2-Acyl-tetrahydroisoquinoline-3-carboxylic Acids: Lead compounds with triple actions, peroxisome proliferator-activated receptor α/γ agonist and protein-tyrosine phosphatase 1B inhibitory activities

Article abstract of DOI:10.1248/cpb.59.876

2-Acyl-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and biologically evaluated. (S)-2-(2,4-Hexadienoyl)-7-[2-(5-methyl- 2-phenyloxazol-4-yl)ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (14) showed peroxisome proliferat

Full text of DOI:10.1248/cpb.59.876

876
Note
Chem. Pharm. Bull. 59(7) 876—879 (2011)
Vol. 59, No. 7
2-Acyl-tetrahydroisoquinoline-3-carboxylic Acids: Lead Compounds with
a g
Triple Actions, Peroxisome Proliferator-Activated Receptor /
Agonist and Protein-Tyrosine Phosphatase 1B Inhibitory Activities
Kazuya OTAKE, Satoru AZUKIZAWA, Kenji TAKAHASHI, Masaki FUKUI, Michiko SHIBABAYASHI,
Hikaru KAMEMOTO, Masayasu KASAI, and Hiroaki SHIRAHASE*
Research Laboratories, Kyoto Pharmaceutical Industries, Ltd.; 38, Nishinokyo Tsukinowa-cho, Nakagyo-ku, Kyoto
604–8444, Japan. Received February 10, 2011; accepted April 1, 2011
2-Acyl-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and biologically evaluated. (S)-
2-(2,4-Hexadienoyl)-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid
(14) showed peroxisome proliferator-activated receptor g (PPARg) and PPARa agonist activities and protein-
tyrosine phosphatase 1B (PTP-1B) inhibitory activities. PPARg agonist activity of 14 was comparable to that of
rosiglitazone, and PTP-1B inhibitory activity was about 10-fold weaker than that of ertiprotafib, a PTP-1B
inhibitor. Compound 14 showed high oral absorption in rats and potent hypoglycemic effects in KK-Ay mice. In
conclusion, 14 would be an excellent lead compound for a new type of anti-diabetic drug with triple actions.
Key words peroxisome proliferator-activated receptor; diabetes; hypoglycemic effect; tetrahydroisoquinoline derivative;
protein-tyrosine phosphatase 1B
Thiazolidinedione derivatives (troglitazone, pioglitazone ships in KY-021 derivatives revealed that 2-benzyl but not
and rosiglitazone) improve insulin resistance via peroxisome cyclohexylmethyl, phenyl, benzoyl, or hexyl was the most
proliferator-activated receptor g (PPARg) activation, and suitable moiety for interaction with PPARg protein; however,
have been used as anti-diabetic drugs; however, troglitazone derivatives with aliphatic acyl chain at the 2-position have
was voluntarily withdrawn from the market because of fetal not yet been synthesized.6) In the present study, a 2-benzyl
hepatoxicities, and both pioglitazone and rosiglitazone are group of KY-021 was changed to a hexanoyl, hexenoyl and
carefully used because of the risks of fluid expansion, con- hexynoyl chain, and the PPAR agonist activities and protein-
gestive heart failure, obesity and/or bone fracture.1—3) Other tyrosine phosphatase 1B (PTP-1B) inhibitory activities were
than thiazolidinedione derivatives, a great number of non-thi- evaluated. Among the 2-acyl derivatives, a lead compound
azolidinedione derivatives have been reported as candidates 14 for a new type of anti-diabetic drug with PPARa/g ago-
for safer and more efficacious PPARg agonists than thiazol- nists and PTP-1B inhibitory activity was found.
idinedione derivatives. Carboxylate derivatives with PPARg
Chemistry The general approach to the synthesis of (S)-
and PPARa agonist activities were expected to exert excel- 2-substituted-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-
lent anti-diabetic activities through the synergistic effects of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives
PPARg-mediated enhancement of insulin sensitivity and is outlined in Chart 1. Compound 1 and 2 were prepared ac-
PPARa-mediated reduction of plasma lipids.4) PPARg acti- cording to the previously reported procedure.6)
vation may increase body weight gain via adipocyte differen-
Acylation of 1 and 2 afforded 2-acyl tetrahydroisoquino-
tiation, whereas PPARa activation may decrease body weight line derivatives 3—8, which were treated with aqueous LiOH
gain via increased energy expenditure; however, PPARa/g to give tetrahydroisoquinoline-3-carboxylic acid derivatives
dual agonists, ragaglitazar, muraglitazar, tesaglitazar and 9—14. As the free form of compound 14 was unstable, 14
imiglitazar showed carcinogenicity, cardiovascular or hepatic was isolated as a tert-butylamine salt.
