Cyclization Reactions of Free and Masked Dianions
Methyl 5-Methylbenzofuran-7-carboxylate (11b) and
Methyl 5-(Chloromethyl)benzofuran-7-carboxylate (11b′).
Starting with 9e (0.200 g, 1.02 mmol) and DDQ (1.157 g, 5.10
mmol) in 1,4-dioxane (20 mL), 11b (0.058 g, 30%) and 11b′
5.24 (dt, J ) 10.5, 1.3 Hz, 1 H, CH
OCH), 5.42 (dt, J ) 17.0, 1.3 Hz, 1 H, CH
(m,1 H, CHdCH ), 6.86 (dd, J ) 7.8, 7.3 Hz, 1 H, CH), 7.30
(dd, J ) 7.3, 1.3 Hz, 1 H, CH), 7.72 (dm, J ) 7.3 Hz, 1 H, CH).
2
dCH), 5.32-5.37 (m, 1 H,
2
dCH), 5.98-6.09
2
1
3
(
0.059 g, 26%) were isolated by chromatography (silica gel,
3 C
C NMR (CDCl , 75 MHz): δ ) 14.3, 34.9, 60.6, 84.2, 113.4,
n-hexane/EtOAc ) 100:1 f 10:1) as slightly yellowish solids.
116.8, 120.0, 128.7, 129.0, 129.6, 136.8, 159.9, 165.2. IR (neat,
1
cm-1): ν˜ ) 2984 (w), 1716 (s), 1609 (w), 1448 (s), 1291 (s), 1263
Compound 11b. Mp ) 60-61 °C. H NMR (CDCl
3
, 300
), 6.75 (d, J
2.2 Hz, 1 H, CH), 7.59 (m, 1 H, CH), 7.72 (d, J ) 2.2 Hz, 1
MHz): δ ) 2.47 (s, 3 H, CH
3
), 4.01 (s, 3 H, OCH
3
(s), 1207 (m), 1171 (w), 1138 (s), 1062 (w), 1031 (w), 985 (w),
+
)
933 (w), 757 (m). MS (EI, 70 eV): m/z (%) ) 218 (M , 100),
1
3
203 (3), 190 (2), 173 (52), 144 (98), 133 (5), 114 (65). HRMS
H, CH), 7.79 (m, 1 H, CH). C NMR (CDCl
3
, 75 MHz): δ
0.8, 52.0, 106.0, 114.2, 126.2, 127.7, 129.1, 131.9, 145.8, 151.6,
65.4. IR (KBr, cm-1): ν˜ ) 3130 (w), 2955 (w), 2922 (w), 1715
C
)
+
2
1
(ESI): calcd for C13
H
14
O
3
[M ] 218.09430, found 218.09608.
1
Compound 14a′. H NMR (CDCl
3
, 300 MHz): δ ) 1.50 (t,
(
s), 1606 (m), 1544 (w), 1441 (s), 1352 (m), 1330 (w), 1297 (s),
257 (s), 1220 (m), 1194 (s), 1127 (s), 087 (w), 909 (w), 872
m), 771 (s). UV-vis (CH Cl , nm): λmax (log ꢀ) ) 228 (4.2),
66 (4.0), 301 (3.7). MS (EI, 70 eV): m/z (%) ) 190 (M , 68),
75 (1), 159 (100), 131 (26). Anal. Calcd for C11
190.198): C 69.47, H 5.30. Found: C 69.36, H 5.46.
