Optimization of 8-Hydroxyquinolines as Inhibitors of Catechol O-Methyltransferase

Article abstract of DOI:10.1021/acs.jmedchem.8b01126

A series of 8-hydroxy quinolines were identified as potent inhibitors of catechol O-methyltransferase (COMT) with selectivity for the membrane-bound form of the enzyme. Small substituents at the 7-position of the quinoline were found to increase metabolic stability without sacrificing potency. Compounds with good pharmacokinetics and brain penetration were identified and demonstrated in vivo modulation of dopamine metabolites in the brain. An X-ray cocrystal structure of compound 21 in the S-COMT active site shows chelation of the active site magnesium similar to catechol-based inhibitors. These compounds should prove useful for treatment of many neurological and psychiatric conditions associated with compromised cortical dopamine signaling.

Full text of DOI:10.1021/acs.jmedchem.8b01126

Subscriber access provided by Iowa State University | Library
Article
Optimization of 8-Hydroxyquinolines as
Inhibitors of Catechol O-Methyltransferase
Ingrid Buchler, Daniel Akuma, Vinh Q. Au, Gregory Carr, Pablo de León, Michael DePasquale, Glen Ernst,
Yifang Huang, Martha Kimos, Anna Kolobova, Michael S Poslusney, Huijun Wei, Dominique Swinnen, Florian
Montel, Florence Moureau, Emilie Jigorel, Monika-Sarah Schulze, Martyn Wood, and James C Barrow
J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jmedchem.8b01126 • Publication Date (Web): 01 Oct 2018
Downloaded from http://pubs.acs.org on October 1, 2018
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
Optimization of 8ꢀHydroxyquinolines as Inhibitors of Catechol OꢀMethyltransferase
§
§
§
§,¶
§
Ingrid Buchler, Daniel Akuma, Vinh Au, Gregory Carr, Pablo de León, Michael
§
§
§
§
§
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
DePasquale, Glen Ernst, Yifang Huang, Martha Kimos, Anna Kolobova, Michael
§
§,¶
†
†
†
Poslusney, Huijun Wei, Dominique Swinnen, Florian Montel, Florence Moureau, Emilie
†
║
†
§,¶, *
Jigorel, MonikaꢀSarah E.D. Schulze, Martyn Wood, and James C. Barrow
§
Lieber Institute for Brain Development, 855 North Wolfe Street, Baltimore, MD 21205
Department of Pharmacology, Johns Hopkins University School of Medicine, 855 North Wolfe
¶
Street, Baltimore, MD 21287
†
UCB Biopharma SPRL, Bꢀ1420 Braineꢀl’Alleud, Belgium
║
UCB Biopharma, 216 Bath Road, Slough SL1 3WE, United Kingdom
ABSTRACT A series of 8ꢀhydroxy quinolines were identified as potent inhibitors of catechol
Oꢀmethyltransferase (COMT) with selectivity for the membraneꢀbound form of the enzyme.
Small substituents at the 7ꢀposition of the quinoline were found to increase metabolic stability
without sacrificing potency. Compounds with good pharmacokinetics and brain penetration
were identified and demonstrated in vivo modulation of dopamine metabolites in the brain. An
Xꢀray coꢀcrystal structure of compound 21 in the SꢀCOMT active site shows chelation of the
active site magnesium similar to catecholꢀbased inhibitors. These compounds should prove
useful for treatment of many neurological and psychiatric conditions associated with
compromised cortical dopamine signaling.
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 2 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
INTRODUCTION
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Proper functioning of dopamine signaling in the prefrontal cortex (PFC) is critical for a number
of cognitive and behavioral processes that are impaired in a variety of conditions such as ADHD,
1
obsessiveꢀcompulsive disorder, traumatic brain injury, and schizophrenia. One approach
towards selective modulation of dopamine signaling in the PFC is by inhibition of catechol Oꢀ
methyltransferase (COMT), which is the predominant means of dopamine clearance in the PFC
2
because of the lack of expression of synaptic dopamine transporters in this region, in contrast to
the striatum.
COMT is a magnesiumꢀcontaining metalloenzyme that transfers a methyl group from the
cofactor Sꢀadenosylmethionine (SAM) to a number of endogenous and exogenous catechols such
as dopamine, catecholestrogens, and dietary polyphenols. The COMT enzyme has two isoforms,
3
designated SꢀCOMT for the soluble form and MBꢀCOMT for the membraneꢀbound form. The
enzymatic domains of the two forms are identical, with MBꢀCOMT having an extra 50 amino
4
acids at the Nꢀterminus for membrane anchoring that also influences enzymatic activity. The
expression patterns of the two forms are different, with SꢀCOMT predominating in the periphery
and MBꢀCOMT being more prevalent in the brain, although this differential expression is
5
6
especially pronounced in humans compared to rodents. Since the goal is to achieve central
COMT inhibition, identification of a compound with MBꢀCOMT selectivity may be theoretically
desirable.
ACS Paragon Plus Environment

Page 3 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
Inhibitors of COMT are widely used for treatment of Parkinson’s disease due to their role in
inhibiting peripheral metabolism and thereby increasing levels of exogenously administered Lꢀ
7
DOPA. Notably, the nitrocatechol scaffold has been exploited to provide the clinically used
8
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
drugs tolcapone 1 and entacapone 2, as well as the recently approved opicapone 3 (Figure 1).
While they are effective in blocking peripheral COMT activity, entacapone and opicapone have
9
negligible brain penetration, and tolcapone has low but measurable levels in the brain.
Compounds with improved brain penetration have greater efficacy for the nonꢀmotor symptoms
10
of Parkinson’s disease, as well as have utility for other psychiatric and neurological conditions
1
1
such as cognitive impairment in schizophrenia. Despite the early clinical success achieved
1
2
with tolcapone, the drug has been associated with hepatic toxicity. Thus, the riskꢀbenefit
profile for tolcapone prevents its widespread deployment and new inhibitors of COMT are
needed, especially those that are active in the brain as well as those derived from alternate
pharmacophores to deꢀrisk any toxicity arising from the nitroꢀcatechol moiety.
Figure 1. Clinically used COMT inhibitors
1
3
Soon after the discovery of COMT by Julius Axelrod in 1957, Ross and Haljasmaa investigated
a number of compounds for their effects on COMT inhibition and identified 8ꢀhydroxyquinoline
1
4
(
4, Figure 2) as a nonꢀcatecholꢀcontaining inhibitor. Later, Borchardt and colleagues further
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 4 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
15
explored this template with modest success, but the field subsequently shifted focus to
nitrocatechols given the exquisite potency and high ligand efficiency of the nitrocatechol
7
, 16
pharmacophore.
While 3 was able to overcome the rapid metabolic clearance associated with
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
tolcapone by taking advantage of a slow off rate that extends the pharmacodynamic action
17
beyond its short plasma halfꢀlife, nitrocatechols generally suffer from poor pharmacokinetics
and limited brain penetration. Herein, we describe further exploration of the 8ꢀhydroxyquinoline
template and the discovery of potent inhibitors with excellent pharmacokinetics and brain
penetration.
RESULTS AND DISCUSSION
Borchardt’s exploration of 5ꢀsubstituted 8ꢀhydroxyquinolines showed that sulfonic acid
(compound 5, Figure 2) had similar COMT inhibition to other electron withdrawing groups
1
5
including chloro and nitro. In designing additional binding interactions for the 8ꢀ
hydroxyquinoline 4 (Figure 2) outside the metal chelating motif, modeling suggested substituents
on either the 5 or 6ꢀposition would overlay with nitrocatechol pharmacophore 1 (Figure 2). We
prepared both sulfone isomers 6 and 7 to guide future trajectories for exploration. While the 6ꢀ
substituted compound had a modest potency increase, the 5ꢀposition analog 7 appeared more
promising with an in vitro MBꢀCOMT pIC of 7.7.
5
0
ACS Paragon Plus Environment

