2,6-Di(arylamino)-3-fluoropyridine Derivatives as HIV Non-Nucleoside Reverse Transcriptase Inhibitors

Article abstract of DOI:10.1021/acs.jmedchem.5b01336

New non-nucleoside reverse transcriptase inhibitors (NNRTI), which are similar in structure to earlier described di(arylamino)pyrimidines but featuring a 2,6-di(arylamino)-3-fluoropyridine, 2,4-di(arylamino)-5-fluoropyrimidine, or 1,3-di(arylamino)-4-fluorobenzene moiety instead of a 2,4-disubstituted pyrimidine moiety, are reported. The short and practical synthesis of novel NNRTI relies on two sequential Pd-catalyzed aminations as the key steps. It is demonstrated through direct comparison with reference compounds that the presence of a fluorine atom increases the in vitro anti-HIV activity, both against the wild type virus and drug-resistant mutant strains.

Full text of DOI:10.1021/acs.jmedchem.5b01336

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Article
2,6-Di(Arylamino)-3-Fluoropyridine Derivatives as
HIV Non-Nucleoside Reverse Transcriptase Inhibitors
Sergey Sergeyev, Ashok K. Yadav, Philippe Franck, Johan Michiels, Paul Lewi, Jan Heeres, Guido
Vanham, Kevin K. Ariën, Christophe M.L. Vande Velde, Hans De Winter, and Bert U. W. Maes
J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jmedchem.5b01336 • Publication Date (Web): 19 Jan 2016
Downloaded from http://pubs.acs.org on January 22, 2016
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2,6-Di(Arylamino)-3-Fluoropyridine Derivatives as HIV Non-
Nucleoside Reverse Transcriptase Inhibitors
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Sergey Sergeyev1, Ashok Kumar Yadav1, Philippe Franck1, Johan Michiels2, Paul Lewi3,†, Jan
Heeres4, Guido Vanham2,5, Kevin K. Ariën2, Christophe M. L. Vande Velde6, Hans De
Winter7, Bert U. W. Maes*,1
1 Organic Synthesis Division, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-
2020 Antwerp, Belgium
2 Virology Unit, Department of Biomedical Sciences, Institute of Tropical Medicine, Nationalestraat 155, B-
2000 Antwerp, Belgium
3 Shakturana CV, Pater van Mierlostraat 18, 2300 Turnhout, Belgium
4 Heeres Consulting CV, Leemskuilen 18, 2350 Vosselaar, Belgium
5 Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
6 Faculty of Applied Sciences, University of Antwerp, Salesianenlaan 90, 2660 Hoboken, Belgium
7 Medicinal Chemistry, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1,
2610 Wilrijk, Belgium
† deceased
ABSTRACT: New non-nucleoside reverse transcriptase inhibitors (NNRTI), which are similar in structure to earlier
described di(arylamino)pyrimidines but featuring 2,6-di(arylamino)-3-fluoropyridine, 2,4-di(arylamino)-5-
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fluoropyrimidine or 1,3-di(arylamino)-4-fluorobenzene moiety instead of a 2,4-disubstituted pyrimidine moiety, are
reported. The short and practical synthesis of novel NNRTI relies on two sequential Pd-catalyzed aminations as the key
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steps. It is demonstrated through direct comparison with reference compounds, that the presence of a fluorine atom
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increases the in vitro anti-HIV activity, both against the wild type virus and drug-resistant mutant strains.
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Introduction. At the end of 2012, an estimated 35.3 million people were living with HIV infection worldwide. There
were 2.3 million new infections and 1.6 million people died of HIV/AIDS globally that same year. In the Western world,
HIV/AIDS is no longer a fatal disease: life expectancy with adequate anti-retroviral treatment and care is more than 24
years after HIV-infection. Much of that success is due to the introduction of HAART (highly active antiretroviral
treatment) by means of combinations of two or three compounds belonging to different classes of anti-HIV compounds.1
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HAART consists of the combination of several active components belonging to different classes of anti-HIV compounds
such as protease inhibitors (PI), integrase inhibitors (INI), nucleoside reverse transcriptase inhibitors (NRTI) and non-
nucleoside reverse transcriptase inhibitors (NNRTI). A major problem in the HIV treatment remains the emergence of
resistance of the virus against the currently available drugs, whatever class of anti-HIV compounds they belong to.
Application of HAART for the treatment of HIV infection only solves this problem in part, and HAART may become
inefficient once resistance to one or more of the drugs used in combination is developed. Finally, none of the currently
available anti-HIV drugs or multi-drug therapies allows for the eradication of the virus, causing the need for life-long
treatment which possibly results in multidrug resistance. For this reason, there is a continuous need for the development
of new anti-HIV combination therapies. In order to treat drug-resistant HIV infection, new components with novel
chemical structures for such combination therapies, possessing new modes of action are necessary.
HIV-1 reverse transcriptase (RT) is one of the most important viral enzymes and plays a unique role in the HIV-1 life
cycle. It has two known drug-target sites, the substrate catalytic site and an allosteric site that is distinct from, but located
closely to, the substrate site.2, 3 Non-nucleoside reverse transcriptase inhibitors (NNRTIs) interact with the allosteric site
in a non-competitive manner to distort the enzyme’s active conformation and thus disrupt the function of the enzyme.2, 4
It is demonstrated by XRD analysis, that many NNRTIs form a hydrogen bond with a K101 amino acid residue in the
reverse transcriptase binding site.5, 6 For example, in Etravirine (1, TMC-125, Figure 1a), which was recently approved as a
next-generation NNRTI for AIDS therapy, the NH group of the arylamine and the N atom in the pyrimidine ring of the
drug are involved in the hydrogen bonding with the enzyme. It was found that 1 is highly potent against wild-type and a
number of mutant HIV strains with nanomolar EC50 values and has a high genetic barrier to delay the emergence of drug-
resistance.7, 8 A number of other NNRTIs with an azaheteroaromatic ring C featuring two arylamino substituents were
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developed, such as di(arylamino)triazine (DATA)9-11 or di(arylamino)pyrimidine (DAPY)9, 10, 12-16 derivatives. Rilpivirine (2,
TMC-278) was approved by the FDA in May 2011 (Figure 1a).14, 17 It showed better potency and pharmacological profiles
than 1, and features the same hydrogen bonding sites as present in 1.6, 13 Another NNRTI, Dapivirine (3, TMC-120), is in
Phase III clinical trials by the International Partnership for Microbicides for the prevention of HIV infection with aid of a
vaginal ring, which can provide women with a protection for a longer period of time.18, 19
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Figure 1. (a) Structures of reported NNRTI 1–3. (b) General formula of the new NNRTI reported in this paper.
In a quest for novel NNRTI with improved activity, especially towards drug-resistant strains of HIV, we designed 2,6-
di(arylamino)-3-fluoropyridine derivatives (Figure 1b). These compounds are structurally similar to 2, 3 and analogues but
feature a 2,6-disubstituted 3-fluoropyridine instead of a 2,4-disubstituted pyrimidine moiety. We hypothesized that a
fluorine atom on the ring C can also participate in the interactions with the protein backbone, by way of acting as a
hydrogen bond acceptor similarly to a nitrogen atom in the pyrimidine ring of 2, and/or other weak forces which are
unique for the fluorine atom such as orthogonal C=O…F–C interactions.20 To establish the effect of the ring C on the SAR
in the fluorinated series, derivatives featuring a pyrimidine and a benzene ring C were synthesized, too (Figure 1b).
Results and discussion.
Synthesis. Our initial target was 4a, closely resembling the structure of the above-mentioned NNRTI 3. Our original
idea, which was inspired by limited information available in the patent literature,21 was to take advantage of the
commercial availability of 2,3,6-trifluoropyridine (5). The selective nucleophilic substitution in 5 was achieved upon
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reaction with deprotonated 4-aminobenzonitrile (6a) and gave 46% yield of 4-[(3,6-difluoropyridin-2-
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yl)amino]benzonitrile (7) (Scheme 1). The structure of 7 was established by XRD analysis and confirmed the substitution
exclusively in position 2 of the pyridine core. However, the attempted reaction between 7 and 2,4,6-trimethylaniline (8a)
in NMP did not give the desired 4a, but instead produced a small amount of the amidine 9 due to the competitive attack
of the aniline nucleophile on the CN group.
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Scheme 1. Initial attempts to synthesize 4a from 2,3,6-trifluoropyridinea
aReagents and conditions: (a) 6a, t-BuLi, THF, –78 °C, then 2 h at 0 °C, 46%; (b) 8a, NMP, TsOH or MsOH, 180 °C.
We therefore turned our attention to regioselective Pd-catalyzed amination on commercially available 2,6-dichloro-3-
fluoropyridine (10), as examples of regioselective Pd-catalyzed aminations involving halogenated pyridines were
previously reported.22-28 A reaction between 10 and 6a in the presence of a Pd source and XPhos ligand afforded the
desired 4-[(6-chloro-3-fluoropyridin-2-yl)amino]benzonitrile (11a), albeit in modest yield (Table SI1). Optimization of the
catalytic system (Pd source, ligand, base additive) was therefore undertaken. Xantphos ligand in combination with t-
BuONa as a base and Pd(OAc)2 as a metal source proved to be the catalytic system of choice. Further, it is essential to
stress that the reaction proceeds with complete regioselectivity, the substitution occurred exclusively at position 2 and no
substitution at position 6 was observed, as confirmed by the single crystal XRD analysis. A second Pd-catalyzed amination
reaction of the intermediate 11a with 2,4,6-trimethylaniline (8a) finally provided the target compound 4a (Table SI1 and
Scheme 3). It was found that in this case, XPhos ligand provided an acceptable yield of the amination product.
With the optimized synthetic protocol in hand, we proceeded with the synthesis of a library of 2,6-di(arylamino)-3-
fluoropyridine derivatives 4a–u starting from 10 and various anilines (6a–d, 8a–c, 12a–f, Scheme 3). Based on the
knowledge about SAR of di(arylamino)pyrimidine NNRTI10, 12 we envisaged variation of para-substituents (R1) on the ring
B and ortho- (R2, R3) and para-substituents (R4) on the ring A of 2,6-di(arylamino)-3-fluoropyridine derivatives (Figure 1b).
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Particular attention was given to compounds with R4 = (E)-CH=CHCN, based on the high activity of 2 (Figure 1a). The
anilines 12a–f necessary for the synthesis of those compounds were prepared via a Heck reaction starting from the
corresponding 4-bromoanilines 13a–e. The latter were commercially available with the exception of 4-bromo-2-fluoro-6-
methylaniline (13c), which was prepared by bromination of commercially available 2-fluoro-6-methylaniline (14) (Scheme
2). 4-Amino-3-fluoro-5-methylbenzonitrile (8c) was prepared following the published general method (Scheme 2).29
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Scheme 2. Synthesis of the aniline reagents 12a–ga
aReagents and conditions: (a) Br2, AcOH, rt, 2 h, 82%; (b) CuCN, DMF, CuI, KI, N,N'-dimethyl-1,2-ethanediamine, 110 °C, 16 h,
74%; (c) acrylonitrile, Pd(OAc)2, P(o-tolyl)3, AcONa·3H2O, DMA, 140 °C, 48 h; (d) methyl acrylate, Pd(OAc)2, P(o-tolyl)3,
AcONa·3H2O, DMA, 140 °C, 48 h, 29%.
With the anilines in hand a series of 2,6-di(arylamino)-3-fluoropyridine derivatives 4a–k,n–u was synthesized using our
optimized two-step Pd-catalyzed amination protocol (Scheme 3). Similarly, two analogues (4l,m) featuring an O rather
than an NH linkage between the ring A and the ring C were prepared using a Pd-catalyzed C–O bond formation reaction
of 11a with phenols 15a,b instead of an aniline (Scheme 3).
