Preliminary SAR and biological evaluation of potent HIV-1 protease inhibitors with pyrimidine bases as novel P2 ligands to enhance activity against DRV-resistant HIV-1 variants

Article abstract of DOI:10.1016/j.ejmech.2019.111866

Introducing pyrimidine bases, the basic components of nucleic acid, to P2 ligands might enhance the potency of Human Immunodeficiency Virus-1 (HIV-1) protease inhibitors because of the carbonyl and amino groups promoting the formation of extensive hydrogen bonding interactions. In this work, we provide evidence that inhibitor 10e, with N-2-(2,4-Dioxo-3,4-dihydropyrimidin-1(2H)-yl) acetamide as the P2 ligand and a 4-methoxylphenylsulfonamide as the P2′ ligand, displayed remarkable enzyme inhibitory and antiviral activity, with the IC₅₀ 2.53 nM in vitro and a promising inhibition ratio with 68% against wild-type HIV-1 in vivo, with low cytotoxicity. This inhibitor also exhibited appreciable antiviral activity against DRV-resistant HIV-1 variants, which was of great value for further study.

Full text of DOI:10.1016/j.ejmech.2019.111866

Journal Pre-proof
Preliminary SAR and biological evaluation of potent HIV-1 protease inhibitors with
pyrimidine bases as novel P2 ligands to enhance activity against DRV-resistant HIV-1
variants
Mei Zhu, Ling Ma, Huiyu Zhou, Biao Dong, Yujia Wang, Zhen Wang, Jinming Zhou,
Guoning Zhang, Juxian Wang, Chen Liang, Shan Cen, Yucheng Wang
PII:
S0223-5234(19)31018-9
DOI:
https://doi.org/10.1016/j.ejmech.2019.111866
EJMECH 111866
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 28 November 2018
Revised Date: 7 November 2019
Accepted Date: 7 November 2019
Please cite this article as: M. Zhu, L. Ma, H. Zhou, B. Dong, Y. Wang, Z. Wang, J. Zhou, G. Zhang,
J. Wang, C. Liang, S. Cen, Y. Wang, Preliminary SAR and biological evaluation of potent HIV-1
protease inhibitors with pyrimidine bases as novel P2 ligands to enhance activity against DRV-
resistant HIV-1 variants, European Journal of Medicinal Chemistry (2019), doi: https://doi.org/10.1016/
j.ejmech.2019.111866.
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Preliminary SAR and biological evaluation of potent HIV-1 protease
inhibitors with pyrimidine bases as novel P2 ligands to enhance
activity against DRV-resistant HIV-1 variants
a
a
a
a
b
Mei Zhu , Ling Ma , Huiyu Zhou a, Biao Dong , Yujia Wang , Zhen Wang ,
a
a
a
b
Jinming Zhou , Guoning Zhang , Juxian Wang , Chen Liang , Shan Cen a, *, and
Yucheng Wang a, **
a
Institute of Medicinal Biotechnology, Chinese Academy of Medical Science and
Peking Union Medical College, Beijing 100050, China
b Lady Davis Institute for Medical Research and McGill AIDS Centre, Jewish General
Hospital, Montreal, Quebec, Canada
ABSTRACT: Introducing pyrimidine bases, the basic components of nucleic acid, to
P2 ligands might enhance the potency of Human Immunodeficiency Virus-1 (HIV-1)
protease inhibitors because of the carbonyl and amino groups promoting the
formation of extensive hydrogen bonding interactions. In this work, we provide
evidence that inhibitor 10e, with N-2-(2,4-Dioxo-3,4-dihydropyrimidin-1(2H)-yl)
acetamide as the P2 ligand and a 4-methoxylphenylsulfonamide as the P2' ligand,
displayed remarkable enzyme inhibitory and antiviral activity, with the IC50 2.53 nM
in vitro and a promising inhibition ratio with 68% against wild-type HIV-1 in vivo,
with low cytotoxicity. This inhibitor also exhibited appreciable antiviral activity
against DRV-resistant HIV-1 variants, which was of great value for further study.
Keywords: HIV-1 protease inhibitors, pyrimidine bases, antiviral activity,
DRV-resistant HIV-1 variants
Corresponding Author.
*Phone: +86 10 63037279. Fax: +86 10 63037279. E-mail: shancen@hotmail.com.(S Cen)
*Phone: +86 10 63165263. Fax: +86 10 63165263. E-mail: wangyucheng@imb.pumc.edu.cn.(Y Wang)

1. Introduction
The appearance of HIV-1 protease inhibitors (HIV-1 PIs) in the mid-1990’s and
their combination with reverse transcriptase inhibitors marked the beginning of highly
active antiretroviral therapy (HAART), which had dramatically reduced the mortality
and morbidity rates of HIV/AIDS [1-4]. However, there still exist severe problems,
such as the emergence of extensively cross-resistant strains of HIV-1, as well as
adverse effects [5-7]. In addition, protease inhibitors regimens suffer from a number
of other drawbacks including high pill burden, poor ADMET properties, and so on [8].
Even worse, the most egregious issue is the growing emergence of drug-resistant
strains of HIV which has rendered the long-term therapy options. Moreover, the
newest PI, Darunavir (DRV), with the highest bioavailability, has emerged highly
DRV-resistant HIV-1 variants. Up to now, more than ten HIV-1 protease mutations
associated with DRV resistance have been identified in highly treatment-experienced
patients; notably, the virologic efficacy of DRV was compromised in the presence of
three or more of these mutations [9, 10].
To address the growing problem of PI resistance, great effort has been made to
discover new compounds through modification of proved PIs including DRV. Some

of these PIs displayed remarkable enzyme inhibitory in the low nanomolar range (32
− 0.027 nM) and exhibited excellent antiviral activity against a panel of
multidrug-resistant HIV-1 variants in recent studies [11-18]. For instance, the
representative PIs that mainly contains a new P2 ligands in DRV (Figure 1) exhibits
potent activity against several HIV-1 isolates resistant to ATV, LPV or APV.
However, none of them was found to effectively inhibit DRV-resistant HIV-1 variants
R
[19, 20]. In particular, these PIs failed to block the replication of HIV-1DRV P51 that is
highly resistant to most PIs found thus far. Hence, there is an urgent need for novel
PIs with high genetic barrier against multidrug-resistant HIV-1 variants, especially
against DRV-resistant HIV-1 variants.
Figure 1. Antiviral activity of protease inhibitors against highly DRV-resistant HIV-1 variants.
In an effort to explore potent inhibitors active on resistant strains especially on
DRV-resistant HIV-1 variants and optimize ligand-binding site interactions in the
active site of HIV-1 protease, we introduced pyrimidine bases with flexible
heterocyclic moieties, as well as carbonyl and/or amino groups as the P2 ligands
instead of the bis-THF structural template in the lead compound DRV (see in Figure
2), aiming at increasing enzyme inhibitory in vivo on the one hand, as nucleobases
represent an important kind of kinetophore which might affect the absorption and
improve the bioavailability when they were introduced into the new designed

compounds [21, 22]. On the other hand, according to the strategy to overcome drug
resistance through increasing interactions between inhibitors and PR, carbonyl and/or
amino groups involved in newly introduced P2 moieties can promote extensive
hydrogen bonding interactions involved directly or water-mediated with the backbone
amino groups of residues Asp29 and Asp30 of PR in the corresponding S2 subsite [13,
23-27]. Herein, we report our studies on pyrimidine bases-derived protease inhibitors
in design, synthesis, and biological evaluation. A number of inhibitors displayed
potent enzyme inhibitor activity.
Figure 2. Design and general structure of target molecules.
2. Results and discussion
2.1.Chemistry
The syntheses of intermediates of substituted 4-amino-2-oxopyrimidin-1(2H)-yl)
acetic acids 2a-c and 2, 4-dioxopyrimidin-1(2H)-yl acetic acids 2e-h are outlined in

