Synthesis of two potent glucocorticoid receptor agonists labeled with carbon-14 and stable isotopes

Article abstract of DOI:10.1002/jlcr.3349

Two potent glucocorticoid receptor agonists were prepared labeled with carbon-14 and with stable isotopes to perform drug metabolism, pharmacokinetics, and bioanalytical studies. Carbon-14 labeled (1) was obtained from an enantiopure alkyne (5) via a Sonogashira coupling to a previously reported 5-amino-4-iodo-[2-¹⁴C]pyrimidine [¹⁴C]-(6), followed by a base-mediated cyclization (1) in 72% overall radiochemical yield. Carbon-14 labeled (2) was prepared in five steps employing a key benzoic acid intermediate [¹⁴C]-(13), which was synthesized in one pot from enolization of trifluoromethylketone (12), followed by bromine-magnesium exchange and then electrophile trapping reaction with [¹⁴C]-carbon dioxide. A chiral auxiliary (S)-1-(4-methoxyphenyl)ethylamine was then coupled to this acid to give [¹⁴C]-(15). Propargylation and separation of diastereoisomers by crystallizations gave the desired diastereomer [¹⁴C]-(17) in 34% yield. Sonogashira coupling to iodopyridine (10) followed by cyclization to the azaindole [¹⁴C]-(18) and finally removal of the chiral auxiliary gave [¹⁴C]-(2) in 7% overall yield. For stable isotope syntheses, [¹³C₆]-(1) was obtained in three steps using [¹³C₄]-(6) and trimethylsilylacetylene-[¹³C₂] in 26% yield, while [²H₅]-(2) was obtained by first preparing the iodopyridine [²H₅]-(10) in five steps. Then, Sonogashira coupling to chiral alkyne (24) and cyclization gave [²H₅]-(2) in 42% overall yield.

Full text of DOI:10.1002/jlcr.3349

Research article
Received 24 July 2015,
Revised 21 August 2015,
Accepted 30 August 2015
Published online 22 September 2015 in Wiley Online Library
(wileyonlinelibrary.com) DOI: 10.1002/jlcr.3349
Synthesis of two potent glucocorticoid
receptor agonists labeled with carbon-14 and
stable isotopes
*
Bachir Latli, Jonathan T. Reeves, Zhulin Tan, Matt Hrapchak,
Jinhua J. Song, Carl B. Busacca, and Chris H. Senanayake
Two potent glucocorticoid receptor agonists were prepared labeled with carbon-14 and with stable isotopes to perform drug
metabolism, pharmacokinetics, and bioanalytical studies. Carbon-14 labeled (1) was obtained from an enantiopure alkyne
(5) via a Sonogashira coupling to a previously reported 5-amino-4-iodo-[2-14C]pyrimidine [14C]-(6), followed by a base-
mediated cyclization (1) in 72% overall radiochemical yield. Carbon-14 labeled (2) was prepared in five steps employing a
key benzoic acid intermediate [14C]-(13), which was synthesized in one pot from enolization of trifluoromethylketone (12),
followed by bromine–magnesium exchange and then electrophile trapping reaction with [14C]-carbon dioxide. A chiral
auxiliary (S)-1-(4-methoxyphenyl)ethylamine was then coupled to this acid to give [14C]-(15). Propargylation and separation
of diastereoisomers by crystallizations gave the desired diastereomer [14C]-(17) in 34% yield. Sonogashira coupling to
iodopyridine (10) followed by cyclization to the azaindole [14C]-(18) and finally removal of the chiral auxiliary gave [14C]-
(2) in 7% overall yield. For stable isotope syntheses, [13C6]-(1) was obtained in three steps using [13C4]-(6) and
trimethylsilylacetylene-[13C2] in 26% yield, while [2H5]-(2) was obtained by first preparing the iodopyridine [2H5]-(10) in five
steps. Then, Sonogashira coupling to chiral alkyne (24) and cyclization gave [2H5]-(2) in 42% overall yield.
Keywords: glucocorticoid mimics; radiosynthesis; carbon-14; carbon-13; deuterium
for the biological activity of these compounds. Its role in
Introduction
ligand–receptor interactions has been proposed on the basis of
The glucocorticoid receptor (GR) plays significant roles in
modeling studies to correspond to that of 11-β-OH of steroidal
vertebrate physiology owing to that fact that it is expressed in
GC, namely, hydrogen-bonding interaction with N564 (Asn 564)
in the active site, which has been recently confirmed by X-ray
most cell types and tissues.1 Glucocorticoids (GCs) are small
molecules that interact with this receptor.2 The anti-
inflammatory properties of GCs have been known for a long
time. GCs are widely used in the treatment of several
inflammatory diseases. For example, the development of
inhaled steroids and combination of inhaled steroids and β2
agonists led to many formulations currently on the market for
treating respiratory diseases. Fluticasone propionate and
salmeterol (Figure 1) are among the top ten most prescribed
and best-selling drugs in the world (www.medscape.com/
viewarticle/829246).
structure.10 The trifluoromethyl moiety affects the functional
activity. Analogs with this moiety behave as potential agonists.13
Compounds (1) and (2) are structurally similar. Compound (1) was
found to be at high risk of drug–drug interactions owing to its
potent cytochrome P-450 inhibition across multiple isoforms.14
Preliminary dose projections showed a potential for high clinical
dose requirements of this compound owing to the overall high
clearance and low bioavailability.14 The added modifications on
compound (2) were found to have a beneficial effect on
cytochrome P-450 profile and better metabolic stability and
aqueous solubility, and attenuate some of the other undesired
properties of compound (1).15 Both compounds are chiral, and
the pure enantiomers were reported to have twofold improved
potency against GR when compared with the racemic
mixtures.14,15
However, these therapies are fraught with a number of serious
side effects, like cross-reactivity with other steroid hormone
receptors. These complications often hamper high dose and
chronic administration. The search for non-steroidal drugs that
would have the desired anti-inflammatory actions of GC but with
significantly lower or no side effects remains an ongoing quest.3–13
Herein, we report the synthesis of two potent GR agonists
labeled with carbon-14 and with stable isotopes to aid in drug
metabolism, pharmacokinetics, and bioanalytical and other
studies (Figure 2).
Chemical Development, Boehringer Ingelheim Pharmaceuticals, Inc., 900
Ridgebury Road, PO Box 368, Ridgefield, CT, USA
*Correspondence to: Bachlir Latli, Chemical Development, Boehringer Ingelheim
Pharmaceuticals, Inc., 900 Ridgebury Road, PO Box 368, Ridgefield, CT, USA.
E-mail: bachir.latli@boehringer-ingelheim.com
As depicted in Figure 2, the quaternary center, trifluorome-
thylcarbinol, was reported to be an essential pharmacophore
J. Label Compd. Radiopharm 2015, 58 445–452
Copyright © 2015 John Wiley & Sons, Ltd.