Page 5 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 2. Evolution of the 8ꢀhydroxyquinoline lead. pIC values are reported for Human MBꢀ
5
0
COMT enzyme.
As shown in Table 1, a series of functional groups were appended at the 5ꢀposition, with sulfones
and 11 as well as sulfonamides 12 and 13 being preferable to ketone 9, amide 10, or direct
7
aromatics like 8. Additional sulfones and sulfonamides of varying sizes and polarity were
prepared such as 13; however, no meaningful increases in potency were achieved. A free
hydroxyl is required for optimum hydrogenꢀbonding and magnesium coordination in the COMT
active site, as compound 14 exhibited no appreciable inhibition of MBꢀCOMT. Poor metabolic
stability in rat hepatocytes was observed for representative compounds 12 and 13, and the 8ꢀ
hydroxyl moiety was suspected for phase II metabolism. Therefore, a series of sulfone and
sulfonamide analogs were prepared that investigated substituents at the 7ꢀposition to explore
steric and electronic effects on potency and metabolic stability.
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 6 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Table 1. Potency and Hepatocyte Clearance of 5ꢀsubstituted 8ꢀ
hydroxyquinolines
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
#
R
H
a
Hepatocyte Clearance
Human MBꢀCOMT pIC
b
6
5
0
(ꢁL/min/10 cells)
4
5.8±0.1
6.6±0.1
8
9
5.4±0.1
<5
1
0
7
7.7±0.1
8.2±0.1
8.1±0.3
1
1
2
1
1
177
255
3
4
8.5±0.2
1
<5
a
TM
Potency determined by MTase Glo
Methyltransferase assay from
membrane homogenate of recombinant human MBꢀCOMT overexpressed
b
in HEK cells. Hepatocyte clearance in rat hepatocytes.
Expanding the SAR around 5ꢀsubstituted sulfone and sulfonamide quinolines provided many
potent and brain penetrant examples as described in Table 2. Both aryl and alkyl substitution
were tolerated, as well as extension into larger and more diverse chemical space (data not shown,
ACS Paragon Plus Environment

Page 7 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
18
see patent application WO2016123576 for additional examples). However, building larger and
more expansive sulfone and sulfonamides decreased ligand efficiency, increased lipophilicity
and diminished physicochemical properties thereby leaving small substituents with the best
combination of potency and physiochemical properties. The clearance profile of both
sulfonamides and sulfones is driven by phase II metabolism of the 8ꢀhydroxy group; therefore,
screening in hepatocytes was used to capture the impact of metabolism in vitro. Poor metabolic
stability was observed with 7ꢀunsubstituted 8ꢀhydroxyquinolines as evident by the high
hepatocyte clearance for 15, 16, and 17 (Table 3). A tight correlation between rat hepatocytes
and in vivo clearance measured by PK studies was not evident; however, the hepatocyte screen
proved useful for triaging compounds with high clearance.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 8 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
a
Table 2. Enzyme Potency of 5,7ꢀsubstituted 8ꢀhydroxyquinolines
Human MBꢀ
Human Sꢀ
COMT pIC50
Rat MBꢀ
COMT pIC50
Rat SꢀCOMT
#
a
COMT pIC
pIC50
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
50
15
H
H
7
8
.3±0.3
.7±0.4
5.8±0.4
5.7±0.2
1
6
17
H
7
7
.2±0.1
.1±0.1
5.9±0.5
5.2±0.2
<5
1
1
2
8
9
0
F
Cl
F
6
.7±0.03
.4±0.7
8
5.8±0.1
>9
< 5
7
2
2
2
2
1
2
2
H
F
Cl
Br
7.7±0.1
8.2±0.3
6.5±0.2
5.9±0.4
<5
8.2±0.1
8.7±0.3
7.7±0.5
<5
6.3±0.4
6.3±0.4
<5
<5
<5
6.3±0.4
5.6±0.03
5.1±0.1
<5
1
2
3
4 CF
3
1
5
6
H
F
Cl
>9
>9
5.1
< 5
27 CF
3
12
28
H
F
Cl
8.1±0.3
8.4±0.6
8.0±0.2
7.7±0.3
5.7±0.1
5.8±0.4
5.5±0.1
5.5±0.4
>9
5.4
2
9
0
3
Me
a
TM
Potency determined by MTase Glo Methyltransferase assay from recombinant human
or rat MB and SꢀCOMT and are the average of three determinations.
Improvements in pharmacokinetic properties were observed when installing small groups at the
7
ꢀposition of the quinoline, presumably by affecting the phase II metabolism of the 8ꢀhydroxy
moiety. Substituents to modulate the susceptibility of hydroxyl metabolism with respect to both
steric and electronic effects were explored. As shown in Table 3, halogens generally showed
improved in vitro and in vivo clearance while larger, more sterically bulky groups reduced MBꢀ
COMT potency (e.g. compound 23). Strikingly, a CF substituent at the 7ꢀposition (compound
3
2
4) abolished MBꢀCOMT inhibition. A small methyl substituent was tolerated (compound 30)
but proved to have no impact on clearance as measured by rat hepatocytes. Both fluoro and
ACS Paragon Plus Environment

Page 9 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
chloro substitution yielded the best profiles with respect to metabolic stability, especially 7ꢀ
chloro substituted compounds 19, 26 and 29 which exhibited very low clearance and long halfꢀ
life in rat PK studies (Table 3).
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Table 3. ADME and Pharmacokinetic properties of 5,7ꢀsubstituted 8ꢀ
hydroxyquinolines
b
Rat PK
Hepatocyte Stability
%F
24
T1/2 (h)
0.18
Clp
(ml/min/kg)
V (L/kg)
ss
Example
(Rat)
6
(ꢁL/min/10 cells)
1
1
1
1
17
18
19
20
2
2
2
2
2
2
3
1
2
5
6
26
1.8
177
39
228
46
12
4
15
36
78
19
18
21
14
103
66
23
100
34
45
32
37
73
33
3.5
8.9
4.5
0.26
0.31
7.7
11
13
0.31
12
27
25
0.62
0.3
11
3.8
0.23
3.5
1
2
5
6
8
9
0
1.2
0.67
0.41
0.3
2.2
0.8
2.8
8.6
1
b
Rat pharmacokinetics after a 1mpk iv dose (n=3) and 3 or 10 mpk oral dose (n=3)
Brain penetration was initially assessed in mice by measuring total brain and plasma levels 5
minutes, 15 minutes, and 1 hour after an intraperitoneal (ip) 10 mg/kg dose in two mice at each
timepoint (Supplementary Table 1 for all timepoints and Table 4 for the 1 hour timepoint). Brain
penetration was generally rapid, so the 1 hour timepoint was chosen for compound comparison
in Table 4. Additionally, free fraction in plasma and brain were measured by equilibrium
dialysis. Early examples such as 15 and 16, where hydrogen is in the 7ꢀposition exhibited low
overall exposure consistent with poor pharmacokinetics. Compounds with either a 7ꢀfluoro or
chloro in both sulfone and sulfonamide moieties display good total plasma concentrations but
modest brain exposures relative to total plasma. However, most examples in Table 2 have
plasma protein binding approaching or greater than 99%, thereby limiting free drug
concentrations. Additionally, the examples in Table 4 exhibited higher free fraction in rat brain
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 10 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
tissue as compared to plasma which has the expected effect of driving down total brain
1
9
concentrations. Despite the protein/tissue binding differences, when correcting for free drug in
both compartments most compounds had reasonable ratios of unbound plasma and unbound
brain concentrations. The lower free brain drug concentrations relative to unpound plasma
concentrations observed for compounds such as 20 and 22 are outliers to the trend and could not
be explained by Pꢀgp efflux as these compounds were not substrates for the transporter (Table 4)
and have good apparent permeability (>100 nm/s, data not shown). Despite these two outliers,
overall the observations described in Tables 4 and 5 reinforce the notion that optimization of the
fraction unbound in the brain does not result in greater brain exposure, rather plasma free
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
9
fraction is more correlative to drug levels in brain.
Table 4. Mouse Brain Exposure of 5,7ꢀsubstituted 8ꢀ
hydroxyquinolines at one hour
d
Mouse Brain Penetration
Example
Pꢀgp
ER
Plasma
Protein
Binding
0.5 (r)
3.3 (m)
6.9 (m)
Brain
Tissue
Binding
2.9
4.4
10.3
a
Total Brain
(ng/g)
blq
Total Plasma
(ng/ml)
173
b
c
1
1
1
1
1
2
5
6
NT
NT
NT
NT
10.5
68
11
250
0.5 (m)
0.5
109
235
1
1
7
8
NT
1.1
1.4 (m)
0.6 (r)
NT
3.6
BLQ
1094
3538
2542
1
2
2
2
2
2
28
29
3
9
0
1
2
5
6
0.8
0.5 (r)
1.2 (r)
1.2 (r)
0.84 (m)
0.2 (r)
0.5 (r)
0.6 (r)
0.5 (r)
0.5 (m)
2.6
5655
527
518
1686
1914
2792
110
1154
55
16650
0.7
NT
1.1
0.5
NT
1.2
0.4
NT
2.4
1.39
0.5
4.2
1.6
8
5720
1744
9780
6160
14669
1819
16250
576
3.4
1.8
0
a
A:B/B:A efflux ratio from Pꢀglycoprotein expressing MDCK cells. NT=not
b
tested. Percent free from either mouse (m) or rat (r) plasma as measured by
equilibrium dialysis. Percent free from rat brain tissue. Total brain and total
plasma concentrations 1 hour after ip dosing 10mg/kg to 2 mice.
c
d
Central nervous system inhibition of COMT produces measurable changes in dopamine
metabolites dihydroxyphenyl acetic acid (DOPAC, increase) and homovanillic acid (HVA,
ACS Paragon Plus Environment