risks, and their clinical development was discontinued.3,4)
Based on this background, newer PPARg agonists with Results and Discussion
different chemical and biological properties from those of the
We have previously reported a novel tetrahydroisoquino-
reported compounds are needed to be developed. We have re- line-based PPARg agonist, KY-021, which showed more effi-
ported a novel tetrahydroisoquinoline-based PPARg agonist, cacious and safer anti-diabetic effects than farglitazar.5,6)
KY-021, which was considered to be a more efficacious and However, simple PPARg agonists, even KY-021, showed
safer candidate for an anti-diabetic drug than farglitazar, and fluid retention and body weight gain at high doses; therefore,
proposed that a tetrahydroisoquinoline ring is a useful scaf- it is important to find a new PPARg agonist with distinct
fold for PPAR agonists.5,6) The structure–activity relation- chemical and biological properties. Although a compound
(i) various carboxylic acids, EDC, CH2Cl2; (ii) hexanoyl chloride, Et3N, CH2Cl2; (iii) LiOH aq., THF-MeOH; a) tert-BuNH2 salt by tert-BuNH2 in MeOH-i-Pr2O.
Chart 1. Synthesis of (S)-2-Substituted-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid Derivatives
∗ To whom correspondence should be addressed. e-mail: shirahase@kyoto-pharm.co.jp
© 2011 Pharmaceutical Society of Japan

July 2011
877
Table 1. Molecular Weight, log D7.0, PPARg and PPARa Transactivation Effects, PTP-1B Inhibition, Plasma Concentration in Male Rats and Hypo-
glycemic Effects in Male KK-Ay Mice of 1,2,3,4-Tetrahydroisoquinoline-3-carboxylic Acid Derivatives
Plasma concentratione)
KK-Ay mouse f )
(10 mg/kg, 4 d)
PPARgb)
PPARab)
PTP-1Bb)
(10 mg/kg p.o.)
Compound
R
Mol.Wt.a) log D7.0
EC50
(nM)
Maxc)
(%)
EC50
Maxd)
(%)
IC50
Cmax
AUC
Glucose
(nM)
142
809
477
(mM)
(mg/ml)
(mg·h/ml)
% decrease
9
476.56
474.55
474.55
2.6
2.1
2.2
22
103.7
82.0
86.3
74.1
82.7
68.0
9.0
8.9
7.9
5.9ꢀ2.5
3.4ꢀ0.8
8.7ꢀ1.7
10.2ꢀ4.1
6.3ꢀ0.1
38
10
11
96
24
28
21.6ꢀ6.0
51**
12
13
474.55
472.53
472.53
462.58
468.54
2.1
1.9
2.0
4.3
3.2
112
19
84.4
92.3
90.9
97.1
91.6
377
93
49.5
72.3
8.9
9.2
4.3ꢀ1.4
8.5ꢀ1.2
22
13.8ꢀ2.7
38.1ꢀ6.7
58**
60**
ꢁ1
14
164
67
378
40
87.0
9.4
39.1ꢀ14.0 176.6ꢀ45.9
15
113.0
50.7
52.5
8.6ꢀ1.4
2.1ꢀ0.3
N.T.g)
N.T.g)
N.T.g)
13.9ꢀ2.9
12.6ꢀ1.2
N.T.g)
N.T.g)
N.T.g)
KY-021
24
184
83.6
64.1
45**
Pioglitazone
Rosiglitazone
Ertiprotafib
356.44
357.43
559.51
N.T.g)
N.T.g)
N.T.g)
671
138
3194
103.6
127.9
77.9
ꢂ10000
ꢂ10000 125.0
ꢂ10000
61.0
ꢂ100
1.6
41*
38
—
N.T.g)
a) Free form. b) nꢃ2. c) The activation level induced by farglitazar (10ꢁ7 M) was taken as 100%. d) The activation level induced by Wy-14643 (10ꢁ5 M) was taken as
100%. e) Plasma concentration in male rats, nꢃ4. f ) nꢃ5, ∗ pꢄ0.05, ∗∗ pꢄ0.01, vs. control, Student’s t-test. g) Not tested.
