208 JOURNAL OF CHEMICAL RESEARCH 2018
1
1639 and 1484 (C=C, arom), 1208 (Csp –O), 1095 (Csp –O); H NMR
phosphine with an alkyl X-phenylpropiolate and 2-hydroxy-1-
naphthaldehyde as an OH acid at room temperature. As various
substituted alkyl X-phenylpropiolates can be used, a wide
variety of benzochromenes can be produced by this method,
some of which might display biological activity.
2
3
(400 MHz, CDCl3): δ 1.35 (t, 3H, 3JHH = 6.8 Hz, CH3), 4.28–4.35 (m, 2H,
OCH2), 6.4 (s, 1H, CH), 7.08 (d, 1H, 3JHH = 8.4 Hz, CHarom), 7.24 (d, 2H,
3JHH = 8.4 Hz, 2CHarom), 7.37–7.4 (m, 2H, 2CHarom), 7.42 (td, 1H, 3JHH
=
6.4 Hz, 4JHH = 0.8 Hz, CHarom), 7.59 (td, 1H, 3JHH = 7.8 Hz, 4JHH = 1.2 Hz,
CHarom), 7.77 (d, 2H, 3JHH = 8.4 Hz, 2CHarom), 8.11 (d, 1H, 3JHH = 8.4 Hz,
CHarom), 8.41 (s, 1H, CHvinyl); 13C NMR (100 MHz, CDCl3): δ 14.3 (CH3),
61.1 (OCH2), 74.2 (CH), 113.3 (Cq), 118.1 (CH), 121.3 (CH), 122.1 (Cq),
124.4 (CH), 127.7 (CH), 128.6 (2CH), 128.7 (2CH), 128.8 (CH), 129.3
(Cq), 129.5 (CH), 130.6 (Cq), 133.1 (CH),134.5 (Cq), 137.6 (Cq), 152.6
(Cq), 165 (C=O); MS m/z: 366 (M+ + 2, 34), 364 (M+, 100), 337 (5),
335 (16), 321 (1), 319 (3), 293 (35), 291 (100), 253 (12). Anal. calcd for
C22H17O3Cl: C, 72.43; H, 4.70; found: C, 72.68; H, 4.72%.
Experimental
Triphenylphosphine and 2-hydroxy-1-naphthaldehyde (2) were
obtained from Fluka (Buche, Switzerland) and were used without
further purification. Solvents were dried before use. Alkyl aryl
propiolates (3a–g) were synthesised according to a reported method.22
Bis(4-methoxyphenyl)(phenyl)phosphine was prepared via a literature
method.23 IR spectra were recorded on a FTIR Bruker Vector 22
spectrometer. Mass spectra were recorded on a Finnigan-Matt 8430
mass spectrometer operating in electron impact mode. Elemental
analyses were performed using a Heraeus CHN–O rapid analyser.
NMR spectra were obtained on a Brucker Vector 22 spectrometer
(1H NMR at 400 MHz, 13C NMR at 100 MHz) in CDCl3 using TMS as
an internal standard. Chemical shifts (δ) are given in ppm and coupling
constants (J) are given in Hz. Melting points were measured on an
Electrothermal 9100 apparatus.
Methyl
2-(2-chlorophenyl)-3H-benzo[f]chromene-3-carboxylate
(4d): Yellow powder; yield 0.228 g (65%); m.p. 107–109 °C; IR (KBr)
(cm−1): 3060 (Csp –H), 2942 and 2849 (Csp –H), 1712 (C=O), 1632
and 1433 (C=C,2 arom), 1194 (Csp –O), 1043 (Csp –O); 1H NMR
3
2
3
(400 MHz, CDCl3): δ 3.82 (s, 3H, OCH3), 6.93 (s, 1H, CH), 7.01 (d, 1H,
3JHH = 9.2 Hz, CHarom), 7.07 (t, 1H, 3JHH = 7.6 Hz, CHarom), 7.23 (td, 1H,
3JHH = 7.8 Hz, 4JHH = 1.6 Hz, CHarom), 7.34 (dd, 1H, 3JHH = 7.8 Hz, 4JHH
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3
= 1.6 Hz, CHarom), 7.42 (t, 1H, JHH = 7.6 Hz, CHarom), 7.47 (d, 1H, JHH
= 8.0 Hz, CHarom), 7.61 (t, 1H, 3JHH = 7.6. Hz, CHarom), 7.73 (d, 1H, 3JHH
= 8.8 Hz, CHarom), 7.76 (d, 1H, 3JHH = 8.4 Hz, CHarom), 8.17 (d, 1H, 3JHH
= 8.4 Hz, CHarom), 8.57 (s, 1H, CHvinyl); 13C NMR (100 MHz, CDCl3): δ
52.1 (OCH3), 71.5 (CH), 113 (Cq), 118.3 (CH), 121.0 (Cq), 121.2 (CH),
124.3 (CH), 126.9 (CH), 127.7 (CH), 128.8 (CH), 129.2 (CH), 129.4
(Cq), 130.3 (2CH), 130.5 (Cq), 130.6 (CH), 133.1 (CH), 134.2 (Cq), 134.9
(Cq), 152.5 (Cq), 165.1 (C=O); MS m/z: 352 (M+ + 2, 18), 350 (M+, 56),
337 (1.5), 335 (4), 315 (8), 293 (33), 291 (100), 239 (27). Anal. calcd for
C21H15O3Cl: C, 71.90; H, 4.31; found: C, 71.64; H, 4.32%.
