the chirality center is not found at the amine substituent
but at the fluorene ring.
was mixed with AcOEt (50 mL) and washed with brine (100 mL).
The organic layer was dried over MgSO , filtered, and concen-
trated. The crude product was purified by column chromatog-
raphy on silica gel with AcOEt/hexanes ) 1:5) affording the
products as crystalline or glassy material.
4
In summary, Pd-catalyzed substitution of 2-halo-9,9-
dialkylfluorenes gives straightforward access to donor-
acceptor-substituted fluorenes whose polarity and solu-
bility can easily be tuned by the length of the alkyl
substituents at the amino group and at position 9.
Optically active fluorenes are also accessible in this way.
Long lipophilic substituents can be expected to serve as
anchors to fix such fluorenes in membranes, micelles, and
vesicles, allowing femtosecond dynamic polarity mea-
surements in close proximity of such supramolecular
assemblies. Detailed physicochemical investigations of
these products are currently underway. Preliminary
femtosecond measurements with 2-(dimethylamino)-7-
nitrofluorene show that N-alkylated aminofluorenes should
be better probes of solvation dynamics than the parent
2
-Dibu tylam in o-7-n itr o-9,9-di(n -pr opyl)-9H-flu or en e (9a).
The dark red product 9a was obtained in 74% yield starting from
iodo compound 7a and in 73% starting from bromo compound
7
1
1
6
8
b: 1H NMR (CDCl
3
) δ 0.69 (m, 10H). 0.98 (t, J ) 7.2 Hz, 6H),
.36 (t, J ) 7.2 Hz, 2H), 1.43 (t, J ) 7.5 Hz, 2H), 1.62 (m, 4H),
.93 (m, 4H), 3.36 (t, J ) 7.5 Hz, 4H), 6.56 (d, J ) 2.3 Hz, 1H),
.65 (d, J ) 8.3 Hz, 1H), 7.52 (d, J ) 8.3 Hz, 1H), 7.56 (d, J )
.3 Hz, 1H), 8.11 (d, J ) 2.3 Hz, 1H), 8.18 (d, J )8.3 Hz, 1H);
1
13C NMR (CDCl ) δ 14.0 (CH ), 14.4 (CH ), 17.1 (CH ), 20.4
3
3
3
2
(CH
2
), 29.4 (CH
2
), 42.7 (CH
2
2
), 51.0 (CH ), 55.3 (C), 105.4 (CH),
1
11.1 (CH), 117.3 (CH), 117.9 (CH), 122.3 (CH), 123.7 (CH), 126.3
(
C), 144.8 (C), 149.0 (C), 149.6 (C), 150.4 (C), 154.6 (C); MS (CI)
+
m/z 422 (M , 59), 379 (100). Anal. Calcd for C27
6.74; H, 9.06; N, 6.63. Found: C, 77.10; H, 9.06; N, 6.52.
,9-Dim eth yl-2-m or p h olin o-7-n itr o-9H-flu or en e (9b). The
dark red product 9b was obtained in 43% yield starting from
38 2 2
H N O : C,
7
9
2
-amino-7-nitrofluorene, mainly by virtue of a larger
1
7
1
Stokes shift.
the bromo compound 7c: mp 120-125 °C; H NMR (CDCl
1
4
8.3 Hz, 1H, CH), 7.66 (d, J ) 6.8 Hz, 1H, CH), 7.66 (t, 1H, J )
8
3
) δ
), 3.90 (t, J )
), 6.96 (dd, J ) 6.8 Hz, 1H, CH), 6.94 (dd, J )
.51 (s, 6H, CH), 3.29 (t, J ) 4.89 Hz, 4H, CH
2
.89 Hz, 4H, CH
2
Exp er im en ta l Section
13
.3 Hz, CH), 8.22 (dd, 2H, J ) 6.8 Hz, CH); C NMR (CDCl
3
) δ
7
-Nitr o-9H-flu or en -2-yla m in e (2). A mixture of 2,7-dini-
26.99 (CH ), 47.20 (C), 49.01 (CH ), 66.79 (CH ), 109.24 (CH),
3
2
2
trofluorene (4 g, 0.015 mol), 10% palladium on carbon (0.25 g),
and triethylamine (20 mL, 0.14 mol) was placed in a two-necked
round-bottomed flask which was equipped with a reflux con-
denser. The mixture was heated to boiling, and formic acid (3.06
g, 2.56 mL, 0.067 mol) was added dropwise with stirring. The
mixture was boiled for about 30-40 min. The reaction mixture
turned a dark reddish color a few minutes after addition of
formic acid. After, the reaction mixture was cooled, dichlo-
romethane was added and the catalyst was removed by filtration.