Scheme 1. Acids 2a-c were synthesized directly by saponification undergoing a
two-step one-pot reaction after the N-alkylation of 1a-c with ethyl bromoacetate in
43-65% yields [28]. N-Alkylation of 1e-h with ethyl bromoacetate proceeded using
potassium carbonate as the base in anhydrous DMF to give corresponding esters 3e-h
in 30-60% yields. Subsequent saponification was finished by sodium hydroxide to
give acetic acids 2e-h in yields of 61-75%.
H2N
Rb
N
O
H2N
Rb
N
O
1a, 2a: Rb = H;
a
O
1b 2b: Rb = CH3;
,
N
NH
OH
1c, 2c: Rb = F
1a- c
2a- c
H
H
H
1e, 3e and 2e: Rb = H;
1f, 3f and 2f: Rb = CH3;
1g, 3g and 2g: Rb = F;
O
N
O
O
N
O
O
N
O
c
O
b
O
N
N
Rb
OH
NH
1e- h
Rb
O
Rb
1h, 3h and 2h: Rb = CH2OH
2e- h
3e - h
Scheme 1. Syntheses of Substituted 2-(4-amino-2-oxopyrimidin-1(2H)-yl)acetic Acids and
Substituted 2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic Acids 2a-h. Reagents and
conditions: (a) (i) Ethyl bromoacetate, K2CO3, anhydrous DMF, Argon, r.t, overnight; (ii) NaOH,
H2O, r.t, 1 h; (iii) 4 M HCl, 0 °C, 0.5 h; (b) Ethyl bromoacetate, K2CO3, anhydrous DMF, Argon,
r.t, overnight; (c) (i) NaOH, H2O, r.t, 1 h; (ii) 4 M HCl, 0 °C, 0.5 h.
Compounds 8-9 were prepared from the commercially available material (2S,
3S)-1,2-epoxy-3-(boc-amino)-4-phenylbutane (4), as reported in the literature and
shown in Scheme 2 [29, 30].
Scheme 2. Syntheses of Amines 8-9. Reagents and conditions: (d) i-BuNH2, CH3CN, 80 °C, 6 h;

(e) Aryl sulfonyl chloride, DIEA, DMAP(Cat.), THF, 0 °C ~ r.t, 3-5 h; (f) CH2Cl2-CF3COOH
(1:1), 0 °C~r.t, 3 h.
The syntheses of inhibitors 10-12 shown in Scheme 3 were carried out by coupling
acids 2a-h with amines 8-9 under an EDCI/HOBt/DMAP-mediated coupling method.
The inhibitors 12a-h were obtained from 11a-h by refluxing with ammonium
formate and 10% Pd/C [31]. The inhibitor structures are shown in Scheme 3.
Scheme 3. Syntheses of Inhibitors 10-12. Reagents and conditions: (g) EDCI, HOBt, DMAP,
anhydrous DMF, Argon, 0 °C~r.t, 3 h; (h) HCOONH4, 10% Pd/C, CH3OH, reflux, 1 h.
2.2. Structure activity relationships
The inhibitory activity of the synthetic compounds against HIV-1 wild-type
protease was evaluated in vitro using a fluorescence resonance energy transfer (FRET)
method [32, 33]. The enzyme inhibitory of these compounds was compared to
clinically available PI, DRV. Pyrimidine bases as the P2 ligands were investigated in
combination with other phenylsulfonamide substituents as the P2' ligands in the
protease S2' subsite. The inhibitors with pyrimidine base amine-acetamide P2 ligands

showed impressive activities of nanomolar inhibitory potency. In particular,
compounds 10e, 10f, 10g, 10h and 10a displayed the most potent inhibitory activities
(IC50 = 1.95-9.07 nM).
These inhibitors exhibited nanomolar inhibitory potency as shown in Tables 1 and
2. Moreover, the activity of 2,4-dioxopyrimidin-1(2H)-yl derivatives with more
oxygen atoms as shown in Table 2 is usually superior to that of the
4-amino-2-oxopyrimidin-1 (2H)-yl) derivatives in Table 1. This consideration
suggests that the uracil moiety of 2,4-dioxopyrimidin-1(2H)-yl derivatives as P2
ligands can make more additional interactions with the backbone atoms and residues
through oxygen atoms (supporting by the docking in Figure 4), which is similar to the
cyclic ether (S)-THF or bis-THF scaffolds as P2 ligands reported by Ghosh et al [14].
Similarly, phenylsulfonamide derivatives with 4-methoxy (10a-h) and 4-amino
(12a-h) groups displayed generally higher potency than the corresponding substituted
compounds with 4-nitro (11a-h) groups. The P2' oxygen atom of methoxyl could
form hydrogen bonds (O…H-N) with the main-chain amide of Asp30' in the protease
S2' subsite, similar to inhibitors GRL-0489A [21], TMC-126 [21], GRL-0467 [6] and
GRL-0519A [25]. Moreover, the strong electron-withdrawing group 4-nitro would
reduce the electron density of not only the oxygen atom itself via inductive effects but
also the oxygen atom on the sulfonyl group via conjugative effects, reducing the
ability of hydrogen to bond with the amide of Asp30' (phenyl-Oinh…N-H) [13, 14, 23]
or water-mediated interactions with the amide of Ile50' (SO2inh…H2O…N-H) in the
generally conserved protease S2' subsite.
Table 1. Enzymatic Inhibitory Activities and Cytotoxicity of Inhibitors with Pyrimidine Base
Amine-acetamide P2 Ligands (1)
Compd.
Ra
Rb
Rc
IC50(nM) a
CC50(µM) a

10a
11a
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
H
H
H
OMe
NO2
NH2
OMe
NO2
NH2
OMe
NO2
NH2
OMe
NO2
NH2
-
9.04 ± 2.72
411.3 ± 65.9
153.2 ± 14.6
147 ± 57.2
＞100
＞100
＞100
＞100
＞100
＞100
＞100
＞100
＞100
＞100
＞100
＞100
＞100
12a
H
10b
11b
12b
10c
Me
Me
Me
F
1191 ± 472.9
375.4 ± 79.1
36.03 ± 10.37
482.1 ± 167.4
104.8 ± 17.4
10.35 ± 2.45
245 ± 96.4
11c
F
12c
F
10d
11d
12d
DRV*
H
H
H
H
H
126.1 ± 37.2
-
-
1.12 ± 0.59
a All assays were conducted in triplicate, and the data shown represent mean values (±1 standard deviation)
derived from the results of three independent experiments.
Table 2. Enzymatic Inhibitory Activities and Cytotoxicity of Inhibitors with Pyrimidine Base
Amine-acetamide P2 Ligands (2)
Compd.
10e
Rb
H
Rc
IC50(nM) a
2.53 ± 0.42
20.06 ± 7.50
CC50(µM) a
＞100
OMe
NO2
11e
H
＞100

12e
10f
H
NH2
OMe
NO2
NH2
OMe
NO2
NH2
OMe
NO2
NH2
-
20.07 ± 2.09
2.78 ± 0.63
44.31 ± 14.71
19.65 ± 4.03
1.95 ± 0.32
27.64 ± 9.44
16.28 ± 2.80
9.07 ± 1.87
405.3 ± 28.2
240.6 ± 36.7
1.12 ± 0.59
＞100
＞100
＞100
＞100
＞100
32.14
8.80
Me
11f
Me
12f
Me
10g
11g
12g
10h
11h
12h
DRV
F
F
F
CH2OH
CH2OH
CH2OH
-
＞100
＞100
＞100
＞100
a All assays were conducted in triplicate, and the data shown represent mean values (±1 standard deviation)
derived from the results of three independent experiments.
2.3.HIV-1 infectivity assay
On the basis of these results above, selected inhibitors were further evaluated using
a single-round infection assay with HIV-1 pseudotyped with vesicular stomatitis virus
G protein (VSVg). In the assay, virus-producing cells were treated with the
compounds, and the infectivity of the resultant virus was determined [34]. Notably,
the most active compounds 10e and 10g were equipotent as the reference compound
DRV. It is noteworthy that although equipotent in biochemical assays in vitro,
inhibitors of uracil analogues are more active in cell-based assays than that of
cytosine analogues (10h vs 10a), as shown in Table 3 and Figure 3.
Table 3. Enzymatic Inhibitory Activities and Inhibition of Inhibitors with Pyrimidine Base
Amine-acetamide P2 Ligands
Compd.
IC50(nM) a
Inhibition b
Compd.
IC50(nM) a
Inhibition b