Page 11 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
decrease). Assessment of these biomarkers of dopamine metabolism in rat CSF with
accompanying measurement of inhibitor concentrations in plasma, brain homogenate, and CSF
provides a rapid readout for compound brain penetration and activity. While the region of
interest is the cortex, it has been demonstrated that CSF concentrations of HVA and DOPAC are
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
20
21
reflective of total brain levels and responsive to brainꢀpenetrant COMT inhibitors.
Table 5 shows the results from a single oral administration (10 mpk) of COMT inhibitors to rats
n=5ꢀ10, see Supplementary Table S2 for details). The animals were sacrificed 4 hours post dose
(
where plasma, brain, and CSF were analyzed for dopamine metabolites and drug levels. Values
for plasma protein binding and brain tissue binding (Table 4) were used to determine free plasma
and brain levels. Changes in HVA and DOPAC in CSF as measured by LCꢀMS are shown as a
difference between compound treated and vehicle treated controls. The positive control,
tolcapone (15 mpk, ip injection), exhibited expected biomarker movement where DOPAC was
increased and HVA decreased relative to control. Robust increases in DOPAC were observed
for all five compounds tested. More modest decreases were observed for HVA, with only 25 and
2
8 showing a statistically significant difference compared to the vehicle treated group.
Table 5. Effects of COMT inhibitors on rat biomarkers of dopamine metabolism
Example Free
Plasma
Free
Brain
Free CSF CSF
CSF/ Free CSF/ Free
Free CSF/
HVA DOPAC
b
c
c
(nM)
(nM) Plasma
Brain Ratio Free Plasma (%)
Ratio
N/A
16
(%)
a
a
(nM)
(nM)
BLQ
7.7
12.8
5.6
Ratio
N/A
2.6
1
2
2
2
35
48
19
32
23
NA
59
139
NA
77
BLQ
127
321
358
157
N/A
1.2
7.3
N/A
3.3
28
86
66
97
72
304
173
218
213
140
0
5
6
16.5
11
25
64
28
35
6.8
4.4
a
Free plasma and brain levels calculated using ratios listed in Table 4 on plasma and brain samples taken
b
immediately after CSF sampling. Total concentrations are given in Supplementary Table 2. Nonꢀspecific binding
to CSF was determined by equilibrium dialysis using pooled rat CSF as described in reference 24. Compound 20
c
showed 53% binding, Compound 25 showed 57% binding, and Compound 28 showed 51% binding.
HVA and
DOPAC changes (% of vehicle) 4 hours after 10mg/kg oral dose compared to vehicle (n=5ꢀ10 rats per group),
except 1 (15mpk ip). BLQ=Below the limit of quantitation.
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 12 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
All four quinoline analogs produced good peripheral exposure and brain levels as predicted from
the mouse brain penetration studies. Measurable drug concentrations for all compounds in brain
homogenate extracts exceeded rat MBꢀCOMT IC measurements; however, this series has less
5
0
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
activity on SꢀCOMT which may contribute to the modest changes in HVA relative to tolcapone.
Further studies with these compounds are in progress to obtain a more comprehensive
understanding of the effects of COMT inhibition by different classes of inhibitors. An
interesting additional observation is the lack of correlation between measured CSF levels and
calculated free plasma and free brain levels, which are expected to be similar for highly
permeable compounds that are not transporter substrates since the CSF has very low amounts of
2
2
protein compared to plasma. In addition to Pꢀgp (Table 4), compound 28 was also examined
for susceptibility to BCRP and MRP2 transporters, as well as for inhibitory activity against Pꢀgp,
BCRP, and MRP2. While compound 28 was not found to be a substrate or an inhibitor for these
three transporters (data not shown), that does not rule out susceptibility to other transporters
2
3
involved in bloodꢀbrainꢀCSF homeostasis. This prompted measurement of free CSF
24
concentrations using equilibrium dialysis. Compounds 20, 25, and 28 showed remarkably high
bound concentrations (51ꢀ57% bound @ 2 ꢁM testing concentration) in rat CSF suggesting that
2
5
even though proteins like albumin are in CSF at less than 1% compared to plasma, there exists
sufficient nonꢀspecific binding in CSF to effect the distribution of highly bound compounds.
Confirmation of the proposed binding mode of the 8ꢀhydroxyquinolines was confirmed by an Xꢀ
ray coꢀcrystal structure with 21 and SAM in the rat SꢀCOMT active site (Figure 3). As expected,
the hydroxyl and quinoline nitrogen make a bidentate interaction with the catalytic magnesium.
A free hydroxyl was observed to be required from the SAR studies (see Table 1, compound 14),
ACS Paragon Plus Environment

