Pd-Catalyzed Suzuki Cross-Coupling of 2-Haloselenophenes
Hz, 1H), 7.00-6.98 (m, 1H). 13C NMR: CDCl3, 100 MHz, δ
(ppm): 130.2, 129.7, 129.5, 127.8, 126.7, 125.9, 124.5, 124.4. MS
(EI, 70 eV) m/z (relative intensity): 214 (85), 134 (100), 121 (10),
108 (20), 89 (23). HRMS Calcd for C8H6SSe: 213.9355. Found:
213.9361.
CDCl3, 100 MHz, δ (ppm): 149.4, 137.4, 133.7, 129.6, 125.9,
125.6, 21.1. MS (EI, 70 eV) m/z (relative intensity): 312 (100),
309 (26), 215 (26), 154 (20), 115 (27), 101 (10), 89 (7). HRMS
Calcd for C18H16Se: 312.0417. Found: 312.0424.
2,5-Bis-(3-(trifluoromethyl)phenyl)selenophene (6c). Yield:
1
1
2-o-Tolylselenophene (3e). Yield: 0.060 g (55%). H NMR:
0.151 g (72%). H NMR: CDCl3, 400 MHz, δ (ppm): 7.80 (s,
CDCl3, 400 MHz, δ (ppm): 8.02 (d, J ) 5.55 Hz, 1H), 7.39-7.37
2H), 7.71 (d, J ) 7.64 Hz, 2H), 7.57-7.49 (m, 6H). 13C NMR:
CDCl3, 100 MHz, δ (ppm): 149.0, 136.8, 131.5 (q, J ) 32.53 Hz),
129.5, 129.3, 127.4, 124.3 (q, J ) 3.53 Hz), 123.9 (q, J ) 272.68
Hz), 122.6 (q, J ) 3.53 Hz). MS (EI, 70 eV) m/z (relative
intensity): 420 (100), 418 (48), 340 (13), 270 (16), 210 (16). HRMS
Calcd for C18H10F6Se: 419.9852. Found: 419.9858.
(m, 1H), 7.33-7.31 (m, 1H), 7.26-7.18 (m, 4H), 2.41 (s, 3H). 13
C
NMR: CDCl3, 100 MHz, δ (ppm): 149.4, 136.3, 135.7, 130.7,
130.6, 130.5, 129.6, 128.6, 127.7, 125.8, 29.7. HRMS Calcd for
C11H10Se: 221.9948. Found: 221.9955.
1
2-Mesitylselenophene (3f). Yield: 0.039 g (32%). H NMR:
CDCl3, 400 MHz, δ (ppm): 8.04 (d, J ) 5.55 Hz, 1H), 7.31-7.29
(m, 1H), 6.93-6.92 (m, 3H), 2.31 (s, 3H), 2.14 (s, 6H). 13C NMR:
CDCl3, 100 MHz, δ (ppm): 148.1, 137.6, 133.1, 130.9, 130.2,
129.5, 128.6, 128.1, 21.0, 20.8. MS (EI, 70 eV) m/z (relative
intensity): 252 (14), 250 (74), 235 (32), 169 (100), 155 (41), 128
(29), 115 (26). HRMS Calcd for C13H14Se: 250.0261. Found:
250.0266.
2-(3-(Trifluoromethyl)phenyl)selenophene (3g). Yield: 0.099
g (72%). 1H NMR: CDCl3, 400 MHz, δ (ppm): 7.98 (d, J ) 5.55
Hz, 1H), 7.78 (s, 1H), 7.69 (d, J ) 7.75 Hz, 1H), 7.58-7.43 (m,
2H), 7.45 (t, J ) 7.75 Hz, 1H), 7.33-7.31 (m, 1H). 13C NMR:
CDCl3, 100 MHz, δ (ppm): 148.9, 137.2, 131.5 (q, J ) 32.53 Hz),
131.2, 130.7, 129.6, 129.4, 126.4, 124.0 (q, J ) 3.53 Hz), 123.9
(q, J ) 272,68 Hz), 122.9 (q, J ) 3.53 Hz). MS (EI, 70 eV) m/z
(relative intensity): 276 (100), 196 (48), 175 (13), 146 (23), 126
(10), 115 (11). HRMS Calcd for C11H7F3Se: 275.9665. Found:
275.9671.
