2,3,5-Trisubstituted pyridines as selective AKT inhibitors. Part II: Improved drug-like properties and kinase selectivity from azaindazoles

Article abstract of DOI:10.1016/j.bmcl.2009.11.060

A novel series of AKT inhibitors containing 2,3,5-trisubstituted pyridines with novel azaindazoles as hinge binding elements are described. Among these, the 4,7-diazaindazole compound 2c has improved drug-like properties and kinase selectivity than those of indazole 1, and displays greater than 80% inhibition of GSK3β phosphorylation in a BT474 tumor xenograft model in mice.

Full text of DOI:10.1016/j.bmcl.2009.11.060

Bioorganic & Medicinal Chemistry Letters 20 (2010) 679–683
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
2,3,5-Trisubstituted pyridines as selective AKT inhibitors. Part II: Improved
drug-like properties and kinase selectivity from azaindazoles
a
a
a
a
a
b
Hong Lin a, , Dennis S. Yamashita , Jin Zeng , Ren Xie , Sharad Verma , Juan I. Luengo , Nelson Rhodes ,
Shuyun Zhang b, Kimberly A. Robell b, Anthony E. Choudhry b, Zhihong Lai b, Rakesh Kumar b,
Elisabeth A. Minthorn c, Kristin K. Brown d, Dirk A. Heerding a
*
a Oncology Medicinal Chemistry, GlaxoSmithKline,1250 S. Collegeville, Rd., Collegeville, PA 19426, United States
b Oncology Biology, GlaxoSmithKline,1250 S. Collegeville, Rd., Collegeville, PA 19426, United States
c Oncology Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, 1250 S. Collegeville, Rd., Collegeville, PA 19426, United States
d Molecular Discovery Research, GlaxoSmithKline,1250 S. Collegeville, Rd., Collegeville, PA 19426, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel series of AKT inhibitors containing 2,3,5-trisubstituted pyridines with novel azaindazoles as
hinge binding elements are described. Among these, the 4,7-diazaindazole compound 2c has improved
drug-like properties and kinase selectivity than those of indazole 1, and displays greater than 80% inhi-
bition of GSK3b phosphorylation in a BT474 tumor xenograft model in mice.
Received 25 September 2009
Revised 11 November 2009
Accepted 16 November 2009
Available online 20 November 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
AKT kinase inhibitors
Selectivity
Azaindazole
Table 1
Small-molecule protein kinase inhibitors have emerged as a
promising class of cancer therapeutics. As most of these molecules
target the relatively conserved ATP binding pocket, achieving ki-
nase selectivity is a difficult task, especially among the kinases in
the same superfamily.1 The identification of more selective kinase
inhibitors is an important step towards avoiding the potentially
unintended biological consequences of an unselective kinase inhib-
itor. In addition, these selective agents can function as critical tools
to facilitate our understanding of the signaling pathways regulated
by these kinases.
Biological and developability data of compound 1
O
H
N
N
N
H
N
NH2
O
1
Serine/threonine kinases AKT1/2/3 belong to the AGC super-
family and have been implicated as key mediators of cell prolifer-
ation, metabolism, survival and inhibition of apoptosis.2 During the
search for a potent, selective and novel kinase inhibitor of AKT, we
identified compound 1.3 As shown in Table 1, compound 1 is a po-
tent pan-AKT inhibitor that is selective against ROCK1, a close rel-
ative of AKT in AGC superfamily. Compound 1 was also potent in
cellular mechanistic and proliferation assays,4 displaying IC50 val-
a
IC50
Cellular activity
(lM)
Enzyme
Kinase selectivity
CYP450
CYP1A2 50
0.50
AKT1
AKT2
AKT3
0.001
0.012
0.001
pGSK3bb
BT474c
LNCaPc
HFFc
0.50
ROCK1
P70S6K
PAK1
PDK1
PKA
1.58
0.34
0.19
5.50
0.007
0.031
0.050
0.001
0.025
CYP2C9
CYP2C19
CYP2D6
CYP3A4
2.0
5.0
0.050
ues of 0.34 lM and 0.19 lM respectively in proliferation assays
RSK
in BT474 (breast) and LNCaP (prostate) cells, which harbor consti-
tutively activated AKT, while showing greatly diminished potency
in HFF cells, which do not contain constitutively active AKT.5 Fur-
thermore, compound 1 inhibited GSK3b phosphorylation in the
a
b
c
n P 2.