Page 13 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
and the structure reveals a tight hydrogenꢀbonding network around the hydroxyl similar to what
2
6
is seen with nitrocatechols. The sulfone oxygens make no clear contacts with the protein, but
orient the aromatic ring between tryptophanꢀ38 and tryptophanꢀ143 and over the thioether
sidechain of methionineꢀ40. The MB and S isoforms of COMT are identical except for an
additional 50 amino acids at the Nꢀterminus of MBꢀCOMT that are responsible for membrane
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
2
7
anchoring. Without a structure of compound 21 bound to MBꢀCOMT for comparison, it is
difficult to rationalize the selectivity for MBꢀCOMT over SꢀCOMT in this series, but it has been
proposed that residues 27ꢀ50 of MBꢀCOMT lay back over the active site to provide additional
2
8
binding interactions. The close proximity of the leucineꢀ198 sidechain to the quinoline 7ꢀ
position explains the tolerance for only small substituents at the 7ꢀposition. As judged by the
potency differences seen in Table 1 between sulfone 7 and sulfonamide 12 versus ketone 9 and
amide 10, other effects of the 5ꢀsubstituent may be at play since those substituents should also be
able to “fit” in similar binding modes albeit at a torsional cost. Also notable is that there is no
electron density for the transferable methyl group of SAM, and the structure is modeled with
SAH despite high purity SAM used in the crystallization conditions.
Figure 3. Compound 21 (magenta) bound to the rat SꢀCOMT active site (PDB 6GY1). The
hydroxyl and quinoline nitrogen make a bidentate interaction with the catalytic magnesium ion
(green sphere). The sulfone oxygens make no clear contacts with the protein, but orient the
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 14 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
aromatic ring between trytophanꢀ38 and tryptophanꢀ143 and over the thioether sidechain of
methionineꢀ40.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
CHEMISTRY
Scheme 1 shows the preparation of unsubstituted and nonꢀfluoro sulfonamides 12, 13 and 16,
beginning with chlorosulfonylation of 8ꢀfluoroquinoline 31 followed by treatment of the desired
amine and quenching with sodium 2ꢀ(trimethylsilyl)ethanꢀ1olate to displace the labile 8ꢀfluoro
group to give 33. Removal of the TMSE protecting group followed by treatment with Nꢀchloro
succinimide (NCS) gave the desired sulfonamide 29. The corresponding sulfones 7 and 23 were
prepared according to Scheme 2 by PMB protection of 5ꢀiodoꢀ8ꢀhydroxyquinoline 35 followed
29
by copper (I) mediated coupling with 4ꢀmethylbenzenesulfinate to install the sulfone group.
The protecting group was removed with TFA at ambient temperature to provide compound 7.
Bromination of 7 was achieved with NBS in chloroform to give example 23. Additional 7ꢀ
chloro sulfone analogs were prepared by chlorination with NCS followed by benzylating 5ꢀ
bromoꢀ8ꢀhydroxyquinoline 36 (Scheme 3). Palladium catalyzed cross coupling of thiols
3
0
produced thioethers 35. The desired thioethers could be prepared in either one step
(compounds 22 and 26) or by use of an intermediary TMSꢀthioethane (example 19). Oxidation
of the sulfur with mCPBA gave sulfones with minimal quinoline Nꢀoxide formation. Acidꢀ
catalyzed deprotection of the benzyl group provided the desired analogs 39. Incorporation of a
fluorine at the 7ꢀposition of the quinoline was accomplished as described in Scheme 4. A Skraup
31
reaction was used to prepare the 7ꢀfluoroꢀ8ꢀhydroxyquinoline 41 which could be either
chlorosulfonylated and quenched with amines to give sulfonamide 28, or iodinated and protected
to give key intermediate 42. Palladium catalyzed coupling of thiols followed by oxidation and
ACS Paragon Plus Environment

Page 15 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
deprotection gave the desired sulfones 44. Other quinolines shown in Table 1 could be prepared
as shown in Scheme 5, via direct FriedelꢀCrafts acylation to give ketone 9, or introduction of the
8ꢀhydroxyl as a protected benzyl by SnAr on 8ꢀfluoroquinolines 46 or 48 which led to
compounds 10 and 6 respectively.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 1. General synthetic prcedures for sulfonamides 12, 13, 16, 29. Reagents and
conditions: (a) chlorosulfonic acid, 100 °C, 71%; (b) DIPEA, amine, THF then NaH, 2ꢀ
0
(trimethylsilyl)ethanol; (c) CsF, DMF, 60 °C, 84% or TBAF, THF, 34%; (d) NCS, CHCl 60 C,
3
,
2
4%.
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 16 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 2. Synthetic protocol for 7 and 23. Reagents and conditions: (a) K CO , PMBꢀCl,
2
3
ACN, 22%; (b) CuI, DMSO, 4ꢀmethylbenzenesulfinate, 90 °C, 22%; (c) TFA, rt, 92%; (d) NBS,
CHCl , 85%.
3
Scheme 3. General synthetic procedures for 19, 22, and 26. Reagents and conditions: (a) NCS,
CHCl , 78%; (b) K CO , BnBr, ACN, 89%; (c) 2ꢀtrimethylsilylethanethiol (example 19) or
3
2
3
R SH (examples 22 and 26), Xantphos, Cs CO , Pd (dba) , dioxane, 100 °C, 93% example 19;
1
2
3
2
3
ACS Paragon Plus Environment

Page 17 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
8
1% example 22, 93% example 26; (d) for example 19, 4ꢀfluoroiodobenzene, TBAF, Xantphos,
Cs CO , Pd (dba) , dioxane, 90 °C, 93%; (e) mCPBA, DCM; (f) 6M aqueous HCl, 100 °C.
2
3
2
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 4. General synthetic protocol for 18, 20, 21, 25, and 28. Reagents and conditions: (a)
glycerol, sodiumꢀ3ꢀnitrobenzenesulfonate, 70% sulfuric acid, 140 °C, 56%; (b) chlorosulfonic
acid, CHCl3, 100 °C, 40%; (c) triethylamine, pyrrolidine, DCM, 0 °C, 98%; (d) NIS, CHCl , 40
3
°
C, 92%; (e) NaH, BnBr, DMF, 73%; (f) thiol, Xantphos, Cs CO , Pd (dba) , dioxane, 90 °C; (g)
2 3 2 3
mCPBA, DCM; (h) 6M aqueous HCl, 100 °C.
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 18 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 5. Synthetic protocols for ketone 9, amide 10, and sulfone 6. a) AlCl , 4ꢀ
3
methylbenzoyl chloride, toluene, 110 °C, 5%; b) NaH, BnOH, THF; c) NaOH, THF/H O, 63%;
2
d) 1ꢀChloroꢀN,N,2ꢀtrimethylꢀ1ꢀpropenylamine, DCM then pyrrolidine; e) HBr, acetic acid, 63%
over 2 steps; f) Cu(I)I, K CO , DMEN, DMSO, sodium 4ꢀmethylbenzenesulfinate,46%; g) 6M
2
3
HCl,87%.
CONCLUSIONS
A series of 8ꢀhydroxyquinolines were prepared and evaluated as COMT inhibitors, and several
potent MBꢀCOMT inhibitors were identified that demonstrate selectivity over SꢀCOMT. An Xꢀ
ray coꢀcrystal structure highlights the important chelation of the active site magnesium; however,
the interactions responsible for the observed MBꢀCOMT selectivity are not apparent in the Sꢀ
ACS Paragon Plus Environment

