J. CHEM. RESEARCH (S), 1997 297
ethanol); (Found: C, 56.1; H, 3.3. C10H9ClO3 requires C, 56.4; H,
3.3%); dH 7.79 (1 H, d, 3J 16.0), 7.67 (1 H, d, 4J 2.5), 7.24 (1 H, dd,
3J 8.7 and 4J 2.5), 6.91 (1 H, d, 3J 8.7), 6.67 (1 H, d, 3J 16.0) and 3.48
(3 H, s); dC 116.82 (q), 155.44, 138.50 (q), 130.96, 127.78, 123.02
(q), 122.27 (q), 118.28, 117.69 and 51.29; m/z 214 (Mǹ, 11%), 212
(Mǹ, 29), 182 (37), 180 (100), 154 (33), 152 (94), 127 (11), 125 (36),
99 (12), 89 (44) and 63 (30). 2-Hydroxy-5-nitrobenzaldehyde gave
methyl 3-(2-hydroxy-5-nitrophenyl)propenoate 5 (0.67 g, 75%), mp
198–200 °C (from ethyl acetate); (Found: C, 53.7; H, 4.0; N, 6.0.
C10H9NO5 requires C, 53.85; H, 4.1; N, 6.35%); dH 8.48 (1 H, d, 4J
2.8), 8.17 (1 H, dd, 3J 9.1 and 4J 2.8), 7.80 (1 H, d, 3J 16.3), 7.07 (1 H,
152 (48), 89 (46) and 63 (35). Methyl 3-(2-hydroxy-5-nitro-
phenyl)propenoate [(0.065 g, 0.29 mmol), 140 °C, 750 °C, 5Å10ꢀ3
Torr,
5 min] gave 6-nitrocoumarin 11 (0.042 g, 75%), mp
4
183–184 °C (from toluene) (lit.,11 181–182 °C); dH 8.67 (1 H, d, J
2.7), 8.35 (1 H, dd, 3J 9.0 and 4J 2.7), 8.19 (1 H, d, 3J 9.7), 7.56 (1 H,
d, 3J 9.0) and 6.65 (1 H, d, 3J 9.7); dC 158.84 (q), 157.14 (q), 143.41
(q), 143.22 (q), 126.44, 124.27, 119.00 (q), 118.00 and 117.75; m/z
191 (Mǹ, 100%), 117 (18), 89 (23) and 63 (20). Ethyl 2-methyl-
3-(2-hydroxyphenyl)propenoate [(0.065 g, 0.31 mmol), 100 °C,
750 °C, 5Å10ꢀ3 Torr, 5 min] gave 3-methylcoumarin 12 (0.041 g,
82%), mp 90–92 °C (from ethanol) (lit.,12 69–70 °C); dH 7.86 (1 H,
s), 7.63–7.27 (4 H, m) and 2.09 (3 H, s); dC 159.00 (q), 152.56 (q),
139.47, 130.59, 127.41, 124.82 (q), 124.33, 119.24 (q), 115.82 and
16.60; m/z 160 (Mǹ, 79%), 132 (68), 131 (100), 103 (15) and 77
(29). Ethyl 2-methyl-3-(2-hydroxy-5-chlorophenyl)propenoate
[(0.064 g, 0.27 mmol), 100 °C, 750 °C, 5Å10ꢀ3 Torr, 5 min] gave
3-methyl-6-chlorocoumarin 13 (0.049 g, 96%), mp 158–160 °C
(from ethanol) (lit.,12 158–159 °C); dH 7.79 (1 H, s), 7.70 (1 H, d, 4J
3
3
d, J 9.0), 6.80 (1 H, d, J 16.3) and 3.70 (3 H, s); dC 166.59 (q),
162.35 (q), 139.78 (q), 137.91, 126.80, 124.94, 121.16 (q), 119.91,
116.49 and 51.45; m/z 223 (Mǹ, 26%), 191 (100), 117 (22), 89 (24)
and 63 (13). 2-Hydroxy-1-naphthaldehyde gave methyl
3-(2-hydroxy-1-naphthyl)propenoate
8
(0.77 g, 85%), mp
145–148 °C (from ethyl acetate); (Found: C, 73.3; H, 5.3. C14H12O3
3
requires C, 73.7; H, 5.35%); dH 8.29 (1 H, d, J 16.0), 8.16–7.23
(6 H, m), 6.88 (1 H, d, 3J 16.0) and 3.18 (3 H, s); dC (one quaternary
missing), 160.21 (q), 153.47 (q), 140.58, 133.38, 130.04 (q), 128.95,
128.51, 126.26, 122.42, 116.96, 115.49, 113.02 (q) and 48.70; m/z 228
(Mǹ, 50%), 196 (94), 168 (100), 141 (31), 140 (17), 139 (37) and
115 (26).