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With the aim to study the effect of the ring C on the biological activity, we prepared two analogues of 4a–u featuring a
pyrimidine or benzene ring C. Following a synthetic route similar to that used for the preparation of 4a–u, a Pd-catalyzed
amination reaction of 2,4-dichloro-5-fluoropyrimidine (16) with 4-aminobenzonitrile (6a) produced the intermediate 4-
[(2-chloro-5-fluoropyrimidin-4-yl)amino]benzonitrile (17) as a single regioisomer. Subsequent amination of 17 with the
corresponding anilines (8b, 12a) provided the targets 18a,b in modest yields (Scheme 4). Furthermore, compounds 19a–c
were prepared starting from commercially available 2-bromo-4-chloro-1-fluorobenzene (20) as shown in Scheme 5. The
bromine atom in 20 was selectively substituted to produce 4-[(5-chloro-2-fluorophenyl)amino]benzonitrile (21), which
was then converted to 19a–c via Pd-catalyzed amination with anilines 12a,b,d (Scheme 5).
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Finally, in order to unambiguously evaluate the effect of the fluorine atom in the 3-position of the ring C, reference
compounds 22a–d lacking a fluorine atom were synthesized. Starting from the commercially available 2,6-
dichloropyridine (23) the intermediate 4-[(6-chloropyridin-2-yl)amino]benzonitrile (24) was prepared and then used in a
second Pd-catalyzed amination step to obtain 22a–d (Scheme 6).
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Scheme 3. Synthesis of 2,6-di(arylamino)-3-fluoropyridine derivatives 4a–ua
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aReagents and conditions: (a) Pd(OAc)2, XantPhos, t-BuONa, dioxane, 110 °C, 16 h; (b) 8a–c or 12a–f or 15a,b, Pd(OAc)2,
XPhos, Cs2CO3, dioxane, 110 °C, 16 h.
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Scheme 4. Synthesis of 2,4-di(arylamino)-5-fluoropyrimidine derivatives 18a,ba
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aReagents and conditions: (a) 6a, Pd2(dba)3, XantPhos, Cs2CO3, dioxane, 110 °C, 16 h; (b) 8b or 12a, Pd(OAc)2, XPhos, Cs2CO3,
dioxane, 110 °C, 16 h.
Scheme 5. Synthesis of 1,3-di(arylamino)-4-fluorobenzene derivatives 19a–ca
aReagents and conditions: (a) 6a, Pd(OAc)2, XantPhos, t-BuONa, dioxane, 110 °C, 16 h; (b) 12a–c, Pd(OAc)2, XPhos, Cs2CO3,
dioxane, 110 °C, 16 h
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Scheme 6. Synthesis of 2,6-di(arylamino)pyridine derivatives 22a–d
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aReagents and conditions: (a) Pd(OAc)2, rac-BINAP, K2CO3, toluene, 120 °C, 24 h; (b) 8a,b or 12a,c, Pd(OAc)2, XPhos, Cs2CO3,
dioxane, 110 °C, 16 h.
In vitro studies. The details on the activity against wild type HIV-1 and cytotoxicity for the new NNRTI are
summarized in Tables 1–4. Reference data for 2 and 3 are included for comparison. It should be noted that for molecules
containing CH=CHCN moiety, in some instances we were able to isolate pure E isomers, while a mixture of E- and Z- -
isomers was obtained in some other cases, E-isomer always being a major one (see Tables 1–4). It was previously reported
by Janssen and co-workers that for 2 and a few structural analogues, in vitro activity of E-isomers was much higher than
that of the corresponding Z-isomers. Furthermore, also in this study by Janssen15 mixtures of E and Z isomers were
examined in some cases. In case of 4c, we performed activity analysis both on the 9/1 mixture of E- and Z- isomers and on
the pure E-isomer, which gave results within the experimental error (Table 1). Based on these observations, we performed
screening on the mixtures of E- and Z- -isomers for majority of compounds and assumed that minor amounts of less
active Z-isomer do not significantly affect the results.
Table 1. Activity and selectivity index of 2,6-di(arylamino)-3-fluoropyridine derivatives 4a–ua
Compound
X
R1
R2
R3
R4
E/Z
EC50
SI
[nM]
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8
2
100/0
0.72
1.4
8.3
4.7
1.5
10700
2000
2000
7100
62500
37500
13000
8100
19000
830
3
4a
4b
4c
4c
4d
4e
4f
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
O
CN
Me
Me
Me
Me
Me
Me
Me
Me
H
Me
Me
Me
Me
Me
Me
Me
Me
H
Me
CN
CN
9
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CN
CH=CHCN
CH=CHCN
CH=CHCOOMe
CH=CHCN
CH=CHCN
CN
100/0
90/10
100/0
86/14
88/12b
CN
1.6
4.4
6.2
4.6
51
CN
F
CH=CHCN
4g
4h
4i
F
CN
Cl
CH=CHCN
CN
70/30
480
15
14
Me
Me
Me
H
Me
Me
F
2000
6600
>100000
390
4j
Cl
CH=CHCN
CH=CHCN
Me
93/7
6.3
1.0
260
8.6
63
4k
4l
CN
CN
CN
Cl
100/0
H
4m
4n
4o
4p
4q
4r
4s
4t
O
Me
Me
Me
Me
Me
Me
Me
F
Me
H
Me
6400
380
NH
NH
NH
NH
NH
NH
NH
NH
CH=CHCN
CH=CHCOOMe
CH=CHCOOMe
CH=CHCN
CH=CHCN
CN
100/0
100/0
100/0
100/0
87/13
F
Me
Me
H
84
610
Cl
53
950
F
400
11
210
CN
CN
CN
COOMe
H
24000
4600
4600
2100
F
8.8
3.3
23
F
CH=CHCN
CH=CHCN
79/21
100/0
4u
Me
Me
aThe selectivity index (SI) is defined as CC50/EC50, where EC50 is the 50%-effective concentration vs. HIV virus, and CC50 is the
concentration causing death of 50% of the cells; The EC50 value was determined in TZMbl cells against the subtype B R5-tropic
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Bal virus and the CC50 value was determined in the same cells using the WST-1 assay. bRatio (E,E)/sum of (E,Z) and (Z,E)
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isomers.
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5
6
Table 2. Activity and selectivity index of 2,4-di(arylamino)-5-fluoropyrimidine derivatives 18a,b
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Compound
18a
R1
R2
R3
R4
E/Z
EC50 [nM]
2.8
SI
CN
CN
Me
Me
Me
Me
CN
> 36000
> 42000
18b
CH=CHCN
86/14
0.9
Table 3. Activity and selectivity index of 1,3-di(arylamino)-4-fluorobenzene derivatives 19a–c
Compound
R1
R2
R3
R4
E/Z
EC50 [nM]
SI
19a
19b
19c
CN
CN
CN
Me
Me
Me
Me
F
CH=CHCN
CH=CHCN
CH=CHCN
81/19
75/25
89/11
4.5
11
7400
6100
89
H
58
From the data obtained it is clear the two ortho-substituents on the ring A (R2, R3)are essential, and replacement of one
or both substituents by a hydrogen atom results in a significant drop in activity (e.g. 4c vs. 4h,r; 4j vs. 4n; 4m vs. 4l; 4e vs.
4q, Table 1). Substitution of one or both methyl groups by fluorine atoms in the ring A provided only an insignificant
effect (slight increase in activity and selectivity for 4k vs 4c; slight decrease for 4t vs. 4c and for 4s vs 4b, Table 1). A
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cyanovinyl group in the para-position of the ring A produced the best results (4c vs. 4b,d), as was expected from the
published results on 2 and analogues (Table 1).10, 12, 16 Finally, the nature of the linker between the ring A and the ring C
had no effect (4m vs. 4a, Table 1).
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Concerning the variation of the ring B, a cyano group was clearly superior to other alternatives (4b vs 4g,i, 4c vs
4e,f,j,u, and 4d vs 4o,p, Table 1). Finally, variation of the ring C provided similar results for pyridine and pyrimidine
derivatives (4b vs. 18a, 4c vs. 18b, Table 2), while derivatives with the benzene ring C systematically show a somewhat
lower activity (4c vs 19a, 4k vs. 19b, 4r vs 19c, Table 3).
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Overall, most successful were compounds closely resembling the known NNRTI 2, namely 4c,k and 18b, all displaying
EC50 close to 1.0 nM and a very high selectivity index (> 40000).
In order to unambiguously compare the effect of the fluorine atom on the anti-HIV activity of 2,6-di(arylamino)-3-
fluoropyridine derivatives, four analogues 22a–d lacking a fluorine atom on the pyridine ring were evaluated (Table 4). In
every case (4a vs 22a, 4b vs 22b, 4c vs 22c and 4k vs 22d) removal of a fluorine atom decreased the activity and selectivity
(Table 4). In case of 4k vs 22d this effect was the most pronounced; an increase of activity by ca. a factor of 6 and of the SI
by ca. a factor of 20 due to the presence of a F atom.
Table 4. Activity and selectivity index of compounds 22a–d.
Compound
R1
R2
R3
R4
E/Z
EC50 [nM]
SI
22a
22b
22c
22d
CN
CN
CN
CN
Me
Me
Me
Me
Me
Me
Me
F
Me
30
25
1400
930
CN
CH=CHCN
CH=CHCN
80/20
92/8
3.5
5.5
11000
5500
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For selected molecules which displayed a high activity against WT HIV-1, data were collected for mutant HIV-1 strains,
which have shown resistance against Nevirapine (Y181C) and Efavirenz (L100I, K103N), and site-directed mutants (pNL4.3-
K103N, pNL4.3-K103N-Y181C) (Table 5). The activity of 4c and 4k is close to or slightly higher than that of earlier reported
3, but lower than that of 2 for all strains (WT, single and double mutant). Further comparison of three 2,6-di(arylamino)-
3-fluoropyridine derivatives with their analogues lacking fluorine clearly reveals for every case (4b vs. 22b, 4c vs 22c and
4k vs. 22d) higher activity of the fluorinated derivatives and thus further underlines the advantages of a F atom on the
ring C.
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Table 5. Antiviral activity of selected compounds vs mutant HIV-1a
Compound
Y181C
L100I, K103N
EC50 [nM]
pNL4.3-K103N
EC50 [nM]
pNL4.3-K103N-Y181C
EC50 [nM]
EC50 [nM]
2
2.5
11
3.6
0.7
2.8
3.1
92
3
> 1000
> 10000
> 10000
6600
540
4a
4b
22b
4c
22c
4k
22d
130
91
1500
8.1
91
7.8
36
554
> 1000
272
25
> 1000
255
1100
aThe EC50 values were determined in TZMbl cells against Nevirapine-resistant VI829 (carrying Y181C) and Efavirenz-resistant
VI829 (carrying L100I and K103N). Both viruses are subtype C and R5-tropic. Site-directed mutants (SDMs) carrying K103N and
K103N+Y181C were used to further evaluate 2, 3, 4c and 4k. Construction of the SDMs is described elsewhere.30
Docking studies. Docking of the 4a and 22a ligands in the crystal structure of RT in complex with 313 was performed
using the Gromacs molecular dynamics and mechanics software.31 A comparison between the docked poses of 3, 4a and
22a shows little variation between the three ligands. In all cases, a hydrogen bond between the backbone oxygen of Lys-
101 of the RT and the aniline nitrogen bridging the central aromatic ring with the nitrile-substituted ring is observed. The
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main difference between the binding of 4a on the one hand, and 3 and 22a on the other hand, is the presence of a weak
interaction between the fluorine substituent of 4a and the Cε hydrogen of Lys-103 (Figure SI5, see Supporting
Information). A corresponding interaction is not found in 3 due to the fact that this compound does not contain a
fluorine atom at this position and that the corresponding pyrimidine nitrogen of 3 is located too far away from the
corresponding Cε hydrogen of Lys-103. Similarly, in 22a this fluorine atom is substituted with a hydrogen atom, bearing a
partially positive charge (Figure B, supporting information) and therefore incapable of forming a favorable electrostatic
interaction with the Cε hydrogen of Lys-103. These docking experiments corroborate the experimental findings, as the
differences in EC50 between the three molecules in question are comparatively small.
