Scholarly article on 4-[(4-chlorophenyl)(hydroxy)pyridin-3-ylmethyl]benzonitrile 1374584-09-4 from Journal of Medicinal Chemistry p. 4189

Article

pubs.acs.org/jmc

Analogues of Fenarimol Are Potent Inhibitors of Trypanosoma cruzi

and Are Eﬃcacious in a Murine Model of Chagas Disease

Martine Keenan,*^,†Michael J. Abbott,^†Paul W. Alexander,^†Tanya Armstrong,^‡Wayne M. Best,^†

Bradley Berven,^†Adriana Botero,^‡Jason H. Chaplin,^†Susan A. Charman,^§Eric Chatelain,^∥

Thomas W. von Geldern,^∥Maria Kerfoot,^‡Andrea Khong,^‡Tien Nguyen,^§Joshua D. McManus,^†

Julia Morizzi,^§Eileen Ryan,^§Ivan Scandale,^∥R. Andrew Thompson,^‡Sen Z. Wang,^†and Karen L. White^§

^†Epichem Pty Ltd, South Street, Murdoch, WA 6150, Australia

^‡Murdoch University, South Street, Murdoch, WA 6150, Australia

^§Centre for Drug Candidate Optimisation, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia

^∥Drugs for Neglected Diseases initiative (DNDi), 15 Chemin Louis Dunant, 1202 Geneva, Switzerland

S

* Supporting Information

ABSTRACT: We report the discovery of nontoxic fungicide fenarimol (1) as an inhibitor of Trypanosoma

cruzi (T. cruzi), the causative agent of Chagas disease, and the results of structure−activity investigations

leading to potent analogues with low nM IC₅₀s in a T. cruzi whole cell in vitro assay. Lead compounds

suppressed blood parasitemia to virtually undetectable levels after once daily oral dosing in mouse models

of T. cruzi infection. Compounds are chemically tractable, allowing rapid optimization of target biological

activity and drug characteristics. Chemical and biological studies undertaken in the development of the

fenarimol series toward the goal of delivering a new drug candidate for Chagas disease are reported.

damage to these (and other) organs and tissues over time. The

challenge in development of new drugs to treat Chagas disease

lies in demonstrating eﬃcacy in the chronic form of the disease,

a condition diﬃcult to model in the laboratory and to monitor

in clinical trials due to the lack of validated measures of clinical

outcome.

INTRODUCTION

■

Chagas disease is currently endemic in 21 countries across Latin

America, killing more people in the region each year than any

other parasite-born disease including malaria. Moreover, its

prevalence is growing in nonendemic developed countries,

including Australia, USA, Japan, and Spain, such that the global

health burden is around 10 million cases and 25 million people

at risk.¹⁻³Recent eﬀorts from Product Development Partner-

ships (PDPs) such as the Drugs for Neglected Diseases initiative

(DNDi) have brought this parasitic disease to the forefront of

research eﬀorts into neglected diseases,⁴expanding on decades

of work undertaken in Central and South America and in

dedicated laboratories worldwide.^5,6

The current standard of care benznidazole (Chart 1), a

nitroimidazole, works well in the acute phase of the disease, but

Chart 1

The causative parasitic agent of Chagas disease, Trypanosoma

cruzi, is transmitted to animals and humans via insect vectors

known colloquially as “kissing bugs”.⁷Metacyclic trypomasti-

gotes are released in the feces of the triatomine insect vector as

it takes a blood meal and enter the bloodstream via the bite

wound or a mucosal membrane. Once inside the host, metacyclic

trypomastigotes invade nearby cells and diﬀerentiate into an

intracellular amastigote form which multiplies by binary ﬁssion.

Transformation into trypomastigotes occurs prior to release from

cells back into the bloodstream, proliferating the infective cycle.

Other forms of transmission include congenital, blood trans-

fusion and, to a lesser extent, contaminated food.

The disease progresses through an acute and then indeterminate

phase, presenting as a chronic illness some 10−15 years post-

infection, at which point mortality is high.⁸This occurs as

parasites move from the bloodstream to the muscle cells of

the heart and/or the gastrointestinal tract, causing extensive

clinical eﬃcacy in patients with the chronic illness is limited and

controversial. Originally thought to act via the production of

Received: November 22, 2011

Published: April 27, 2012

4189

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

free radicals and reactive metabolites promoting damage

to parasite DNA,⁹benznidazole is now proposed to undergo

enzyme-mediated activation by nitroreductases within the

parasite.¹⁰It can cause undesirable side eﬀects in adults ranging

from gastrointestinal discomfort to neuropathy, leading to poor

patient compliance over the required 60-day treatment

regime.¹¹Posaconazole¹²and a pro-drug of ravuconazole¹³

(Chart 1) are the ﬁrst new agents to enter clinical trials for

the treatment of Chagas disease in over 40 years. Originally

developed to target human fungal conditions and part of a large

family of azole-derived antifungals, these compounds interrupt

sterol biosynthesis in T. cruzi by inhibiting lanosterol 14α-

demethylase (CYP51), an enzyme required to demethylate

lanosterol an important intermediate in the biosynthetic path-

way.^14,15Concern regarding the potential for development

of resistance to azole-based therapies suggests there is still a

need for new treatments for Chagas disease.^16,17These must

be better tolerated than benznidazole, active against various

T. cruzi strains, and eﬃcacious in the chronic phase of the illness.

As part of a hit generation eﬀort to discover new T. cruzi

inhibitors, a diversity set of agrochemicals was prepared and

screened in an in vitro whole cell parasite assay against a

the synthesis, structure−activity and structure−property

relationships, and in vivo evaluation of 1 and analogues as

part of a drug discovery program to develop new treatments for

Chagas disease.

RESULTS AND DISCUSSION

■

Chemistry. Compound 1 was originally developed by agro-

chemical company Elanco and later investigated as an estrogen

synthetase inhibitor.²¹Preparation of most triarylcarbinol com-

pounds (III) reported in this study was carried out by analogy

to these literature methods, introducing the three aromatic

domains (designated as the heterocycle, R₁, and R₂) in a step-

wise fashion (Scheme 1). Key intermediate benzophenones (II)

were easily prepared in large quantities from activated car-

boxylic acids (I, general methods A1−3) by either Friedel−

Craft acylation (general method B1), palladium-catalyzed

acylation of aryl boronic acids (general method B2),²²or by

addition of aryl organometallic derivatives to the appropriate

N-methoxy-N-methyl benzamides (general method B3). Some

benzophenones were also purchased from commercial sources.

Organometallic methods were used to introduce the remaining

(hetero)aryl group to give the target triarylcarbinols (III)

in overall good yields (general method C). In the case of the

pyrimidinyl derivatives, the lithio-pyrimidine species was

generated in situ at low temperature in the presence of the

benzophenone to minimize side reactions (general method C

(pyrimidine)). The general methods depicted in Scheme 1

were used to introduce both aryl and heteroaryl groups, provid-

ing a very ﬂexible route to a broad range of analogues.

Potassium ferricyanide was used to convert arylbromides to

the corresponding benzonitriles (IV, general method D).²³

Tertiary carbinols were dehydroxylated on reaction with stannous

chloride according to literature procedures^21b(V, general

method E) or substituted by conversion to the corresponding

chloro compound followed by reaction with the desired

nucleophile (VI, general method F). The intermediate chloro

derivative was easily hydrolyzed back to the hydroxy com-

pound, which was typically observed in the ﬁnal product mix-

ture before puriﬁcation. Compounds were prepared in racemic

form.

́

T. cruzi strain (Tulahuen) belonging to T. cruzi group VI

(TcVI)¹⁸and transfected with the β-galactosidase gene.¹⁹The

plant fungicides fenarimol (1) and pyrifenox (2), used in the

control of powdery mildew and fungus on fruits and vegetables,

demonstrated good activity in the assay with IC₅₀s of 350 nM

(1) and 290 nM (2) (Figure 1). Compound 1 has recently

Figure 1. Fenarimol (1) and Pyrifenox (2).

been reported to be a modest inhibitor of related protozoan

parasite Leishmania donovani,²⁰and with simple aromatic com-

ponents and an uncomplicated synthesis we considered it a

suitable starting hit for further development. This article reports

Compounds prepared were assayed in the T. cruzi whole

parasite assay described above with cytotoxicity in L6 cells

Scheme 1. General Methods for the Preparation of 1 and Analogues

4190

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

(rat myoblasts from skeletal muscle) used as a counter screen.

No signiﬁcant cytotoxicity was observed for any of the com-

pounds, with a minimum selectivity index for T. cruzi over cell

toxicity of ca. 100-fold increasing to >500-fold for the most

highly optimized analogues.

incorporate methoxy (20), nitrile (21), and amine (22) groups

yielded compounds more active than 9, but these changes were

of no particular physicochemical or pharmacokinetic beneﬁt

(Table 2). Bulky amine derivative 23 was less active, and R₃

Structure−Activity Relationship (SAR). The three

aromatic components of 1 (Scheme 1) naturally lent them-

selves to separate domains for variation in the SAR inves-

tigations: (i) 5-pyrimidyl (heterocycle), (ii) 4-chlorophenyl

(R₁), and (iii) 2-chlorophenyl (R₂), and the importance of the

hydroxyl substituent (R₃) was also investigated.

Table 2. SAR Study of R₃with Some Variation of the

Heterocycle and R₂

Variation of the Heterocycle. Keeping R₁as 4-

chlorophenyl and making simple substitutions to R₂, the

impact of the heterocycle on activity was explored (Table 1).

a

b

IC₅₀Tc (L6)

compd

R₂

R₃

heterocycle

3-pyridine

(μM)

20

21

22

23

24

25

26

27

28

2Cl-Ph

4Cl-Ph

2Cl-Ph

4Cl-Ph

2Cl-Ph

OCH₃

CN

NH₂

NHiBu

H

0.090 (58.7)

0.050 (56.8)

0.090 (76)

3-pyridine

Table 1. SAR Study of Heterocycle Moiety with Some

Variation of R₂

3-pyridine

0.606 (59.2)

1.07 (>100)

0.683 (70.1)

0.230 (62.3)

0.080 (84.7)

5-pyrimidine

3-pyridine

H

3-pyridine

heterocycle

OH

5-pyrimidine-N-oxide

14.53 (>100)

a

b

5-pyrimidine

3-pyridine

Tc = T. cruzi, values are the mean of at least two experiments. L6 cells

a

b

a

b

(rat myoblasts from skeletal muscle) for assessment of cytotoxicity.

IC₅₀Tc (L6)

R₂

compd

(μM)

compd

(μM)

2Cl-Ph

4Cl-Ph

4CH₃-Ph

2F-Ph

1

3

4

5

6

7

8

0.350 (76.8)

0.220 (47.2)

0.024 (67.4)

0.140 (>100)

0.840 (>100)

0.144 (58.7)

0.197 (66.8)

9

0.270 (61.3)

0.095 (49)

0.017 (61)

0.035 (>100)

0.100 (66)

0.031 (57)

0.008 (56.4)

equal to ﬂuorine was relatively unstable and readily hydrolyzed

back to the starting alcohol. Removal of the hydroxyl group

(R₃= H) reduced activity by 3-fold for pyrimidinyl analogues

24 and 25, while activity of the pyridyl analogues 26 and 27 was

not aﬀected. N-Oxide 28 was signiﬁcantly less active than 1,

emphasizing the important binding interaction of the nitrogen

atom.

Variation of R₁. Maintaining R₂as 2-chlorophenyl and

varying R₁gave compounds as much as 10-fold less active than

9 (data not shown), and we quickly moved on from this area of

the SAR.

10

11

12

13

14

15

3F-Ph

4Br-Ph

4CF₃-Ph

2-pyrazine

2-pyridine

a

b

a

b

R₂

compd

IC₅₀Tc (L6)

compd

IC₅₀Tc (L6)

(μM)

2Cl-Ph

16

0.440 (>100)

18

27.0 (>100)

2-pyrimidine

4-pyrimidine

Variation of R₂. The R₂SAR study, keeping variations of R₁

to a minimum, was very productive and revealed clear SAR

trends (Table 3). An electronic eﬀect on activity was not evident

following monosubstitution at 3- and 4-positions of R₂, with

methoxy, bromo, and nitrile analogues (entries 30, 31, 37, 14,

41, and 42) spanning only a 2−3-fold potency range. Introduc-

tion of lipophilic substituents to the para position of R₂was

very beneﬁcial, with 4-i-propoxy (34), -triﬂuoromethyl (15),

-dimethylamino (51), and -i-propyl (52) analogues achieving

activities in the low nM range. Interestingly, 4-nitrile analogue

43 was also highly active, contradicting the lipophilicity for

activity enhancement trend, and the relatively good activity of

3-amido analogue 46 was also somewhat surprising given the

more hydrophilic nature of this molecule. Activity was im-

proved by introduction of a 2-ﬂuoro substituent for some

analogues such that 2,4-disubstituted analogues (e.g., com-

pounds 44, 45, 54, and 60) were up to 10-fold more active than

the des-ﬂuoro comparator compounds, but this was not observed

in all cases (compounds 47 and 56). A certain amount of mixing

and matching was required for optimal combinations of

substituents to give the most active compounds as exem-

pliﬁed by 44 and 60 (1−2 nM). Symmetrical analogues 61−63

did not give additive potency eﬀects, reinforcing the distinction

in the binding interactions for R₁and R₂.

a

b

a

b

R₂

compd

IC₅₀Tc (L6)

compd

IC₅₀Tc (L6)

(μM)

2Cl-Ph

17

22.9 (>100)

19

7.05 (>100)

a

b

Tc = T. cruzi, values are the mean of at least two experiments. L6 cells

(rat myoblasts from skeletal muscle) for assessment of cytotoxicity.

It was clear from the data that replacement of 5-pyrimidine

with 3-pyridine led to signiﬁcant improvements in potency

(compounds 9, 10, and 12−15), with activity reaching low nM

values with R₂as 4-triﬂuoromethylphenyl (15). Pyrazine ana-

logue 16 was equipotent with 1, while analogues 18−19 indi-

cated a nitrogen in the 3-position was necessary for activity.

Compound 9 was taken forward as the comparator compound

for further optimization.

Compounds prepared containing a selection of heterocycles

other than pyridine, pyrimidine, and pyrazine such as quinoline,

indole, isoxazole, furan, thiophene, and triazole were notably

less active (IC₅₀> 1 μM) or inactive (IC₅₀> 10 μM). This re-

sult is consistent with T. cruzi CYP51 inhibition as the probable

mode of action for this series analogous to azole antifungals like

posaconazole. Consequently, an optimally placed, sterically un-

encumbered heme-iron binding atom such as nitrogen is crucial

for activity.

Hydroxyl SAR (R₃). Keeping R₁as 4-chlorophenyl and once

more making simple substitutions to R₂, manipulation of R₃to

The low nM in vitro activity of the most highly opti-

mized analogues in Table 3 compared favorably to structurally

4191

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

Table 3. SAR Study of R₂with Some Variation of R₁

a

b

a

b

IC₅₀Tc (L6)

compd

R₁

R₂

(μM)

compd

R₁

R₂

(μM)

29

11

30

31

32

33

34

35

36

37

14

38

39

40

15

41

42

43

44

4Cl-Ph

4CF₃−Ph

4Cl-Ph

4CF₃-Ph

4Cl-Ph

4CF₃-Ph

2CH₃-Ph

4CH₃-Ph

3OCH₃-Ph

4OCH₃-Ph

2OiPr-Ph

3OiPr-Ph

4OiPr-Ph

2Br-Ph

0.370 (82)

0.017 (61.2)

0.060 (85.6)

0.040 (68.1)

0.446 (48.3)

0.082 (67.6)

0.002 (56.6)

0.004 (47.6)

0.070 (55.2)

0.054 (54.1)

0.031 (57)

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

4Cl-Ph

2F, 4Cl-Ph

3CONH₂-Ph

4CONH₂-Ph

4NHSO₂Me-Ph

4NMe₂-Ph

4iPr-Ph

0.010 (59.4)

0.030 (>100)

0.025 (>100)

0.070 (>100)

0.120 (>100)

0.030 (>100)

0.006 (59.1)

0.002 (56.3)

0.016 (70.2)

0.002 (>100)

0.021 (57.4)

0.026 (79.2)

0.026 (58.2)

0.026 (>100)

0.003 (62.6)

0.001 (56)

4Cl-Ph

2F, 4Cl-Ph

4CF₃-Ph

4Cl-Ph

4CF₃-Ph

4Cl-Ph

2,4F-Ph

3Br-Ph

4CF₃-Ph

4Cl-Ph

2F, 4Cl-Ph

2F, 4CF₃-Ph

2F, 4Br-Ph

2F, 4OiPr-Ph

2F, 4CN-Ph

2F, 4CH₃-Ph

2F, 4Cl-Ph

4OiPr-Ph

4Br-Ph

0.020 (54.7)

0.120 (59.3)

0.070 (60.4)

0.008 (56.4)

0.110 (>100)

0.070 (>100)

0.012 (76.5)

0.002 (56.1)

4Cl-Ph

2CF₃-Ph

3CF₃-Ph

4CF₃-Ph

3CN-Ph

4CN-Ph

2F, 4CN-Ph

4Cl-Ph

4OiPr-Ph

4CF₃-Ph

2F, 4Cl-Ph

0.016 (61.4)

0.015 (50.6)

0.016 (56.3)

4CF₃-Ph

2F, 4Cl-Ph

a

b

Tc = T. cruzi, values are the mean of at least two experiments. L6 cells (rat myoblasts from skeletal muscle) for assessment of cytotoxicity.

complex benchmark T. cruzi CYP51 inhibitor posaconazole

(IC₅₀0.7nM) and was superior to benznidazole (IC₅₀1.15 μM).

Heterocyclic variations of R₂(Table 4) gave active com-

pounds, although activity decreased with increasing polarity of

the heterocyclic ring. Thiophene and benzothiophene analogues

(64−67) were more active than thiazole analogues 68 and 69,

although the activity of the latter compound could be increased

by a 2-amido group (71) but decreased on addition of a 2-chloro

substituent (72). The weak activity of pyrimidyl analogue 73 was

improved by addition of key substituents identiﬁed from the

R₂phenyl SAR studies (Table 3) such that the addition of an

i-propoxyl group to R₂(75) and a 2-ﬂuoro substituent to R₁(76)

made a signiﬁcant impact on activity.

Pharmacokinetic Properties. Throughout the activity

optimization process, we were mindful of preparing compounds

with good pharmaceutic and pharmacokinetic properties to

facilitate compound proﬁling in vivo in T. cruzi mouse models.

