T. Kubo et al.
13C NMR (68 MHz, CDCl3, 258C): d=0.41, 21.63, 99.11, 103.75, 122.77,
126.04, 128.31, 133.39, 133.80, 140.70 ppm; IR (neat): n˜ =2960 (m), 2922
(w), 2898 (w), 2163 (m), 1602 (w), 1485 (m), 1447 (w), 1391 (w), 1251
(m), 1227 (m), 1045 (m), 877 (m), 843 (bm), 820 (m), 776 (w), 760 (m),
700 (w), 675 (w), 633 (w), 562 cmꢀ1 (w); MS (EI, 70 eV): m/z (rel. intensi-
ty): 268 ([M+2]+, 23), 266 ([M]+, 21), 253 (65), 251 (66), 149 (100); ele-
mental analysis (%) calcd for C12H15BrSi: C 53.93, H 5.66, Br 29.90, Si
10.51; found: C 53.97, H 5.76.
1H NMR (270 MHz, CDCl3, 258C): d=0.28 (s, 9H), 7.52 (d, J=8.1 Hz,
1H), 7.88 (dd, J=1.9, 8.1 Hz, 1H), 8.22 ppm (d, J=1.6 Hz, 1H);
13C NMR (100 MHz, CDCl3, 258C): d=ꢀ0.22, 52.45, 102.28, 103.24,
125.55, 127.74, 129.27, 129.51, 130.78, 133.23, 165.13 ppm; IR (neat): n˜ =
3069 (w), 2956 (s), 2899 (w), 2844 (w), 2163 (m), 2068 (w), 1944 (w), 1730
(s), 1597 (s), 1548 (w), 1489 (w), 1436 (m), 1385 (m), 1287 (s), 1251 (s),
1111 (s), 1044 (m), 972 (w), 871 (s), 845 (s), 803 cmꢀ1 (w); MS (EI,
70 eV): m/z (rel. intensity): 312 ([M+2]+, 23), 310 ([M]+, 23), 297 (100),
295 (99); HRMS (EI): m/z calcd for C13H15BrO2Si: 310.0025; found:
310.0001.
2-Iodo-4-methyl-1-(2-trimethylsilylethynyl)benzene
(7):
nBuLi
(1.6 molLꢀ1, 3.8 mL, 6.1 mmol) was added to a solution of 4 (1.35 g,
5.04 mmol) in THF (30 mL) at ꢀ708C under N2. The reaction mixture
was stirred at this temperature for 15 min and then I2 (2.20 g, 8.68 mmol)
was added. The reaction mixture was allowed to warm to ambient tem-
perature and diluted with n-hexane (50 mL). The solution was washed
with saturated aqueous NaS2O3, water, and brine. The organic layer was
dried over anhydrous Na2SO4. The filtrate was evaporated, and the resi-
due was purified by distillation (ca. 1208C, 1.5 mmHg) to give 7 as a col-
orless oil (1.21 g, 76%). 1H NMR (270 MHz, CDCl3, 258C): d=0.28 (s,
9H), 2.29 (brs, 3H), 7.08 (brd, J=8.1 Hz, 1H), 7.34 (d, J=8.1 Hz, 1H),
7.6 ppm (s, 1H); 13C NMR (68 MHz, CDCl3, 258C): d=ꢀ0.15, 20.89,
97.79, 101.16, 106.66, 126.70, 128.61, 132.36, 139.21, 140.07 ppm; IR
(neat): n˜ =3056 (w), 3028 (w), 2959 (m), 2920 (w), 2898 (w), 2161 (m),
1906 (w), 1595 (w), 1549 (w), 1477 (m), 1446 (w), 1408 (w), 1387 (w),
1332 (w), 1251 (m), 1225 (w), 1140 (w), 1038 (m), 995 (w), 872 (s), 844
(s), 820 (m), 760 (m), 700 cmꢀ1 (w); MS (EI, 70 eV): m/z (rel. intensity):
314 ([M]+, 34), 299 (73), 149 (95), 105 (100); elemental analysis (%)
calcd for C12H15ISi: C 45.87, H 4.81, I 40.38, Si 8.94; found: C 46.21, H
4.74.