B. Latli et al.
trimethylsilyl acetylene and n-butyl lithium at 0 °C in THF, to give
the alkyne (5) in 83% yield. Sonogashira coupling of this alkyne
to 5-amino-4-iodo-[2-14C]-pyrimidine [14C]-(6)17 gave [14C]-(7) in
89% radiochemical yield.12 Base-mediated cyclization using t-
BuOÀK+ in THF gave the diazaindole [14C]-(1) in 81%
radiochemical yield after two crystallizations from heptane-
isopropyl acetate.9 A total of 59.5 mCi of material was obtained
with a specific activity of 49.6 mCi/mmol and radiochemical
and chiral purities of more than 99% (Scheme 1).
Figure 1. Structure of fluticasone (steroid) and salmeterol (β2 agonist).
The same approach was applied to the synthesis of [13C6]-(1).
With the availability of [13C2]-trimethylsilylacetylene and 5-
amino-6-iodo[13C4]-pyrimidine,17 treatment of epoxide (3) with
the lithium salt of trimethylsilylacetylene[1,2-13C2] gave alcohol
[13C2]-(5) in 94% yield. Sonogashira coupling followed by
cyclization gave [13C6]-(1) in 92% and 30% yields, respectively
(Scheme 2).
Figure 2. Structure of compounds (1) and (2).
Synthesis of [14C2]-(2), [14C]-(2), and [2H5]-(2)
Similar to the preceding syntheses, the epoxide (8)16 was
used to prepare [14C2]-(2) in three steps (Scheme 3). However,
the first step gave very poor yield probably owing to the
instability of trimethylsilylacetylene-[1,2-14C2]. About 10 mCi of
[14C2]-(9) was obtained from 200 mCi of acetylene with
specific activity of 110 mCi/mmol. This compound was then
subjected as discussed before to the general Sonogashira
coupling followed by base-mediated cyclization using 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) in MeOH to give 2.9mCi
of the desired [14C2]-(2) after chromatographic purification
(Scheme 3).18
Results and discussions
Synthesis of [14C]-(1) and [13C6]-(1)
5-Amino-4-iodopyrimidine (6) is the most effective intermediate
to access carbon-14 labeled (1) with fewer radioactive steps and
more importantly avoid the synthesis of labeled chiral epoxide
(3). This chiral epoxide (3)16 was reacted with trimethylsilyl
lithium acetylide (4), which was prepared in situ from
While the aforementioned synthesis was short, not enough
material was obtained to cover the development studies. A
second synthesis was devised to furnish [14C]-(2) in five steps
with a specific activity of 58 mCi/mmol and a radiochemical
purity of 99.9% using carbon-14 labeled carbon dioxide
(Scheme 4). The key intermediate [14C]-(15) containing an N-(4-
methoxyphenyl)ethyl amide was first synthesized from
enolization of trifluoromethylketone (12)19 followed by
bromine–magnesium exchange, and then electrophile trapping
reaction with [14C]-carbon dioxide to [14C]-(13) was
accomplished in 71% radiochemical yield.19 The acid [14C]-(13)
was then converted to the acyl chloride using thionyl chloride
and reacted with (S)-1-(4-methoxyphenyl)ethylamine (14) to give
[14C]-(15) in 95% radiochemical yield. Addition of the lithium
derivative (16) gave a mixture of diastereomers. Crystallization
Scheme 1. Synthesis of [14C]-(1).
Scheme 2. Synthesis of [13C6]-(1).
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B. Latli et al.
Scheme 3. Synthesis of [14C2]-(2).
Scheme 4. Second synthesis of [14C]-(2).
from EtOAc acetate : heptane gave the desired diastereomer 2 N NaOD in deuterated water gave [2H5]-(20) in 99% yield.
[14C]-(17) in 34% radiochemical yield with more than 99% ee. Reduction of the nitro group at 50 psi hydrogen for 20 h followed
Sonogashira coupling with iodopyridine (10) followed by by reaction with di-tert-butyl dicarbonate to protect the amino-
cyclization gave [14C]-(18) in 37% radiochemical yield. Removal group gave [2H5]-(22) in 97% yield over two steps. Ortho
of chiral N-phenethyl amide moiety using aqueous HBr and metalation and subsequent iodination in anhydrous ethyl ether
acetic acid gave [14C]-(2) in 83% yield. Purification by preparative in the presence of tetramethylethylene diamine gave the iodo-
HPLC gave 37 mCi of the desired [14C]-(2) in 7% overall derivative [2H5]-(23) in 70% yield. Oxidation with sodium
radiochemical yield with 98% radiochemical purity, 99% chiral periodate in the presence of ruthenium trichloride in acetonitrile
purity, and a specific activity of 58 mCi/mmol.
and water gave [2H5]-(10) in 85% yield. General Sonogashira
In the synthesis of [2H5]-(2) (Scheme 5), we first prepared [2H5]- coupling reaction of this material with (24) gave [2H5]-(25) in
(10) in five steps and in 57% overall chemical yield starting from 99% yield.20 Finally, treatment with DBU in MeOH at 60 °C as
the commercially available [2H5]-ethanethiol. Thus, coupling seen before gave [2H5]-(2) in 95% yield after crystallization from
[2H5]-ethanethiol to 2-chloro-5-nitropyridine (19) using aqueous EtOAc.
J. Label Compd. Radiopharm 2015, 58 445–452
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B. Latli et al.
Scheme 5. Synthesis of [2H5]-(2).
acid stain. HPLC, gradient 20% to 100% MeCN/H2O (10 mM trifluoroacetic
acid) over 20 min; column, Zorbax Eclipse XDB C8 (4.6 mm × 150 mm,
Conclusion
Glucocorticoids play an important role in the regulation of the 5 μm). These conditions are used throughout this synthesis unless stated
otherwise. Disposable RediSep™ silica gel columns of different sizes were
immune system and, therefore, are widely used in the treatment
purchased from Isco, Inc. (Lincoln, NE, USA) and used for flash column
of inflammatory and immune diseases. However, because of
chromatography using Isco Combiflash. Liquid chromatography–mass
their many undesirable side effects, the search for non-steroidal
GC mimetics led to identification of compounds (1) and (2), with
compound (2) identified as a clinical candidate. The detailed
syntheses of these two potent GR agonists labeled with
spectrometry (LCMS) data were obtained using UPLC on Waters Acquity,
equipped with single quad detector, photodiode array detector, and
evaporative light scattering detector in the ESI+/À mode; column, C18
BEH (2.1 mm × 50 mm, 1.7 μm); column temperature, 60 °C; gradient,
90% A to 100% B in 1.19 min hold at 100% B to 1.77 min, flow rate
0.8 mL/min; A, 95% water, 5% acetonitrile, 0.05% formic acid; B,
carbon-14 and with stable isotopes are described. Compound
[14C]-(1) was prepared in two radioactive steps in 72% overall
yield and with a specific activity of 49.6 mCi/mmol and 99%
acetonitrile, 0.05% formic acid. Chiral HPLC was performed on Chiralpak
radiochemical and chiral purities. Carbon-13 labeled (1) was IA column, 235-nm detection, flow rate 2 mL/min, isocratic 70:30 v/v
heptane/i-PrOH, 10 min run. Both [2H5]-ethanethiol (99.7 at.% 2H) and
prepared in three chemical steps in 26% overall yield and with
[
13C2]-trimethylsilylacetylene (99.9 at.% 13C) were purchased from Isotec,
99% isotopic enrichment. Compound [14C]-(2) was prepared in
five radiochemical steps in 7% overall radiochemical yield and
with a specific activity of 58 mCi/mmol and radiochemical purity
of 99%. Deuterium labeled (2) was prepared in eight steps in
42% overall yield and with 99% isotopic enrichment. These
labeled compounds were used in drug metabolism and
pharmacokinetics and other studies.
