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Copper Pincer Complexes as Advantageous Catalysts for the Heteroannulation
1308C under argon. After cooling, H2O (5.0 mL) was added
and the resulting aqueous suspension was extracted with
ethyl acetate (315 mL). The organic layer was washed
with H2O (15 mL) and brine (215 mL), dried over anhy-
drous Na2SO4, and concentrated under vacuum. The crude
product was purified by flash chromatography, using ethyl
acetate/hexane as eluent, to provide pure derivatives 3 and
4.
(%)=225 (M+, 100), 224 (47); HR-MS: m/z=225.0929,
calcd. for C15H13O2: 225.0916.
2-(4-Methoxyphenyl)benzofuran (3e):[28] Yield: 86%;
white powder; mp 147–1508C; 1H NMR (300 Hz, CDCl3):
d=7.80 (d, J=8.8 Hz, 2H), 7.57–7.49 (m, 2H), 7.29–7.19 (m,
2H), 6.99 (d, J=8.8 Hz, 2H), 6.89 (s, 1H), 3.87 (s, 3H);
13C NMR (75.4 MHz, CDCl3): d=160.0, 156.1, 154.7, 129.5,
126.4, 123.7, 123.4, 122.8, 120.6, 114.3, 111.0, 99.7, 55.4; IR
(film): n=1505, 1298, 1251, 1023 cmÀ1; MS: m/z (%)=225
(M+, 100), 224 (56); HR-MS: m/z=225.0926, calcd. for
C15H13O2: 225.00916.
2-Phenylbenzo[b]furan (3a):[24] Yield: 99%; white
1
powder; mp 118–1198C; H NMR (300 Hz, CDCl3): d=7.92
(d, J=7.2 Hz, 2H), 7.63 (d, J=7.3 Hz, 1H), 7.58 (d, J=
8.2 Hz, 1H), 7.50 (t, J=7.5 Hz, 2H), 7.40 (t, J=7.4 Hz, 1H),
7.34 (t, J=6.1 Hz, 1H), 7.28 (t, J=7.4 Hz, 1H), 7.07 (s, 1H);
13C NMR (75.4 MHz, CDCl3): d=155.9, 154.9, 130.5, 129.2,
128.8, 128.5, 124.9, 124.2, 122.9, 120.9, 111.2, 101.3; IR
(film): n=1868, 1843, 1556 cmÀ1; MS: m/z (%)=195 (M+,
100), 166 (36); HR-MS: m/z=195.0736, calcd. for C14H11O:
195.0732.
2-(4-Trifluoromethoxyphenyl)benzofuran (3b): Yield:
87%; white powder; mp 159–1618C; 1H NMR (300 Hz,
CDCl3): d=7.91 (d, J=8.8 Hz, 2H), 7.63 (d, J=7.6 Hz, 1H),
7.56 (d, J=8.1 Hz, 1H), 7.35–7.28 (m, 4H), 7.05 (s, 1H);
13C NMR (75.4 MHz, CDCl3): d=155.0, 154.5, 149.2, 129.2,
129.3, 129.0, 126.3, 124.7, 123.1, 121.5, 121.3, 121.1, 111.2,
101.9; IR (film): n=1500, 1451, 1256, 1207, 1157 cmÀ1; MS:
m/z (%)=279 (M+, 100), 278 (60); HR-MS: m/z=279.0634,
calcd. for C15H10F3O2: 279.0633.
2-[3,5-Bis(trifluoromethyl)phenyl]benzofuran
(3f):[29]
Yield: 85%; brown powder; mp 147–1508C; 1H NMR
(300 Hz, CDCl3): d=8.27 (s, 2H), 7.83 (s, 1H), 7.65 (d, J=
7.5 Hz, 1H), 7.55 (d, J=8.1 Hz, 1H), 7.38 (t, J=7.5 Hz,
1H), 7.32–7.23 (m, 2H); 13C NMR (75.4 MHz, CDCl3): d=
155.2, 152.5, 132.6, 132.5, 132.1, 128.5, 125.7, 125.0, 124.6,
123.6, 121.6, 121.5, 121.4, 111.5, 104.2; MS: m/z (%)=359
(29), 332 (M+1, 15), 331 (M+, 98), 330 (MÀ1, 56), 311 (100);
HR-MS: m/z=331.0545, calcd. for C16H9F6O: 331.0558.