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Conclusions
In summary, we have developed a short and practical synthesis of new NNRTI, which are similar in structure to earlier
described di(arylamino)pyrimidines but feature a 2,6-disubstituted 3-fluoropyridine instead of a 2,4-disubstituted
pyrimidine moiety. The in vitro studies of a synthesized library confirmed a SAR similar to that observed earlier for the
di(arylamino)pyrimidines series, as well as for the recently published 3-aminopyridine derivatives.32 An important
observation is that the presence of a fluorine atom on the central pyridine ring is essential for the antiviral activity, both
against the wild type HIV and the drug-resistant mutant strains. The activity of the best molecules 4c,k was, for all
studied HIV strains, close to or slightly higher than that of a well-known NNRTI API 3.
Experimental part
Instrumentation and Chemicals. All reagents, chemicals and solvents were obtained from commercial sources and
used without extra purification unless stated otherwise. Melting points were determined on a Büchi apparatus and are
uncorrected. The 1H NMR and 13C NMR spectra were recorded in CDCl3, CD3COCD3, CD3OD or DMSO-d6 on a Bruker
Avance II 400 spectrometer with TMS as the internal standard. Coupling constants are given in Hertz and the chemical
shifts are given in ppm. For mass spectrometric analysis, samples were dissolved in CH3OH containing 0.1% formic acid
and diluted to a concentration of approximately 10−5 mol/L. Injections (1 μL) were directed to the mass spectrometer at a
flow rate of 5 μL/min (CH3OH and 0.1% formic acid), using a CapLC HPLC system (Waters-Micromass). High resolution
mass data were acquired on a Q-TOF 2 mass spectrometer (Waters-Micromass) equipped with a standard electrospray
ionisation (ESI) interface. Column chromatography was performed on Kieselgel 60 (ROCC SI 1721, 40-60 mm), or on an
automated chromatography system with silica flash cartridges (Grace). Purities of final compounds were determined with
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a UHPLC system based on MS and UV detection. A Waters Aquity UPLC system coupled to a Waters PDA detector and a
Waters Micromass ZQ ESI mass spectrometer was used. A Halo C18 fused core 2.7µm, 2.1mm × 30mm column was used.
Solvent A: water with 0.1% formic acid; solvent B: methanol with 0.1% formic acid. Method: 0.5 mL/min, 0.5 min 99% A,
1% B then in 5.6 min from 99% A, 1% B to 5% A, 95% B then 0.4min, 5% A, 95% B, then in 0.1min to 99% A, 1% B holding
this for 4.4min before the next analysis. The wavelength for UV detection was 254 nm. All final products had a purity of at
least 95%, with the exception of compounds 4r (94%), 4t (94%) and 18a (93%).
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Structural data. X-ray data were collected on a Bruker platform goniometer equipped with sealed Mo (λ= 0.71073 Å) X-
ray tube, pyrrolithic graphite monochromator, and Smart 1000 CCD detector. For data collection and reduction, the
Bruker SAINT software, V7.66A (Bruker Corporation, Madison, USA, 2010) was employed. Data were corrected for
absorption with the multi-scan method with SADABS 2008/1 (Bruker Corporation, Madison, USA, 2008). Structures were
solved with direct methods with SHELXS-97,33 and refined with SHELXL-2014/7 (George M. Sheldrick, Universität
Göttingen, 2014) and the shelXle graphical interface.34 CIF files were deposited at the CCDC, reference numbers: 1410424
(7), 1410427 (11a), 1410425 (4a), 1410426 (4b). Ellipsoid plots of all structures were made with ORTEP-3 for Windows35 and
can be found in the Supporting Information.
Biological Assays. Cells. The TZM-bl cell line (NIH AIDS Research and Reference Reagent Program, Germantown,
USA) was used for the evaluation of drug susceptibility and cytotoxicity. TZM-bl cells were cultured in Dulbecco’s
Minimum Essential Medium (DMEM) (Lonza) containing 10% heat-inactivated FBS and 50 µg gentamycin/mL at 37 °C in
a humidified 5% CO2, 95% air environment. Twice a week the cells were treated with 0.25% trypsin – 1 mM EDTA (Lonza)
for 10 minutes. The resulting cell suspension was washed with an equivalent amount of TZM-bl medium and subsequently
seeded in a T75 culture flask (Greiner Bio-One, Germany) at 106 cells in 20 mL medium.
Antiviral assay. The antiviral activity of the newly designed compounds was measured by pre-incubating 104 TZM-bl
cells (at 105 cells/mL in culture medium supplemented with 30µg/mL DEAE dextran) in a 96-well plate for 30 minutes at
37 °C, 5% CO2 in the presence or absence of serial dilutions of the each compound. Subsequently, 200 TCID50 of wild type
(Bal) or NNRTI-resistant HIV-1 (Y181C, L100I + K103N) was added to each well and cultures were incubated for 48 hours
before quantifying luciferase activity. Each condition was evaluated in triplicate wells and in at least three independent
experiments. The antiviral activity of the compound was expressed as the percentage of viral inhibition compared to the
untreated controls and subsequently plotted against the compound concentration. Non-linear regression analysis was
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used to calculate the 50% effective concentration (EC50) based on at least three independent measurements and using
GraphPad Prism version 5.03 for Windows (GraphPad Software, San Diego, CA, USA).
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WST-1 cytotoxicity assay. The Water Soluble Tetrazolium-1 (WST-1) Cell Proliferation Assay is a colorimetric assay for
the measurement of cell proliferation and viability. The assay is based on the cleavage of the tetrazolium salt WST-1 ((4-
[3-(4-iodophenyl)-2-(4-nitrophenyl)- 2H-5-tetrazolio]-1,3-benzene disulfonate)) to a formazan dye by a complex cellular
mechanism. This bioreduction is largely dependent on the glycolytic production of NAD(P)H in viable cells. Therefore,
the amount of formazan dye formed correlates directly to the number of viable cells in the culture, and can be quantified
by measuring the absorbance at 450nm in a multiwell plate reader. The greater the number of viable cells, the greater the
amount of formazan dye produced following the addition of WST-1. Cytotoxicity of each compound was evaluated using
this WST-1 viability assay, according to the manufacturer’s instructions (Roche, Vilvoorde, Belgium). Briefly, 104 TZM-bl
cells were seeded in a 96-well plate and cultured for 2 days in the presence of a serial dilution of each compound. After
48h exposure, Cell Proliferation Reagent was added and absorbance at 450 nm was quantified after 90 min using a
microplate reader (BioRad, Tokio, Japan). Each compound was tested in three replicate wells and in at least three
independent experiments. The percentage cell viability, compared to untreated controls, was plotted against the
compound concentration and non-linear regression analysis was performed using GraphPad Prism version 5.02 for
Windows (GraphPad Software, San Diego, CA, USA) to calculate the 50% cytotoxic concentration (CC50).
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Computational methods. Docking of 4a and 22a. The crystal structure of RT in complex with 313 was taken as the
starting structure and both compounds were positioned in the pocket by superimposing their aromatic ring atoms onto
the corresponding atoms of 3. Positions were refined by energy minimization of both ligand and protein using the
GROMOS 53A6 force-field36 within the Gromacs software suite31 and until the maximum force dropped below 10 kJ/mol.
Force-field parameters and atomic partial charges for 4a and 22a were generated with the online ATB tool (version 2.2).37
Electrostatic potential surface of 4a and 22a. The electrostatic potential surfaces of both compounds after geometry
optimization were calculated with Spartan 14 using Hartree-Fock 6-31G** basis set.38
Synthetic procedures.
4-[(3,6-Difluoropyridin-2-yl)amino]benzonitrile (7). To a solution of 4-aminobenzonitrile (0.156 g, 1.320 mmol) in
THF (4.5 mL) a solution of t-BuLi (1.6 M in pentane; 0.763 mL, 1.22 mmol) was added dropwise at –78 °C. Next, a solution
of 2,3,6-trifluoropyridine (0.266 g, 2.0 mmol) in THF (1.5 mL) was added and the mixture was stirred for 5 min at –78 °C.
The reaction mixture was warmed to room temperature and stirred for 2 h, then aq. NH4Cl (10 mL) was added and the
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mixture was extracted with EtOAc (2 x 20 mL). The combined organic fractions were dried over MgSO4, filtered and
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3
concentrated. The resulting oil was purified by column chromatography to give 7 as a white solid (128 mg, 46%); mp 120–
4
5
122 °C (CH2Cl2); 1H NMR (400 MHz, CDCl3):
δ
6.40 (ddd, J = 8.5 Hz, 3.3 Hz, 2.3 Hz, 1H), 6.86 (br, 1 H), 7.43 (ddd, J = 9.6
99.1 (dd, J = 40.8
6
7
8
Hz, 8.5 Hz, 6.1 Hz, 1H), 7.62 (d, J = 8.9 Hz, 2 H), 7.77 (d, J = 8.9 Hz, 2 H); 13C NMR (100 MHz, CDCl3):
δ
9
Hz, 3.6 Hz), 105.2, 118.4 (2 C), 119.2, 126.0 (dd, J = 19.1 Hz, 9.4 Hz), 133.5 (2 C), 141.6 (dd, J = 19.1 Hz, 9.4 Hz), 143.0, 144.2 (dd,
J =243.6 Hz, 5.4 Hz), 157.2 (d, J = 236.8 Hz). HRMS (ESI) m/z calcd. for C12H7F2N3 ([M+H]+): 231.0608, found: 231.0618.
Single crystals for XRD analysis were grown by the slow evaporation from a dichloromethane solution. CCDC Nr.
1410424.
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4-[(3,6-Difluoropyridin-2-yl)amino]-N-mesitylbenzimidamide (9). A mixture of nitrile 7 (0.231 g, 1.0 mmol),
MeSO3H (0.065 mL, 1.0 mmol) and 2,4,6-trimethylaniline (0.281 mL, 2 mmol) in N-methyl-2-pyrrolidinone (0.5 mL) was
placed in a 10 mL microwave vial and heated in the microwave oven (300 W output) for 1 h at 180 °C. The mixture was
cooled to room temperature, a solution of Na2CO3 (10% in H2O, 10 mL) was added and the mixture was extracted with
EtOAc (3 x 10 mL). The residue was purified by column chromatography to give 9 (33 mg, 9%) as a brownish solid; mp
>240 °C (dec). 1H NMR (400 MHz, CDCl3):
1H), 6.85 (s, 2 H), 6.88 (br, 1 H), 7.33 (ddd, J = 9.5 Hz, 8.5 Hz, 6.2 Hz, 1H), 7.64 (d, J = 8.9 Hz, 2 H), 7.84 (d, J = 8.9 Hz, 2 H);
13C NMR (100 MHz, CDCl3):
17.7 (2 C), 20.7, 97.5 (dd, J = 41.2 Hz, 3.4 Hz), 118.6 (2 C), 125.4 (dd, J = 18.1 Hz, 9.4 Hz), 127.7
δ 2.09 (s, 6H), 2.25 (s, 3H), 4.53 (br, 2 H), 6.26 (ddd, J = 8.5 Hz, 3.1 Hz, 2.4 Hz,
δ
(2 C), 128.77 (2 C), 128.84, 129.9, 131.9, 140.9 (2 C), 142.5 (dd, J = 18.1 Hz, 12.9 Hz), 143.7, 144.1 (dd, J =252.5 Hz, 5.5 Hz), 153.0,
157.3 (dd, J = 235.0 Hz, 1.5 Hz); HRMS (ESI) m/z calcd. for C21H21F2N4 ([M+H]+): 367.1734, found: 367.1720.