an Aldrich company (Miamisburg, OH, USA). TMS-acetylene-[14C2] was
purchased from ViTrax (Placentia, CA, USA). Chiral epoxides (3) and (8)
with chiral purity exceeding 99% were obtained from in-house synthesis.
The rest of the reagents were purchased from Sigma-Aldrich Company
(St. Louis, MO, USA).
Synthesis of [14C]-(1)
(4R)-6-(5-Fluoro-2-methyl-phenyl)-6-methyl-4-trifluoromethyl-hept-
1-yn-4-ol (5)
Experimental procedures
Materials and methods
To a solution of trimethylsilylacetylene (400 mg, 4 mmol) in dry THF
Liquid scintillation counting was accomplished using a Beckman LS6500 (4 mL) was added a solution of n-BuLi (2.5 M solution in hexanes, 2 mL)
and ready safe™ cocktail (Beckman, Fullerton, CA, USA). NMR spectra were
recorded with a Bruker 400 MHz DPX or Bruker 500 MHz spectrometers
dropwise at 0 °C under nitrogen atmosphere. After stirring for 1 h,
epoxide (3) (1.1 g, 4 mmol) in dry dimethyl sulfoxide (8 mL) was added
(Bruker, Billerica, MA, USA) using deuterated solvents and dropwise, and the reaction was warmed gradually to room temperature
tetramethylsilane as the internal standard unless stated otherwise. Pre- and stirred for 14 h. A solution of aqueous NaOH (3 N, 3 mL) was then
coated thin-layer chromatography (TLC) sheets (silica gel 60F254) were added and stirred for 1 h at ambient temperature. The mixture was
obtained from EM Science (Gibbstown, NJ, USA). The developed plates cooled again to 0 °C, and aqueous HCl (2.75 N, 5 mL) was added. The
were visualized using 254-nm UV illumination or by phosphomolybdic
aqueous solution was extracted with EtOAc (100 mL × 3), and the
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B. Latli et al.
1-(5-Amino-pyrimidin[13C4]-4-yl)-6-(5-fluoro-2-methyl-phenyl)-6-methyl-
4(R)-trifluoromethyl-hept-1-yn-[1,2-13C2]-4-ol, [13C6]-(7)
combined extracts were washed with brine (100 mL), dried over MgSO4,
filtered, and concentrated under reduced pressure to give an oil that was
purified by flash chromatography using 40 g RediSep™ column and 20%
EtOAc : hexanes to give 0.74 g of a colorless oil in 83% yield. TLC:
Rf = 0.38 in 20% EtOAc : hexanes. 1H NMR (CDCl3) δ: 7.16 (dd, J = 2.73,
12.0 Hz, 1H), 7.11 (dd, J = 6.64, 8.31 Hz, 1H), 6.87 (dt, J = 2.73, 7.71 Hz,
1H), 2.56 (s, 3H), 2.45–2.56 (m, 2H), 2.31–2.42 (m, 2H), 1.82 (m, 1H), 1.60
(s, 3H), 1.56 (s, 3H).
A
mixture of [
13C4]-(6)17 (162 mg, 0.72 mmol), PdCl2(Ph3P)2 (5 mg,
7 μmol), and CuI (7 mg, 35 μmol) was first degassed. Dimethylformamide
(1 mL) was the added under nitrogen atmosphere, and the mixture was
cooled in an ice bath. The alkyne [13C2]-(5) (213 mg, 0.7 mmol) in TEA
(2 mL) was then added dropwise. The reaction was warmed gradually
to room temperature and stirred for 12 h. The dark mixture was treated
with a saturated solution of NH4Cl (6 mL), and the aqueous solution was
extracted with EtOAc (50 mL × 3). The combined extracts were washed
with brine, dried over MgSO4, filtered, and concentrated under reduced
pressure to give 0.35 g of a red-brown solid. Combiflash purification
using 10% to 20% EtOAc : CH2Cl2 gave 260 mg of red-brown foam in
92% yield, Rf = 0.44 in 10% MeOH/CH2Cl2. 1H NMR (CDCl3) δ: 8.56 (m,
J = 206 Hz, 1H), 8.23 (m, 1H), 7.16 (dd, 1H), 7.09 (dd, 1H), 6.85 (dt, 1H),
4.23 (brs, 2H), 2.97 (s, 3H), 2.60–2.80 (m, 2H), 2.54 (s, 3H), 1.56 (s, 3H).
13C NMR (CDCl3) δ: 162.53, 160.27, 148.30 (m), 142.38 (m), 142.15 (m),
135.00–132.81 (m), 94.53 (dd), (79.77, 78.73, 77.97, 76.93), 40.72, 38.74,
36.55, 31.49, 30.87, (26.74, 26.64, 26.07, 25.97), 22.66. LCMS: MH+
402.27 (100%).
1-(5-Amino[5-14C]pyrimidin-4-yl)-6-(5-fluoro-2-methyl-phenyl)-6-
methyl-4(R)-trifluoromethyl-hept-1-yn-4-ol, [14C]-(7)
A
mixture of 5-amino-4-iodo[2-14C]pyrimidine, 14C]-(6)17 (435 mg,
[
1.97 mmol, 95 mCi), PdCl2(Ph3P)2 (14 mg, 0.02 mmol), and CuI (19 mg,
0.1 mmol) in degassed dimethylformamide (5 mL) was added under
nitrogen atmosphere to alkyne (5) (595 mg, 1.97 mmol) in degassed
triethylamine (TEA, 10 mL) dropwise at 0 °C. The reaction was warmed
gradually to room temperature and stirred for 48 h. The dark mixture
was treated with a saturated solution of NH4Cl (25 mL), and the aqueous
solution was extracted with EtOAc (100 mL × 3). The combined extracts
were washed with brine (100 mL), dried over MgSO4, filtered, and
concentrated under reduced pressure to give a red-brown solid.