As a result, we may not have fully exploited the potential for

activity enhancement obtained from making R₂increasingly

lipophilic, cutting short SAR leads that resulted in high in vitro

metabolism for example. Table 5 summarizes the in vitro

microsomal metabolism, solubility at pH 6.5, and inhibition of

cytochrome P450 3A4/5 (CYP3A4/5) in human liver micro-

somes of lead compounds from the SAR studies. Compounds

were typically found to have low to moderate solubility and

moderate to high rates of metabolism in human and rat liver

microsomes. The high stability in microsomes and good solu-

bility of compound 73 was the basis for our interest in pursuing

the SAR of this molecule. An i-propoxyl moiety proved to be a

metabolic liability across several analogues (34, 60, and 76),

while compounds 43−45 and 54 were of speciﬁc interest given

the low nM activity coupled with more moderate metabolic

stability. Likewise, primary amide analogue 46 was relatively

stable in hepatic microsomes with greatly improved solubility.

Table 4. SAR Study of R₂(Heterocycles) with Some

Variation of R₁

a

b

IC₅₀Tc (L6)

compd

R₁

R₂

2-thiophene

(μM)

64

65

66

67

68

69

70

71

72

73

74

75

76

4Cl-Ph

0.013 (67.7)

0.005 (>100)

0.078 (>100)

0.020 (58.7)

0.201 (>100)

0.140 (>100)

0.260 (56)

2F, 4Cl-Ph

4Cl-Ph

2-thiophene

3-thiophene

4CF₃-Ph

4Cl-Ph

2-benzothiophene

2-thiazole

4Cl-Ph

5-thiazole

4Cl-Ph

(2NH₂)-5-thiazole

(2NHCOiPr)-5-thiazole

(2Cl)-5-thiazole

5-pyrimidine

4Cl-Ph

0.021 (56.6)

0.490 (>100)

1.53 (>100)

0.304 (>100)

0.060 (>100)

4Cl-Ph

4OiPr-Ph

4Cl-Ph

2Cl-5-pyrimidine

2OiPr-5-pyrimidine

2F, 4Cl-Ph

0.008 (89.5)

a

b

Tc = T. cruzi, values are the mean of at least two experiments. L6

cells (rat myoblasts from skeletal muscle) for assessment of

cytotoxicity.

4-Triﬂuoromethyl was a particularly desirable substituent pro-

viding a measurable increase in metabolic stability while main-

taining excellent potency (compounds 43, 44, and 54), and for

later compounds R₁was ﬁxed as a 4-triﬂuoromethylphenyl motif.

Apart from the generally poor to moderate aqueous solubility

at pH 6.5, all of the compounds had predicted physicochem-

ical characteristics suggesting they should have no signiﬁcant

permeability limitations in vivo. The inhibition of CYP3A4/5

4192

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

Table 5. Representative In Vitro Metabolism and Solubility

Data for 1 and Analogues

Table 6. Plasma Concentrations in Mice Following Oral

Administration

a

metabolism

dose

C_1h

C_8h

C_24h

compd

(mg/kg)

(μM)

CYP3A4/5

b

1

20

100

20

2.1

9.6

0.08

0.6

ND

0.03

0.25

0.05

ND

0.06

ND

0.006

0.003

ND

2.9

compd

E_H(h) E_H(r) solubility (μg/mL)

(IC₅₀μM)

c

34

43

1

0.82

0.83

0.89

0.87

0.5

0.62

0.81

0.88

0.91

0.5

12.5−25

3.1−6.3

1.6−3.1

6.3−12.5

1.6−3.1

50−100

<1.6

66% at 20 μM

2.5

0.4

9

0.6

50

11.8

1.4

3.6

34

35

43

44

45

46

47

54

60

73

76

1.9

44

46

20

0.3

1.4

10

6.8

0.4

7.6

20

10.3

13.7

19.5

10.5

1.24

0.3

1.9

0.64

0.39

0.2

0.67

0.58

0.48

0.45

0.44

0.95

0.37

0.88

4.1

50

15.9

6.5

0.9

100

20

2.6

47

0.44

0.23

<LLQ

13.6

11.1

<0.2

3.9

54

20

0.54

0.9

1.4

73

20

1.6−3.1

>100

1.1

posaconazole

20

6.3

0.27

0.69

0.42

5

4.4

50

6.4

3.8

12.5−25.0

3.1−6.3

a

C_{1h, 8h, 24h}, = compound concentration in mouse plasma at 1 h, 8 h and

24 h, respectively; ND = not determined; <LLQ = less than the ana-

lytical limit of quantitation (0.002 μM)

posaconazole

<0.2

98% at 20 μM

a

Microsome predicted hepatic extraction ratio (E_H) determined in

human (h) and rat (r) liver microsomes. Kinetic solubility at pH 6.5

determined by nephelometry. E_Hvalue for mouse liver microsomes

b

c

Table 7. Pharmacokinetic Parameters in Rats Following

Intravenous (IV) and Oral Administration

has signiﬁcant ramiﬁcations for adopting a combination therapy

approach as a means to treat Chagas disease, a strategy widely

favored to prevent drug resistance. Lead compounds in the

fenarimol series demonstrated moderate activity at this enzyme,

with good separation from activity against T. cruzi in vitro and

signiﬁcantly improved T. cruzi:CYP3A4/5 activity ratios relative

to benchmark compound posaconazole, a very potent inhibitor

of CYP3A4/5.

a

b

c

d

IV dose half-life

blood CL

V_ss

oral dose bioavailability

compd (mg/kg) (h) (mL/min/kg) (L/kg) (mg/kg)

(%)

43

46

76

5.2

4.2

4.8

5.1

6.1

24.4

18.9

73.9

5.7

3.6

9.1

17.6

15.2

15.7

68.1

95.0

7.4

11.3

a

b

c

Elimination half-life. Blood clearance. Apparent volume of distribu-

d

tion at steady state. estimated by calculating and comparing the average

dose-normalized AUC_0‑infafter oral administration to the average dose-

normalized AUC_0‑infafter IV administration

The in vivo pharmacokinetic properties of selected lead com-

pounds were studied in noninfected, male Swiss Outbred mice

following a single oral dose of up to100 mg/kg. The overall

trend for oral exposure was in line with the microsomal metabolic

stability data, such that compounds with predicted high hepatic

extraction ratios appeared to be more rapidly cleared in vivo. 46

and 47 showed the highest maximum plasma concentrations

after oral administration, which is consistent with them being

among the least lipophilic and most soluble of the selected

compounds at intestinal pH. 73 which appeared to have the

highest solubility achieved only low plasma concentrations

in vivo (Table 6). As the discovery program evolved, it was

evident that extended (greater than 24 h) plasma exposure was

an important determinant of in vivo eﬃcacy and the com-

pounds which showed good eﬃcacy had plasma concentrations

several-fold higher than their respective in vitro IC₅₀values at

24 h postdose. Indeed, 24 h plasma concentrations for the

in vivo benchmark compound, posaconzole, were more than

400 times higher than the in vitro IC₅₀at 24 h postdose

(20 mg/kg). In rats, the blood clearances of 43, 46, and 76 after

intravenous (IV) administration correlated well with the in

vitro data in rat liver microsomes. After oral administration, 46,

which had the highest solubility and lowest blood clearance of

the three compounds, showed the highest bioavailability of

95%, whereas 76, with moderately low aqueous solubility and

high blood clearance, had a bioavailability of only 7% (Table 7).

In Vivo Eﬃcacy. The in vivo eﬃcacy of compounds pos-

sessing good oral exposure and high in vitro potency was eval-

uated in an in-house model of Chagas disease. In this model,

compounds are investigated for their ability to reduce blood

parasitemia levels in mice arising from an established T. cruzi

infection derived from a sublethal dose of 25000 bloodstream forms

of T. cruzi (TcVI; Tulahuen strain). Test compounds were admin-

́

istered once daily starting on day 8 post infection (pi), with

posaconazole and vehicle-only treated groups included as controls.²⁴

Five-Day Dosing Model. As a ﬁrst indicator of in vivo

eﬃcacy, compounds 1 and 46 were dosed once daily at 100

mg/kg for 5 days (Table 8). While the activity of 1 was

Table 8. In Vivo Eﬃcacy of Selected Compounds in T. cruzi

Infected Mice after 5-Day Dosing

a

dose

parasitemia

d

b

c

compd

(mg/kg) days route survival

reduction (%)

1

100

50

20

50

10

2

5

ip

5/5

4/5

5/5

3/5

4/4

80

>95

65

46

po

0

posaconazole

100

a

b

Once daily. ip = intra peritoneal injection; po = per os (oral

c

administration). Survival is indicated by (number of mice surviving)/

(total number infected and treated). Percentage eﬃcacy calculated

d

by: ([av parasitemia vehicle group − av parasitemia treated group)/av

parasitemia vehicle group] × 100%).

relatively weak, 46 demonstrated good eﬃcacy following oral

dosing and successfully decreased blood parasitemia to virtually

4193

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

Table 9. In Vivo Eﬃcacy of Selected Compounds in T. cruzi Infected Mice after 20-Day Dosing

a

b

c

d

e

compd

dose (mg/kg) days route

survival

parasitemia reduction (%)

no. of cycles of immunnosuppression before parasite rebound

43

20

100

20

po

4/5

5/5

>99

rebound after 3 cycles

benznidazole

posaconazole

f

14/15

parasite free after 3 cycles (8/14)

g

“CURE” (5/8)

a

b

c

Once daily. po = per os (oral administration). Survival is indicated by (number of mice surviving)/(total number infected and treated).

d

e

Percentage eﬃcacy calculated by: ([av parasitemia vehicle group − av parasitemia treated group)/av parasitemia vehicle group] × 100%). One

f

cycle of immunosuppression = treatment with 50 mg/kg/day cyclophosphamide for 4 days, followed by 3 days rest. Combined results from three

separate experiments. “CURE” conﬁrmed by PCR of tissue samples.

g

undetectable levels (>95% inhibition) after ﬁve doses. Addi-

tional experiments with 50 and 20 mg/kg doses of 46 proved to

be less eﬀective and inactive, respectively, indicating a dose-

dependent response.

PCR of tissue samples (not shown).²⁶The inconsistent ability

of a clinical benchmark compound to demonstrate “cure” high-

lights how diﬃcult it is to model the chronic form of infection

in the laboratory.

Even though “cure” was not achieved with compound 43 in

this model, the level of eﬃcacy demonstrated in such a

stringent test of in vivo eﬃcacy is very promising. The low dose

of 43 required for parasite suppression showed similar eﬃcacy

to a much higher dose of current drug therapy benznidazole,

and in contrast to posaconazole, the synthetic tractability of the

series meets the “low cost of goods” criteria relevant to drugs

produced in a “not-for-proﬁt” environment. Follow-up com-

pounds are in preparation.

Posaconazole was more eﬀective than 46, eﬃciently clearing

parasites from the blood even at low doses (2 mg/kg).

Ten-Day Dosing Model. Compound dosing was extended

to 10 days to determine if eﬃcacy could be improved with a

longer treatment time. Mice were treated once daily for 10 days

with a 50 mg/kg oral dose of compound 43, which successfully

decreased parasitemia to undetectable levels in blood by the

end of the treatment period. The experiment was extended into

a further 10 day rest period (no compound administered)

to allow for parasites in tissues to re-enter the blood from

sanctuary sites. Analysis of blood samples on day 21 after this

rest period indicated mice were still (apparently) parasite free.

To determine if parasites were fully cleared from organs, the

experiment was taken further into a subchronic phase and

animals were immunosuppressed on treatment with cyclo-

phosphamide (one treatment cycle = 4 days cyclophosphamide

at 50 mg/kg/day followed by 3 days rest)²⁵to further facilitate

the return of any existing parasites into blood following with-

drawal of immune control.

In this very stringent form of the assay, parasites were ob-

served in the blood of mice treated with 43 after two cycles of

immunosuppression indicating a 50 mg/kg/day 10 day oral

treatment of 43 had not fully cleared all parasites from sanc-

tuary sites and thus had not “cured” the mice. Nonetheless,

the eﬃcacy of 43 was very encouraging and compared favorably

to a 20 mg/kg/day 10 day oral treatment of benchmark

compound posaconazole, for which parasite rebound was also

observed after the second cycle of immunosuppression.

Twenty-Day Dosing Model. In a ﬁnal optimization of the

model, infected mice were treated with compound once daily

for 20 days, left to rest for 10 days (no compound admin-

istered), and if parasites were undetectable in blood, animals

were immunosuppressed for a maximum of three cycles (as

described above). Table 9 illustrates the outcome of the

treatment of infected mice under this regimen.

CONCLUSION

■

Fenarimol, a nontoxic fungicide, was identiﬁed as a moderately

potent inhibitor of T. cruzi during a targeted screening exercise

to ﬁnd hits for a drug discovery program aimed at developing

new treatments for Chagas disease. Subsequent SAR inves-

tigations led to the preparation of very active, low nM T. cruzi

inhibitors easily prepared in multigram quantities in ﬁve steps

or fewer in racemic form. The inclusion of routine physico-

chemical and pharmacokinetic proﬁling as part of the

optimization cycle facilitated rapid identiﬁcation of compounds

suitable for proﬁling in mouse models of T. cruzi infection.

Compound 43 was eﬃcacious in a stringent model of estab-

lished infection, suppressing parasitemia to negligible levels

after daily oral dosing at 20 mg/kg/day for 20 days, with

parasite rebound in blood only occurring after mice were

subjected to three cycles of immunosuppression. This eﬃcacy

was matched by a much higher dose of Chagas disease standard

of care benznidazole. Compounds in the fenarimol series represent

an exciting addition to the Chagas drug discovery landscape,

and further optimization is ongoing.

EXPERIMENTAL SECTION

■

Posaconazole was purchased as the oral suspension (Noxaﬁl Schering

Corporation, 40 mg/mL). For in vivo eﬃcacy and pharmacokinetic

studies, the oral suspension was diluted to the appropriate concen-

tration with water. For in vitro studies, posaconazole was ﬁrst isolated

from the suspension by dilution with water and centrifugation, followed

by extraction and recrystallization from hot i-propyl alcohol.

Lead compound 43 performed well under these stringent

conditions, and following a 20 mg/kg/day oral dose of 43 for

20 days, parasites were not observed in blood until after

the third cycle of immunosuppression had been completed.

A 100 mg/kg/day treatment with benznidazole demonstrated

the same level of eﬃcacy as 20 mg/kg/day of 43. The results

reported for posaconazole are combined from three separate

20 day dosing experiments. A combined total of 8/14 mice

treated with 20 mg/kg of posaconazole daily for 20 days

remained parasite-free after the full course of immunosuppres-

sion (3 cycles), but only 5/8 of these animals were deemed

“cured”, i.e., negative for parasites in organs as conﬁrmed by

Biology: In Vitro T. cruzi Assay for Determination of IC₅₀.

This assay uses T. cruzi Tulahuen trypomastigotes expressing the β-

́

galactosidase gene, obtained from Dr Fred Buckner (University of

Washington) and using their published protocol.¹⁹The parasites were

maintained in vitro by serial passage in L6 cells. Brieﬂy, L6 cells were

plated into 96 well, ﬂat-bottom tissue culture plates and incubated at

37 °C in 5% CO₂for 24 h to allow cells to adhere. T. cruzi trypo-

mastigotes were then added at a multiplicity of infection of 3, and

plates were incubated for a further 48 h to allow infection to establish.

All steps were carried out using RPMI media 1640 (without phenol

red) supplemented with 10% Foetal Bovine Serum (FBS, Bovogen).

4194

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

Extracellular trypomastigotes were then removed and compounds

were added in seven-point serial dilutions performed in triplicate.

Benznidazole (Epichem Pty Ltd.) was included as a control. After

96 h of incubation with the compounds, the colorimetric agent,

chlorophenol red-ﬂ-^D-galactopyranoside (CPRG, Roche) was added

with 0.3% v/v Nonidet P-40. After 4−6 h, a color change following

catabolization of the reagent by viable T. cruzi was observed and

absorbance was read at 530 nm using a Dynex microplate reader. The

% inhibition was calculated by the following equation: %inhib = 100 −

[(T. cruzi with compound − compound only)/(T. cruzi only − media

only)] × 100. For each compound, % inhibition values were used to

generate a standard curve from which the IC₅₀was calculated. Each

assay was performed at least twice, and the average was used.

In Vitro Assay for Determination of Cytotoxicity. L6 cells

were cultured in RPMI 1640 supplemented with 10% FBS in 96-well

ﬂat bottom tissue culture plates. Dose−response curve analysis was

conducted by using seven-point serial dilutions performed in triplicate

to determine an IC₅₀value. Cells were exposed to test compounds for

72 h in total. Podophyllotoxin was included in all assays as a control,

and each assay was performed at least twice to obtain an average IC₅₀

value. Alamar Blue (AbD Serotec) was added to the plates, allowing

for a color change through metabolic oxidation−reduction by pro-

liferating cells, and absorbance was read on a Dynex microplate reader

at 570 and 630 nm.

Mountain View, CA) was utilized for estimation of the terminal

elimination half-life (t_1/2), the area under the plasma concentration

versus time proﬁle extrapolated to inﬁnity (AUC_0−inf), plasma clear-

ance, and volume of distribution at steady state (V_dss). The blood

clearance (CL) was estimated by dividing the plasma clearance by the

blood to plasma ratio determined in vitro. The oral bioavailability was

estimated by comparing the average dose-normalized AUC_0−infafter

oral administration to the average dose-normalized AUC_0−infafter IV

administration.

In Vivo Anti-T. cruzi Activity. Mice. Outbred, female Swiss

mice approximately 8 weeks old were obtained from the Animal

Resources Centre (Perth, Western Australia). All animal experi-

mentation was carried out with approval of the Animal Ethics

Committee of Murdoch University.

Generation of T. cruzi Parasites. T. cruzi parasites (Tulahuen

́

strain) were kindly donated by Dr Vanessa Yardley (LSTMH, UK)

and passaged through adult female Swiss mice to maintain virility.

Trypomastigote-infected blood was collected and frozen in liquid

nitrogen for subsequent infections in mice.