2-(3-Nitrophenyl)selenophene (3h). Yield: 0.081 g (65%). 1H
NMR: CDCl3, 400 MHz, δ (ppm): 8.38 (s, 1H), 8.10 (d, J ) 7.89
Hz, 1H), 8.04 (d, J ) 5.55 Hz, 1H), 7.83 (d, J ) 7.60 Hz, 1H),
7.57 (d, J ) 3.51 Hz, 1H), 7.52 (t, J ) 8.04 Hz, 1H), 7.37-7.34
(m, 1H). 13C NMR: CDCl3, 100 MHz, δ (ppm): 167.7, 147.6,
138.1, 132.3, 131.9, 130.8, 129.8, 127.1, 121.9, 120.7. MS (EI, 70
eV) m/z (relative intensity): 253 (9), 207 (7), 127 (14), 115 (100).
HRMS Calcd for C10H7NO2Se: 252.9642. Found: 252.9648.
2,5-Bis-phenylselenophene (6a). Yield: 0.078 g (55%). 1H
NMR: CDCl3, 400 MHz, δ (ppm): 7.56 (d, J ) 7.60 Hz, 4H),
7.44 (s, 2H), 7.38-7.23 (m, 6H). 13C NMR: CDCl3, 100 MHz, δ
(ppm): 149.9, 136.4, 128.9, 127.6, 126.2, 126.1. MS (EI, 70 eV)
m/z (relative intensity): 284 (100), 280 (22), 203 (53), 142 (14),
101 (30). HRMS Calcd for C16H12Se: 284.0104. Found: 284.0110.
General Procedure for the Synthesis of Diaryl Ketones from
2-Iodoselenophene. A dried Schlenk flask containing Pd(PPh3)4
(0.017 g, 3 mol %) and boronic acid (0.75 mmol) was evacuated
and connected to an atmosphere of argon. 2-Iodoselenophene (0.128
g, 0.5 mmol), toluene (3 mL), and aqueous Na2CO3 (1.1 mL of
solution 2 M in H2O, 2.17 mmol) were added. After removal of
argon atmosphere, the system was purged with CO three times using
a balloon. The mixture was stirred at 110 °C under carbon monoxide
atmosphere (balloon) for 12 h. The resulting mixture was quenched
by addition of NH4Cl solution (10 mL) and then extracted with
EtOAc (3 × 10 mL). The combined organic extracts were dried
with MgSO4, filtered, and evaporated under reduced pressure. The
crude products were purified by flash column chromatography
(EtOAc/hexane, 20:80).
Selenophen-2-yl(p-tolyl)methanone (7a). Yield: 0.101 g (81%).
1H NMR: CDCl3, 400 MHz, δ (ppm): 8.40 (d, J ) 5.55 Hz, 1H),
7.83 (d, J ) 3.95 Hz, 1H), 7.76 (d, J ) 8.04 Hz, 2H), 7.42-7.39
(m, 1H), 7.28 (d, J ) 8.04 Hz, 2H), 2.43 (s, 3H). 13C NMR: CDCl3,
100 MHz, δ (ppm): 189.0, 150.7, 139.9, 136.8, 130.5, 130.1, 129.3,
129.0, 128.8, 21.5. MS (EI, 70 eV) m/z (relative intensity): 252
(13), 250 (69), 159 (74), 119 (100), 91 (75). HRMS Calcd for
C12H10OSe: 249.9897. Found: 249.9904.
1-(4-(Selenophen-2-yl)phenyl)ethanone (3i). Yield: 0.094 g
1
(76%). H NMR: CDCl3, 400 MHz, δ (ppm): 8.02 (d, J ) 5.55
Hz, 1H), 7.93 (d, J ) 8.33 Hz, 2H), 7.62 (d, J ) 8.33 Hz, 2H),
7.58 (d, J ) 3.51 Hz, 1H), 7.35-7.33 (m, 1H), 2.59 (s, 3H). 13C
NMR: CDCl3, 100 MHz, δ (ppm): 197.2, 149.2, 140.7, 135.8,
131.8, 130.8, 129.1, 126.8, 126.1, 26.5. MS (EI, 70 eV) m/z (relative
intensity): 250 (9), 235 (100), 207 (5), 126 (25), 115 (99). HRMS
Calcd for C12H10OSe: 249.9897. Found: 249.9905.
(4-Methoxyphenyl)(selenophen-2-yl)methanone (7b). Yield:
1
0.107 g (80%). H NMR: CDCl3, 400 MHz, δ (ppm): 8.38 (d, J
) 5.55 Hz, 1H), 7.87 (d, J ) 8.77 Hz, 2H), 7.82 (d, J ) 3.65 Hz,
1H), 7.41-7.39 (m, 1H), 6.96 (d, J ) 8.77 Hz, 2H), 3.86 (s, 3H).
