Cyclooxygenase inhibitors derived from thalidomide

Article abstract of DOI:10.1248/cpb.51.1098

Several N-3,5-dimethylphenylphthalimide analogs possessing more potent cyclooxygenase-inhibiting activity than that of aspirin were prepared during structural development studies based on thalidomide. Substituent effects on the activity were investigated.

Full text of DOI:10.1248/cpb.51.1098

1098
Notes
Chem. Pharm. Bull. 51(9) 1098—1102 (2003)
Vol. 51, No. 9
Cyclooxygenase Inhibitors Derived from Thalidomide
Mamiko SUIZU,a Yohei MUROYA,b Hiroki KAKUTA,a Hiroyuki KAGECHIKA,b Aya TANATANI,a
a
,a
*
Kazuo NAGASAWA, and Yuichi HASHIMOTO
a Institute of Molecular & Cellular Biosciences, The University of Tokyo; 1–1–1 Yayoi, Bunkyo-ku, Tokyo 113–0032,
Japan: and b Graduate School of Pharmaceutical Sciences, The University of Tokyo; 7–3–1 Hongo, Bunkyo-ku, Tokyo
113–0033, Japan. Received April 25, 2003; accepted July 1, 2003
Several N-3,5-dimethylphenylphthalimide analogs possessing more potent cyclooxygenase-inhibiting activity
than that of aspirin were prepared during structural development studies based on thalidomide. Substituent ef-
fects on the activity were investigated.
Key words thalidomide; cyclooxygenase; inhibitor; structure–activity relationship
pression of COX-2.28,29) In addition, we have recently demon-
Thalidomide (1) is a sedative/hypnotic drug, which was
strated that thalidomide directly inhibits COX-1/2, being
comparable in potency to aspirin.30) In this paper, we de-
scribe novel COX inhibitors derived from thalidomide, fo-
cusing on COX-1 and -2.
withdrawn from the market because of its severe teratogenic-
ity.1—3) In spite of this, research into thalidomide was not
halted, and the drug has been established to be effective
for the treatment of various diseases, including leprosy,
myeloma, and AIDS.2—4) We have demonstrated that thalido-
mide is a multi-target drug.2,3,5—17) We have been engaged in
structural development studies of thalidomide, and have ob-
tained tumor necrosis factor (TNF)-a production regulators
(including bi-directional ones, as well as pure inhibitors and
enhancers),2,3,5—7) androgen antagonists,2,3,8,9) peptidase in-
hibitors,3,10—13) glucosidase inhibitors,15,16) and thymidine
phosphorylase inhibitors.16) We suspected that cyclooxyge-
nase (COX) is another target molecule of thalidomide, be-
cause thalidomide is effective against colon and prostate can-
cers and possesses anti-angiogenic activity,17,18) in which
COX plays an important role.
COX is an enzyme which catalyzes the synthesis of
prostaglandins from arachidonic acid, and is well-known as a
target molecule of non-steroidal anti-inflammatory drugs
(NSAIDs), including aspirin.19—21) There are three isoforms
of COX, of which COX-1 and -2 have been well investigated.
COX-1 is constitutively expressed in most tissues, whereas
COX-2 is inducible. Overexpression of COX-2 has been de-
tected in various tumors and its role in carcinogenesis and
angiogenesis has been well-documented.21—23) Consequently,
COX-2 has been suggested to be an important pharmacologi-
cal target for the prevention and treatment of cancer.21—23)
Attempts have been made to apply COX-2 inhibitors, includ-
ing celexocib and sulindac, for chemoprevention of various
cancers, including colon and prostate cancers.24,25) Recently,
another subtype, COX-3, was shown to be a COX-1 variant,
which is selectively inhibited by acetaminophen and other
analgestic/antipyretic drugs.26,27) Thus, inhibition of COX-3
is considered to represent the primary mechanism through
which these drugs decrease pain and possibly fever.
