Modulating the Photophysical and Optical Properties of BODIPY
FULL PAPER
Synthesis of 2-ethyl-4,4-difluoro-1,3,8-trimethyl-4-bora-3a,4a-diaza-s-inda-
cene (1a): Compound 1a was obtained through two synthetic routes:
Method A: 2-Acetyl-4-ethyl-3,5-dimethylpyrrole (2) (455 mg, 2.8 mmol)
tion and extracted with Et
with H
over MgSO
2
O. The combined organic phases were washed
2
3
O, saturated NaHCO solution and brine. The extract was dried
4
, filtered and concentrated to dryness. Flash chromatography
in CHCl
.8 mmol) in CHCl
BF ·Et O (0.3 mL, 2.8 mmol) were reacted. Flash chromatography using
hexane/EtAcO (98:2) afforded 1a (190 mg, 26%) as a red solid and
PM567 (35 mg, 4%).
3
(20 mL), POCl
3
(0.3 mL, 3.3 mmol), pyrrole (3a) (0.2 mL,
using hexane/EtAcO (98:2) afforded 3c (212 mg, 13%) as a beige solid
and 3d (329 mg, 12%) as a slightly yellow solid.
2
3
(10 mL), triethylamine (0.4 mL, 2.8 mmol) and
1
3
2
Compound 3c: m.p. 137.6–137.98C; H NMR (200 MHz, CDCl
3
): d=8.57
(
brs, 1H, NH), 8.12 (d, J=7.6 Hz, 1H, CH), 7.72–7.65 (m, 3H, 3 CH),
7
.37 (brs, 1H, CH), 7.33–7.19 (m, 4H, 4 CH), 6.92 (brs, 1H, CH), 6.66
1
13
Compound 1a: m.p. 155.5–156.08C; H NMR (300 MHz, CDCl
3
): d=
(brs, 1H, CH), 6.34–6.32 ppm (m, 1H, CH); C NMR (125 MHz,
CDCl ): d=141.2 (C), 140.5 (C), 138.8 (C), 136.8 (C), 132.4 (C), 128.8
7
2
.47 (brs, 1H, CH), 6.93 (d, J = 3.6 Hz, 1H, CH), 6.31 (dd, J = 3.6,
.1 Hz, 1H, CH), 2.48 (s, 3H, CH ), 2.46 (s, 3H, CH ), 2.33 (q, J = 7.5
), 2.24 (s, 3H, CH ), 0.97 ppm (t, J = 7.5 Hz, 3H, CH );
C NMR (75 MHz, CDCl ): d=160.3 (C=N), 140.8 (C), 140.4 (2 C),
36.6 (CH), 135.1 (C), 134.1 (C), 122.7 (CH), 114.9 (CH), 17.0 (CH ),
6.5 (CH ), 14.5 (CH ), 14.0 (CH ), 13.1 ppm (CH ); IR (neat): n˜ =1568
3
(C), 128.5 (CH), 127.8 (CH), 127.3 (CH), 123.5 (CH), 120.8 (CH), 120.7
(CH), 120.4 (CH), 120.1 (CH), 120.0 (CH), 117.3 (CH), 114.3 (CH),
3
3
Hz, 2H, CH
2
3
3
1
3
ꢁ1
111.1 ppm (CH); IR (neat): n˜ =3460 (NH), 1580 cm (C=C); MS: m/z
3
+
1
1
2
(%): 243 (82) [M] , 242 (100), 215 (10); elemental analysis calcd (%) for
C
18
H
13N: C 88.86, H 5.39, N 5.76; found: C 88.84, H 5.38, N 5.78.
3
3
3
3
ꢁ1
+
(
(
2
C=N), 1455 cm (C=C); MS: m/z (%): 262 (38) [M] , 247 (100), 227
1
Compound 3d: m.p. 165.0–166.08C; H NMR (300 MHz, CDCl
3
): d=
+
+
16); HR-MS-ESI : calcd for (C14
63.1428.