Combiflash purification using 10% to 20% EtOAc : CH2Cl2 and 40 g
RediSep™ gave 696 mg of orange foam (73.3 mCi) in 89% radiochemical
yield, Rf = 0.44 in 10% MeOH/CH2Cl2.
(R)-1,1,1-Trifluoro-4-(5-fluoro-2-methyl-phenyl)-4-methyl-2-(5H-pyrro-
lo[3,2-d]pyrimidin-[13C6]-6-ylmethyl)-pentan-2-ol, [13C6]-(1)
To the alkyne [13C6]-(7) (245 mg, 0.6 mmol) in THF (3 mL) was added t-
BuOK (150 mg, 1.2 mol) in one portion at 0 °C under nitrogen. After 4 h,
brine (3 mL) was added, and the mixture was extracted with EtOAc
(10 mL × 3). The combined extracts were washed with brine (20 mL),
dried over MgSO4, filtered, and concentrated under reduced pressure
to give 245 mg of foam. Combiflash purification on 40 g RediSep™ and
10% to 30% EtOAc : CH2Cl2 gave 70 mg of pure material in 30% yield,
(R)-1,1,1-Trifluoro-4-(5-fluoro-2-methyl-phenyl)-4-methyl-2-(5H-
pyrrolo[3,2-d][2-14C]pyrimidin-6-ylmethyl)-pentan-2-ol, [14C]-(1)
To a solution of [14C]-(7) (696 mg, 1.76 mmol, 73 mCi) in THF (5 mL) was
added t-BuOK (434 mg, 3.87 mmol) in one portion at 0 °C under nitrogen.
After stirring for 2 h, brine (5 mL) was added, and the mixture was
warmed to room temperature and extracted with EtOAc (10 mL × 3).
The combined extracts were washed with brine (20 mL), dried over
MgSO4, filtered, and concentrated under reduced pressure to give foam.
Combiflash purification on 40 g RediSep™ and 0% to 100% EtOAc : CH2Cl2
gave 121 mg of not so pure product and 400 mg of the desired product,
Rf = 0.42 in 10% MeOH/CH2Cl2. The pure material was further crystallized
twice from isopropyl acetate : heptane (1.5 mL each) to give 325 mg of a
white solid. HPLC: Rt = 11.4 min, radiopurity 99%, and chiral purity 99%.
Total radioactivity 59.5 mCi, or 81.4% radiochemical yield. 1H NMR
(MeOH-d4) δ: 8.71 (s, 1H), 8.67 (s, 1H), 7.16 (dd, J = 12, 2 Hz, 1H), 7.07 (m,
1H), 6.81 (m, 1H), 6.29 (s, 1H), 2.91 (d, J = 15 Hz, 1H), 2.75 (d, J = 15 Hz,
1H), 2.63 (d, J = 15 Hz, 1H), 2.52 (s, 3H), 2.12 (d, J = 16 Hz, 1H), 1.69 (s,
3H), 1.44 (s, 3H).
1
Rf = 0.42 in 10% MeOH/CH2Cl2. HPLC: Rt = 11.327 min. H NMR (CDCl3) δ:
8.90 (dt, J = 202.46, 9.84 Hz, 1H), 8.70 (dm, J = 181.59 Hz, 1H), 7.16 (dd,
J = 6.58, 8.14 Hz, 1H), 7.07 (dd, J = 6.58, 8.41 Hz, 1H), 6.86 (dt, J = 2.65,
7.78 Hz, 1H), 6.43 (dm, J = 176.32 Hz, 1H), 2.94–3.12 (m, 2H), 2.45 (dd,
J = 15.72, 75.03 Hz, 2H), 2.38 (s, 3H), 1.63 (s, 3H), 1.49 (s, 3H). 13C NMR
(CDCl3) δ: 162.55, 160.13, 150.29 (t, J = 53.71 Hz), 146.31 (d, J = 69.60 Hz),
143.02 (d, J = 69.6 Hz), 138.081 (d, J = 66.91 Hz), 134.82, 134.74, 131.82,
127.55, 113.64 (m), 103.12 (m), 53.43, 42.56, 38.73, 34.20, 33.76, 31.66,
30.81, 22.41. LCMS: MH+ = 402.23 (100%). High-resolution mass
spectrometry: calc. 402.1894, found 402.1898.
Synthesis of [14C2]-(2)
Synthesis of [13C6]-(1)
5-Fluoro-2-(R)-3-hydroxy-1,1-dimethyl-3-trifluoromethyl-hex-5-ynyl-
[14C2])-benzamide, [14C2]-(9)
6-(5-Fluoro-2-methyl-phenyl)-6-methyl-4-trifluoromethyl-hept-1-yn
[1,2-13C2]-4-ol, [13C2]-(5)
To a solution of trimethylsilylacetylene[1,2-14C2] (200 mCi, 1.8 mmol) in
To a solution of trimethylsilylacetylene[1,2-13C2] (102 mg, 1 mmol) in dry anhydrous dimethoxyethylene (DME, 10 mL) was added n-BuLi (2.4 M in
THF (1 mL) was added a solution of n-BuLi (2.5 M solution in hexanes,
0.44 mL) dropwise at 0 °C under nitrogen atmosphere. After stirring for
1 h, epoxide (3) (280 mg, 1 mmol) in dry dimethyl sulfoxide (2 mL) was
added dropwise, and the reaction was warmed gradually to room
temperature overnight. A solution of NaOH (3.0 N, 0.6 mL) was then
added and stirred for 1 h. The reaction was cooled again to 0 °C, and
aqueous HCl (2.75 N, 1 mL) was added. The aqueous solution was
THF, 0.84 mL, 2 mmol) at À15 °C. The resulting yellow solution was
warmed to room temperature and stirred for 1 h. A solution of epoxide
(8) (0.52 g, 1.7 mmol) in DME (5 ML) was cooled to below À40 °C, and a
solution of dibutyl magnesium (1 M in heptane, 1 mL) was added
dropwise. After stirring for 1 h at this temperature, the resulting lithium
acetylide was cooled to À20 °C and added via cannulation to the flask
containing the epoxide (8). The reaction was left to warm gradually to
extracted with EtOAc (50 mL × 3), and the combined extracts were room temperature and stirred for 2 h. After cooling to À10 °C, MeOH
washed with brine (50 mL), dried over MgSO4, filtered, and concentrated
under reduced pressure to give an oil that was purified by flash
chromatography using 40 g RediSep™ and 20% EtOAc : hexanes to give
285 mg of a slight yellow oil in 94% yield, Rf = 0.38 in 20% EtOAc :
hexanes. 1H NMR (CDCl3) δ: 7.16 (dd, J = 2.73, 12.0 Hz, 1H), 7.11 (dd,
was added (10 mL), and the mixture was warmed to 0 °C in an ice bath.
