Annulated Anthracenes, Carbazoles, and Thiophenes
hexane) to give aldehyde 6a (0.71 g, 83%) as a thick liquid. 1H
NMR (300 MHz, CDCl3): δ = 10.26 (s, 1 H, CHO), 7.98–7.91 (m,
= 8.01 (d, J = 7.8 Hz, 1 H, ArH), 7.32 (t, J = 7.5 Hz, 1 H, ArH),
7.21 (t, J = 7.5 Hz, 1 H, ArH), 6.92–6.83 (m, 3 H, ArH), 6.74 (d,
1 H, ArH), 7.80–7.75 (m, 2 H, ArH), 7.43 (t, J = 7.4 Hz, 1 H, J = 7.5 Hz, 1 H, ArH), 4.31 (s, 2 H, CH2), 2.22 (s, 3 H, CH3), 2.11
ArH), 7.36–7.28 (m, 3 H, ArH), 7.26–7.15 (m, 3 H, ArH), 7.09 (t, (s, 3 H, CH3) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 173.2, 143.4,
J = 7.2 Hz, 1 H, ArH), 4.53 (s, 2 H, CH2), 4.15 (t, J = 7.2 Hz, 2 136.8, 135.8, 135.5, 133.0, 131.6, 131.0, 130.6, 129.6, 128.4, 126.6,
H, CH2), 1.74 (t, J = 7.2 Hz, 2 H, CH2), 1.34–1.19 (m, 6 H, CH2, 126.0, 36.9, 20.9, 19.5 ppm.
CH3), 0.78 (t, J = 6.6 Hz, 3 H, CH2) ppm. 13C NMR (75.4 MHz,
CDCl3): δ = 192.5, 144.3, 140.8, 139.2, 134.0, 131.6, 130.6, 126.8,
2-(3,4-Dimethoxybenzyl)benzoic Acid (5e): Keto acid 4e (2 g,
6.99 mmol), upon reduction using zinc dust (3.01 g, 46.03 mmol)
126.7, 125.6, 124.0, 123.1, 122.6, 120.8, 120.4, 120.4, 118.6, 108.8,
and mercuric chloride (0.30 g, 1.10 mmol) following a procedure
108.7, 43.2, 38.0, 31.6, 29.0, 27.0, 22.6, 14.1 ppm.
similar to that described for 5a, gave benzyl acid 5e (1.57 g, 83%)
1
as a thick liquid. H NMR (300 MHz, CDCl3): δ = 7.99–7.96 (m,
1 H, ArH), 7.59–7.49 (m, 1 H, ArH), 7.42–7.36 (m, 1 H, ArH),
7.26–7.23 (m, 1 H, ArH), 7.15–7.12 (m, 1 H, ArH), 6.71 (s, 1 H,
ArH), 6.62–6.58 (m, 1 H, ArH), 4.31 (s, 2 H, CH2), 3.74 (s, 3 H,
OCH3), 3.73 (s, 3 H, OCH3) ppm. 13C NMR (75.4 MHz, CDCl3):
δ = 172.9, 148.7, 147.2, 143.7, 133.2, 132.9, 131.5, 131.4, 126.2,
121.0, 120.1, 112.5, 111.1, 55.8, 55.7, 39.1 ppm. DEPT-135
(75.4 MHz, CDCl3): δ = 131.9, 130.5, 125.3, 120.0, 111.5, 110.1,
108.9, 55.8, 55.7, 39.1 ppm.
5-Hexyl-5H-naphtho[2,3-c]carbazole (7a): BF3·OEt2 (0.03 g,
0.21 mmol) was added to a solution of aldehyde 6a (0.4 g,
1.1 mmol) in dry CH2Cl2 (10 mL). The reaction mixture was stirred
for 10 min at room temperature under a nitrogen atmosphere. The
solvent was removed in vacuo, and the residue was purified by col-
umn chromatography (1% EtOAc in hexane) to give 7a (0.35 g,
1
92%) as a pale green solid, m.p. 104–106 °C. H NMR (300 MHz,
CDCl3): δ = 9.22 (s, 1 H, ArH), 8.74 (d, J = 7.2 Hz, 1 H, ArH),
8.51 (s, 1 H, ArH), 8.15 (d, J = 8.4 Hz, 1 H, ArH), 8.05–7.95 (m,
2 H, ArH), 7.62 (d, J = 9.3 Hz, 1 H, ArH), 7.57–7.50 (m, 2 H,
ArH), 7.49–7.44 (m, 3 H, ArH), 4.38 (t, J = 6.9 Hz, 2 H, CH2),
1.88 (t, J = 6.8 Hz, 2 H, CH2), 1.30–1.25 (m, 6 H, CH2), 0.87–0.82
(m, 3 H, CH3) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 138.8,
137.3, 132.5, 130.0, 128.7, 128.3, 128.0, 127.9, 127.9, 125.7, 124.3,
124.0, 123.5, 121.8, 120.7, 120.1, 113.2, 112.4, 110.0, 43.2, 31.6,
29.8, 27.0, 22.6, 14.1 ppm. DEPT-135 (75.4 MHz, CDCl3): δ =
128.3, 128.0, 128.0, 127.9, 125.7, 124.3, 123.5, 121.8, 120.7, 120.1,
112.4, 109.6, 43.2, 31.6, 29.8, 27.0, 22.6, 14.1 ppm. HRMS (EI):
calcd. for C26H25N [M]+ 351.1987; found 351.1980.