(%) (10 µM)
(%) (10 µM)
10e
11e
12e
10d
10f
12f
10g
2.53±0.42
20.06±7.50
20.07±2.09
10.35±2.45
2.78±0.63
19.65±4.03
1.95±0.32
80.99
11g
12g
27.64 ± 9.44
16.28 ± 2.80
9.04 ± 2.72
9.07 ± 1.87
1.12 ± 0.59
-
32.76
51.03
48.43
50.27
72.69
53.99
83.23
62.98
33.22
59.77
83.21
0
10a
10h
DRV
DMSO
a All assays were conducted in triplicate, and the data shown represent mean values (±1 standard deviation)
derived from the results of three independent experiments.
b All assays were conducted in quadruplicate.
100
80
60
40
20
0
Inhibitors
Figure 3. Inhibition of Inhibitors with Pyrimidine Base Amine-acetamide P2 Ligands.
In order to better evaluate the newly identified uracil isosteres, an in vivo infection
assay with wild-type HIV-1 was performed. Notably, inhibitors 10e and 10g exhibited
a promising inhibition ratio against wild-type HIV-1 at a concentration of 100 nM in
vivo, with values of 68% and 51%, respectively, as shown in Figure 4 [35]. It is
noteworthy that compound 10e exhibited active antiviral inhibition if compared with

the reference compound Nevirapine (NVP) with 77% inhibition (the two compounds
were tested with other kinds of compounds together, so Nevirapine was chosen as the
positive control drug), which might be a potent HIV-1 inhibitor worthy for in-depth
study.
B
A
80
Compd. Inhibition(%) (100 nM)
60
10e
10g
68
51
76
0
40
20
0
NVPa
DMSO
Compounds
Figure 4. Inhibition Ratio against Wild-type HIV-1 of Compounds in vivo. a The two compounds
were tested with other kinds of compounds together, so Nevirapine (NVP) was chosen as the
positive control drug.
2.4 Antiviral activity against DRV-resistant HIV-1 variants
We next investigated if these compounds are able to overcome drug resistance
through increasing interactions between inhibitors and PR. Four amino acid
substitutions (V32I, L33F, I54M, and I84V) in HIV-1 PR were reported previously to
confer high-level resistance to DRV [10], and were introduced into pNL4-3-E-R-
R
(pHIV-1NL4-3), resulting in DRV-resistant HIV-1 proviral DNA pHIV-1DRV S. The
compounds 10e, 10f and 10g were tested for antiviral activity against DRV-sensitive
or resistant pseudotyped HIV-1 using a single-round infection assay. As shown in
Table 4 and Figure 5, the compounds 10e, 10f and 10g exhibited similar potency
against DRV-sensitive or resistant HIV-1 in a dose-response assay, and DRV-resistant
mutations only cause 1-2 fold increase in EC50. However, more than 16 fold increase

in EC50 was observed for mutated virus treated with DRV compared with that of wild
type virus. This suggests the ability of these compounds to overcome DRV resistance
and a broad prospect for further study.
Table 4. Antiviral Activity of 10e, 10f and 10g against Multidrug Resistant HIV-1 Variants
mean EC50 µM ± SD a
HIV-1NL4−3
fold resistanceb
Compd.
10e
HIVDRVRs
0.59 ± 0.11
2.87 ± 0.42
2.70 ± 0.36
0.10 ± 0.010
0.27±0.09
2.50±0.67
1.07±0.21
0.006±0.004
2.19
1.15
10f
10g
2.52
DRV
16.67
a All assays were conducted in triplicate, and the data shown represent mean values (±1 standard deviation)
derived from the results of three independent experiments.
b Fold resistance is defined by EC50(mutant)/EC50(WT)
.
Figure 5. Antiviral Activity of 10e, 10f and 10g against Multidrug Resistant HIV-1 Variants.
(A-D) Dose-response of compounds DRV, 10e, 10f and 10g against wild type HIV-1 and
DRV-resistant mutant. (E) Fold resistance is defined by EC50(mutant)/EC50(WT)
.
2.5. Molecular docking
The common mode of inhibitory binding was explored through molecular docking

using a HIV PR crystal structure (PDB-ID: 4mc9) [36]. Remarkably, the inhibitor 10e
fits perfectly into the PR binding site and several hydrogen-bonding interactions are
possible between the residues Asp29, Gly48, IleA50 and IleB50, as well as van der Waals
interactions with the outer enzyme atoms, both of which might account for the
promising HIV-1 PR inhibitory activity (Figure 6). Also as can be seen, the uracil
moiety of 2,4-dioxopyrimidin-1(2H)-yl derivative in compound 10e could produce
interactions with the PR active site via the two oxygen atoms, and this could account
for why inhibitors of uracil analogues exhibited higher potency than that of cytosine
analogues, which contain only one oxygen atom.
Figure 6. Docking of inhibitor 10e in HIV-1 PR. Ligand exposures are represented as purple
spheres. Amino acid side chains important for the ligand binding are depicted as blue arrows.
2.6.Correlation for 2,4-dioxo-3,4-dihydropyrimidine analogues
Further validation was achieved by correlation of the SAR of docked inhibitors 10e,
12e, 11f, 12f, 16q, 11g, 12g and 10h, as shown in Figure 7. The correlation observed
between these two sets of IC50 data (expt vs calcd, correlation coefficiency = 0.78)
supports our docking model with a common mode of binding as a valid platform for
PR inhibitor design.

Correlation for 2,4-Dioxo-3,4-dihydropyrimidine
analogues as HIV PR
-11
-12
-13
R2 = 0.7763
-14
-15
-2.0
-1.5
-1.0
-0.5
0.0
-PR log(1/IC50) (exp)
Figure 7. Strong correlation of docked 2,4-Dioxo-3,4-dihydropyrimidine analogues supports a
common mode of binding for HIV PR
3. Conclusion
We have designed, synthesized, and evaluated a series of inhibitors containing the
pyrimidine base moiety as the P2 ligand. Inhibitor 10e incorporating
N-2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide as the P2 ligand and
4-methoxyphenylsulfonamide isostere as the P2' ligand displayed remarkable enzyme
inhibitory and antiviral activity: 10e exhibited the closest enzyme inhibitory potency
(IC50 = 2.53 nM) and inhibition of infectivity in single round infection assay
comparable to DRV, as well as a promising inhibition ratio against wild-type HIV-1
in vivo (68% inhibition) and an appreciable antiviral activity against DRV-resistant
HIV-1 variants. SAR studies indicated that carbonyl and amino groups, as well as
flexible heterocyclic moieties in the introduced P2 ligand, were critical to the ligand’s
high enzyme affinity. Both P2 and P2' ligands were involved in hydrogen bonding
interactions with the backbone of both S2 and S2' subsites.
Furthermore, nucleobases represent an important kind of kinetophore, which might
be in favor of enhancing cell membrance permeability and improving the
bioavailability when they were introduced into the new designed compounds,
deserving further study.

4. Experimental section
4.1. Chemistry
All experiments requiring anhydrous conditions were conducted in flame-dried
glassware fitted with rubber septa under a positive pressure of dry argon, unless
otherwise noted. THF was distilled under argon from sodium-benzophenone ketyl and
CH2Cl2 was distilled under argon from calcium hydride. All reactions were monitored
by thin-layer chromatography on silica gel plates (GF-254) and visualized with the
UV light. Flash column chromatography was performed on a CombiFlash®Rf 200
system employing silica gel (50-75 µm, Qingdao Haiyang Chemical Co.,Ltd). Melting
points were taken on MP70 Melting Point System with revised. High resolution mass
1
spectra were obtained on an Autospee Ultima-TOF spectrometer. H NMR and 13C
NMR spectra were recorded in CDCl3, CD3OD, (CD3)2CO or DMSO-d6 on a Bruker
AVANCE III 400 MHz, 500 MHz or 600 MHz spectrometer (Bruker Inc) with
tetramethylsilane (TMS) as an internal reference. The chemical shifts are given in δ
1
13
(ppm) referenced to the respective solvent peak (CDCl3: H, δ = 7.26 ppm, C, δ =
1
13
1
77.16 ppm; CD3OD: H, δ = 3.31 ppm, C, δ = 49.00 ppm; (CD3)2CO: H, δ = 2.05
13
1
13
ppm, C, δ = 30, 205 ppm; DMSO-d6: H, δ = 2.49 ppm, C, δ = 39.5 ppm), and
coupling constants are reported in Hz. All the target compounds were characterized
by 1H and 13C NMRs and HRMS spectra.
4.1.1. 2-(4-Amino-2-oxopyrimidin-1(2H)-yl)acetic acid (2a)
To a dry flask was added cytosine (1a, 0.22 g, 2.0 mmol), K2CO3 ( 0.55 g, 4.0
mmol) and anhydrous DMF (3 mL). The mixture was stirred vigorously under an
argon atmosphere at room temperature for 1 hour, and then ethyl bromoacetate (0.27
mL, 2.4 mmol) was added dropwise via syringe and stirred overnight. Sodium
hydroxide (0.24 g, 6.0 mmol) dissolved in 5 mL water was added dropwise to the
reaction mixture and stirred for 1 hour at room temperature, which was then cooled to
0 °C to acidified to pH 4.0 with 4 M HCl (aqueous) and stirred additional 0.5 hour.
The precipitate separated out was isolated by filtration and dried, in vacuo, over P2O5