Results and Discussion
Substituted phthalimide (2—28) analogs, including deoxy-
genated derivatives, with N-3,5-dimethylphenyl substituents
were selected based on our previous studies on COX-in-
hibitors derived from thalidomide, which suggested that the
3,5-dimethylphenyl substituent is superior for potent COX-
inhibiting activity.30)
Compounds (2—28) were prepared by usual synthetic
methods and the structures were confirmed by NMR
and mass spectrometry, and by appropriate analytical
values. Synthesis and chemical/physical data of several
of the compounds listed in Table 1 have already been
reported.5—8,10—17,30,31) Inhibitory activity of the compounds
toward COX-1 and COX-2 was assayed by the use of a Col-
orimetric COX (ovine) Inhibitor Screening Assay Kit (Cay-
man, No. 760111) according to the protocol recommended
by the supplier.
Although the IC50 values differed from experiment to ex-
periment, the results were basically reproducible, and typical
sets of data are presented in Fig. 2, and Table 1. In the assay
system, the IC50 values of aspirin for COX-1 and COX-2
were determined to be 90—100 mM and 100—110 mM, sug-
gesting that aspirin is a non-selective or slightly COX-1-se-
lective inhibitor. The activities of compounds are presented
as relative activities [RA values (RA1 and RA2, for COX-1
and COX-2 inhibitory activities, respectively)] defined as
IC50 (aspirin)/IC50 (test compound), and the selectivity index (SI val-
ues) was defined as IC50 (COX-1)/IC50 (COX-2). For compounds
with weak activity, IC30 (for RA values of less than 0.3) or
IC10 (for RA values of less than 0.1) values were used instead
of IC50 values. The assay was performed in duplicate, and re-
peated at least three times.
Thalidomide suppresses lipopolysaccharide-induced ex-
As shown in Table 1, phenylphthalimide analogs substi-
tuted at the 4-position (2—6) are inactive. However, substitu-
tion with the same series of functional groups at the 5-posi-
tion (7—10) resulted in COX-inhibitory activity with compa-
rable potency to that of thalidomide (Fig. 1), though the po-
tency is lower than that of aspirin. Broadly speaking, removal
of one carbonyl group of the phthalimide moiety, i.e., isoin-
Fig. 1. Structure of Thalidomide and Its COX-Inhibiting Activity
RA1, RA2: Relative inhibitory activity (versus aspirin) for COX-1 and COX-2, re-
spectively. SI: Selectivity index for COX-1 over COX-2. See text for details.
To whom correspondence should be addressed. e-mail: hashimot@iam.u-tokyo.ac.jp
© 2003 Pharmaceutical Society of Japan

September 2003
1099
Table 1. COX-Inhibitory Activity of Compounds (2—28) Derived from 3,5-Dimethylphenylphthalimide
Compound
A
B
C
D
X
Y
RA1
RA2
SI
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
NO2
NH2
NHMe
NMe2
NHAc
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
NO2
NH2
NMe2
NHAc
H
H
H
H
H
H
H
NO2
NH2
NMe2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
H2
H2
H2
H2
H2
O
O
O
O
O
O
O
O
O
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
Ͻ0.05
Ͻ0.05
Ͻ0.05
Ͻ0.05
Ͻ0.05
0.3
Ͻ0.05
0.4
0.2
Ͻ0.05
Ͻ0.05
1.9
1.1
2.6
25.0
12.1
1.0
1.2
0.6
Ͻ0.05
0.9
0.5
Ͻ0.05
Ͻ0.05
Ͻ0.05
Ͻ0.05
Ͻ0.05
0.9
0.3
Ͻ0.05
1.2
Ͻ0.05
Ͻ0.05
1.5
0.6
0.8
2.8
5.0
6.5
Ͻ0.05
0.5
Ͻ0.05
Ͻ0.05
0.5
—
—
—
—
—
2.7
(Ͼ5)
(Ͻ0.01)
5.4
—
—
0.7
0.6
0.3
0.1
0.4
5.9
(Ͻ0.04)
0.7
—
H
NO2
NH2
NHMe
NMe2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
NH2
NMe2
H
H
H
H
H
H
H
H
H
H
H
H
NO2
NH2
NMe2
NO2
H
H
H
H
H
H
H
NO2
NH2
NMe2
NHAc
(Ͻ0.05)
0.9
1.2
2.4
0.4
0.7
0.9
33.6
38.0
22.6
18.4
71.4
10.4
5.3
0.2
0.3
5.5
RA1, RA2: relative inhibitory activity (versus aspirin) for COX-1 and COX-2, respectively. SI: selectivity index for COX-1 over COX-2. See text, for details.