4-Bromo-2-fluoro-6-methylaniline (13c).39 A round bottomed flask was charged with 2-fluoro-6-methylaniline (12
mmol, 1.5 g) and acetic acid (20 mL). Bromine (12 mmol, 0.616 mL) was added dropwise, and the reaction mixture was
stirred for 2 h at room temperature. The reaction mixture was evaporated, neutralized with saturated aq. Na2CO3 solution,
and extracted with CH2Cl2 (3 x 50 mL). Combined organic phases were dried over Mg2SO4 and evaporated in vacuo. The
residue was purified with an automated chromatography system using Silica Flash Cartridges applying a heptane-ethyl
acetate gradient (from 100% heptane to 100% ethylacetate in 35 min, 35 mL/min). Obtained as red liquid; yield 82% (2.0
g); 1H NMR (400 MHz, CDCl3):
CDCl3): 17.4, 108.8 (d, J = 10.1 Hz), 116.7 (d, J = 23.1 Hz), 126.7 (d, J = 4.1 Hz), 128.8 (d, J = 2.9 Hz), 132.7 (d, J = 12.4 Hz), 151.8
(d, J = 240.5 Hz).
δ
2.16 (s, 3H), 3.63 (s, 2H), 6.98 (s, 1H), 7.02 (dd, J = 10.1 Hz, 2.1 Hz, 1H); 13C NMR (100 MHz,
δ
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4-Amino-3-fluoro-5-methylbenzonitrile (8c).40 A 50 mL round bottomed flask was charged with CuCN (2.95 mmol,
264 mg), CuI (0.25 mmol, 47 mg), KI (0.52 mmol, 86 mg), N,N'-dimethyl-1,2-ethanediamine (2.46 mmol, 217 mg), 4-
bromo-2-fluoro-6-methylaniline (2.45 mmol, 500 mg) and dry DMF (20 mL). The resulting mixture was heated to 110 °C
(oil bath temperature) for 16 h. After the reaction, DMF was evaporated and aqueous 28% NH3 solution (50 mL) was
added. The resulting mixture was extracted with dichloromethane, washed with brine solution and dried over MgSO4.
The product was purified with an automated chromatography system using Silica Flash Cartridges applying a heptane-
ethyl acetate gradient (from 100% heptane to 80% ethylacetate in 35 min, 35 mL/min). Obtained as white solid; yield 74%
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(0.272 g); mp 119–120 °C (AcOEt); 1H NMR (400 MHz, CDCl3):
δ
2.19 (s, 3H), 4.20 (brs, 2H), 7.10–7.16 (m, 2H); 13C NMR
(100 MHz, CDCl3): 17.0 (d, J = 3.1 Hz), 99.3 (d, J = 9.7 Hz), 116.7 (d, J = 22.0 Hz), 119.3 (d, J = 3.0 Hz), 124.6 (d, J = 4.2 Hz),
δ
130.2 (d, J = 2.4 Hz), 138.1 (d, J = 11.9 Hz), 149.8 ( d, J = 240.6 Hz).
General Procedure for synthesis of anilines 12a–f (General Procedure A): A solution of Pd catalyst in DMA was
prepared first. A flask was charged with Pd(OAc)2 (0.2 mmol, 45 mg) and tri(o-tolyl)phosphine (0.4 mmol, 0.122 g), dry
DMA (4 mL) was added and the resulting solution was stirred for 15 min under an argon atmosphere. Next, a 100 mL
round bottomed flask was charged with a 4-bromoaniline 9a–e (4 mmol), acrylonitrile (6.0 mmol, 0.32 g),
tetrabutylammonium chloride (4.0 mmol, 1.12 g) and CH3COONa·3H2O (4.0 mmol, 0.54 g). The freshly prepared Pd
catalyst solution was added, the resulting mixture was stirred for 2 min under an argon atmosphere, and then heated to
reflux (oil bath temperature 140 °C) for 48 h. The reaction mixture was allowed to cool down to room temperature and
filtered through Celite. The Celite cake was washed with toluene (100 mL), combined filtrates were washed with water
(100 mL), brine (50 mL), dried with MgSO4 and evaporated in vacuo. The residue was separated with an automated
chromatography system using Silica Flash Cartridges applying a heptane-ethyl acetate gradient (from 100% heptane to
80% ethylacetate in 35 min, 35 mL/min). Compounds 12a,41 12b,42 and 12d41 were reported earlier. Data for compounds
12c,e,f are given below.
3-(4-Amino-3-fluoro-5-methylphenyl)acrylonitrile (12c). Prepared according to the General Procedure A from
Pd(OAc)2 (0.16 mmol, 36 mg), tri(o-tolyl)phosphine (0.32 mmol, 97 mg), 4-bromo-2-fluoro-6-methylaniline (3.19 mmol,
0.65 g), acrylonitrile (4.78 mmol, 0.25 g), tetrabutylammonium chloride (3.19 mmol, 0.86 g) and AcONa·3H2O (3.19 mmol,
0.43 g). Obtained as a mixture of geometrical isomers (Z:E 1:3.13), light yellow solid; yield 89% (0.0.49 g); mp 98-100 °C
(AcOEt); 1H NMR (400 MHz, CDCl3): signals of major (E)-isomer:
δ 2.19 (s, 3H), 4.03 (brs, 2H), 5.60 (d, J = 16.5 Hz, 1H),
6.94 (s, 1H), 6.99 (dd, J = 11.4 Hz, 1.6 Hz, 1H), 7.19 (d, J = 16.5 Hz, 1H); signals of minor (Z)-isomer: δ 2.21 (s, 3H), 5.19 (d, J =
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12.1 Hz, 1H), 6.88 (d, J = 12.1 Hz, 1H), 7.29 (s, 1H), 7.47 (dd, J = 11.8 Hz, 1.6 Hz, 1H), signal of NH overlapped with the signal
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of major isomer; 13C NMR (100 MHz, CDCl3): signals of major (E)-isomer:
118.9, 123.2 (d, J = 7.7 Hz), 124.2 (d, J = 3.8 Hz), 125.9 (d, J = 2.0 Hz), 136.2 (d, J = 12.5 Hz), 149.9 (d, J = 2.8 Hz), 151.0 (d, J =
239.5 Hz); signals of minor (Z)-isomer: 90.7, 113.3 (d, J = 20.1 Hz), 118.1, 123.2 (d, J = 7.7 Hz), 123.9 (d, J = 3.9 Hz), 127.7 (d, J
δ 16.9 (d, J = 3.2 Hz), 92.3, 111.3 (d, J = 19.8 Hz),
δ
9
= 2.1 Hz), 136.1 (d, J = 12.5 Hz), 147.7 (d, J = 2.8 Hz), 150.6 (d, J = 239.2 Hz), signal of CH3 overlapped with the signal of
major isomer. HRMS (ESI) m/z calcd. for C10H10FN2 ([M+H]+): 177.0828, found: 177.0832.
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3-(4-Amino-3,5-difluorophenyl)acrylonitrile (12e). Prepared according to the General Procedure A from Pd(OAc)2
(0.25 mmol, 56 mg), tri(o-tolyl)phosphine (0.5 mmol, 152 mg), 4-bromo-2,6-difluoroaniline (5.0 mmol, 1.04 g),
acrylonitrile (7.5 mmol, 0.398 g), tetrabutylammonium chloride (5.0 mmol, 1.39 g) and AcONa·3H2O (5.0 mmol, 0.680 g).
Obtained as a mixture of geometrical isomers (Z:E 1:3.13), white solid; yield 69% (0.62 g); mp 173-174 °C (AcOEt); 1H NMR
(400 MHz, CDCl3): signals of major (E)-isomer:
7.18 (d, J = 16.5 Hz, 1H); signals of minor (Z)-isomer:
2.2 Hz, 2H); 13C NMR (100 MHz, CDCl3): signals of major (E)-isomer:
δ
4.09 (brs, 2H), 5.64 (d, J = 16.5 Hz, 1H), 6.95 (dd, J = 7.0 Hz, 2.2 Hz, 2H),
5.29 (d, J = 12.1 Hz, 1H), 6.87 (d, J = 12.1 Hz, 1H), 7.36 (dd, J = 7.3 Hz,
94.2, 110.3 (dd, J = 14.9 Hz, 7.4 Hz, 2 C), 118.2, 122.2
δ
δ
(t, J = 8.7 Hz), 127.1 (t, J = 16.4 Hz), 148.6 (t, J = 3.0 Hz), 151.4 (dd, J = 242.0 Hz, 8.5 Hz, 2 C); signals of minor (Z)-isomer:
92.6, 112.1 (dd, J = 15.2 Hz, 7.4 Hz, 2 C), 117.5, 146.5 (t, J = 3.0 Hz), 150.93 (dd, J = 241.3 Hz, 8.7 Hz, 2 C); other signals are
overlapped with signals of major isomer. HRMS (ESI) m/z calcd. for C9H7F2N2 ([M+H]+): 181.0577, found: 181.0574.
δ
(E)-Methyl 3-(4-amino-3,5-dimethylphenyl)acrylate (12f). Prepared according to the General Procedure A from
Pd(OAc)2 (0.2 mmol, 45 mg), tri(o-tolyl)phosphine (0.4 mmol, 122 mg), 4-bromo-2,6-dimethylaniline (4.0 mmol, 0.800 g),
methyl acrylate (6.0 mmol, 0.52 g), tetrabutylammonium chloride (4.0 mmol, 1.11 g) and AcONa·3H2O (4.0 mmol, 0.544
g). Analytical data correspond to those found in literature. White solid; yield 61% (0.49 g); mp 83-84 °C (AcOEt); 1H NMR
(400 MHz, CDCl3):
δ
2.17 (s, 3H), 3.77 (s, 3H), 3.86 (brs, 2H), 6.23 (d, J = 15.9 Hz, 1H), 7.14 (s, 2H), 7.57 (d, J = 15.9 Hz, 1H);
17.5 (2 C), 51.4, 112.8, 121.5 (2 C), 124.1, 128.8 (2 C), 145.4, 145.6, 168.2. HRMS (ESI) m/z calcd.
13C NMR (100 MHz, CDCl3):
δ
for C12H16NO2 ([M+H]+): 206.1181, found: 206.1188.
General Procedure B for the Synthesis of intermediates 11a–e. A solution of Pd catalyst in dioxane was prepared
first. A flask was charged with Pd(OAc)2 (0.025 mmol, 5.6 mg) and Xantphos (0.03 mmol, 17 mg), dry dioxane (5 mL) was
added and the resulting solution was stirred for 15 min under an argon atmosphere. Next, a 50 mL round bottomed flask
was charged with 2,6-dichloro-3-fluoropyridine (0.5 mmol, 83 mg), an aniline 2a–d or 8d (0.6 mmol) and t-BuONa (0.7
mmol, 67 mg). The freshly prepared solution of Pd catalyst was added, the resulting mixture was stirred for 2 min under
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an argon atmosphere, and then heated to reflux (oil bath temperature 110 °C) for 16 h. The reaction mixture was allowed
to cool down to room temperature and filtered through Celite. The Celite cake was washed with CH2Cl2 (100 mL),
combined organic phases were evaporated in vacuo. The residue was separated with an automated chromatography
system using Silica Flash Cartridges applying a heptane-ethyl acetate gradient (from 100% heptane to 100% ethylacetate in
35 min, 35 mL/min).
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4-[(6-Chloro-3-fluoropyridin-2-yl)amino]benzonitrile (11a). Prepared according to the General Procedure B from
Pd(OAc)2 (0.025 mmol, 5.61 mg), Xantphos (0.03 mmol, 17 mg), 2,6-dichloro-3-fluoropyridine (0.5 mmol, 83 mg), 4-
aminobenzonitrile (0.6 mmol, 71 mg) and t-BuONa (0.7 mmol, 67 mg). Obtained as white solid, yield 89% (0.11 g); mp 171–
172 °C (AcOEt); 1H NMR (400 MHz, CDCl3):
δ
6.83 (dd, J = 8.4 Hz, 2.8 Hz, 1H), 6.87 (brs, 1H), 7.31 (dd, J = 10.0 Hz, 8.4 Hz,
105.3, 115.5 (d, J = 3.2 Hz), 118.4 (2 C),
1H), 7.62 (d, J = 8.8 Hz, 2H), 7.77 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3):
δ
119.2, 124.2 (d, J = 18.0 Hz), 133.4 (2 C), 143.0, 143.1 (d, J = 3.5 Hz), 143.2 (d, J = 11.4 Hz), 146.0 (d, J= 253.6 Hz); HRMS (ESI)
m/z calcd. for C12H8ClFN3 ([M+H]+): 248.0391, found: 248.0397. Single crystals for XRD analysis were grown by the slow
evaporation from a dichloromethane solution. CCDC Nr. 1410427.