with 2-benzoyl moiety has been synthesized and known to be action with PPARa protein, while the 2-acyl moieties were
much weaker than KY-021 with 2-benzyl moiety, compounds considered to have opposite effects on the interaction with
with an aliphatic acyl chain at the 2-position have not been PPARg protein, dependent on the position of the double or
synthesized. In the present study, derivatives of KY-021 with triple bond.
a hexanoyl, hexenoyl or hexynoyl chain were synthesized and
their log D7.0 and biological properties were compared to KY- plasma glucose levels in KK-Ay mice: their PPARg agonist
021 and the derivative with a hexyl chain (15) (Table 1). activity, Cmax and AUC were comparable to or higher than
Among these derivatives, 9, 11 and 13 markedly reduced
Re-evaluation of KY-021 found that it has about 7-fold those of KY-021. On the other hand, compound 10 and 12
weaker PPARa agonist activitiy than PPARg agonist activity. failed to reduce plasma glucose levels: their PPARg agonist
Compound 15 was more lipophilic than KY-021 (log D7.0 4.3 activity and AUC were lower than those of KY-021, although
vs. 3.2), and showed about 3-fold weaker PPARg agonist ac- their Cmax slightly increased. Interestingly, 14 showed 8-fold
tivity and about 4-fold stronger PPARa agonist activity than weaker PPARg agonist activity but 20-fold and 13-fold
KY-021: it is therefore a dual agonist with comparable higher Cmax and AUC, respectively, in comparison with KY-
PPARa and PPARg agonist activities. Unlike KY-021, 15 021, and thus markedly lowered plasma glucose levels. The
failed to decrease plasma glucose levels in KK-Ay mice, PPARg agonist activity of 14 was comparable to that of
probably due to low oral absorption. Although oral absorp- rosiglitazone and higher than that of pioglitazone. Further-
tion of 15 in mice was not determined, its Cmax was about 4- more, 14 showed about 2-fold weaker PPARa agonist activ-
fold higher than, but area under curve (AUC) was still com- ity than its PPARg agonist activity: it is therefore considered
parable to that of KY-021 in rats. Compound 15 may have to be a bioavailable PPARa/g dual agonist.
been easily metabolized in KK-Ay mice.
PPARg agonists such as rosiglitazone and pioglitazone
The derivatives with a hexanoyl, hexenoyl and hexynoyl have been clinically used as anti-diabetic drugs with insulin-
group at the 2-position showed lower lipophilicity than KY- sensitivity-enhancing activity, however, they have adverse ef-
021 and 15. The PPARg agonist activities of derivatives with fects, including risks for fluid retention, congestive heart fail-
a hexanoyl, 2-hexenoyl and 2-hexynoyl group (9, 11, 13) ure, body weight gain and bone fracture.1—3) PPARa agonists
were comparable to that of KY-021 and higher than that of such as fibrates have also been reported to have anti-diabetic
15, while the activities of derivatives with a 3-hexenoyl, 5- effects probably via improvement of dyslipidemia, and have
hexenoyl and 2,4-hexadienoyl group (10, 12, 14) were lower the potential to reduce body weight.7) Therefore, a number of
than that of KY-021 and 15. PPARa agonist activity was de- PPARa/g dual agonists have been reported: muraglitazar and
creased in all 2-acyl derivatives in comparison with 15, indi- tesaglitazar showed excellent anti-diabetic effects; however,
cating that the 2-acyl structure was less preferable for inter- their development was discontinued due to their cardiovascu-

878
Vol. 59, No. 7
lar adverse effects.3) Another approach to insulin resistance,
PTP-1B inhibition, has been a focus because PTP-1B hy-
drolyzes a phosphorylated tyrosine residue of insulin recep-
tor, resulting in cancellation of the insulin signal.8—10) It has
been reported that PTP-1B is over-expressed in insulin-re-
sistant animals and PTP-1B inhibitors enhance insulin sensi-
tivity. Furthermore, PTP-1B down-regulates a leptin signal
and is involved in obesity: PTP-1B inhibitors may exert anti-
obesity effects via hypophagia.10) Thus, PTP-1B inhibitors
have been expected to be novel insulin-sensitivity enhancers
without body weight gain: however, none of the inhibitors
have been successfully developed. PPARg agonist with PTP-
1B inhibitory activity would be a novel safe and efficacious
insulin-sensitivity enhancer.
