1-Hydroxy-2(1H)-quinolone-Based Photoacid Generators
FULL PAPER
quinolin-2(1H)-one) were separated by column chromatography with
ethyl acetate/hexane as eluent.
The quantum yields for photogeneration of sulfonic acids were analyzed
by 1H NMR spectroscopy by employing valerophenone as an actinome-
ter. The percentage of acid generated was determined by calculating the
gradual increase in the peak area of the sulfonic acids with anisole as an
Quinolin-2(1H)-one (6): White solid; Rf (30% ethyl acetate/hexane)
1
0.50 cmÀ1; H NMR (CDCl3, 200 MHz): d=6.70 (d, 1H, J=9.4 Hz), 7.25–
1
internal standard by H NMR.
7.36 (m, 2H), 7.48–7.59 (m, 2H), 7.81 (m, 1H, J=9.6 Hz) 11.39 (brs,
1H), 13C NMR (CDCl3, 100 MHz): d=116.0, 119.2, 121.6, 123.0, 129.3,
130.9, 138.7, 141.2, 164.4.
Synthesis of monomer 1-(p-styrenesulfonyloxy)-2-quinolone (SSQL, 11):
Et3N (3.68 mL, 26.48 mmol) was added to a mixture of 1-hydroxy-2(1H)-
quinolone (2 g, 13.24 mmol) and p-styrenesulfonyl chloride (4 g,
19.73 mmol) in dry CH2Cl2 over 5 min at 08C, and then the reaction mix-
ture was continuously stirred at room temperature overnight. After com-
pletion of the reaction it was quenched with ice-cold water and diluted
with CH2Cl2. The organic layer was separated, dried over Na2SO4, and
the solvent removed under vacuum. The dark yellow crude solid was pu-
rified by column chromatography (40% ethyl acetate/hexane) to give 11
(85%) as a light yellow solid; Rf (40% ethyl acetate/hexane) 0.50; m.p.
~
The quantum yield for the photogeneration of carboxylic acids was ana-
lyzed by employing valerophenone as an actinometer. The progress of
the photolysis was monitored by taking 5 mL of aliquot at regular time in-
tervals and analyzing by HPLC with hexane/propan-2-ol (9:1) as eluent
at a flow rate of 1 mLminÀ1 (detection: UV 254 nm). The percentage of
carboxylic acid generated was determined by calculating the gradual in-
crease in the peak area of the carboxylic acid.
General procedure for the synthesis of sulfonates of 1-hydroxy-2(1H)-
quinolone (8a–e): Et3N (0.43 mL, 3.09 mmol) was added dropwise to a
mixture of sulfonyl chloride (2.33 mmol) and 1-hydroxy-2(1H)-quinolone
(250 mg, 1.55 mmol) in dry CH2Cl2 at 08C. The reaction mixture was
then stirred overnight at room temperature. After completion of the re-
action (as indicated by TLC), it was quenched with ice-cold water and di-
luted with CH2Cl2. The organic layer was separated, dried over Na2SO4,
and the solvent removed under vacuum to yield crude sulfonate.
105–1078C; FTIR (KBr): nmax =1650, 1363 cmÀ1
;
1H NMR (CDCl3,
200 MHz): d=5.50 (d, 1H, J=10.8 Hz), 5.94 (d, 1H, J=17.4 Hz), 6.64 (d,
1H, J=9.6 Hz), 6.79 (dd, 1H, J1 =10.8 Hz, J2 =17.6 Hz), 7.29–7.32 (m,
1H), 7.56–7.76 (m, 6H), 8.11 (d, 2H, J=8.4 Hz); 13C NMR (CDCl3,
50 MHz): d=112.9, 118.8, 119.8, 121.7, 123.6, 124.3, 126.7 (2C), 128.2,
130.0 (2C), 131.4, 133.7, 135.2, 139.7, 144.4, 157.0.
General procedure for synthesis of copolymers 14 and 15: SSQL mono-
mer (1.526 mmol) and LA or MMA (1.526 mmol) were mixed in a 10 mL
glass tube and dissolved by adding dry THF. AIBN (0.009 mmol) was
added and the tube was then purged with nitrogen for 30 min. The reac-
tion mixture was heated at 808C for 3 h. After completion of the reaction
the tube was immersed in liquid nitrogen and the reaction mixture dilut-
ed with THF. Polymer was then precipitated from hexane and the process
was repeated three times to remove unconverted monomer and AIBN. It
was then dried under high vacuum for 6 h.
1-(Methanesulfonyloxy)-2-quinolone (8a): The dark yellow crude solid
sulfonate was purified by column chromatography (30% ethyl acetate/
hexane) to give 8a (90%) as a yellow solid; Rf (30% ethyl acetate/
~
hexane) 0.55; m.p. 108–1108C; FTIR (KBr): nmax =1683, 1350 cmÀ1
;
1H NMR (CDCl3, 200 MHz): d=3.78 (brs, 3H), 6.79 (d, 1H, J=9.6 Hz),
7.33–7.41 (m, 1H), 7.64 (s, 1H), 7.68–7.69 (m, 1H), 7.24 (brs, 1H), 7.73–
7.82 (m, 2H); 13C NMR (CDCl3, 50 MHz): d=41.9, 121.6, 119.7, 127.4,
123.8, 128.3, 131.7, 139.4, 140.0, 157.4; HRMS (ES+) calcd for
C10H9NO4S [M+H+]: 239.0252, found: 239.0248.