2-(Biphenyl-4-ylmethyl)benzoic Acid (5f): Keto acid 4f (3 g,
9.93 mmol), upon reduction using zinc dust (4.37 g, 65.56 mmol)
and mercuric chloride (0.43 g, 1.58 mmol) following a procedure
similar to that described for 5a, gave benzyl acid 5f (2.63 g, 88%) as
a colourless solid, m.p. 166–168 °C. 1H NMR (300 MHz, CDCl3): δ
= 7.99 (d, J = 7.5 Hz, 1 H, ArH), 7.61–7.54 (m, 3 H, ArH), 7.53–
7.48 (m, 3 H, ArH), 7.42–7.38 (m, 2 H, ArH), 7.37 (d, J = 7.4 Hz,
1 H, ArH), 7.35–7.33 (m, 1 H, ArH), 7.30 (d, J = 4.2 Hz, 1 H,
ArH), 7.25 (t, J = 6.3 Hz, 1 H, CH2), 4.50 (s, 2 H, CH2) ppm. 13C
NMR (75.4 MHz, CDCl3): δ = 172.4, 143.4, 141.0, 139.9, 139.0,
133.1, 131.9, 131.8, 129.5, 128.9, 128.7, 128.4, 127.7, 127.5, 127.2,
127.1, 127.0, 126.5, 39.3 ppm. DEPT-135 (75.4 MHz, CDCl3): δ =
133.0, 131.8, 131.8, 129.4, 128.9, 128.7, 127.7, 127.5, 127.2, 127.1,
127.0, 126.5, 122.9, 39.3 ppm.
2-(4-Methylbenzyl)benzoic Acid (5b): Zinc dust (4.3 g, 65.75 mmol)
and mercuric chloride (0.43 g, 1.58 mmol) were added to a mixture
of distilled water (5.5 mL) and conc. HCl (0.2 mL). The mixture
was stirred until it became homogeneous ca. 0.5 h). To this solu-
tion, distilled water (2.7 mL), conc. HCl (0.65 mL), toluene
(3.6 mL), 1,4-dioxane (3.6 mL), and keto acid 4b (2.4 g, 9.99 mmol)
were added. The reaction mixture was heated at reflux for 48 h,
and conc. HCl (1.8 mL) was added every 6 h. Usual work-up fol-
lowing a procedure similar to that described for 5a gave benzyl acid
5b (1.72 g, 75%) as a colourless solid, m.p. 112–114 °C (ref.[19] 111–
2-[(4-Methylnaphthalen-1-yl)methyl]benzoic Acid (5g): Keto acid 4g
(2 g, 6.36 mmol), upon reduction using zinc dust (2.97 g,
45.41 mmol) and mercuric chloride (0.29 g, 1.06 mmol) following a
procedure similar to that described for 5a, gave benzyl acid 5g
(1.77 g, 93%) as a colourless solid, m.p. 152–154 °C. 1H NMR
(300 MHz, CDCl3): δ = 8.12 (d, J = 7.5 Hz, 1 H, ArH), 8.03 (d, J
= 8.1 Hz, 1 H, ArH), 7.91 (d, J = 7.8 Hz, 1 H, ArH), 7.50–7.43
(m, 2 H, ArH), 7.33–7.23 (m, 3 H, ArH), 7.06 (d, J = 7.2 Hz, 1 H,
ArH), 6.92 (d, J = 6.9 Hz, 1 H, ArH), 4.88 (s, 2 H, CH2), 2.69 (s,
3 H, CH3) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 173.0, 143.5,
134.5, 134.1, 133.1, 132.3, 131.7, 130.9, 129.1, 128.3, 127.2, 126.4,
126.2, 125.9, 125.7, 125.5, 124.8, 36.9, 19.5 ppm.