Inhibition of phosphorylation of GSK3b in BT474 cells.
Inhibition of proliferation.
BT474 cell line (IC50 = 0.50 lM), indicative of AKT inhibition.
* Corresponding author.
Although selective over ROCK1, compound 1 was still a potent
E-mail address: hong.2.lin@gsk.com (H. Lin).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.11.060

680
H. Lin et al. / Bioorg. Med. Chem. Lett. 20 (2010) 679–683
that displayed greater than 80% inhibition of GSK3b phosphoryla-
tion in BT474 tumor xenografts.
O
H
A
Y
N
B
To improve the overall profile of compound 1, we took a sys-
tematic approach to introduce one or two nitrogen atoms in the
indazole ring to increase polarity of the molecule and to lower
the c log P values. In particular, we were interested in making 7-
azaindazole 2a, 4-azaindazole 2b, 4,7-diazaindazole 2c, 4,6-diaz-
aindazole 2d, and 6-azaindazole 2e8 as illustrated in Figure 1.
The synthesis of compound 2a is depicted in Scheme 1, and pro-
ceeded through boronate ester 8 as key step. Its preparation
started from the trisubstituted pyridine 3,3 which we also used
as the starting material for the preparation of compounds 2a–d.
Protection of the hydroxyl group of 3 with benzylbromide followed
by a Stille coupling with 1-ethoxyvinyltin afforded intermediate 4,
which was hydrolyzed under acidic conditions in one pot to give
acetylpyridine 5. Cyclization of 5 with anhydrous hydrazine affor-
ded 7-azaindazole 6, which was converted to triflate 7 after Boc
protection and debenzylation via hydrogenolysis. Triflate 7 was
then converted to boronate pinacolate 8 under Pd(0) catalyzed
conditions.9 Both dppf and Cy3P worked well as ligands for this
reaction.10 Bromopyridine 93 was subjected to consecutive Suzuki
coupling reactions with boronate ester 8 and 3-furanylboronate
acid, followed by Boc deprotection under standard conditions to af-
ford the final product 2a.11
The synthesis of compound 2b is depicted in Scheme 2 and re-
quired intermediate 14. The preparation of this compound com-
menced with the introduction of an acetyl group onto 3-
fluoropyridine, followed by cyclization with anhydrous hydrazine.
Deprotonation of 3-fluoropyridine with n-BuLi, followed by
quenching with N-methyl-N-(methyloxy)acetamide resulted in a
1:1 mixture of 11 and its 4-acetyl regio isomer. This mixture was
treated with anhydrous hydrazine at 120 °C and compound 11
was converted to the desired 4-azaindazole, which was protected
N
N
H
N
NH2
O
A = N, B = Y = CH, 2a;
A = B = CH, Y = N, 2b;
A = Y = N, B = CH, 2c;
A = CH, B = Y = N, 2d;
A = Y = CH, B = N, 2e
Figure 1. Azaindazole compounds.
inhibitor of many other kinases in the AGC superfamily, such as
p70S6K, PDK1, PKA and RSK. It was also observed to be a potent
inhibitor of PAK1, a kinase in the STE superfamily. Furthermore,
compound 1 was observed to be a very potent CYP3A4 inhibitor,
displaying <100 nM potency.