2-Bromo-1-ethynyl-4-methylbenzene (15): K2CO3 (16.1 g) was added to a
solution of 2-bromo-4-methyl-1-(2-trimethylethynyl)benzene (4) in THF
(20 mL) and methanol (80 mL) under N2. The suspension was stirred for
12 h at ambient temperature and quenched with water (100 mL). The re-
action mixture was extracted with n-hexane (2ꢂ100 mL). The combined
organic layers were washed with water and brine and dried over anhy-
drous Na2SO4. The filtrate was evaporated and the residue was purified
by column chromatography on silica gel (40 g). From a hexane fraction,
15 was obtained as a pale-yellow oil (2.51 g, 75%). 1H NMR (270 MHz,
CDCl3, 258C): d=2.33 (s, 3H), 3.31 (s, 1H), 7.06 (d, J=7.8 Hz, 1H), 7.40
(d, J=7.9 Hz, 1H), 7.42 ppm (s, 1H); 13C NMR (68 MHz, CDCl3, 258C):
d=21.09, 80.94, 82.01, 121.23, 125.28, 127.91, 132.95, 133.75, 140.66 ppm;
IR (neat): n˜ =3293 (s), 3030 (w), 2921 (w), 2864 (w), 2110 (w), 1908 (w),
1602 (m), 1484 (s), 1043 (m), 862 (m), 820 (s) 710 (w), 677 cmꢀ1 (m); MS
(EI, 70 eV): m/z (rel. intensity): 196 ([M+2]+, 64), 194 ([M]+, 65), 115
(100); elemental analysis (%) calcd for C9H7Br: C 53.42, H 3.62, Br
40.96; found: C 55.69, H 3.70.
Ethyl 3-(2-bromo-4-methylphenyl)propiolate (16):
A solution of 2-
2-Bromo-1-(2-trimethylsilylethynyl)benzene (9): A solution of 2-bromo-
1-iodobenzene (5.32 g, 18.8 mmol), [PdCl2ACHTNUTRGNE(UNG PPh3)2] (0.256 g, 0.36 mmol),
bromo-1-ethynyl-4-methylbenzene 15 (0.789 g, 4.78 mmol) in THF
(5 mL) was added to a solution of LDA, which was generated from diiso-
propylamine (1.25 mL) and nBuLi (1.6m, 5.5 mL, 8.8 mmol) in THF
(10 mL), at ꢀ708C under N2. The reaction mixture was stirred at this
temperature for 20 min and then ethyl chloroformate (1.6 mL,
16.7 mmol) was added. The mixture was allowed to warm to ambient
temperature, quenched with aqueous ammonium chloride, and extracted
with n-hexane/ethyl acetate. The organic layer was washed with water
and brine and dried over anhydrous Na2SO4. The filtrate was evaporated
and the residue was purified by column chromatography on silica gel
(10 g, toluene/n-hexane=3:1) to give 16 as a pale-yellow oil (0.766 g,
60%). 1H NMR (270 MHz, CDCl3, 258C): d=1.35 (t, J=7.3 Hz, 3H),
2.35 (s, 3H), 4.30 (q, J=7.0 Hz, 2H), 7.08–7.12 (m, 1H), 7.44–7.45 (m,
1H), 7.47 ppm (d, J=7.8 Hz, 1H); 13C NMR (68 MHz, CDCl3, 258C):
d=14.10, 21.28, 62.08, 84.01, 84.30, 119.38, 126.37, 128.13, 133.38, 134.57,
142.69, 153.89 ppm; IR (neat): n˜ =2982 (w), 2212 (w), 1422 (m), 1709 (s),
1601 (w), 1488 (w), 1446 (w), 1390 (w), 1366 (w), 1297 (m), 1259 (m),
1194 (m), 1142 (w), 1095 (w), 1050 (w), 1021 cmꢀ1 (w); MS (EI, 70 eV):
