Pyrazolopyridine inhibitors of B-RafV600E. Part 3: An increase in aqueous solubility via the disruption of crystal packing

Article abstract of DOI:10.1016/j.bmcl.2011.12.030

A single crystal was obtained of a lead B-Raf^V600E inhibitor with low aqueous solubility. The X-ray crystal structure revealed hydrogen-bonded head-to-tail dimers formed by the pyrazolopyridine and sulfonamide groups of a pair of molecules. Thi

Full text of DOI:10.1016/j.bmcl.2011.12.030

Bioorganic & Medicinal Chemistry Letters 22 (2012) 912–915
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Pyrazolopyridine inhibitors of B-RafV600E. Part 3: An increase in aqueous
solubility via the disruption of crystal packing
Steve Wenglowsky a, David Moreno a, , Joachim Rudolph b, Yingqing Ran b, Kateri A. Ahrendt a,
⇑
Alisha Arrigo a, Ben Colson a, Susan L. Gloor a, Gregg Hastings a
a Array BioPharma, 3200 Walnut Street, Boulder, CO 80301, United States
b Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080-4990, United States
a r t i c l e i n f o
a b s t r a c t
A single crystal was obtained of a lead B-RafV600E inhibitor with low aqueous solubility. The X-ray crystal
structure revealed hydrogen-bonded head-to-tail dimers formed by the pyrazolopyridine and sulfon-
amide groups of a pair of molecules. This observation suggested a medicinal chemistry strategy to disrupt
crystal packing and reduce the high crystal lattice energy of alternative inhibitors. Both a bulkier group at
the interface of the dimer and an out-of-plane substituent were required to decrease the compound’s
melting point and increase aqueous solubility. These substituents were selected based on previously
developed structure–activity relationships so as to concurrently maintain good enzymatic and cellular
Article history:
Received 8 November 2011
Revised 1 December 2011
Accepted 5 December 2011
Available online 10 December 2011
Keywords:
B-RafV600E
activity against B-RafV600E
.
Aqueous solubility
Single-crystal X-ray
Crystal packing
Crystal lattice energy
Ó 2011 Elsevier Ltd. All rights reserved.
Our laboratory has recently disclosed a series of ATP-competitive
B-RafV600E inhibitors which utilized 3-methoxy pyrazolopyridine as
a novel hinge-binding group.1,2 Optimization led to compounds 1
and 2, potent and selective inhibitors of B-RafV600E, which were
highly active against a broad panel of melanoma and colon cancer
cell lines driven by this activating mutation (Fig. 1). Although com-
pounds 1 and 2 possessed favorable ADME profiles, their aqueous
led to oral exposures for these compounds sufficient for significant
in vivo anti-tumor efficacy.
While SDD formulations offer an approach to improve oral
exposure and have been used successfully in the clinic,4 an addi-
tional processing step is required for manufacturing. Another issue
is the presence of a large amount of polymer which presents a
higher pill burden for the patient. Thus, the development of a po-
tent and efficacious B-RafV600E inhibitor with an increase in aque-
ous solubility would be advantageous.
solubility was low (<10 lg/mL at pH 6.5 and 7.4). As a result, oral
exposure in mice was best achieved utilizing a solution formulation
of 40% PEG400/10% ethanol/50% water. Due to concerns with daily
dosing of high concentrations of PEG400 in efficacy and tolerability
studies, compounds 1 and 2 were reformulated as amorphous spray-
dried dispersions (SDD) on hydroxypropyl methylcellulose acetate
succinate (HPMCAS) polymer at 25% loading.3 The SDD formulation
In general, the aqueous solubility of a solute is dependent upon
two factors: the ability of the solute to interact with water (lipophil-
icity) and the crystal lattice energy of the solute.5 While most of the
analogs prepared during the lead optimization of the pyrazolopyri-
dine series fell within a narrow range of lipophilicity (ClogP = 1.43–
1.86), a broad range of melting points was observed (MP = 173–
261 °C). As predicted by the general solubility equation of Jain and
Yalkowsky, in which logS = 0.5 À 0.01(MP À 25) À ClogP,5 a wide
range of aqueous solubility was likewise observed and correlated
with melting point. This broad range of melting points within a ser-
ies of structurally similar analogs suggests that subtle crystal pack-
ing effects exist which are modulated by varying the substituents
around the molecule. In an effort to exploit this effect and rationally
guide the discovery of a potent B-RafV600E inhibitor with reduced
crystal lattice energy, a single crystal of compound 1 was obtained.