Method B: 2-Acetylpyrrole (1 g, 9.2 mmol) in CHCl
2 2
H17BF N +H ): 263.1532; found:
7
9
.70–7.65 (m, 4H, NH, 3 CH), 7.54–7.52 (m, 2H, 2 CH), 7.34–7.09 (m,
H, 9 CH), 6.93–6.90 (m, 2H, 2 CH), 6.16–6.14 (m, 1H, CH), 5.70–5.67
(20 mL), POCl
1 mL, 10.1 mmol), 3-ethyl-2,4-dimethylpyrrole (1.13 g, 9.2 mmol) in
3
(m, 1H, CH), 5.26–5.20 (m, 1H, CH), 4.73 (d, J=7.5 Hz, 2H, 2 CH),
3
1
3
(
3
3.29 ppm (t, J=7.5 Hz, 1H, CH); C NMR (75 MHz, CDCl ): d=144.6
CHCl
3
(20 mL), triethylamine (1.3 mL, 9.2 mmol) and BF
3
·Et
2
O (1.1 mL,
(2 C), 144.2 (C), 144.0 (C), 141.7 (2 C), 141.2 (2 C), 128.3 (2 CH), 128.0
(2 CH), 127.2 (4 CH), 125.3 (4 CH), 123.3 (C), 120.5 (2 CH), 120.4 (2
CH), 120.3 (CH), 114.1 (CH), 94.9 (CH), 50.0 (2 CH), 48.2 ppm (CH);
9
.2 mmol) were allowed to react. Flash chromatography using hexane/
[
11]
EtAcO (98:2) afforded 1a (1.1 g, 46%) and traces of BODIPY 6.
ꢁ
1
+
IR (neat): n˜ =3457 (NH), 1570 cm (C=C); MS: m/z (%): 409 (1) [M] ,
Synthesis of 2-[(E)-1H-inden-1-ylidenemethyl]-1H-pyrrole (3b): To a so-
lution of indene (539 mg, 4.6 mmol) in dry THF (20 mL) at 08C and
under an argon atmosphere, was added dropwise a solution of nBuLi
2
5
44 (100), 165 (19); elemental analysis calcd (%) for C31
.66, N 3.42; found: C 90.95, H 5.64, N 3.41.
H23N: C 90.92, H
(
3.2 mL, 1.6m in hexane). The reaction mixture was stirred at RT for 1 h
Method B: To a stirred suspension of (bromomethyl)triphenylphospho-
nium bromide (4.46 g, 10.2 mmol) in THF (60 mL) under argon and at
ꢁ608C was added sodium bis(hexamethylsilyl)amide (6 mL, 2.0m in
THF). The resulting red solution was stirred at ꢁ608C for 40 min, and
then a solution of fluorenone (1.66 g, 9.2 mmol) in THF (10 mL) was
added. It was allowed to warm slowly to RT and stirred overnight before
and then, a solution of 11 (1 g, 5.1 mmol) in dry THF (20 mL) was
added. The mixture was refluxed for 4 h to complete the reaction and al-
lowed to warm at RT before being quenched with saturated NH
tion and extracted with Et O. The combined organic phases were washed
with H O, saturated NaHCO solution and brine. The extract was dried
over MgSO , filtered and concentrated to dryness. Flash chromatography
using hexane/EtAcO (98:2) afforded 3b (145 mg, 16%) as a yellow solid:
m.p. 128.7–129.08C; H NMR (300 MHz, CDCl
7
6
4
Cl solu-
2
2
3
being quenched with H
dried over MgSO , filtered and concentrated to dryness. Flash chroma-
tography using hexane afforded 16
2 2
O and extracted with Et O. The extract was
4
4
1
[12]
): d=8.44 (brs, 1H, NH),
.56–7.53 (m, 1H, CH), 7.27–7.24 (m, 1H, CH), 7.17–7.09 (m, 3H, 3 CH),
.92–6.89 (m, 3H, 3 CH), 6.60 (brs, 1H, CH), 6.28–6.27 ppm (m, 1H,
(2.27 g, 96%) as a yellow solid.