to give 2a as brown powder: yield 0.22 g (65%); mp319-321 °C; The powder wasn’t
dissolved in any deuterated solvents; LC-MS (ESI) [M + H]+ m/z 170.4.
4.1.2. 2-(4-Amino-5-methyl-2-oxopyrimidin-1(2H)-yl)acetic acid (2b)
The title compound was obtained from 5-methyl cytosine (1b) in 43% yield as pink
powder as described for 2a: mp315-318 °C; The powder wasn’t dissolved in any
deuterated solvents; LC-MS (ESI) [M - H]- m/z 182.4.
4.1.3. 2-(4-Amino-5-fluoro-2-oxopyrimidin-1(2H)-yl)acetic acid (2c)
The title compound was obtained from 5-fluorocytosine (1c) in 63% yield as white
powder as described for 2a: mp303-305 °C; The powder wasn’t dissolved in any
deuterated solvents; LC-MS (ESI) [M - H]- m/z 186.4.
4.1.4. Ethyl 2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetate (3e)
To a dry flask was added uracil (1e, 0.56 g, 5.0 mmol), K2CO3 ( 1.38 g, 10.0 mmol)
and anhydrous DMF (6 mL). The mixture was stirred vigorously under an argon
atmosphere at room temperature for 1 hour, and then ethyl bromoacetate (0.67 mL,
6.0 mmol) was added dropwise via syringe and stirred overnight. Water (10 mL) was
added to the residue and extracted with ethyl acetate (3 × 10 mL). The combined
organic phases were dried over Na2SO4, and removed under reduced pressure. Silica
gel column chromatography (hexanes/ethyl acetate, 2: 1, v: v) afforded the product as
1
white acicular crystal: yield 0.38 g (38%); mp118-120 °C; H NMR (500 MHz,
CD3OD) δ 7.56 (d, J = 8.0 Hz, 1H), 5.71 (d, J = 8.0 Hz, 1H), 4.55 (s, 2H), 4.26 (q, J =
13
7.0 Hz, 2H), 1.31 (t, J = 7.0 Hz, 3H); C NMR (126 MHz, CH3OD) δ 168.1, 165.3,
151.4, 146.0, 101.1, 61.6, 48.7, 13.0; LC-MS (ESI) [M + H]+ m/z 199.3.
4.1.5. Ethyl 2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetate (3f)
This compound was prepared analogously to 3e from thymine (1f) in 60% yield as
white powder: mp 138-140 °C; 1H NMR (500 MHz, CD3OD) δ 7.38 (s, 1H), 4.49 (d,
13
J = 8.0 Hz, 2H), 4.22 (q, J = 7.0 Hz, 2H), 1.87 (s, 3H), 1.28 (t, J = 7.0 Hz, 3H); C

NMR (151 MHz, CD3OD) δ 169.8, 167.0, 153.1, 143.3, 111.4, 63.0, 50.0, 14.5, 12.3;
LC-MS (ESI) [M + H]+ m/z 213.4.
4.1.6. Ethyl 2-(5-fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetate (3g)
This compound was prepared analogously to 3e from 5-fluorouracil (1g) in 40% yield
as white acicular crystal: mp 149-151 °C; 1H NMR (500 MHz, CD3OD) δ 7.85 (d, J =
6.0 Hz, 1H), 4.53 (s, 2H), 4.28 (q, J = 7.0 Hz, 2H), 1.33 (t, J = 7.0 Hz, 3H); 13C NMR
(151 MHz, CD3OD) δ 169.5, 160.0, 159.8, 151.6, 142.5, 140.9, 131.5, 131.3, 63.1,
50.1, 14.5; LC-MS (ESI) [M + H]+ m/z 217.4.
4.1.7. Ethyl 2-(5-hydroxymethyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetate
(3h)
This compound was prepared analogously to 3e from 5-hydroxy methyl uracil (1h)
1
in 30% yield as white powder: mp 156-158 °C; H NMR (500 MHz, CD3OD) δ 7.59
(s, 1H), 4.59 (s, 2H), 4.38 (s, 2H), 4.28 (q, J = 7.0 Hz, 2H), 1.34 (t, J = 7.0 Hz, 3H);
13C NMR (126 MHz, CH3OD) δ 168.21 (s), 164.18 (s), 151.43 (s), 142.77 (s), 113.79
(s), 61.55 (s), 56.29 (s), 48.76 (s), 13.00 (s); LC-MS (ESI) [M - H]- m/z 227.5.
4.1.8. 2-(2,4-Dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic acid (2e)
Sodium hydroxide (0.12 g, 3.0 mmol) dissolved in 2 mL water was added dropwise
to the flask contained ethyl 2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetate (3e,
0.20 g, 1.0 mmol). The reaction mixture was stirred for 1 hour at room temperature
and then cooled to 0 °C. The solution was acidified to pH 4.0 with 4 M HCl (aqueous)
and stirred for another 0.5 hour at 0 °C. The precipitate was isolated by filtration and
dried, in vacuo, over P2O5 to give 2e as white powder: yield 0.10 g (61%);
mp296-301 °C; The powder wasn’t dissolved in any deuterated solvents; LC-MS (ESI)
[M - H]- m/z 169.4.
4.1.9. 2-(5-Methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic acid (2f)
The title compound was obtained from 3f in 64% yield as white powder as

described for 2e: mp270-272 °C; The powder wasn’t dissolved in any deuterated
solvents; LC-MS (ESI) [M - H]- m/z 183.4.
4.1.10. 2-(5-Fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic acid (2g)
The title compound was obtained from 3g in 69% yield as white powder as
described for 2e: mp264-266 °C; The powder wasn’t dissolved in any deuterated
solvents; LC-MS (ESI) [M - H]- m/z 187.4.
4.1.11. 2-(5-(Hydroxymethyl)-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic acid
(2h)
The title compound was obtained from 3h in 75% yield as white powder as
described for 2e: mp195-198 °C; The powder wasn’t dissolved in any deuterated
solvents; LC-MS (ESI) [M - H]- m/z 199.4.
4.1.12. 2-(4-Amino-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-
methoxyphenylsulfonamido)-1-phenylbutan-2-yl)acetamide (10a)
N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDCI, 0.29 g,
1.5 mmol) and 1-hydroxybenzotriazole (HOBt, 0.15 g, 1.1 mmol) were sequentially
added in batches to a stirring solution of 2-(4-amino-2-oxopyrimidin-1(2H)-yl)acetic
acid
(2a,
0.17
g,
1.0
mmol)
and
N-((2R,3S)-3-amino-2-hydroxy-4-phenylbutyl)-N-isobutyl-4-
methoxybenzenesulfonamide (8, 0.43 g, 1.05 mmol) in dry DMF (3 mL) at 0 °C
under an argon atmosphere. The reaction mixture was stirred for 10 min at 0 °C and
then additional 1 hour at room temperature. 4-Dimethylaminopyridine (DMAP, 0.024
g, 0.20 mmol) was added and the reaction mixture was stirred for another 2 hours at
room temperature. The solvent was removed under reduced pressure. Water (6 mL)
was added to the residue and extracted with ethyl acetate (3 × 6 mL). The combined
organic layers were dried over Na2SO4, and evaporated, in vacuo. The residue was
purified by chromatography on a silica gel column (30 × 6 cm). Elution with 1:3 to
1:4 hexanes-ethyl acetate gave 10a as colorless oil: yield 0.17 g (30%);