evaporated under reduced pressure, and the obtained residue was purified by
column chromatography to give 4 (493 mg, 99%) as a solid. 1H-NMR
(CDCl3) d: 0.93 (3H, t, Jꢃ6.6 Hz), 1.80—2.15 (2H, m), 2.36 (3H, s), 2.80—
3.35 (6H, m), 3.59 (3H, s), 4.00—4.30 (2H, m), 4.40—5.10 (3H, m), 5.30—
5.70 (2H, m), 6.50—7.10 (3H, m), 7.30—7.60 (3H, m), 7.80—8.10 (2H, m).
Compounds 5—8 were prepared according to the procedure for the syn-
thesis of 4.
Methyl (S)-2-[(2E)-Hexenoyl]-7-[2-(5-methyl-2-phenyloxazol-4-yl)-
ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (5) 1H-NMR
(CDCl3) d: 0.80—1.05 (3H, m), 1.10—1.90 (2H, m), 2.00—2.50 (5H, m),
2.80—3.20 (4H, m), 3.59 (3H, s), 4.00—4.20 (2H, m), 4.50—5.10 (3H, m),
5.35—5.60 (1H, m), 6.00—7.10 (4H, m), 7.30—7.60 (3H, m), 7.80—8.10
(2H, m). IR (Nujol) cmꢁ1: 2957, 1740, 1660, 1622, 1554, 1506.
Methyl (S)-2-(5-Hexenoyl)-7-[2-(5-methyl-2-phenyloxazol-4-yl)-
ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (6) 1H-NMR
(CDCl3) d: 1.60—2.00 (2H, m), 2.00—2.30 (2H, m), 2.37 (3H, s), 2.45 (2H,
t, Jꢃ7.0 Hz), 2.90—3.30 (4H, m), 3.59 (3H, s), 4.22 (2H, t, Jꢃ6.7 Hz),
The 2-acyl derivatives synthesized all have weak PTP-1B 4.40—5.20 (4H, m), 5.30—6.10 (2H, m), 6.60—6.90 (2H, m), 7.04 (1H, d,
Jꢃ8.2 Hz), 7.20—7.60 (3H, m), 7.80—8.20 (1H, m).
inhibitory activity, while KY-021, 15, rosiglitazone and pi-
oglitazone showed little effect on PTP-1B activity. The activ-
ities of 2-acyl derivatives may not have contributed to their
Methyl (S)-2-(2-Hexynoyl)-7-[2-(5-methyl-2-phenyloxazol-4-yl)-
ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (7) 1H-NMR
(CDCl3) d: 0.90—1.10 (3H, m), 1.60—1.90 (2H, m), 2.25—2.50 (5H, m),
hypoglycemic effects, because the activity was about 10-fold
weaker than ertiprotafib reported as a PTP-1B inhibitor.
However, compound 14 showed an extremely high Cmax at
10 mg/kg (per os (p.o.)) in rats, which was higher than its
IC50 value for PTP-1B inhibition, suggesting that 14 exerts
the hypoglycemic effect, at least in part, via PTP-1B inhibi-
tion. Repeated administration of 14 at 100 mg/kg for 4 weeks
(Cmax after final administration: 148 mg/ml) had no adverse
effects in male rats, while KY-021 and farglitazar increased
of blood volume, heart and white adipose tissue weight.5,6)
In conclusion, tetrahydroisoquinoline derivatives with
hexanoyl, 2-hexenoyl, 2-hexynoyl and 2,4-hexadienoyl group
(9, 11, 13, 14) were PPARg agonists with potent anti-diabetic
activities, and 14 was a highly bioavailable PPARa/g dual
agonist with weak PTP-1B inhibitory activity. Compound 14
2.96 (2H, t, Jꢃ6.6 Hz), 3.00—3.30 (2H, m), 3.61, 3.63 (total 3H, s, s)
4.10—4.30 (2H, m), 4.35—5.20 (2H, m), 5.25—5.50 (1H, m), 6.60—6.90
(2H, m), 7.05 (1H, d, Jꢃ8.2 Hz), 7.30—7.60 (3H, m), 7.80—8.05 (2H, m).