3
H NMR (200 MHz, CDCl ): d=8.58 (d, J=7.8 Hz, 1H, CH), 7.72 (d, J=
3
1
7.8 Hz, 1H, CH), 7.68 (d, J=7.8 Hz, 1H, CH), 7.57 (d, J=7.8 Hz, 1H,
CH), 7.45 (dt, J=7.7, 1.4 Hz, 1H, CH), 7.40 (s, 1H, CH), 7.39–7.34 (m,
2H), 7.28 ppm (dt, J=7.8, 0.8 Hz, 1H, CH).
1
3
CH); C NMR (50 MHz, CDCl
1
1
3
): d=141.4 (C), 137.9 (C), 133.8 (C),
32.8 (CH), 130.3 (C), 126.6 (CH), 125.2 (CH), 124.9 (CH), 122.4 (CH),
21.2 (CH), 118.7 (CH), 118.3 (CH), 114.9 (CH), 111.4 ppm (CH); IR
To a solution of 16 (601 mg, 2.3 mmol) in DME (30 mL) under an argon
atmosphere, were added 15 (494 mg, 2.3 mmol) and Na CO (297 mg,
ꢁ1
+
(
neat): n˜ =3457 (NH), 1640 cm (C=C); MS: m/z (%): 193 (87) [M] ,
2
3
1
8
92 (100), 165 (19), 95 (11); elemental analysis calcd (%) for C14
7.01, H 5.74, N 7.25; found: C 87.03, H 5.71, N 7.26.
H
11N: C
2.8 mmol) in the presence of a catalytic amount of tetrakis(triphenyl-
phosphine)palladium (8.6 mg, 0.008 mmol). The reaction mixture was re-
fluxed for 38 h to complete the reaction and allowed to warm at RT
Synthesis of 2-ethyl-4,4-difluoro-5-indenylidene-1,3,8-trimethyl-4-bora-
a,4a-diaza-s-indacene (1b): 2-Acetyl-4-ethyl-3,5-dimethylpyrrole (2)
115 mg, 0.7 mmol) in CHCl (10 mL), POCl (0.07 mL, 0.8 mmol), pyr-
role 3b (140 mg, 0.7 mmol) in CHCl (10 mL), triethylamine (0.1 mL,
.7 mmol) and BF ·Et O (0.09 mL, 0.7 mmol) were allowed to react.
Flash chromatography using hexane/EtAcO (98:2) afforded 1b (114 mg,
3
(
before being quenched with H
was dried over MgSO , filtered and concentrated to dryness. Flash chro-
matography using hexane/Et O (99:1) afforded 3c (74 mg, 13%).
2 2 2
O and extracted with CH Cl . The extract
3
3
4
3
2
0
3
2
Synthesis of 2-ethyl-4,4-difluoro-5-fluorenylidene-1,3,8-trimethyl-4-bora-
3a,4a-diaza-s-indacene (1c): 2-Acetyl-4-ethyl-3,5-dimethylpyrrole (2)
(65 mg, 0.4 mmol) in CHCl (10 mL), POCl (0.04 mL, 1.1 mmol), pyrrole
1
4
7
7
2%) as a blue solid: m.p. 286–2878C; H NMR (300 MHz, CDCl
.80 (brs, 1H, CH), 7.71–7.68 (m, 1H, CH), 7.21–7.11 (m, 3H, 3 CH),
.02–6.85 (m, 4H, 4 CH), 2.55 (s, 3H, CH ), 2.49 (s, 3H, CH ), 2.36 (q,
), 2.28 (s, 3H, CH ), 1.01 ppm (t, J=7.5 Hz, 3H,
); C NMR (75 MHz, CDCl ): d=160.4 (C=N), 147.3 (C), 141.9
CH), 141.6 (2 C), 138.0 (C), 137.8 (CH), 136.2 (C), 135.0 (CH), 127.6
CH), 125.9 (CH), 125.4 (CH), 123.6 (2 C), 121.1 (CH), 120.1 (CH), 119.0
2 C), 118.4 (CH), 17.1 (CH ), 16.4 (CH ), 14.5 (CH ), 14.0 (CH ),
3.2 ppm (CH ); IR (neat): n˜ =1565 (C=N), 1440 cm ; MS: m/z (%): 388
3
): d=
3
3
3c (97 mg, 0.4 mmol) in CHCl3 (10 mL), triethylamine (0.06 mL,
3
3
0.4 mmol) and BF ·Et O (0.05 mL, 0.4 mmol) were allowed to react.