mp185-187 °C; 1H NMR (500 MHz, CD3OD) δ 7.81 (d, J = 8.5 Hz, 2H), 7.32 (t, J =
7.5 Hz, 4H), 7.30 (d, J = 4.5 Hz, 1H), 7.26-7.20 (m, 1H), 7.12 (d, J = 8.5 Hz, 2H),
5.84 (d, J = 6.0 Hz, 1H), 4.49 ((d, J = 16.0 Hz, 1H), 4.21 (d, J = 16.0 Hz, 1H),
4.16-4.11 (m, 1H), 3.91 (s, 3H), 3.49 (d, J = 16.0 Hz, 1H), 3.39 (d, J = 16.0 Hz, 1H),
3.20-3.16 (m, 1H), 3.08-3.02 (m, 2H), 2.92-2.88 (m, 1H), 2.77-2.72 (m, 1H),
13
2.06-2.01(m, 1H), 0.95 (d, J = 6.5 Hz, 3H), 0.90 (d, J = 6.5 Hz, 3H); C NMR (101
MHz, CD3OD) δ 169.6, 168.2, 164.5, 158.9, 147.8, 140.0, 132.1, 130.7, 130.5, 129.4,
127.3, 115.4, 95.7, 73.5, 58.9, 56.2, 55.8, 54.0, 52.4, 36.3, 28.1, 20.6, 20.5; HRMS
(ESI) m/z calcd. for C27H35N5O6S ([M - H]-): 556.2224, found 556.2211.
4.1.13.
2-(4-Amino-5-methyl-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobutyl-
4-methoxyphenylsulfonamido)-1-phenylbutan-2-yl)acetamide (10b)
The title compound was obtained by 2b which was coupled with 8 through
EDCI/HOBt/DMAP coupling procedure in 27% yield (white powder) as described for
10a: mp168-170 °C; 1H NMR (600 MHz, CD3OD) δ 8.02 (s, 2H), 7.72 (d, J = 9.0 Hz,
2H), 7.23 – 7.19 (m, 4H), 7.15 – 7.13 (m, 1H), 7.05 (d, J = 9.0 Hz, 2H), 7.03 (d, J =
1.2 Hz, 1H), 4.35 (d, J = 15.6 Hz, 1H), 4.14 (d, J = 15.6 Hz, 1H), 4.05 – 4.01 (m, 1H),
3.84 (s, 3H), 3.82 – 3.79 (m, 1H), 3.42 (dd, J = 15.0, 3.6 Hz, 1H), 3.10 (dd, J = 14.0,
4.0 Hz, 1H), 3.00 (dd, J = 13.8, 8.4 Hz, 1H), 2.91 (dd, J = 15.0, 8.4 Hz, 1H), 2.80 (dd,
J = 13.8, 7.2 Hz, 1H), 2.64 (dd, J = 13.8, 10.8 Hz, 1H), 2.00 – 1.93 (m, 1H), 1.85 (d, J
= 1.2 Hz, 3H), 0.87 (d, J = 6.6 Hz, 3H), 0.81 (d, J = 6.6 Hz, 3H); 13C NMR (151 MHz,
CD3OD) δ 168.2, 164.6, 163.1, 157.5, 143.8, 138.5, 130.6, 129.2, 129.0, 127.9, 125.8,
114.0, 102.5, 72.1, 57.5, 54.8, 54.3, 52.5, 50.8, 34.8, 26.6, 19.1, 19.0, 11.6; HRMS
(ESI) m/z calcd. for C28H37N5O6S ([M - H]-): 570.2381, found 570.2345.
4.1.14.
2-(4-Amino-5-fluoro-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4
-methoxyphenylsulfonamido)-1-phenylbutan-2-yl)acetamide (10c)
The title compound was obtained by 2c which was coupled with 8 through

EDCI/HOBt/DMAP coupling procedure in 65% yield (white powder) as described for
10a: mp139-141 °C; 1H NMR (600 MHz, CD3OD) δ 7.72 (d, J = 9.0 Hz, 2H), 7.38 (d,
J = 6.0 Hz, 1H), 7.22 – 7.20 (m, 4H), 7.15 – 7.12 (m, 1H), 7.04 (d, J = 9.0 Hz, 2H),
4.36 (d, J = 15.6 Hz, 1H), 4.14 (d, J = 15.6 Hz, 1H), 4.06 – 4.03 (m, 1H), 3.83 (s, 3H),
3.82 – 3.80 (m, 1H), 3.40 (dd, J = 15.0, 3.6 Hz, 1H), 3.10 (dd, J = 14.0, 4.2 Hz, 1H),
2.99 (dd, J = 13.8, 8.4 Hz, 1H), 2.93 (dd, J = 15.0, 8.4 Hz, 1H), 2.81 (dd, J = 13.8, 7.2
Hz, 1H), 2.65 (dd, J = 14.0, 10.8 Hz, 1H), 1.98 – 1.94 (m, 1H), 0.86 (d, J = 6.6 Hz,
13
3H), 0.81 (d, J = 6.6 Hz, 3H); C NMR (151 MHz, CD3OD) δ 167.9, 164.7, 163.1,
155.9, 138.5, 130.6, 130.4, 129.2, 129.0, 127.9, 125.9, 114.0, 72.1, 57.5, 54.8, 54.4,
52.5, 51.0, 34.8, 26.6, 19.1, 19.0; HRMS (ESI) m/z calcd. for C27H34FN5O6S ([M -
H]-): 574.2130, found 574.2138.
4.1.15.
N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenylsulfonamido)-1-phenylbutan-2-y
l)-2-(2-oxopyrimidin-1(2H)-yl)acetamide (10d)
The title compound was obtained by 2-(2-oxopyrimidin-1(2H)-yl)acetic acid (2d)
which was coupled with 8 through EDCI/HOBt/DMAP coupling procedure in 74%
1
yield (white powder) as described for 10a: mp172-174 °C; H NMR (500 MHz,
CD3OD) δ 8.61 – 8.60 (m, 1H), 7.88 (dd, J = 6.5, 2.5 Hz, 1H), 7.80 (d, J = 8.5 Hz,
2H), 7.30 (d, J = 4.0 Hz, 4H), 7.22 (dd, J = 8.5, 4.0 Hz, 1H), 7.12 (d, J = 8.5 Hz, 2H),
6.51 (dd, J = 6.0, 4.5 Hz, 1H), 4.66 (d, J = 15.5 Hz, 1H), 4.38 (d, J = 15.5 Hz, 1H),
4.11 – 4.07 (m, 1H), 3.91 (s, 4H), 3.49 (dd, J = 15.0, 3.0 Hz, 1H), 3.21 (dd, J = 14.0,
3.5 Hz, 1H), 3.08 – 2.99 (m, 2H), 2.89 (dd, J = 13.5, 7.0 Hz, 1H), 2.73 (dd, J = 14.0,
10.5 Hz, 1H), 2.08 – 2.00 (m, 1H), 0.93 (d, J = 6.5 Hz, 3H), 0.88 (d, J = 6.5 Hz, 3H);
13C NMR (151 MHz, CD3OD) δ 168.3, 168.1, 164.6, 158.1, 152.3, 140.0, 132.2,
130.8, 130.5, 129.5, 127.4, 115.5, 106.0, 73.8, 59.1, 56.3, 56.1, 54.2, 54.1, 36.5, 28.2,
20.6, 20.5; HRMS (ESI) m/z calcd. for C27H34N4O6S ([M - H]-): 541.2115, found
541.2128.
4.1.16.