Reported herein is the design and synthesis of alternative B-RafV600E
inhibitors which bear substituents that disrupt the observed crystal
packing of 1 and lead to compounds with lower melting points and
increased aqueous solubility.6,7
F
Cl
O
O
S
O O
H
N
H
N
S
N
N
N
N
H
H
F
F
O
O
HN
HN
N
N
OMe
1
OMe
2
Figure 1. B-RafV600E inhibitors 1 and 2.
⇑
Corresponding author.
E-mail address: david.moreno@arraybiopharma.com (D. Moreno).
0960-894X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2011.12.030

S. Wenglowsky et al. / Bioorg. Med. Chem. Lett. 22 (2012) 912–915
913
Figure 2. X-ray crystal structure of 1. Water molecules are represented as blue
spheres. Carbon atoms are rendered in green, hydrogen in white, nitrogen in blue,
oxygen in red, fluorine in light blue and sulfur in yellow. Hydrogen bonds
interactions are illustrated with yellow dashed lines and hydrogen bond distances
are given in Angstroms. Numbering around the central phenyl ring is indicated.
Figure 3. X-ray crystal structure of 1. Carbon atoms are rendered in gray, hydrogen
in white, nitrogen in blue, oxygen in red, and sulfur in yellow. Hydrogen bonds
interactions are depicted by cyan dash lines and the unit cell is illustrated. The 3-
methoxy substituents of a dimer of 1 are highlighted with white arrows.
Sixteen slow evaporation and sixteen slow diffusion experi-
ments were carried out on 1 in order to prepare suitable material
for structure determination by X-ray diffraction.8 A mixed solvent
system of 70:30 EtOH–H2O provided colorless plates of sufficient
size and quality for structure determination.9 The crystal structure
revealed that the monohydrate of compound 1 crystallizes in an
extended conformation, an arrangement which leads to the forma-
tion of head-to-tail dimers. The donor and acceptor pair of the pyr-
azolopyridine forms two hydrogen bonds with a donor and
acceptor pair of the sulfonamide from another molecule of 1; this
then positions the pyrazolopyridine from the second molecule of
1 to form hydrogen bonds back to the sulfonamide of the first mol-
ecule (Fig. 2). The four aromatic rings of the dimer lie in the same
plane, while the amide linkers are rotated out of this plane and do
not take part in the dimer formation. The presence of four hydro-
gen bonds between the two molecules of the dimer represents a
stable arrangement in the crystalline state, and is likely a common
feature of many of the analogs within this series.
activity relationships developed for this series,2 it was proposed
that the incorporation of a chlorine in place of the fluorine at the
2-position of the central phenyl ring would maintain activity
against the target while weakening two of the hydrogen bonds of
the dimer (Fig. 2). The required 2-Cl, 6-F substitution on this cen-
tral phenyl ring led to compound 3.
The second hypothesis that could disrupt the crystal packing of
an analog of 1 was to introduce an out-of-plane substituent.6,10,11
The propensity of the pyrazolopyridine to engage in p-stacking sug-
gested attaching the out-of-plane substituent directly to the hetero-
cycle, and the replacement of the 3-methoxy substituent was
proposed (Fig. 3). Previously determined structure–activity rela-
tionships revealed that although 3-alkoxy groups on the pyrazolo-
pyridine hinge-binding core provided compounds with the best
cellular activity (pERK 6 20 nM), several other 3-substituents pro-
vided inhibitors with only a 2- to 4-fold reduction in potency (-Br,
-I, -Me, -Et: pERK = 36–86 nM).2 Thus, it was proposed that a small,
branched group at the 3-position could impart both the desired B-
RafV600E cellular activity and a lower melting point than 1. This
hypothesis led to 3-isopropyl and 3-cyclopropyl pyrazolopyridines
4 and 5.