Preparation of Compounds for Dosing. Compounds were sus-

pended in either a hydroxypropylmethylcellulose suspension vehicle

(HPMC-SV; 0.5% w/v hydroxypropylmethylcellulose + 0.4% v/v

Tween 80 + 0.5% v/v benzyl alcohol in deionized H₂O) and given

by oral gavage (43, 46, posaconazole, and benznidazole) or in a

phosphate-buﬀered saline-based vehicle (PBS + 0.4% v/v Tween 80 +

10% v/v polyethylene glycol 400 (PEG400)) and administered by

intraperitoneal (ip) injection (1). Posaconazole (Noxaﬁl) was diluted

to the required concentration using Water for Injection (WFI) for

administration by oral gavage.

In Vivo Pharmacokinetic Studies. Pharmacokinetic studies in

mice and rats were performed in accordance with the Australian Code

of Practice for the Care and Use of Animals for Scientiﬁc Purposes,

and the study protocols were approved by the Monash Institute of

Pharmaceutical Sciences Animal Ethics Committee.

The systemic exposure of compounds 1, 34, 43, 44, 46, 47, 54, 73,

and posaconazole was studied following oral administration in non-

fasted male Swiss Outbred mice weighing 23.8−39.9 g. Mice had

access to food and water continuously throughout the pre- and

postdose phases of the study. Compounds were administered orally

by gavage as either a solution or suspension in an aqueous vehicle

(0.2 mL dose volume per mouse). At predeﬁned time points, blood

samples were collected from mice (n = 1−3 mice per time point for

each compound) via either submandibular-bleed (conscious sampling)

or terminal cardiac puncture (following anaesthetization with gaseous

isoﬂuorane). Blood was transferred to heparinized tubes containing a

stabilization cocktail (Complete inhibitor cocktail, potassium ﬂuoride,

and EDTA) to minimize the potential for ex vivo degradation of

compound. Samples were immediately centrifuged to collect plasma

for analysis as described below.

The pharmacokinetics of 43, 46, and 76 were also assessed in

overnight fasted male Sprague−Dawley rats weighing 272−320 g after

both intravenous (IV) and oral administration. Rats had access to

water ad libitum throughout the pre- and postdose sampling period,

and access to food was reinstated 4 h postdose. Compounds were

administered intravenously in an aqueous solution vehicle as a 10 min

constant rate infusion into the jugular vein (1.0 mL per rat, n = 2 rats

for each compound) and orally by gavage as an aqueous suspension

(1.0 mL per rat, n = 2 rats per compound). Samples of arterial blood

were collected up to 24 h postdose via an in-dwelling carotid cannula.

Blood was collected directly into heparinized tubes containing sta-

bilization cocktail as described above and maintained at 4 °C. At the

end of the collection period, samples were centrifuged to collect plasma

for analysis.

In Vivo Toxicity Testing. Compounds were ﬁrst screened in an in

vivo mouse toxicity assay before evaluation for eﬃcacy in the T. cruzi

subchronic infection model. For toxicity testing, compounds were

solubilized in test vehicle at concentrations of 15 mg/mL. Two mice

were used to assess each compound, with each mouse receiving a

cumulative dose of up to 600 mg/kg over a period of 48 h. This

represents the maximum level of compound which would be admin-

istered to an animal over the course of eﬃcacy testing. Animals were

monitored closely during the treatment period and for an additional

week following the last treatment dose for signs of compound-induced

toxicity. Speciﬁc criteria monitored included body weight, condition,

activity, and hydration. If no adverse eﬀects were observed, com-

pounds were deemed nontoxic and were progressed to in vivo eﬃcacy

testing.

In Vivo Eﬃcacy Testing. Induction of acute T. cruzi infection was

obtained by infecting mice with 25000 trypomastigote forms of

T. cruzi Tulahuen strain via ip injection. Five mice per group were

́

tested for each compound and dosage. Compound administration was

commenced on Day 8 post infection (pi) and continued daily for 5, 10,

or 20 days. Parasitemia was determined by collection of blood by tail

prick on days 8 (prior to dosing), 9, 12, 14, 16, 19, and 27 pi and

counting live trypomastigotes under the microscope using a Neubauer

hemocytometer. Red blood cells were lysed from the samples for ease

of counting using Red Cell Lysing Buﬀer (Sigma). Eﬃcacy was

determined by comparison of parasitemia levels in compound treated

groups to the vehicle only group, and the percentage eﬃcacy was

calculated by: ([av parasitemia vehicle group − av parasitemia treated

group)/av parasitemia vehicle group] × 100%). [Note: in some cases

% could not be calculated, e.g., during extended dosing where vehicle

group does not survive.] If parasitemia levels were no longer detectable

in the blood following compound treatment, animals were immuno-

suppressed to eliminate the possibility of parasitemia being harbored in

tissues/organs. Cyclophosphamide-induced immunosuppression was

commenced 10 days after cessation of dosing. Cyclophosphamide was

administered ip at 50 mg/kg per day in three cycles; each cycle

comprised 4 days treatment followed by 3 days rest.²⁵Parasitemia was

determined by collection of blood by tail prick as detailed above. As a

ﬁnal measure, the absence of parasites from organs was conﬁrmed by

conducting PCR on tissue samples; those samples that were negative

for T. cruzi DNA were designated as a “cure”.²⁶

Quantitative analysis of each compound in plasma was conducted

by LC-MS (on either a Micromass Quattro Premier, Micromass Xevo

TQ, or Micromass Quattro Ultima PT coupled to an Acquity UPLC;

all from Waters Corporation, Milford, MA) against calibration stan-

dards prepared in blank plasma from the respective species. Both

samples and standards were prepared by precipitation with acetonitrile,

followed by centrifugation and analysis of the supernatant. The

analytical lower limit of quantitation for each compound in plasma

ranged from 0.001 to 0.015 μM.

Intravenous (IV) and oral pharmacokinetic parameter estimation

for 43, 46, and 76 in rats were conducted using noncompartmental

methods. WinNonlin software (version 5.2.1, Pharsight Corporation,

4195

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

Chemistry. Reagents were purchased from commercial suppliers

and used without further puriﬁcation. Commercially available an-

hydrous solvents were used and stored under nitrogen unless indicated

otherwise. Reactions involving moisture sensitive reagents were con-

ducted under an atmosphere of dry nitrogen in glassware dried with a

heat gun. Thin layer chromatography (TLC) using silica gel Merck 60

F₂₅₄plates and detection with UV light was used to monitor reactions.

¹H NMR spectra were recorded in CDCl₃, CD₃OD, or DMSO-d₆

solutions on a Varian 200, Bruker 300, or Varian 400 MHz machine.

Chemical shifts are reported in parts per million (δ) downﬁeld of

tetramethylsilane (TMS). GC-MS were aquired on an Agilent 5973

network machine. LC-MS were acquired on an Applied Biosystems/

MDS Sciex API-2000 system. Flash chromatography was carried out

with silica gel (0.04−0.06 μm, 230−400 mesh), reverse phase silica gel

(C₁₈35−70 μm), or on a Flashmaster II system using cartridges

prepared in-house. Microwave irradiations were conducted using a

Biotage initiator. All compounds tested in the in vitro and in vivo

biological screens were puriﬁed to ≥95% purity as determined by

analysis of HPLC on an Agilent 1100 series machine, ﬁtted with a C₈

reverse phase Agilent zorbax eclipse DB-LB 4.6 mm × 150 mm 5 μm

column (Flow rate 1.2 mL/min. Method 1: 20% acetonitrile in water,

increasing to 60% acetonitrile over 10 min. Method 2: 50% acetonitrile

in water increasing to 90% acetonitrile over 10 min. Method 3: 70%

carbinol (0.16 mmol, 1 equiv) and glacial acetic acid (0.5 mL). To this

solution was added stannous chloride (0.274 mmol, 1.7 equiv), fol-

lowed by c hydrochloric acid (158 μL). The mixture was heated under

reﬂux for 1 h and then cooled to room temperature and left to stir

overnight. The mixture was concentrated to dryness under vacuum to

give a crude gum, which was treated with pyridine (2 mL), and the

resultant precipitate was ﬁltered and washed with tetrahydrofuran. The

ﬁltrate was concentrated under vacuum, dissolved in toluene (50 mL),

washed with 10% aqueous hydrochloric acid (10 mL) and water

(2 × 20 mL), dried over magnesium sulfate, ﬁltered, and concentrated

under vacuum.

General methods were used interchangeably for aryl and heteroaryl

analogues and have been depicted in Scheme 1 as either one or the

other for clarity. Syntheses of intermediate compounds (5−9, 13, 16,

29−31, 35−40, 47, 51, 53−54, 56, 63, 67)A[i−iii], (4−9, 13, 16−17,

29−31, 34−40, 47, 51−56, 63, 67)B[i−iii], and 77−87 are detailed

in the Supporting Information.

Synthesis of Compounds in Table 1. Bis(4-chlorophenyl)(pyrimidin-

5-yl)methanol (3). General method C (pyrimidine) with

4-chlorobenzenophenone (0.5 g, 2.3 mmol), 5-bromopyrimi-

dine (0.369 g, 2.3 mmol), tetrahydrofuran (10 mL), and n-

butyllithium (1.6 M in hexanes, 1.7 mL, 2.55 mmol). Puri-

ﬁcation by ﬂash column chromatography (eluting with 20%

ethyl acetate in hexanes increasing to 40% ethyl acetate) gave

1

acetonitrile in water increasing to 95% acetonitrile over 10 min.). H

1

NMR spectra (accounting for noncompound peaks and residual

solvent) and LC-MS. Fenarimol [60168-88-9] (1) and Pyrifenox

[88283-41-4] (2) were purchased from commercial sources.

3 as a white solid (360 mg, 53%). H NMR (300 MHz,

chloroform-d) δ 9.12 (s, 1H), 8.66 (s, 2H), 7.35 (d, J = 8.4 Hz,

4H), 7.18 (d, J = 8.4 Hz, 4H), 3.26 (s, 1H). [M + 1] 331.1.

HPLC (water/ACN + 0.1% TFA gradient) 98.80% at 230 nm.

(4-Chlorophenyl)(4-methylphenyl)pyrimidin-5-yl Methanol (4).

General method C (pyrimidine) with 4Bi (0.27 g, 1.15 mmol), 5-

bromopyrimidine (0.406 g, 1.84 mmol), dry tetrahydrofuran (10 mL),

and n-butyllithium (1.6 M in hexanes, 1.43 mL, 1.84 mmol). Puri-

ﬁcation by ﬂash column chromatography (eluting with 10% ethyl

acetate in hexanes increasing to 60% ethyl acetate), followed by

trituration with diethyl ether gave 4 as a white solid (118 mg, 33%).

¹H NMR (300 MHz, chloroform-d) δ 9.14 (s, 1H), 8.70 (s, 2H),

7.30−7.38 (m, 2H), 7.15−7.26 (m, 4H), 7.06−7.13 (m, 2H), 2.91 (s,

1H), 2.37 (s, 3H). ESI m/z: 310 (M). HPLC (water/ACN + 0.1%

TFA gradient) 95.83% at 230 nm.

Synthesis of Compounds. General Method C: Triarylcarbinol

Formation by Aryl Lithium Addition to Benzophenone. Pyrimidine.

A 50 mL three-necked round-bottom ﬂask equipped with a

low temperature thermometer, a gas adapter, and a suba seal

and was charged with the benzenophenone (1 equiv, 2.3 mmol)

and 5-bromopyrimidine (1 equiv, 2.3 mmol) dissolved in

dry tetrahydrofuran (10 mL). The reaction was cooled below

−80 °C with an ether/dry ice bath under an atmosphere

of nitrogen. To this was added portionwise via syringe

n-butyllithium (1.1 equiv of a 1.6 M solution in hexanes),

maintaining an internal temperature of −80 °C over 2.5 h. After

addition was complete, the reaction was stirred at −80 °C for

1 h and then slowly warmed to room temperature and stirred

overnight. The reaction was quenched with ammonium chloride

and extracted with ethyl acetate (2 × 50 mL), and the organic

extracts were combined, dried over magnesium sulfate, ﬁltered,

and concentrated under reduced pressure.

Pyridine. A 100 mL three-necked round-bottomed ﬂask was

charged with 3-bromopyridine (3.16 mmol, 1 equiv), and dry diethyl

ether (30 mL) was added. The solution was cooled to −78 °C, and n-

butyllithium (1.6 equiv of a 1.6 M solution in hexanes) was added and

the mixture stirred at −78 °C for 2 h. A solution of the benzophenone

(3.16 mmol, 1 equiv) in dry tetrahydrofuran (10 mL) was added

dropwise over 5 min, and the resultant mixture was stirred at low

temperature for 30 min and then allowed to warm to room tem-

perature and stirred overnight. Water (20 mL) was added and the

mixture extracted with ethyl acetate (3 × 30 mL), and the organic

extracts were combined and dried over magnesium sulfate, ﬁltered, and

concentrated under reduced pressure.

General Method D: Conversion of Aryl Bromide to Aryl Nitrile. A

10 mL round-bottomed ﬂask was charged with the aryl bromide (0.33

mmol, 1 equiv), potassium ferricyanide (K₄[Fe(CN)₆]·3H₂O) (0.66

mmol, 2 equiv), palladium(II)acetate (Pd(OAc)₂) (76 μmol, 0.2

equiv), anhydrous sodium carbonate (0.66 mmol, 2 equiv), and

anhydrous N,N-dimethylacetamide (3 mL). The mixture was heated at

130 °C under nitrogen overnight. On cooling, water (50 mL) was

added and the mixture extracted with ethyl acetate (50 mL). The

aqueous phase was back-extracted with ethyl acetate (30 mL), organic

phases combined and washed with water (2 × 50 mL) and a saturated

solution of sodium chloride (50 mL), and then dried over magnesium

sulfate, ﬁltered, and concentrated under reduced pressure.

(4-Chlorophenyl)(2-ﬂuorophenyl)pyrimidin-5-yl Methanol (5).

General method C (pyrimidine) with 5Bi (0.269 g, 1.15 mmol), 5-

bromopyrimidine (0.406 g, 1.7 mmol), dry tetrahydrofuran (10 mL),

and n-butyllithium (1.6 M in hexanes, 1.15 mL, 1.7 mmol). Purif-

ication by ﬂash column chromatography (eluting with 20% ethyl

acetate in hexanes increasing to 30% ethyl acetate) gave 5 as a white

1

solid (58 mg, 16%). H NMR (300 MHz, chloroform-d) δ 9.18 (s,

1H), 8.66 (s, 2H), 7.30−7.52 (m, 3H), 7.04−7.24 (m, 4H), 6.85 (t, J =

7.4 Hz, 1H), 3.59 (d, J = 9.4 Hz, 1H). GCMS m/z = 314. HPLC

(water/ACN + 0.1% TFA gradient) >99% at 230 nm.

(4-Chlorophenyl)(3-ﬂuorophenyl)pyrimidin-5-yl Methanol (6).

General method C (pyrimidine) with 6Bi (0.269 g, 1.15 mmol), 5-

bromopyrimidine (0.406 g, 1.7 mmol), dry tetrahydrofuran (10 mL),

and n-butyllithium (1.6 M in hexanes, 1.15 mL, 1.7 mmol).

Puriﬁcation by ﬂash column chromatography (eluting with 20%

ethyl acetate in hexanes increasing to 40% ethyl acetate) gave 6 as an

amorphous solid (46 mg, 13%). ¹H NMR (300 MHz, chloroform-d) δ

9.16 (s, 1H), 8.69 (s, 2H), 7.31−7.42 (m, 3H), 7.20 (d, J = 8.7 Hz,

2H), 6.93−7.13 (m, 3H), 3.03 (s, 1H). GCMS m/z = 314. HPLC

(water/ACN + 0.1% TFA gradient) 96.1% at 230 nm.

(4-Chlorophenyl)(4-bromophenyl)pyrimidin-5-yl Methanol (7).

General method C (pyrimidine) with 7Bi (710 mg, 2.4 mmol), 5-

bromopyrimidine (573 mg, 3.6 mmol), dry tetrahydrofuran (15 mL),

and n-butyllithium (1.6 M in hexanes, 1.95 mL, 3.12 mmol).

Puriﬁcation by ﬂash column chromatography (eluting with 50%

1

ethyl acetate in hexanes) gave 7 as a white solid (380 mg, 42%). H

NMR (300 MHz, chloroform-d) δ 9.09 (s, 1H), 8.64 (s, 2H), 7.50 (d,

J = 8.7 Hz, 2H), 7.35 (d, J = 8.7 Hz, 2H), 7.07−7.22 (m, 4H), 3.53 (s,

1H). GCMS m/z = 376. HPLC (water/ACN + 0.1% TFA gradient)

>99% at 230 nm.

General Method E: Dehydroxylation with Stannous Chloride

(SnCl₂). In a 50 mL round-bottomed ﬂask was added the triaryl

4196

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

(4-Triﬂuoromethylphenyl)(4-chlorophenyl)pyrimidin-5-yl Metha-

nol (8). General method C (pyrimidine) with 8Bii (180 mg, 0.63

mmol), 5-bromopyrimidine (201 mg, 1.26 mmol), dry tetrahydrofuran

(5 mL), and n-butyllithium (1.6 M in hexanes, 0.71 mL, 1.14 mmol).

Puriﬁcation by ﬂash column chromatography (eluting with 35% ethyl

(eluting with ethyl acetate in hexanes) gave 14 (2.17 g, 49%) as a tan

1

solid. H NMR (300 MHz, CDCl₃) δ 8.41−8.52 (m, 2H), 7.56−7.64

(m, 1H), 7.40−7.51 (m, 2H), 7.08−7.36 (m, 7H), 3.45 (s, 1H). GC/

MS (m/z = 375 [M]). HPLC (water/ACN + 0.1% TFA gradient) >

99% at 230 nm.

1

acetate in hexanes) gave 8 as a white solid (40 mg, 17%). H NMR

(4-Chlorophenyl)(4-triﬂuoromethylphenyl)pyridin-3-yl Methanol

(15). General method C (pyridine) with 8Bii (226 mg, 0.79 mmol), 3-

bromopyridine (120 mg, 0.76 mmol), dry diethyl ether (3 mL),

dry tetrahydrofuran (8 mL), and n-butyllithium (1.6 M in hexanes,

0.76 mL, 1.22 mmol). The crude material was absorbed onto silica and

puriﬁed by ﬂash chromatography (eluting with ethyl acetate in

(300 MHz, chloroform-d) δ 9.18 (s, 1H), 8.70 (s, 2H), 7.65 (d, J = 8.1

Hz, 2H), 7.33−7.48 (m, 4H), 7.18 (d, J = 8.7 Hz, 2H), 2.98 (s, 1H).

GCMS m/z = 364. HPLC (water/ACN + 0.1% TFA gradient) 94.2%

at 230 nm.