Based on its observed AKT potency, compound 1 was profiled in
an in vivo pharmacodynamic assay using a BT474 tumor xenograft
model in mice, measuring the inhibition of GSK3b phosphorylation
as the marker for intracellular AKT activity. However, compound 1
failed to show a pharmacodynamic effect in this experiment de-
spite having significant drug concentrations in tumor samples
(data not shown). We speculated that the absence of a pharmcody-
namic effect could be explained by the poor physical properties,
such as the high lipophilicity and high protein binding of com-
pound 1,6 thereby preventing it from reaching the target proteins
in vivo. We herein report our discovery of a series of azaindazole
analogs7 with improved drug-like properties and kinase selectivity
N
Cl
Cl
Cl
O
HN
Br
a,b
c
d
N
N
OEt
N
N
OH
OBn
OBn
OBn
3
4
5
6
Boc
Boc
N
N
N
N
N
e,f,g
h
i
N
Cl
Br
N
OTf
B
Boc
O
O
N
NH
7
O
8
9
O
H
H
N
N
N
N
Cl
O
N
N
j,k
N
N
Boc
H
N
H
N
NH
NH2
O
10
2a
Scheme 1. Synthesis of 7-azaindazole analog 2a. Reagents and conditions: (a) BnBr, K2CO3, acetone, reflux, quant.; (b) Pd2dba3, 2%, Ph3P, 8%, 1-ethoxyvinyltin, toluene, 110 °C,
2 h; in one pot (c) 3 N HCl, rt, overnight; (d) anhydrous NH2NH2, 120 °C, overnight, 67% over 3 steps; (e) Boc2O, Et3N, DMAP, DCM, 80%; (f) H2 balloon, Pd/C, EtOH, rt, 2 h, 99%;
(g) Tf2NPh, Et3N, DCM, rt, 2 h, 68%; (h) 4,4,40,40,5,5,50,50-octamethyl-2,20-bi-1,3,2-dioxaborolane, Pd(dppf)Cl2, KOAc, dioxane, 80 °C, overnight; (i) 9, Pd(Ph3P)4, 2 N Na2CO3,
microwave irradiation, 150 °C, 75% over 2 steps; (j) 3-furanylboronic acid, Pd(Ph3P)4, 2 N Na2CO3, microwave irradiation, 160 °C, 74%; (k) TFA, DCM, RP-HPLC purification,
53%.

H. Lin et al. / Bioorg. Med. Chem. Lett. 20 (2010) 679–683
Tr
681
Tr
H
N
F
F
N
N
e
d
a
b,c
N
N
N
N
O
N
Cl
N
N
N
O
11
12
14
13
O
H
N
Cl
Cl
O
O
N
Br
B
O
N
N
N
N
Boc
H
H
H
N
Boc
Boc
N
N
f
g,h,i
NH
NH
NH
O
O
9
15
2b
Scheme 2. Synthesis of 4-azaindazole analog 2b. Reagents and conditions: (a) BuLi, then N-methyl-N-(methyloxy)acetamide, THF, ꢀ78 °C, 84%, 1:1 mix. of 11 and
regioisomer; (b) anhydrous NH2NH2, 120 °C, overnight, 43%; (c) NaH, DMF, 0 °C, then TrCl, rt, 45%; (d) mCPBA, DCM, 0 °C to rt, 12 h, 98%; (e) POCl3, 120 °C, 1 h, 86%; (f)
5,5,50,50-tetramethyl-2,20-bi-1,3,2-dioxaborinane, Pd(dppf)Cl2ꢁCH2Cl2, KOAc, dioxane, 80 °C, overnight; (g) 14, Pd(Ph3P)4, 2 N Na2CO3 aq, microwave irradiation, 150 °C, 40%;
(h) 3-furanylboronate acid, Pd(Ph3P)4, 2 N Na2CO3, microwave irradiation, 160 °C, 97%; (i) TFA, DCM, RP-HPLC purification, 43%.
with a trityl group to give intermediate 12. The 5-Cl group was
introduced by oxidation of the nitrogen atom on the pyridine ring
with mCPBA, and chlorination of N-oxide 13 with POCl3 to give 5-
Cl-4-azaindazole 14.12,13 Compound 9 was converted into boronate
ester 15 with 5,5,5’,5’-tetramethyl-2,20-bi-1,3,2-dioxaborinane un-
der Pd(0) catalyzed conditions.14,15 Two successive microwave-as-
sisted Suzuki coupling reactions followed by Boc deprotection gave
compound 2b.