A solution of aqueous NaOH (1 N, 15 mL) was added dropwise, and the
mixture was warmed to room temperature and stirred overnight. A
saturated solution of NH4Cl was added (50 mL) and extracted with EtOAc
(20 mL × 3). The combined extracts were dried over MgSO4, filtered, and
J = 6.64, 8.31 Hz, 1H), 6.87 (dt, J = 2.73, 7.71 Hz, 1H), 2.56 (s, 3H), 2.45– concentrated in vacuo to give brown oil. Purification by silica gel
2.56 (m, 2H), 2.31–2.42 (m, 2H), 1.82 (m, 1H), 1.60 (s, 3H), 1.56 (s, 3H).13C
NMR (CDCl3) δ: 162.54, 160.12, (146.99, 146.94), (134.65, 134.57), 131.66,
127.06, 124.20, (114.78, 114.56), (113.35, 113.15), (78.46, 76.73, 73.97,
71.83), 51.92, 40.27, 38.67, 31.36, 30.82, (25.74, 25.63, 25.09, 24.97), 22.66.
chromatography using 40 g disposable column wetted with CH2Cl2 and
using up to 20% EtOAc : CH2Cl2 gave the desired product with some
polar impurities. A second purification by HPLC gave 9.8 mCi of desired
product with more than 98% radiochemical purity.
J. Label Compd. Radiopharm 2015, 58 445–452
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B. Latli et al.
{4-[(R)-6-(2-Carbamoyl-4-fluoro-phenyl)-4-hydroxy-6-methyl-4-tri- 5-Fluoro-N-[(S)-1-(4-methoxy-phenyl)-ethyl]-2-(4,4,4-trifluoro-1,1-di-
fluoromethyl-hept-1-ynyl-[1,2-14C2]-]-6-ethanesulfonyl-pyridin-3-yl}- methyl-3-oxo-butyl)-benzamide-[14C], [14C]-(15)
carbamic acid tert-butyl ester, [14C2]-(11)
The acid [14C]-(13) (354 mCi, 6.1 mmol) in SOCl2 (6 mL) was heated to 55 °
C and stirred for 4 h. Excess thionyl chloride was removed in vacuo, and
the residue was dissolved in THF (4 mL) and cooled to 0 °C. (S)-1-(4-
Methoxyphenyl)ethylamine (14) (0.92 mL, 6.2 mmol) and TEA (2.9 mL,
21 mmol) were added at 0 °C. The reaction was warmed to room
temperature and stirred for 2 h. The reaction was then concentrated in
vacuo, and the residue was purified by silica gel chromatography using
35:1 CH2Cl2/MeOH to give 335 mCi of product in 95% yield.
A solution of TEA (64 μL, 0.46 mmol) in MeCN (3 mL) was degassed by
bubbling argon through it for 20 min and then added to a mixture of the
aforementioned acetylene derivative [14C2]-(9) (9.8 mCi, SA = 110 mCi/
mmol), bis(acetonitrile)dichloropalladium (II) (2 mg, 8 μmol), CuI (5.2 mg,
27 μmol), and (10) (40 mg, 94 μmol) at room temperature. The resulting
dark mixture was stirred for 12 h. The mixture was concentrated in vacuo,
and the residue was dissolved in EtOAc and washed with water (5 mL)
and brine (10 mL), dried over Na2SO4, filtered, and concentrated in vacuo.
Purification by flash chromatography (12 g disposable silica gel column)
using CH2Cl2 and then 20% EtOAc/CH2Cl2 gave 21 mg (3.8 mCi) of the
desired product in 39% yield, which was used as it is in the next step.
5-Fluoro-2-((R)-3-hydroxy-1,1-dimethyl-3-trifluoromethyl-hex-5-ynyl)-
N-[(S)-1-(4-methoxy-phenyl)-ethyl]-benzamide-[14C], [14C]-(17)
A solution of 1-trimethylsilylpropyne (1.3 mL, 8.8 mmol) in 50 mL of THF
was treated dropwise over 15 min with n-BuLi (3.6 mL, 8.8 mmol, 2.5 M/
hexanes) at À20 °C and stirred for 1 h and then treated with a solution
of zinc bromide (1.45 g, 6.4 mmol) in THF (5 mL), keeping the
temperature between À20 and À15 °C. The reaction mixture was stirred
for 1 h at À20 °C. A solution of [14C]-(15) (335 mCi, 5.78 mmol) in THF
(5 mL) was added slowly, keeping the temperature between À20 and
À15 °C. After 1 h, the reaction mixture was quenched with MeOH
(7 mL) and concentrated to 1/3 volume. MeOH (7 mL) was added,
followed by sodium methoxide (270 mg of Na and 1.5 mL of MeOH).
The reaction mixture was stirred at room temperature for 1 h; 85%
phosphoric acid (0.8 mL) in 50 mL of water was added. An additional
20 mL of water was added followed by 20 mL of EtOAc, and the slurry
was stirred for 1 h and filtered. The solid (zinc oxide) was washed with
4 mL of water and then washed with EtOAc (10 mL). The filtrates were
combined, and the layers were separated. The aqueous layer was
extracted with EtOAc (30 mL × 3). The combined organic extracts were
dried over Na2SO4, filtered, and concentrated. Crystallization from EtOAc
(8 mL) and heptane (1 mL) at room temperature overnight gave a white
solid. The solid was filtered and dried to give 962 mg of product or
115.4 mCi of [14C]-(17) in 34% radiochemical yield.
2-[(R)-3-(5-Ethanesulfonyl-1H-[2,3-14C]pyrrolo[2,3-c]pyridin-2-ylme-
thyl)-4,4,4-trifluoro-3-hydroxy-1,1-dimethyl-butyl]-5-fluoro-benzamide,
[14C2]-(2)
To a solution of [14C2]-(11) (21 mg, 0.034 mmol) in MeOH (2 mL) was
added DBU (40 μL, 0.27 mmol) in one portion at room temperature. The
resulting solution was heated to 60 °C and stirred for 2.5 h. HPLC showed
no starting material. The reaction was concentrated under a stream of
nitrogen and then dissolved in EtOAc (5 mL) and washed with a
saturated solution of NH4Cl (3 mL), dried over Na2SO4, filtered, and
concentrated overnight under a stream of nitrogen to give 21 mg of a
residue. A sample of 14 mg of unlabeled (2) was added, and the mixture
was dissolved in 10% MeOH/CH2Cl2 and then purified using a 12-g
disposable silica gel column. An impurity remained that eluted just above
the desired product (Rf = 0.65 for impurity; Rf = 0.52 for desired product in
50% EtOAc : CH2Cl2). A second purification using another 12 g silica gel
column and 50% EtOAc : CH2Cl2 gave 32 mg of product as white solid,
Rf = 0.27 in 10% MeOH/CH2Cl2. HPLC showed the product to be 92% pure
(Rt = 10.31 min) with a major impurity (5%) at 12.74 min. The product was
crystallized from absolute ethanol (1.0 mL) to give a grain-like white solid,
which was washed with ethanol (0.5 mL × 2) to give 12 mg of the desired
product and 15 mg of yellowish mother liquor. The mother liquor was
concentrated, and the residue was dissolved in CH2Cl2 and purified by
prep-TLC (0.5 mm) using 10% MeOH/CHCl3. The layer corresponding to
the product was scraped and extracted with 10% MeOH/CHCl3, filtered,
and concentrated in vacuo. The white solid was further dried under
reduced pressure at 35 °C to give 13 mg of material with radiochemical
purity of 98.8%. A total of 25 mg of combined product was obtained in
52% yield over two steps, and with a specific activity of 46 mCi/mmol.