dolone derivatives (11—23), generally enhanced the COX- or dimethylamino (9, 15, 17, 20, 23, 27) group] show COX-1
inhibitory activity. Among the isoindolone derivatives, the 6- selectivity, with the sole exception of 8, which is COX-2 se-
amino derivative (16) and the 5-nitro derivative (18) are the lective. On the other hand, compounds with an electron-with-
most potent COX-1 inhibitor (25.0 times more potent than drawing nitro group (7, 18, 24, 25) show COX-2 selectivity,
aspirin) and COX-2 inhibitor (6.5 times more potent than as- though the selectivities of 24 and 25 are low. The effect of an
pirin), respectively. Further deoxygenation, i.e., isoindolyl acetylamino group on the COX-1/2 selectivity could not be
analogs (24—28), afforded much more potent COX-in- interpreted. The dose–response curves for COX-1 and -2 in-
hibitors than aspirin. Among this series of the compounds, hibition of 16 and 25 are presented in Fig. 2.
the 5-amino (26) and 5-nitro (25) analogs are the most potent
COX-1 (38.0 times more active than aspirin) and COX-2 substituents introduced into the phthalimide moiety of
(71.4 times more active than aspirin) inhibitors, respectively. methylthalidomide dramatically changes the COX-1/2 selec-
Though the structure-activity relationships remain to be tivity of the compounds, depending on the position of the
fully established, some aspects can be discussed, as follows.
substituent introduced.30) That finding, and the results pre-
Previously, we reported that the electronic nature of the
(1) Roughly speaking, compounds with a substituent of sented in this paper, should be useful for the development of
group “B” (7—10, 18—20, 25—28) or “C” (16—17) in superior COX-inhibitors.
Table 1 are more potent COX-inhibitors than the correspond-
ing isomers with a substituent of group “A” (2—6, 21—24)
Experimental
General Melting points were determined by using a Yanagimoto hot-
or “D” (12—14) in Table 1. This suggests that substitution at
the b-positions (positions 5 and 6) is better than that at the
a-positions (positions 4 and 7) for potent COX-inhibiting ac-
tivity, regardless of the electronic nature of the substituent.
Exceptions are the pairs of compounds 13/19 and 15/20. In
these pairs, 7-substituted compounds (13, 15) possess more
potent COX-inhibiting activity than the corresponding 5-sub-
stituted compounds (19, 20, respectively).
stage melting point apparatus and are uncorrected. Elemental analyses were
carried out in the Microanalytical Laboratory, Faculty of Pharmaceutical
Sciences, University of Tokyo, and were within Ϯ0.3% of the theoretical
values. NMR spectra were recorded on a JEOL JNM-GX400 (400 MHz)
spectrometer. Chemical shifts are expressed in ppm relative to tetramethylsi-
lane. Mass spectra were recorded on a JEOL JMS-DX303 spectrometer.
4-Substituted Phthalimides (General method) A mixture of 4-ni-
trophthalic anhydride (4.65 g, 24.1 mmol) and 3,5-xylidine (2.91 g,
24.0 mmol) in acetic acid (100 ml) was refluxed for 24 h. After cooling, the
mixture was poured into ice water. The precipitates were collected, and re-
crystallized from CH2Cl2/EtOH to give 2 (4.09 g, 58%).
