L. Wang et al. / Dyes and Pigments 112 (2015) 274e279
275
2,6-Dibromo-4,4-difluoro-8-(4-chlorophenyl)-1,3,5,7-tetram
ethyl-4-bora-3a,4a-diaza-s-indacene (2c): red solid; m.p.
208e210 ꢀC (212e214 ꢀC) [18]; 1H NMR (500 MHz, CDCl3):
d
¼ 1.41
(s, 6H, CH3), 2.61 (s, 6H, CH3), 7.21e7.23 (d, J ¼ 10.0 Hz, 2H, ArH),
7.52e7.54 (d, J ¼ 10.0 Hz, 2H, ArH). 13C NMR (125 MHz, CDCl3):
d
¼ 154.4, 140.4, 140.3, 135.9, 132.8, 130.3, 129.8, 129.4, 128.6, 112.1,
13.9, 13.7.
2,6-Dibromo-4,4-difluoro-8-(4-nitrophenyl)-1,3,5,7-tetrame
thyl-4-bora-3a,4a-diaza-s-indacene (2d): red solid; m.p. > 250 ꢀC
(>300 ꢀC) [18]; 1H NMR (500 MHz, CDCl3):
¼ 1.38 (s, 6H, CH3),
d
2.64 (s, 6H, CH3), 7.55 (d, J ¼ 8.6 Hz, 2H, ArH), 8.44 (d, J ¼ 8.6 Hz, 2H,
Fig. 1. 3,5- and 2,6-dihalogenated BODIPYs.
ArH). 13C NMR (125 MHz, CDCl3):
138.6, 129.6, 124.6, 112.5, 14.0, 13.8.
d
¼ 155.3, 148.7, 141.2, 140.0,
NMR experiments are reported in
and were referenced to CDCl3
d
units, parts per million (ppm),
2,6-Dibromo-4,4-difluoro-8-(3,5-dinitrophenyl)-1,3,5,7-tetra
(d
7.26 or 77.0 ppm) as the internal
methyl-4-bora-3a,4a-diaza-s-indacene
(2e):
red
solid;
standard. The coupling constants J are given in Hz. Melting points
(m.p.) are determined with a MPA 100 apparatus and are not cor-
rected. Mass spectra (EI) were measured with Jeol JMS-DX300 and
Thermo Fisher LCQ instruments. Elemental analyses were obtained
using a PerkineElmer EA2400II analyzer.
m.p. > 250 ꢀC; 1H NMR (500 MHz, CDCl3):
d
¼ 1.37 (s, 6H, CH3), 2.64
(s, 6H, CH3), 8.56 (s, 2H, ArH), 9.23 (s, 1H, ArH). 13C NMR (125 MHz,
CDCl3):
15.4, 14.8. EI-MS: m/z
19H15BBr2F2N4O4: C, 39.90; H, 2.64; N, 9.80. Found: C, 39.87; H,
2.70; N, 9.76.
d
¼ 158.0, 149.0, 141.8, 138.8, 134.5, 130.7, 129.2, 122.6, 119.4,
¼
572 [M]þ. Anal. Calcd for
C
2.2. Preparation of ChCl/HFIP
2,6-Dibromo-4,4-difluoro-1,3,5,7-tetramethyl-8-methyl-4-
bora-3a,4a-diaza-s-indacene (2f): red solid; m.p. 221e223 ꢀC; 1H
Choline chloride (139.6 g, 100 mmol) and 1,1,1,3,3,3-hexafluoro-
2-propanol (25.2 g, 150 mmol) were placed in a round bottom flask
and stirred at 50 ꢀC. After 3 h, a homogenous colorless liquid
formed, which was used directly for the reactions without
purification.
NMR (500 MHz, CDCl3):
(s, 3H, CH3). 13C NMR (125 MHz, CDCl3):
17.4, 16.4, 13.6. EI-MS: m/z
420 [M]þ. Anal. Calcd for
14H15BBr2F2N2: C, 40.05; H, 3.60; N, 6.67. Found: C, 40.11; H, 3.52;
N, 6.70.
d
¼ 2.44 (s, 6H, CH3), 2.57 (s, 6H, CH3), 2.62
d
¼ 152.2, 141.9, 138.4, 29.7,
¼
C
2,6-Diiodo-4,4-difluoro-1,3,5,7-tetramethyl-8-pentyl-4-bor
a-3a,4a-diaza-s-indacene (2g): red solid; m.p. 216e218 ꢀC; 1H
2.3. General procedures for halogenation of BODIPYs
NMR (500 MHz, CDCl3):
2.44 (s, 6H, CH3), 2.57 (s, 6H, CH3). 13C NMR (125 MHz, CDCl3):
¼ 152.3, 147.3, 137.7, 130.5, 112.0, 32.5, 31.5, 29.0, 22.5, 15.5,
14.0, 13.7. EI-MS: m/z
476 [M]þ. Anal. Calcd for
18H23BBr2F2N2: C, 45.42; H, 4.87; N, 5.89. Found: C, 45.40; H,
4.91; N, 5.87.