The solvent and excess triethylamine were removed under
reduced pressure, and the reddish residue was chromatographed
114.75 (CH), 118.10 (CH), 118.76 (CH), 122.39 (CH), 123.65
(CH), 128.62 (C), 146.00 (C), 146.13 (C), 152.69 (C), 153.90 (C),
156.98 (C). Anal. Calcd for C19
20 2 3
H N O : C, 70.35; H, 6.21; N,
8.64; O, 14.80. Found: C, 70.16; H, 6.26; N, 8.37.
9,9-Dim eth yl-7-n itr o-2-p ip er id in o-9H-flu or en e (9c). The
dark red product 9c was obtained in 41% yield starting from
1
the bromo compound 7c: mp 136-139 °C; H NMR (CDCl
3
) δ
), 3.30 (t,
), 6.97 (m, 2H, CH), 7.62 (q, 2H, CH), 8.2
1.49 (s, 6H, CH
3 2 2
), 1.64 (m, 2H CH ), 1.74 (m, 4H, CH
J ) 5.25 Hz, 4H, CH
2
1
3
(dd, J ) 7.1 Hz, CH); C NMR (CDCl
3
) δ 24.3 (CH
), 109.6 (CH), 115.2 (CH), 118.0
2 2
), 25.7 (CH ),
27.0 (CH
3
), 47.1 (C), 50.2 (CH
2
on silica gel with dichloromethane to give a bright red solid of
1
(CH), 118.4 (CH), 122.3 (CH), 123.7 (CH), 127.4 (C), 145.7 (C),
146.5 (C), 153.4 (C), 153.8 (C), 157. (C); MS (CI) m/ z 322 (M ,
.94 g (57% yield): mp 228-230 °C (lit.18 mp 232 °C); H NMR
1
+
(
6
8
DMSO-d
6
) δ 3.93 (s, 2H), 5.74 (s, 2H), 6.71 (d, J ) 7.9 Hz, 1H),
62), 224 (100). Anal. Calcd for C20
22 2 2
H N O : C, 74.51; H, 6.88;
.85 (s, 1H), 7.74 (d, J ) 8.3 Hz, 1H), 7.82 (d, J ) 8.7 Hz, 1H),
.23 (d, J ) 7.9 Hz, 1H), 8.31 (s, 1H). Anal. Calcd for
N, 8.69. Found: C, 73.84; H, 6.66; N, 8.43.
2-[(2S)-2-(Meth oxym eth yl)-1-p yr r olid in o]-7-n itr o-9,9-d i-
(n -p r op yl)-9H-flu or en e (9d ). The deeply orange product 9d
13 10 2 2
C H N O : C, 69.02; H, 4.46; N, 12.38. Found: C, 69.04; H,
4
.32; N, 12.09.
was obtained in 56% yield starting from the bromo compound
7b: mp 51-53 °C; [R]21
) -131 (c 0.1, CH
) δ 0.68 (m, 10H, CH, CH ), 1.99 (m, 8H, CH
2H, J ) 8.3 Hz, CH ), 3.30 (s, 3H, CH ), 3.53 (m, 2H, CH
Cl
); H NMR
1
N,N-Dim eth yl-(7-n itr o-9H-flu or en -2-yl)a m in e (3). To the
D
2
2
stirred mixture of 7-nitro-9H-fluoren-2-ylamine (100 mg, 0.442
mmol) and paraformaldehyde (148 mg, 0.005 mmol) in 99%
glacial acetic acid (4 mL) at 25 °C under argon was added
(CDCl
3
3
2
), 3.27 (t,
), 4.00
2
3
2
(d, 1H, J ) 3.8 Hz, CH), 6.59 (d, 1H, J ) 1.9 Hz, CH), 6.67 (dd,
1H, J ) 8.3 Hz, CH), 7.54 (d, J ) 8.3 Hz, 1H, CH), 7.59 (d, 1H,
J ) 8.3 Hz, CH), 8.11 (d, 1H, J ) 2.3 Hz, CH), 8.19 (dd, 1H, J
3
NaCNBH (140 mg, 2.25 mmol) in one portion. The resulting
mixture was stirred at 25 °C for 24 h and then poured into cold
water. A bright orange-red solid precipitated. It was filtered off
1
3
) 8.3 Hz, CH); C NMR (CDCl
(CH ), 23.2 (CH ), 28.9 (CH ), 42.7 (CH
58.4 (CH ), 59.2 (CH), 73.0 (CH ), 106.0 (CH), 11.6 (CH), 117.4
3
) δ 14.4 (CH
3
), 17.1 (CH
2
), 17.1
and recrystallized from MeCN/water: yield 91 mg (81%); 1
H
), 48.7 (CH
), 55.4 (C),
2
2
2
2
2
NMR (CDCl
J
1
1
3
) δ 3.05 (s, 6H), 3.88 (s, 2H), 6.75 (dd, J
) 2.2 Hz, 1H), 6.89 (d, J ) 1.9 Hz, 1H), 7.61 (d, J ) 8.7 Hz,
H), 7.67 (d, J ) 8.7 Hz, 1H), 8.22 (d, J ) 8.7 Hz, 1H), 8.26 (s,
1
) 2.6 Hz,
3
2
2
(CH), 117.9 (CH), 122.3 (CH), 123.7 (CH), 127.2 (C), 145.1 (C),
148.8 (C), 148.9 (C), 150.5 (C), 1547 (C); HRMS calcd for
1
3
H); C NMR (CDCl
3
) δ 36.9 (CH
2
), 40.6 (CH
3
), 108.2 (CH), 111.7
C
25
H
32
N
2
O
2
408.24129, found 408.24124.