As expected, compound 3 was essentially equipotent with 1 and
2 in the enzymatic and cellular assays against B-RafV600E (Table 1).12
However, the melting point of 3 was nearly identical to 1 (221 vs
229 °C) suggesting that the substitution of chlorine for fluorine at
the 2-position of the central phenyl ring was insufficient to disrupt
head-to-tail dimer formation. Given that the ClogP of 3 was also
similar to both 1 and 2, no improvement in aqueous solubility
was expected which was verified experimentally.13
Additional analysis of the X-ray crystal structure of 1 revealed
that each pyrazolopyridine forms a
p-stacking interaction with
another pyrazolopyridine both above and below the plane of each
dimer. Likewise, the central phenyl rings are in proximity to form
p-stacking interactions. In this way, the dimer pairs stack one on
top of another (Fig. 3). Due to the rotation of the amides out of
the plane of the dimers (Fig. 2), they are aligned to form hydrogen
bonds both above and below with the amides from another dimer
pair. Thus the
tween the amide linkers reinforce each other and result in the for-
mation of a long-range network of -stacked dimers. This network
p-stacking and hydrogen bonding interactions be-
p
appears to be a highly stable arrangement and likely contributes to
the high melting point of compound 1 and many of the analogs in
this series of B-RafV600E inhibitors.
Compounds
4 and 5 were prepared next via established
These observations led to two hypotheses that could disrupt the
crystal packing of an analog of 1 and lead to a compound with a
lower melting point and increased aqueous solubility. The first
was to destabilize the head-to-tail dimer formation. Since the
hydrogen bond donors on the pyrazolopyridine and sulfonamide
synthetic methods.1 3-Isopropyl substituted pyrazolopyridine 4
(B-RafV600E = 14 nM, pERK = 89 nM, Table 1) was equipotent to pre-
viously prepared 3-methyl (B-RafV600E = 12 nM, pERK = 86 nM) and
3-ethyl (B-RafV600E = 9.2 nM, pERK = 84 nM) pyrazolopyridines.2
However, these compounds were all >4-fold less active in the cel-
lular assay versus comparator compound 1. In addition, despite the
introduction of the out-of-plane substituent, 3-isopropyl pyrazolo-
pyridine 4 still possessed low aqueous solubility. The 3-cyclopro-
pyl pyrazolopyridine 5, in contrast to all other alkyl substituents
examined, was equipotent to 1. However, like compound 4, 3-
are critical for binding to B-RafV600E 1
, it would not be possible to
destabilize the dimer by blocking either of these groups (by, e.g.,
methylation) and still maintain potency. An alternative method
would be to incorporate a sterically bulky group at the dimer
interface proximate to one of the hydrogen bonds. Based on the
X-ray crystal structure of 1 bound to B-RafWT and the structure–

914
S. Wenglowsky et al. / Bioorg. Med. Chem. Lett. 22 (2012) 912–915
Table 1
B-RafV60E activity, solubility and melting point of compounds 1–8
F
F
F
O
O
O
O
O O
H
N
H
N
H
N
S
S
S
F
N
N
N
N
N
N
H
H
H
O
X
O
Cl
O
Cl
HN
N
HN
HN
N
N
3 : R = OMe, X = Cl
8
7
R
4 : R = iPr,
5 : R =
X = F
X = F
X = Cl
6 : R =
a
a
Compound
B-Raf IC50 (nm)
pERK IC50 (nm)
Sol. pH 6.5, 7.4b
MPc (°C)
MW
ClogP
1
2
3
4
5
6
7
8
4.8
1.7
2.2
14
2.7
3.8
2.0
0.6
19
20
19
89
23
33
18
51
4, 9
<1, 2
229
261
221
n.d.d
217
164
213
154
425
442
442
438
436
452
466
470
1.61
1.76
1.64
2.63
2.15
2.19
2.59
1.61
<1, 2
6, n.d.d
1, 4
54, 127
1, <1
130, 265
a
b
c
Values are means of at least two experiments.
g/mL.