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112 °C). H NMR (300 MHz, CDCl3): δ = 7.89 (d, J = 7.8 Hz, 1
H, ArH), 7.28 (t, J = 7.3 Hz, 1 H, ArH), 7.12 (t, J = 7.5 Hz, 1 H,
ArH), 7.04 (d, J = 7.5 Hz, 1 H, ArH), 6.91–6.88 (m, 4 H, ArH),
4.25 (s, 2 H, CH2), 2.15 (s, 3 H, CH3) ppm. 13C NMR (75.4 MHz,
CDCl3): δ = 173.5, 143.9, 137.7, 135.5, 133.0, 131.7, 129.1, 129.0,
128.5, 128.3, 126.3, 39.2, 21.1 ppm. DEPT-135 (75.4 MHz, CDCl3):
δ = 133.0, 131.7, 129.1, 129.0, 128.3, 1263, 39.2, 21.1 ppm.
2-[(2,3-Dihydro-1H-inden-5-yl)methyl]benzoic Acid (5h): Keto acid
4h (2 g, 7.51 mmol), upon reduction using zinc dust (3.24 g,
49.54 mmol) and mercuric chloride (0.32 g, 1.17 mmol) following a
procedure similar to that described for 5a, gave benzyl acid 5h
(1.33 g, 71%) as a colourless solid, m.p. 76–78 °C. 1H NMR
(300 MHz, CDCl3): δ = 8.05–8.02 (m, 1 H, ArH), 7.91 (d, J =
7.8 Hz, 1 H, ArH), 7.67–7.65 (m, 1 H, ArH), 7.55–7.44 (m, 1 H,
ArH), 7.30–7.20 (m, 1 H, ArH), 7.19–7.04 (m, 1 H, ArH), 7.01–
6.92 (m, 1 H, ArH), 4.41 (s, 2 H, CH2), 2.87–2.80 (m, 4 H, CH2),
2.07–1.99 (m, 2 H, CH2) ppm. 13C NMR (75.4 MHz, CDCl3): δ =
172.8, 146.6, 144.4, 143.9, 141.8, 138.5, 134.1, 131.7, 129.1, 127.0,
125.8, 124.2, 122.2, 39.3, 32.8, 32.5, 25.5 ppm.
2-(3,4-Dimethylbenzyl)benzoic Acid (5c): Keto acid 4c (2.0 g,
7.86 mmol), upon reduction using zinc dust (3.39 g, 51.84 mmol)
and mercuric chloride (0.33 g, 1.21 mmol) following a procedure
similar to that described for 5a gave benzyl acid 5c (1.73 g, 92%) as
a colourless solid, m.p. 108–110 °C. 1H NMR (300 MHz, CDCl3): δ
= 8.05 (d, J = 7.8 Hz, 1 H, ArH), 7.97–7.65 (m, 1 H, ArH), 7.63–
7.53 (m, 1 H, ArH), 7.45–7.43 (m, 1 H, ArH), 7.33–7.23 (m, 1 H,
ArH), 7.20–6.95 (m, 2 H, ArH), 4.39 (s, 2 H, CH2), 2.20 (s, 6 H,
CH3) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 172.9, 150.0, 143.9,
138.1, 134.3, 133.0, 131.7, 130.5, 129.6, 128.2, 126.5, 126.2, 123.0,
39.1, 19.8 ppm.
2-(2,4-Dimethylbenzyl)benzoic Acid (5d): Keto acid 4d (2 g, 2-(Thiophen-2-ylmethyl)benzoic Acid (5i): Keto acid 4i (2 g,
7.87 mmol), upon reduction using zinc dust (3.39 g, 51.84 mmol)
and mercuric chloride (0.34 g, 1.24 mmol) following a procedure
similar to that described for 5a, gave benzyl acid 5d (1.66 g, 88%)
8.62 mmol), upon reduction using zinc dust (3.72 g, 56.88 mmol)
and mercuric chloride (0.369 g, 1.35 mmol) following a procedure
similar to that described for 5a, gave benzyl acid 5i (1.65 g, 88%) as
colourless crystals, m.p. 105–106 °C (ref.[22] 105–106 °C). 1H NMR
1
as a colourless solid, m.p. 74 °C. H NMR (300 MHz, CDCl3): δ
Eur. J. Org. Chem. 2015, 5099–5114
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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