(2-Chlorophenyl)(4′-chlorophenyl)pyridin-3-yl Methanol (9).

General method C (pyridine) with 9Bi (0.79 g, 3.16 mmol), 3-

bromopyridine (0.5 g, 3.16 mmol), dry diethyl ether (30 mL), dry

tetrahydrofuran (10 mL), and n-butyllithium (1.6 M in hexanes,

2.6 mL, 3.48 mmol). The crude material was absorbed onto silica and

puriﬁed by ﬂash chromatography (eluting with 25% ethyl acetate in

hexanes increasing to 50% ethyl acetate) to give 9 as a white solid (952

1

hexanes) to give 15 (127 mg, 44%) as an oﬀ-white gum. H NMR

(300 MHz, CDCl₃) δ 8.52 (dd, J = 1.6, 4.8 Hz, 1H), 8.48 (d, J = 1.9

Hz, 1H), 7.57−7.65 (m, 3H), 7.42 (d, J = 8.2 Hz, 2H), 7.24−7.36 (m,

3H), 7.16−7.22 (m, 2H), 3.26 (s, 1H) trace EtOAc. GC/MS (m/z =

363 [M]). HPLC (water/ACN + 0.1% TFA gradient) 96.6% at 230 nm.

(2-Chlorophenyl)(4-chlorophenyl)pyridin-2-yl Methanol (16). To

a 100 mL three-necked ﬂask was added 2-bromochlorobenzene

(134 μL, 1.15 mmol) and THF (10 mL), the solution was cooled to

−78 °C, and t-butyllithium (0.72 mL, 1.15 mmol, 1.7 M in pentane)

was added slowly, dropwise over 40 min (CAUTION). Once addition

was complete, the solution was stirred at low temperature for 1 h, and

then a solution of 16B in THF (5 mL) was added over 5 min. The

resulting solution was stirred at low temperature for 30 min and then

slowly warmed to room temperature and stirred overnight. The reac-

tion was quenched with a saturated solution of ammonium chloride

(30 mL) and extracted with ethyl acetate (2 × 50 mL), and the

combined organic phases were dried over sodium sulfate, ﬁltered, and

concentrated. The crude material was absorbed onto silica gel and

puriﬁed several times by ﬂash chromatography (eluting with 10%

diethyl ether in hexanes increasing to 20% diethyl ether in hexanes)

to give 16 as a white solid (34 mg, 9%). ¹H NMR (300 MHz,

chloroform-d) δ 8.63 (s, 1H), 8.56 (s, 2H), 7.39−7.44 (m, 1H), 7.30−

7.38 (m, 4H), 7.15−7.23 (m, 1H), 6.89 (dd, J = 1.5, 7.9 Hz, 1H), 5.26

(s, 1H). [M + 1] 331. HPLC (water/ACN + 0.1% TFA gradient)

96.7% at 220 nm.

1

mg, 91%). H NMR (300 MHz, chloroform-d) δ 8.55−8.60 (m, 1H),

8.44−8.48 (m, 1H), 7.60−7.64 (m, 1H), 7.42−7.45 (m, 1H), 7.24−

7.37 (m, 4H), 7.12−7.23 (m, 3H), 6.72−6.70 (m, 1H), 4.52 (s, 1H).

HPLC (water/ACN + 0.1% TFA gradient) 97.6% at 230 nm.

Bis(4-chlorophenyl)(pyridin-3-yl) Methanol (10). General method

C (pyridine) with 4,4′-chlorobenzenophenone (1.59 g, 6.3 mmol), 3-

bromopyridine (1 g, 6.3 mmol), dry diethyl ether (20 mL), dry

tetrahydrofuran (30 mL), and n-butyllithium (1.6 M in hexanes,

4.7 mL, 6.6 mmol). The crude material was absorbed onto silica and

puriﬁed by ﬂash chromatography (eluting with 10% ethyl acetate in

hexanes increasing to 40% ethyl acetate) to give 10 as a white solid

(0.97 g, 46%). ¹H NMR (300 MHz, CDCl₃) δ 8.41 (dd, J = 1.70, 4.80

Hz, 1H), 8.38 (dd, J = 0.71, 2.40 Hz, 1H), 7.57−7.62 (m, 1H), 7.26−

7.33 (m, 3H), 7.15−7.25 (m, 6H), 4.03 (s, 1H), GCMS m/z = 329.

HPLC (water/ACN + 0.1% TFA gradient) 99.5% at 230 nm.

(4-Chlorophenyl)(4-methylphenyl)pyridin-3-yl Methanol (11).

General method C (pyridine) with 4Bi (200 mg, 0.87 mmol), 3-

bromopyridine (0.1 mL, 1 mmol), dry diethyl ether (4.3 mL), dry

tetrahydrofuran (3.5 mL), and n-butyllithium (1.6 M in hexanes,

0.65 mL, 1 mmol). The crude material was absorbed onto silica and

puriﬁed by Flashmaster II (eluting with hexanes increasing to 20%

ethyl acetate in hexanes over 33 min) to give 11 as a white glassy

(2-Chlorophenyl)(4-chlorophenyl)pyrimidin-2-yl Methanol (17).

A 100 mL three-necked ﬂask equipped with a gas inlet adapter, low

temperature thermometer, and a suba seal was dried under nitrogen

using a heat gun and then charged with 2-bromochlorobenzene

(0.44 g, 2.3 mmol) and dry THF (18 mL) and cooled to −80 °C. To

this solution was added slowly, dropwise, tert-butyllithium (1.7 mL, 2.3

mmol, 1.7 M solution in heptanes) (CAUTION) over 30 min, result-

ing in a pale-yellow solution. Once addition was complete, the reaction

mixture was stirred at −80 °C for 1 h. After this time, 17B (0.5 g, 2.3

mmol) as a suspension in THF (10 mL) was added dropwise, resulting

a dark-colored solution. Once addition was complete, the mixture was

stirred at low temperature for 1 h and slowly warmed to room

temperature and stirred overnight. A saturated solution of ammonium

chloride (100 mL) was added and the mixture extracted into EtOAc

(2 × 50 mL), and combined organic phases were dried (MgSO₄), ﬁltered,

and concentrated under vacuum. Puriﬁcation via ﬂash chromatography

(eluting with 80% ethyl acetate in hexanes) gave 17 as white solid

1

powder (84 mg, 31%). H NMR (300 MHz, chloroform-d) δ 8.37−

8.45 (m, 2H), 7.62 (td, J = 1.9, 8.1 Hz, 1H), 7.17−7.33 (m, 5H),

7.04−7.15 (m, 4H), 3.87 (s, 1H), 2.34 (s, 3H). GC/MS (m/z = 309

[M]). HPLC (method 1) 98% at 220 nm.

(4-Chlorophenyl)(2-ﬂuorophenyl)pyridin-3-yl Methanol (12).

General method C (pyridine) with 5Bi (3.4 g, 14.5 mmol), 3-

bromopyridine (3.64 g, 23.2 mmol), dry diethyl ether (40 mL), dry

tetrahydrofuran (20 mL), and n-butyllithium (1.6 M in hexanes, 14.5

mL, 23.2 mmol). The crude material was absorbed onto silica and

puriﬁed by ﬂash chromatography (eluting with 50% ethyl acetate in

1

hexanes) to give 12 as a white powder (2.01 g, 44%). H NMR (300

MHz, CDCl₃) δ 8.54 (dd, J = 1.6, 4.8 Hz, 1H), 8.48 (d, J = 2.1 Hz,

1H), 7.63 (td, J = 2.1, 8.1 Hz, 1H), 7.18−7.41 (m, 6H), 7.03−7.15 (m,

2H), 6.80 (td, J = 1.6, 8.1 Hz, 1H), 3.70 (d, J = 9.9 Hz, 1H). GC/MS

(m/z = 313 [M]). HPLC (water/ACN + 0.1% TFA gradient) 98.3%

at 230 nm.

1

(0.12 g, 16%). H NMR (300 MHz, chloroform-d) δ 8.77 (d, J = 4.7

Hz, 2H), 7.72−7.75 (m, 2H), 7.31−7.41 (m, 3H), 7.21−7.30 (m, 2H),

7.10−7.19 (m, 1H), 6.93−6.90 (m, 1H), 5.93 (s, 1H). ESI m/z: 330

(M). HPLC (water/ACN + 0.1% TFA gradient) 97.7% at 220 nm.

(2-Chlorophenyl)(4-chlorophenyl)pyridin-2-yl Methanol (18). To

a 100 mL three-necked round-bottom ﬂask equipped with gas adapter

and low temperature thermometer and dried under nitrogen using

a heat gun was added 2-bromopyridine (0.5 g, 3.16 mmol) and Et₂O

(10 mL). The mixture was cooled to −78 °C and tert-butyllithium

(1.7 mL, 3.38 mmol, 1.7 M solution in heptanes) (CAUTION) was

added slowly, dropwise. The resulting red−brown mixture was stirred at

low temperature for 1 h, and then a solution of 9Bi (0.5 g, 3.16 mmol)

in dry THF (10 mL) was added over 5 min. The reaction mixture was

stirred at −78 °C for 30 min and then slowly warmed to room tem-

perature and stirred overnight. A saturated solution of ammonium

chloride (30 mL) was added, and the mixture was extracted with EtOAc

(2 × 30 mL), dried (MgSO₄), ﬁltered, and concentrated under vacuum.

(4-Chlorophenyl)(3-ﬂuorophenyl)pyridin-3-yl Methanol (13).

General method C (pyridine) with 3-ﬂuoro bromobenzene (242 mg,

1.38 mmol), n-butyllithium (1.6 M in hexanes, 0.8 mL, 1.29 mmol),

dry diethyl ether (3 mL), 13Biii (200 mg, 0.92 mmol), and dry

tetrahydrofuran (3 mL). Puriﬁcation by ﬂash column chromatography

(eluting with 10% ethyl acetate in dichloromethane increasing to 35%

1

ethyl acetate) gave 13 as an oﬀ-white solid (193 mg, 67%). H NMR

(300 MHz, chloroform-d) δ 8.38−8.52 (m, 2H), 7.57−7.66 (m, 1H),

7.15−7.37 (m, 6H), 6.94−7.06 (m, 3H), 3.61 (s, 1H). GCMS m/z

313. HPLC (method 1) 96.1% at 220 nm.

(4-Bromophenyl)(4-chlorophenyl)pyridin-3-yl Methanol (14).

General method C (pyridine) with 7Bi (3.5 g, 11.8 mmol),

n-butyllithium (1.6 molar solution in hexanes, 7.7 mL, 12.3 mmol),

3-bromopyridine (1.3 mL, 13 mmol), diethyl ether (50 mL), and

tetrahydrofuran (35 mL). Puriﬁcation by ﬂash column chromatography

4197

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

Puriﬁcation by ﬂash chromatography (eluting with 5% EtOAc in

hexanes increasing to 20% EtOAc) gave 18 as white solid (340 mg,

32%). H NMR (300 MHz, DMSO-d₆) δ 8.64 (br s, 1H), 8.16 (br s,

1H), 7.74 (d, J = 7.7 Hz, 1H), 7.63 (br s, 1H), 7.46 (s, 5H), 7.26−7.43

(m, 2H), 6.98 (d, J = 7.5 Hz, 1H). ESI m/z: 329 (M). HPLC (water/

ACN + 0.1% TFA gradient) 97.7% at 220 nm.

extracted with ethyl acetate (3 × 30 mL). The organic phases were

combined, washed with water (50 mL), dried over sodium carbonate,

ﬁltered, and concentrated under vacuum. Puriﬁcation by Flashmaster

II (10 g column, eluting with 20% ethyl acetate in hexanes increasing

to 100% ethyl acetate over 22 min) gave 22 as a yellow oil (115 mg,

24%). ¹H NMR (300 MHz, chloroform-d) δ 8.49−8.58 (m, 1H), 7.60

(td, J = 1.98, 8.10 Hz, 1H), 7.41 (dd, J = 1.40, 7.82 Hz, 1H), 7.19−

7.35 (m, 6H), 7.13 (dt, J = 1.41, 7.58 Hz, 1H), 6.79 (dd, J = 1.70, 7.91

Hz, 1H), 2.84 (br s, 2H). GC/MS (m/z = 328 [M]). HPLC (water/

ACN + 0.1% TFA gradient) 95.4% at 220 nm.

1

(2-Chlorophenyl)(4-chlorophenyl)(pyrimidin-4-yl)methanol (19).

A 50 mL three-necked ﬂask equipped with a suba seal, gas adapter, and

low temperature thermometer and dried under nitrogen with a heat

gun was charged with dry THF (10 mL) and tetramethylpiperidine

(TMP) (0.24 g, 1.72 mmol). The mixture was cooled to −78 °C and

n-butyllithium (1.15 mL, 1.72 mmol, 1.6 M solution in hexanes) was

added dropwise over 10 min. The mixture was stirred for 30 min

at −78 °C, warmed to 0 °C, and then cooled back down to −78 °C. A

solution of 9Bi (288 mg, 1.15 mmol) and pyrimidine (138 mg, 1.72

mmol) in dry THF (5 mL) was added dropwise, keeping the

temperature below −60 °C. Once addition was complete (30 min),

the mixture was stirred at low temperature for 1 h, warmed to room

temperature, and stirred overnight. A saturated solution of ammonium

chloride (30 mL) was added, and the mixture was extracted with ethyl

acetate (2 × 30 mL), dried over magnesium sulfate, ﬁltered, and con-

centrated under vacuum. Puriﬁcation by ﬂash chromatography (eluting

with 50% ethyl acetate in hexanes), followed by trituration of the

puriﬁed material with diethyl ether, gave 19 as white solid (25 mg,

6.5%). ¹H NMR (300 MHz, chloroform-d) δ 9.22 (s, 1H), 8.78−8.66

(m, 1H), 7.28 −7.49 (m, 8H), 7.12−7.21 (m, 1H), 6.83−6.92 (m,1H),

5.35 (s, 1H). ESI m/z: 330 (M). HPLC (water/ACN + 0.1% TFA

gradient) 97.7% at 220 nm.

N-((2-Chlorophenyl)(4-chlorophenyl)(pyridin-3-ylmethyl)-2-

methylpropan-1-amine (23). A ﬂask was charged with 76 (200 mg,

0.57 mmol), isobutyl amine (0.2 mL, 1.15 mmol), and N,N-

dimethylformamide (12 mL) and the mixture stirred for 72 h at

room temperature and then poured onto water (30 mL) and extracted

with ethyl acetate (2 × 30 mL). The organic phases were combined,

washed with brine (20 mL), dried over sodium carbonate, ﬁltered, and

concentrated. Puriﬁcation by Flashmaster II to give 23 as a pale-yellow

1

oil (47 mg, 22%). H NMR (300 MHz, chloroform-d) δ 8.72 (br s,

1H), 8.42 (dd, J = 1.5, 4.7 Hz, 1H), 7.72−7.81 (m, 1H), 7.41 (dd, J =

1.80, 6.80 Hz, 4H), 7.15−7.33 (m, 5H), 2.49−2.57 (m, 1H), 1.76−

1.94 (m, 3H), 0.94 (d, J = 5.8 Hz, 6H). GC/MS (m/z = 384 [M]).

HPLC (water/ACN + 0.1% TFA gradient) 96.3% at 220 nm.

5-[(2-Chlorophenyl)(4-chlorophenyl)methyl]pyrimidine (24).

General method E with 1 (50 mg, 0.16 mmol), tin(II)chloride (52

mg, 0.274 mmol), c. hydrochloric acid (158 μL) and glacial acetic acid

(500 μL). Puriﬁcation by ﬂash chromatography (eluting with 50%

1

ethyl acetate in toluene) gave 24 (30 mg, 26%) as a yellow gum. H

NMR (300 MHz, chloroform-d) δ 9.13 (s, 1H), 8.46 (s, 2H), 7.38−

7.50 (m, 1H), 7.18−7.37 (m, 4H), 7.01 (d, J = 8.3 Hz, 2H), 6.84−6.94

(m, 1H), 5.92 (s, 1H). [M + 1] 315. HPLC (water/ACN + 0.1% TFA

gradient) 99.1% at 220 nm.

Synthesis of Compounds in Table 2. 3-[Methoxy(2-chloro-

phenyl)(4-chlorophenyl)methyl]pyridine (20). A dry 25 mL round-

bottomed ﬂask was charged with methanol (8 mL) and sodium

(200 mg) added portionwise under a nitrogen atmo-

sphere. The mixture was stirred until bubbling had ceased,

and then 76 (280 mg) was added and the mixture stirred for

48 h at room temperature. The mixture was concentrated under

vacuum and the crude residue taken up in dichloromethane

(30 mL) and washed with water (30 mL). The aqueous phase

was back-extracted with water (2 × 20 mL), and the organic

phases were combined, dried over sodium carbonate, ﬁltered,

and concentrated under vacuum. Puriﬁcation by Flashmaster

II (2 g column, eluting with 100% hexanes increasing to 25%

ethyl acetate in hexanes over 22 min) gave 20 as a yellow glass

(96 mg, 43%). ¹H NMR (300 MHz, chloroform-d) δ 8.69 (br s,

1H), 8.50 (br d, J = 3.5 Hz, 1H), 7.71−7.85 (m, 2H), 7.20−

7.43 (m, 8H), 3.07 (s, 3H). GC/MS (m/z = 343 [M]). HPLC

(water/ACN + 0.1% TFA gradient) >99% at 220 nm.

(2-Chlorophenyl)(4-chlorophenyl)(pyridin-3-yl)acetonitrile (21).

A 100 mL round-bottomed ﬂask was charged with 76 (1.2 g, 3 mmol)

and N,N-dimethylformamide (15 mL). Sodium cyanide (180 mg,

3.6 mmol) (CAUTION) was added and the reaction stirred at room

temperature for 30 min and then heated at 90 °C overnight. On

cooling, the mixture was poured onto water (200 mL), more water

(100 mL) added, and then dichloromethane (100 mL). The layers

were separated, the aqueous phase back-extracted with dichloro-

methane (4 × 50 mL), and the combined organic phases were washed

with water (2 × 50 mL), dried over sodium carbonate, ﬁltered, and

concentrated under vacuum. Further washing with brine was required

to remove traces of N,N-dimethylformamide. Puriﬁcation by Flash-

master II (2 g column, eluting with 100% hexanes increasing to 30%

ethyl acetate in hexanes over 30 min) gave 21 as sticky glass (120 mg,

12%). ¹H NMR (300 MHz, chloroform-d) δ 8.65 (dd, J = 1.5, 4.7 Hz,

1H), 8.44 (dd, J = 0.6, 2.5 Hz, 1H), 7.63 (dt, J = 2.0, 8.1 Hz, 1H), 7.51

(dd, J = 1.3, 7.9 Hz, 1H), 7.33−7.43 (m, 4H), 7.15−7.25 (m, 3H),

6.61 (dd, J = 1.5, 7.9 Hz, 1H), 3% EtOAc. GC/MS (m/z = 338 [M]).