MP = melting point of recrystallized material which provided the highest melting polymorph.
l
d
n.d. = not determined.
cyclopropyl pyrazolopyridine 5 showed no significant reduction in
melting point versus 1 (217 °C) and similarly poor aqueous
solubility.
compared to 1 rendering dimer formation impossible (Fig. 5). As
such, the hydrogen bonds of compound 6 must be satisfied via
an alternative arrangement in the solid state, leading to reduced
crystal lattice energy, decreased melting point and higher aqueous
solubility. The substitution of 3-cyclopropyl for 3-methoxy on the
pyrazolopyridine must be required to achieve this alternative con-
formation since the melting point and low aqueous solubility of 3
suggests a similar crystal lattice formation to 1. Since compound 6
possesses higher molecular weight than compounds 1–5, and
greater lipophilicity than compounds 1–3, crystal packing must
play the predominant role in determining its aqueous solubility.
It was of interest to know whether the increase in aqueous sol-
ubility observed for 6 would translate to related compounds bear-
ing sulfonamide tails other than propyl. Previously determined
structure–activity relationships revealed two propyl replacements
with similar activity, isobutyl and 3-fluoropropyl.2 Incorporation of
these groups at the sulfonamide of 6 led to compounds 7 and 8.
The cellular activity of isobutyl sulfonamide 7 was excellent
(pERK = 18 nM), yet the inclusion of this single methyl group on
the molecule led to a significant increase in melting point and a
complete erosion of the increased aqueous solubility seen with 6.
This result was unexpected since additional branching was ex-
pected to maintain or even further increase aqueous solubility,
yet the melting point indicates this compound is still able to adopt
some highly stable arrangement in the crystalline state. In contrast,
the melting point and aqueous solubility of compound 8 suggests
the formation of a similar crystalline polymorph to that of 6. The
addition of the 3-fluoro group to the propyl sulfonamide tail of 6
Although neither the incorporation of a bulky substituent at the
dimer interface nor an out-of-plane substituent at the pyrazolo-
pyridine 3-position was sufficient to induce an increase in aqueous
solubility, it seemed prudent to apply both of these hypotheses to
the same molecule. This strategy led to B-RafV600E inhibitor 6.
The cellular activity of compound 6 (pERK = 33 nM) was within
twofold of compounds 1–3 and 5. Furthermore, the melting point
of 6 (164 °C) was >50 °C lower than these inhibitors indicating that
the crystal lattice energy of 1 was significantly reduced. Despite
the increase in lipophilicity resulting from the replacement of the
methoxy group with a cyclopropyl group, the aqueous solubility
of 6 nonetheless increased >10-fold versus 1, and was >50-fold
greater than 2 and 3 (Table 1). A recrystallization screen with over
10 solvent systems failed to produce a crystal with a higher melt-
ing point. Differential scanning calorimetry (DSC) confirmed the
melting point of 164 °C and indicated a second polymorph melting
at 140 °C.
A single crystal of 6 was obtained to account for its low melting
point.14 The X-ray structure revealed no head-to-tail dimer forma-
tion which led to fewer p-stacking interactions than for 1 (Fig. 4).
The inability of 6 to form head-to-tail dimers results from the con-
formation of the central phenyl ring. While compound 6 also re-
sides in an extended conformation, the bond from the amide
carbonyl to the central phenyl ring is rotated approximately 180°
F
O
O
H
N
O
O
S
S
HN
N
H
N
Cl
O
Cl
N
H
H
N
N
N
H
N
O
F
N
N
H
N
Cl
O
F
H
N
N
O
O
6
N
H
S
Figure 4. X-ray crystal structure of 6. Carbon atoms are rendered in green,
hydrogen in white, nitrogen in blue, oxygen in red, fluorine in light blue and sulfur
in yellow. Hydrogen bond interactions are illustrated with yellow dashed lines and
hydrogen bond distances are given in Angstroms.
Figure 5. Conformation change of
demanding substituents.