Page 19 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
COMT structure. Small substituents at the 7ꢀposition were found to increase metabolic stability
without sacrificing potency, and compounds with good pharmacokinetics such as 25 and 28 were
identified. This series of compounds generally has good brain penetration, although high plasma
protein binding results in high exposures required for efficacy in a rat biomarker assay of COMT
activity. Further in vivo characterization of these compounds on central nervous system
dopamine metabolism will be reported in due course.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
EXPERIMENTAL SECTION
General Procedures. All commercially available reagents and solvents were used without
further purification unless otherwise stated. Automated flash chromatography was performed on
TM
TM
an ISCO CombiFlash Rf or Biotage Isolera using Biotage Flash cartridges with peak
detection at 254 nm. Reverse phase purification was accomplished using a Gilson 215 liquid
handler equipped with a Phenomenex C18 column (150 x 20 mm I.D., Sꢀ5 ꢁm). Peak collection
1
was triggered by UV detection at 214 or 254 nm. H NMR spectra were recorded on a Bruker
4
00 instrument operating at 400 MHz with tetramethylsilane or residual protonated solvent used
as a reference. Analytical LCꢀMS was performed using Agilent 1260 equipped with autosampler
Agilent Poroshell 120 C18 column (50 x 3.0 mm I.D., 2.7 ꢁm); 0.05% TFA in water/acetonitrile
(
gradient; UV detection at 215 and 254 nm) and electrospray ionization. All final compounds
showed purity greater than 95% at 215 and 254 nm using this method.
6
ꢀTosylquinolinꢀ8ꢀol (6). Step 1. To a solution of benzyl alcohol (1.1 mL, 10.8 mmol)
in THF (30 mL) was added sodium hydride (0.44 g, 10.8 mmol) portionwise over 5 min. The
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 20 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
resulting mixture was allowed to stir for 30 min, then a solution of 6ꢀbromoꢀ8ꢀfluoroꢀquinoline
4
7 (1.6 g, 7.2 mmol) in THF (15 mL) was added dropwise over 5 min. The contents were stirred
at room temperature for 4 days (for convenience). The reaction mixture (which had become
gelatinous) was taken up in EtOAc and washed with water (4 X), brine (1 X), dried over MgSO4,
filtered, and the solvent removed in vacuo. The desired product crystallised upon standing and
was washed with ethyl acetate then airꢀdried to give 0.53 g of pure desired product. The filtrate
was concentrated and purified by automated normalꢀphase chromatography (0ꢀ40%
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
EtOAc/hexanes, 50 g silica gel cartridge). The productꢀcontaining fractions were combined and
the solvent removed in vacuo to give a white solid, which when combined with the crystallized
material to provide a total of 8ꢀbenzyloxyꢀ6ꢀbromoꢀquinoline 48 (1.3 g, 57% yield) as a white
1
solid. H NMR (400 MHz, DMSOꢀd ) δ ppm 8.88 (dd, J = 4.04, 1.77 Hz, 1 H) 8.31 (dd, J =
6
8
.34, 1.77 Hz, 1 H) 7.83 (d, J = 2.02 Hz, 1 H) 7.60 (dd, J = 8.34, 4.04 Hz, 1 H) 7.53 ꢀ 7.57 (m, 2
+
H) 7.42 ꢀ 7.47 (m, 3 H) 7.35 ꢀ 7.41 (m, 1 H) 5.34 (s, 2 H). MS (ES+) m/z 314.0 [M+H] .
Step 2. A mixture of copper (I) iodide (28 mg, 0.15 mmol), 8ꢀbenzyloxyꢀ6ꢀbromoꢀ
quinoline 48 (100 mg, 0.32 mmol), sodium 4ꢀmethylbenzenesulfinate (170 mg, 0.95 mmol) and
potassium carbonate (88 mg, 0.64 mmol) and N,N'ꢀdimethylethylenediamine (6.8 µL, 0.06
o
mmol) in DMSO (3 mL) was heated to 90 C for 60 min under microwave heating. The contents
were diluted with EtOAc, washed with water (3 X), brine, dried over MgSO , filtered and the
4
solvent removed in vacuo to give a yellow residue. This material was purified by automated
normalꢀphase chromatography (0ꢀ100% EtOAc/hexanes, 4 g silica gel cartridge). The productꢀ
containing fractions were combined and the solvent removed in vacuo to give 8ꢀbenzyloxyꢀ6ꢀ(pꢀ
1
tolylsulfonyl)quinoline 49 (57 mg, 46% yield) as a beige solid. H NMR (400 MHz, CDCl ) δ
3
ppm 9.07 (dd, J = 4.17, 1.64 Hz, 1 H) 8.22 ꢀ 8.27 (m, 1 H) 8.07 (d, J = 1.77 Hz, 1 H) 7.66 ꢀ 7.71
ACS Paragon Plus Environment

Page 21 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
(
m, 2 H) 7.53 ꢀ 7.58 (m, 1 H) 7.47 ꢀ 7.52 (m, 2 H) 7.41 (d, J = 2.02 Hz, 1 H) 7.31 ꢀ 7.39 (m, 3 H)
+
7
.22 (d, J = 8.08 Hz, 2 H) 5.48 (s, 2 H) 2.39 (s, 3 H). MS (ES+) m/z 390.0 [M+H] .
Step 3. 8ꢀbenzyloxyꢀ6ꢀ(pꢀtolylsulfonyl)quinoline 49 (55 mg, 0.14 mmol) and 6 M
o
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
hydrochloric acid (0.64 mL, 3.8 mmol) were stirred at 100 C for 4 h, then allowed to cool to
room temperature. The solid was collected by filtration, washed with water and dried under
1
vacuum to give 6ꢀ(pꢀtolylsulfonyl)quinolinꢀ8ꢀol 6 (36 mg, 87% yield) as a beige solid. H NMR
(400 MHz, DMSOꢀd ) δ ppm 9.05 (dd, J = 4.42, 1.64 Hz, 1 H) 8.75 (d, J = 8.34 Hz, 1 H) 8.24
6
(d, J = 2.02 Hz, 1 H) 7.88 (d, J = 8.34 Hz, 2 H) 7.81 (dd, J = 8.34, 4.29 Hz, 1 H) 7.45 (dd, J =
+
5
.05, 3.03 Hz, 3 H) 2.37 (s, 3 H). MS (ES+) m/z 300.0 [M+H] .
5
ꢀTosylquinolinꢀ8ꢀol (7). Step 1. To a stirring solution of 5ꢀiodoquinolinꢀ8ꢀol 34 (4.1 g,
1
5.3 mmol) in acetonitrile (100 mL) was added potassium carbonate (4.2 g, 30.8 mmol). The
suspension was stirred at room temperature for 30 minutes. 4ꢀMethoxybenzyl chloride (2.5 mL,
o
1
8.4 mmol) was added and the resultant suspension was heated at 80 C for 4 hours. After
cooling to room temperature, the suspension was filtered, the filter cake washed with ethyl
acetate and filtrate was concentrated to a residue. The residue was purified by automated
normalꢀphase chromatography and eluted with ethyl acetate/hexanes (0ꢀ80%) to give 8ꢀ((4ꢀ
1
methoxybenzyl)oxy)ꢀquinoline 50 as an offꢀwhite solid (1.4 g, 22 % yield). H NMR (400 MHz,
DMSOꢀd6) δ ppm 8.86 (dd, J = 4.04, 1.52 Hz, 1 H) 8.29 (dd, J = 8.46, 1.64 Hz, 1 H) 8.06 ꢀ8.11
(m, 1 H) 7.67 (dd, J = 8.59, 4.29 Hz, 1 H) 7.43 ꢀ 7.49 (m, 2 H) 7.15 (d, J = 8.34 Hz, 1 H) 6.95 ꢀ
+
7
.01 (m, 2 H). MS (ES+) m/z 392.0 [M+H] .
Step 2. To a stirring solution of 5ꢀiodoꢀ8ꢀ((4ꢀmethoxybenzyl)oxy)quinoline 50 (0.20 g,
0.51 mmol) in DMSO (1.5 mL), copper (I) iodide (10 mg, 0.051 mmol), sodium (S)ꢀpyrrolidineꢀ
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 22 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
2
ꢀcarboxylate (14 mg, 0.10 mmol) and sodium 4ꢀmethylbenzenesulfinate (109 mg, 0.61 mmol)
o
were added. The solution was heated at 90 C for 24 hrs. Water (2 mL) was added and precipitate
isolated by filtration. The crude material was purified by automated normalꢀphase
chromatography, using ethyl acetate/hexanes (0ꢀ80%) as an eluent to give 8ꢀ((4ꢀ
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
methoxybenzyl)oxy)ꢀ5ꢀtosylquinoline 35 as an offꢀwhite solid (47 mg, 22% yield). H NMR
(400 MHz, CDCl ) δ ppm 9.00 (s, 2 H) 8.42 (d, J = 8.34 Hz, 1 H) 7.81 (d, J = 8.34 Hz, 2 H)
3
7
.53 (dd, J = 8.84, 4.29 Hz, 1 H) 7.45 (d, J = 8.59 Hz, 2 H) 7.24 ꢀ 7.31 (m, 4 H) 7.16 (d, J =
8
.59 Hz, 1 H) 6.88 ꢀ 6.99 (m, 2 H) 5.45 (s, 2 H) 3.79 ꢀ 3.86 (m, 3 H). MS (ES+) m/z 420.0
+
[
M+H] .
Step 3. 8ꢀ((4ꢀMethoxybenzyl)oxy)ꢀ5ꢀtosylquinoline 35 (47 mg, 0.11 mmol) was
dissolved in TFA (0.86 mL, 11.2 mmol) and stirred at room temperature for 1 hour. The solution
was concentrated. The residue was purified by recrystallization in ethyl acetate/hexanes to give
1
5ꢀtosylquinolinꢀ8ꢀol 7 as an offꢀwhite solid (30 mg, 92% yield). H NMR (400 MHz, DMSOꢀ
d6) δ ppm 8.94 (dd, J = 4.17, 1.64 Hz, 1 H) 8.89 (dd, J = 8.72, 1.64 Hz, 1 H) 8.39 (d, J = 8.34
Hz, 1 H) 7.80 ꢀ 7.86 (m, 2H) 7.73 (dd, J = 8.72, 4.17 Hz, 1 H) 7.35 ꢀ 7.41 (m, 2 H) 7.27 (d, J =
+
8
.34 Hz, 1 H) 2.32 (s, 3 H). MS (ES+) m/z 300.0 [M+H] .
5
ꢀ(pꢀTolyl)quinolineꢀ8ꢀol (8). Step 1. To a solution of 5ꢀbromoquinolinꢀ8ꢀol 36
(5 g, 22.3 mmol) in DMF (40 mL) and THF (20 mL) was added sodium hydride (1.1 g, 26.7
mmol). After 15 minutes benzyl bromide (3.1 mL, 26.7 mmol) was added slowly dropwise. The
reaction was maintained at ambient temperature overnight. The reaction was quenched by
addition of water, solids formed and were collected by filtration to yield 7.3 g (assume
1
quantitative yield) of 8ꢀbenzyloxyꢀ5ꢀbromoꢀquinoline 51. H NMR (400 MHz, DMSOꢀd ) δ
6
ACS Paragon Plus Environment