HPLC (water/ACN + 0.1% TFA gradient) 96.5% at 220 nm.

(2-Chlorophenyl)(4-chlorophenyl)(pyridin-3-yl)methanamine

(22). A 50 mL round-bottomed ﬂask was charged with 76 (500 mg,

1.43 mmol), N,N-dimethylformamide (5 mL), and ammonia in meth-

anol (1 mL, 7 mmol of a 7 M solution). The reaction was stirred

at room temperature overnight, poured into water (150 mL), and

5-[(2-Chlorophenyl)(4-chlorophenyl)methyl]pyrimidine (25).

General method E with 3 (113 mg, 0.35 mmol), tin(II)chloride

(125 mg, 0.595 mmol), c hydrochloric acid (352 μL), and glacial acetic

acid (1.1 mL) except compound obtained by precipitation from

pyridine solution on addition of toluene to give 25 (64 mg, 55%) as a

1

yellow gum. H NMR (300 MHz, chloroform-d) δ 9.13 (s, 1H), 8.48

(s, 2H), 7.32 (d, J = 8.3 Hz, 4H), 7.02 (d, J = 8.3 Hz, 4H), 5.47 (s,

1H). ESI m/z: 314 (M). HPLC (water/ACN + 0.1% TFA gradient)

99.9% at 220 nm.

3-((2-Chlorophenyl)(4-chlorophenyl)methyl)pyridine (26). Gener-

al method E with 9 (200 mg, 0.6 mmol), tin(II)chloride (270 mg, 1.2

mmol), c hydrochloric acid (2 mL), and glacial acetic acid (5 mL).

Puriﬁcation by Flashmaster II (eluting with ethyl acetate in hexanes)

gave 26 as a yellow oil (75 mg, 40%). ¹H NMR (300 MHz, chloroform-d)

δ 8.51 (br d, J = 3.9 Hz, 1H), 8.38 (br s, 1H), 7.37−7.45 (m, 1H),

7.17−7.37 (m, 6H), 7.00 (br d, J = 8.5 Hz, 2H), 6.85−6.92 (m, 1H),

5.94 (s, 1H). GC/MS (m/z = 313 [M]). HPLC (water/ACN + 0.1%

TFA gradient) 99.3% at 220 nm.

3-(Bis(4-chlorophenyl)methyl)pyridine (27). General method E

with 10 (57 mg, 0.17 mmol), tin(II)chloride (56 mg, 0.29 mmol), c

hydrochloric acid (2 mL), and glacial acetic acid (5 mL). Reaction

mixture heated under reﬂux for 18 h, with additional tin(II)chloride

(140 mg, 0.74 mmol) added after 4 h. Puriﬁcation by ﬂash column

chromatography (eluting with ethyl acetate in hexanes) gave 27 as a

1

pale-yellow oil (9 mg, 17%). H NMR (300 MHz, CDCl₃) δ 8.32−

8.73 (m, 2H), 7.65 (br d, J = 7.7 Hz, 1H), 7.50 (br s, 1H), 7.28−7.37

(m, 4H), 6.95−7.08 (m, 4H), 5.57 (s, 1H). GC/MS (m/z = 313 [M]).

HPLC (water/ACN + 0.1% TFA gradient) 99.3% at 220 nm.

(4-Chlorophenyl)(2-chlorophenyl)pyrimidin-5-yl N-Oxide Metha-

nol (28). 1 (25 mg, 0.025 mmol) was dissolved in dichloromethane

(2 mL) and the solution cooled in an ice-bath. meta-Chloroperbenzoic

(77%, 34 mg, 0.15 mmol) was added and the reaction stirred for 48 h

under an atmosphere of nitrogen. Water (10 mL) and dichloro-

methane (10 mL) were added, and the aqueous phase was separated

and back-extracted with dichloromethane (2 × 10 mL). The organic

phases were combined and washed with brine (10 mL), dried over

sodium sulfate, ﬁltered, concentrated, and solvent removed under re-

duced pressure. Puriﬁcation by ﬂash column chromatography (eluting

4198

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

with 30% ethyl acetate in hexanes increasing to 100% ethyl acetate)

gave 28 (13 mg, 50%) as a white powder. ¹H NMR (300 MHz,

chloroform-d) δ 8.92 (s, 1H), 8.32 (s, 1H), 8.10 (s, 1H), 7.43−7.54

(m, 1H), 7.32−7.43 (m, 3H), 7.15−7.32 (m, 3H), 6.78 (dd, J = 1.2,

7.8 Hz, 1H), 4.53 (br s, 1H). HPLC (method 2) 97.9% at 220 nm.

Synthesis of Compounds in Table 3. (4-Chlorophenyl)(2-methyl-

phenyl)pyridin-3-yl Methanol (29). General method C (pyridine)

with 29Bii (260 mg, 1.15 mmol), 3-bromopyridine (400 mg,

1.84 mmol), dry diethyl ether (6 mL), dry tetrahydrofuran (4

mL), and n-butyllithium (1.6 M in hexanes, 1.43 mL, 1.84

mmol). The crude material was absorbed onto silica and

puriﬁed by ﬂash column chromatography (eluting with 20%

ethyl acetate in hexanes increasing to 40%). The material was

further puriﬁed by reverse phase silica column chromatography

(eluting with 40% methanol in water increasing to 60%). The

solvent was removed under reduced pressure and the residue

re-extracted into dichloromethane, washed with water, dried

over magnesium sulfate, ﬁltered, and concentrated to give 29 as

a cream solid (280 mg, 79%). ¹H NMR (300 MHz, chloroform-d)

δ 8.42−8.62 (m, 2H), 7.57 (td, J = 1.84, 8.01 Hz, 1H),

7.28−7.36 (m, 2H), 7.16−7.25 (m, 4H), 7.00−7.11 (m, 1H),

6.69 (d, J = 7.91 Hz, 1H), 3.34 (br s, 1H), 2.12 (s, 3H). GCMS

m/z = 309. HPLC (water/ACN + 0.1% TFA gradient) 90% at

254 nm.

6.70−6.75 (m, 1H), 4.47 (spt, J = 6.1 Hz, 1H), 3.38 (s, 1H), 1.28 (d,

J = 6.1 Hz, 7H). GC/MS (m/z = 353 [M]). HPLC (water/ACN +

0.1% TFA gradient) 95.6% at 220 nm.

(4-Chlorophenyl)(4-isopropoxyphenyl)pyridin-3-yl Methanol

(34). General method C (pyridine) with 3-bromopyridine (0.1 mL,

1 mmol), n-butyllithium (1.6 M in hexanes, 0.62 mL, 0.93 mmol),

dry diethyl ether (5 mL), 34Bii (187 mg, 0.68 mmol), and dry

tetrahydrofuran (8 mL). Puriﬁcation by ﬂash column chromatography

(eluting with 30% ethyl acetate in hexanes) gave 34 (40 mg, 17%) as a

white solid. ¹H NMR (300 MHz, chloroform-d) δ 8.44−8.58 (m, 2H),

7.66 (d, J = 7.9 Hz, 1H), 7.19−7.37 (m, 4H), 7.09−7.11 (m, 2H),

6.85−6.82 (m, 2H), 4.56 (spt, J = 6.1 Hz, 1H), 3.16 (s, 1H), 1.35 (d,

J = 6.1 Hz, 6H), 3.16 (s, 1H). GCMS m/z = 353. HPLC (water/

AcCN + 0.1% TFA gradient) 98.5% at 220 nm.

(4-Triﬂuoromethylphenyl)(4-isopropoxyphenyl)pyridin-3-yl

Methanol (35). General method C with 4-bromobenzotriﬂuoride

(279 mg, 1.24 mmol), n-butyllithium (1.6 M in hexanes, 1.16 mL, 1.25

mmol), dry diethyl ether (3 mL), 35Biii (200 mg, 0.83 mmol), and

dry tetrahydrofuran (3 mL). Puriﬁcation by ﬂash column chromatog-

raphy (eluting with 5% ethyl acetate in dichloromethane increasing to

40% ethyl acetate) gave 35 as a pale-yellow semisolid (140 mg, 44%).

¹H NMR (300 MHz, CDCl₃) δ 8.48−8.59 (m, 2H), 7.54−7.62 (m,

1H), 7.59 (d, J = 8.7 Hz, 1H), 7.41−7.50 (m, 1H), 7.22−7.31 (m,

1H), 7.08 (d, J = 8.7 Hz, 1H), 6.84 (d, J = 8.7 Hz, 5H), 4.55 (spt, J =

6.1,Hz, 1H), 2.95 (br s, 1H), 1.34 (d, J = 6.1 Hz, 6H). HPLC (method

1) 97.2% at 220 nm.

(4-Chlorophenyl)(3-methoxyphenyl)pyridin-3-yl Methanol (30).

General method C (pyridine) with 4-bromochlorobenzene (243 mg,

1.27 mmol), n-butyllithium (1.6 M in hexanes, 1.18 mL, 1.4 mmol),

dry diethyl ether (3 mL), 30Biii (180 mg, 0.84 mmol), and dry

tetrahydrofuran (3 mL). Puriﬁcation by ﬂash column chromatography

(eluting with 10% ethyl acetate in dichloromethane increasing to 35%

(4-Chlorophenyl)(2-bromophenyl)pyridin-3-yl Methanol (36).

General method C (pyridine) with 3-bromopyridine (991 mg, 6.31

mmol), n-butyllithium (1.6 M in hexanes, 3.94 mL, 6.31 mmol), dry

diethyl ether (15 mL), 36 Bi (1.16 g, 3.95 mmol), and dry

tetrahydrofuran (15 mL). Puriﬁcation by Flashmaster II (10 g column,

eluting with 20% ethyl acetate in hexanes over 44 min at 5 mL/min)

1

ethyl acetate) gave 30 as an oﬀ-white gum (63 mg, 23%). H NMR

(300 MHz, chloroform-d) δ 8.43−8.55 (m, 2H), 7.58−7.67 (m, 1H),

7.16−7.37 (m, 6H), 6.70−6.93 (m, 3H), 3.75 (s, 3H), 3.29 (s, 1H).

GCMS m/z 325. HPLC (water/ACN + 0.1% TFA gradient) 99.2% at

220 nm.

1

gave 36 as an oﬀ-white solid (570 mg, 39%). H NMR (300 MHz,

chloroform-d) δ 8.38−8.53 (m, 2H), 7.57−7.64 (m, 1H), 7.40−7.51

(m, 2H), 7.28−7.35 (m, 2H), 7.09−7.24 (m, 4H), 3.56 (br s, 1H).

GCMS m/z = 375. HPLC (water/ACN + 0.1% TFA gradient) 99% at

220 nm.

(4-Chlorophenyl)(4-methoxyphenyl)pyridin-3-yl Methanol (31).

General method C (pyridine) with 3-bromopyridine (0.2 mL, 2

mmol), n-butyllithium (1.6 M in hexanes, 1.5 mL, 2.25 mmol), dry

diethyl ether (10 mL), 31Bi (420 mg, 1.7 mmol), and dry

tetrahydrofuran (10 mL). Puriﬁcation by Flashmaster II (eluting

with 20% ethyl acetate in hexanes increasing to 40% ethyl acetate)

(4-Chlorophenyl)(3-bromophenyl)pyrid-3-yl Methanol (37). Gen-

eral method C (pyridine) with 37 Bi (1 g, 3.38 mmol), 3-bromopyridine

(850 mg, 5.41 mmol), dry diethyl ether (10 mL), dry tetrahydrofuran

(5 mL), and n-butyllithium (1.6 M in hexanes, 3.38 mL, 5.41 mmol).

The crude material was absorbed onto silica and puriﬁed by ﬂash

chromatography (50% ethyl acetate in hexanes) to give 37 as a white

1

gave 31 as a pale-yellow glass (950 mg, 35%). H NMR (300 MHz,

CDCl₃) δ 8.42−8.49 (m, 2H), 7.59−7.66 (m, 1H), 7.18−7.32 (m,

5H), 7.07−7.15 (m, 2H), 6.81−6.88 (m, 2H), 3.80 (s, 3H), 3.47 (br s,

1H). GC/MS (m/z = 325 [M]). HPLC (water/ACN + 0.1% TFA

gradient) 95.5% at 220 nm.

1

powder (410 mg, 32%). H NMR (300 MHz, chloroform-d) δ 8.46−

8.58 (m, 1H), 7.58−7.65 (m, 1H), 7.41−7.50 (m, 2H), 7.29−7.36 (m,

3H), 7.09−7.23 (m, 5H), 2.98 (s, 1H). GCMS m/z = 375. HPLC

(method 1) 98.8% at 220 nm.

(4-Chlorophenyl)(2-(propan-2-yloxy)phenyl)pyridin-3-yl Metha-

nol (32). General method C (pyridine) with 77 (0.5 g, 2.3 mmol),

n-butyllithium (1.6 M in hexanes, 1.3 mL, 2 mmol), dry diethyl ether

(5 mL), 13Biii (340 mg, 1.55 mmol), and dry tetrahydrofuran (5 mL).

Puriﬁcation in the ﬁrst instance by ﬂash column chromatography

(eluting with 20% ethyl acetate in hexanes) and then by reverse phase

silica column chromatography (eluting with 60% methanol in water)

(4-Triﬂuoromethylphenyl)(4-bromophenyl)pyrid-3-yl Methanol

(38). General method C with 4-bromobenzotriﬂuoride (773 mg,

3.44 mmol), dry diethyl ether (6 mL), n-butyllithium (1.6eq of a 1.6 M

solution in hexanes, 2.0 mL, 3.21 mmol), 38Biii (600 mg, 2.29 mmol),

and dry tetrahydrofuran (6 mL). Puriﬁcation by ﬂash column chroma-

tography (eluting with 5% ethyl acetate in dichloromethane, increasing

to 33% ethyl acetate) gave 38 as an oﬀ white solid (815 mg, 87%). ¹H

NMR (300 MHz, chloroform-d) δ 8.40−8.54 (m, 2H), 7.57−7.68 (m,

3H), 7.48 (d, J = 8.5 Hz, 2H), 7.42 (d, J = 8.2 Hz, 2H), 7.21−7.32 (m,

1H), 7.13 (d, J = 8.5 Hz, 2H), 3.53 (s, 1H). GCMS m/z 407/409.

HPLC (method 1) 99.8% at 220 nm.

(4-Chlorophenyl)(2-triﬂuoromethylphenyl)pyridin-3-yl methanol

(39). General method C (pyridine) with 3-bromopyridine (0.23 mL,

2.3 mmol), dry diethyl ether (10 mL), n-butyllithium (1.4 mL, 2.3

mmol, 1.6 M solution in hexanes), and 39Bii (160 mg, 0.56 mmol) in

dry tetrahydrofuran (5 mL). The crude material was absorbed onto

silica gel and puriﬁed by ﬂash column chromatography (eluting with

25% ethyl acetate in hexanes) to give 39 as a white solid (240 mg, 84%).

¹H NMR (300 MHz, CDCl₃) δ 8.52 (dd, J = 1.6, 4.8 Hz, 1H), 8.48 (d,

1

gave 32 as a pale-yellow gum (250 mg, 45%). H NMR (300 MHz,

CDCl₃) δ 8.53 (dd, J = 1.6, 4.8 Hz, 1H), 8.44 (dd, J = 0.8, 2.4 Hz, 1H),

7.58−7.67 (m, 1H), 7.18−7.33 (m, 6H), 6.93 (d, J = 8.0 Hz, 1H), 6.81

(dt, J = 1.1, 7.6 Hz, 1H), 6.50 (dd, J = 1.7, 7.6 Hz, 1H), 5.45 (s, 1H),

4.54 (spt, J = 6.0 Hz, 1H), 1.03 (d, J = 6.0 Hz, 3H), 1.00 (d, J = 6.0 Hz,

3H). GC/MS (m/z = 353 [M]). HPLC (water/ACN + 0.1% TFA

gradient) 98.3% at 220 nm.

(4-Chlorophenyl)(3-(propan-2-yloxy)phenyl)pyridin-3-yl Metha-

nol (33). General method C (pyridine) with 78 (0.5 g, 2.3 mmol),

n-butyllithium (1.6 M in hexanes, 1.3 mL, 2 mmol), dry diethyl ether

(5 mL), 13Biii (340 mg, 1.55 mmol), and dry tetrahydrofuran (5 mL).

Puriﬁcation in the ﬁrst instance by ﬂash column chromatography

(eluting with 20% ethyl acetate in hexanes) and then by reverse phase

silica column chromatography (eluting with 60% methanol in water)

1

J = 1.9 Hz, 1H), 7.57−7.65 (m, 3H), 7.42 (d, J = 8.2 Hz, 2H), 7.24−7.36

(m, 3H), 7.16−7.22 (m, 2H), 3.26 (s, 1H). GC/MS (m/z = 363 [M]).

HPLC (water/ACN + 0.1% TFA gradient) 99.1% at 220 nm.

gave 33 as a white powder (300 mg, 54%). H NMR (300 MHz,

chloroform-d) δ 8.44−8.52 (m, 2H), 7.63 (ddd, J = 1.9 × 2, 8.3 Hz,

1H), 7.18−7.33 (m, 6H), 6.80−6.85 (m, 1H), 6.76 (t, J = 2.1 Hz, 1H),

4199

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

(4-Chlorophenyl)(3-triﬂuoromethylphenyl)pyridin-3-yl Methanol

(40). General method C (pyridine) with 3-bromopyridine (0.15 mL,

1.5 mmol), dry diethyl ether (5 mL), n-butyllithium (0.96 mL, 1.4

mmol, 1.6 M solution in hexanes), and 40Bii (280 mg, 0.98 mmol) in

dry tetrahydrofuran (3.5 mL). The crude material was absorbed onto

silica gel and puriﬁed by ﬂash column chromatography (eluting with

20% ethyl acetate in hexanes) to give 40 as a pale-yellow gum (58 mg,

3-[(4-Chlorophenyl)(hydroxy)pyridin-3-ylmethyl]benzamide (46).