13C NMR: CDCl3, 100 MHz, δ (ppm): 187.9, 162.9, 150.7, 139.4,
136.2, 132.0, 131.4, 130.4, 130.2, 55.3. MS (EI, 70 eV) m/z (relative
intensity): 266 (53), 264 (29), 251 (13), 159 (38), 135 (100), 77
(40). HRMS Calcd for C12H10O2Se: 265.9846. Found: 265.9852.
2-(4-Chlorophenyl)selenophene (3j). Yield: 0.113 g (94%). 1H
NMR: CDCl3, 400 MHz, δ (ppm): 7.91 (d, J ) 5.55 Hz, 1H),
7.44 (d, J ) 8.33 Hz, 2H), 7.42-7.38 (m, 1H), 7.30-7.27 (m,
3H). 13C NMR: CDCl3, 100 MHz, δ (ppm): 149.3, 134.9, 130.6,
130.4, 128.9, 128.1, 127.5, 125.6. MS (EI, 70 eV) m/z (relative
intensity): 244 (6), 242 (100), 162 (69), 126 (26), 115 (27). HRMS
Calcd for C10H7ClSe: 241.9401. Found: 241.9407.
General Procedure for the Preparation of the Bis-arylsele-
nophene from 2,5-Diiodoselenophene. The solution of 2,5-
diiodoselenophene (0.096 g, 0.25 mmol) in DME (5 mL) was added,
under argon, to a mixture of Pd(OAc)2 (0.003 g, 6 mol %) and
boronic acid (0.7 mmol). The resulting solution was stirred for 30
min at room temperature. After this time, the solution was added
to the solution of K2CO3 (2.4 mmol, 0.309 g) in H2O (1.2 mL).
The mixture was then heated at reflux for the time indicated in
Scheme 3, cooled to room temperature, diluted with dichlo-
romethane (20 mL), and washed with brine (2 × 20 mL). The
organic phase was separated, dried over MgSO4, and concentrated
under vacuum. The residue was purified by flash chromatography
and eluted with hexane/ethyl acetate (95:5) or hexane.
(4-Chlorophenyl)(selenophen-2-yl)methanone (7c). Yield: 0.093
g (69%). 1H NMR: CDCl3, 400 MHz, δ (ppm): 8.45 (d, J ) 5.55
Hz, 1H), 7.81-7.77 (m, 3H), 7.45 (d, J ) 8.48 Hz, 2H), 7.43-
7.40 (m, 1H). 13C NMR: CDCl3, 100 MHz, δ (ppm): 188.0, 149.9,
140.7, 138.4, 137.1, 135.9, 130.7, 130.5, 128.6. MS (EI, 70 eV)
m/z (relative intensity): 270 (52), 159 (100), 139 (40), 111 (42),
75 (38). HRMS Calcd for C11H7ClOSe: 269.9351. Found: 269.9357.
Mesityl(selenophen-2-yl)methanone (7d). Yield: 0.074 g (53%).
1H NMR: CDCl3, 400 MHz, δ (ppm): 8.42 (d, J ) 5.55 Hz, 1H),
7.49 (d, J ) 3.97 Hz, 1H), 7.33-7.29 (m, 1H), 6.88 (s, 2H), 2.31
(s, 3H), 2.17 (s, 6H). 13C NMR: CDCl3, 100 MHz, δ (ppm): 193.9,
151.4, 141.2, 138.5, 137.4, 134.0, 130.9, 128.2, 128.1, 21.0, 19.2.
MS (EI, 70 eV) m/z (relative intensity): 280 (18), 278 (89), 197
(100), 169 (33), 147 (26), 119 (25), 91 (40). HRMS Calcd for
C14H14OSe: 278.0210. Found: 278.0216.
Phenyl(selenophen-2-yl)methanone (7e). Yield: 0.049 g (42%).
1H NMR: CDCl3, 400 MHz, δ (ppm): 8.42 (d, J ) 5.55 Hz, 1H),
7.84-7.79 (m, 3H), 7.59-7.41 (m, 1H), 7.49-7.41 (m, 3H). 13C
NMR: CDCl3, 100 MHz, δ (ppm): 189.3, 150.4, 140.3, 137.3,
132.0, 130.6, 129.9, 129.0, 128.3. MS (EI, 70 eV) m/z (relative
2,5-Bis-p-tolylselenophene (6b). Yield: 0.148 g (95%). 1H
NMR: CDCl3, 400 MHz, δ (ppm): 7.44 (d, J ) 7.65 Hz, 4H),
7.36 (s, 2H), 7.14 (d, J ) 7.61 Hz, 4H), 2.34 (s, 6H). 13C NMR:
J. Org. Chem, Vol. 71, No. 10, 2006 3791