The preparation of 4,7-diazaindazole 2c is shown in Scheme 3.
The synthesis required compound 19, which in turn was prepared
from chloropyrazine 17. The acetyl group of 17 was introduced
either by a Stille reaction of 2,3-dichloropyrazine and 1-ethoxyvi-
nyltin followed by the hydrolysis under acidic conditions, or, by
a tele-substitution of 2,6-dichloropyrazine with dithiane anion fol-
lowed by AgNO3 assisted oxidative cleavage of dithiane 18.16 The
advantage of the latter method is that it avoids the use of highly
toxic organo stannane reagents. Cyclization of compound 17 to
4,7-diazaindazole 19 was accomplished by heating compound 17
with 1 equiv of hydrazine in pyridine (0.05 M concentration to
avoid intermolecular side reactions). The 5-bromo group was in-
stalled following the same sequence that was used to introduce
5-Cl group on 4-azaindazole core of compound 14 except that
POBr3 was used instead of POCl3. Compound 20 was then protected
with Boc2O to give 21, which was subjected to consecutive micro-
wave-mediated Suzuki coupling reactions with deprotection and
reverse phase HPLC purification to afford the final 4,7-diazaindaz-
ole derivative 2c.
Table 2 summarizes some biological and developability proper-
ties of the novel azaindazole analogs (2a–e) in comparison to inda-
zole containing compound 1. Except for 4-azaindazole 2b, the
other azaindazole analogs 2c–e were equally potent against
AKT1, but less potent against AKT2/3. In both cellular proliferation
and mechanistic assays, compound 2c appeared to be most potent
and selective in tumor cells (LnCAP, BT474) containing constitu-
tively activated AKT versus normal cells (HFF) lacking activated
AKT.
Since azaindazole derivatives 2a, 2c and 2d displayed lower
clogP values than that of indazole 1 in a range of 3.3–3.8, it was
not surprising to see these compounds displayed improved
drug-like properties. In general, they displayed reduced CYP450
Cl
Cl
Cl
a
N
N
OEt
N
N
N
HN
b
e
O
Cl
16
f
N
N
N
Cl
S
N
c, d
N
S
19
17
S
S
N
18
O
H
N
N
N
N
R
N
N
N
g,h,i
N
k,l,m
H
N
N
NH2
Br
O
R=H, 20
R=Boc,21
j
2c
Scheme 3. Synthesis of 4,7-diazaindazole analog 2c. Reagents and conditions: (a) Pd2dba3, 2 mol %, Ph3P, 8 mol %, 1-ethoxyvinyltin, toluene, 110 °C, 2 h; (b) 2 N HCl,
acetonitrile, rt, overnight, 72% over 2 steps; (c) BuLi, ꢀ20 °C, MeI, ꢀ50 °C to rt, THF; (d) in one pot, BuLi, ꢀ20 °C, 2,6-dichloropyrazine, ꢀ50 °C to rt, 98%; (e) NCS, AgNO3,
acetonitrile/H2O 4:1; (f) NH2NH2 hydrate, pyridine, 0.05 M, 120 °C, overnight, 62% over two steps; (g) NaH, DMF, 0 °C, then TrCl, rt, 62%; (h) mCPBA, DCM, 0 °C to rt, 12 h, 92%;
(i) POBr3, 90 °C, 2.5 h, 52%; (j) Boc2O, Et3N, DMAP, DCM, 68%; (k) 15, Pd(Ph3P)4, 2 N Na2CO3 aq, microwave irradiation, 150 °C, 88%; (l) 3-furanylboronate acid, Pd(Ph3P)4, 2 N
Na2CO3, microwave irradiation, 160 °C, 92%; (m) TFA, DCM, RP-HPLC purification, 53%.