2.4), 7.54 (1 H, dd, J 8.8 and J 2.4), 7.38 (1 H, d, J 8.8) and 2.08
(3 H, s); dC 160.68 (q), 151.15 (q), 138.17, 130.13, 128.04 (q),
126.46, 126.20 (q), 120.62 (q), 117,79 and 16.70; m/z 196 (Mǹ,
31%), 194 (Mǹ, 100), 168 (21), 167 (25), 166 (41), 165 (77), 131
(20), 103 (20), 77 (17) and 51 (32). Methyl 3-(2-hydroxy-1-naph-
thyl)propenoate [(0.070 g, 0.30 mmol), 140 °C, 750 °C, 5Å10ꢀ3
Torr, 5 min] gave 5,6-benzocoumarin 14 (0.045 g, 75%), mp
3
4
3
The following compounds were made using ethyl 2-(triphenyl-
phosphoranylidene)propionate (2, R2 = Me) in dichloromethane
under reflux conditions for 1 h. The same molar amounts of
reagents (4 mmol) and similar work-up were used as described in
the general method given above. Salicylaldehyde gave ethyl
3
118–120 °C (from ethanol) (lit.,13 117–118 °C); dH 8.26 (1 H, d, J
3
3
9.8), 8.05 (1 H, d, J 8.3), 7.85–7.45 (4 H, m), 7.28 (1 H, d, J 8.3)
3
and 6.64 (1 H, d, J 9.8); dC (one quaternary missing) 160.76 (q),
2-methyl-3-(2-hydroxyphenyl)propenoate
6
(0.67 g, 82%), mp
153.49 (q), 138.85, 132.86, 129.96 (q), 128.75, 128.47, 125.87,
121.11, 116.66, 115.23 and 112.67 (q); m/z 196 (Mǹ, 100%), 168
(70), 139 (75), 115 (23) and 63 (21).
58–61 °C (from hexane); (Found: C, 69.4; H, 6.8. C12H14O3 requires
C, 69.8; H, 6.8%); dH 7.74 (1 H, s), 7.30–6.79 (4 H, m), 4.18 (2 H,
q), 1.98 (3 H, s) and 1.26 (3 H, t); dC 167.68 (q), 134.36, 129.87,
129.76, 126.62 (q), 122.15 (q), 118.59, 115.76 (q), 115.32, 60.20,
14.07 and 13.92; m/z 206 (Mǹ, 15%), 160 (100), 132 (40), 131 (31)
and 77 (10). 2-Hydroxy-5-chlorobenzaldehyde gave ethyl 2-methyl-
We are grateful to British Petroleum plc for a Research
Studentship (to G. A. C.).
3-(2-hydroxy-5-chlorophenyl)propenoate
7
(0.85 g, 88%), mp
93–95 °C (from n-hexane); (Found: C, 59.8; H, 5.4. C12H13ClO3
requires C, 59.9; H, 5.4%); dH 7.63 (1 H, d, 4J 2.5), 7.26 (1 H, s), 7.21
(1 H, dd, 3J 8.5 and 4J 2.5), 6.90 (1 H, d, 3J 8.5), 4.18 (1 H, q), 1.96
(3 H, s) and 1.25 (3 H, t); dC 167.37 (q), 154.66 (q), 138.18 (q),
132.88, 129.40, 128.87, 128.12 (q), 123.85 (q), 116.94, 60.41, 14.07
and 13.87; m/z 242 (Mǹ, 5%), 240 (Mǹ, 12), 196 (22), 195 (30), 194
(100), 167 (17), 166 (38), 165 (31), 131 (19), 103 (22) and 77
(20).
Received, 8th April 1997; Accepted, 30th April 1997
Paper E/7/02405C
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Preparation of Coumarins by Flash Vacuum Pyrolysis.sThe
appropriate propenoate was distilled at 10ꢀ2–10ꢀ3 Torr into an
empty silica pyrolysis tube (35Å2.5 cm) which was maintained at
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2 R. S. Mali and V. J. Yadav, Synthesis, 1977, 464.
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3
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(2 H, m), 7.34 (2 H, m) and 6.47 (1 H, d, J 9.5); dC 159.90 (q),
153.39 (q), 144.16, 131.88, 128.35, 124.42, 118.63 (q), 116.18 and
116.10; m/z 146 (Mǹ, 91%), 118 (100), 90 (29), 89 (17) and 63 (21).
Methyl 3-(2-hydroxy-5-chlorophenyl)propenoate [(0.060 g, 0.28
mmol), 100 °C, 750 °C, 5Å10ꢀ3 Torr, 5 min] gave 6-chlorocou-
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161–162 °C); dH 8.00 (1 H, d, 3J 9.6), 7.84 (1 H, d, 4J 2.5), 7.63 (1 H,
dd, 3J 8.9 and 4J 2.5), 7.42 (1 H, d, 3J 8.9) and 6.57 (1 H, d, 3J 9.6); dC
159.39 (q), 152.07 (q), 142.98, 131.42, 128.14 (q), 127.47, 120.03 (q),
118.19 and 117.36; m/z 182 (Mǹ, 34%), 180 (Mǹ, 100), 154 (20),
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