6 due to the incorporation of sterically

S. Wenglowsky et al. / Bioorg. Med. Chem. Lett. 22 (2012) 912–915
915
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Wen, Z. Biorg. Med. Chem. Lett. 2011, 5533.
3. Friesen, D. T.; Shanker, R.; Crew, M.; Smithey, D. T.; Curatolo, W. J.; Nightingale,
J. A. S. Mol. Pharm. 2008, 5, 1003.
4. Bollag, G.; Hirth, P.; Tsai, J.; Zhang, J.; Ibrahim, P. N.; Cho, H.; Spevak, W.; Zhang,
C.; Zhang, Y.; Habets, G.; Burton, E. A.; Wong, B.; Tsang, G.; West, B. L.; Powell,
B.; Shellooe, R.; Marimuthu, A.; Nguyen, H.; Zhang, K. Y. J.; Artis, D. R.;
Schlessinger, J.; Su, F.; Higgins, B.; Iyer, R.; D’Andrea, K.; Koehler, A.; Stumm, M.;
Lin, P. S.; Lee, R. J.; Grippo, J.; Puzanov, I.; Kim, K. B.; Ribas, A.; McArthur, G. A.;
Sosman, J. A.; Chapman, P. B.; Flaherty, K. T.; Xu, X.; Nathanson, K. L.; Nolop, K.
Nature 2010, 467, 596.
F
F
F
O
O
S
O O
a, b
c
RO
S
NH2
N
S
O
R
N
H
Cl
O
Cl
Cl
O
9
10: R = Bn
11: R = Me
12: R = CO2H
13: R = H
Scheme 1. Reagents and conditions: (a) 1.05 equiv, n-BuLi, THF, À78 °C, 1,2-
bis(chlorodimethylsilyl)ethane, 1 h, then 1.05 equiv, n-BuLi, À78 °C to 22 °C, 1 h,
then 1.05 equiv, n-BuLi, R-chloroformate, À78 °C, 1 h, 85% for R = Bn, 88% for
R = Me; (b) propane-1-sulfonyl chloride, TEA, DCM, 22 °C, 1 h, 82% for 10, 86% for
11; (c) aq hydroxide, 4:1 THF/MeOH.
5. Jain, N.; Yalkowsky, S. H. J. Pharm. Sci. 2001, 90, 234.
6. Examples of increasing aqueous solubility by the disruption of molecular
planarity: (a) Fray, M. J. J. Med. Chem. 2001, 44, 1951; (b) Lanier, M. C.;
Moorjani, M.; Luo, Z.; Chen, Y.; Lin, E.; Tellew, J. E.; Zhang, X.; Williams, J. P.;
Gross, R. S.; Lechner, S. M.; Markison, S.; Joswig, T.; Kargo, W.; Piercey, J.;
Santon, M.; Malany, S.; Zhao, M.; Petroski, R.; Crespo, M. I.; Diaz, J. –L.;
Saunders, J.; Wen, J.; O’Brien, Z.; Jalali, K.; Madan, A.; Slee, D. H. J. Med. Chem.
2009, 52, 709; (c) Fujita, Y.; Yonehara, M.; Tetsuhashi, M.; Noguchi-Yachide, T.;
Hashimoto, Y.; Ishikawa, M. Bioorg. Med. Chem. Lett. 2010, 18, 1194.
7. Our laboratory has pursued an additional successful method to disrupt the
observed crystal packing of this series which provided an alternative series of
B-RafV600E inhibitors with lowered melting point and improved aqueous
solubility: Ren, L.; Laird, E. R.; Buckmelter, A. J.; Dinkel, V.; Gloor, S. L.; Grina,
J.; Newhouse, B.; Rasor, K.; Hastings, G.; Gradl, S. N.; Rudolph, J. Bioorg. Med.
Chem. Lett. doi: 10.1016/j.bmcl.2011.11.092.