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H. Lin et al. / Bioorg. Med. Chem. Lett. 20 (2010) 679–683
Table 2
pGSK3B (% Inhibition)
Blood Conc (ng/ml)
Tumor Conc (ng/g)
Some biological and developability data of azaindazole analogs
Compound
1
2a
2b
2c
2d19
2e20
a
120
100
80
60
40
20
0
10000
1000
100
10
AKT1 IC50
AKT2 IC50
AKT3 IC50
LnCAP IC50
BT474 IC50
HFF IC50
pGSK3b IC50
CYP450 3A4 IC50
HT solubility
(
(
(
l
l
l
M)
M)
M)
M)
M)
0.001
0.012
0.001
0.19
0.34
5.5
0.50
0.050
52
0.001
ND
0.012
ND
0.002
0.039
0.010
0.096c
0.37c
14.3c
0.16
0.40
200
90.9
3.31
0.001
0.031
0.015
0.54c
0.64c
30c
0.67
1.3
205
0.001
0.006
0.001
0.23
0.75
6.5
0.064
0.016
NT
a
a
ND
ND
0.085c
0.30c
6.6c
0.83c
2.1c
30c
b
(
l
b
(l
b
(lM)
c
(lM)
0.26
0.20
108
95.3
3.75
3.86
0.10d
225
93.1
4.17
(lM)
lM
Protein binding%
c log p
95.9
4.45
84.5
3.31
94.3
3.96
a
b
c
n P 2.
Inhibition of cell proliferation.
Inhibition of phosphorylation of GSK3b. Data were collected in methylene blue
1
0
12.5
50
(MEB) format.22
d
DEF = diethoxyfluorescein was used as CYP3A4 probe substrate.
Compound 2c (mg/kg)
Figure 3. Dose response PD effect of 2c on GSK3b phosphorylation in BT474 tumors
in female SCID mice.
inhibition compared to indazole 1, especially versus the 3A4
isozyme.17,18 The azaindazole analogs also had increased solubility,
which was particularly important for the development of an
intravenous (iv) administrated agent, due to the lack of oral
exposure in this chemotype. Furthermore, the azaindazole analogs
displayed reduced protein binding (e.g., compound 2c vs 1), a
factor that we suspected to be responsible for compound 1 not
showing a pharmacodynamic effect in the mouse xenograft tumor
model.
Compound 2c not only had an improved overall profile in terms
of cellular potency and drug-like properties, but also displayed im-
proved kinase selectivity compared to indazole 1 (Fig. 2).
While maintaining AKT potency, compound 2c displayed great-
er than 10-fold decreased potency against PKA, and almost 100-
fold decreased potency against MSK1. These two kinases are close
relatives of AKT in the AGC superfamily. Although it is not com-
pletely clear to us why 4,7-diazaindazole 2c would be more selec-
tive than indazole 1, we suspect that 4,7-diazaindazole might be a
weaker H-bond acceptor due to the electronic effect of the N atoms
in the six-member ring.23 Therefore, the AKT potency of 2c might
be driven more by the specific interactions with other parts of
the protein, and less by the H-bond interactions with the hinge,
which are common for all kinases. As a consequence, an ATP com-
petitive inhibitor, such as compound 2c with a ‘weaker’ hinge bin-
der, may be slightly less potent against AKT than indazole 1, while
being more selective over other kinases.