41 (2.3 g, 7.17 mmol) was hydrolyzed by KOH (1.93 g, 34.4 mmol) in

t-BuOH (20 mL) on heating under reﬂux for 45 min. The mixture was

cooled, concentrated to half volume under reduced pressure, and then

partitioned between ethyl acetate (100 mL) and dilute HCl (100 mL

to pH7). The organic phase was washed with water (100 mL), brine

(100 mL), separated, dried (MgSO₄), ﬁltered, and concentrated under

reduced pressure. Puriﬁcation by column chromatography (eluent

100% DCM, 50% DCM in EtOAc, 5% 7 M NH₃in MeOH in EtOAc),

followed by trituration with 10% DCM in Et₂O, ﬁltration, and washing

1

16%). H NMR (300 MHz, CDCl₃) δ 8.40−8.52 (m, 2H), 7.65 (s,

1H), 7.55−7.63 (m, 2H), 7.37−7.49 (m, 2H), 7.23−7.35 (m, 4H),

7.15−7.21 (m, 2H), 3.68 (s, 1H). GC/MS (m/z = 363 [M]). HPLC

(water/ACN + 0.1% TFA gradient) 97.7% at 220 nm.

1

with Et₂O gave 46 as a white powder (1.84 g, 76%). H NMR (300

MHz, CDCl₃) δ 8.24 (dd, J = 0.1, 1.8 Hz, 1H), 8.18 (dd, J = 1.2, 4.7

Hz, 1H), 7.88 (br s, 1H), 7.55−7.61 (m, 1H), 7.45−7.54 (m, 1H),

7.03−7.29 (m, 6H), 6.92 (br s, 1H), 6.45 (br s, 1H). ESI [M + H] =

339.4. HPLC (water/ACN + 0.1% TFA gradient) 99.5% at 220 nm.

3-[(4-Chloro-2-ﬂuorophenyl)(hydroxy)pyridin-3-ylmethyl]-

benzamide (47). Method as for 46 with 83 (337 mg, 1 mmol), t-

BuOH (13.2 mL), and KOH (0.4 g, 7 mmol). Heated under reﬂux for 2 h.

3-[(4-Chlorophenyl)(hydroxy)pyridin-3-yl methyl]benzonitrile

(41). General method D with 37 (123 mg, 0.33 mmol), potassium

ferricyanide (280 mg, 0.66 mmol), palladium(II)acetate (17 mg, 76 μmol),

sodium carbonate (70 mg, 0.66 mmol), and N,N-dimethylacetamide

(3 mL). The crude material was absorbed onto silica and puriﬁed by

ﬂash chromatography (eluting with 30% ethyl acetate in hexanes) to

give 41 as a white powder (70 mg, 67%). ¹H NMR (300 MHz, CDCl₃)

δ 8.37−8.51 (m, 2H), 7.56−7.67 (m, 3H), 7.41−7.55 (m, 2H), 7.27−

7.37 (m, 3H), 7.12−7.21 (m, 2H), 4.03 (br s, 1H). GC/MS (m/z = 320

[M]). HPLC (method 1) 98.8% at 220 nm.

1

Usual work up gave 47 as a white powder (60.3 mg, %). H NMR (400

MHz, DMSO-d₆) δ 8.50 (br s, 2H), 7.89−8.07 (m, 1H), 7.74−7.87 (m,

2H), 7.62 (d, J = 7.43 Hz, 1H), 7.20−7.53 (m, 6H), 6.88−7.01 (m, 1H), 3.33

(br s, 1H). ESI [M + H] = 357.3. HPLC (method 1) 95.64% at 220 nm.

3-[(4-(Triﬂuoromethyl)phenyl(hydroxy)pyridin-3-ylmethyl]-

benzamide (48). Method as for 46 with 85 (876 mg, 2.47 mmol),

t-BuOH (45 mL), and KOH (1.2 g, 21 mmol). Heated under reﬂux for

4-((4-Chlorophenyl)(hydroxy)pyridin-3-ylmethyl)benzonitrile

(42). General method D with 14 (232 mg, 0.61 mmol), potassium

ferricyanide (535 mg, 1.3 mmol), palladium(II)acetate (18 mg,

80 μmol), sodium carbonate (66 mg, 0.63 mmol), and N,N-

dimethylacetamide (5 mL). The crude material was absorbed onto

silica and puriﬁed by ﬂash chromatography (eluting with 30% ethyl

1

2 h. Usual work up gave 48 as a cream powder (278 mg, 51%). H

NMR (400 MHz, chloroform-d) δ 8.14−8.46 (m, 2H), 7.89 (s, 1H),

7.28−7.72 (m, 7H), 7.01−7.25 (m, 2H), 6.47 (br s, 2H). ESI [M + H] =

373.2. HPLC (method 1) 97.28% at 220 nm.

1

acetate in hexanes) to give 42 as a cream powder (31 mg, 16%). H

NMR (300 MHz, CDCl₃) δ 8.41 (s, 2H), 7.53−7.71 (m, 4H), 7.40−

7.49 (m, 2H), 7.22−7.36 (m, 3H), 7.09−7.20 (m, 1H), 4.21 (br s,

1H). GC/MS (m/z = 320 [M]). HPLC (water/ACN + 0.1% TFA

gradient) 99.5% at 220 nm.

4-[4-(Triﬂuoromethyl)phenyl(hydroxy)pyridin-3-ylmethyl]-

benzamide (49). 43 was hydrolyzed as described for the preparation

1

of 46 to give 49 as a white powder (15 mg, 28%). H NMR (300

MHz, CDCl₃) δ 8.51 (br s, 2H), 7.82 (d, J = 8.4 Hz, 2H), 7.53−7.70

(m, 3H), 7.34−7.50 (m, 4H), 7.23−7.32 (m, 1H), 6.90 (br s, 1H),

6.17 (br s, 1H), 6.01−6.12 (m, 1H). ESI [M + H] = 373.3. HPLC

(method 1) 95.1% at 220 nm.

N-(4-((4-Chlorophenyl)(hydroxy)(pyridin-3-yl)methyl)phenyl)-

methanesulfonamide (50). Prepared according to Yin and

Buchwald²⁷from 14 to give 50 as an oﬀ-white solid (15.4 mg, 6%).

¹H NMR (300 MHz, chloroform-d) δ 8.45−8.58 (m, 2H), 7.60−7.67

4-((4-Triﬂuoromethylphenyl)(hydroxy)pyridin-3-ylmethyl)-

benzonitrile (43). General method D with 38 (1.5 g, 3.66 mmol),

potassium ferricyanide (3.27 g, 7.74 mmol), palladium(II)acetate

(495 mg, 0.72 mmol), sodium carbonate (435 mg, 4.05 mmol), and

N,N-dimethylacetamide (15 mL). The crude material was absorbed

onto silica and puriﬁed by ﬂash chromatography (eluting with

dichloromethane increasing to 50% ethyl acetate in dichloromethane)

1

to give 43 as an oﬀ-white glass (930 mg, 72%). H NMR (300 MHz,

(m, 1H), 7.29−7.36 (m, 2H), 7.14−7.25 (m, 6H), 6.52 (s, 1H), 3.05

(s, 3H), 2.93 (s, 1H). [M + 1] 389. HPLC (water/ACN + 0.1% TFA

gradient) >99% at 220 nm.

chloroform-d) δ 8.42−8.55 (m, 2H), 7.56−7.67 (m, 5H), 7.38−7.46

(m, 4H), 7.24−7.32 (m, 1H), 3.63 (s, 1H). GCMS m/z 354. HPLC

(water/ACN + 0.1% TFA gradient) 97.2% at 220 nm.

(4-Triﬂuoromethylphenyl)(4-dimethylaminophenyl)pyrid-3-yl)

Methanol (51). General method C (pyridine) with 4-bromo benzotri-

ﬂuoride (298 mg, 132 mmol), dry diethyl ether (3 L), n-butyllithium

(1.6 equiv of a 1.6 M solution in hexanes, 0.77 mL, 1.24 mmol), 51Biii

(200 mg, 0.88 mmol), and dry tetrahydrofuran (3 mL). Puriﬁcation by

ﬂash column chromatography (eluting with 10% ethyl acetate in

dichloromethane, increasing to 40% ethyl acetate) gave 51 as an oﬀ-

2-Fluoro-4-{hydroxy(pyridin-3-yl)[4-(triﬂuoromethyl)phenyl]-

methyl}benzonitrile (44). General method D with aryl bromide 81

(0.25 g, 0.604 mmol), potassium ferricyanide (K₄[Fe(CN)₆]·3H₂O)

(0.53 g, 1.27 mmol), palladium(II)acetate (38 mg), anhydrous sodium

carbonate (0.071 g, 0.66 mmol), and anhydrous N,N-dimethylaceta-

mide (3 mL). The crude material was puriﬁed by Flashmaster II

(eluting with hexanes increasing to 40% ethyl acetate over 35 min) to

give a semipuriﬁed oil which was taken up in diethyl ether and washed

with water, organic phases combined, dried over magnesium sulfate,

ﬁltered, and concentrated to remove residual N,N-dimethylacetamide,

and then triturated with diethyl ether to give 44 (60 mg, 27%) as a

1

white solid (240 mg, 73%). H NMR (300 MHz, chloroform-d) δ

8.45−8.59 (m, 2H), 7.63−7.70 (m, 1H), 7.58 (d, J = 8.4 Hz, 2H), 7.47

(d, J = 8.4 Hz, 2H), 7.20−7.31 (m, 1H), 7.01 (d, J = 6.9 Hz, 2H), 6.65

(d, J = 6.9 Hz, 2H), 3.01 (s, 1H), 2.96 (s, 6H). GCMS m/z 372.

HPLC (method 1) 99% at 220 nm.

1

white solid. H NMR (400 MHz, DMSO-d₆) δ 8.52−8.55(m, 1H),

4-(Triﬂuoromethyl)phenyl(4-(propan-2-yl)phenyl)pyridin-3-yl

Methanol (52). General method C (pyridine) with 3-bromopyridine

(0.13 mL, 1.3 mmol), dry diethyl ether (5 mL), n-butyllithium (0.77

mL, 1.23 mmol, 1.6 M solution in hexanes), and 52Bii (300 mg, 1.03

mmol) in dry tetrahydrofuran (5 mL). Puriﬁcation by ﬂash column

chromatography (eluting with 20% ethyl acetate in hexanes increasing

8.46 (s, 1H), 7.58−7.88 (m, 5H), 7.50 (d, J = 7.8 Hz, 2H), 7.41 (dd,

J = 4.7, 7.8 Hz, 1H), 7.26 (s, 1H). ESI m/z: 372 (M). HPLC (water/

ACN + 0.1% TFA gradient) >99% at 220 nm.

(4-Chlorophenyl)(4-chloro-2-ﬂuorophenyl)pyridin-3-yl Methanol

(45). General method C (pyridine) with 2-ﬂuoro-4-chlorobenzene

(361 mg, 1.73 mmol), n-butyllithium (1.6 M in hexanes, 1.0 mL, 1.6

mmol), dry diethyl ether (3 mL), 13Biii (250 mg, 1.15 mmol), and

dry tetrahydrofuran (3 mL). Puriﬁcation by ﬂash column chromatog-

raphy (eluting with 10% ethyl acetate in dichloromethane increasing to

1

to 40%) gave 52 as an amber glass (200 mg, 53%). H NMR (300

MHz, CDCl₃) δ 8.47 (dd, J = 0.7, 2.3 Hz, 1H), 8.42 (dd, J = 1.6, 4.8

Hz, 1H), 7.61−7.66 (m, 1H), 7.57 (d, J = 8.2 Hz, 2H), 7.44 (d, J = 8.2

Hz, 2H), 7.14−7.25 (m, 3H), 7.07−7.13 (m, 2H), 3.72 (s, 1H), 2.91

(spt, J = 6.9 Hz, 1H), 1.24 (d, J = 6.9 Hz, 6H). GC/MS (m/z = 371

[M]). HPLC (method 1) 97% at 220 nm.

(4-Chlorophenyl)-(2,4-diﬂuorophenyl)pyridin-3-yl Methanol (53).

General method C (pyridine) with 53Bi (300 mg, 1.19 mmol), 3-

bromopyridine (281 mg, 1.78 mmol), dry diethyl ether (3 mL), dry

1

35% ethyl acetate) gave 45 as a white solid (223 mg, 56%). H NMR

(300 MHz, chloroform-d) δ 8.55 (dd, J = 1.51, 4.90 Hz, 1H), 8.47 (d,

J = 2.26 Hz, 1H), 7.58−7.65 (m, 1H), 7.24−7.41 (m, 3H), 7.03−7.24

(m, 4H), 6.83 (t, J = 8.6 Hz, 1H), 3.60 (d, J = 8.3 Hz, 1H). GCMS

m/z 347. HPLC (water/ACN + 0.1% TFA gradient) 97.2% at 220 nm.

4200

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

tetrahydrofuran (3 mL), and n-butyllithium (1.6 M solution in

hexanes, 1.04 mL, 1.67 mmol). The crude material was absorbed onto

silica and puriﬁed by ﬂash chromatography (eluting with 5% ethyl

acetate in dichloromethane increasing to 10% ethyl acetate) to give 53

as a white solid (262 mg, 66%). ¹H NMR (300 MHz, chloroform-d) δ

8.55 (dd, J = 1.3, 4.7 Hz, 1H), 8.46 (d, J = 2.1 Hz, 1H), 7.55−7.70 (m,

1H), 7.13−7.41 (m, 5H), 6.73−6.95 (m, 3H), 3.61 (d, J = 8.3 Hz,

1H). GCMS m/z 331. HPLC (method 1) 96.2% at 220 nm.

(4-(Propan-2-yloxy)phenyl)(2-ﬂuoro-4-methylphenyl)pyridin-3-yl

Methanol (59). General method C (pyridine) with 4-bromo-3-

ﬂuorotoluene (294 mg, 1.55 mmol), dry diethyl ether (4 mL), n-

butyllithium (0.9 mL, 1.45 mmol, 1.6 M solution in hexanes), and

35Biii (250 mg, 1.04 mmol) in dry tetrahydrofuran (4 mL). The crude

material was absorbed onto silica gel and puriﬁed by ﬂash column

chromatography (eluting with 5% ethyl acetate in dichloromethane to

increasing to 20% ethyl acetate) to give 59 as a yellow gummy solid

1

(84 mg, 23%). H NMR (300 MHz, chloroform-d) δ 8.41−8.60 (m,

(4-(Triﬂuoromethyl)phenyl)(4-chloro-2-ﬂuorophenyl)pyridin-3-yl

Methanol (54). General method C (pyridine) with 1-bromo-4-chloro-

2-ﬂuorobenzene (25 mg, 1.2 mmol), dry diethyl ether (5 mL), n-

butyllithium (1.6 equiv of a 1.6 M solution in hexanes, 0.69 mL, 1.11

mmol), 54Biii (200 mg, 0.8 mmol), and dry tetrahydrofuran (3 mL).

Puriﬁcation by ﬂash column chromatography (eluting with 5% ethyl

acetate in dichloromethane, increasing to 15% ethyl acetate) gave 54

as a white powder (100 mg, 33%). ¹H NMR (300 MHz, chloroform-d)

δ 8.61 (d, J = 3.6 Hz, 1H), 8.51 (s, 1H), 7.63−7.66 (m, 3H), 7.44 (d,

J = 8.3 Hz, 2H), 7.31−7.37 (m, 1H), 7.18 (dd, J = 2.0, 11.6 Hz, 1H),

7.12 (d, J = 8.5 Hz, 1H), 6.82 (t, J = 8.5 Hz, 1H), 3.49 (d, J = 8.7 Hz,

1H). GCMS m/z = 381. HPLC (method 1) 98.4% at 220 nm.

(4-Chlorophenyl)(2-ﬂuoro-4-(triﬂuoromethyl)phenyl)pyridin-3-yl

Methanol (55). General method C (pyridine) with 3-bromopyridine

(97 mg, 0.61 mmol), dry diethyl ether (5 mL), n-butyllithium (0.36

mL, 0.57 mmol, 1.6 M solution in hexanes), and 55Bii (124 mg, 0.41

mmol) in dry tetrahydrofuran (5 mL). The crude material was

absorbed onto silica gel and puriﬁed by ﬂash column chromatography

(eluting with 5% ethyl acetate in dichloromethane. Further puriﬁcation

via reverse phase chromatography eluting with acetonitrile gave 55 as a

pale-yellow powder (3 mg, 22%). ¹H NMR (300 MHz, chloroform-d)

δ 8.23−8.77 (m, 2H), 7.63 (d, J = 7.9 Hz, 1H), 7.28−7.45 (m, 5H),

7.17−7.24 (m, 2H), 7.12 (t, J = 7.9 Hz, 1H), 3.66 (d, J = 7.8 Hz, 1H).

GCMS m/z = 381. HPLC (water/ACN + 0.1% TFA gradient) 97.1%

at 220 nm.

2H), 7.63−7.66 (m, 1H), 7.21−7.35 (m, 1H), 7.13 (d, J = 8.7 Hz, 2H),

6.77−6.98 (m, 4H), 6.59−6.74 (m, 1H), 4.55 (spt, J = 6.0 Hz, 1H), 3.52

(d, J = 10.0 Hz, 1H), 2.35 (s, 3H), 1.34 (d, J = 6.0 Hz, 6H). GC/MS

m/z = 351. HPLC (water/ACN + 0.1% TFA gradient) 97.9% at 220 nm.

