Electron beam-induced fries rearrangement of sulfonamide and sulfonate crystals

Article abstract of DOI:10.1246/cl.2005.266

The electron beam (EB) sensitivity of sulfonic acid derivatives in the crystalline state was much higher than that of the corresponding carboxylic acid derivatives, which was distinct from the results using other energy sources such as heat and UV; especially, sulfonamide derivatives could undergo the chemoselective Fries rearrangement to give ortho and para products in the ratio of ca. 7/3 without the meta isomer. Copyright

Full text of DOI:10.1246/cl.2005.266

2
66
Chemistry Letters Vol.34, No.2 (2005)
Electron Beam-Induced Fries Rearrangement of Sulfonamide and Sulfonate Crystals
ꢀy;yy
ꢀyy yy
Yasunari Maekawa, and Masaru Yoshida
Jun Kato,
Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510
Department of Material Development, Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki 370-1292
y
yy
(Received November 22, 2004; CL-041399)
The electron beam (EB) sensitivity of sulfonic acid deriva-
diation dose of 10 MGy (irradiation for 57.5 min), the conver-
sions of 2 and 4 were only 2 and 7%. Whereas, those of 1a
and 3 reached to 50 and 44%, and then went up to 75 and
84% with the dose of 20 MGy. It was noted that the sensitivity
of sulfonic acid derivatives to EB was much higher than that
of the corresponding carboxylic acid derivatives. This was dis-
tinct from the results using other energy sources such as heat
tives in the crystalline state was much higher than that of the cor-
responding carboxylic acid derivatives, which was distinct from
the results using other energy sources such as heat and UV; es-
pecially, sulfonamide derivatives could undergo the chemose-
lective Fries rearrangement to give ortho and para products in
the ratio of ca. 7/3 without the meta isomer.
7
–9
and UV.
The EB irradiation of sulfonamide 1a with the dose of
10 MGy gave three main products, which were observed in
GC and HPLC. These products were isolated from each other
by a reversed phase preparative HPLC. Then, the isolated prod-
ucts were assigned to o- and p-aminophenyl phenyl sulfones (5a
Ionizing radiation such as ion and electron beams possesses
high energy and narrow beam size enough to modify the struc-
tures and properties of organic molecules and polymeric materi-
1
als on atomic and molecular levels. Because of rapid nanoscale
1
13
scanning, the electron beam (EB) irradiation has attracted much
attention in recent years as a promising technique for nanolithog-
raphy and fabrication of future nanodevices in a variety of fields
and 6a), and aniline (7) by IR, H and C NMR, and MS
(Scheme 1). Namely, the EB irradiation of 1a in the crystalline
state induced Fries rearrangement to give two regio isomers (5a
and 6a) in 24 and 10% yields with a radiolytic product 7 in an
8.0% yield (Table 1). The ortho/para ratio was approximately
7:3 throughout the reaction. Likewise, the EB irradiation with
10 MGy of sulfonate 3 in the crystalline state induced Fries rear-
rangement to give o-hydroxyphenyl p-tolyl sulfone 8 and the
para isomer 9 in yields of 6.0 and 2.3% along with the scission
product, phenol (10) in a yield of 5.6% (Scheme 1). In the EB
induced reactions of both sulfonamide and sulfonate derivatives,
other degradation products could not be detected in GC and
HPLC. It is noteworthy that the reactions of sulfonamide and
sulfonate derivatives shown in Scheme 1 are the first example
of radiation-induced Fries rearrangement via direct excitation
and/or ionization.
2
such as electronics, photonics, biologics, and mechanics. Nev-
ertheless, there have been few reports on the useful EB induced
3
reactions of organic compounds, which are required to design
materials for these applications, although a number of studies
on radiation-induced reactions of simple organic compounds,
4
such as alkanes, alcohols, and stilbenes, have been conducted.
Recently, we investigated the EB induced reactions of either
5
6
cinnamic acid derivatives or sulfonium salts in the crystalline
state, together with comparison with the corresponding photore-
actions. These reactions proceeded via direct ionization and ex-
citation of target molecules without any influence of a reaction
medium. In addition, the crystalline lattice restrictions simplified
the EB induced reactions, which generally lead to many products
in complex mechanism. The Fries rearrangement of both carbox-
ylic and sulfonic acid derivatives is known to proceed using var-
Although both sulfonic acid derivatives showed much
higher EB sensitivity, compared with the corresponding carbox-
ylic acid derivatives, sulfonamide 1a could further afford the
7
8
ious energy sources such as heat or microwave with catalyst,
9
and UV light. It is notable that these reactions are accompanied
by the transformation of ester and amide linkages to hydrophilic
phenol and aniline moieties, respectively; especially, an acidic
sulfonamide can be converted to the corresponding basic aniline
derivatives. Thus, we report herein the novel EB induced Fries
rearrangement of amide and ester derivatives in the crystalline
100
O
S
3 (X=O)
Ar
X
80
O
1
a (X=NH)
1
0
state, which has the potential of utilization in nanolithography.
60
40
20
0
The EB induced reactions of the amide and ester derivatives
in the crystalline state were carried out as follows. Finely pow-
dered crystals recrystallized from alcohol were placed in a hol-
low (10 mm in diameter, 1 mm in depth) of a glass plate, and
were covered with a Kapton film. The samples, which were
placed on a water-cooled copper plate, were irradiated with
Ar
C
O
X
4 (X=O)
2 (X=NH)
ꢂ1
EB (1 MeV, 1 mA) at a dose rate of 2.9 kGyꢁs , using a cascade
0
5
10
15
20
25
type electron accelerator (Dynamitron). The crystals of benzene-
sulfonanilide (1a), benzanilide (2), phenyl p-toluenesulfonate
Absorbed Dose / MGy
(
2
3), and phenyl benzoate (4) were irradiated with doses of 1–
0 MGy (0.54–10.8 mCꢁcmꢂ2); then, these conversions were de-
termined by GC and HPLC. As shown in Figure 1, with the irra-
Figure 1. The conversion of the starting compounds (sulfonamide 1a,
sulfonate 3, and their corresponding carboxylic acid derivatives,
2 and 4) as a function of EB dose absorbed by the crystals.
Copyright Ó 2005 The Chemical Society of Japan