Synthesis of benzochromenes 4a–g; general procedure
A solution of 3a–g (1 mmol) in CH2C12 (2 mL) was added dropwise to
a magnetically stirred solution of phosphine 1 (1 mmol) and 2-hydroxy-
1-naphthaldehyde (0.172 g, 1 mmol) in CH2Cl2 (5 mL) over 10 min
at 0 °C. The reaction mixture was then allowed to warm up to room
temperature and stirred for 10–24 h. The solvent was removed under
reduced pressure and the residue was purified by silica gel (Merck
silica gel, 230–400 mesh) column chromatography using n-hexane/
ethyl acetate (9:1) as eluent. The solvent was removed under reduced
pressure and the products 4a–g were obtained.
Ethyl
2-(2-chlorophenyl)-3H-benzo[f]chromene-3-carboxylate
Ethyl 2-phenyl-3H-benzo[f]chromene-3-carboxylate (4a): Yellow
powder; yield 0.106 g (32%); m.p. 109–111 °C; IR (KBr) (cm−1): 3052
(4e): Yellow powder; yield 0.246 g (62%); m.p. 110–112 °C; IR
(KBr) (cm−1): 3063 (Csp –H), 2977 and 2859 (Csp –H), 1714 (C=O),
1629 and 1465 (C=C, ar2om), 1194 (Csp –O), 1066 3(Csp –O); H NMR
1
(Csp –H), 2989 (Csp –H), 1695 (C=O), 1630 and 1451 (C=C), 1271
3
(Csp2–O), 1199 (Csp –O); H NMR (400 MHz, CDCl3): δ 1.22 (t, 3H,
(400 MHz, CDCl3): δ 1.3 (t, 3H, JHH2= 7.2 Hz, CH33), 4.26 (q, 2H,
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3
2
3
3
3JHH = 7.2 Hz, CH3), 4.18 (q, 2H, JHH = 7.2 Hz, OCH2), 6.33 (s, 1H,
3
3JHH = 7.2 Hz, OCH2), 6.94 (s, 1H, CH), 7.01 (d, 1H, JHH = 8.8 Hz,
3
CHarom), 7.08 (td, 1H, 3JHH = 7.6 Hz, 4JHH = 1.2 Hz, CHarom), 7.23 (td, 1H,
3JHH = 7.6 Hz, 4JHH = 1.6 Hz, CHarom), 7.35 (dd, 1H, 3JHH = 7.6 Hz, 4JHH
CH), 6.96 (d, 1H, JHH = 8.0 Hz, CHarom), 7.13–7.14 (m, 3H, 3CHarom),
7.25 (t, 1H, 3JHH = 8.0 Hz, CHarom), 7.33–7.34 (m, 2H, 2CHarom), 7.43 (t,
1H, 3JHH = 8.0 Hz, CHarom), 7.6 (d, 1H, 3JHH = 8.0 Hz, CHarom), 7.61 (d,
1H, 3JHH = 8.0 Hz, CHarom), 7.97 (d, 1H, 3JHH = 8.0 Hz, CHarom), 8.29 (s,
1H, CHvinyl); 13C NMR (100 MHz, CDCl3): δ 14.3 (CH3), 61.0 (OCH2),
75.0 (CH), 113.4 (Cq), 118.2 (CH), 121.4 (CH), 122.5 (Cq), 124.2 (CH),
127.2 (CH), 127.6 (CH), 128.5 (CH), 128.6 (CH), 128.8 (CH), 129.3
(CH), 129.3 (Cq), 130.7 (Cq), 132.9 (CH), 139.2 (Cq), 153 (Cq), 165.2
(C=O); MS m/z: 330 (M+, 32), 301 (9), 285 (3), 257 (100), 228 (13).
Anal. calcd for C22H18O3: C, 79.98; H, 5.49; found: C, 79.76; H, 5.51%.
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4
= 1.6 Hz, CHarom), 7.42 (td, 1H, JHH = 7.6 Hz, JHH = 0.8 Hz, CHarom),
7.47 (dd, 1H, 3JHH = 8 Hz, 4JHH = 0.8 Hz, CHarom), 7.61 (td, 1H, 3JHH = 7.8
Hz, 4JHH = 1.2 Hz, CHarom), 7.73 (d, 1H, 3JHH = 8.8 Hz, CHarom), 7.77 (d,
1H, 3JHH = 8.0 Hz, CHarom), 8.18 (d, 1H, 3JHH = 8.4 Hz, CHarom), 8.55 (s,
1H, CHvinyl); 13C NMR (100 MHz, CDCl3): δ 14.2 (CH3), 61 (OCH2),
71.6 (CH), 112.9 (Cq), 118.3 (CH), 121.2 (CH), 121.6 (Cq), 124.3
(CH), 126.9 (CH), 127.6 (CH), 128.8 (CH), 129.2 (CH), 129.3 (Cq),
130.2 (3CH), 130.5 (Cq), 133 (CH), 134 (Cq), 135.1 (Cq), 152.5 (Cq),
164.7 (C=O); ); MS m/z: 366 (M+ + 2, 25), 364 (M+, 84), 337 (3),
335 (8), 321 (1), 319 (3), 293 (31), 291 (100), 253 (12). Anal. calcd. for
C22H17O3Cl: C, 72.43; H, 4.70; found: C, 72.71; H, 4.69%.