2-[(R)-3-(5-Ethanesulfonyl-1H-pyrrolo[2,3-c]pyridin-2-ylmethyl)-4,4,4-
trifluoro-3-hydroxy-1,1-dimethyl-butyl]-5-fluoro-N-[(S)-1-(4-methoxy-
phenyl)-ethyl]-benzamide, [14C]-(18)
[
14C]-(17) (115.4 mCi, 1.99 mmol) and the iodopyridine derivative (10)
(0.866 g, 2.04 mmol) in degassed MeOH (10 mL) were stirred under N2
atmosphere. 1,4-Diazabicyclo(2,2,2)octane (430 μL, 3.87 mmol) and
allylpalladium chloride dimmer (4 mg, 10.71 μmol) as a slurry in degassed
MeOH (5 mL) were added. The reaction is heated to 50 °C. After 9 h, DBU
(450 μL, 3.0 mmol) was added. All solid dissolved, and the yellow solution
is heated up to 50 °C for 3 h. After cooling to room temperature, the
reaction was concentrated in vacuo, and the residue was purified by silica
gel chromatography using 30:1 CH2Cl2/MeOH. This residue was further
purified using prep-TLC and 10:1 CH2Cl2/acetone to give 44.6 mCi in
37% radiochemical yield and with a specific activity of 58 mCi/mmol.
Synthesis of [14C]-(2)
5-Fluoro-2-(4,4,4-trifluoro-1,1-dimethyl-3-oxo-butyl)-benzoic acid
[carboxyl-14C], [14C]-(13)
2-[(4R)-4-{[5-(Ethylsulfonyl)-1H-pyrrolo[2,3-c]pyridin-2-yl]methyl}-
5,5,5-trifluoro-4-hydroxy-2-methylpentan-2-yl]-5-fluoro-benzamide-
[14C], [14C]-(2)
In a round-bottomed flask, sodium hydride (300 mg, 60 wt.% dispersion in
mineral oil, 2.5 mmol) was added under N2 atmosphere. Anhydrous THF
(6 mL) was then added, and the mixture was stirred while cooling to
internal temperature ~0–5 °C. Then, a solution of trifluoromethylketone
(12) (2.21 g, 6.2 mmol) in THF (6 mL) was added at a rate that internal
temperature does not exceed 10 °C. The mixture was stirred at 25 °C for
[
14C]-(18) (44.6 mCi, 0.77 mmol) and acetic acid (2.5 mL) were stirred at
room temperature. An off-white slurry is obtained. A solution of 48%
aqueous HBr (1.3 mL) was added. The off-white slurry becomes red. The
20 h. The mixture was cooled to 0–5 °C, and iso-propylmagnesium reaction was heated to 80 °C. It becomes homogeneous upon warming.
chloride lithium chloride complex (5.1 mL, 1.3 M in THF) was added at a
rate that internal temperature does not exceed 20 °C in 5 min, and then
1,4-dioxane (1.7 mL) was added. The mixture was stirred at room
After stirring at this temperature for 7 h, the reaction was cooled to room
temperature overnight. After concentration in vacuo, the residue was
dissolved in MeOH (20 mL) and treated with 1 N KOH (5 mL). The pH
temperature for 4 h. [14C]-CO2 generated from 500 mCi of BaCO3 was then was adjust to 7, and the mixture was filtered, dried, and purified by flash
added to the reaction at À40 °C. The reaction was stirred below À20 °C for
chromatography using 15:1 CH2Cl2/MeOH to give 37 mCi of material in
2 h before aqueous 3 N HCl (12 mL) was added. The mixture was warmed 83% radiochemical yield with a specific activity of 58 mCi/mmol and
to room temperature and extracted with toluene (20 mL × 3), filtered, and 99% radiochemical purity and 99% chiral purity. 1H NMR (MeOH-d4) δ
concentrated in vacuo to give 354 mCi (71% yield) of crude product, 8.67 (s, 1H), 8.20 (s, 1H), 7.56 (dd, J = 9 Hz, J = 5 Hz, 1H), 7.10 (dd,
which was used as it is in the next step.
J = 9 Hz, J = 3 Hz, 1H), 7.02 (ddd, J = 9 Hz, J = 9 Hz, J = 3 Hz, 1H), 6.47 (s,
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Copyright © 2015 John Wiley & Sons, Ltd.
J. Label Compd. Radiopharm 2015, 58 445–452

B. Latli et al.
1H), 3.34 (q, J = 7 Hz, 2H), 3.17 (d, J = 15 Hz, 1H), 3.02 (d, J = 15 Hz, 1H),
2.49 (d, J = 15 Hz, 1H), 2.42 (d, J = 15 Hz, 1H), 1.61 (s, 6H), 1.19 (t,
J = 7 Hz, 3H).
1.53 (s, 9H). 13C NMR (CDCl3) δ: 152.41, 150.30, 140.13, 138.81, 131.85,
98.51, 81.98, 28.43, 24.15 (pent. J = 22.13 Hz), 13.85 (sept, J = 20.12 Hz).
(6-Ethyl-[2H5]-sulfonyl-4-iodopyridin-3-yl)carbamic acid tert-butyl es-
ter, [2H5]-(10)
Synthesis of [2H5]-(2)
To a solution of [2H5]-(23) (1.6 g, 4.2 mmol) in acetonitrile (26 mL) and
water (12 mL) was added sodium (meta)periodate (1.94 g, 9 mmol) and
RuCl3 (50 mg, 0.24 mmol) at room temperature. The resulting mixture
(dark) was stirred overnight. LCMS shows only one product:
MH+ = 418.57 (100%), Rt = 1.61 min. Ether (300 mL) was added followed
by aqueous NaCl (200 mL). The organic phase was removed, and the
aqueous solution was extracted with another 300 mL of ether. The
combined extracts were dried over MgSO4, filtered, and concentrated
in vacuo to give 2.22 g of a solid material. Purification by Combiflash
using a 120-g disposable silica gel column and a gradient 0% to 20%
EtOAc in CH2Cl2 gave 1.4 g of a white solid in 85% yield. 1H NMR (CDCl3)
δ: 9.34 (s, 1H), 8.42 (s, 1H), 7.03 (s, 1H), 1.56 (s, 9H). 13C NMR (CDCl3) δ:
151.37, 149.76, 140.13, 139.87, 132.67, 98.30, 82.97, 46.03 (pent,
J = 21.13 Hz), 28.41, 5.99 (sept, J = 20.13 Hz).