2-(4-Amino-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-nitrophe
nylsulfonamido)-1-phenylbutan-2-yl)acetamide (11a)
The title compound was obtained by 2a which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 24% yield (colorless oil) as described for
10a: mp172-174 °C; 1H NMR (400 MHz, CD3OD) δ 8.40 (d, J = 8.8 Hz, 2H), 8.08 (d,
J = 8.8 Hz, 2H), 7.28-7.22 (m, 5H), 7.19-7.16 (m, 1H), 5.80 (d, J = 7.2 Hz, 1H), 4.42
(d, J = 15.6 Hz, 1H), 4.12 (d, J = 15.6 Hz, 1H), 4.00 (ddd, J = 10.4, 6.4, 4.0 Hz, 1H),
3.83 – 3.79 (m, 1H), 3.51 (dd, J = 15.0, 2.8 Hz, 1H), 3.20- 3.10 (m, 3H), 3.02-2.96 (m,
1H), 2.68 (dd, J = 13.8, 10.4 Hz, 1H), 2.07-1.99 (m, 1H), 0.91 (d, J = 6.6 Hz, 3H),
0.86 (d, J = 6.6 Hz, 3H); 13C NMR (101 MHz, CD3OD) δ 169.6, 168.0, 158.6, 151.4,
148.1, 146.9, 139.8, 130.4, 129.9, 129.4, 127.3, 125.4, 95.7, 73.0, 58.0, 55.9, 53.2,
52.6, 36.4, 27.8, 20.4; HRMS (ESI) m/z calcd. for C26H32N6O7S ([M - H]-): 571.1969,
found 571.1946.
4.1.17.
2-(4-Amino-5-methyl-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobuty-4
-nitrophenylsulfonamido)-1-phenylbutan-2-yl)acetamide (11b)
The title compound was obtained by 2b which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 58% yield (colorless oil) as described for
10a: mp212-214 °C; 1H NMR (400 MHz, CD3OD) δ 8.36 (d, J = 8.8 Hz, 2H), 8.04 (d,
J = 8.8 Hz, 2H), 7.24-7.17 (m, 4H), 7.15-7.12 (m, 1H), 7.07 (s, 1H), 4.36 (d, J = 15.8
Hz, 1H), 4.09 (d, J = 15.8 Hz, 1H), 3.99-3.94 (m, 1H), 3.79-3.74 (m, 1H), 3.47 (dd, J
= 15.0, 2.9 Hz, 1H), 3.16-3.05 (m, 3H), 2.98-2.93 (m, 1H), 2.63 (dd, J = 13.8, 10.4 Hz,
1H), 1.99 (dt, J = 14.0, 6.8 Hz, 1H), 1.86 (s, 3H), 0.88 (d, J = 6.6 Hz, 3H), 0.82 (d, J =
6.6 Hz, 3H); 13C NMR (101 MHz, CD3OD) δ 169.7, 167.7, 158.8, 151.4, 146.9, 145.4,
139.8, 130.4, 129.9, 129.4, 127.3, 125.4, 103.9, 73.0, 58.0, 55.9, 53.2, 52.5, 36.4, 27.8,
20.4, 13.1; HRMS (ESI) m/z calcd. for C27H34N6O7S ([M - H]-): 585.2126, found
585.2116.
4.1.18.

2-(4-Amino-5-fluoro-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4
-nitrophenylsulfonamido)-1-phenylbutan-2-yl)acetamide (11c)
The title compound was obtained by 2c which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 60% yield (white powder) as described for
10a: mp230-232 °C; 1H NMR (400 MHz, CD3OD) δ 8.36 (d, J = 8.8 Hz, 2H), 8.04 (d,
J = 8.8 Hz, 2H), 7.43 (d, J = 6.0 Hz, 1H), 7.24-7.18 (m, 4H), 7.16-7.12 (m, 1H), 4.36
(d, J = 15.8 Hz, 1H), 4.09 (d, J = 15.8 Hz, 1H), 3.97 (ddd, J = 10.4, 6.4, 4.0 Hz, 1H),
3.80 – 3.75 (m, 1H), 3.47 (dd, J = 15.0, 2.8 Hz, 1H), 3.16-3.06 (m, 3H), 2.95 (dd, J =
13.6, 7.2 Hz, 1H), 2.64 (dd, J = 13.6, 10.4 Hz, 1H), 2.04-1.94 (m, 1H), 0.88 (d, J =
13
6.6 Hz, 3H), 0.82 (d, J = 6.6 Hz, 3H); C NMR (101 MHz, CD3OD) δ 169.4, 160.0,
157.2, 151.4, 146.8, 139.8, 132.2, 131.9, 130.4, 129.9, 129.4, 127.3, 125.4, 73.0, 58.0,
55.9, 53.2, 52.6, 36.4, 27.8, 20.4; HRMS (ESI) m/z calcd. for C26H31FN6O7S ([M -
H]-): 589.1875, found 589.1886.
4.1.19.
N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-nitrophenylsulfonamido)-1-phenylbutan-2-yl)-
2-(2-oxopyrimidin-1(2H)-yl)acetamide (11d)
The title compound was obtained by 2d which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 46% yield (white powder) as described for
10a: mp168-170 °C; 1H NMR (600 MHz, DMSO-d6) δ 8.56 (dd, J = 4.2, 2.8 Hz, 1H),
8.40 (d, J = 9.0 Hz, 2H), 8.13 (d, J = 9.0 Hz, 2H), 7.96 (dd, J = 6.6, 3.0 Hz, 1H),
7.27-7.21 (m, 4H), 7.17 (dt, J = 8.4, 1.2 Hz, 1H), 6.41 (dd, J = 6.6, 4.2 Hz, 1H), 4.53
(d, J = 15.0 Hz, 1H), 4.23 (d, J = 15.0 Hz, 1H), 3.75 (td, J = 10.8, 3.6 Hz, 1H), 3.62
(ddd, J = 17.0, 7.2, 3.0 Hz, 1H), 3.44 (dd, J = 14.8, 2.4 Hz, 1H), 3.10-3.05 (m, 2H),
2.95 (dd, J = 15.0, 9.6 Hz, 1H), 2.87 (dd, J = 13.8, 6.0 Hz, 1H), 2.55 (dd, J = 13.8,
10.8 Hz, 1H), 2.00-1.95 (m, 1H), 0.83 (d, J = 6.6 Hz, 3H), 0.76 (d, J = 6.6 Hz, 3H);
13C NMR (151 MHz, DMSO-d6) δ 166.5, 166.1, 155.6, 150.9, 149.5, 145.1, 139.1,
129.1, 128.7, 1281, 125.9, 124.5, 103.4, 71.5, 56.2, 54.3, 52.5, 52.0, 35.4, 25.8, 19.9,
19.8; HRMS (ESI) m/z calcd. for C26H31N5O7S ([M - H]-): 556.1860, found 556.1858.

4.1.20.
2-(4-Amino-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-4-(4-amino-N-
isobutylphenylsulfonamido)-3-hydroxy-1-phenylbutan-2-yl)acetamide (12a)
To a flask was added 11a (0.050 g, 0.087 mmol) 10% d/C (humidity 37%) (0.050 g,
w/w 0.37:1), ammonium formate (0.034 g, 0.52 mmol) and methanol (2 mL). The
reaction mixture was refluxed for 1 hour, and then filtered using a pad of Celite 545®
followed by washing with a little methanol. The solvent was removed under reduced
pressure. The residue was purified by silica gel preparation thin layer chromatography
with the developing solvent ethyl acetate/methanol 6: 1. 12a was obtained as yellow
powder: yield 0.038 g (81%); mp206-208 °C; 1H NMR (600 MHz, CD3OD) δ 7.49 (d,
J = 8.8 Hz, 2H), 7.26-7.25 (m, 4H), 7.20 (d, J = 7.2 Hz, 1H), 7.18 (dd, J = 8.8, 4.8 Hz,
1H), 6.71 (d, J = 8.8 Hz, 2H), 5.79 (d, J = 7.2 Hz, 1H), 4.40 (d, J = 15.8 Hz, 1H), 4.19
(d, J = 15.8 Hz, 1H), 4.10 -4.07 (m, 1H), 3.87-3.84 (m, 1H), 3.40 (dd, J = 15.0, 3.6 Hz,
1H), 3.14 (dd, J = 13.8, 3.6 Hz, 1H),3.00-2.90 (m, 2H), 2.80 (dd, J = 13.8, 7.2 Hz,
1H), 2.69 (dd, J = 13.8, 10.8 Hz, 1H), 1.99 (dt, J = 13.8, 6.6 Hz, 1H), 0.91 (d, J = 6.6
Hz, 3H), 0.86 (d, J = 6.6 Hz, 3H); 13C NMR (151 MHz, CD3OD) δ 169.0, 167.6,
158.4, 153.8, 147.3, 139.5, 130.0, 128.8, 126.7, 125.5, 114.0, 95.3, 73.1, 58.7, 55.3,
53.7, 51.9, 35.7, 27.7, 20.1, 20.0; HRMS (ESI) m/z calcd. for C26H34N6O5S ([M - H]-):
541.2228, found 541.2210.
4.1.21.
2-(4-Amino-5-methyl-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-4-(4-amino-N-
isobutylphenylsulfonamido)-3-hydroxy-1-phenylbutan-2-yl)acetamide (12b)
The title compound was obtained by hydrogenation of 11b in 75% yield (yellow
powder) as described for 12a: mp145-147 °C; 1H NMR (400 MHz, CD3OD) δ 7.45 (d,
J = 8.8 Hz, 2H), 7.22- 7.20 (m, 4H), 7.16-7.11 (m, 1H), 7.02 (s, 1H), 6.67 (d, J = 8.8
Hz, 2H), 4.34 (d, J = 15.8 Hz, 1H), 4.17 (d, J = 15.8 Hz, 1H), 4.08-4.03 (m, 1H),
3.83-3.79 (m, 1H), 3.37 (dd, J = 14.8, 3.6 Hz, 1H), 3.10 (dd, J = 13.6, 4.0 Hz, 1H),
2.97-2.84 (m, 2H), 2.75 (dd, J = 13.6, 7.0 Hz, 1H), 2.64 (dd, J = 13.6, 10.4 Hz, 1H),
1.98-1.89 (m, 1H), 1.85 (s, 3H), 0.87 (d, J = 6.6 Hz, 3H), 0.82 (d, J = 6.6 Hz, 3H); 13C
NMR (101 MHz, CD3OD) δ 169.6, 167.7, 158.9, 154.3, 145.2, 140.0, 130.5, 129.3,
127.2, 125.9, 114.5, 104.0, 73.6, 59.2, 55.7, 54.2, 52.2, 36.2, 28.2, 20.6, 20.5, 13.1;