d
¼ 0.93 (t, 3H, CH3), 1.36e1.66 (m, 8H),
A mixture of the BODIPY 1 (0.2 mmol) and either NBS or NIS
(0.48 mmol) in ChCl/HFIP (2 mL) was stirred at room temperature
for a certain time (usually < 30 min) according to the TLC (EtOAc/
petroleum, 1:5). After reaction, the mixture was extracted with
CH2Cl2, washed with H2O, dried over Na2SO4, and concentrated
under reduced pressure. The crude product was further purified
using column chromatography (EtOAc/petroleum ether or CH2Cl2/
hexane) to afford either the bromo-products 2 or the iodo-products
3. The ChCl/HFIP, which was insoluble in CH2Cl2, was readily
recovered by evaporation of the water and reused for the next run.
All the products were known compounds and were characterized
by comparison with authentic samples.
d
¼
C
2,6-Dibromo-4,4-difluoro-1,3,5,7-tetramethyl-8-undecyl-4-
bora-3a,4a-diaza-s-indacene (2h): red solid; m.p. 202e205 ꢀC; 1H
NMR (500 MHz, CDCl3):
18H, CH2), 2.44 (s, 6H, CH3), 2.57 (s, 6H, CH3), 3.70e3.74 (m, 2H,
CH2). 13C NMR (125 MHz, CDCl3):
d
¼ 0.88e0.91 (t, 3H, CH3), 1.22e1.65 (m,
d
¼ 152.3, 147.3, 137.7, 130.5, 112.0,
31.8, 31.7, 30.3, 29.0, 22.6, 18.4, 15.5, 14.1, 13.7. EI-MS: m/z ¼ 560
[M]þ. Anal. Calcd for C24H35BBr2F2N2: C, 51.46; H, 6.30; N, 5.00.
Found: C, 51.47; H, 6.25; N, 5.02.
2,6-Dibromo-4,4-difluoro-1,3,5,7-tetramethyl-8-phenyl-4-
bora-3a,4a-diaza-s-indacene (2a): red solid; m.p. 228e232 ꢀC
2,6-Dibromo-4,4-difluoro-1,3,5,7-tetramethyl-8-ethoxycarb
(229e231 ꢀC) [18]; 1H NMR (500 MHz, CDCl3):
d
¼ 1.36 (s, 6H, CH3),
onyl-4-bora-3a,4a-diaza-s-indacene (2i): red solid; m.p. > 250 ꢀC;
2.61 (s, 6H, CH3), 7.52e7.53 (m, 5H, ArH). 13C NMR (125 MHz,
1H NMR(500 MHz, CDCl3):
d
¼ 1.42e1.45(t, 3H), 2.13(s, 6H), 2.56 (s,
4.43e4.48 (q, 2H); 13C NMR(125 MHz, CDCl3):
d
¼ 164.5,
CDCl3):
13.6.
d
¼ 153.9, 142.1, 140.6, 134.4, 130.4, 129.5, 129.4, 127.8, 111.8,
6H),
d
154.6, 135.9, 129.8, 126.9, 122.8, 63.2, 13.8, 12.7, 10.5. EI-MS: m/
z ¼ 478 [M]þ. Anal. Calcd for C16H17BBr2F2N2O2: C, 40.21; H, 3.59; N,
5.86. Found: C, 40.16; H, 3.62; N, 5.80.
2,6-Dibromo-4,4-difluoro-8-(4-methoxyphenyl)-1,3,5,7-tetra
methyl-4-bora-3a,4a-diaza-s-indacene (2b): red solid; m.p.
238e240 ꢀC (236e238 ꢀC) [18]; 1H NMR (500 MHz, CDCl3):
d
¼ 1.47
2,6-Dibromo-4,4-difluoro-8-(morpholinomethyl)-1,3,5,7-tet
ramethyl-4-bora-3a,4a-diaza-s-indacene (2j): red solid; m.p.
(s, 6H, CH3), 2.62 (s, 6H, CH3), 3.91 (s, 3H, OCH3), 7.06 (d, J ¼ 8.65 Hz,
2H, ArH), 7.16 (d, J ¼ 8.65 Hz, 2H, ArH). 13C NMR (125 MHz, CDCl3):
228e231 ꢀC; 1H NMR (500 MHz, CDCl3):
(s, 3H, CH3), 2.47 (s, 3H, CH3), 2.60 (s, 3H, CH3), 3.74 (t, 4H, CH2), 3.76
d
¼ 2.32 (s, 3H, CH3), 2.39
d
¼ 160.6, 153.7, 142.3, 140.6, 130.9, 130.8, 129.1, 128.8, 126.3, 114.8,
111.7, 55.4, 13.9, 13.7.
Scheme 1. 2,6-dihalogenation of BODIPYs in ChCl/HFIP.
Scheme 2. Preparation of ChCl/HFIP.