J ) 7.2 Hz, 3 H, CH
3
), 4.54 (q, J ) 7.2 Hz, 2 H, OCH
2
), 7.63
1
(t, J ) 7.8 Hz, 1 H, CH), 7.93 (d, J ) 8.6 Hz, 1 H, CH), 8.05 (d,
(
2
2
J ) 8.6 Hz, 1 H, CH), 8.34 (dd, J ) 7.8, 1.3 Hz, 1 H, CH), 8.66
+
13
2
1
(dd, J ) 7.8, 1.3 Hz, 1 H, CH). C NMR (CDCl
3
, 75 MHz): δ
C
H
10
O
3
) 14.4, 61.8, 108.6, 111.1, 114.0, 115.6, 116.8, 117.2, 122.1,
(
124.6, 126.6, 126.8, 132.0, 132.8, 156.1, 157.7, 163.6. IR (neat,
1
cm-1): ν˜ ) 2957 (w), 2925 (m), 2854 (w), 1715 (s), 1671 (s),
Compound 11b′. Mp ) 90 °C. H NMR (CDCl
3
, 300 MHz):
Cl), 6.83 (d, J ) 2.4
Hz, 1 H, CH), 7.79 (d, J ) 2.4 Hz, 1 H, CH), 7.84 (d, J ) 1.8
δ ) 4.02 (s, 3 H, OCH
3
), 4.72 (s, 2 H, CH
2
1615 (m), 1447 (s), 1374 (m), 1291 (s), 1275 (s), 1206 (m), 1179
(s), 1145 (s), 1098 (m), 1023 (m), 929 (w), 756 (w). MS (EI, 70
1
3
eV): m/z (%) ) 290 (M , 19), 264 (38), 261 (31), 249 (83), 244
(65), 217 (14), 193 (19), 188 (49), 161 (13), 148 (41), 142 (14),
129 (20), 115 (53), 102 (13), 101 (46), 87 (100), 74 (43).
+
Hz, 1 H, CH), 8.01 (d, J ) 1.8 Hz, 1 H, CH). C NMR (CDCl
3
,
7
5 MHz): δ
C
) 45.9, 52.4, 106.5, 115.3, 126.4, 127.6, 129.8,
-
1
1
32.3, 146.9, 153.1, 165.0. IR (KBr, cm ): ν˜ ) 2958 (w), 2927
(
w), 1711 (s), 1679 (m), 1609 (w), 1446 (m), 1343 (w), 1307 (m),
Methyl 5-(Chloromethyl)-2-vinyl-2,3-dihydrobenzofu-
ran-7-carboxylate (15b′) and Methyl 5-Methyl-2-vinyl-2,3-
dihydrobenzofuran-7-carboxylate (15b). Starting with 13b
(0.100 g, 0.45 mmol) and DDQ (0.306 g, 1.35 mmol) in 1,4-
dioxane (7 mL), 15b′ (0.020 g, 18%) and 15b (0.035 g, 36%)
were isolated by chromatography (silica gel, n-hexane/EtOAc
) 100:1 f 1:1) as yellowish and slightly yellowish oils,
1
269 (s), 1215 (m), 1198 (s), 1128 (m), 1030 (w), 794 (w), 767
+
37
(
w), 737 (w), 701 (w). MS (EI, 70 eV): m/z (%) ) 226 (M [ Cl],
7
1
), 225 (2), 224 (M+ [ Cl], 20), 193 (14), 189 (100), 167 (2),
35
65 (6), 130 (7).
Ethyl 2,3-dihydrobenzofuran-7-carboxylate (12a). Start-
ing with 9d (0.200 g, 1.02 mmol) and DDQ (0.694 g, 3.06 mmol)
in 1,4-dioxane (10 mL), 12a was isolated by chromatography
respectively.
1
(
silica gel, n-hexane/EtOAc ) 100:1 f 1:1) as a slightly
Compound 15b′. H NMR (CDCl
3
, 300 MHz): δ ) 3.02 (dd,
), 3.37 (dd, J ) 15.6, 9.6 Hz, 1 H,
), 4.55 (s, 2 H, CH Cl), 5.26 (dt, J )
dCH), 5.37-5.41 (m, 1 H, OCH), 5.43
(dt, J ) 17.1, 1.2 Hz, 1 H, CH dCH), 5.97-6.08 (m, 1 H, CHd
CH ), 7.37 (d, J ) 1.8 Hz, 1 H, CH), 7.75 (d, J ) 1.8 Hz, 1 H,
CH). C NMR (CDCl
1
yellowish oil (0.111 g, 57%). H NMR (CDCl
3
, 300 MHz): δ )
), 3.23 (t, J ) 8.7 Hz, 2 H, CH ),
), 4.72 (t, J ) 8.7 Hz, 2 H, OCH ),
.87 (t, J ) 7.5 Hz, 1 H, CH), 7.36 (dd, J ) 7.2, 1.2 Hz, 1 H,
J ) 15.6, 7.2 Hz, 1 H, CH
CH ), 3.91 (s, 3 H, OCH
10.5, 1.2 Hz, 1 H, CH
2
1
4
6
.38 (t, J ) 7.2 Hz, 3 H, CH
3
2
2
3
2
.37 (q, J ) 7.2 Hz, 2 H, OCH
2
2
2
2
1
3
CH), 7.72 (dd, J ) 7.5, 1.2 Hz, 1 H, CH). C NMR (CDCl
3
, 75
2
1
3
MHz): δ
C
) 14.4, 29.0, 60.7, 72.2, 113.4, 120.0, 129.2, 129.3,
3 C
, 75 MHz): δ ) 34.8, 46.0, 52.1, 85.0,
-
1
1
29.6, 160.7, 165.3. IR (neat, cm ): ν˜ ) 2981 (m), 2935 (m),
112.8, 117.5, 129.6, 129.8, 130.0, 130.5, 136.5, 160.1, 165.4.