Page 23 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
ppm 8.95 (br. s., 1 H) 8.47 (d, J = 8.08 Hz, 1 H) 7.88 (d, J = 8.34 Hz, 1 H) 7.73 (br. s., 1 H) 7.55
(br. s., 2 H) 7.41 (dd, J = 17.68, 6.82 Hz, 3 H) 7.28 (d, J = 8.08 Hz, 1 H) 5.34 (br. s., 2 H). MS
+
(ES+) m/z 314.0 [M+H] .
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Step 2. A vial was charged with 8ꢀbenzyloxyꢀ5ꢀbromoꢀquinoline 51 (150 mg, 0.48
mmol), Pd(PPh ) (55 mg, 0.05 mmol), 4ꢀmethylphenylboronic acid (77 mg, 0.57
3
4
mmol), NaHCO (0.48 mL, 0.95 mmol) 2M aqueous solution in 1,4ꢀdioxane (5 mL). The vial
3
o
was sparged with nitrogen for 5 minutes and heated at 90 C overnight. The reaction was
concentrated to a residue, resultant residue partitioned between water and ethyl acetate, layers
separated, aqueous extracted (2 X 2 mL), organics passed through a phase separator tube and
solution concentrated to an oil. Purification was accomplished by automated silica gel
chromatography (12 g preꢀpacked silica cartridge) eluting with 0ꢀ100% ethyl acetate/heptane to
1
provide 8ꢀbenzyloxyꢀ5ꢀ(pꢀtolyl)quinoline 52 as a yellow glass (150 mg, 97% yield). H NMR
(400 MHz, DMSOꢀd ) δ ppm 2.40 (s, 3 H) 5.36 (s, 2 H) 7.33 ꢀ 7.40 (m, 4 H) 7.40 ꢀ 7.48 (m, 4 H)
6
7
.51 ꢀ 7.61 (m, 4 H) 8.17 (dd, J=8.59, 1.52 Hz, 1 H) 8.89 (dd, J=4.04, 1.52 Hz, 1 H). MS (ES+)
+
m/z 326.0 [M+H] .
Step 3. A solution of 8ꢀbenzyloxyꢀ5ꢀ(pꢀtolyl)quinoline 52 (150 mg, 0.46 mmol)
dissolved in 1,4ꢀdioxane (2 mL) and 6N aqueous hydrochloric acid (3 mL, 18 mmol) was heated
o
at 100 C for 4 hours. The material was concentrated to a residue and purified by automated
1
reversed phase HPLC to yield 85 mg (52%) of 5ꢀ(pꢀtolyl)quinolineꢀ8ꢀol 8 as a TFA salt. H
NMR (400 MHz, DMSOꢀd ) δ ppm 2.40 (s, 3 H) 7.30 (d, J=8.08 Hz, 1 H) 7.33 ꢀ 7.37 (m, 4 H)
6
7
.51 (d, J=8.08 Hz, 1 H) 7.73 (dd, J=8.59, 4.55 Hz, 1 H) 8.48 (d, J=8.34 Hz, 1 H) 8.98 (dd,
+
J=4.55, 1.52 Hz, 1 H). MS (ES+) m/z 236.2 [M+H] .
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 24 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(
8ꢀHydroxyquinolinꢀ5ꢀyl)(pꢀtolyl)methanone (9). To a mixture of 8ꢀ
hydroxyquinoline 4 (250 mg, 1.7 mmol) dissolved in toluene (3 mL) was added 4ꢀmethylbenzoyl
o
chloride (0.23 mL, 1.7 mmol). The resultant solution was cooled to 0 C and aluminum chloride
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(
574 mg, 4.3 mmol) was added in 2 portions. The resultant mixture was allowed to warm to
ambient temperature for 2 hours. The material was quenched by pouring over ice and 1M HCl
aqueous solution. The acidic solution was extracted with ethyl acetate (2 X 10 mL). The organics
were combined, dried over sodium sulfate and concentrated to a residue. Purification was
accomplished by automated normalꢀphase chromatography using 0ꢀ5%
1
methanol/dichloromethane as an eluent to provide 24 mg (5% yield) of title compound 9. H
NMR (400 MHz, DMSOꢀd6) δ ppm 8.89 (br. s., 1 H) 8.53 (d, J = 7.83 Hz, 1 H) 8.11 (d, J = 8.08
Hz, 2 H) 7.99 (d, J = 6.82 Hz, 1 H) 7.68 ꢀ 7.76 (m, 2 H) 7.64 (d, J = 4.55 Hz, 1 H) 7.46 (d, J =
+
7
.58 Hz, 2 H) 2.45 (s, 3 H). MS (ES+) m/z 264.1 [M+H] .
(
8ꢀHydroxyquinolinꢀ5ꢀyl)(pyrrolidinꢀ1ꢀyl)methanone (10). Step 1. To a solution of
ethyl 8ꢀhydroxyquinoineꢀ5ꢀcarboxylate 45 (270 mg, 1.2 mmol) in dry DMF (10 mL) was added
sodium hydride (60 mg, 1.4 mmol) at ambient temperature. After 5 minutes benzyl bromide
(
0.18 mL, 1.4 mmol) was added in a dropwise manner. The reaction was allowed to stir at
ambient temperature. After 15 minutes the reaction was quenched by addition of iceꢀwater. The
aqueous mixture was extracted (2 X 20 mL) ethyl acetate, organic washes combined, dried over
sodium sulfate and concentrated to a residue. Purification was accomplished automated normalꢀ
phase chromatography (40 g silica gel cartridge) eluting 0ꢀ100% ethyl acetate/hexanes to provide
2
59 mg as a 1:1 mixture of ethylꢀ8ꢀbenzyloxyquinolineꢀ5ꢀcarboxylate 53 and 8ꢀ
ACS Paragon Plus Environment