6-Chloro-N-(4-chlorophenyl)-3-fluoropyridin-2-amine (11b). Prepared according to the General Procedure B from
Pd(OAc)2 (0.30 mmol, 68 mg), Xantphos (0.36 mmol, 0.21 g), 2,6-dichloro-3-fluoropyridine (6.02 mmol, 1.0 g), 4-
chloroaniline (7.23 mmol, 0.92 g) and t-BuONa (8.43 mmol, 0.81 g). Obtained as white solid; yield 74% (1.12 g); mp 89–90
°C (AcOEt); 1H NMR (400 MHz, CDCl3):
δ
6.63 (brs, 1H), 6.74 (dd, J = 8.0 Hz, 2.7 Hz, 1H), 7.26 (dd, J = 10.0 Hz, 8.0 Hz, 1H),
113.9 (d, J = 3.2 Hz), 120.2 (2 C), 123.5 (d, J =
7.32 (d, J = 8.9 Hz, 2H), 7.61 (d, J = 8.9 Hz, 2H); 13C NMR (100 MHz, CDCl3):
δ
17.9 Hz), 127.7 (2 C), 129.0, 137.5, 142.9 (d, J = 3.5 Hz), 144.1 (d, J = 11.5 Hz), 145.7 (d, J = 252.6 Hz); HRMS (ESI) m/z calcd. for
C11H8Cl2FN2 ([M+H]+): 257.0049, found: 257.0038.
6-Chloro-3-fluoro-N-(4-fluorophenyl)pyridin-2-amine (11c). Prepared according to the General Procedure B from
Pd(OAc)2 (0.25 mmol, 56 mg), Xantphos (0.30 mmol, 0.17 g), 2,6-dichloro-3-fluoropyridine (5.0 mmol, 0.83 g), 4-
fluoroaniline (6.0 mmol, 0.58 mL) and t-BuONa (7.0 mmol, 0.67 g). Obtained as white solid; yield 88% (1.06 g); mp 87–88
°C (AcOEt); 1H NMR (400 MHz, CDCl3):
δ
6.56 (brs, 1H), 6.69 (dd, J = 8.2 Hz, 2.7 Hz, 1H), 7.06 (t, J = 9.1 Hz, 2H), 7.22 (dd, J
113.5 (d, J = 3.2 Hz), 115.7
= 10.2 Hz, 8.2 Hz, 1H), 7.58 (dd, J = 9.1 Hz, 4.7 Hz, 2H); 13C NMR (100 MHz, CDCl3+CD3COCD3):
δ
(d, J = 22.6 Hz, 2 C), 121.0 (d, J = 7.8 Hz, 2 C), 123.4 (d, J = 17.9 Hz), 134.9 (d, J = 2.6 Hz), 143.0 (d, J = 3.4 Hz), 144.6 (d, J = 11.7
Hz), 145.7 (d, J = 252.2 Hz), 158.7 (d, J = 242 Hz); HRMS (ESI) m/z calcd. forC11H8ClF2N2 ([M+H]+): 241.0344, found:
241.0335.
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Methyl 4-[(6-chloro-3-fluoropyridin-2-yl)amino]benzoate (11d). Prepared according to the General Procedure B
from Pd(OAc)2 (0.1 mmol, 22 mg), Xantphos (0.120 mmol, 0.069 g), 2,6-dichloro-3-fluoropyridine (2.0 mmol, 0.332 g),
methyl 4-aminobenzoate (2.0 mmol, 0.302 g) and Cs2CO3 (10.0 mmol, 3.26 g). white solid; yield 66% (0.367 g); mp 159–160
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δ
3.89 (s, 3H), 6.78 (dd, J = 8.2 Hz, 2.8 Hz, 1H), 6.83 (brs, 1H), 7.27 (dd, J = 8.2 Hz,
51.9, 114.8 (d, J = 2.9 Hz), 117.7 (2
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9.9 Hz, 1H), 7.71 (d, J = 8.8 Hz, 2H), 8.02 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3):
δ
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C), 123.8 (d, J = 18.0 Hz), 124.0, 131.0 (2 C), 143.0 (d, J = 3.6 Hz), 143.2, 143.6 (d, J = 11.3 Hz), 145.9 (d, J = 253.7 Hz), 166.8;
HRMS (ESI) m/z calcd. for C13H11ClFN2O2 ([M+H]+): 281.0493, found: 281.0497.
3-{4-[(6-Chloro-3-fluoropyridin-2-yl)amino]phenyl}acrylonitrile (11e). Prepared according to the General
Procedure B from Pd(OAc)2 (0.05 mmol, 11.0 mg), Xantphos (0.06 mmol, 34 mg), 2,6-dichloro-3-fluoropyridine (1.0 mmol,
166 mg), 3-(4-aminophenyl)acrylonitrile (1.0 mmol, 144 mg) and t-BuONa (1.4 mmol, 135 mg). Obtained as a mixture of
geometrical isomers (Z:E 1:9), light yellow solid; yield 74% (0.15 g); mp 169–170 °C (AcOEt); 1H NMR (400 MHz, CDCl3):
signals of major (E)-isomer:
8.2 Hz, 1H), 7.34 (d, J = 16.6 Hz, 1H), 7.44 (d, J = 8.7 Hz, 2H), 7.71 (d,J = 8.7 Hz, 2H); ); signals of minor (Z)-isomer:
J = 12.1 Hz, 1H), 7.05 (d, J = 12.1 Hz, 1H), 7.83 (d, J = 8.8 Hz, 2H); other signals are overlapped with signals of major isomer.
13C NMR (100 MHz, CDCl3): signals of major (E)-isomer:
93.8, 114.8 (d, J = 3.1 Hz), 118.67, 118.71 (2 C), 123.8 (d, J = 18.0 Hz),
δ
5.76 (d, J = 16.6 Hz, 1H), 6.78 (dd, J = 8.2 Hz, 2.8 Hz, 1H), 6.83 (brs, 1H), 7.28 (dd, J = 9.9 Hz,
δ
5.32 (d,
δ
127.9, 128.6 (2 C), 141.8, 143.0 (d, J = 3.5 Hz), 143.6 (d, J = 11.4 Hz), 145.9 (d, J = 252 Hz), 149.9; HRMS (ESI) m/z calcd. for
C14H10ClFN3 ([M+H]+): 274.0547, found: 274.0540.
4-[(2-Chloro-5-fluoropyrimidin-4-yl)amino]benzonitrile (17). Prepared according to the General Procedure B from
Pd(OAc)2 (0.25 mmol, 56 mg), Xantphos (0.3 mmol, 0.17 g), 2,4-dichloro-5-fluoropyrimidine (5 mmol, 0.84 g), 4-
aminobenzonitrile (5 mmol, 0.59 g) and Cs2CO3 (25 mmol, 0.84 g). Obtained as white solid; yield 75% (0.93 g); mp 235-236
°C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 7.12 (s, 1H), 7.69 (d, J = 8.8 Hz, 2H), 7.83 (d, J = 8.8 Hz, 2H), 8.18 (d, J = 2.5 Hz,
1H). 13C NMR (100 MHz, DMSO-d6): δ 106.0, 119.5, 121.3 (2 C), 133.5 (2 C), 142.9, 143.2 (d, J = 21.2 Hz), 145.9 (d, J = 260 Hz),
150.1 (d, J = 12.4 Hz), 153.1 (d, J = 3.5 Hz); HRMS (ESI) m/z calcd. for C11H7ClFN4 ([M+H]+): 249.0343, Found: 249.0341.
4-[(5-Chloro-2-fluorophenyl)amino]benzonitrile (21). Prepared according to the General Procedure B from
Pd(OAc)2 (0.025 mmol, 5.61 mg), Xantphos (0.03 mmol, 17 mg), 2-bromo-4-chloro-1-fluorobenzene (0.5 mmol, 110 mg), 4-
aminobenzonitrile (0.5 mmol, 59 mg) and t-BuONa (0.7 mmol, 67 mg). Obtained as white solid; yield 86% (107 mg); mp
141-142 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 6.04 (brs, 1H), 6.96 (ddd, J = 8.8 Hz, 4.3 Hz, 2.5 Hz, 1H), 7.00–7.10 (m,
3H), 7.35 (dd, J = 7.2 Hz, 2.5 Hz, 1H), 7.54 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3): δ 103.9, 116.5 (2 C), 117.0 (d, J =
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21.2 Hz), 119.3, 120.0 (d, J = 1.5 Hz), 123.2 (d, J = 7.4 Hz), 129.7 (d, J = 3.5 Hz), 129.9 (d, J = 12.7 Hz), 133.9 (2 C), 145.9, 152.7 (d,
J = 243.7 Hz); HRMS (ESI) m/z calcd. for C13H9ClFN2 ([M+H]+): 247.0438, found: 247.0432.
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4-[(6-Chloropyridin-2-yl)amino]benzonitrile (24). A solution of Pd catalyst in dioxane was prepared first. A flask
was charged with Pd(OAc)2 (0.1 mmol, 22 mg) and rac-BINAP (0.1 mmol, 62 mg), dry toluene (10 mL) was added and the
resulting solution was stirred for 15 min under an argon atmosphere. Next, a 100 mL round bottomed flask was charged
with 2,6-dichloropyridine (5 mmol, 0.74 g), 4-aminobenzonitrile (5 mmol, 0.71 g) and K2CO3 (0.1 mol, 13.8 g). The freshly
prepared Pd catalyst solution was added, the resulting mixture was stirred for 2 min under an argon atmosphere, and
then heated to reflux (oil bath temperature 120 °C) for 24 h. The mixture was allowed to cool down to room temperature
and filtered through Celite. Celite cake was washed with dichloromethane (100 mL), combined organic phases were
evaporated in vacuo and the residue was separated with an automated chromatography system using Silica Flash
Cartridges applying a heptane-ethyl acetate gradient (from 100% heptane to 100% ethylacetate in 35 min, 35 mL/min).
Obtained as white solid; yield 60% (0.28 g); mp 182-183 °C (AcOEt); 1H NMR (400 MHz, DMSOd6): δ 6.87 (d, J = 8.0 Hz,
1H), 6.91 (d, J = 8.0 Hz, 1H), 7.65 (t, J = 8.0 Hz, 1H), 7.69 (d, J= 8.9 Hz, 2H), 7.77 (d, J = 8.9 Hz, 2H), 9.85 (brs, 1H); 13C NMR
(100 MHz, DMSO-d6): δ 102.5, 110.9, 115.4, 118.1 (2 C), 120.0, 133.7 (2 C), 141.2, 145.5, 148.1, 155.1; HRMS (ESI) m/z calcd. for
C13H10ClN2 ([M+H]+): 229.0533, found: 229.0533.
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General Procedure C for the Synthesis of Compounds 4a–u. A solution of Pd catalyst in dioxane was prepared first.
A flask was charged with Pd(OAc)2 (0.025 mmol, 5.61 mg) and XPhos (0.03 mmol, 14 mg), dry dioxane (5 mL) was added
and the resulting solution was stirred for 15 min under an argon atmosphere. Next, a 50 mL round bottomed flask was
charged with the intermediate 7a–e (0.5 mmol, 124 mg), an aniline 8a–c or 12a–f or a phenol 15a,b (0.6 mmol) and Cs2CO3
(1.25 mmol, 0.41 g). The freshly prepared solution of Pd catalyst was added, the resulting mixture was stirred for 2 min
under an argon atmosphere, and then heated to reflux (oil bath temperature 110 °C) for 16 h. The mixture was allowed to
cool down to room temperature and filtered through Celite. Celite cake was washed with dichloromethane (100 mL),
combined organic phases were evaporated in vacuo and the residue separated with an automated chromatography system
using Silica Flash Cartridges applying a heptane-ethyl acetate gradient (from 100% heptane to 100% ethylacetate in 35
min, 35 mL/min).
