104.9, 126.1, 128.3, 128.4, 137.1, 140.8.
d
2.47e2.53 (m, 2H), 2.72 (t, J¼7.1 Hz, 2H),
d
413 cmꢂ1; 1H NMR (CDCl3, 400 MHz)
d
3.72 (d, J¼2.4 Hz, 4H), 6.17 (t,
4.3.11. 5-((E)-2-Bromovinyl)benzo[d][1,3]dioxole 2l.21 As described
above in method B, E/Z analysis (400-MHz 1H NMR integration of
the vinyl protons) of the crude adduct revealed the presence of
a 92:8 ratio of E and Z isomers. Purification of the crude product
derived from 1 mmol of 1l by flash chromatography on silica gel
(elution with hexane) afforded 170 mg (75%) of 2l as a colorless
oil:Rf¼0.45 (Hexane) : IR (neat) 3075, 2893, 1607, 1494, 1442, 1294,
J¼2.0 Hz, 1H), 7.19e7.21 (m 4H); 13C NMR (CDCl3, 100 MHz)
d 38.9,
39.9, 99.3, 124.62, 124.68, 126.7, 126.8, 140.5, 141.2, 145.3; high-
resolution MS m/e calcd for C10H9Br 207.9888, found 207.9892.
4.3.7. (2-Bromoethene-1,1-diyl)dibenzene 2g.17 As described above
in method B, purification of the crude product derived from
1 mmol of 1g by flash chromatography on silica gel (elution with
hexane) afforded 173 mg (67%) of 2g as a colorless oil: Rf¼0.50
1038, 931, 813, 773 cmꢂ1; 1H NMR (CDCl3, 400 MHz)
d 5.94 (s, 2H),
6.58 (d, J¼14.0 Hz, 1H), 6.72e6.73 (m, 2H), 6.79 (d, 1.2 Hz, 1H), 6.99
(Hexane): 1H NMR (CDCl3, 400 MHz)
d
6.76 (s, 1H), 7.19e7.39 (m,
(d, J¼14.0 Hz, 1H); 13C NMR (CDCl3, 100 MHz)
d 101.2, 104.5, 105.4,
108.4, 120.9, 130.3, 136.6, 147.7, 148.1; high-resolution MS m/e calcd
10H); 13C NMR (CDCl3, 100 MHz)
d
105.1, 127.6, 128.2, 128.4, 129.6,
139.0, 140.7, 146.8; high-resolution MS m/e calcd for C14H11Br
for C9H7BrO2 225.9629, found 225.9637.
258.0044, found 258.0038.
4.3.12. 1-((E)-2-Bromovinyl)-4-methoxybenzene 2m.5 As described
above in method B, E/Z analysis (400-MHz 1H NMR integration
of the vinyl protons) of the crude adduct revealed the presence of a
90:10 ratio of E and Z isomers. Purification of the crude product
derived from 1 mmol of 1m by flash chromatography on silica gel
4.3.8. (E)-1-(Bromomethylene)-1,2,3,4-tetrahydronaphthalene
2h.18 As described above in method B, E/Z analysis (400-MHz 1H
NMR integration of the vinyl protons) of the crude adduct revealed
the presence of an 88:12 ratio of E and Z isomers. Purification of the