(2) Among the compounds with potent/moderate COX-in-
hibiting activity, compounds with an electron-donating func-
tional group [amino (13, 16, 19, 22, 26), methylamino (14),
2: Yellow needles; mp 209—212 °C; 1H-NMR (CDCl3) 8.21 (1H, d,
Jϭ7.5 Hz), 8.15 (1H, d, Jϭ8.0 Hz), 7.97 (1H, t, Jϭ7.7 Hz), 7.07 (1H, s),

1100
Vol. 51, No. 9
Fig. 2. The Dose–Response Curves for Inhibition of COX-1 (Upper Panels) and COX-2 (Lower Panels) by Compounds 16 (Left Panels) and 25 (Right
Panels) and the Comparison with Aspirin
7.01 (2H, s), 2.38 (6H, s); Anal. Calcd for C16H12N2O4: C, 64.86; H, 4.08; N, 5.43; N, 9.01.
9.46. Found: C, 64.86; H, 4.33; N, 9.45.
5-Substituted phthalimides 7—10 were prepared according to the general
A mixture of 2 (1.21 g, 4.07 mmmol) and 10% Pd–C (118 mg) in AcOEt method.
(140 ml) was stirred under H2 for 3 h. After filtration, the filtrate was evapo-
7: Yellow prisms; mp 222—224 °C; 1H-NMR (CDCl3) 8.76 (1H, d,
rated, and the residue was purified by flash column chromatography Jϭ2.0 Hz), 8.66 (1H, dd, Jϭ8.1, 2.0 Hz), 8.14 (1H, t, Jϭ8.0 Hz), 7.09 (1H,
(AcOEt : hexane 1 : 2) to give 3 (1.03 g, 95%).
3: Yellow needles (CH2Cl2/hexane); mp 194—197 °C; H-NMR (CDCl3) N, 9.46. Found: C, 64.88; H, 4.22; N, 9.45.
7.47 (1H, t, Jϭ7.7 Hz), 7.24 (1H, d, Jϭ7.0 Hz), 7.02 (1H, s), 7.00 (2H, s),
s), 7.01 (2H, s), 2.39 (6H, s); Anal. Calcd for C16H12N2O4: C, 64.86; H, 4.08;
1
8: Yellow needles (CH2Cl2/hexane); mp 162 °C; 1H-NMR (CDCl3) 7.69
6.90 (1H, t, Jϭ8.2 Hz), 5.30 (2H, br s), 2.37 (6H, s); Anal. Calcd for (1H, d, Jϭ8.1 Hz), 7.11 (1H, d, Jϭ2.0 Hz), 7.01 (1H, s), 6.99 (2H, s), 6.87
C16H14N2O2: C, 72.16; H, 5.30; N, 10.52. Found: C, 71.96; H, 5.33; N, (1H, dd, Jϭ8.1, 2.2 Hz), 4.37 (2H, br s), 2.36 (6H, s); Anal. Calcd for
10.26.
C16H14N2O2: C, 72.16; H, 5.30; N, 10.52. Found: C, 72.05; H, 5.42; N,
Paraformaldehyde (75 mg, 2.5 mmol) and NaBH3CN (81 mg, 1.3 mmol) 10.44.
1
were added to a solution of 3 (66 mg, 0.25 mmol) in acetic acid (6 ml), and
9: Yellow needles (ether); mp 135—137 °C; H-NMR (CDCl3) 7.72 (1H,
the mixture was stirred for 4 h. The mixture was poured into 2 N NaOH, and
d, Jϭ8.4 Hz), 7.13 (1H, d, Jϭ8.4 Hz), 6.99 (3H, s), 6.83 (1H, dd, Jϭ8.5,
extracted with AcOEt. The organic layer was washed with brine, dried over 2.4 Hz), 3.13 (6H, s), 2.35 (6H, s); Anal. Calcd for C18H18N2O2: C, 73.45; H,
Na2SO4, and evaporated. The residue was purified by flash column chro- 6.16; N, 9.52. Found: C, 73.19; H, 6.30; N, 9.32.