IR (Nujol) cmꢁ1: 2239, 1740, 1634, 1587, 1555, 1506.
Methyl (S)-2-[(2E,4E)-Hexadienoyl]-7-[2-(5-methyl-2-phenyloxazol-4-
yl)ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (8) 1H-NMR
(CDCl3) d: 1.85 (3H, d, Jꢃ5.0 Hz), 2.36 (3H, s), 2.96 (2H, t, Jꢃ6.8 Hz),
3.00—3.40 (2H, m), 3.59 (3H, s), 4.22 (2H, t, Jꢃ6.8 Hz), 4.50—5.65 (3H,
m), 5.90—6.50 (3H, m), 6.55—6.85 (2H, m), 7.04 (1H, d, Jꢃ8.4 Hz),
7.15—7.60 (4H, m), 7.80—8.15 (2H, m). IR (neat) cmꢁ1: 1740, 1653, 1626,
1601, 1555, 1506.
(S)-2-Hexanoyl-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-1,2,3,4-
tetrahydroisoquinoline-3-carboxylic Acid (9) To a solution of 3 (1.02 g,
2.02 mmol) in tetrahydrofuran (THF)–MeOH (3 : 1, 10 ml) was added 1.0 M
aqueous lithium hydroxide solution (6.00 ml, 6.0 mmol), and the mixture
was stirred at room temperature for 4 h. The solvent was evaporated under
reduced pressure, and the obtained residue was acidified with citric acid.
The precipitated solid was collected by filtration to give 9 (0.56 g, 58%) as a
would be utilized as a lead compound for a novel type of white solid. mp 129—131 °C. 1H-NMR (CDCl3) d: 0.75—1.00 (3H, m),
1.10—1.90 (6H, m), 2.32 (3H, s), 2.35—2.50 (2H, m), 2.70—3.10 (4H, m),
4.07 (2H, t, Jꢃ5.9 Hz), 4.60 (2H, s), 5.40—5.60 (1H, m), 6.60—6.80 (2H,
anti-diabetic drug with triple actions, PPARa/g agonist and
PTP-1B inhibitory activities.
m), 7.05 (1H, d, Jꢃ8.6 Hz), 7.35—7.65 (3H, m), 7.75—8.10 (2H, m). IR
(Nujol) cmꢁ1: 1742, 1572. MS m/z: 477 [MꢅH]ꢅ. Anal. Calcd for
Experimental
C28H32N2O5·0.5H2O: C, 69.26; H, 6.85; N, 5.77. Found: C, 69.25; H, 6.69;
N, 5.73.
Compounds 10—13 were prepared according to a procedure for the syn-
thesis of 9.
General Melting points were measured on a Yamato MP-21 melting
point apparatus and are uncorrected. Proton nuclear magnetic resonance
(1H-NMR) spectra were obtained on a Hitachi FT-NMR R-1900 NMR spec-
trometer, using tetramethylsilane (TMS) as an internal standard. Infrared
(IR) spectra were recorded with a Shimadzu FT-IR8200PC spectrometer.
Mass spectra were obtained on an Applied Biosystems API2000 QTRAP
LC/MS/MS system. Daisogel No.1001W (70—230 mesh, Daiso) was used
for column chromatography. TLC was performed on pre-coated TLC plates
with 60F254 (Merck).
(S)-2-[(3E)-Hexenoyl]-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-
1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid (10) A white solid, mp
1
136.5—138.5 °C. H-NMR (CDCl3) d: 0.94 (3H, t, Jꢃ7.5 Hz), 1.88—2.10
(2H, m), 2.32 (3H, s), 2.70—3.50 (6H, m), 3.90—4.30 (2H, m), 4.35—5.10
(3H, m), 5.30—5.75 (2H, m), 6.50—7.10 (3H, m), 7.30—7.60 (3H, m),
7.70—8.10 (2H, m), 8.50—9.10 (1H, br). IR (Nujol) cmꢁ1: 2854, 1741,
1641, 1610, 1575, 1554, 1506. MS m/z: 475 [MꢅH]ꢅ. Anal. Calcd for
C28H30N2O5·0.5H2O: C, 69.55; H, 6.46; N, 5.79. Found: C, 69.69; H, 6.29;
N, 5.71.