Polymer SSQL-LA (14): Off-white liquid; UV/Vis (MeOH): lmax
=
330 nm, FTIR (neat): nmax =1650, 1355 cmÀ1
;
1H NMR (CDCl3,
~
1-(Benzenesulfonyloxy)-2-quinolone (8c): The crude product was puri-
fied by column chromatography (30% ethyl acetate/hexane) to give 8c
(93%) as an off-white solid; m.p: 118–1228C; Rf (30% ethyl acetate/
hexane) 0.40; FTIR (KBr) nmax =1685, 1378 cmÀ1 1H NMR (CDCl3,
;
~
200 MHz): d=0.68–0.96 (m), 1.02–2.18 (m), 2.12–2.54 (m), 3.55–4.46 (m),
6.66–7.50 (m), 7.55–8.12 (m).
200 MHz): d=6.64 (d, 2H, J=9.4 Hz), 7.30–7.34 (m, 1H), 7.58–7.67 (m,
5H), 7.72–7.81 (m, 2H), 8.17 (d, 2H, J=7.2 Hz); 13C NMR (CDCl3,
50 MHz): d=122.9, 119.8, 121.7, 123.7, 123.9, 128.2, 129.1 (2C), 129.8
(2C), 131.5, 135.2, 135.3, 139.7, 157.0; HRMS (ES+) calcd for
C15H11NO4S [M+H+]: 301.0408, found: 301.0411.
1-(p-Methylbenzenesulfonyloxy)-2-quinolone (8d):[48] Purification of the
crude mixture by column chromatography (20% ethyl acetate/hexane)
gave 8d as an off-white solid; m.p. 121–1248C; Rf (30% ethyl acetate/
~
;
hexane) 0.45; FTIR (KBr): nmax =1378, 1678 cmÀ1 1H NMR (CDCl3,
Acknowledgements
We thank DST (SERC Fast Track Scheme) for financial support, DST-
FIST for 400 MHz NMR and Prof. S. Nanda for HPLC. M.I. and A.J. are
thankful to CSIR (India) and R.B. and S.A. to UGC (India) for their re-
search fellowship.
400 MHz): d=2.49 (s, 3H), 6.64 (d, 1H, J=9.6 Hz), 7.29–7.33 (m, 1H),
7.39–7.43 (m, 2H), 7.56–7.60 (m, 2H), 7.66–7.76 (m, 3H), 8.04 (d, 2H,
J=9.4 Hz), 8.35–8.40 (m, 2H); 13C NMR (CDCl3, 100 MHz): d=21.8,
112.9, 119.7, 121.6, 123.5, 128.1, 129.6, 129.7 (2C), 131.2, 131.5, 132.1,
134.0, 139.3, 146.2, 164.9; HRMS (ES+) calcd for C16H13NO4S [M+H+]:
315.0565, found: 315.0568.
[1] R. Ayothi, Y. Yi, H. B. Cao, W. Yueh, S. Putna, C. K. Ober, Chem.
[3] a) S. A. Kruger, C. Higgins, B. Cardineau, T. R. Younkin, R. L. Brai-
[5] J. H. Sim, S. Lee, H. J. Lee, R. Kasica, H. M. Kim, C. L. Soles, K. B.
[7] a) C. Li, F. Cheng, J. Lv, Y. Zhao, M. Liu, L. Jiang, Y. Yu, Soft
[8] a) D. Cao, M. Hu, C. Han, J. Yu, L. Cui, Y. Liu, Y. Cai, H. Wang, Y.
Henderson, W. Yueh, J. M. Roberts, K. E. Gonsalves, J. Mater.
1-(o-Nitrobenzenesulfonyloxy)-2-quinolone (8e): Compound 8e (80%)
was obtained as a yellow solid by purification of the crude product by
column chromatography (50% ethyl acetate/hexane); Rf (30% ethyl ace-
~
tate/hexane) 0.35; m.p: 133–1358C; FTIR (KBr): nmax =1668, 1363 cmÀ1
;
1H NMR (CDCl3, 200 MHz): d=6.54 (d, 1H, J=9.6 Hz), 7.02–7.29 (m,
2H), 7.48–7.57 (m, 1H), 7.67 (d, 1H, J=7.2 Hz), 7.85–7.96 (m, 2H),
8.07–8.21 (m, 3H); 13C NMR (CDCl3, 50 MHz): d=122.02, 122.3, 122.9,
123.6, 125.9, 126.9, 128.2, 132.0, 133.0, 133.6, 134.7, 137.8, 140.1, 148.6,
162.0; HRMS (ES+) calcd for C15H10N2O6S [M+H+]: 346.0259, found:
346.0251.
Photolysis and quantum yield measurements of the sulfonate esters:
0.05 mmol of sulfonate ester ACHTUNTRGEN(UGN 8a–e) was dissolved in MeOH/H2O (50:1)
and irradiated by a 125 W medium-pressure Hg lamp with Pyrex filter.
The progress of the reaction was monitored by 1H NMR analysis. After
completion of the reaction the solvent was removed under vacuum and
the photo products (sulfonic acid and quinolin-2(1H)-one) were separat-
ed by column chromatography with ethyl acetate/hexane as an eluant.
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
7
&
ÞÞ
These are not the final page numbers!