m/z (rel. intensity): 268 ([M+2]+, 29), 266 ([M]+, 30), 223 (71), 221 (78),
copper(I) iodide (0.037 g, 0.19 mmol), triethylamine (100 mL), and trime-
thylsilylacetylene (3.2 mL, 22.4 mmol) was stirred for 12 h under N2. The
reaction mixture was diluted with n-hexane (50 mL) and washed with hy-
drochloric acid (6 molLꢀ1), water, and brine. The organic layer was dried
over anhydrous Na2SO4. The filtrate was evaporated, and the residue was
purified by distillation (ꢂ1008C, 1.5 mmHg) to give 9 as a yellow oil
(2.86 g, 60%). 1H NMR (270 MHz, CDCl3, 258C): d=0.28 (s, 9H), 7.15
(m, J=7.6, 1.9 Hz, 1H), 7.23 (m, J=7.6, 1.4 Hz, 1H), 7.49 (m, J=7.6,
1.6 Hz, 1H), 7.57 ppm (m, J=7.8, 1.4 Hz, 1H).
1-Bromo-3,4-dimethoxy-5-(2-trimethylsilylethynyl)benzene (10): A solu-
tion of 1-bromo-2-iodo-4,5-dimethoxybenzene (2.17 g, 6.32 mmol),
[PdCl2ACHTUNGTRENNUNG(PPh3)2] (0.094 g, 0.13 mmol), copper(I) iodide (0.044 g,
0.26 mmol), triethylamine (15 mL), and trimethylsilylacetylene (2.2 mL,
15.4 mmol) was stirred at 508C for 12 h under N2. The reaction mixture
was diluted with n-hexane/ethyl acetate (2:1, 50 mL) and washed with hy-
drochloric acid (6 molLꢀ), water, and brine. The organic layer was dried
over anhydrous Na2SO4. The filtrate was evaporated and the residue was
purified by distillation (140?1608C, 1.5 mmHg) to give 10 as a yellow
solid (1.17 g, 59%). M.p. 88.9–89.38C; 1H NMR (270 MHz, CDCl3,
258C): d=0.27 (s, 9H), 3.86 (s, 3H), 3.87 (s, 3H), 6.96 (s, 1H), 7.01 ppm
(s, 1H); 13C NMR (68 MHz, CDCl3, 258C): d=ꢀ0.08, 56.09, 56.16, 97.63,
103.81, 115.09, 115.41, 117.06, 117.16, 147.96, 149.97 ppm; IR (neat): n˜ =
3004 (w), 2960 (w), 2898 (w), 2844 (w), 2156 (m), 1599 (m), 1564 (w),
1508 (s), 1482 (w), 1442 (m), 1383 (w), 1332 (w), 1265 (s), 1248 (s), 1218
(s), 1200 (m), 1171 (m), 1047 (w), 1030 (w), 974 (m), 953 (w), 864 (s), 842
(s), 802 (m), 762 (m), 706 cmꢀ1 (w); MS (EI, 70 eV): m/z (rel. intensity):
314 ([M+2]+, 85), 312 ([M]+, 83), 299 (97), 297 (100); elemental analysis
(%) calcd for C13H17BrO2Si: C 49.84, H 5.47, Br 25.51, O 10.21, Si 8.97;
found: C 50.21, H 5.44.
196 (93), 194 (100); HRMS
267.0015; found: 267.0000.
(ESI): m/z calcd for C12H12O2Br [M+H]+:
ACHTUNGTRENNUNG
1-(2-Bromo-4-methylphenyl)-2-(4-methylphenyl)ethyne (12): A solution
of 15 (0.68 g, 3.48 mmol), para-iodotoluene (0.70 g, 3.21 mmol), [PdCl2-
AHCTUNTGREG(NUNN PPh3)2] (0.062 g, 0.09 mmol), copper(I) iodide (0.025 g, 0.13 mmol), and
triethylamine (30 mL) was stirred for 12 h at ambient temperature under
N2. The reaction mixture was diluted with n-hexane (50 mL); washed
with hydrochloric acid (6 molmLꢀ1), water, and brine; and dried over an-
hydrous Na2SO4. The filtrate was evaporated and the residue was purified
by distillation under reduced pressure (220–2508C, 2 mmHg) to give 12
as a colorless solid (0.78 g, 85%). M.p. 81.5–82.28C; 1H NMR (270 MHz,
CDCl3, 258C): d=2.34 (s, 3H), 2.37 (s, 3H), 7.08 (m, 1H), 7.16 (d, J=
8.6 Hz, 1H), 7.17 (m, 1H), 7.42 (2H, AA’XX’), 7.46 ppm (2H, AA’XX’);
13C NMR (68 MHz, CDCl3, 258C): d=21.10, 21.52, 87.53, 93.37, 120.08,
122.57, 125.32, 127.93, 129.11, 131.52, 132.82, 132.95, 138.61, 139.79 ppm;
IR (KBr): n˜ =3025 (w), 2916 (w), 2215 (w), 1909 (w), 1597 (w), 1557 (w),
1511 (s), 1480 (m), 1260 (w), 1208 (w), 1179 (w), 1105 (w), 1040 (m),
1018 (w), 957 (w), 945 (w), 876 (w), 817 (s), 762 (w), 708 cmꢀ1 (w); MS
(EI, 70 eV): m/z (rel. intensity): 286 ([M+2]+, 93), 284 ([M]+, 100), 205
(38), 189 (48); elemental analysis (%) calcd for C16H13Br: C 67.39, H
4.59, Br 28.02; found: C 67.09, H 4.55.
Methyl 3-bromo-4-[(trimethylsilyl)ethynyl]benzoate (11): A solution of
methyl 3-bromo-4-iodobenzoate (8.59 g, 25.2 mmol), [PdCl2ACTHNUTRGEN(UNG PPh3)2]
(0.72 g, 1.02 mmol), copper(I) iodide (0.103 g, 0.54 mmol), triethylamine
(100 mL), and trimethylsilylacetylene (11 mL, 77.3 mmol) was stirred at
508C for 12 h under N2. The reaction mixture was diluted with n-hexane/
ethyl acetate (2:1, 50 mL) and washed with hydrochloric acid (6 molLꢀ1),
water, and brine. The organic layer was dried over anhydrous Na2SO4.
The filtrate was evaporated, and the residue was purified by distillation
(130–1408C, 1.5 mmHg) to give 11 as
a yellow oil (2.33 g, 30%).
2658
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 2653 – 2661