2-Ethyl-[2H5]-sulfanyl-5-nitropyridin, [2H5]-(20)
To a mixture of [2H5]-ethanethiol (5 g, 74.5 mmol) in THF (115 mL) and
aqueous NaO2H (2 N, 46.5 mL) was added 2-chloro-5-nitropyridine (19)
(9.84 g, 61.4 mmol) in one batch at 0 °C. After 2 h, the starting material
was consumed. TLC (10% EtOAc : hexanes), Rf = 0.24 (starting material)
and Rf = 0.36 (product). Water was added (150 mL) and extracted with
EtOAc (100 mL × 3). The organic layer was washed with brine (100 mL),
dried over MgSO4, filtered, and concentrated in vacuo to give 11.71 g
of an off-white solid in 99% yield. LCMS (ESI+): 95% to 5% water/MeCN
gradient (0.1 formic acid): MH+ = 190.66 (100%), Rt = 1.29 min. 1H NMR
(CDCl3) δ: 9.23 (d, J = 2.56 Hz, 1H), 8.21 (dd, J = 2.56, 9.48 Hz, 1H), 7.26
(d, J = 9.48 Hz, 1H). 13C NMR (CDCl3) δ: 168.17, 145.05, 140.95, 130.22,
121.41, 24.21 (pent, J = 21.13 Hz), 13.22 (sept, J = 19.12 Hz).
5-Fluoro-2-((R)-3-hydroxy-1,1-dimethyl-3-trifluoromethyl-hex-5-ynyl)-
benzamide, (24)
6-Ethyl-[2H5]-sulfanyl-pyridin-3-ylamine, [2H5]-(21)
A mixture of [2H5]-(20) (11.56 g, 61.1 mmol) and 10% Pd/C (2 g) in
absolute ethanol (200 mL) was stirred under 50 psi of hydrogen for 20 h
in a Parr apparatus. TLC (10% EtOAc : hexanes) showed no starting
material. The reaction was filtered through a short pad of Celite® and
concentrated in vacuo to half its volume and then used as an ethanolic
solution in the next step. LCMS (ESI+): MH+ = 160.38 (100%), Rt = 0.77 min.
1H NMR (CDCl3) δ: 8.21 (d, J = 2.61 Hz, 1H), 7.68 (dd, J = 2.61, 8.65 Hz, 1H),
7.14 (d, J = 8.65 Hz, 1H), 6.35 (s, 2H). 13C NMR (CDCl3) δ: 151.3, 145.10,
138.7, 127.3, 24.2 (pent. J = 22.13 Hz), 14.31 (sept, J = 20.12 Hz).
To a solution of trimethylsilylacetylene (1.2 g, 11.7 mmol) in anhydrous
DME (10 mL) was added n-BuLi (2.4 M in THF, 5 mL, 12 mmol) at À15 °C.
The resulting yellow solution was warmed to room temperature and
stirred for 1 h. A solution of epoxide (8) (0.52 g, 1.7 mmol) in DME (5 mL)
was cooled to below À40 °C, and a solution of dibutyl magnesium (1 M
in heptane, 1 mL) was added dropwise. After stirring for 1 h at this
temperature, the lithium acetylide was cooled to À20 °C and added via
cannulation to the epoxide flask. The reaction was left to warm gradually
to room temperature and stirred for 2 h. After cooling to À10 °C, MeOH
was added (10 mL), and the mixture was warmed to 0 °C in an ice bath.
A solution of NaOH in water (15 mL, 1 N) was added dropwise, and the
mixture was warmed to room temperature and stirred overnight. A
solution of NH4Cl was added (50 mL) and extracted with EtOAc
(50 mL × 3). The combined extracts were dried over MgSO4, filtered, and
concentrated in vacuo to give 700 mg of brown oil, which solidified upon
standing at room temperature. Purification by silica gel chromatography
using 40 g disposable column wetted with CH2Cl2 and using up to 20%
EtOAc : CH2Cl2 gave 440 mg of orange solid with Rf = 0.5 in 10%
MeOH/CHCl3. 1H NMR (CDCl3) δ: 7.51 (m, 1H), 7.10 (m, 1H), 7.02 (m, 1H),
6.33 (s, 1H), 6.06 (s, 1H), 5.76 (s, 1H), 5.30 (s, 1H), 2.51 (m, 2H), 2.42 (AB
quart, J = 15.01, 50.77 Hz, 2H), 2.08 (s, 1H), 1.66 (s, 3H), 1.44 (s, 3H). LCMS:
Rt = 1.61 min, 95%, MH+ = 332.72.
(6-Ethyl-[2H5]-sulfanyl-pyridin-3-yl)carbamic acid tert-butyl ester, [2H5]-
(22)
To a solution of [2H5]-(21) from last reaction in ethanol (100 mL) was
added di-tert-butyl dicarbonate (17 g, 63 mmol) in one portion at room
temperature. The resulting solution was stirred overnight. The reaction
was then concentrated under reduced pressure, and the residue was
dissolved in EtOAc (300 mL) and washed with a saturated solution of
NaHCO3 (100 mL) and brine (50 mL), dried over MgSO4, filtered, and
concentrated in vacuo to give 16.75 g of a viscous oil. Purification by
Combiflash using 120 g disposable column and a gradient 0% to 20%
EtOAc : CH2Cl2 gave 15.6 g of a viscous oil in 98% yield. The product
solidified upon standing at room temperature. TLC in 10 MeOH/CHCl3:
starting amine, Rf = 0.33 (turned brown in the air); product, Rf = 0.60.
LCMS (ESI+): MH+ = 260.48 (100%), Rt = 1.70 min. 1H NMR (CDCl3) δ: 8.31
(d, J = 2.61 Hz, 1H), 7.78 (s, 1H), 7.12 (d, J = 8.67 Hz, 1H), 6.74 (s, 1H), 1.54
{4-[(R)-6-(2-Carbamoyl-4-fluoro-phenyl)-4-hydroxy-6-methyl-4-tri-
fluoromethyl-hept-1-ynyl]-6-ethane-[2H5]-sulfonyl-pyridin-3-yl}-car-
(br s, 9H). 13C NMR (CDCl3) δ: 152.85, 140.30, 131.90, 127.06, 122.51, bamic acid tert-butyl ester, [2H5]-(25)
81.09, 28.28, 24.28 (pent. J = 22.13 Hz), 13.57 (sept, J = 20.12 Hz).