1
matography (AcOEt : hexane 1 : 3) to give 4 (36 mg, 52%) and 5 (31 mg,
10: Colorless flakes (CH2Cl2/benzene); mp Ͼ300 °C; H-NMR (DMSO-
d6) 10.59 (1H, s), 8.25 (1H, s), 7.88 (2H, s), 7.06 (1H, s), 7.01 (2H, s), 2.31
42%).
4: Yellow plates (CH2Cl2/hexane); mp 179—181 °C; 1H-NMR (CDCl3) (6H, s) 2.31 (3H, s); Anal. Calcd for C18H16N2O3: C, 70.12; H, 5.23; N, 9.09.
7.55 (1H, dd, Jϭ8.5, 7.2 Hz), 7.16 (1H, d, Jϭ7.2 Hz), 7.01 (1H, s), 7.00 (2H, Found: C, 69.86; H, 5.37; N, 9.00.
s), 6.90 (1H, d, Jϭ8.6 Hz), 6.36 (1H, br s), 3.00 (3H, s) 2.36 (6H, s); Anal.
Calcd for C17H16N2O2: C, 72.84; H, 5.75; N, 9.99. Found: C, 72.72; H, 6.01; 3,5-xylidine (239 mg, 1.97 mmol) and a drop of acetic acid in THF (5 ml)
N, 9.84. was refluxed for 5 h. After evaporation, the residue was purified by flash col-
5: Yellow needles (CH2Cl2/hexane); mp 127—128 °C; H-NMR (CDCl3) umn chromatography (CH2Cl2) to give 11 (176 mg, 38%).
Isoindolinone 11 A mixture of o-phthalaldehyde (268 mg, 2.00 mmol),
1
7.55 (1H, dd, Jϭ8.4, 7.0 Hz), 7.37 (1H, d, Jϭ7.0 Hz), 7.13 (1H, d, Jϭ
11: Pale colored needles (ether/hexane); mp 136—139 °C; 1H-NMR
8.4 Hz), 7.01 (1H, s), 7.00 (2H, s), 3.13 (6H, s), 2.36 (6H, s); Anal. Calcd for (CDCl3) 7.92 (1H, d, Jϭ8.3 Hz), 7.59 (1H, t, Jϭ6.8 Hz), 7.52 (4H, m), 6.84
C18H18N2O2: C, 73.45; H, 6.16; N, 9.52. Found: C, 73.16; H, 6.26; N, 9.32.
(1H, s), 4.85 (2H, s), 2.37 (6H, s); Anal. Calcd for C16H15NO: C, 80.98; H,
A solution of 3 (67 mg, 0.25 mmol) and pyridine (0.5 ml) in acetic anhy- 6.37; N, 5.90. Found: C, 80.81; H, 6.49; N, 5.76.
dride (4 ml) was heated at 70 °C for 16 h. After cooling, the reaction mixture
7-Nitroisoindolinone 12 A solution of methyl 2-methyl-6-nitrobenzoate
was poured into water, and extracted with AcOEt. The organic layer was (196 mg, 1.00 mmol) and N-bromosuccinimide (396 mg, 2.22 mmol) in CCl4
washed with brine, dried over Na2SO4, and evaporated. The residue was pu- (10 ml) was refluxed for 7 h under an Ar atmosphere. The mixture was fil-
rified by flash column chromatography (AcOEt : hexane 1 : 3) to give 6
(72 mg, 93%).