HRMS (ESI) m/z calcd. for C27H36N6O5S ([M - H]-): 555.2384, found 555.2362.
4.1.22.
2-(4-Amino-5-fluoro-2-oxopyrimidin-1(2H)-yl)-N-((2S,3R)-4-(4-amino-N-
isobutylphenylsulfonamido)-3-hydroxy-1-phenylbutan-2-yl)acetamide (12c)
The title compound was obtained by hydrogenation of 11c in 48% yield (yellow
powder) as described for 12a: mp179-181 °C; 1H NMR (500 MHz, CD3OD) δ 7.52 (d,
J = 8.5 Hz, 2H), 7.43 (d, J = 6.0 Hz, 1H), 7.31 – 7.28 (m, 4H), 7.22 – 7.17 (m, 1H),
6.74 (d, J = 8.5 Hz, 2H), 4.40 (d, J = 16.0 Hz, 1H), 4.23 (d, J = 16.0 Hz, 1H), 4.14 –
4.10 (m, 1H), 3.88 (t, J = 8.5 Hz, 1H), 3.43 (dd, J = 15.0, 3.5 Hz, 1H), 3.17 (dd, J =
14.0, 3.5 Hz, 1H), 3.01 (dd, J = 13.5, 8.0 Hz, 1H), 2.94 (dd, J = 15.0, 8.0 Hz, 1H),
2.83 (dd, J = 13.5, 7.0 Hz, 1H), 2.71 (dd, J = 13.5, 10.5 Hz, 1H), 2.06 – 1.98 (m, 1H),
13
0.94 (d, J = 6.5 Hz, 3H), 0.89 (d, J = 6.5 Hz, 3H); C NMR (101 MHz, CD3OD) δ
169.4, 160.1, 160.0, 157.4, 154.4, 140.1, 136.9, 132.1, 131.8, 130.6, 129.4, 127.3,
126.0, 114.6, 73.7 59.3, 55.9, 54.3, 52.4, 36.3, 28.3, 20.7, 20.6; HRMS (ESI) m/z
calcd. for C26H33FN6O5S ([M - H]-): 559.1875, found 559.2108.
4.1.23.
N-((2S,3R)-4-(4-amino-N-isobutylphenylsulfonamido)-3-hydroxy-1-phenylbutan-2-yl)
-2-(2-oxopyrimidin-1(2H)-yl)acetamide (12d)
The title compound was obtained by hydrogenation of 11d in 85% yield (yellow
1
powder) as described for 12a: mp171-173 °C; H NMR (600 MHz, CD3OD) δ 8.54
(dd, J = 4.2, 3.0 Hz, 1H), 7.80 (dd, J = 6.6, 3.0 Hz, 1H), 7.46 (d, J = 9.0 Hz, 2H), 7.24
– 7.21 (m, 4H), 7.15 – 7.13 (m, 1H), 6.67 (d, J = 9.0 Hz, 2H), 6.44 (dd, J = 6.6, 4.2
Hz, 1H), 4.57 (d, J = 15.6 Hz, 1H), 4.34 (d, J = 15.6 Hz, 1H), 4.06 – 4.02 (m, 1H),
3.83 – 3.80 (m, 1H), 3.37 (dd, J = 15.0, 3.6 Hz, 1H), 3.13 (dd, J = 13.8, 4.0 Hz, 1H),
2.93 (dd, J = 13.2, 7.2 Hz, 1H), 2.89 (dd, J = 14.4, 7.8 Hz, 1H), 2.77 (dd, J = 13.8, 7.2
Hz, 1H), 2.66 (dd, J = 13.8, 10.2 Hz, 1H), 1.97 – 1.93 (m, 1H), 0.87 (d, J = 6.6 Hz,
13
3H), 0.83 (d, J = 6.6 Hz, 3H); C NMR (151 MHz, CD3OD) δ 166.7, 166.5, 156.6,
152.8, 150.8, 138.5, 129.4, 129.0, 127.9, 125.8, 113.1, 104.4, 72.3, 57.9, 54.5, 52.8,
52.5, 34.9, 26.7, 19.2, 19.1; HRMS (ESI) m/z calcd. for C26H33N5O5S ([M - H]-):

526.2119, found 526.2151.
4.1.24.
2-(2,4-Dioxo-3,4-dihydropyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-
methoxyphenylsulfonamido)-1-phenylbutan-2-yl)acetamide (10e)
The title compound was obtained by 2e which was coupled with 8 through
EDCI/HOBt/DMAP coupling procedure in 98% yield (white powder) as described for
10a: mp125-127 °C; 1H NMR (500 MHz, CD3OD) δ 7.80 (d, J = 8.5 Hz, 2H), 7.31 –
7.27 (m, 4H), 7.22 – 7.21 (m, 2H), 7.12 (d, J = 8.5 Hz, 2H), 5.62 (d, J = 8.0 Hz, 1H),
4.42 (d, J = 16.0 Hz, 1H), 4.19 (d, J = 16.0 Hz, 1H), 4.10 – 4.06 (m, 1H), 3.90 (s, 3H),
3.89 – 3.85 (m, 1H), 3.47 (dd, J = 15.0, 3.0 Hz, 1H), 3.21 (dd, J = 14.0, 3.5 Hz, 1H),
3.06 (dd, J = 13.5, 8.0 Hz, 1H), 2.98 (dd, J = 15.0, 8.5 Hz, 1H), 2.88 (dd, J = 13.5, 7.0
Hz, 1H), 2.70 (dd, J = 13.5, 1.0 Hz, 1H), 2.08 – 2.00 (m, 1H), 0.94 (d, J = 6.5 Hz, 3H),
0.89 (d, J = 6.5 Hz, 3H); 13C NMR (151 MHz, CD3OD) δ 169.1, 166.9, 164.7, 152.8,
147.6, 140.0, 132.2, 130.8, 130.5, 129.5, 127.4, 115.6, 102.3, 74.0, 59.2, 56.3, 56.0,
54.3, 51.0, 36.7, 28.2, 20.7, 20.6; HRMS (ESI) m/z calcd. for C27H34N4O7S ([M - H]-):
557.2064, found 557.2060.
4.1.25.
N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenylsulfonamido)-1-phenylbutan-2-y
l)-2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (10f)
The title compound was obtained by 2f which was coupled with 8 through
EDCI/HOBt/DMAP coupling procedure in 83% yield (white powder) as described for
10a: mp188-190 °C; 1H NMR (600 MHz, CD3OD) δ 7.72 (d, J = 9.0 Hz, 2H), 7.24 –
7.19 (m, 4H), 7.16 – 7.13 (m, 1H), 7.04 (d, J = 9.0 Hz, 2H), 6.97 (d, J = 1.2 Hz, 1H),
4.32 (d, J = 16.2 Hz, 1H), 4.11 (d, J = 16.2 Hz, 1H), 4.03 – 4.00 (m, 1H), 3.83 (s, 3H),
3.82 – 3.79 (m, 1H), 3.41 (dd, J = 15.0, 3.6 Hz, 1H), 3.14 (dd, J = 14.0, 4.2 Hz, 1H),
3.00 (dd, J = 13.8, 8.4 Hz, 1H), 2.90 (dd, J = 15.0, 8.4 Hz, 1H), 2.80 (dd, J = 13.8, 7.2
Hz, 1H), 2.63 (dd, J = 13.8, 10.8 Hz, 1H), 2.00 – 1.95 (m, 1H), 1.77 (d, J = 1.2 Hz,
3H), 0.87 (d, J = 6.6 Hz, 3H), 0.81 (d, J = 6.6 Hz, 3H); 13C NMR (151 MHz, CD3OD)