3
2
J=7.5 Hz, 2H, CH
CH
(
(
(
2
3
Flash chromatography using hexane/EtAcO (98:2) afforded 1c (26 mg,
1
3
1
3
3
15%) as a blue solid: m.p. 277–2788C; H NMR (200 MHz, CDCl ): d=
3
8.20 (d, J=7.7 Hz, 1H, CH), 7.87 (brs, 1H, CH), 7.81–7.78 (m, 1H, CH),
7.65–7.58 (m, 2H, 2 CH), 7.26–7.03 (m, 6H, 6 CH), 2.53 (s, 3H, CH ),
3
2
3
3
3
2.52 (s, 3H, CH ), 2.35 (q, J=7.5 Hz, 2H, CH ), 2.28 (s, 3H, CH ),
3
2
3
ꢁ
1
13
1
3
3 3
1.00 ppm (t, J=7.5 Hz, 3H, CH ); C NMR (50 MHz, CDCl ): d=160.3
+
+
+
(
3
100) [M] , 373 (59); HR-MS-ESI : calcd for (C24
89.2001; found: 389.1997.
Synthesis of 2-[1H-fluoren-1-ylidenemethyl]-1H-pyrrole (3c): Compound
c was obtained through two synthetic routes. Method A: To a solution
H
23BF
2
N
2
+H ):
(C=N), 146.4 (C), 141.5 (C), 140.3 (C), 140.0 (C), 138.8 (C), 138.2 (C),
138.0 (C), 136.3 (C), 136.0 (C), 135.5 (C), 134.6 (C), 128.8 (CH), 128.4
(
CH), 127.1 (CH), 126.7 (CH), 125.0 (CH), 122.7 (CH), 121.0 (CH),
19.8 (CH), 119.5 (CH), 119.1 (CH), 117.4 (CH), 17.0 (CH ), 16.3 (CH ),
4.5 (CH ), 13.9 (CH ), 13.1 ppm (CH ); IR (neat): n˜ =1568 (C=N),
1
1
1
5
4
2
3
3
of fluorene (1.11 g, 6.7 mmol) in dry THF (40 mL) at 08C and under an
argon atmosphere, was added dropwise a solution of nBuLi (1.6m in
hexane) (4.8 mL, 7.6 mmol). The reaction mixture was stirred at RT for
3
1
3
3
ꢁ
+
447 cm (C=C); MS: m/z (%): 438 (3) [M] , 322 (13), 85 (51), 71(67),
+
+
7 (100); HR-MS-ESI : calcd for (C28
H
25BF
2
N
2
+H ): 439.2158; found:
39.2154.
1
h and then, a solution of 11 (1.44 g, 7.4 mmol) in dry THF (20 mL) was
added. The mixture was refluxed for 4 h to complete the reaction and al-
lowed to warm at RT before being quenched with saturated NH Cl solu-
Synthesis of 2-ethyl-4,4-difluoro-5-(di-9H-fluoren-9-ylmetyl)-1,3,8-tri-
methyl-4-bora-3a,4a-diaza-s-indacene (1d): 2-Acetyl-4-ethyl-3,5-dimethyl-
4
Chem. Eur. J. 2010, 16, 14094 – 14105
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
14103