Ethyl (S)-2-Hexanoyl-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-
1,2,3,4-tetrahydroisoquinoline-3-carboxylate (3) To a solution of 1
(1.00 g, 2.55 mmol) in CH2Cl2 (10 ml) were added triethylamine (0.51 ml,
3.7 mmol) and hexanoyl chloride (0.41 ml, 3.0 mmol) under ice-cooling, and
the mixture was stirred at the same temperature for 15 min. The reaction
mixture was washed with water and brine and dried over Na2SO4. The sol-
vent was evaporated under reduced pressure, and the obtained residue was
(S)-2-[(2E)-Hexenoyl]-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-
1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid (11) A white solid, mp
136.5—138.5 °C. 1H-NMR (CDCl3) d: 0.75—1.05 (3H, m), 1.10—1.80
(2H, m), 2.00—2.50 (5H, m), 2.70—3.40 (4H, m), 3.90—4.10 (2H, m),
4.35—5.10 (3H, m), 5.30—5.60 (1H, m), 6.00—7.10 (4H, m), 7.30—7.60
(3H, m), 7.70—8.00 (2H, m), 8.20—8.70 (1H, br). IR (Nujol) cmꢁ1: 2854,
1740, 1652, 1612, 1552, 1506. MS m/z: 475 [MꢅH]ꢅ. Anal. Calcd for
C28H30N2O5·0.5H2O: C, 69.55; H, 6.46; N, 5.79. Found: C, 69.64; H, 6.29;
N, 5.80.
1
purified by column chromatography to give 3 (1.02 g, 84%) as an oil. H-
NMR (CDCl3) d: 0.70—1.90 (12H, m), 2.20—2.60 (5H, m), 2.95 (2H, t,
Jꢃ6.8 Hz), 3.10—3.20 (2H, m), 4.04 (2H, q, Jꢃ7.0 Hz), 4.22 (2H, t,
Jꢃ6.8 Hz), 4.63 (2H, s), 5.45 (1H, dd, Jꢃ5.4, 4.0 Hz), 6.60—6.90 (2H, m),
7.04 (1H, d, Jꢃ8.1 Hz), 7.30—7.50 (3H, m), 7.80—8.10 (2H, m). IR (neat)
cmꢁ1: 1736, 1653, 1587, 1506.
Methyl (S)-2-[(3E)-Hexenoyl]-7-[2-(5-methyl-2-phenyloxazol-4-yl)-
ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (4) To a solution
of 2 (400 mg, 1.02 mmol) in CH2Cl2 (4 ml) were added 3-hexenoic acid
(0.18 ml, 1.52 mmol) and EDC (330 mg, 1.72 mmol) under ice-cooling, and
the mixture was stirred at room temperature for 1 h. The reaction mixture
was washed with water and brine, and dried over Na2SO4. The solvent was
(S)-2-(5-Hexenoyl)-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-
1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid (12) A white solid, mp
1
78—81 °C. H-NMR (DMSO-d6) d: 1.60—2.00 (2H, m), 2.00—2.30 (2H,
m), 2.32 (3H, s), 2.43 (2H, t, Jꢃ7.3 Hz), 2.80—3.40 (4H, m), 4.06 (2H, t,
Jꢃ6.3 Hz), 4.30—5.20 (4H, m), 5.30—6.10 (2H, m), 6.50—6.80 (2H, m),
7.04 (1H, d, Jꢃ8.2 Hz), 7.20—7.60 (3H, m), 7.80—8.20 (1H, m). IR (Nujol)
:
cmꢁ1 1624, 1508, 1460. MS m/z: 475 [MꢅH]ꢅ. Anal. Calcd for

July 2011
879
C28H30N2O5·0.5H2O: C, 69.55; H, 6.46; N, 5.79. Found: C, 69.48; H, 6.32;
N, 5.72.