4-((Propan-2-yloxy)phenyl)(4-chloro-2-ﬂuorophenyl)pyridin-3-yl

Methanol (60). General method C (pyridine) with 1-bromo-4-chloro-

2-ﬂuorobenzene (260 mg, 1.24 mmol), dry diethyl ether (3 mL), n-

butyllithium (0.73 mL, 1.16 mmol, 1.6 M solution in hexanes), and

35Biii (200 mg, 0.83 mmol) in dry tetrahydrofuran (3 mL). The crude

material was absorbed onto silica gel and puriﬁed by ﬂash column

chromatography (eluting with 5% ethyl acetate in dichloromethane to

increasing to 10% ethyl acetate) to give 60 as a pale-yellow foam (33

mg, 11%). ¹H NMR (300 MHz, chloroform-d) δ 8.53 (m, 2H),

7.64(d, J = 11.8 Hz, 1H), 7.27−7.37 (m, 1H), 7.03−7.17 (m, 4H),

6.79−6.92 (m, 3H), 4.55 (spt, J = 6.0 Hz, 1H), 3.36 (d, J = 7.9 Hz,

1H), 1.38−1.39 (m, 1H), 1.34 (d, J = 6.0 Hz, 1H). GC/MS m/z =

371. HPLC (method 1) 96.2% at 220 nm.

Bis(4-(iso-propoxy)phenyl)pyridin-3-yl Methanol (61). General

method C (pyridine) with 34Bii (0.759 g, 3.53 mmol), dry diethyl

ether (10 mL), n-butyllithium (2.05 mL, 3.28 mmol, 1.6 M solution

in hexanes), and 35Biii (0.608 g, 2.52 mmol) in dry tetrahydrofuran

(6 mL). The crude material was absorbed onto silica gel and puriﬁed

by ﬂash column chromatography (eluting with 5% ethyl acetate in

dichloromethane increasing to 40% ethyl acetate). Further puriﬁcation

by reverse phase column chromatography eluting with 50% acetonitrile in

(4-Chlorophenyl)(4-bromo-2-ﬂuorophenyl)pyridin-3-yl Methanol

(56). General method C (pyridine) with 3-bromopyridine (524 mg,

3.3 mmol), dry diethyl ether (5 mL), n-butyllithium (1.93 mL, 3.08

mmol, 1.6 M solution in hexanes), and 56 Bi (690 mg, 2.2 mmol) in

dry tetrahydrofuran (5 mL). The crude material was absorbed onto

silica gel and puriﬁed by ﬂash column chromatography (eluting with

5% ethyl acetate in dichloromethane increasing to 20% ethyl acetate)

1

water gave 61 as a pale-yellow glass (50 mg, 5%). H NMR (300 MHz,

chloroform-d) δ 8.37−8.64 (m, 2H), 7.68 (d, J = 7.7 Hz, 1H), 7.23 (m,

1H), 7.13 (d, J = 8.8 Hz, 4H), 6.82 (d, J = 8.8 Hz, 4H), 4.54 (spt, J = 6.0

Hz, 2H), 2.80 (s, 1H), 1.33 (d, J = 6.0 Hz, 12H). GC/MS m/z = 377.

HPLC (water/ACN + 0.1% TFA gradient) >99% at 220 nm.

Bis(4-triﬂuoromethylphenyl)pyridin-3-yl Methanol (62). A 250 mL

three-necked ﬂask dried under an atmosphere of nitrogen was charged

with magnesium turnings (630 mg, 25.9 mmol) and heated further

with a heat gun under nitrogen. In the attached dropping funnel was

added 4-bromobenzotriﬂuoride (5.95 g, 26.5 mmol) in THF (40 mL).

Approximately 3 mL of the solution was added to the magnesium,

along with 2 drops of 1,2-dibromoethane. The solution was warmed

using a heat gun to initiate the reaction, as evidenced by the

appearance of small bubbles. The remaining THF solution was added

dropwise over 30 min and, upon completion of addition, the reaction

mixture was heated under reﬂux for 30 min. On cooling to room

temperature, a solution of ethyl pyridine-2-carboxylate (1 g 6.62

mmol) in THF (10 mL) was added and the mixture heated for a

further 3 h under reﬂux and then left to stir at room temperature

overnight. A saturated, aqueous solution of ammonium chloride (50 mL)

was added and the mixture extracted into dichloromethane (50 mL).

Brine (40 mL) was added to break down the resultant emulsion, and the

mixture was ﬁltered through a pad of Celite. The organic phase was

separated, dried (MgSO₄), ﬁltered, and concentrated under reduced

pressure. Puriﬁcation via column chromatography (eluent 50% EtOAc in

hexanes) gave 62 as an orange solid (176 mg, 7%). ¹H NMR (300 MHz,

chloroform-d) δ 8.39−8.54 (m, 2H), 7.55−7.66 (m, 5H), 7.42 (d, J = 8.3

Hz, 4H), 7.22−7.33 (m, 1H), 3.59 (br s, 1H). MS m/z = 397. HPLC

(water/ACN + 0.1% TFA gradient) 98.8% at 220 nm.

1

to give 56 as an oﬀ-white powder (573 mg, 66%). H NMR (300

MHz, chloroform-d) δ 8.56 (dd, J = 1.8, 4.8 Hz, 1H), 8.47 (d, J = 2.2

Hz, 1H), 7.59−7.63(m, 1H), 7.27−7.36 (m, 3H), 7.16−7.25 (m, 3H),

6.75 (t, J = 8.3 Hz, 1H), 3.49 (d, J = 8.5 Hz, 1H). GC/MS m/z = 393.

HPLC (water/ACN + 0.1% TFA gradient) 98% at 220 nm.

(4-Chlorophenyl)(2-ﬂuoro-4-(propan-2-yloxy)phenyl)pyridin-3-yl

Methanol (57). General procedure C (pyridine) with 87 (305 mg,

1.31 mmol), dry diethyl ether (5 mL), n-butyllithium (0.756 mL, 1.21

mmol, 1.6 M solution in hexanes), and 13Biii (219 mg, 1 mmol) in

dry tetrahydrofuran (5 mL). The crude material was absorbed onto

silica gel and puriﬁed by ﬂash column chromatography (eluting with

5% ethyl acetate in dichloromethane) to give 57 as an oﬀ-white

powder (210 mg, 56%). ¹H NMR (300 MHz, chloroform-d) δ 8.55 (d,

J = 3.6 Hz, 1H), 8.49 (s, 1H), 7.61−7.64 (m, 1H), 7.29−7.36 (m, 2H),

7.15−7.24 (m, 2H), 6.48−6.70 (m, 3H), 4.50 (spt, J = 6.0 Hz,1H),

3.47−3.58 (m, 1H), 1.34 (d, J = 6.0 Hz, 6H). GC/MS m/z = 371.

HPLC (water/ACN + 0.1% TFA gradient) 96% at 220 nm.

4-((4-Chlorophenyl)(hydroxy)pyridin-3-ylmethyl)-3-ﬂuorobenzo-

nitrile (58). General method D with aryl bromide 56 (527 mg, 1.34

mmol), potassium ferricyanide (K₄[Fe(CN)₆]·3H₂O) (1.13 g, 2.68

mmol), palladium(II)acetate (36 mg, 12 mol %), anhydrous sodium

carbonate (213 mg, 2.01 mmol), and anhydrous N,N-dimethylaceta-

mide (8 mL). The crude material was absorbed onto silica gel and

puriﬁed by ﬂash column chromatography (eluting with 10% ethyl

acetate in dichloromethane) to give 58 as a pale-brown powder (68

mg, 14%). ¹H NMR (300 MHz, chloroform-d) δ 8.59 (br s, 1H), 8.49

(br s, 1H), 7.62 (d, J = 10.8 Hz, 1H), 7.40−7.48 (m, 2H), 7.30−7.39

(m, 3H), 7.13−7.24 (m, 3H), 3.46 (br s, 1H). GC/MS m/z = 338.

HPLC (water/ACN + 0.1% TFA gradient) 95.3% at 220 nm.

Bis(4-chloro-2-ﬂuorophenyl)pyridin-3-yl Methanol (63). General

procedure C (pyridine) 1-bromo-4-chloro-2-ﬂuorobenzene (249 mg,

1.19 mmol), dry diethyl ether (3 mL), n-butyllithium (0.69 mL, 1.55

mmol, 1.6 M solution in hexanes), and 63Biii (200 mg, 0.85 mmol) in

dry tetrahydrofuran (3 mL). The crude material was absorbed onto

silica gel and puriﬁed by ﬂash column chromatography (eluting with

5% ethyl acetate in dichloromethane increasing to 10% ethyl acetate)

4201

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

1

to give 63 as a white powder (33 mg, 11%). H NMR (300 MHz,

chloroform-d) δ 8.46−8.61 (m, 2H), 7.64 (d, J = 8.1 Hz, 1H), 7.27−

7.35 (m, 1H), 7.04−7.21 (m, 6H), 3.68 (t, J = 4.8 Hz, 1H). GC/MS m/z =

365. HPLC (water/ACN + 0.1% TFA gradient) 97% at 220 nm.

tetrahydrofuran (5 mL). The solution was cooled to −78 °C, and n-

butyllithium (1.6 M in hexanes, 2.5 mL, 0.008 mol) was added

dropwise over 10 min. The resultant brown suspension was stirred at

low temperature for 1 h. Chlorotrimethylsilane (0.5 mL, 0.004 mol)

was added and the reaction slowly warmed to −20 °C, giving a solu-

tion which was recooled to −78 °C. n-Butyllithium (1.6 M in hexanes,

1.25 mL, 0.004 mol) was slowly added, the mixture stirred for 15 min,

and then a solution of 13Biii (0.435 g, 0.002 mol) in tetrahydrofuran

(4 mL) added. After stirring at −78 °C for 30 min, the mixture was

allowed to warm slowly to room temperature overnight and then

quenched with a saturated solution of ammonium chloride (50 mL),

extracted into ethyl acetate (2 × 30 mL), dried (MgSO₄), ﬁltered, and

concentrated under reduced pressure. Puriﬁcation by ﬂash column

chromatography (eluting with 20% ethyl acetate in hexanes) gave 70

(250 mg, 35%) as a tan solid. ¹H NMR (300 MHz, DMSO-d₆) δ 9.43

(br s, 2H), 8.69−8.87 (m, 2H), 8.24 (d, J = 8.1 Hz, 1H), 7.77−7.91

(m, 2H), 7.37−7.54 (m, 4H), 6.82 (s, 1H). [M + 1] 318. HPLC

(water/ACN + 0.1% TFA gradient) 98.51% at 220 nm.

Synthesis of Compounds in Table 4. (4-Chlorophenyl)(thiophen-

2-yl)pyridin-3-yl methanol (64). General method C (pyridine) with

2-bromothiophene (1.95 g, 12 mmol), n-butyllithium (1.6 M in

hexanes, 7.5 mL, 12 mmol), dry diethyl ether (30 mL), 13Biii

(2 g, 9.22 mmol), and dry tetrahydrofuran (30 mL). Puriﬁca-

tion by ﬂash column chromatography (eluting with 33% ethyl

acetate in hexanes) gave 64 as a white powder (1.28 g, 46%).

¹H NMR (300 MHz, chloroform-d) δ 8.60 (d, J = 2.0 Hz, 1H),

8.52 (dd, J = 1.3, 4.7 Hz, 1H), 7.67−7.75 (m, 1H), 7.19−7.37

(m, 6H), 6.97 (dd, J = 3.7, 5.1 Hz, 1H), 6.73 (dd, J = 0.9, 3.7

Hz, 1H), 3.26 (s, 1H). GCMS m/z = 301. HPLC (water/ACN

+ 0.1% TFA gradient) 99% at 220 nm.

(4-Chloro-2-ﬂuorophenyl)(thiophen-2-yl)pyridin-3-yl Methanol

(65). General method C (pyridine) with 2-bromothiophene (167

mg, 1.02 mmol), n-butyllithium (1.6 M in hexanes, 0.58 mL, 0.93

mmol), dry diethyl ether (4 mL), 13Biii (200 mg, 0.85 mmol), and

dry tetrahydrofuran (4 mL). Puriﬁcation by ﬂash column chromatog-

raphy (eluting with 10% ethyl acetate in hexanes increasing to 20%

ethyl acetate) gave 65 as a yellow glass (179 mg, 66%). ¹H NMR (300

MHz, chloroform-d) δ 8.44 (br s, 2H), 7.64 (d, J = 8.1 Hz, 1H), 7.28

(d, J = 4.9 Hz, 1H), 7.14−7.24 (m, 2H), 6.78−7.12 (m, 4H), 6.61 (d,

J = 3.2 Hz, 1H), 3.54−4.27 (m, 1H). ESI m/z: 319 (M). HPLC

(water/ACN + 0.1% TFA gradient) >99% at 220 nm.

(4-Chlorophenyl)(thiophen-3-yl)pyridin-3-yl Methanol (66). Gen-

eral method C (pyridine) with 3-bromothiophene (248 mg, 1.52

mmol), n-butyllithium (1.6 M in hexanes, 1.0 mL, 1.6 mmol), dry

diethyl ether (3 mL), 13Biii (248 mg, 1.38 mmol), and dry

tetrahydrofuran (3 mL). Puriﬁcation by ﬂash column chromatography

(eluting with 10% ethyl acetate in dichloromethane increasing to 25%

N-{5-[(4-Chlorophenyl)(hydroxy)pyridin-3-ylmethyl]-1,3-thiazol-

2-yl}-2-methyl Propanamide (71). A 100 mL round-bottomed ﬂask

was charged with 70 (100 mg, 0.315 mmol) and dichloromethane

(10 mL). Upon dissolution of the solid, isobutyryl chloride (50 mg,

0.47 mmol) and triethyl amine (32 mg, 0.315 mmol) were added, the

mixture stirred at room temperature overnight and then quenched

with water (30 mL), extracted into dichloromethane (2 × 20 mL),

dried (MgSO₄), ﬁltered, and concentrated under reduced pressure.

Puriﬁcation by Flashmaster II (2 g column, eluting with ethyl acetate

increasing to 10% methanol in ethyl acetate). Material was triturated in

1

diethyl ether to give 71 (30 mg, 24%) as a yellow powder. H NMR

(200 MHz, DMSO-d₆) δ 12.05 (s, 1H), 8.4−8.6 (m, 2H), 7.70−7.80

(m, 1H), 7.30−7.50 (m, 4H), 7.17 (s, 1H), 6.92 (s, 1H), 2.60−2.85

(m, 1H), 1.107−1.140 (d, J = 6.0 Hz, 6H). [M + 1] 388. HPLC

(water/ACN + 0.1% TFA gradient) 96.67% at 220 nm.

1

ethyl acetate) gave 66 as an oﬀ-white foam (272 mg, 66%). H NMR

(4-Chlorophenyl)(2-chloro-1,3-thiazol-5-yl)pyridin-3-yl Methanol

(72). General method C (pyridine) with 2-chlorothiazole²⁸(2 g,

0.0167 mol) in tetrahydrofuran (40 mL), n-butyllithium (1.6 M in

hexanes, 10.4 mL, 0.0167 mol), 13Biii (3.4 g, 0.0167 mol), and dry

tetrahydrofuran (10 mL). Puriﬁcation by ﬂash column chromatog-

raphy (eluting with 20% ethyl acetate in hexanes increasing to 50%

ethyl acetate) gave 72 yellow glass (3.2 g, 57%). ¹H NMR (400 MHz,

chloroform-d) δ 8.23−8.51 (m, 2H), 7.65−7.67 (m, 1H), 7.16−7.46

(m, 5H), 6.96−7.10 (m, 1H), 5.37−6.18 (m, 1H). ESI m/z: 336 (M).

HPLC (water/ACN + 0.1% TFA gradient) 99.52% at 220 nm.

(4-Chlorophenyl)(pyrimidin-5-yl)pyridin-3-yl Methanol (73). Gen-

eral method C (pyridine) except n-butyllithium (1.6 M in hexanes,

1.15 mL, 1.84 mmol) added to a cold (−78 °C) solution of 5-

bromopyrimidine (406 mg, 1.84 mmol) and 13Biii (249 mg, 1.15

mmol) in dry tetrahydrofuran (10 mL). Puriﬁcation by ﬂash column

chromatography (eluting with 20% ethyl acetate in hexanes increasing

to 80% ethyl acetate). Repuriﬁcation on reverse phase silica eluting

with 30% methanol in water increasing to 60% methanol gave 73 as a

beige solid (102 mg, 30%). ¹H NMR (300 MHz, chloroform-d) δ 9.17

(s, 1H), 8.69 (s, 2H), 8.47−8.60 (m, 2H), 7.56−7.66 (m, 1H), 7.27−

7.44 (m, 3H), 7.19 (d, J = 8.5 Hz, 2H), 3.68 (s, 1H). GCMS m/z =

297. HPLC (water/ACN + 0.1% TFA gradient) 99.30% at 220 nm.

(2-Chloropyrimidin-5-yl)[4-(propan-2-yloxy)phenyl]pyridin-3-yl

Methanol (74). General method C (pyridine) except n-butyllithium

(1.6 M in hexanes, 0.8 mL, 1.28 mmol) added to a cold (−80 °C)

solution of 5-bromo-2-chloropyrimidine (267 mg, 1.38 mmol) and

35Biii (221 mg, 0.919 mmol) in dry tetrahydrofuran (8 mL). Puriﬁca-

tion by ﬂash column chromatography (eluting with 20% ethyl acetate

in hexanes increasing to 100% ethyl acetate, then 10% methanol in

ethyl acetate). Repuriﬁcation twice on reverse phase silica eluting with

40% methanol in water increasing to 70% methanol in water, then 50%

(300 MHz, chloroform-d) δ 8.43−8.55 (m, 2H), 7.63−7.71 (m, 1H),

7.18−7.44 (m, 6H), 6.84−7.01 (m, 2H), 3.37 (s, 1H). GCMS m/z

301. HPLC (water/ACN + 0.1% TFA gradient) 96.90% at 220 nm.

(2-Benzothiophenyl)(4-triﬂuoromethylphenyl)pyrid-3-yl) Metha-

nol (67). General method C (pyridine) with 4-bromobenzotriﬂuoride

(282 mg, 1.25 mmol), n-butyllithium (1.6 M in hexanes, 0.74 mL, 1.18

mmol), dry diethyl ether (3 mL), 67Biii (200 mg, 0.84 mmol), and dry

tetrahydrofuran (3 mL). Puriﬁcation by ﬂash column chromatography (eluting

with 10% ethyl acetate in dichloromethane increasing to 66% ethyl acetate)

gave 67 as a white foam (202 mg, 62%). ¹H NMR (300 MHz, chloroform-d)

δ 8.59 (d, J = 1.9 Hz, 1H), 8.50 (dd, J = 1.1, 4.7 Hz, 1H), 7.70−7.81 (m, 2H),

7.52−7.69 (m, 5H), 7.21−7.42 (m, 3H), 6.91 (s, 1H), 4.06 (s, 1H). GCMS

m/z 385. HPLC (method 1) 7.24 min 99.25% at 220 nm.

(4-Chlorophenyl)(thiazol-2-yl)pyridin-3-yl Methanol (68). General

method C (pyridine) with 2-bromothiazole (284 mg, 1.73 mmol), n-

butyllithium (1.6 M in hexanes, 1.0 mL, 1.6 mmol), dry diethyl ether

(3 mL), 13Biii (250 mg, 1.15 mmol), and dry tetrahydrofuran (3 mL).

Puriﬁcation by ﬂash column chromatography (eluting with 33% ethyl

acetate in dichloromethane) gave 68 as a yellow glass (273 mg, 78%).