8. Slow evaporation procedure: 15–20 mg of compound 1 were added to 16
separate 8 mL vials and to each was added the solvent or mixture of solvents at
room temperature until dissolution was observed. Vials were heated to 50–
75 °C as required for dissolution. The vials were closed and a small hole was
pierced in the cap, and the vials were left at room temperature until
crystallization occurred. Vapor diffusion procedure: 15–20 mg of compound
1 were added to 16 separate 16 mL vials; to 8 of the vials was added 8.2 mL of
EtOH, while to the other 8 vials 8.2 mL of MeOH was added. Each vial was
placed into a 20 mL vial containing a polar or highly non-polar antisolvent. The
20 mL vials were closed and left at room temperature until crystallization
occurred.
reduces the melting point further to 154 °C and increases the aque-
ous solubility over 6 by twofold. While the cellular activity of com-
pound 8 was attenuated, it was still within threefold of compound
1. Compared to compound 2, the melting point of compounds 6
and 8 were 100 °C less and resulted from only minor structural
changes.
The synthesis of the requisite 2-chloro-6-fluoro-3-(propylsulfo-
namido)benzoic acid 12 initially followed the route used to prepare
the regioisomeric 6-chloro-2-fluoro-3-(propylsulfonamido)benzoic
acid (Scheme 1).1 In one step, 2-chloro-4-fluoro aniline 9 was pro-
tected with 1,2-bis(chlorodimethylsilyl)ethane, metalated and
acylated with benzyl chloroformate. Under aqueous workup condi-
tions the bis-silyl amine was deprotected, and the resulting aniline
was bis-sulfonylated to give 10. However, although the regioisomer
of 10, where the chloro and fluoro substituents were reversed,
underwent ester hydrolysis with aqueous KOH at 80 °C, the benzyl
ester 10 provided no trace of acid 12 under these conditions. More
forcing hydrolysis conditions, with aqueous Ba(OH)2 at 80 °C, pro-
vided the desired acid 12; unfortunately, these conditions led to
concomitant decarboxylation leading to 13. Ultimately, a facile
hydrolysis that provided 12 cleanly was obtained via the methyl es-
ter 11. Hydrolysis with KOH at 80 °C for 16 h provided compound
12 in 58% yield with no trace of decarboxylation. Acid 12 was then
coupled to the appropriate anilines under the standard conditions
to provide the desired inhibitors.1
9. Crystal structure determination of 1 was made by Avantium Technologies BV.
The single crystal measurements were performed on a Nonius Kappa-CCD
diffractometer equipped with an Oxford Cryostream Liquid Nitrogen Cooler
using Mo K radiation. The data were collected at 293 and 120 K. The full sphere
a
data were collected up to h = 32.5° (17219 reflections) at 120 K and up to
h = 27.5° (1919 reflections) at 293 K. Data reduction was performed using HKL
Scalepack from 8712 reflections within h range 2–32°. The structure was solved
using direct methods by SHELX-97. The structure was refined by least square full
matrix refinement using SHELX-97. All H-atoms were found on the Fourier
difference map and refined isotropically. The absolute configuration was
determined using Flack parameters based on anomalous dispersion effect.
Crystal data and structure refinement for 1: C17H17F2N5O4SÁH2O, monoclinic,
In summary, potent B-RafV600E inhibitors with improved aque-
ous solubility were prepared. A single crystal X-ray of lead com-
pound 1 was obtained, and a medicinal chemistry strategy was
developed to disrupt its observed crystal packing. The combination
of both an out-of-plane substituent and a bulky group at the inter-
face of the dimer of 1 led to compounds 6 and 8. It was found that
both changes were required to decrease crystal lattice energy
resulting in a substantial reduction in melting point. As predicted
by the general solubility equation, a significant increase in the
aqueous solubility of these two compounds was observed.
space group:
P
21/C, a = 18.936(3) Å, b = 5.114(2) Å, c = 19.549(3) Å, b =
= 0.234, F(000) = 920,
93.777(9)°, V = 1889.0(8) Å3, Z = 4, Dc = 1.559 g/cm3,
l
crystal size = 0.55 Â 0.30 Â 0.05 mm, R1 = 0.0665, Rint = 0.0402 based on 6770
independent reflections.