(S)-2-(2-Hexynoyl)-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-
Physicochemical and Biological Evaluations Log D7.0, plasma concen-
trations and hypoglycemic effects of test compounds were determined ac-
cording to the methods reported previously.6) Animal experiments were con-
ducted according to the guidelines for animal experiments of our institute
1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid (13) A white solid, mp
1
78—81 °C. H-NMR (DMSO-d6) d: 0.90—1.05 (3H, m), 1.35—1.80 (2H, and the Guidelines for Animal Experimentation approved by the Japanese
m), 2.30—2.60 (5H, m), 2.91 (2H, t, Jꢃ6.6 Hz), 3.00—3.30 (2H, m), 4.18 Association of Laboratory Animal Science. PTP-1B activity was determined
(2H, t, Jꢃ6.6 Hz), 4.35—5.30 (3H, m), 6.65—7.00 (2H, m), 7.11 (1H, d, using human PTP-1B as an enzyme and p-nitrophenyl phosphate as a sub-
Jꢃ7.9 Hz), 7.40—7.70 (3H, m), 7.80—8.10 (2H, m). IR (Nujol) cmꢁ1
2235, 1732, 1634, 1583, 1553, 1506. MS m/z: 473 [MꢅH]ꢅ. Anal. Calcd for
:
strate. PPARg and PPARa agonist activities were determined in COS-1
cells, which were transiently transfected with the PPAR-responsive (luci) re-
C28H28N2O5·0.5H2O: C, 69.84; H, 6.07; N, 5.82. Found: C, 69.89; H, 6.03; porter construct, and pCMV-PPARg or pCMV-PPARa using the Lonza Nu-
N, 5.83. cleofector II Device.
(S)-2-[(2E,4E)-Hexadienoyl]-7-[2-(5-methyl-2-phenyloxazol-4-yl)-
ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid tert-Butyl- References
amine Salt (14) To a solution of 8 (3.25 g, 6.68 mmol) in THF–MeOH
(3 : 1, 80 ml) was added 1.0 M aqueous lithium hydroxide solution (20 ml,
20 mmol), and the mixture was stirred at room temperature for 1 h. The mix-
ture was acidified with 6 M HCl, and the solvent was evaporated under re-
duced pressure. The obtained residue was extracted with AcOEt, and the or-
ganic layer was washed with water and brine, then dried over Na2SO4. The
solvent was evaporated under reduced pressure to give a free form of 14,
which was dissolved in MeOH (30 ml). After dropwise addition of tert-bu-
tylamine (0.8 ml, 7.6 mmol), diisopropyl ether (300 ml) was added, and the
mixture was stirred under ice-cooling for 1.5 h. The precipitated crystals
were collected by filtration to give 14 (3.03 g, 83%) as a white solid. mp
1) Krische D., West. J. Med., 173, 54—57 (2000).
2) Shah P., Mudaliar S., Expert Opin. Drug Saf., 9, 347—354 (2010).
3) Cho N., Momose Y., Curr. Top. Med. Chem., 8, 1483—1507 (2008).
4) Henke B. R., J. Med. Chem., 47, 4118—4127 (2004).
5) Azukizawa S., Kasai M., Takahashi K., Kunishiro K., Yoshimi A., Shi-
rahase H., Yakugaku Zasshi, 124 (Suppl 3), 195—196 (2004).
6) Azukizawa S., Kasai M., Takahashi K., Miike T., Kunishiro K., Kanda
M., Mukai C., Shirahase H., Chem. Pharm. Bull., 56, 335—345
(2008).
7) Guerre-Millo M., Gervois P., Raspé E., Madsen L., Poulain P., Derudas
B., Herbert J. M., Winegar D. A., Willson T. M., Fruchart J. C., Berge
R. K., Staels B., J. Biol. Chem., 275, 16638—16642 (2000).
8) Lee S., Wang Q., Med. Res. Rev., 27, 553—573 (2007).
9) Zhang S., Zhang Z. Y., Drug Discov. Today, 12, 373—381 (2007).
1
141—143 °C. H-NMR (CDCl3) d: 0.98 (9H, s), 1.60—2.00 (3H, m), 2.36
(3H, s), 2.70—3.40 (4H, m), 4.17 (2H, t, Jꢃ6.4 Hz), 4.25—5.20 (3H, m),
5.70—7.15 (10H, m), 7.15—7.60 (3H, m), 7.80—8.15 (2H, m). IR (Nujol)
cmꢁ1: 2743, 2637, 2550, 2210, 1624, 1599, 1587, 1556, 1506. MS m/z: 546 10) Koren S., Fantus I. G., Best Pract. Res. Clin. Endocrinol. Metab., 21,
[MꢅH]ꢅ. Anal. Calcd for C28H28N2O5·C4H11N·0.2H2O: C, 69.97; H, 7.23;
621—640 (2007).
N, 7.65. Found: C, 69.81; H, 7.09; N, 7.63.