¹H NMR (300 MHz, chloroform-d) δ 8.53 (d, J = 2.1 Hz, 1H), 8.47

(dd, J = 1.4, 4.8 Hz, 1H), 7.83 (d, J = 3.2 Hz, 1H), 7.69−7.76 (m, 1H),

7.19−7.41 (m, 6H), 5.03 (s, 1H). GCMS [M + H] = 303.2. HPLC

(water/ACN + 0.1% TFA gradient) 95.01% at 220 nm.

(4-Chlorophenyl)(1,3-thiazol-5-yl)pyridin-3-yl Methanol (69).

General method C (pyridine) with 5-bromothiazole (153 mg, 0.93

mmol), n-butyllithium (1.6 M in hexanes, 0.6 mL, 0.96 mmol), dry

diethyl ether (4 mL), 13Biii (200 mg, 0.94 mmol), and dry tetra-

hydrofuran (2 mL). Puriﬁcation by ﬂash column chromatography

(eluting with 20% ethyl acetate in hexanes) gave 69 as an oﬀ-white

1

powder (46 mg, 16%). H NMR (300 MHz, chloroform-d) δ 8.80 (s,

1

acetonitrile in water gave 74 as an oﬀ-white glass (76 mg, 23%). H

1H), 8.47−8.60 (m, 2H), 7.68 (td, J = 1.9, 8.1 Hz, 1H), 7.44 (s, 1H),

7.27−7.38 (m, 5H), 3.96 (s, 1H). ESI m/z: 302 (M). HPLC (water/

ACN + 0.1% TFA gradient) 97.63% at 220 nm.

(4-Chlorophenyl)(2-amino-1, 3-thiazol-5-yl)pyridin-3-yl Metha-

nol Dihydrochloride (70). A dried 100 mL three-necked ﬂask, under

nitrogen, was charged with 2-aminothiazole (0.2 g, 0.002 mol) and

NMR (300 MHz, chloroform-d) δ 8.50−8.67 (m, 4H), 7.58−7.70

(m, 1H), 7.32 (dd, J = 4.8, 8.0 Hz, 1H), 7.06 (d, J = 8.9 Hz, 2H),

6.81−6.93 (m, 2H), 4.57 (spt, J = 6.0 Hz, 1H), 3.23 (s, 1H), 1.35 (d,

J = 6.0 Hz, 6H). ESI m/z: 355 (M). HPLC (water/ACN + 0.1% TFA

gradient) 98.73% at 220 nm.

4202

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

(4-Chlorophenyl)[2-(propan-2-yloxy)pyrimidin-5-yl]pyridin-3-yl

Methanol (75). General method C (pyridine) except n-butyllithium

(1.6 M in hexanes, 0.8 mL, 1.28 mmol) added to a cold (−80 °C)

solution of 88 (200 mg, 0.92 mmol) and 13Biii (299 mg, 1.38 mmol)

in dry tetrahydrofuran (8 mL). Puriﬁcation by ﬂash column chro-

matography (eluting with 20% ethyl acetate in hexanes increasing to

100% ethyl acetate, then 10% methanol in ethyl acetate). Repuriﬁca-

tion on reverse phase silica eluting with 40% methanol in water in-

creasing to 60% methanol in water gave 75 as a white solid (124 mg,

38%). ¹H NMR (300 MHz, chloroform-d) δ 8.51−8.64 (m, 2H), 8.39

(s, 2H), 7.64 (td, J = 1.9, 8.0 Hz, 1H), 7.28−7.43 (m, 3H), 7.17−7.26

(m, 2H), 5.18−5.36 (m, 1H), 3.10 (s, 1H), 1.40 (d, J = 6.2 Hz, 7H).

HPLC (water/ACN + 0.1% TFA gradient) 97.02% at 220 nm.

(4-Chloro-2-ﬂuorophenyl)[2-(propan-2-yloxy)pyrimidin-5-yl]-

pyridin-3-yl Methanol (76). General method C (pyridine) except n-

butyllithium (1.6 M in hexanes, 0.8 mL, 1.28 mmol) added to a cold

(−80 °C) solution of 87 (299 mg, 1.38 mmol) and 63Biii (21 mg,

0.92 mmol) in dry tetrahydrofuran (8 mL). Puriﬁcation by ﬂash column

chromatography (eluting with 20% ethyl acetate in hexanes increasing to

100% ethyl acetate, then 10% methanol in ethyl acetate). Repuriﬁcation on

reverse phase silica eluting with 40% acetonitrile in water increasing to

REFERENCES

■

(1) Chagas Disease (American Trypanosomiasis), Fact Sheet no. 340;

World Health Organisation: Geneva, 2010; http://www.who.int.

mediacentre/factsheets/fs340/en/index.html (Accessed September

7, 2011).

(2) Ribeiro, I.; Sevcsik, A.-M.; Alves, F.; Diap, G.; Don, R.; Harhay,

M. O.; Chang, S.; Pecoul, B. New, improved treatments for Chagas

disease: from the R&D pipeline to the patients. PloS Negl. Trop. Dis.

2009, 3, e484.

(3) Nature Outlook Chagas Disease Supplement. Nature 2010, 465,

7301 (Suppl), S3−S22.

(4) Chatelain, E.; Ioset, J.-R. Drug discovery and development for

neglected diseases: the DNDi model. Drug Des., Dev. Ther. 2011, 5,

175−181.

́

(5) (a) Cerecetto, H.; Gonzalez, M. Anti-T. cruzi agents: our

experience in the evaluation of more than ﬁve hundred compounds.

Mini-Rev. Med. Chem. 2008, 8, 1355−1383. (b) von Geldern, T.;

Harhay, M. O.; Scandale, I.; Don, R. Kinetoplastid Parasites. Top. Med.

Chem. 2011, 7, 181−241.

(6) Duschak, V. G.; Couto, A. S. An insight on targets and patented

drugs for chemotherapy of Chagas disease. Recent Pat. Anti-Infect. Drug

Discovery 2007, 2, 19−51.

1

70% methanol in water gave 76 as an oﬀ-white glass (90 mg, 26%). H

NMR (300 MHz, chloroform-d) δ 7.58−8.62 (m, 1H), 8.51 (s, 1H), 8.38

(s, 2H), 7.56−7.72 (m, 1H), 7.34 (dd, J = 4.7, 7.9 Hz, 1H), 7.08−7.22 (m,

2H), 6.96−7.05 (m, 1H), 5.28 (quin, J = 6.2 Hz, 1H), 3.57 (d, J = 7.9 Hz,

1H), 1.41 (d, J = 6.2 Hz, 6H). ESI m/z: 373 (M). HPLC (water/ACN +

0.1% TFA gradient) >99% at 220 nm.

(7) (a) ParasitesAmerican Trypanosomiasis (Also Known as Chagas

Disease): Biology; Centers for Disease Control and Prevention (CDC):

Atlanta, 2012; http://www.cdc.gov/parasites/chagas/biology.html

(Accessed January 23, 2012); (b) Andrade, L. O.; Andrews, N. W.

The Trypanosoma cruzi−host−cell interplay: location, invasion,

retention. Nature Rev. Microbiol. 2005, 3, 819−824.

ASSOCIATED CONTENT

* Supporting Information

■

S

(8) Bern, C. Anti-trypanosomal therapy for chronic Chagas disease.

N. Engl. J. Med. 2011, 364, 2527−2534.

Additional synthetic methods for the preparation of inter-

mediates to ﬁnal compounds and spectroscopic/analytical data.

General description of solubility, microsomal stability and cytoc-

hrome P450 3A4/5 inhibition assays. This material is available free

of charge via the Internet at http://pubs.acs.org.

(9) Werner, A. Current and developing therapeutic agents in the

treatment of Chagas disease. Drug Des., Dev. Ther. 2010, 4, 243−253.

(10) (a) Wilkinson, S. R.; Bot, C.; Kelly, J. M.; Hall, B. S.

Trypanocidal activity of nitroaromatic prodrugs: current treatments

and future perspectives. Curr. Top. Med. Chem. 2011, 11, 2072−2084.

(b) Hall, B. S.; Wu, X.; Hu, L.; Wilkinson, S. R. Exploiting the drug-

activating properties of a novel trypanosomal nitroreductase.

Antimicrob. Agents Chemother. 2010, 54, 1193−1199. (c) Wilkinson,

S. R.; Kelly, J. M. Trypanocidal drugs: mechanisms, resistance and new

targets. Expert Rev. Mol. Med. 2009, 11, e31. (c) Wilkinson, S. R.;

Taylor, M. C.; Horn, D. A mechanism for cross-resistance to

nifurtimox and benznidazole in trypanosomes. Proc. Natl. Acad. Sci.

U.S.A. 2008, 105, 5022−5027.

AUTHOR INFORMATION

Corresponding Author

*Phone: +61 (0)8 9360 6386. Fax: +61 (0)8 9360 7699.

E-mail: martine.keenan@epichem.com.au.

■

Notes

The authors declare no competing ﬁnancial interest.

(11) Maya, J. D.; Cassels, B. K.; Iturriaga-Vas

Faundez, M.; Galanti, N.; Ferreira, A.; Morello, A. Mode of action of

́

quez, P.; Ferreira, J.;

ACKNOWLEDGMENTS

́

■

natural and synthetic drugs against Trypanosoma cruzi and their

interaction with the mammalian host. Comp. Biochem. Physiol., Part A:

Mol. Integr. Physiol. 2007, 146, 601−620.

(12) (a) Bahia, M. T.; Talvani, A.; Chang, S.; Ribeiro, I. (2009)

Combination of benznidazole and nifurtimox plus posaconazole

enhances activity against Trypanosoma cruzi in experimental Chagas

disease. American Society of Tropical Medicine and Hygiene 58th

Annual Meeting, Washington, DC, November 18−22, 2009, 746.

(b) Olivieri, B. P.; Molina, J. T.; de Castro, S. L.; Pereira, M. C.;

DNDi is grateful to its donors, public and private, who have

provided funding to DNDi since its inception in 2003. With the

support of these donors, DNDi is well on its way to achieving the

objectives of building a robust pipeline and delivering 6−8 new

treatments by 2014. A full list of DNDi’s donors can be found at

http://www.dndi.org/index.php/donors.html?ids=8. For the work

described in this paper, DNDi received ﬁnancial support from the

following donors: Department for International Development

(DFID)/UNITED KINGDOM, GiZ, on behalf of the Govern-

ment of the Federal Republic of Germany/GERMANY, Ministry

of Foreign and European Aﬀairs (MAEE)/FRANCE, Spanish

Agency for International Development Cooperation (AECID)/

SPAIN, Swiss Agency for Development and Cooperation (SDC)/

Calvet, C. M.; Urbina, J, A.; Araujo-Jorge, T. C. A comparative study of

́

posaconazole and benznidazole in the prevention of heart damage and

promotion of trypanocidal immune response in a murine model of

Chagas disease. Int. J. Antimicrob. Agents 2010, 36, 79−83.

(13) (a) Urbina, J. A. Mem. Inst. Oswaldo Cruz 2009, 104 (suppl. 1),

311−318. (b) Eisai and DNDi enter into a collaboration and license

agreement to develop a new drug for Chagas disease. DNDi Press

Releases; DNDi: Geneva, 2009; http://www.dndi.org/press-releases/

532-eisai-and-dndi-enter-into-a-collaboration.html (Accessed Septem-

ber 7, 2011).

́ ̀

SWITZERLAND, Medecins Sans Frontieres (Doctors without

Borders)/INTERNATIONAL, and a Swiss foundation. The

donors had no role in study design, data collection and analysis,

decision to publish, or preparation of the manuscript.

(14) Lepesheva, G. I.; Hargrove, T. Y.; Anderson, S.; Kleshchenko,

Y.; Furtak, V.; Wawrzak, Z.; Villalta, F; Waterman, M. R. Structural

Insights into Inhibition of Sterol 14-Demethylase in the Human

Pathogen Trypanosoma cruzi. J. Biol. Chem. 2010, 285, 25582−25590.

ABBREVIATIONS USED

Tc and T. cruzi, (Trypanosoma cruzi); TcVI, (strain of

Trypanosoma cruzi belonging to group VI)

■

4203

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Journal of Medicinal Chemistry

Article

(15) Chen, C.-K.; Leung, S. S. F.; Guilbert, C.; Jacobson, M. P.;

McKerrow, J. H.; Podust, L. M. Structural Characterization of CYP51 from

Trypanosoma cruzi and Trypanosoma brucei bound to the antifungal

drugs posaconazole and ﬂuconazole. PloS Negl. Trop. Dis. 2010, 4, e651.

(16) Doyle, P. S.; Chen, C.-K.; Johnston, J. B.; Hopkins, S. D.; Leung,

S, S. F.; Jacobsen, M. P.; Engel, J. C.; McKerrow, J. H.; Podust, L. M. A

non-azole CYP51 inhibitor cures Chagas disease in a mouse model of

acute infection. Antimicrob. Agents Chemother. 2010, 54, 2480−2488.

(17) Portal, P.; Villamil, S. F.; Alonso, G. D.; De Vas, M. G. Multiple

NADPH-cytochrome P450 reductases from Trypanosoma cruzi suggested

role on drug resistance. Mol. Biochem. Parasitol. 2008, 160, 42−51.

(18) Zingales, B.; Andrade, S. G.; Briones, M. R.; Campbell, D. A.;

Chiari, E.; Fernandes, O.; Guhl, F.; Lages-Silva, E.; Macedo, A. M.;

Machado, C. R.; Miles, M. A.; Romanha, A. J.; Sturm, N. R.;

Tibayrenc, M.; Schijman, A. G. A new consensus for Trypanosoma

cruzi intraspeciﬁc nomenclature: second revision meeting recommends

TcI to TcVI. Second Satellite Meeting. Mem. Inst. Oswaldo Cruz 2009,

104, 1051−1054.

(19) Buckner, F. S.; Verlinde, C. L. M. J.; La Flamme, A. C.; van

Voorhis, W. C. Eﬃcient technique for screening drugs for activity

against Trypanosoma cruzi using parasites expressing β-galactosidase.

Antimicrob. Agents Chemother. 1996, 40, 2592−2597.

(20) Zeiman, E.; Greenblatt, C. L.; Elgavish, S.; Khozin-Goldberg, I.;

Golenser, J. Mode of action of fenarimol against Leishmania spp. J.

Parasitol. 2008, 94, 280−286.

(21) (a) Jones, D. C.; Winter, M. A.; Hirsch, K. S.; Stamm, N.;

Taylor, H. M.; Holden, H. E.; Davenport, J. D.; Krumkalns, E. V.;

Suhr, R. G. Estrogen synthetase inhibitors. 2. Comparison of the in

vitro aromatase inhibitory activity for a variety of nitrogen heterocycles

substituted with diarylmethane or diarylmethanol groups. J. Med.

Chem. 1990, 33, 416−429. (b) Taylor, H. M.; Jones, D. C.; Davenport,

J. D.; Hirsch, K. S.; Kress, T. J.; Weaver, D. Aromatase inhibition by 5-

substituted pyrimidines and dihydropyrimidines. J. Med. Chem. 1987,

30, 1359−1365.

(22) Ekoue-Kovi, K.; Xu, H.; Wolf, C. Palladium-phosphinous acid-

catalyzed cross-coupling of aliphatic and aromatic acyl chlorides with

boronic acids. Tetrahedron Lett. 2008, 49, 5773−5776.

(23) Weissman, S. A.; Zewge, D.; Xhen, C. Ligand-free palladium-

catalyzed cyanation of aryl haldies. J. Org. Chem. 2005, 70, 1508−1510.

(24) Khong, A.; Kerfoot, M.; Botero, A.; Armstrong, T.; Keenan, M.;

Best, W.; Scandale, I.; Chatelain, E.; Thompson., R. A., A stringent in

vivo assay for evaluating the eﬃcacy of novel compounds against

Trypanosoma cruzi in mice. XIIth International Congress of Para-

sitology (ICOPA), Melbourne, Australia, August 15−20, 2010, poster

1306.

́

(25) dos Santos, F. M.; Caldas, S.; de Assis Cau, S. B.; Crepalde, G.

P.; de Lana, M.; Machado-Coelho, G. L. L.; Veloso, V. M.; Bahia, M.

T. Trypanosoma cruzi: Induction of benznidazole resistance in vivo and

its modulation by in vitro culturing and mice infection. Exp. Parasitol.

2008, 120, 385−390.

(26) (a) Vallejo, G. A.; Guhl, F.; Chiari, E.; Macedo, A. M. Species

speciﬁc detection of Trypanosoma cruzi and Trypanosoma rangeli in

vector and mammalian hosts by polymerase chain reaction

ampliﬁcation of kinetoplast minicircle DNA. Acta Trop. 1999, 72,

203−212. (b) Moser, D. R.; Kirchhoﬀ, L. V.; Donelson, J. E. Detection

of Trypanosoma cruzi by DNA ampliﬁcation using the polymerase

chain reaction. J. Clin. Microbiol. 1989, 27, 1477−1482.

(27) Yin, J.; Buchwald, S. L. Palladium-catalyzed intermolecular

coupling of ayrl halides and amides. Org. Lett. 2000, 2, 1101−1104.

(28) Cai, X.; Qian, C.; Zhai, H.; Gould, S. Tyrosine kinase inhibitors

containing a zinc binding moiety. Patent WO 200833746, A3,

September 10, 2007.

4204

dx.doi.org/10.1021/jm2015809 | J. Med. Chem. 2012, 55, 4189−4204

Article Doi

Analogues of fenarimol are potent inhibitors of trypanosoma cruzi and are efficacious in a murine model of chagas disease

DOI: 10.1021/jm2015809

Source and publish data:

Authors:

Article abstract of DOI:10.1021/jm2015809

Full text of DOI:10.1021/jm2015809

Products guided by the article

R&D Labs maybe for 1374584-09-4

Relevant to this article

Tandem Photoredox Catalysis: Enabling Carbonylative Amidation of Aryl and Alkylhalides

Stereocontrolled preparation of a nonpeptidal (-)-spirobicyclic NK-1 receptor antagonist

Solvent-Free Synthesis of α-Amino Ketones from α-Hydroxyl Ketones via A Novel Tandem Reaction Sequence Based on Heyns Rearrangement

Phase transfer catalyzed reactions of chloroform with electrophilic alkenes. Effect of solvent on reaction course

Synthesis of acylamido ketene dithioacetals and 5-oxo-4,5-dihydrobenzo[f]-1,4-thiazepine-derivatives by dithiocarboxylation of α-aza-c-nucleophiles

Synthesis and conversions of 2-substituted cinchoninic acid amides