Synthesis of 10-(4-heptyloxyphenyl)-2-[2-methyl-2-(4-methylphenylsulfonyl)- 1-oxopropyl)-9-oxothioxanthenium hexafluorophosphate(V)

Full text of DOI:10.1134/S1070428009010230

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 1, pp. 158–159. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © V.A. Loskutov, V.V. Shelkovnikov, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 1, pp. 160–161.
SHORT
COMMUNICATIONS
Synthesis of 10-(4-Heptyloxyphenyl)-2-[2-methyl-
2-(4-methylphenylsulfonyl)-1-oxopropyl)-9-oxothioxanthenium
Hexafluorophosphate(V)
V. A. Loskutov and V. V. Shelkovnikov
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
e-mail: val@nioch.nsc.ru
Received March 17, 2008
DOI: 10.1134/S1070428009010230
The efficiency of the initiation stage in photo-
chemical polymerization of unsaturated compounds
depends on the reactivity of initiator and radicals
formed as a result of its decomposition by the action of
light. We previously [1] synthesized new thioxanthen-
9-one-based initiators of photopolymerization which,
unlike known initiators, contained two photochem-
ically active cationic centers, sulfonium and ammoni-
um (or phosphonium). In the present communication
we report on the synthesis of thioxanthenium hexa-
fluorophosphate(V) containing a tosylisobutyryl resi-
due. According to the data of [2], derivatives of
α-sulfonyl ketones constitute a known class of highly
effective photoinitiators. The target compound I was
synthesized according to the scheme shown below.
uenesulfinate to afford tosylisobutyryl derivative V,
and condensation of the latter with heptyl phenyl ether
in a mixture of methanesulfonic acid with phosphoric
anhydride, followed by treatment with potassium
hexafluorophosphate(V), resulted in the formation of
10-(4-heptyloxyphenyl)-2-[2-methyl-2-(4-methyl-
phenylsulfonyl)-1-oxopropyl]thioxanthen-10-ium
hexafluorophosphate(V) (I). The structure of the newly
synthesized compounds was confirmed by spectral and
analytical data.
Hexafluorophosphate I was used to initiate photo-
chemical polymerization of acrylic monomers under
laser flash excitation (both single- and two-photon).
The results will be reported elsewhere.
2-(2-Methyl-1-oxopropyl)-9H-thioxanthen-9-one
(II) was synthesized according to the procedure re-
ported in [3], mp 140–144°C; published data [3]:
mp 144–145°C.
Bromination of 2-isobutyrylthioxanthen-9-one (II)
gave α-bromo ketone III which was oxidized to sulf-
oxide IV with cerium(IV) ammonium nitrate (CAN) in
acetonitrile. Compound IV reacted with sodium p-tol-
O
O
O
O
O
O
Me
Br
Me
Br
Me
Br2
CAN
Me
Me
Me
S
S
S
O
II
III
IV
(1) PhOC7H15
MeSO3H, P2O5
(2) KPF6
O
O
O
S
O
Me C6H4Me-4
Me C6H4Me-4
4-MeC6H4SO2Na
S
S
O
O
Me O
Me O
S
PF6
O
C6H4OC7H15-4
V
I
158