Since compound 2c had the best overall profile in terms of
potency, selectivity and drug-like properties among other
azaindazole analogs, it was characterized in a BT474 xenograft
pharmacodynamic study. As shown in Figure 3, compound 2c dem-
onstrated greater than 80% inhibition of GSK3b phosphorylation at
a dose of 50 mg/kg (intraperitoneal administration). This pharma-
codynamic effect mirrows well with the pharmacokinetic results.24
The level of inhibition (89%) of GSK3b phosphorylation is consis-
tent with cellular potency (160 nM IC50) and drug concentration
(3798 ng/mL) in tumor after correction protein binding for the free
drug fraction.
In summary, we have described the synthesis and biological
activities of novel azaindazole analogs as potent AKT inhibitors.
Compound 2c showed improved drug-like properties and kinase
selectivity with respect to indazole 1, and demonstrated an
in vivo pharmacodynamic effect in BT474 tumor xenografts.
100000
Compound 1 Compound 2c
10000
1000
100
10
1
Figure 2. Comparison of the kinase selectivity between compound 1 and 4,7-diazaindazole analog 2c.

H. Lin et al. / Bioorg. Med. Chem. Lett. 20 (2010) 679–683
683
Takata, D.; Luengo, J. I.; Kahana, J. A.; Zhang, S.; Robell, K. A.; Levy, D.; Kumar,
R.; Choudhry, A. E.; Schaber, M.; Lai, Z.; Brown, B. S.; Donovan, B. T.; Minthorn,
E. A.; Brwon, K. K.; Heerding, D. A. Bioorg. Med. Chem. Lett., doi:10.1016/
j.bmcl.2009.11.064.
Acknowledgment
The authors thank Dr. Arthur Shu for preparing 7-azaindazole 6
and 4,7-diazaindazole 20 in large scale to support the SAR study.
18. Replacement of indazole with thienopyrazole did not reduce CYP450 3A4
inhibition (data not shown). For preparation of thienopyrazole derivatives, see:
Yamashita, D. S.; Lin, H.; Wang, W. PCT Int. Appl. WO2005085227, 203, 2005.
19. The 4,6-diazaindazole analog 2d was prepared similarly to the above
mentioned azaindazole analogs. A regio selective Stille coupling reaction of
2,4-dichloro-5-fluoropyrimidine and 1-ethoxyvinyltin followed by acidic
hydrolysis of the vinyl ether and subsequent cyclization with 1 equiv of
hydrazine hydrate afforded 5-chloro-4,6-diazaindazole 22. Two consecutive
microwave-assisted Suzuki coupling reactions of 22 with boronate ester 15
and 3-furanylboronate acid followed by acidic deprotection and reverse phase
HPLC purification furnished final target molecule 2d. Although this synthetic
route was suitable for preparing analogs in small scale, it was not optimized for
gram-scale synthesis due to low yields during formation of 22 and subsequent
References and notes
1. (a) Karaman, M. W.; Herrgard, S.; Treiber, D. K.; Gallant, P.; Atteridge, C. E.;
Campbell, B. T.; Chan, K. W.; Ciceri, P.; Davis, M. I.; Edeen, P. T.; Faraoni, R.;
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Heerding, D. A.; Duckett, D. R.; Eberwein, D. J.; Knick, V. B.; Lansing, T. J.;
McConnell, R. T.; Gilmer, T. M.; Zhang, S. Y.; Robell, K.; Kahana, J. A.; Geske, R.
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Suzuki coupling reactions.
O
N
N
N
F
N
N
N
N
N
N
Cl
N
Cl
Cl
N
N
NH2
O
22
2d
SO2Ph
N
N
5. A compound that is less potent against HFF in proliferation assay is considered
to be less cytotoxic and to have a cleaner selectivity profile in general.
6. The cellular potency of compound 1 in BT474 proliferation assay shifted sixfold
to be less potent when protein was added.