-
1
2
904 (w), 2864 (w), 1721 (s), 1673 (m), 1605 (s), 1541 (w), 1476
IR (KBr, cm ): ν˜ ) 2951 (w), 2927 (w), 1713 (s), 1616 (w),
(
m), 1444 (s), 1396 (m), 1370 (m), 1294 (s), 1268 (s), 1207 (s),
1445 (m), 1317 (w), 1274 (s), 1242 (m), 1204 (s), 1123 (w), 1009
+
37
1
168 (m), 1135 (s), 1100 (m), 1062 (m), 1026 (m), 994 (m), 930
(w), 959 (w), 935 (w). MS (EI, 70 eV): m/z (%) ) 254 (M [ Cl],
35
+
(
m), 890 (w), 866 (w), 843 (w), 800 (w), 758 (s). UV-vis (CH
2
-
7), 252 (M [ Cl], 30), 221 (12), 217 (95), 192 (10), 185 (100),
171 (18), 157 (43), 128 (39), 105 (29). HRMS (ESI): calcd for
Cl
2
, nm): λmax (log ꢀ) ) 228 (3.8), 319 (3.4). MS (EI, 70 eV):
+
+
37
35
m/z (%) ) 192 (M , 38), 177 (4), 163 (12), 147 (100), 119 (4),
13 3
C H13ClO [M ] 254.05237 ( Cl), 252.05533 ( Cl), found
+
37
35
9
1 (20). HRMS (ESI): calcd for C11
H O
12 3
([M + Na] ) 215.06841,
254.05228 ( Cl), 252.05554 ( Cl).
Compound 15b. H NMR (CDCl , 300 MHz): δ ) 2.29 (s,
3 H, CH ), 2.96 (dd, J ) 15.6, 7.2 Hz, 1 H, CH
15.6, 9.3 Hz, 1 H, CH ), 3.90 (s, 3 H, OCH ), 5.23 (dt, J ) 10.5,
1.2 Hz, 1 H, CH dCH), 5.31-5.34 (m, 1 H, OCH), 5.40 (dt, J
) 17.1, 1.2 Hz, 1 H, CH dCH), 5.97-6.08 (m, 1 H, CHdCH ),
7.13 (s, 1 H, CH), 7.53 (s, 1 H, CH). C NMR (CDCl , 75
MHz): δ ) 20.5, 35.1, 51.9, 84.4, 112.4, 117.1, 128.9, 129.6,
found 215.74301.
1
3
Ethyl 2-Vinylbenzofuran-7-carboxylate (14a), Ethyl
-Vinyl-2,3-dihydrobenzofuran-7-carboxylate (15a), and
3
2
), 3.36 (dd, J )
2
2
3
Ethyl 8,9-Dicyanodibenzofuran-4-carboxylate (14a′). Start-
ing with 13a (0.100 g, 0.45 mmol) and DDQ (0.306 g, 1.35
mmol) in 1,4-dioxane (7 mL), 14a (0.017 g, 18%), 15a (0.062
g, 63%), and 14a′ (0.005 g, 4%) were isolated by chromatog-
raphy (silica gel, n-hexane/EtOAc ) 100:1 f 1:1) as slightly
yellowish oils and as a yellowish solid, respectively.
