In these [2.2]paracyclophane derivatives, g-9 and m-10, electron-donating
dimethylamine group and the electron-accepting dimesytylboryl moiety are introduced at the pseudo-gem and pseudo-meta positions. In order to synthetize the
emitter g-9 (see Scheme 13.4), 4-bromo-13-amino[2.2]paracyclophane g-I was
methylated using dimethyl sulfate as methylation agent in acetone using potassium
carbonate as base. Then lithiation of the bromide g-J followed by addition of
dimesitylboron fluoride was achieved to give g-9 a 59% yield.
The synthesis of the m-10 isomer was initiated by the amination of the 4,15dibromo-[2.2]paracyclophane m-K via copper-assisted coupling reaction using
hydroxyproline as ligand and aqueous ammoniac. Then, the same reaction sequence
used for the synthesis of g-9 gave racemate m-10 with an overall yield of 16% over
the three synthetic steps (see Scheme 13.5).
In terms of photophysical properties, compound g-9 displays a broad and moderately intense absorption band centered at 374 nm, which was assigned using
theoretical calculations to the intramolecular charge transfer transition from the
HOMO, located on dimethylaminophenyl moiety, to the LUMO, localized on
dimesitylborylphenyl unit. For m-10, the assignation of this ICT band was found
to be more difficult because of the very small oscillator strength (0.0209) of the first
NH 2
Br
Me 2 SO 4 , K 2 CO 3
Acetone, RT
N
Br
1) n-BuLi, THF, -78°C
2) Mes 2 BF, THF, -78°C to RT
N
B(Mes) 2
g-J 91%
racemate g-9
59%
g-I
Scheme 13.4 Synthesis of g-9
Br
Br
1) NH 3 .H 2 O, CuI, 4-hydroxy-L-proline
K 2 CO 3, DMSO, 110 °C
1) n-BuLi, THF, -78°C
2) Mes 2 BF, THF, -78°C to RT
Br
N
B(Mes)2
N
Br
H 2 N
Me 2 SO 4 , K 2 CO 3
Acetone, RT
m-I 56%
m-J 72%
Racemate m-10
40%
m-K
Scheme 13.5 Synthesis of m-10
304
G. Pieters and L. Frederic
dimethylamine group and the electron-accepting dimesytylboryl moiety are introduced at the pseudo-gem and pseudo-meta positions. In order to synthetize the
emitter g-9 (see Scheme 13.4), 4-bromo-13-amino[2.2]paracyclophane g-I was
methylated using dimethyl sulfate as methylation agent in acetone using potassium
carbonate as base. Then lithiation of the bromide g-J followed by addition of
dimesitylboron fluoride was achieved to give g-9 a 59% yield.
The synthesis of the m-10 isomer was initiated by the amination of the 4,15dibromo-[2.2]paracyclophane m-K via copper-assisted coupling reaction using
hydroxyproline as ligand and aqueous ammoniac. Then, the same reaction sequence
used for the synthesis of g-9 gave racemate m-10 with an overall yield of 16% over
the three synthetic steps (see Scheme 13.5).
In terms of photophysical properties, compound g-9 displays a broad and moderately intense absorption band centered at 374 nm, which was assigned using
theoretical calculations to the intramolecular charge transfer transition from the
HOMO, located on dimethylaminophenyl moiety, to the LUMO, localized on
dimesitylborylphenyl unit. For m-10, the assignation of this ICT band was found
to be more difficult because of the very small oscillator strength (0.0209) of the first
NH 2
Br
Me 2 SO 4 , K 2 CO 3
Acetone, RT
N
Br
1) n-BuLi, THF, -78°C
2) Mes 2 BF, THF, -78°C to RT
N
B(Mes) 2
g-J 91%
racemate g-9
59%
g-I
Scheme 13.4 Synthesis of g-9
Br
Br
1) NH 3 .H 2 O, CuI, 4-hydroxy-L-proline
K 2 CO 3, DMSO, 110 °C
1) n-BuLi, THF, -78°C
2) Mes 2 BF, THF, -78°C to RT
Br
N
B(Mes)2
N
Br
H 2 N
Me 2 SO 4 , K 2 CO 3
Acetone, RT
m-I 56%
m-J 72%
Racemate m-10
40%
m-K
Scheme 13.5 Synthesis of m-10
304
G. Pieters and L. Frederic