N
Br
7. For easy comparison with the indazole, the pyrazolopyridine, pyrazolopyrazine
or pyrazolopyrimidine analogs are all called azaindazoles instead. For example,
4-azaindazole is 1H-pyrazolo[4,3-b]pyridine, 4,7-diazaindazole is 1H-
23
20. The 6-azaindazole analog 2e was prepared in a similar manner to the synthesis
of 2b except for the use of 5-bromo-6-azaindazole 23 as a coupling partner
with boronate ester 15.21 Basic conditions are required to deprotect the
benzenesulfonamide on the 6-azaindazole ring.
21. Verma, S. K.; LaFrance, L. V. Tetrahedron Lett. 2009, 50, 383.
22. Rusnak, D. W.; Lackey, K.; Affleck, K.; Wood, E. R.; Alligood, K. J.; Rhodes, N.;
Ketih, B. R.; Murray, D. M.; Knight, W. B.; Mullin, R. J.; Gilmer, T. M. Mol. Cancer
Ther. 2001, 1, 85.
pyrazolo[3,4-b]pyrazine
d]pyrimidine.
and
4,6-diazaindazole
is
1H-pyrazolo[4,3-
8. The 6-azaindazole was described in Abbott’s publication on 2,3-disubstituted
pyridine AKT inhibitors: Zhu, G.-D.; Gandhi, V. B.; Gong, J.; Thomas, S.; Woods,
K. W.; Song, X.; Li, T.; Diebold, R. B.; Luo, Y.; Liu, X.; Guan, R.; Klinghofer, V.;
Johnson, E. F.; Bouska, J.; Olson, A.; Marsh, K. C.; Stoll, V. S.; Mamo, M.;
Polakowski, J.; Campbell, T. J.; Martin, R. L.; Gintant, G. A.; Penning, T. D.; Li, Q.;
Rosenberg, S. H.; Giranda, V. L. J. Med. Chem. 2007, 50, 2990.
23. Electrostatic potential of the two hinge binders indicate that 4,7-diazaindazole
have weaker H-bond interaction to hinge (calculated using Density Function
9. Boronate ester 8 is very stable. It can be purified on silica gel column and stored
as a white solid.
**
Theory with B3LYP/6-31G basis set within JAQUAR, Version 7.5; Schrodinger,
10. Ishiyama, T.; Ishida, K.; Miyaura, N. Tetrahedron 2001, 57, 9813.
11. These two Suzuki reactions worked well under thermal conditions, but for
efficiency, microwave conditions were used often on mg to g scales.
12. Ohi, N.; Sato, N.; Soejima, M.; Doko, T.; Terauchi, T.; Naoe, Y.; Motoki, T. PCT Int.
Appl. WO2003101968, 2003.
LLC: New York, NY, 2008).
13. Transformation of 14 to its stannane reagent or boronate ester for coupling
with bromopyridine 9, was not successful.
14. 4,4,40,40,5,5,50,50-Octamethyl-2,2’-bi-1,3,2-dioxaborolane did not give the
corresponding boronate pinacolate under the same condition.
15. Boronate ester 15 can either be used as a crude reaction mixture or purified on
silica gel for storage.
16. Torr, J. E.; Large, J. M.; Horton, P. N.; Hursthouse, M. B.; McDonald, E.
Tetrahedron Lett. 2006, 47, 31.
17. Furan, indole and pyridine are all canonical CYP450 culprits. Modification of
indole and replacement of furan (compounds in Ref. 3, CYP450 data not shown)
did not result in improvement of CYP450 profile. Modification of pyridine is
addressed in a separate publication: Lin, H.; Yamashita, D. S.; Xie, R.; Zeng, J.;
Wang, W.; Leber, J.; Safonov, I. G.; Verma, S.; Li, M.; LaFrance, L; Venslavsky, J.;
24. Although the pharmacodynamic effect appeared to be inverted at the 12.5 and
25 mg/kg doses, the similar tumor concentrations at these two doses and the
error bars indicated a lack of significant difference in pharmacodynamic effect
between these two dose levels.