tered, and the filtrate was evaporated. The residue was purified by flash
column chromatography (AcOEt : hexane 1 : 5) to give methyl 2-(bro-
6: Colorless needles (CH2Cl2/hexane); mp 155—157 °C; 1H-NMR momethyl)-6-nitrobenzoate (197 mg, 72%). A solution of methyl 2-(bro-
(DMSO-d6) 9.74 (1H, s), 8.50 (1H, d, Jϭ8.2 Hz), 7.83 (1H, d, Jϭ8.2 Hz), momethyl)-6-nitrobenzoate (2.50 g, 9.10 mmol), 3,5-xylidine (1.84 g,
7.62 (1H, d, Jϭ7.3 Hz), 7.08 (1H, s), 7.03 (2H, s), 2.49 (6H, s) 2.19 (3H, s); 15.2 mmol) and pyridine (1 ml) in ethanol (100 ml) was refluxed for 2 d.
Anal. Calcd for C18H16N2O3: C, 70.12; H, 5.23; N, 9.09. Found: C, 70.05; H,
After cooling, the mixture was poured into water. The precipitates was col-

September 2003
1101
lected, washed with water and ethanol, and recrystallized from acetone to s), 2.04 (3H, s); Anal. Calcd for C18H20N2O·1/6H2O: C, 76.30; H, 7.23; N,
give 12 (1.93 g, 75%).
9.89. Found: C, 76.36; H, 7.29; N, 9.81.
4-Nitroisoindolinone 21 was prepared according to the synthetic proce-
12: Pale yellow needles; mp 209—212 °C; 1H-NMR (DMSO-d6) 7.92
(2H, m), 7.86 (1H, m), 7.48 (2H, m), 6.86 (1H, s), 5.08 (2H, s), 2.30 (6H, s); dure for 12, and was converted to 22 and 23 according to the general
Anal. Calcd for C16H14N2O3: C, 68.07; H, 5.00; N, 9.92. Found: C, 67.90; H,
5.14; N, 9.64.
method.
21: Pale yellow needles (acetone); mp 258—260 °C; 1H-NMR (CDCl3)
12 was converted to 13—15 according to the general method.
8.45 (1H, d, Jϭ8.0 Hz), 8.27 (1H, d, Jϭ7.5 Hz), 7.75 (1H, t, Jϭ7.8 Hz), 7.51
13: Colorless needles (CH2Cl2/benzene); mp 158—159 °C; 1H-NMR (2H, s), 6.90 (1H, s), 5.31 (2H, s), 2.40 (6H, s); Anal. Calcd for C16H14N2O3:
(CDCl3) 7.42 (2H, s), 7.29 (1H, d, Jϭ7.7 Hz), 6.79 (1H, s), 6.72 (1H, d, C, 68.07; H, 5.00; N, 9.92. Found: C, 68.14; H, 5.18; N, 9.80.
Jϭ7.4 Hz), 6.57 (1H, d, Jϭ8.1 Hz), 5.32 (2H, br s), 4.74 (2H, s), 2.34 (6H,
s); Anal. Calcd for C16H16N2O: C, 76.16; H, 6.39; N, 11.10. Found: C, 76.19; (CDCl3) 7.47 (2H, s), 7.35 (1H, d, Jϭ7.0 Hz), 7.29 (1H, t, Jϭ7.5 Hz), 6.85
22: Colorless needles (CH2Cl2/hexane); mp 198—200 °C; 1H-NMR
H, 6.54; N, 11.03.
(1H, d, Jϭ7.9 Hz), 6.81 (1H, s), 4.64 (2H, s), 3.77 (2H, br s), 2.35 (6H, s);
14: Colorless needles (CH2Cl2/benzene); mp 197—199 °C; 1H-NMR Anal. Calcd for C16H16N2O: C, 76.16; H, 6.39; N, 11.10. Found: C, 76.11; H,
(CDCl3) 7.41 (2H, s), 7.37 (1H, t, Jϭ7.8 Hz), 6.78 (1H, s), 6.77 (1H, br s), 6.62; N, 11.06.