4-{[6-(Mesitylamino)-3-fluoropyridin-2-yl]amino}benzonitrile (4a). Synthesized according to the general
procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a (0.5 mmol, 124 mg),
aniline 8a (0.6 mmol, 81 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as white solid; yield 53% (91 mg); mp 201–202 °C
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(AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.18 (s, 6H), 2.33 (s, 3H), 5.59 (dd, J = 8.6 Hz, 2.0 Hz, 1H), 5.72 (s, 1H), 6.69 (br, 1H),
6.94 (s, 2H), 7.09 (dd, J = 10.2 Hz, 8.6 Hz, 1H), 7.47 (d, J = 8.7 Hz, 2H), 7.64 (d, J = 8.7 Hz, 2H); 13C NMR (100 MHz, DMSO-
d6): δ 18.6, 21.0, 98.1 (br), 101.4, 118.2 (2 C), 120.2, 125.4 (d, J = 18.0 Hz), 129.0 (2 C), 132.8 (2 C), 135.1, 136.1, 136.4 (2 C), 140.0
(d, J = 240.0 Hz), 141.5 (d, J = 11.2 Hz), 146.1, 153.3; HRMS (ESI) m/z calcd. for C21H20FN4 ([M+H]+): 347.1672, found:
347.1688. HUPLC: tr 5.26 min. Single crystals for XRD analysis were grown by the slow evaporation of an acetone solution.
CCDC Nr. 1410425.
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4-{[6-(4-Cyanophenyl)amino-5-fluoropyridin-2-yl]amino}-3,5-dimethylbenzonitrile (4b). Synthesized according
to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a (0.5 mmol,
124 mg), aniline 8b (0.6 mmol, 88 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as white solid; yield 61% (109 mg); mp
235–236 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.27 (s, 6H), 5.70 (dd, J = 8.6 Hz, 2.2 Hz, 1H), 5.91 (s, 1H), 6.78 (brs, 1H),
7.19 (dd, J = 10.2 Hz, 8.6 Hz, 1H), 7.45 (s, 2H),7.49 (d, J = 8.9 Hz, 2H), 7.62 (d, J = 8.9 Hz, 2H); 13C NMR (100 MHz, CDCl3): δ
18.5, 97.6 (d, J = 2.5 Hz), 104.1, 109.7, 117.9 (2 C), 118.8, 119.4, 124.3 (d, J = 18.0 Hz), 132.2 (2 C), 133.1 (2 C), 137.1 (2 C), 141.4 (d, J
= 242.7 Hz), 141.8, 142.0 (d, J = 10.8 Hz), 143.9, 150.7 (d, J = 2.4 Hz); HRMS (ESI) m/z calcd. for C21H17FN5 ([M+H]+):
358.1468, found: 358.1486. HUPLC: tr 4.60 min. Single crystals for XRD analysis were grown by the slow evaporation from
an acetone solution. CCDC Nr. 1410426.
(E)-4-({6-[4-(2-Cyanovinyl)-2,6-dimethylphenylamino]-3-fluoropyridin-2-yl}amino)benzonitrile (4c).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11a (0.5 mmol, 124 mg), aniline 12a (0.6 mmol, 103 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as white
solid; yield 62% (0.119 g); mp 211-212 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.28 (s, 6H), 5.67 (dd, J = 8.6 Hz, 2.2 Hz,
1H), 5.86 (brs, 1H), 5.88 (d, J = 16.6 Hz, 1H), 6.75 (brs, 1H), 7.18 (dd, J = 10.2 Hz, 8.6 Hz, 1H), 7.26 (s, 2H), 7.39 (d, J = 16.6 Hz,
1H), 7.51 (d, J = 8.9 Hz, 2H), 7.67 (d, J = 8.9 Hz, 2H); 13C NMR (100 MHz, CD3COCD3): δ 18.9, 96.5, 99.2 (d, J = 2.0 Hz),
103.6, 118.9 (2 C), 119.4, 120.1, 125.5 (d, J = 18.2 Hz), 128.5 (2 C), 132.5, 133.4 (2 C), 138.0 (2 C), 141.4 (d, J = 240.8 Hz), 142.5,
142.7 (d, J = 11.2 Hz), 146.3, 151.2, 153.3 (d, J = 2.0 Hz); HRMS (ESI) m/z calcd. for C23H19FN5 ([M+H]+): 384.1624, found:
384.1629. HUPLC: tr 4.76 min.
(E)-Methyl 3-(4-{6-[(4-cyanophenyl)amino]-5-fluoropyridin-2-ylamino}-3,5-dimethyl-phenyl)acrylate (4d).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11a (0.5 mmol, 124 mg), aniline 12f (0.6 mmol, 123 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as white
solid; yield 71% (0.15 g); mp 189–190 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.25 (s, 6H), 3.82 (s, 3H), 5.68 (dd, J = 8.6
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Hz, 2.2 Hz, 1H), 5.86 (s, 1H), 6.43 (d, J = 16.0 Hz, 1H), 6.76 (d, J = 3.2 Hz, 1H), 7.15 (dd, J = 10.2 Hz, 8.6 Hz, 1H), 7.31 (s, 2H),
7.46 (d, J = 8.8 Hz, 2H), 7.64 (d, J = 8.9 Hz, 2H), 7.67 (d, J = 16.0 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 18.6 (2C), 51.8, 97.1
(d, J = 2.0 Hz), 103.7, 117.5, 117.8 (2 C), 119.6, 124.3 (d, J = 17.9 Hz), 128.3 (2 C), 132.4, 133.1 (2 C), 136.7 (2 C), 139.2, 141.0 (d, J =
10.8 Hz), 141.8 (d, J = 241.4 Hz), 144.1, 144.4, 151.5 (d, J = 2.0 Hz), 167.5; HRMS (ESI) m/z calcd. for C24H22FN4O2 ([M+H]+):
417.1727, found: 417.1732. HUPLC: tr 5.04 min.
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3-(4-{6-[(4-Fluorophenyl)amino]-5-fluoropyridin-2-ylamino}-3,5-dimethylphenyl)acrylo-nitrile (4e).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11c (0.5 mmol, 120 mg), aniline 12a (0.6 mmol, 103 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as a
mixture of geometrical isomers (Z:E 1:6.3), white solid; yield 66% (0.123 g); mp 189–190 °C (AcOEt); 1H NMR (400 MHz,
CDCl3): signals of major (E)-isomer: δ 2.24 (s, 6H), 5.51 (dd, J = 8.5 Hz, 2.1 Hz, 1H), 5.78 (brs, 1H), 5.84 (d, J = 16.6 Hz, 1H),
6.43 (brs, 1H), 6.90 (t, J = 8.8 Hz, 2H), 7.08 (dd, J = 10.4 Hz, 8.5 Hz, 1H), 7.21 (s, 2H), 7.35 (d, J = 16.6 Hz, 1H), 7.47 (dd, J =
9.1 Hz, 4.7 Hz, 2H); signals of minor (Z)-isomer: δ 5.39 (d, J = 12.1 Hz, 1H), 7.57 (s, 2H), other signals are overlapped with
signals of major isomer; 13C NMR (100 MHz, CDCl3) of major (E)-isomer: δ 18.6 (2C), 95.2 (d, J = 2.1 Hz), 95.5, 115.3 (d, J =
22.3 Hz, 2C), 118.4, 120.2 (d, J = 7.5 Hz, 2C), 123.5 (d, J = 17.5 Hz), 127.6 (2C), 131.1, 136.1 (d, J = 2.5 Hz), 136.8 (2 C), 140.6, 140.9
(d, J = 240.7 Hz), 143.3 (d, J = 11.1 Hz), 150.2, 151.1 (d, J = 2.2 Hz), 158.1 (d, J = 240.8 Hz); HRMS (ESI) m/z calcd. for
C22H19F2N4 ([M+H]+): 377.1578, found: 377.1585. HUPLC: tr 4.94 min, 5.03 min.
3-[4-(6-{4-[(2-Cyanovinyl)-2,6-dimethylphenyl]amino}-3-fluoropyridin-2-yl)aminophenyl]acrylonitrile (4f).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11e (0.5 mmol, 137 mg), aniline 12a (0.6 mmol, 103 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as a
mixture of geometrical isomers (Z,E:E,Z:E,E 1:1:14.7), yellow solid; yield 63% (0.129 g); mp 269–270 °C (AcOEt); 1H NMR
(400 MHz, CD3COCD3): signals of major (E,E)-isomer: δ 2.26 (s, 6H), 5.97 (d, J = 16.6 Hz, 1H), 6.02 (dd, J = 8.5 Hz, 2.0 Hz,
1H); 6.30 (d, J = 16.7 Hz, 1H), 7.30 (dd, J = 10.9 Hz, 8.5 Hz, 1H), 7.33 (d, J = 8.8 Hz, 2H), 7.41 (d, J = 16.6 Hz, 1H), 7.46-7.52 (m,
3H), 7.59 (d, J = 16.7 Hz, 1H), 7.68 (d, J = 8.8 Hz, 2H), 8.16 (brs, 1H); signals of minor (Z,E)- and (E,Z)-isomers: δ 5.47 (d, J =
12.1 Hz, 1H), 5.73 (d, J = 12.1 Hz, 1H), 6.25 (d, J = 16.6 Hz, 1H), 7.15 (d, J = 12.1 Hz, 1H), other signals are overlapped with
signals of major isomer; 13C NMR (100 MHz, CD3COCD3) of major (E,E)-isomer: δ 18.9, 93.3, 96.5, 101.0, 118.9, 119.0, 119.4,
119.7, 125.2 (d, J = 18.2 Hz), 127.3, 128.5, 129.1, 132.4, 138.0, 142.6, 145.0, 144.0 (d, J = 240.6 Hz), 151.0, 151.2, 153.3 (d, J = 1.8 Hz);
HRMS (ESI) m/z calcd. for C25H21FN5 ([M+H]+): 410.1781, found: 410.1793. HUPLC: tr 4.87 min, 4.92 min.
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4-{6-[(4-Fluorophenyl)amino]-5-fluoropyridin-2-ylamino}-3,5-dimethylbenzonitrile (4g). Synthesized according
to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg), intermediate 11c (0.5 mmol,
120 mg), aniline 8b (0.6 mmol, 88 mg), and Cs2CO3 (1.25 mmol, 408 mg). Obtained as colorless solid; yield 50% (88 mg);
mp 135-136 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.23 (s, 6H), 5.58 (dd, J = 8.4 Hz, 2.1 Hz, 1H), 5.86 (brs, 1H), 6.47 (brs,
1H), 6.91 (t, J = 8.7 Hz, 2H), 7.11 (dd, J = 10.4 Hz, 8.4 Hz, 1H), 7.39–7.45 (m, 4H); 13C NMR (100 MHz, CDCl3): δ 18.5 (2 C),
95.6 (d, J = 2.3 Hz), 109.1, 115.3 (d, J = 22.3 Hz, 2 C), 119.1, 120.2 (d, J = 7.5 Hz, 2 C), 123.5 (d, J = 18.2 Hz), 132.1 (2 C), 135.9 (d, J
= 2.5 Hz), 136.9(2 C), 141.1 (d, J = 241.6 Hz), 142.3, 143.3 (d, J = 11.1 Hz), 150.5 (d, J = 2.3 Hz), 158.1 (d, J = 241 Hz); HRMS (ESI)
m/z calcd. for C20H17F2N4 ([M+H]+): 351.1421, found: 351.1404. HUPLC: tr 4.89 min.