(
1
CH), 117.7 (CH), 120.1 (CH), 122.2 (CH), 123.5 (CH), 128.1 (C),
42.2 (C), 144.2 (C), 147.2 (C), 149.2 (C), 151.4 (C). Anal. Calcd
for C15 : C, 70.85; H, 5.55; N, 11.02. Found: C, 70.36;
H, 5.85; N, 10.70.
-Am in o-9,9-d ia lk ylflu or en es 9 a n d 10: Gen er a l P r oce-
d u r e. To a solution of 2-bromo- or 2-iodo-9,9-dialkyl-9H-fluorene
(2 mmol) or 2-iodo-9-(n-butyl)-9-methyl-7-nitro-9H-fluorene (2
mmol), the corresponding amine 8 (4 mmol), and NaO-t-Bu (520
mg, 5 mmol) in dry toluene (16 mL) were added Pd(OAc) (26
7-Nitr o-2-[(R)-1-p h en yleth yla m in o]-9,9-d ip r op yl-9H-flu -
or en e (9e). The red product 9e was obtained in 75% yield
1
H
14
N
2
O
2
starting from the bromo compound 7b: mp 49-51 °C; H NMR
(CDCl ) δ 0.43 (m, 2H) 0.52 (m, 3H), 0,67 (m, 5H), 1.59 (t, 3H,
3
2
3 2 2
J ) 6.8 Hz, CH ), 1.64 (m, 1H, CH ), 1.84 (m, 3H, CH ), 4.42 (s,
1H, CH), 4.61 (q, 1H, J ) 6.8 Hz, CH), 6.41 (d, 1H, J ) 1.9 Hz,
CH), 6.55 (dd, 1H, J ) 8.3 Hz, CH), 7.22 (m, 1H, J ) 6.8 Hz,
CH), 7.30 (d, 1H, J ) 7.9 Hz, CH), 7.33 (d, 2H, J ) 6.9 Hz, CH),
7.36 (d, 1H, J ) 6.4 Hz, CH), 7.48 (t, 2H, CH), 8.06 (d, 1H, J )
7
2
1
3
mg, 1 mmol) and tri-tert-butylphosphine (80 mg, 0.4 mmol) under
argon atmosphere. The solution was heated to 100 °C under inert
conditions for 15 h (6h for 9a ), during which time the color
changed to reddish brown. After being cooled to rt, the mixture
1.9 Hz, CH), 8.15 (dd, 1H, J ) 8.3 Hz, CH); C NMR (CDCl
14.2 (CH ), 14.4 (CH ), 16.9 (CH ), 17.1 (CH ), 24.8 (CH ), 42.4
(CH ), 42.5 (CH ), 53.5 (CH), 55.2 (C), 107.6 (CH), 113.1 (CH),
117.6 (CH), 117.9 (CH), 122.2 (CH), 123.6 (CH), 125.8 (CH), 127.0
3
) δ
3
3
2
2
3
2
2
(
CH), 128.7 (CH), 128.3 (C), 144.4 (C), 145.3 (C), 148.6 (C), 150.6
C), 154.4 (C). HRMS calcd for C27 414.23073, found
: C, 78.23; H, 7.29; N,
6.76. Found: C, 77.80; H, 7.49; N, 6.55.
(
30 2 2
H N O
H N O
30 2 2
(
17) Saroja, G.; Lustres, L.; Ernsting, N. P.; Liebscher, J . Manuscript
in preparation.
18) Fletcher, T. L.; Namkung, M. J . J . Org. Chem. 1960, 25, 740.
414.23069. Anal. Calcd for C27
(
J . Org. Chem, Vol. 69, No. 3, 2004 989