PAPER
Regiospecific Synthesis of Substituted Nitrofluorenes and Aminofluorenes
1249
Chromatography (cyclohexane/CH2Cl2, 2:1) afforded 1a; yield:
MS (70eV): m/z (%) = 279 (M+, 92), 262 (M+, 42), 249 (M+ – NO,
0.597 g (76%); mp 180–182°C (Lit.6 mp 180–181°C)
18), 233 (M+ – NO2, 100).
1H NMR (CDCl3, 300 MHz) d = 2.45 (s, 3 H, CH3), 3.93 (s, 2 H,
CH2), 7.27 (d, 1 H, 3J = 7.8 Hz, Harom), 7.41 (Ys, 1 H, Harom), 7.73
(d, 1 H, 3J = 7.8 Hz, Harom), 7.79 (d, 1 H, 3J = 8.4 Hz, Harom), 8.26
(dd, 1 H, 3J = 8.4 Hz, 4J = 2.1 Hz, Harom), 8.35 (Ys, 1 H, Harom).
HRMS (70eV): m/z calc. for C14H8NO2F3 279.0508, found
279.0503.
2-Amino-7-methylfluorene (2a); Typical Procedure
13C NMR (CDCl3, 100 MHz) d = 21.8, 36.8, 119.4, 120.4, 121.1,
A mixture of 1a (0.420 g, 1.86 mmol) and SnCl2•2H2O (2.10 g,
9.32 mmol) in EtOH (15 mL) and EtOAc (15 mL) was heated to
70°C under argon until the starting material had disappeared
according to TLC (up to 10 h). The cooled solution was poured onto
ice and the pH was made slightly basic by addition of NaHCO3 so-
lution to form SnO2 (aq). After extraction with EtOAc the organic
layer was thoroughly washed with H2O and brine,19 dried (MgSO4)
and evaporated to dryness in vacuo. Chromatography (PE/EA, 2:1)
afforded 2a; yield: 0.348 g (96%); mp 106–107°C (Lit.6 105–
106°C).
123.1, 126.1, 128.4, 136.9, 139.2, 143.7, 145.2, 146.4, 148.2.
MS (70eV): m/z (%) = 225 (M+, 95), 179 (M+ – NO2, 98) 178 (179
– H, 100).
HRMS (70eV): m/z calc. for C14H11NO2 225.0790, found
225.0796.
7-tert-Butyl-2-nitrofluorene (1b)
Reaction of 7b (0.623 g, 2.18 mmol) with PPA (3.7 g) in MeSO3H
(12 mL) and CHCl3 (40 mL) gave after workup and chromatogra-
phy (cyclohexane/CH2Cl2, 2:1) 1b; yield: 0.420 g (72%); mp 189–
191°C (subl.).
1H NMR (CD2Cl2; 300 MHz) d = 2.40 (s, 3 H, CH3), 3.75 (s, 2 H,
CH2), 3.71–3.79 (br s, 2 H, NH2 ), 6.67 (dd, 1 H, 3J = 8.1 Hz, 4J =
3
2.1 Hz, Harom), 6.84 (Ys, 1 H, Harom), 7.13 (Yd, 1 H, J = 7.7 Hz,
Harom), 7.30 (Ys, 1 H, Harom), 7.51 (d, 1 H, 3J = 8.1 Hz, Harom), 7.52
(d, 1 H, 3J = 7.7 Hz, Harom).
1H NMR (CDCl3; 300 MHz) d = 1.37 (s, 9 H, t-C4H9), 3.96 (s, 2 H,
CH2), 7.49 (dd, 1 H, 3J = 8.1 Hz, 4J = 1.7 Hz, Harom), 7.64 (Ys, 1 H,
arom), 7.77 (d, 1 H, 3J = 8.1 Hz, Harom), 7.81 (d, 1 H, 3J = 8.4 Hz,
13C NMR (CD2Cl2; 75 MHz) d = 21.7, 37.1, 112.1, 114.1, 118.6,
120.6, 126.0, 127.8, 133.2, 135.3, 140.0, 143.1, 145.6, 146.4.
MS (70eV): m/z (%) = 195 (M+, 100), 180 (M+ – CH3, 47), 165 (M+
– NH, 12), 152 (13).
H
Harom), 8.26 (dd, 1 H, 3J = 8.4 Hz, 4J = 2.2 Hz, Harom), 8.36 (Ys, 1 H,
arom).
H
13C NMR (CDCl3; 75 MHz) d = 31.5, 35.1, 37.0, 119.5, 120.4,
120.9, 122.3, 123.1, 124.8, 136.9, 144.0, 144.9, 146.5, 148.2, 152.6.
MS (70eV): m/z (%) = 267 (M+, 28), 252 (M+ – CH3, 100), 206 (252
HRMS (70eV): m/z calc. for C14H13N 315.1048, found 195.1042.
– NO2, 15).
2-Amino-7-tert-butylfluorene (2b)
Compound 1b (0.400 g, 1.50 mmol) was reduced with SnCl2•2H2O
(1.70 g, 7.19 mmol) in EtOH (20 mL) and EtOAc (20 mL). Workup
and chromatography (CHCl3) afforded 2b; yield: 0.327 g (92%);
mp 155–157°C (subl.).
HRMS (70eV): m/z calc. for C16H17NO2 267.1259, found
267.1258.