A solution of TEA (0.85 mL, 6.1 mmol) in acetonitrile (5 mL) was degassed
(6-Ethyl-[2H5]-sulfanyl-4-iodopyridin-3-yl)carbamic acid tert-butyl
by bubbling argon through it for 15 min and added via cannulation to a
mixture of the alkyne derivative (24) (394 mg, 1.19 mmol), the labeled
iodopyridine [2H5]-(10) (0.5 g, 1.2 mmol), bis(acetonitrile)dichloropa-
ester, [2H5]-(23)
To a solution of [2H5]-(22) (15.5 g, 61 mmol) in anhydrous ether (150 mL) lladium (II) (5 mg, 0.02 mmol), and cuprous iodide (69 mg, 0.355 mmol).
was added a solution of n-BuLi in hexanes (2.4 M, 60 mL) at À78 °C under The resulting dark solution was stirred for 3 h at room temperature. HPLC,
nitrogen dropwise. The resulting solution was warmed to 0 °C in an ice
in 22 min run, shows that the reaction was over. A new product at
bath and stirred for 3 h. The dark reaction was cooled again to À78 °C, 14.27 min was detected, with the starting material at 10.79 min. The
and iodine (34 g, 134 mmol) dissolved in anhydrous ether (150 mL) was reaction was concentrated in vacuo, and the residue was dissolved in
added dropwise with stirring. The reaction was warmed gradually to EtOAc (20 mL) and washed with water (20 mL). The organic phase was
room temperature and stirred overnight.
ammonium chloride (350 mL) was added, and the ether layer was an orange residue. Purification using 40 g disposable column and up to
separated; washed with a solution of Na2SO3, water (50 mL), and brine 20% EtOAc : CH2Cl2 gave 691 mg of yellow foam. TLC (12%
(50 mL); and dried over MgSO4. Filtration and concentration in vacuo MeOH/CHCl3): product, Rf = 0.43; starting material, Rf = 0.37. 1H NMR
A solution of saturated dried over MgSO4, filtered, and concentrated in vacuo to give 0.91 g of
gave 20.45 g of dark viscous oil. A portion of this crude product (10 g)
(CDCl3) δ: 9.49 (s, 1H), 8.29 (s, 1H), 7.56 (s, 1H), 7.48 (m, 1H), 7.04 (m,
2H), 6.51–6.70 (m, 2H), 6.20 (s, 1H), 3.48 (m, 1H), 2.76 (AB quart,
was purified by Combiflash to give 1.6 g of the desired product in 70%
yield based on reacted starting material. A batch of 4 g of unreacted J = 17.51, 42.6 Hz, 2H), 2.40–2.61 (m, 2H), 1.65 (s, 6H), 1.54 (s, 9H). 13C
starting material was recovered. LCMS: MH+ = 386.45 (100%), NMR (CDCl3) δ: 175.64, 161.72, 159.24, 151.65, 148.68, 140.18, 139.75,
Rt = 1.93 min. 1H NMR (CDCl3) δ: 9.21 (s, 1H), 8.41 (s, 1H), 7.32 (s, 1H),
139.04, 136.29, 130.17, 125.02, 119.14, 116.94, 116.34, 115.51, 115.28,
J. Label Compd. Radiopharm 2015, 58 445–452
Copyright © 2015 John Wiley & Sons, Ltd. www.jlcr.org

B. Latli et al.
98.81, 82.47, 75.42 (q, J = 27.17 Hz), 45.13, 36.96, 33.92, 33.15, 28.12, 27.13.
LCMS: Rt = 1.83 min (99%), MH+ = 621.85. HPLC: Rt = 14.36 min, 99%.
T. N. Fadra, R. Nelson, S. Goldrick, L. Zuvela-Jelaska, D. Souza, J.
Pelletier, R. Dinallo, M. Panzenbeck, C. Torcellini, H. Lee, E. Pack, C.
Harcken, G. Nabozny, D. S. Thomson, Bioorg. Med. Chem. Lett.
2011, 21, 6842–6851.
2-[(S)-3-(5-Ethane-[2H5]-sulfonyl-1H-pyrrolo[2,3-c]pyridin-2-ylme-
thyl)-4,4,4-trifluoro-3-hydroxy-1,1-dimethyl-butyl]-5-fluoro-benza-
mide, [2H5]-(2)
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Cooper, A. Craven, J. R. Gray, D. House, T. I. Jack, S. P. Keeling, S. J.
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Nelson, C.-K. Shih, A. J. Kukulka, Z. Paw, P. Reilly, R. Deleon, M.
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To a solution of [2H5]-(25) (690 mg, 1.11 mmol) in MeOH (10 mL) was
added DBU (0.5 mL, 3.34 mmol) in one portion at room temperature. The
resulting solution was heated to 60 °C and stirred for 2 h. HPLC showed
no starting material. The reaction was concentrated under reduced
pressure and then dissolved in EtOAc (50 mL) and washed with a saturated
solution of NH4Cl (30 mL), dried over MgSO4, filtered, and concentrated in
vacuo to give 0.58 g of a yellow solid. TLC (10% MeOH/CHCl3): starting
material, Rf = 0.40; product, Rf = 0.27. The solid was dissolved in boiling
EtOAc (6 mL) and left to cool to room temperature to give a white solid.
Filtration and drying gave 550 mg of material. HPLC: Rt = 9.79 min, 99%.
LCMS: MH+ = 521.81 as the only ion peak, Rt = 1.51 min. 1H NMR (MeOH-
d4) δ: 8.68 (s, 1H), 8.21 (s, 1H), 7.57 (dd, J = 5.42, 8.94 Hz, 1H), 7.11 (dd,
J = 2.91, 8.76 Hz, 1H), 7.03 (dt, J = 2.91, 12.70 Hz, 1H), 6.48 (s, 1H), 4.11 (q,
J = 7.15 Hz, 2H, EtOAc), 3.12 (Abq, J = 14.97, 60.27 Hz, 2H), 2.46 (d,
J = 15.41 Hz, 2H), 2.02 (s, 3H, EtOAc), 1.62 (s, 6H), 1.25 (t, J = 7.15 Hz, 3H,
EtOAc). 13C NMR (MeOH-d4) δ: 176.15, 171.50, 161.65, 159.20, 143.70,
142.17, 139.94, 113.88, 134.45, 133.53, 132.54, 130.43, 130.36, 127.38,
124.51, 115.40, 115.16, 102.91, 76.06 (q, J = 80.50 Hz), 60.05, 45.02, 37.25,
32.67, 31.06, 19.38, 12.98, contains one equivalent of EtOAc.
High-resolution mass spectrometry: calc. 521.18885, found 521.19016.
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