2
2
2
1
3
3
C
-
1
129.7, 130.3, 136.9, 157.9, 166.1. IR (neat, cm ): ν˜ ) 2953
(w), 2925 (s), 2856 (w), 1715 (s), 1679 (s), 1611 (w), 1465 (s),
1441 (s), 1376 (w), 1349 (m), 1272 (s), 1237 (s), 1201 (s), 1120
(m), 1088 (w), 1027 (w), 990 (w), 937 (w), 790 (w). MS (EI, 70
eV): m/z (%) ) 218 (M , 85), 203 (5), 187 (28), 171 (6), 158
(100), 147 (18), 130 (52), 119 (10), 114 (55), 91 (21).
1
Compound 14a. H NMR (CDCl
), 4.40 (q, J ) 7.2 Hz, 2 H, OCH
dCH), 6.00 (dd, J ) 17.4, 0.9
dCH), 6.56 (s, 1 H, CH), 6.60 (dd, J ) 17.4, 11.2,
), 7.18 (dd, J ) 15.4, 2.4 Hz, 1 H, CH), 7.63 (dd,
3
, 300 MHz): δ ) 1,42 (t,
J ) 7.2 Hz, 3 H, CH
3
2
), 5.39
+
(
dd, J ) 11.2, 1.2 Hz, 1 H, CH
2
Hz, 1 H, CH
2
1
H, CHdCH
2
Methyl 5-Phenyl-2-vinylbenzofuran-7-carboxylate (14c)
and Methyl 5-Phenyl-2-vinyl-2,3-dihydrobenzofuran-7-
carboxylate (15c). Starting with methyl 5-phenyl-2-vinyl-
2,3,3a,4,5,6-hexahydrobenzofuran-7-carboxylate (13c) (0.150
g, 0.53 mmol) and DDQ (0.359 g, 1.6 mmol) in 1,4-dioxane (10
mL), 14c (0.027 g, 18%) and 15c (0.064 g, 43%) were isolated
after chromatography (silica gel, n-hexane/EtOAc ) 100:1 f
1:1) as a yellowish oil and solid, respectively.
J ) 7.7, 1.2 Hz, 1 H, CH), 7.86 (dd, J ) 7.7, 1.2 Hz, 1 H, CH).
1
3
C NMR (CDCl
3 C
, 75 MHz): δ ) 14.4, 61.1, 104.1, 115.1, 116.9,
1
22.6, 124.9, 125.8, 127.0, 130.6, 153.3, 155.8, 165.1. IR (neat,
-
1
cm ): ν˜ ) 2961 (s), 2926 (s), 2858 (w), 1725 (s), 1674 (m),
1
1
(
1
609 (w), 1456 (m), 1426 (m), 1392 (w), 1375 (m), 1286 (s),
263 (s), 1221 (w), 1180 (m), 1116 (s), 1095 (s), 1024 (s), 867
+
w), 780 (s), 756 (m). MS (EI, 70 eV): m/z (%) ) 216 (M , 94),
88 (40), 173 (31), 171 (100), 143 (9), 114 (50).
Compound 14c.
3 H, OCH ), 5.48 (dd, J ) 11.1, 1.2 Hz, 1 H, CH
(dd, J ) 17.4, 1.2 Hz, 1 H, CH dCH), 6.69 (s, 1 H, CH), 6.70
(dd, J ) 17.4, 11.1 Hz, 1 H, CHdCH
), 7.37-7.66 (m, 5 H, 5 ×
1
3
H NMR (CDCl , 300 MHz): δ ) 4.04 (s,
1
Compound 15a. H NMR (CDCl
3
, 300 MHz): δ ) 1.38 (t,
), 3.00 (dd, J ) 15.7, 7.3 Hz, 1 H, CH ),
.39 (dd, J ) 15.7, 9.4 Hz, 1 H, CH ), 433-4.41 (m, 2 H, OCH ),
3
2
dCH), 6.11
J ) 7.2 Hz, 3 H, CH
3
2
2
3
2
2
2
J. Org. Chem, Vol. 70, No. 24, 2005 10025