Page 25 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
benzyloxyquinoline. The mixture was taken on in the next step without additional purification.
+
MS (ES+) m/z 308.0 [M+H] .
Step 2. To a solution of ethylꢀ8ꢀbenzyloxyquinolineꢀ5ꢀcarboxylate 53 mixture (250 mg,
o
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
0
.81 mmol) in THF (10 mL) was added water (10 mL). The mixture was allowed to stir at 40 C
overnight. The pH was adjusted to ~4ꢀ5 by addition of 4.5 M aqueous hydrochloric acid. Solids
formed and collected by filtration, washed with water and dried in a vacuum oven to yield 8ꢀ
1
benzyloxyquinolineꢀ5ꢀcarboxylate 46 (144 mg, 63% yield). H NMR (400 MHz, DMSOꢀd ) δ
6
ppm 12.99 (br. s., 1 H) 9.42 (dd, J = 8.84, 1.77 Hz, 1 H) 8.91 (dd, J = 4.04, 1.52 Hz, 1 H) 8.26 ꢀ
8
.31 (m, 1 H) 7.68 (dd, J = 8.59, 4.04 Hz, 1 H) 7.57 (d, J = 6.82 Hz, 2 H) 7.42 ꢀ 7.48 (m, 2 H)
+
7.34 ꢀ 7.41 (m, 2 H) 5.39 (s, 2 H). MS (ES+) m/z 280.0 [M+H] .
Step 3. To a slurry of 8ꢀbenzyloxyquinolineꢀ5ꢀcarboxylate 46 (61 mg, 0.22 mmol) in dry
dichloroethane (2 mL) was added Ghosez reagent (0.29 mL, 2.1 mmol) at ambient temperature.
To drive the reaction into solution additional Ghosez reagent was added (totaling 0.7 mL). After
1
hour, pyrrolidine (0.54 mL, 6.5 mmol) was added. The reaction was stirred at ambient
temperature for 1 hour then diluted with dichloromethane and extracted (1 X 3 mL) water. The
material was passed through a phase separator tube and organic layer concentrated to a residue.
Purification was accomplished by automated normalꢀphase chromatography using 0ꢀ10%
methanol/dichloromethane as an eluent. The oily (8ꢀbenzyloxyꢀ5ꢀquinolyl)ꢀpyrrolidinꢀ1ꢀylꢀ
methanone solidified upon standing (102 mg). The crude material was taken on without
additional purification and or characterization.
A mixture of (8ꢀbenzyloxyꢀ5ꢀquinolyl)ꢀpyrrolidinꢀ1ꢀylꢀmethanone (83 mg, 0.29 mmol)
dissolved in acetic acid (0.5 mL) was added hydrobromic acid (0.5 mL). The resultant mixture
o
was heated to 100 C for 3 hours. The material was cooled to ambient temperature and
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 26 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
neutralized with 6 M sodium hydroxide. The aqueous solution was extracted (3 X 2 mL)
dichloromethane, organics combined, filtered through a phase separator tube and concentrated to
a residue. Purification was accomplished by automated normalꢀphase chromatography using 0ꢀ
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
0% methanol/dichloromethane as an eluent. The impure material was concentrated to a residue
then purified by automated reversedꢀphase chromatography eluting 5ꢀ95% acetonitrile/water,
0
.05% trifluoroacetic acid as modifier. A yellow foam of 8ꢀhydroxyquinolinꢀ5ꢀyl)(pyrrolidinꢀ1ꢀ
1
yl)methanone 10 (57 mg, 43% yield) was obtained. H NMR (400 MHz, DMSOꢀd ) δ ppm 8.95
6
(dd, J = 4.17, 1.39 Hz, 1 H) 8.47 (d, J = 8.59 Hz, 1 H) 7.73 (dd, J = 8.34, 4.55 Hz, 1 H) 7.59 (d,
J = 8.08 Hz, 1 H) 7.17 (d, J = 8.08 Hz, 1 H) 3.58 (t, J = 6.82 Hz, 2 H) 3.16 (t, J = 6.44 Hz, 2 H)
+
1.86 ꢀ 1.97 (m, 2 H) 1.73 ꢀ 1.84 (m, 2 H). MS (ES+) m/z 243.0 [M+H] .
5
ꢀ(Cyclopentylsulfonyl)quinolineꢀ8ꢀol (11). Step 1. 8ꢀHydroxyquinolineꢀ5ꢀsulfonic
acid hydrate (10 g, 41.1 mmol) was dissolved in sodium hydroxide solution (1 N, 103 mL, 103
o
mmol) and heated to 75 C. A solution of benzyl chloride (10.4 ml, 90 mmol) in THF (100 mL)
o
was added and resultant mixture maintained at 75 C overnight. After cooling to room
o
temperature, the solution was extracted with diethyl ether twice, then placed chilled at 4 C for 4
hours. The solid was collected by filtration and dried to give 8ꢀbenzyloxyquinolineꢀ5ꢀsulfonic
1
acid 54 (6.3 g, 48% yield) a white solid. H NMR (400 MHz, DMSOꢀd ) δ ppm 9.10 ꢀ 9.17 (m,
6
1
H) 8.84 (dd, J = 4.2, 1.6 Hz, 1 H) 7.88 (d, J = 8.1 Hz, 1 H) 7.52 ꢀ 7.60 (m, 3 H) 7.39 ꢀ 7.46 (m,
+
2 H) 7.32 ꢀ 7.39 (m, 1 H) 7.20 (d, J = 8.1 Hz, 1 H) 5.32 (s, 2 H). MS (ES+) m/z 316.0 [M+H]
Step 2. To a stirring solution of 8ꢀbenzyloxyquinolineꢀ5ꢀsulfonic acid 54 (6.3 g, 20.0
mmol) and thionyl chloride (100 mL, 20.0 mmol) was added DMF (3 drops). The solution was
o
heated at 80 C for 3 hours. The solution was cooled to room temperature and concentrated.
ACS Paragon Plus Environment