7-(1-Adamantyl)-2-nitrofluorene (1c)
1H NMR (CDCl3; 300 MHz) d = 1.35 (s, 9 H, t-C4H9), 3.40–3.90 (br
s, 2 H, NH2), 3.78 (s, 2 H, CH2), 6.67 (dd, 1 H, 3J = 8.1 Hz, 4J = 2.2
Hz, Harom), 6.85 (Ys, 1 H, Harom), 7.34 (Yd, 1 H, 3J = 8.1 Hz, Harom),
7.50 (Ys, 1 H, Harom), 7.51 (d, 1 H, 3J = 8.1 Hz, Harom), 7.55 (d, 1 H,
Compound 7c (0.974 g, 2.68 mmol) was reacted with PPA (4.6 g)
in MeSO3H (14 mL) and CHCl3 (40 mL). Workup and chromato-
graphy (cyclohexane/CH2Cl2, 2:1) afforded 1c; yield: 0.638 g
(69%); mp >230°C.
1H NMR (CDCl3, 300 MHz) d = 1.79 (m, 6 H, adamantyl), 1.96 (m,
6 H, adamantyl), 2.12 (m, 3 H, adamantyl), 3.96 (s, 2 H, CH2), 7.46
(Yd, 1 H, 3J = 8.6 Hz, Harom), 7.61 (Ys, 1 H, Harom), 7.79 (d, 1 H, 3J
= 8.2 Hz, Harom), 7.80 (d, 1 H, 3J = 8.4 Hz, Harom), 8.26 (dd, 1 H, 3J
= 8.4 Hz, 4J = 2.1 Hz, Harom), 8.36 (Ys, 1 H, Harom).
13C NMR (CDCl3; 100 MHz) d = 26.9, 28.9, 36.7, 37.0, 43.3, 119.5,
120.4, 120.9, 121.9, 123.2, 124.4, 137.0, 144.0, 145.0, 146.4, 148.3,
152.9.
MS (70eV): m/z (%) = 345 (M+, 100), 288 (M+ – C4H9, 38) 251
(21), 242 (288 – NO2, 48) 135 (33).
3J = 8.1 Hz, Harom
)
13C NMR (CDCl3; 75 MHz) d = 31.6, 34.7, 36.9, 111.9, 113.9,
118.1, 120.3, 121.7, 123.7, 133.1, 139.5, 142.2, 145.2, 145.3, 148.3.
MS (70eV): m/z (%) = 237 (M+, 89), 222 (M+ – CH3, 100), 193 (M+
– C2H5, 22), 180 (M+ – C4H9, 33).
HRMS (70eV): m/z calc. for C17H19N 237.1517, found 237.1515.
7-(1-Adamantyl)- 2-aminofluorene (2c)
Compound 1c (0.300 g, 0.868 mmol) was reduced with SnCl2•2H2O
(0.980 g, 4.32 mmol) in EtOH (30 mL) and EtOAc (30 mL). Work-
up and chromatography (PE/EA, 5:2) afforded 2c; yield: 0.246 g
(90%); mp 228–230°C.
HRMS (70eV): m/z calc. for C23H23NO2 345.1729, found
345.1728.
1H NMR (CDCl3; 300 MHz) d = 1.77 (m, 6 H, adamantyl), 1.95 (m,
6 H, adamantyl), 2.09 (m, 3 H, adamantyl), 3.77 (s, 2 H, CH2), 3.70–
3.79 (br s, 2 H, NH2), 6.67 (dd, 1 H, 3J = 8.1 Hz, 4J = 2.1 Hz, Harom),
6.85 (Ys, 1 H, Harom), 7.31 (Yd, 1 H, 3J = 8.0 Hz, Harom), 7.47 (Ys,
1 H, Harom), 7.50 (d, 1 H, 3J = 8.1 Hz, Harom), 7.55 (d, 1 H, 3J = 8.0
Hz, Harom).
13C NMR (CDCl3; 75 MHz) d = 29.2, 36.4, 37.020, 43.6, 112.0,
114.0, 118.2, 120.5, 121.4, 123.4, 136.6, 139.7, 142.3, 145.420,
148.8.
2-Nitro-7-trifluoromethylfluorene (1d)
Compound 7d (1.00 g, 3.36 mmol) was dissolved in CHCl3 (5 mL)
and PPA (11.0 g) was added. The mixture was heated to 80°C under
argon for 16 h. Workup and chromatography (cyclohexane/CH2Cl2,
3:1) afforded 1d; yield: 0.431g (46%); mp 180–182°C (subl.).
1H NMR (CDCl3, 400 MHz) d = 4.1 (s, 2 H, CH2), 7.71 (Yd, 1 H,
3J = 8.6 Hz, Harom), 7.86 (Ys, 1 H, Harom), 7.92 (d, 1 H, 3J = 8.8 Hz,
H
arom), 7.95 (d, 1 H, 3J = 8.8 Hz, Harom), 8.32 (dd, 1 H, 3J = 8.8 Hz,
4J = 1.8 Hz, Harom), 8.43 (Ys, 1 H, Harom).
MS (70eV): m/z (%) = 315 (M+, 100), 262 (13), 258 (M+ – C4H9,
29).
13C NMR (CDCl3; 100 MHz) d = 37.0, 120.6, 120.8, 121.5, 122.3,
3
1
123.3 [q J(CF) = 3.8 Hz], 124.2 [q J(CF) = 272.4 Hz], 124.7 [q
3J(CF) = 3.7 Hz], 130.6 [q 2J(CF) = 32.3 Hz], 142.7, 144.5, 144.9,
146.3, 147.6.
HRMS (70eV) m/z calc. for C23H25N 315.1987, found 315.1992.
Synthesis 1999, No. 7, 1246–1250 ISSN 0039-7881 © Thieme Stuttgart · New York