1
6.65 (1H, d, Jϭ7.3 Hz), 6.52 (1H, d, Jϭ8.1 Hz), 4.72 (2H, s), 2.92 (3H, d,
23: Colorless solid (methanol); mp 181—185 °C; H-NMR (CDCl3) 7.49
Jϭ5.1 Hz), 2.30 (6H, s); Anal. Calcd for C17H18N2O: C, 76.66; H, 6.81; N, (2H, s), 7.48 (1H, d, Jϭ7.9 Hz), 7.39 (1H, t, Jϭ7.9 Hz), 7.03 (1H, d,
10.52. Found: C, 76.68; H, 6.66; N, 10.33. Jϭ7.9 Hz), 6.84 (1H, s), 4.89 (2H, s), 2.96 (6H, s), 2.37 (6H, s); Anal. Calcd
15: Pale yellow prisms (CH2Cl2/benzene); mp 140—141 °C; 1H-NMR for C18H20N2O: C, 77.11; H, 7.19; N, 9.99. Found: C, 77.16; H, 7.29; N,
(CDCl3) 7.46 (2H, s), 7.41 (1H, t, Jϭ7.8 Hz), 6.94 (1H, d, Jϭ7.4 Hz), 6.88
(1H, d, Jϭ8.3 Hz), 6.80 (1H, s), 4.75 (2H, s), 3.04 (6H, s), 2.35 (6H, s);
Anal. Calcd for C18H20N2O: C, 77.11; H, 7.19; N, 9.99. Found: C, 76.96; H,
7.25; N, 9.90.
9.98.
4-Nitroisoindoline 24 and 4-(dimethylamino)isoindoline 27 were prepared
according to the synthetic procedure for 25.
24: Brown solid (CH2Cl2/hexane); mp 229—231 °C; 1H-NMR (CDCl3)
6- (16) and 5-Aminoisoindolinone (19) A mixture of 7 (1.199 g, 8.18 (1H, d, Jϭ8.2 Hz), 7.65 (1H, d, Jϭ7.2 Hz), 7.50 (1H, t, Jϭ7.8 Hz), 6.48
4.05 mmol) and Sn (9.21 g, 57.07 mmol) in ethanol (50 ml) and hydrochloric (1H, s), 6.39 (2H, s), 5.09 (2H, m), 4.72 (2H, m), 2.35 (6H, s); Anal. Calcd
acid (30 ml) was heated at 75 °C for 8 h. After cooling, the mixture was for C16H16N2O2·1/6H2O: C, 70.83; H, 6.07; N, 10.32. Found: C, 70.65; H,
poured into 2 N NaOH, and extracted with AcOEt. The organic layer was 5.99; N, 10.08.
washed with brine, dried over Na2SO4, and evaporated. The residue was pu-
rified by flash column chromatography (CH2Cl2 : AcOEt 4 : 1) to give 16 (DMSO-d6) 7.17 (1H, d, Jϭ8.6 Hz), 6.73 (1H, s), 6.69 (1H, d, Jϭ8.4 Hz),
27: Pale brown flakes (CH2Cl2/hexane); mp 115—116 °C; 1H-NMR
(312 mg, 31%) and 19 (392 mg, 38%).
6.30 (1H, s), 6.25 (2H, s), 4.48 (2H, s), 4.44 (2H, s), 2.89 (6H, s), 2.22 (6H,
s); Anal. Calcd for C18H22N2: C, 81.16; H, 8.32; N, 10.52. Found: C, 81.22;
16: Colorless plates (AcOEt); mp 197—200 °C; 1H-NMR (CDCl3) 7.46
(2H, s), 7.26 (1H, d, Jϭ8.1 Hz), 7.17 (1H, d, Jϭ2.2 Hz), 6.89 (1H, dd, H, 8.33; N, 10.46.
Jϭ8.1, 2.2 Hz), 6.82 (1H, s), 4.73 (2H, s), 3.86 (2H, br s), 2.36 (6H, s); Anal.