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4-{6-[4-(2-Cyanovinyl)phenylamino]-3-fluoropyridin-2-ylamino}benzonitrile (4h). Synthesized according to the
general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a (0.5 mmol, 124
mg), aniline 12d (0.6 mmol, 87 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as a mixture of geometrical isomers (Z:E
1:2.33), white solid; yield 68% (0.12 g); mp 285-286 °C (AcOEt); 1H NMR (400 MHz, DMSO-d6): signals of major (E)-isomer:
δ
6.22 (d, J = 16.6 Hz, 1H), 6.44-6.52 (m, 1H), 7.50-7.60 (m, 6H), 7.69 (d, J = 8.4 Hz, 2H), 7.84 (d, J = 8.4 Hz, 2H), 9.31 (s, 1H),
9.39 (s, 1H), signals of minor (Z)-isomer:
δ 5.60 (d, J = 12.0 Hz, 1H), 7.28 (d, J = 12.0 Hz, 1H), 7.62 (d, J = 8.6 Hz, 2H), 7.75 (d,
J = 8.6 Hz, 2H), 9.45 (s, 1H), other signals are overlapped with the signals of major (E)-isomer; 13C NMR (100 MHz, DMSO-
d6): signals of major (E)-isomer:
133.3 (2 C), 141.1 (d, J = 11.7 Hz), 141.9 (d, J = 244 Hz), 144.7, 145.6, 149.6 (d, J = 2.2 Hz), 150.8, 1 signal is missing because of
overlap; signals of minor (Z)-isomer: 91.2, 102.5, 119.1 (2 C), 119.2, 120.1, 126.2, 130.4 (2 C), 133.2 (2 C), 144.5, 148.9, other
δ 92.7, 102.4, 103.6 (br), 117.7 (2 C), 118.9 (2 C), 120.2, 125.7 (d, J = 18.1 Hz), 126.2, 129.3 (2 C),
δ
signals are overlapped with the signals of major isomer; HRMS (ESI) m/z calcd. for C21H15FN5 ([M+H]+): 356.1311, found:
356.1308. HUPLC: tr 4.60 min, 4.65 min.
4-[6-(4-Chlorophenyl)amino-5-fluoropyridin-2-ylamino]-3,5-dimethylbenzonitrile (4i). Synthesized according to
the general procedure C using Pd(OAc)2 (0.025 mmol, 5.1 mg), XPhos (0.03 mmol, 14 mg), intermediate 11b (0.5 mmol, 129
mg), aniline 8b (0.6 mmol, 88 mg), and Cs2CO3 (1.25 mmol, 408 mg). Obtained as colorless solid; yield 54% (99 mg); mp
197-198 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.25 (s, 6H), 5.60 (dd, J = 8.5 Hz, 2.1 Hz, 1H), 5.85 (brs, 1H), 6.52 (brs,
1H), 7.13 (dd, J = 10.4 Hz, 8.5 Hz, 1H), 7.17 (d, J = 8.8 Hz, 2H), 7.43 (s, 2H), 7.44 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz,
CDCl3): δ 18.5 (2 C), 96.0 (d, J = 2.3 Hz), 109.3, 119.0, 119.7 (2 C), 123.6 (d, J = 18.2 Hz), 126.7, 128.7 (2 C), 132.1 (2 C), 136.9 (2
C), 138.5, 141.2 (d, J = 241.9 Hz), 142.2, 143.0 (d, J = 11.0 Hz), 150.6 (d, J = 2.3 Hz); HRMS (ESI) m/z calcd. for C20H17ClFN4
([M+H]+): 367.1126, found: 367.1142. HUPLC: tr 5.16 min.
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3-{4-[6-(4-Chlorophenyl)amino-5-fluoropyridin-2-ylamino]-3,5-dimethylphenyl}acrylonitrile (4j). Synthesized
according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg), intermediate 11b
(0.5 mmol, 129 mg), aniline 12a (0.6 mmol, 103 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as a mixture of geometrical
isomers (Z:E 1:13.5), brown solid; yield 65% (128 mg); mp 156-157 °C (AcOEt); 1H NMR (400 MHz, CDCl3): signals of major
(E)-isomer: δ 2.23 (s, 6H), 5.56 (dd, J =8.5 Hz, 2.1 Hz, 1H), 5.83 (d, J = 16.6 Hz, 1H), 5.84 (brs, 1H), 6.50 (brs, 1H), 7.09 (dd, J
= 10.4 Hz, 8.5 Hz, 1H), 7.13 (d, J = 8.9 Hz, 2H), 7.21 (s, 2H), 7.34 (d, J = 16.6 Hz, 1H), 7.45 (d, J = 8.9 Hz, 2H); signals of minor
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(Z)-isomer: δ
5.42 (d, J = 12.1 Hz, 1H), 7.60 (s, 2H); 13C NMR (100 MHz, CDCl3): δ 18.5 (2 C), 95.4, 95.6 (d, J = 2.2 Hz), 118.4,
119.6 (2 C), 123.6 (d, J = 17.8 Hz), 126.3, 128.2 (2 C), 129.0 (2 C), 131.1, 136.7 (2 C), 138.6, 140.4, 140.9 (d, J = 241.0 Hz), 142.8 (d, J
= 11.0 Hz), 150.1, 151.1 (d, J = 2.2 Hz); HRMS (ESI) m/z calcd. for C22H19ClFN4 ([M+H]+): 393.1282, found: 393.1296. HUPLC: tr
5.24 min.
(E)-4-{6-[4-(2-Cyanovinyl)-2-fluoro-6-methylphenylamino]-3-fluoropyridin-2-ylamino}benzonitrile (4k).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.6 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11a (0.5 mmol, 124 mg), aniline 12c (0.6 mmol, 110 mg) and Cs2CO3 (1.25 mmol, 408 mg). Obtained as brown
solid; yield 79% (150 mg); mp 235-236 °C (AcOEt); 1H NMR (400 MHz, CD3COCD3): δ 2.29 (s, 3H), 6.26 (dd, J = 8.6 Hz, 2.2
Hz, 1H), 6.34 (d, J = 16.4 Hz, 1H), 7.33-7.38 (m, 1H), 7.37 (d, J = 8.8 Hz, 2H), 7.45-7.48 (m, 2H), 7.59 (d, J = 16.6 Hz, 1H), 7.68
(br s, 1H), 7.75 (d, J = 8.8 Hz, 2H), 8.32 (brs, 1H); 13C NMR (100 MHz, CD3COCD3): δ 17.5, 96.9, 99.5 (d, J = 2.0 Hz), 102.9,
111.8 (d, J = 22.5 Hz), 117.9, 118.1 (2 C), 119.1, 124.5 (d, J = 18.3 Hz), 125.8 (d, J = 2.7 Hz), 130.4 (d, J = 13.1 Hz), 131.8 (d, J = 8.6
Hz), 132.5 (2 C), 138.2 (d, J = 2.0 Hz), 141.1 (d, J = 242.1 Hz), 141.7 (d, J = 11.4 Hz), 145.2, 149.1 (d, J = 2.7 Hz), 151.5 (d, J = 2.1
Hz), 158.5 (d, J = 245.2 Hz); HRMS (ESI) m/z calcd. for C22H16F2N5 ([M+H]+): 388.1374, found: 388.1368. HUPLC: tr 4.55 min.
4-[3-Fluoro-6-(p-tolyloxy)pyridin-2-ylamino]benzonitrile (4l). Synthesized according to the general procedure C
using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a (0.5 mmol, 124 mg), phenol 15a (0.6
mmol, 65 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as white solid; yield 89% (0.142 g); mp 153-154 °C (AcOEt); 1H
NMR (400 MHz, CDCl3): δ 2.46 (s, 3H), 6.41 (dd, J = 8.5 Hz, 2.0 Hz, 1H), 6.76 (brs, 1H), 7.06 (d, J = 8.4 Hz, 2H), 7.25 (d, J =
8.4 Hz, 2H), 7.36 (d, J = 8.6 Hz, 2H), 7.38 (m, 1H), 7.42 (d, J = 8.6 Hz, 2H); 13C NMR (100 MHz, CDCl3): δ 21.2, 101.0 (d, J =
2.9 Hz), 104.2, 118.0 (2 C), 119.7, 122.1 (2 C), 125.5 (d, J = 18.9 Hz), 130.3 (2 C), 133.2 (2 C), 134.8, 141.1 (d, J = 11.8 Hz), 142.7 (d, J
= 244.8 Hz), 143.7, 152.3, 158.4 (d, J = 1.8 Hz); HRMS (ESI) m/z calcd. for C19H15FN3O ([M+H]+): 320.1199, found: 320.1197.
HUPLC: tr 5.23 min.
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4-[3-Fluoro-6-(mesityloxy)pyridin-2-ylamino]benzonitrile (4m). Synthesized according to the general procedure C
using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a (0.5 mmol, 124 mg), phenol 15b (0.6
mmol, 82 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as yellow solid; yield 43% (0.074 g); mp 201-202 °C (AcOEt); 1H
NMR (400 MHz, CDCl3): δ 2.08 (s, 6H), 2.38 (s, 3H), 6.39 (dd, J = 8.4 Hz, 2.2 Hz, 1H), 6.70 (brs, 1H), 6.95 (s, 2H), 7.28 (s,
4H), 7.36 (dd, J = 10 Hz, 8.4 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 16.4 (2 C), 20.9, 99.6 (d, J = 2.8 Hz), 103.8, 117.6 (2 C),
119.6, 125.5 (d, J = 18.1 Hz), 129.2 (2 C), 131.0 (2 C), 132.9 (2 C), 134.6, 140.9 (d, J = 11.7 Hz), 142.1 (d, J = 244 Hz), 143.6, 148.9,
157.3 (d, J = 1.4 Hz); HRMS (ESI) m/z calcd. for C21H19FN3O ([M+H]+): 348.1512, found: 348.1509. HUPLC: tr 5.61 min.
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(E)-3-{4-[6-(4-Chlorophenyl)amino-5-fluoropyridin-2-ylamino]-3-methylphenyl}acrylonitrile (4n). Synthesized
according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11b
(0.5 mmol, 129 mg), aniline 12b (0.6 mmol, 95 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as yellow solid; yield 73%
(0.137 g); mp 189-190 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.30 (s, 3H), 5.74 (d, J = 16.6 Hz, 1H), 6.16 (brs, 1H), 6.24
(dd, J = 8.4 Hz, 2.2 Hz, 1H), 6.54 (brs, 1H), 7.19-7.29 (m, 5H), 7.32 (d, J = 16.6 Hz, 1H), 7.53 (d, J = 8.8 Hz, 2H), 7.67 (d, J = 8.4
Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 18.0, 93.1, 99.4 (d, J = 2.4 Hz), 118.8, 118.9, 120.5 (2 C), 123.6 (d, J = 17.9 Hz), 126.3,
127.13, 127.17, 127.4, 128.8 (2 C), 129.9, 138.1, 141.7 (d, J = 243.3 Hz), 142.3, 143.0 (d, J = 18.1 Hz), 148.7 (d, J = 2.7 Hz), 150.1;
HRMS (ESI) m/z calcd. for C21H1735ClFN4 ([M+H]+): 379.1126, found: 379.1109. HUPLC: tr 4.65 min.