2-(3,5-Dimethoxyphenyl)benzofuran (3g):[30] Yield: 79%;
pale yellow powder; mp 48–518C; 1H NMR (300 Hz,
CDCl3): d=7.61 (d, J=7.1 Hz, 1H), 7.56 (d, J=8.7 Hz, 1H),
7.33 (dt, J=7.3, 1.3 Hz, 1H), 7.29–7.25 (m, 1H), 7.07 (d, J=
2.3 Hz, 2H), 7.04 (s, 1H), 6.52 (t, J=2.3 Hz, 1H), 3.91 (s,
6H); 13C NMR (75.4 MHz, CDCl3): d=161.1, 155.7, 154.9,
132.3, 129.1, 124.4, 123.0, 121.0, 111.2, 103.1, 101.9, 101.1,
55.5; IR (film): n=2958, 2836, 1599, 1450, 1333 cmÀ1; MS:
m/z (%)=255 (M+, 100), 254 (36); HR-MS: m/z=255.1034,
calcd. for C16H15O3: 255.1021.
2-(4-tert-Butylphenyl)benzofuran (3c):[25] Yield: >99%;
white powder; mp 127–1298C; 1H NMR (300 Hz, CDCl3):
d=7.85 (d, J=8.5 Hz, 2H), 7.61 (d, J=7.7 Hz, 1H), 7.56 (d,
J=8.1 Hz, 1H), 7.51 (d, J=8.5 Hz, 2H), 7.33–7.25 (m, 2H),
7.02 (s, 1H), 1.41 (s, 9H); 13C NMR (75.4 MHz, CDCl3): d=
156.2, 154.9, 151.8, 129.4, 127.8, 125.7, 124.8, 124.0, 122.9,
120.8, 111.1, 100.7, 34.8, 31.3; MS: m/z (%)=251 (M+, 100),
250 (80); HR-MS: m/z=251.1444, calcd. for C18H19O:
251.1436.
2-(4-Methoxy-2-methylphenyl)benzofuran (3j): Yield:
82%; pale yellow powder; mp 129–1338C; 1H NMR
(300 Hz, CDCl3): d=7.82 (d, J=8.2 Hz, 1H), 7.63 (d, J=
8.2 Hz, 1H), 7.55 (d, J=8.3 Hz, 1H), 7.33–7.26 (m, 2H),
6.90–6.88 (m, 2H), 6.83 (s, 1H), 3.89 (s, 3H), 2.61 (s, 3H);
13C NMR (75.4 MHz, CDCl3): d=159.7, 155.8, 154.2, 137.6,
129.7, 129.4, 123.8, 122.9, 122.7, 120.6, 116.6, 111.5, 110.9,
103.8, 55.3, 22.0; IR (film): n=2956, 2833, 1606, 1496, 1453,
1255 cmÀ1; MS: m/z (%)=239 (M+, 100), 238 (60); HR-MS:
m/z=239.1096, calcd. for C16H15O2: 239.1072.
2-(3-Chlorophenyl)benzofuran (3k):[26] Yield: >99%;
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yellow oil; H NMR (300 Hz, CDCl3): d=7.89 (s, 1H), 7.77
(d, J=8.7 Hz, 1H), 7.63 (d, J=7.6 Hz, 1H), 7.55 (d, J=
8.2 Hz, 1H), 7.42–7.27 (m, 5H), 7.08 (s, 1H); 13C NMR
(75.4 MHz, CDCl3): d=155.0, 154.4, 134.9, 132.2, 130.1,
128.9, 128.4, 124.9, 124.8, 123.3, 123.0, 121.1, 111.3, 102.4; IR
(film): n=1603, 1558, 1470, 1453 cmÀ1; MS: m/z (%)=230
(M+1, 33), 229 (M+, 100), 228 (61), 193 (36); HR-MS:
m/z=229.0437, calcd. for C14H10ClO: 229.0420.