Page 27 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
Toluene (50 ml) was added and the resultant mixture concentrated to azeotrope excess thionyl
chloride, and the resultant suspension was concentrated to give 8ꢀbenzyloxyquinolineꢀ5ꢀsulfonyl
1
chloride 55 (8.9 g) as a pale yellow solid. H NMR (400 MHz, CDCl ) δ ppm 5.76 (s, 2 H) 7.30
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
ꢀ
(
7.45 (m, 13 H) 7.62 ꢀ 7.70 (m, 6 H) 8.25 (dd, J = 8.84, 5.05 Hz, 3 H) 8.50 ꢀ 8.56 (m, 3 H) 9.59
+
dd, J = 5.05, 1.26 Hz, 3 H) 9.66 (dd, J = 8.84, 1.01 Hz, 3 H). MS (ES+) m/z 334.9 [M+H]
Step 3. To a stirring solution of 8ꢀbenzyloxyquinolineꢀ5ꢀsulfonyl chloride 55 (14 g, 41.9
mmol) in THF (100 mL) was added triphenylphosphine (33 g, 125.8 mmol). An exotherm was
o
observed and reaction mixture turned dark brown. The solution was heated at 60 C for 60
minutes then cooled to room temperature. Diethyl ether (50 ml) was added, a precipitate formed
and solids collected by filtration. After dissolving the precipitate in DMF, sodium borohydride
(2.0 g, 54.5 mmol) was added. The solution was stirred at room temperature for 30 minutes.
o
Cyclopentyl iodide (8.2 g, 41.9 mmol) was added and the reaction heated to 60 C for two hours.
The solution was cooled to room temperature and diluted with water (50 mL). The solution was
extracted with ethyl acetate (3 X 50 mL). The combined organic washes were extracted with
water (3 X 40 mL), brine (1 X 50 mL), dried over sodium sulfate, filtered and concentrated. The
residue was purified automated normalꢀphase chromatography and eluted with ethyl
acetate/hexane (0ꢀ50%) to give 8ꢀbenzyloxyꢀ5ꢀcyclopentylsulfanylꢀquinoline 56 (2.3 g, 16%
1
yield) as a colorless oil. H NMR (400 MHz, CDCl ) δ ppm 8.99 ꢀ 9.05 (m, 1 H) 8.86 (dd, J =
3
8
.5, 1.6 Hz, 1 H) 7.65 (d, J = 8.1 Hz, 1 H) 7.50 ꢀ 7.59 (m, 3 H) 7.29 ꢀ 7.43 (m, 3 H) 6.96 ꢀ 7.03
(m, 1 H) 5.44 ꢀ 5.50 (m, 2 H) 3.36 ꢀ 3.47 (m, 1 H) 1.73 ꢀ 1.94 (m, 4 H) 1.49 ꢀ 1.67 (m, 4 H). MS
+
(
ES+) m/z 336.1 [M+H] .
Step 4. To a stirring solution of 8ꢀbenzyloxyꢀ5ꢀcyclopentylsulfanylꢀquinoline 56 (5.3 g,
1
5.8 mmol) in DCM (150 mL), 3ꢀchlorobenzenecarboperoxoic acid (1.1 g, 4.7 mmol) was
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 28 of 77
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
added. The solution was stirred at room temperature for 30 minutes. Sodium sulfite solution (1
M, 30 mL) was added. The solution was extracted with sodium hydroxide solution (1.0 N, 2 X
60 mL), brine (1 X 60 mL) and dried over sodium sulfate. The solution was filtered and
concentrated. The residue was purified by automated normalꢀphase chromatography and eluted
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
with methanol/dichloromethane (0ꢀ4%) to give 8ꢀbenzyloxyꢀ5ꢀcyclopentylsulfonylꢀquinoline 57
1
(
3.7 g, 61% yield) as a white solid. H NMR (400 MHz, DMSOꢀd ) δ ppm 8.97 ꢀ 9.04 (m, 2 H)
6
8
.22 (d, J = 8.3 Hz, 1 H) 7.75 ꢀ 7.81 (m, 1 H) 7.55 ꢀ 7.62 (m, 2 H) 7.36 ꢀ 7.53 (m, 4 H) 5.42 (s, 2
+
H) 3.78 ꢀ 3.90 (m, 1 H) 1.47 ꢀ 1.95 (m, 8 H). MS (ES+) m/z 368.1 [M+H] .
Step 5. To a stirring solution of 8ꢀbenzyloxyꢀ5ꢀcyclopentylsulfonylꢀquinoline 57 (3.7 g,
10.1 mmol) in acetic acid (50 mL), hydrobromic acid (34 mL, 201.9 mmol) was added. The
o
solution was stirred at 100 C for 5 hours. The solution was cooled to room temperature and
concentrated to half of its volume. The solution was washed with diethyl ether and etheral wash
o
chilled at 4 C overnight. The white precipitate was collected by filtration and dried to give the
desired product as a hydrobromide salt. The solid was dissolved in aqueous sodium hydroxide
solution (0.5 N, 50 mL). The solution was filtered to remove particulates and then filtrate
adjusted to slightly acidic by adding hydrochloric acid solution (1 N, ~pH 5ꢀ6). The solution
was triturated with saturated sodium bicarbonate aqueous solution to provide a white
precipitate. The precipitate was isolated by filtration, washed with water three times, and airꢀ
1
dried to give 5ꢀcyclopentylsulfonylquinolinꢀ8ꢀol 11 (1.7 g, 61% yield) as a free base. H NMR
(400 MHz, DMSOꢀd ) δ ppm 11.17 (br. s., 1 H) 8.97 ꢀ 9.05 (m, 2 H) 8.13 (d, J = 8.3 Hz, 1 H)
6
7
.75 ꢀ 7.84 (m, 1 H) 7.24 (d, J = 8.1 Hz, 1 H) 3.81 (quin, J = 7.6 Hz, 1 H) 1.45 ꢀ 1.94 (m, 8 H).
+
MS (ES+) m/z 278.0 [M+H] .
ACS Paragon Plus Environment

Page 29 of 77
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
5
ꢀ(Pyrrolidinꢀ1ꢀylsulfonyl)quinolineꢀ8ꢀol (12). Step 1. 8ꢀFluoroquinoline 31 (10.5 g,
7
1.3 mmol) was added dropwise with stirring to chlorosulfonic acid (10 mL, 150.4 mmol). The
o
resulting mixture was stirred at 110 C for ~30 hours. The crude mixture was added dropwise to
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
ice water with stirring, causing solids to precipitate. Solids were collected by filtration, rinsed
with a small amount of water and dried under reduced pressure to afford 8ꢀfluoroquinolineꢀ5ꢀ
1
sulfonyl chloride 32 (12.5 g, 71% yield) as a white solid. H NMR (400 MHz, DMSOꢀd ) δ ppm
6
9
.36 (d, J = 8.59 Hz, 1 H) 9.04 (d, J = 3.28 Hz, 1 H) 8.02 (dd, J = 8.08, 5.31 Hz, 1 H) 7.82 (dd,
+
J = 8.72, 4.42 Hz, 1 H) 7.62 (dd, J = 10.61, 8.08 Hz, 1 H). MS (ES+) m/z 246.0 [M+H] .
Step 2. To a suspension of 8ꢀfluoroquinolineꢀ5ꢀsulfonyl chloride 32 (2.0 g, 8.1 mmol) in
THF (25 mL) was added DIPEA (2.8 mL, 16.2 mmol) at ambient temperature. Pyrrolidine (0.67
mL, 8.1 mmol) was added slowly dropwise as a solution in THF (5 mL). Meanwhile to a slurry
of sodium hydride (977 mg, 24.4 mmol) in THF (15 mL) was added 2ꢀ(trimethylsilyl)ethanol
(3.5 mL, 24.4 mmol). After complete addition of pyrrolidine to the 8ꢀfluoroquinolineꢀ5ꢀsulfonyl
chloride a HPLC chromatogram confirmed the first step was complete. This sulfonamide
mixture was added to the slurry of trimethylsilylethanol sodium salt slowly dropwise. The
reaction was allowed to stir at ambient temperature for one hour. The reaction was quenched by
addition of water. Ethyl acetate was added and the layers were separated. The aqueous layer
was extracted (3 X 50 mL) with ethyl acetate. The organics were combined, dried over sodium
sulfate, concentrated to a residue and purified by silica chromatography (100 g) eluting 0ꢀ100%
ethyl acetate/hexanes. Isolated 2.2 g (70% yield) of trimethylꢀ[2ꢀ[(5ꢀpyrrolidinꢀ1ꢀylsulfonylꢀ8ꢀ
1
quinolyl)oxy]ethyl]silane 58. H NMR (400 MHz, DMSOꢀd ) δ ppm 8.88 ꢀ 9.08 (m, 2 H) 8.14
6
(
d, J = 8.59 Hz, 1 H) 7.75 (dd, J = 8.84, 4.04 Hz, 1 H) 7.35 (d, J = 8.59 Hz, 1 H) 4.21 ꢀ 4.47 (m,
ACS Paragon Plus Environment