Methyl
2-(4-chlorophenyl)-3H-benzo[f]chromene-3-carboxylate
(4b): Yellow powder; yield 0.147 g (42%); m.p. 118–120 °C; IR (KBr)
(cm−1): 3053 (Csp –H), 2942 and 2845 (Csp –H), 1703 (C=O), 1628
2
3
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and 1438 (C=C, arom), 1195 (Csp –O), 1089 (Csp –O); H NMR (400
Methyl
2-[4-(trifluoromethyl)phenyl]-3H-benzo[f]chromene-3-
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3
MHz, CDCl3): δ 3.86 (s, 3H, OCH3), 6.4 (s, 1H, CH), 7.08 (d, 1H,
carboxylate (4f): Yellow powder; yield 0.23 g (60%); m.p. 110–113 °C;
3JHH = 8.4 Hz, CHarom), 7.24 (d, 2H, 3JHH = 8.8 Hz, 2CHarom), 7.37–7.40
IR (KBr) (cm−1): 3065(Csp –H), 2948 and 2854 (Csp –H), 1706 (C=O),
2
3
3
4
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(m, 2H, 2CHarom), 7.42 (td, 1H, JHH = 7.4 Hz, JHH = 1.2 Hz, CHarom),
7.59 (td, 1H, 3JHH = 7.8 Hz, 4JHH = 1.2 Hz, CHarom), 7.77 (d, 2H, 3JHH = 8.8
Hz, 2CHarom), 8.11 (d, 1H, 3JHH = 8.4 Hz, CHarom), 8.43 (s, 1H, CHvinyl);
13C NMR (100 MHz, CDCl3): δ 52.1 (OCH3), 74.1 (CH), 113.3 (Cq),
118.1 (CH), 121.3 (CH), 121.7 (Cq), 124.4 (CH), 127.7 (CH), 128.6
(2CH), 128.7 (2CH), 128.8 (CH), 129.4 (Cq), 129.8 (Cq), 130.6 (Cq),
133.2 (CH), 134.5 (Cq), 137.4 (Cq), 152.7 (Cq), 165.4 (C=O); MS m/z:
352 (M+ + 2, 26), 350 (M+, 73), 337 (2.5), 335 (8), 321 (1), 319 (3), 293
(33), 291 (100), 239 (22). Anal. calcd for C21H15ClO3: C, 71.90; H, 4.31;
found: C, 72.07; H, 4.32%.
1623 and 1445 (C=C, arom), 1274 (Csp –O), 1067 (Csp –O); H NMR
(400 MHz, CDCl3): δ 3.88 (s, 3H, OCH32), 6.48 (s, 1H, CH), 7.11 (d, 1H,
3JHH = 8.4 Hz, CHarom), 7.42 (td, 1H, 3JHH = 7.6 Hz, 4JHH = 1.2 Hz, CHarom),
7.53 and 7.57 (4H, ABq, 3JHH = 8.4 Hz, 4CHarom), 7.61 (td, 1H, 3JHH = 7.8
Hz, 4JHH = 1.2 Hz, CHarom), 7.77 (d, 1H, 3JHH = 8.4 Hz, CHarom), 7.79 (d, H,
3JHH = 8.8 Hz, CHarom), 8.09 (d, 1H, 3JHH = 8.4 Hz, CHarom), 8.45 (s, 1H,
CHvinyl); 13C NMR (100 MHz, CDCl3): δ 52.2 (OCH3), 74 (CH), 113.3
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(Cq), 117.9 (CH), 121.3 (CH), 121.4 (Cq), 123.9 (Cq, q, JCF = 272.1 Hz
) 124.5 (CH), 125.5 (2CH, q, 3JCF = 3.7 Hz ), 127.4 (2CH), 127.8 (CH),
128.8 (CH), 129.4 (Cq), 130.1 (CH), 130.6 (Cq), 130.636(Cq, q, 2JCF = 32.3
Hz ) 133.4 (CH), 142.9 (Cq), 152.7 (Cq), 165.4 (C=O); MS m/z: 384 (M+,
100), 369 (18), 353 (4), 325 (100), 339 (39). Anal. calcd for C22H15O3F3:
C, 68.75; H, 3.93; found: C, 69.01; H, 3.94%.
Ethyl
2-(4-chlorophenyl)-3H-benzo[f]chromene-3-carboxylate
(4c): Yellow powder; yield 0.157 g (43%); m.p. 121–123 °C; IR
(KBr) (cm−1): 3078 (Csp –H), 2921 and 2858 (Csp –H), 1695 (C=O),
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3