Calcd for C16H16N2O: C, 76.16; H, 6.39; N, 11.10. Found: C, 75.90; H, 6.50;
Acknowledgment The work described in this paper was partially sup-
ported by Grants-in-Aid for Scientific Research from The Ministry of Edu-
N, 10.99.
1
19: Colorless needles (AcOEt); mp 236—238 °C; H-NMR (CDCl3) 7.68 cation, Culture, Sports, Science and Technology, Japan.
(1H, d, Jϭ8.1 Hz), 7.46 (2H, s), 6.79 (1H, s), 6.73 (1H, dd, Jϭ8.2, 2.0 Hz),
6.70 (1H, s), 4.71 (2H, s), 4.06 (2H, br s), 2.35 (6H, s); Anal. Calcd for References
C16H16N2O: C, 76.16; H, 6.39; N, 11.10. Found: C, 75.87; H, 6.42; N, 10.94.
16 and 19 were alkylated according to the general method to afford 17 and
20, respectively.
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N, 9.95.
20: Colorless prisms (CH2Cl2/hexane); mp 211—213 °C; 1H-NMR
(CDCl3) 7.72 (1H, d, Jϭ8.6 Hz), 7.46 (2H, s), 6.76 (2H, m), 6.66 (1H, s),
4.72 (2H, s), 3.06 (6H, s), 2.34 (6H, s); Anal. Calcd for C18H20N2O: C,
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5-Nitroisoindolinone 18 and 5-nitroisoindoline 25 Borane in THF
(1 M, 30 ml) was added to a solution of 7 (2.98 g, 10.0 mmol) in 50 ml of
THF, and the mixture was refluxed for 16 h. After cooling, the mixture was
poured into 1 N HCl, stirred for 1 h, and extracted with AcOEt. The organic
solution was washed with brine, and dried over MgSO4. After evaporation, 10) Miyachi H., Kato M., Kato F., Hashimoto Y., J. Med. Chem., 41,
the crude product was purified by flash column chromatography
(AcOEt/hexane 1 : 10) to give 18 (0.17 g, 6%) and 25 (1.71 g, 67%).
18: Yellow needles (CH2Cl2/hexane); mp 205—207 °C; 1H-NMR
263—265 (1998).
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Jϭ7.8 Hz), 7.56 (2H, s), 6.86 (1H, s), 5.39 (2H, s), 2.08 (6H, s); Anal. Calcd
for C16H14N2O3: C, 68.07; H, 5.00; N, 9.92. Found: C, 67.80; H, 5.07; N,
9.79.
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25: Brown solid (CH2Cl2/hexane); mp 171—173 °C; 1H-NMR (CDCl3)
8.20 (2H, m), 7.48 (1H, d, Jϭ8.8 Hz), 6.51 (1H, s), 6.37 (2H, s), 4.74 (4H,
s), 2.34 (6H, s); Anal. Calcd for C16H16N2O2·1/6H2O: C, 70.83; H, 6.07; N,
10.32. Found: C, 70.93; H, 6.05; N, 10.23.
25 was converted to 26 and 28 according to the general method.
26: Brown prisms (CH2Cl2/hexane); mp 140.5—142.5 °C; 1H-NMR 16) Kita T., Takahashi H., Hashimoto Y., Biol. Pharm. Bull., 24, 860—862
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7.70; N, 11.62.
1
28: Brown prisms (CH2Cl2/hexane); mp 256—259 °C; H-NMR (DMSO-
d6) 9.96 (1H, s), 7.68 (1H, s), 7.42 (1H, dd, Jϭ8.2, 1.5 Hz), 7.28 (1H, d, 19) Smith W. L., Garavito R. M., DeWitt D. L., J. Biol. Chem., 271,
Jϭ8.1 Hz), 6.31 (1H, s), 6.27 (2H, s), 4.51 (2H, s), 4.49 (2H, s), 2.22 (6H, 33157—33160 (1996).

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Vol. 51, No. 9
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