2-(6-Methoxy-2-naphthyl)-1-benzofuran (3h):[31] Yield:
59%; pale yellow powder; mp 193–1958C; 1H NMR
(300 Hz, CDCl3): d=8.31 (s, 1H), 7.91–7.78 (m, 3H), 7.62–
7.55 (m, 2H), 7.33–7.16 (m, 4H), 7.09 (s, 1H), 3.95 (s, 3H);
13C NMR (75.4 MHz, CDCl3): d=158.3, 156.3, 154.9, 134.6,
129.9, 129.4, 128.9, 127.3, 125.7, 124.1, 123.8, 123.4, 122.9,
120.8, 119.4, 111.1, 105.9, 101.1, 55.4 cmÀ1; MS: m/z (%)=
275 (M+, 100), 274 (66); HR-MS: m/z=275.1090, calcd. for
C19H15O2: 275.1072.
2-(4-Bromophenyl)benzofuran (3d):[24a] Yield: 77%; white
1
powder; mp 150–1548C; H NMR (300 Hz, CDCl3): d=7.75
(d, J=8.6 Hz, 2H), 7.62–7.59 (m, 3H), 7.55 (d, J=8.7 Hz,
1H), 7.33 (dt, J=8.3, 1.2 Hz, 1H), 7.28 (d, J=8.3 Hz, 1H),
7.05 (s, 1H); 13C NMR (75.4 MHz, CDCl3): d=154.9. 154.8,
132.0, 129.4, 129.1, 126.4, 124.6, 123.1, 122.5, 121.0, 111.2,
101.9; MS: m/z (%)=275 (M+2, 65), 274 (M+1, 92), 273
(M+, 68), 272 (MÀ1, 82), 194 (100); HR-MS: m/z=
272.9926, calcd. for C14H10BrO: 272.9915.
2-PhenylfuroACTHNUTRGNEUNG
[3,2-b]pyridine (4a):[32] Yield: >99%; brown
powder; mp 91–938C; 1H NMR (300 Hz, CDCl3): d=8.55
(d, J=4.8 Hz, 1H), 7.92 (d, J=8.4 Hz, 2H), 7.77 (d, J=
8.2 Hz, 1H), 7.49 (t, J=7.3 Hz, 2H), 7.42 (t, J=7.2 Hz, 1H),
7.24 (s, 1H), 7.22–7.19 (m, 1H); 13C NMR (75.4 MHz,
CDCl3): d=159.7, 149.0, 148.0, 146.0, 129.7, 129.6, 128.9,
125.3, 118.8, 117.8, 102.4; MS: m/z (%)=196 (M+, 100);
HR-MS: m/z=196.0767, calcd. for C13H10NO: 196.0762.
2-Phenylbenzofuran-6-carboxyclic acid (3m): Yield: 93%;
pale yellow powder; mp 189–1928C; 1H NMR (300 Hz,
MeOD): d=8.17 (s, 1H), 7.95–7.92 (m, 3H), 7.66 (d, J=
8.1 Hz, 1H), 7.49 (t, J=7.4 Hz, 2H), 7.41 (t, J=7.3 Hz, 1H),
7.27 (s, 1H); 13C NMR (75.4 MHz, MeOH-d4): d=169.6,
2-(2-Methoxyphenyl)benzofuran (3i):[27] Yield: 88%;
1
yellow powder; mp 80–828C; H NMR (300 Hz, CDCl3): d=
8.18 (d, J=7. 7 Hz, 1H), 7.69 (d, J=7.2 Hz, 1H), 7.61 (d,
J=7.8 Hz, 1H), 7.46 (s, 1H), 7.41–7.26 (m, 3H), 7.16 (t, J=
7.4 Hz, 1H), 7.04 (d, J=8.3 Hz, 1H), 4.02 (s, 3H); 13C NMR
(75.4 MHz, CDCl3): d=156.6, 154.0, 152.3, 129.9, 129.3,
127.1, 124.2, 122.8, 121.1, 120.8, 119.4, 111.1, 110.9, 106.5,
55.5; IR (film): n=2939, 1492, 1446, 1282 cmÀ1; MS: m/z
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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