10. Lovering, F.; Bikker, J.; Humblet, C. J. Med. Chem. 2009, 52, 6752.
11. Hashimoto, Y.; Ishikawa, M. J. Med. Chem. 2011, 54, 1539.
12. Inhibitor enzymatic activity was determined utilizing full-length B-RafV600E
.
Inhibition of basal ERK phosphorylation in Malme-3M cells was used as the
mechanistic cellular assay and to drive the structure–activity relationships. For
complete experimental details regarding the enzymatic and mechanistic
cellular screening assays, please refer to Ref. 1.
13. For complete experimental details regarding aqueous solubility
determinations, please refer to Ref. 1.
14. Crystal structure determination of 6 was made by the University of California,
Berkeley, College of Chemistry, X-ray Crystallography Facility. Compound 6
was recrystallized from isopropyl ether. A colorless rod 0.15 Â 0.12 Â 0.08 mm
in size was mounted on a Cryoloop with Paratone oil. Data were collected in a
nitrogen gas stream at 200(2) K using phi and omega scans. Crystal-to-detector
distance was 60 mm and exposure time was 10 s per frame using a scan width
of 1.0°. Data collection was 97.4% complete to 67.00° in h. A total of 14251
reflections were collected covering the indices, À46 6 h 6 46, À6 6 k 6 4,
À34 6 l 6 34. 4271 reflections were found to be symmetry independent, with
an Rint of 0.0542. Indexing and unit cell refinement indicated a C-centered,
monoclinic lattice. The space group was found to be C2/c (No. 15). The data
were integrated using the Bruker SAINT software program and scaled using the
SADABS software program. Solution by direct methods (SIR-2004) produced a
complete heavy-atom phasing model consistent with the proposed structure.
All non-hydrogen atoms were refined anisotropically by full-matrix least-
squares (SHELXL-97). All hydrogen atoms were placed using a riding model.
Their positions were constrained relative to their parent atom using the
appropriate HFIX command in SHELXL-97. Crystal data and structure
Acknowledgements
The authors thank Jaroslaw Mazurek from Avantium for determi-
nation of the crystal structure of 1 and Antonio DiPasquale from The
University of California, Berkeley for determination of the crystal
structure of 6. The authors also thank Kevin Hunt, Yvan LeHuerou,
Li Ren, Stephen Schlachter, and Tony Tang for helpful discussions
and support.
References and notes
1. Wenglowsky, S.; Ren, L.; Ahrendt, K. A.; Laird, E. R.; Aliagas, I.; Alicke, B.;
Buckmelter, A. J.; Choo, E. F.; Dinkel, V.; Feng, B.; Gloor, S. L.; Gould, S. E.; Gross,
S.; Gunzner-Toste, J.; Hansen, J. D.; Hatzivassiliou, G.; Liu, B.; Malesky, K.;
Mathieu, S.; Newhouse, B.; Raddatz, N. J.; Ran, Y.; Rana, S.; Randolph, N.; Risom,
T.; Rudolph, J.; Savage, S.; Selby, L. T.; Shrag, M.; Song, K.; Sturgis, H. L.; Voegtli,
W. C.; Wen, Z.; Willis, B. S.; Woessner, R. D.; Wu, W. –I.; Young, W. B.; Grina, J.
ACS Med. Chem. Lett. 2011, 2, 342.
refinement for 6:
C44H52Cl2F2N10O7S2, monoclinic, space group: C2/c,
a = 39.3619(13) Å, b = 4.9943(2) Å, c = 29.1556(11) Å, b = 122.351(2)°, V =
4841.9(3) Å3, Z = 4, Dc = 1.380 g/cm3,
l = 0.2583, F(000) = 2104, crystal
size = 0.15 Â 0.12 Â 0.08 mm3, R1 = 0.0642, Rint = 0.0542 based on 4271
independent reflections.
2. Wenglowsky, S.; Ahrendt, K.; Buckmelter, A. J.; Feng, B.; Gloor, S. L.; Gradl, S.;
Grina, J.; Hansen, J. D.; Laird, E. R.; Lunghofer, P.; Mathieu, S.; Moreno, D.;