SYNTHESIS OF 10-(4-HEPTYLOXYPHENYL)-...
159
(0.44 mmol), and heptyl phenyl ether, 0.16 g
(0.83 mmol), were added to a 10:1 mixture of meth-
anesulfonic acid with phosphoric anhydride, 3 ml, and
the resulting mixture was stirred for 3.5 h at 20–25°C.
Ice was added to cool the mixture to 5°C, a solution of
0.26 g (1.4 mmol) of KPF6 in 3 ml of water was added,
and the mixture was stirred for 0.5 h and treated with
methylene chloride. The organic phase was separated,
washed with water, dried over anhydrous sulfate, and
evaporated to dryness. The residue was reprecipitated
from methylene chloride with diethyl ether and ad-
ditionally recrystallized from ethanol. Yield 0.16 g
(47%), mp 93–98°C. IR spectrum, ν, cm–1: 2929, 2857
(C–H); 1680 (C=O); 1587 (C=C), 843 (P–F). 1H NMR
spectrum, δ, ppm: 0.87 t (3H, CH3CH2, J = 6.8 Hz);
1.28 m and 1.74 m (10H, CH2); 1.62 s and 2.44 s (9H,
CH3); 3.99 t (2H, OCH2, J = 6.8 Hz); 7.05 d, 7.33 d,
7.62 d, and 7.71 d (8H, C6H4, J = 8.0 Hz); 7.93 m (3H,
5-H, 6-H, 7-H), 8.03 m (1H, 4-H), 8.37 m (1H, 8-H),
8.59 m (1H, 3-H), 9.05 m (1H, 1-H). 19F NMR spec-
trum: δF 89.85 ppm, d (JF, P = 713.6 Hz). Found, %:
C 57.53; H 5.04; F 15.14; S 8.35. C37H39O5S2·PF6.
Calculated, %: C 57.51; H 5.05; F 14.76; S 8.29.
2-(2-Bromo-2-methyl-1-oxopropyl)-9H-thioxan-
then-9-one (III). A mixture of 2.4 g (8.5 mmol) of
oxothioxanthene II, 0.9 ml (18 mmol) of bromine, and
15 ml of methylene chloride was kept for 20 h at 20–
25°C. The precipitate was filtered off, washed with di-
ethyl ether, and recrystallized from chloroform–etha-
nol. Yield 2.4 g (78%), mp 122–124°C. IR spectrum, ν,
1
cm–1: 1672, 1642 (C=O); 1592 (C=C). H NMR spec-
trum, δ, ppm: 2.08 s (6H, CH3), 7.59 m (3H, 5-H, 6-H,
7-H), 7.64 d (1H, 4-H, J = 8.7 Hz), 8.31 d.d (1H, 3-H,
J = 8.7, 1.9 Hz), 8.61 d (1H, 8-H, J = 8.0 Hz), 9.47 d
(1H, 1-H, J = 1.9 Hz). Found: m/z 359.98017 [M]+.
C17H13BrO2S. Calculated: M 359.98201.
2-(2-Bromo-2-methyl-1-oxopropyl)-9H-thioxan-
then-9-one 10-oxide (IV). A solution of 0.18 g
(0.5 mmol) of compound III in 10 ml of acetonitrile
was heated to 35–40°C, a solution of 1.1 g (2 mmol) of
cerium(IV) ammonium nitrate in 3 ml of water was
added, and the mixture was stirred for 0.5 h at that
temperature (until it became homogeneous) and then
for 2.5 h at 20–25°C. The mixture was poured into ice
water, and the precipitate was filtered off. Yield 0.16 g
(85%), mp 142.5–145°C (from ethanol). IR spectrum,
ν, cm–1: 1687, 1666 (C=O); 1589 (C=C); 1037 (S=O).
1H NMR spectrum, δ, ppm: 2.03 s and 2.04 s (3H each,
CH3), 7.73 t.d and 7.87 t.d (1H each, 6-H, 7-H, J = 8.0,
2.0 Hz), 8.16 d.d (1H, 5-H, J = 8.0, 2.0 Hz), 8.24 d
(1H, 4-H, J = 8.0 Hz), 8.36 d.d (1H, 8-H, J = 8.0,
2.0 Hz), 8.50 d.d (1H, 3-H, J = 8.0, 1.6 Hz), 9.03 d
(1H, 1-H, J = 1.6 Hz). Found: m/z 375.97518 [M]+.
C17H13BrO3S. Calculated: M 375.97692.
The IR spectra were recorded in KBr on a Vector 22
1
instrument. The H and 19F NMR spectra were ob-
tained on a Bruker AC-200 spectrometer from solu-
tions in CDCl3; the chemical shifts were measured
relative to the residual solvent signal (1H) or C6F6 (19F,
internal reference). The molecular weights and ele-
mental compositions were determined from the high-
resolution mass spectra which were recorded on
a Finnigan MAT-8200 mass spectrometer. The progress
of reactions and the purity of products were monitored
by TLC on Silufol UV-254 plates using benzene or
chloroform as eluent.
2-[2-Methyl-2-(4-methylphenylsulfonyl)-1-oxo-
propyl)-9H-thioxanthen-9-one 10-oxide (V). A mix-
ture of 0.38 g (1 mmol) of thioxanthene oxide IV,
0.36 g (2 mmol) of sodium p-toluenesulfinate, and
6 ml of DMSO was stirred for 0.5 h at 20–25°C and
was then left to stand for 40 h. The mixture was diluted
with ice water, and the precipitate was filtered off.
Yield 0.42 g (93%), mp 139–143°C. IR spectrum, ν,
cm–1: 1668 (C=O); 1587 (C=C); 1291, 1130 (SO2);
1041 (S=O). 1H NMR spectrum, δ, ppm: 1.68 s, 1.69 s,
and 2.43 s (3H each, CH3); 7.32 d and 7.66 d (4H,
C6H4, J = 8.0 Hz), 7.73 t.d and 7.86 t.d (1H each, 6-H,
7-H, J = 8.0, 1.2 Hz), 8.17 d.d (1H, 5-H, J = 8.0,
1.2 Hz), 8.25 d (1H, 4-H, J = 8.2 Hz), 8.36 d.d (1H,
8-H, J = 8.0, 1.2 Hz), 8.44 d.d (1H, 3-H, J = 8.2, 1.8 Hz),
8.72 d (1H, 1-H, J = 1.8 Hz). Found: m/z 452.07474
[M]+. C24H20O5S2. Calculated: M 452.07521.
This study was performed under financial support
by the Presidium of the Russian Academy of Sciences
(project no. 8-3) and by the Siberian Division of the
Russian Academy of Sciences (integration project nos.
15, 17, 33).
REFERENCES
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Polym. J., 1997, vol. 33, p. 881; Giaroni, P., Di Bat-
tista, P., and Li Bassi, G., WO Patent no. 010270, 1997;
Chem. Abstr., 1997, vol. 126, no. 294708u.
10-(4-Heptyloxyphenyl)-2-[2-methyl-2-(4-meth-
ylphenylsulfonyl)-1-oxopropyl]thioxanthen-10-ium
hexafluorophosphate(V) (I). Compound V, 0.2 g
3. Ashton, M.J., Chapman, R.F., and Loveless, A.H.,
J. Med. Chem., 1980, vol. 23, p. 653.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 1 2009