Chemistry Letters Vol.34, No.2 (2005)
267
HX
rearrangement to produce only para isomer 6d. The formation
of 6d ruled out the concerted mechanism for the Fries rearrange-
ment, which gives only an ortho isomer. Accordingly, the EB in-
duced Fries rearrangement of sulfonamides is inferred to pro-
ceed through radical intermediates obtained by the homolytic
cleavage of the S–N bond via the lowest excited state. It is well
known that radiolysis of organic molecules leads primarily to
upper excited states by direct excitation or recombination of dis-
sociated radical cation and a free electron regardless of the mo-
lecular structure. Accordingly, the upper excited state of sulfona-
mides produced by EB irradiation is inferred to lead to the lowest
excited state, which is the same state as photoreaction, resulting
in the homolytic cleavage of the S–N bond to give rise to Fries
rearrangement products through radical intermediates. In con-
trast to sulfonic acid derivatives, the corresponding carboxylic
acid derivatives undergo Fries rearrangement by photolysis but
not by radiolysis under the same conditions. This difference
should result from the fact that the carboxylic acid derivatives
in upper excited states can not lead to the lowest excited state,
from which the photo-Fries rearrangement proceeds; as the re-
sult, it should be relaxed to the ground state via the other thermal
processes.
In conclusion, the EB irradiation of sulfonic acid derivatives
in the crystalline state underwent the Fries rearrangement to
yield the aniline and phenol derivatives, respectively; whereas,
the corresponding carboxylic acid derivatives did not give rise
to any rearrangement products, though both sulfonic and carbox-
ylic acid derivatives undergo photo-Fries rearrangement. Only
sulfonamide derivatives could provide the Fries rearrangement
products preferentially to give ortho and para products in the ra-
tio of ca. 7/3 without the meta isomer. It should be noted that this
rearrangement was the first radiation-induced transformation
from acid (sulfonamides) to base (anilines); thus, this EB-Fries
rearrangement seems to be very useful for nanolithography
and nanofabrication. Further studies on the detailed mechanism
of the above rearrangement as well as other EB induced reac-
tions in restricted matrix are underway.
O
S
EB
O
O
S
Ar
X
Ar
S
+
Ar
XH
+
XH
O
h
ν
O
O
1
3
(X=NH)
(X=O)
5
8
6
9
7
10
Ortho
Para
HX
EB
Ar
C
O
X
Ar
C
O
+
Ar
C
XH
+
XH
h
ν
O
2
4
(X=NH)
(X=O)
Scheme 1. Fries rearrangement of amide and ester derivatives
from sulfonic and carboxylic acids upon EB and UV in the crystalline
state.
Table 1. Electron beam-induced Fries rearrangement of arylsul-
a
fonamides (1a–1d) in the crystalline state
c
b
Fries rearr. products /%
Reaction substrate
Conv. /%
ortho
para
O
S
O
O
S
NH
NH
1a
1b
1c
50
55
41
24
10
CH3
16
10
13
O
O
S
N
(3.3 : 1)
N.D.d
O
CH3
CH3
O
S
NH
1d
21
O
CH3
a
b
Prepared according to the procedure described in Ref. 11. Conversion
c
after irradiation (10 MGy). Determined by GC. All yields were calculat-
d
ed on the consumed sulfonamide derivatives. Not detected.
Fries rearrangement products with higher selectivity than sulfo-
nate 3. Thus, the EB induced Fries rearrangements of the other
arylsulfonamides 1b–1d were examined with the dose of 10
MGy for comparison with 1a; these results are summarized in
Table 1. p-Toluenesulfonanilide (1b), which possesses one addi-
tional methyl group on the phenyl group attaching to sulfone in
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(
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1
a–1c; however, as expected, it underwent regioselective Fries
Published on the web (Advance View) January 26, 2005; DOI 10.1246/cl.2005.266