(E)-Methyl 3-{4-[6-(4-fluorophenyl)amino-5-fluoropyridin-2-ylamino]-3,5-dimethylphenyl}acrylate (4o).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11c (0.5 mmol, 120 mg), aniline 12f (0.6 mmol, 123 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as brown
solid; yield 55% (0.113 g); mp 162-163 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.24 (s, 6H), 3.82 (s, 3H), 5.51 (dd, J = 8.5
Hz, 2.1 Hz, 1H), 5.77 (s, 1H), 6.42 (d, J = 16.0 Hz, 1H), 6.43 (brs, 1H), 6.92 (t, J = 8.8 Hz, 2H), 7.07 (dd, J = 10.5 Hz, 8.5 Hz,
1H), 7.30 (s, 2H), 7.49 (dd, J = 9.1 Hz, 4.7 Hz, 2H), 7.66 (d, J = 16.0 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 18.6 (2 C), 51.7,
95.0 (d, J = 2.2 Hz), 115.3 (d, J = 22.3 Hz, 2 C), 117.2, 120.1 (d, J = 7.4 Hz, 2 C), 123.5 (d, J = 17.6 Hz), 128.3 (2 C), 132.1, 136.0
(br), 136.6 (2 C), 139.5, 140.8 (d, J = 240.2 Hz), 143.2 (d, J = 11.2 Hz), 144.5 (2 C), 151.3 (br), 158.0 (d, J = 240.6 Hz), 167.5;
HRMS (ESI) m/z calcd. for C23H22F2N3O2 ([M+H]+): 410.1680, found: 410.1686. HUPLC: tr 5.36 min.
(E)-Methyl 3-{4-[6-(4-chlorophenyl)amino-5-fluoropyridin-2-ylamino]-3,5-dimethylphenyl}acrylate (4p).
Synthesized according to the general procedure C using Pd(OAc)2 (0.018 mmol, 4.10 mg), XPhos (0.022 mmol, 10.46 mg),
intermediate 11b (0.366 mmol, 94 mg), aniline 12f (0.44 mmol, 90 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as brown
solid; yield 71% (0.067 g); mp 162-163 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.24 (s, 6H), 3.82 (s, 3H), 5.53 (dd, J = 8.6
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Hz, 2.1 Hz, 1H), 5.77 (brs, 1H), 6.42 (d, J = 16.0 Hz, 1H), 6.48 (brs, 1H), 7.09 (dd, J = 10.5 Hz, 8.5 Hz, 1H), 7.17 (d, J = 8.9 Hz,
2H), 7.30 (s, 2H), 7.49 (d, J = 8.9 Hz, 2H), 7.66 (d, J = 16.0 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 18.6, 51.7, 95.4 (d, J = 2.1
Hz), 117.3, 119.6 (2 C), 123.6 (d, J = 17.9 Hz), 126.4, 128.3 (2 C), 128.7 (2 C), 132.1, 136.6 (2 C), 138.6, 139.4, 140.9 (d, J = 234.7
Hz), 142.8 (d, J = 11.0 Hz), 144.5, 151.4 (d, J = 2.0 Hz), 167.5; HRMS (ESI) m/z calcd. for C23H2235ClFN3O2 ([M+H]+): 426.1385,
found: 426.1383. HUPLC: tr 5.52 min.
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(E)-3-(4-{5-Fluoro-6-[4-(fluorophenyl)amino]pyridin-2-ylamino}-3-methylphenyl)acrylonitrile (4q). Synthesized
according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11c
(0.5 mmol, 120 mg), aniline 12b (0.6 mmol, 95 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as yellow solid; yield 75%
(0.135 g); mp 150-151 °C (AcOEt); 1H NMR (400 MHz, CDCl3): δ 2.29 (s, 3H), 5.72 (d, J = 16.6 Hz, 1H), 6.16 (brs, 1H), 6.21 (dd,
J = 8.4 Hz, 2.2 Hz, 1H), 6.48 (brs, 1H), 7.00 (t, J = 8.7 Hz, 2H), 7.19-7.28 (m, 3H), 7.31 (d, J = 16.6 Hz, 1H), 7.50-7.53 (dd, J =
9.0 Hz, 4.7 Hz, 2H), 7.69 (d, J = 8.4 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 18.0, 93.1, 99.1 (d, J = 2.3 Hz), 115.4 (d, J = 22.4
Hz, 2 C), 118.7, 118.9, 121.4 (d, J = 7.7 Hz, 2 C), 123.5 (d, J = 17.8 Hz), 126.4, 127.1, 127.2, 129.9, 135.6 (d, J = 2.6 Hz), 141.6 (d, J =
243.8 Hz), 142.4, 143.5 (d, J = 11.2 Hz), 148.8 (d, J = 2.7 Hz), 150.2, 158.5 (d, J = 241.6 Hz); HRMS (ESI) m/z calcd. for
C21H17F2N4 ([M+H]+): 363.1421, found: 363.1424. HUPLC: tr 5.02 min.
4-{6-[4-(2-Cyanovinyl)-2-methylphenylamino]-3-fluoropyridin-2-ylamino}benzonitrile (4r). Synthesized
according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a
(0.5 mmol, 124 mg), aniline 12b (0.6 mmol, 0.95 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as mixture of geometrical
isomers (Z:E 1:6.9), yellow solid; yield 70% (0.13 g); mp 239-240 °C (AcOEt); 1H NMR (400 MHz, CD3COCD3): signals of
major (E)-isomer:
Hz, 1H), 7.49-7.59 (m, 5H), 7.71 (d, J = 8.4 Hz, 1H), 7.84 (d, J = 8.8 Hz, 2H), 8.29 (s, 1H), 9.20 (s, 1H); signals of minor (Z)-
isomer:
5.68 (d, J = 12.0 Hz, 1H), 7.31 (d, J = 12.0 Hz, 1H), 8.35 (s, 1H); 13C NMR (100 MHz, CD3COCD3): signals of major
δ 2.26 (s, 3H), 6.29 (d, J = 16.6 Hz, 1H), 6.50 (dd, J = 8.6 Hz, J = 2.2 Hz, 1H), 7.46 (dd, J = 8.4 Hz, J = 1.9
δ
(E)-isomer: δ 17.4, 93.5, 101.7 (d, J = 2.5 Hz), 103.3, 118.5 (2 C), 118.7, 119.1, 121.1, 124.5 (d, J = 18.2 Hz), 126.1, 128.1, 129.9, 132.7 (2
C), 141.5 (d, J = 243.6 Hz), 141.6 (d, J = 11.3 Hz), 142.6, 145.1, 148.2, 150.1, 150.3 (d, J = 2.5 Hz); signals of minor (Z)-isomer: 17.5,
91.9, 118.4, 120.9, 121.0, 127.4, 129.4, 131.5, other signals are overlapped with signals of major isomer. HRMS (ESI) m/z calcd.
for C22H17FN5 ([M+H]+): 370.1468, found: 370.1455. HUPLC: tr 4.69 min, 4.75 min.
4-[6-(4-Cyanophenyl)amino-5-fluoropyridin-2-ylamino]-3-fluoro-5-methylbenzonitrile (4s). Synthesized
according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a
(0.5 mmol, 124), aniline 8c (0.6 mmol, 90 mg), and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as brown solid; yield 42% (75
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Journal of Medicinal Chemistry
mg); mp 253-254 °C (AcOEt); 1H NMR (400 MHz, CD3COCD3): δ 2.36 (s, 3H), 6.38 (dd, J = 8.6 Hz, 2.2 Hz, 1H), 7.43 (dd, J =
10.7, 8.6 Hz, 1H), 7.47 (d, J = 8.8 Hz, 2H), 7.63-7.67 (m, 2H), 7.76 (d, J = 8.8 Hz, 2H), 7.93 (s, 1H), 8.44 (s, 1H); 13C NMR (100
MHz, CD3COCD3): δ 17.4 (d, J = 2.6 Hz), 100.2 (d, J = 2.3 Hz), 103.1, 108.2 (d, J = 10.3 Hz), 117.1 (d, J = 25.1 Hz), 117.7 (d, J = 3.0
Hz), 118.1 (2 C), 119.1, 124.6 (d, J = 18.3 Hz), 130.1 (d, J = 3.2 Hz), 132.5, 133.2 (d, J = 12.3 Hz), 138.6 (d, J = 2.3 Hz), 141.5 (d, J =
242.3 Hz), 141.7 (d, J = 11.6 Hz), 145.0, 150.8 (d, J = 2.2 Hz), 157.5 (d, J = 247.3 Hz); HRMS (ESI) m/z calcd. for C20H14F2N5
([M+H]+): 362.1217, found: 362.1233. HUPLC: tr 4.46 min.
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4-{6-[4-(2-Cyanovinyl)-2,6-difluorophenylamino]-3-fluoropyridin-2-ylamino}benzonitrile (4t). Synthesized
according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg), intermediate 11a
(0.5 mmol, 124 mg), aniline 12e (0.6 mmol, 108 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as mixture of geometrical
isomers (Z:E 1:6.9), brown solid; yield 72% (140 mg); mp 223-224 °C (AcOEt); 1H NMR (400 MHz, CD3COCD3), signals of
major (E)-isomer: δ 6.38-6.44 (m, 2H), 7.38-7.46 (m, 3H), 7.51 (d, J = 8.8 Hz, 2H), 7.62 (d, J = 16.7 Hz, 1H), 7.79 (d, J = 8.8
Hz, 2H), 7.96 (brs, 1H), 8.38 (brs, 1H); signals of minor (Z)-isomer δ 5.87 (d, J = 12.1 Hz, 1H), 7.68 (d, J = 9.0 Hz, 2H), 8.01
(brs, 1H), other signals are overlapped with signals of major isomer; 13C NMR (100 MHz, CD3COCD3) signals of major (E)-
isomer: δ 99.0, 101.5 (d, J = 2.2 Hz), 104.0, 111.9 (dd, J = 18.5, J = 6.8 Hz), 118.7, 119.0 (2 C), 120.1, 121.9 (t, J = 16.3 Hz), 125.5 (d, J
= 18.3 Hz), 132.0 (t, J = 9.7 Hz), 133.5 (2 C), 142.6 (d, J = 243.2 Hz), 142.7 (d, J = 11.6 Hz), 145.9, 149.0 (t, J = 2.8 Hz), 151.0 (d, J
= 2.2 Hz), 158.6 (dd, J = 247.2 Hz, J = 6.5 Hz). HRMS (ESI) m/z calcd. for C21H13F3N5 ([M+H]+): 392.1123, found: 392.1127.
HUPLC: tr 4.35 min, 4.42 min.
(E)-Methyl 4-{6-[4-(2-cyanovinyl)-2,6-dimethylphenylamino]-3-fluoropyridin-2-ylamino}benzoate (4u).
Synthesized according to the general procedure C using Pd(OAc)2 (0.025 mmol, 5.61 mg), XPhos (0.03 mmol, 14 mg),
intermediate 11d (0.5 mmol, 140 mg), aniline 12a (0.6 mmol, 103 mg) and Cs2CO3 (1.25 mmol, 0.41 g). Obtained as white
solid; yield 72% (0.149 g); mp 233-234 °C (AcOEt); 1H NMR (400 MHz, CD3COCD3): δ 2.23 (s, 6H), 3.81 (s, 3H), 6.05 (dd, J =
8.5 Hz, 2.0 Hz, 1H), 6.27 (d, J = 16.7 Hz, 1H), 7.27 (dd, J = 10.8 Hz, 8.5 Hz, 1H), 7.45 (brs, 1H), 7.47 (s, 2H), 7.56 (d, J = 16.7
Hz, 1H), 7.61 (d, J = 9.2 Hz, 2H), 7.65 (d, J = 9.2 Hz, 2H), 8.14 (brs, 1H); 13C NMR (100 MHz, CD3COCD3): δ 17.9 (2 C), 51.0,
95.6, 97.8 (d, J = 2.0 Hz), 117.2 (2 C), 118.4, 121.9, 124.3 (d, J = 18.2 Hz), 127.5 (2 C), 130.0 (2 C), 131.5, 137.1 (2 C), 140.6 (d, J =
240.9 Hz), 141.7, 142.1 (d, J = 10.8 Hz), 145.5, 150.2, 152.3 (d, J = 1.9 Hz), 166.1; HRMS (ESI) m/z calcd. for C24H22FN4O2
([M+H]+): 417.1727, found: 417.1732. HUPLC: tr 4.96 min.
General Procedure D for the Synthesis of Compounds 18a,b. Same as the General Procedure C but starting from
the intermediate 17 (0.5 mmol, 124 mg), and an aniline 8b or 12a (0.6 mmol).
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