δ 167.7, 165.5, 163.1, 151.4, 141.8, 138.5, 130.6, 129.2, 129.0, 127.9, 125.9, 114.0,
109.6, 72.5, 57.6, 54.8, 54.4, 52.7, 49.2, 35.1, 26.6, 19.1, 19.0, 10.8; HRMS (ESI) m/z
calcd. for C28H36N4O7S ([M - H]-): 571.2221, found 571.2188.
4.1.26.
2-(5-Fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-
isobutyl-4-methoxyphenylsulfonamido)-1-phenylbutan-2-yl)acetamide (10g)
The title compound was obtained by 2g which was coupled with 8 through
EDCI/HOBt/DMAP coupling procedure in 99% yield (white powder) as described for
10a: mp138-140 °C; 1H NMR (500 MHz, CD3OD) δ 7.80 (d, J = 8.5 Hz, 2H), 7.44 (d,
J = 6.0 Hz, 1H), 7.32 – 7.27 (m, 4H), 7.22 (t, J = 7.0 Hz, 1H), 7.12 (d, J = 8.5 Hz, 2H),
4.38 (d, J = 16.0 Hz, 1H), 4.19 (d, J = 16.0 Hz, 1H), 4.11 – 4.07 (m, 1H), 3.91 (s, 3H),
3.89 – 3.86 (m, 1H), 3.47 (dd, J = 15.0, 3.0 Hz, 1H), 3.21 (dd, J = 14.0, 3.5 Hz, 1H),
3.07 (dd, J = 13.5, 8.0 Hz, 1H), 2.98 (dd, J = 15.0, 8.5 Hz, 1H), 2.88 (dd, J = 13.5, 7.0
Hz, 1H), 2.70 (dd, J = 13.5, 11.0 Hz, 1H), 2.07 – 2.00 (m, 1H), 0.94 (d, J = 6.5 Hz,
13
3H), 0.89 (d, J = 6.5 Hz, 3H); C NMR (151 MHz, CD3OD) δ 168.9, 164.6, 160.0,
159.9, 151.5, 142.3, 140.7, 140.0, 132.1, 131.5, 131.3, 130.7, 130.5, 129.4, 127.4,
115.5, 74.0, 59.1, 56.3, 55.9, 54.2, 51.0, 36.6, 28.1, 20.6, 20.5; HRMS (ESI) m/z calcd.
for C27H33FN4O7S ([M - H]-): 575.1970, found 575.1996.
4.1.27.
N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenylsulfonamido)-1-phenylbutan-2-y
l)-2-(5-hydroxymethyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (10h)
The title compound was obtained by 2h which was coupled with 8 through
EDCI/HOBt/DMAP coupling procedure in 99% yield (white powder) as described for
1
10a: mp171-173 °C; H NMR (600 MHz, CD3OD) δ 7.66 (d, J = 9.0 Hz, 2H),
7.18-7.12 (m, 5H), 7.09-7.06 (m, 1H), 6.98 (d, J = 9.0 Hz, 2H), 4.30 (d, J = 16.2 Hz,
1H), 4.17 (t, J = 1.2 Hz, 2H), 4.08 (d, J = 16.2 Hz, 1H), 3.96-3.92 (m, 1H), 3.77 (s,
3H), 3.75-3.71 (m, 1H), 3.33 (dd, J = 15.0, 3.6 Hz, 1H), 3.07 (dd, J = 14.0, 3.6 Hz,
1H), 2.92 (dd, J = 13.6, 8.4 Hz, 1H), 2.83 (dd, J = 15.0, 8.4 Hz, 1H), 2.73 (dd, J =

13.8, 7.0 Hz, 1H), 2.56 (dd, J = 13.8, 10.8 Hz, 1H), 1.90-1.85 (m, 1H), 0.80 (d, J =
13
6.6 Hz, 3H), 0.74 (d, J = 6.6 Hz, 3H); C NMR (151 MHz, CD3OD) δ 169.1, 165.6,
164.6, 152.7, 144.4, 139.9, 132.0, 130.7, 130.4, 129.4, 127.3, 115.4, 114.8, 73.94 (s),
59.1, 57.7, 56.2, 55.9, 54.2, 50.9, 36.6, 28.0, 20.5, 20.4; HRMS (ESI) m/z calcd. for
C28H36N4O8S ([M - H]-): 587.2170, found 587.2192.
4.1.28.
2-(2,4-Dioxo-3,4-dihydropyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-
isobutyl-4-nitrophenylsulfonamido)-1-phenylbutan-2-yl)acetamide (11e)
The title compound was obtained by 2e which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 85% yield (colorless acicular crystal) as
1
described for 10a: mp157-159 °C; H NMR (600 MHz, DMSO-d6) δ 11.32 (s, 1H),
8.41 (d, J = 9.0 Hz, 2H), 8.18 (d, J = 9.0 Hz, 1H), 8.09 (d, J = 9.0 Hz, 2H), 7.32 (d, J
= 7.8 Hz, 1H), 7.26 (t, J = 7.2 Hz, 2H), 7.21-7.16 (m, 3H), 5.53 (dd, J = 7.8, 2.4 Hz,
1H), 4.28 (d, J = 16.2 Hz, 1H), 4.14 (d, J = 16.2 Hz, 1H), 3.82-3.77 (m, 1H), 3.61 (m,
1H), 3.41 (dd, J = 15.0, 2.8 Hz, 1H), 3.13 (dd, J = 13.8, 8.4 Hz, 1H), 3.03-2.98 (m,
2H), 2.91 (d, J = 6.6 Hz, 1H), 2.56 (dd, J = 14.0, 10.2 Hz, 1H), 2.00-1.92 (m, 1H),
0.84 (d, J = 6.6 Hz, 3H), 0.78 (d, J = 6.6 Hz, 3H); 13C NMR (151 MHz, DMSO-d6) δ
166.5, 163.9, 149.6, 146.4, 145.3, 139.0, 129.2, 128.6, 125.9, 124.5, 100.5, 71.2, 55.8,
54.0, 51.5, 49.5, 35.2, 25.8, 19.9, 19.7; HRMS (ESI) m/z calcd. for C26H31N5O8S ([M
- H]-): 572.1810, found 572.1776.
4.1.29.
N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-nitrophenylsulfonamido)-1-phenylbutan-2-yl)-
2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (11f)
The title compound was obtained by 2f which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 86% yield (white powder) as described for
10a: mp172-174 °C; 1H NMR (400 MHz, DMSO-d6) δ 11.31 (s, 1H), 8.40 (d, J = 8.8
Hz, 2H), 8.15 (d, J = 9.0 Hz, 1H), 8.08 (d, J = 8.8 Hz, 2H), 7.27-7.24 (m, 2H),
7.21-7.17 (m, 3H), 7.16 (s, 1H), 5.11 (d, J = 7.0 Hz, 1H), 4.25 (d, J = 16.4 Hz, 1H),
4.07 (d, J = 16.4 Hz, 1H), 3.78 (td, J = 10.4, 3.2 Hz, 1H), 3.60 (td, J = 9.6, 2.8 Hz,

1H), 3.42-3.39 (m, 1H), 3.13 (dd, J = 13.6, 8.8 Hz, 1H), 3.04-2.95 (m, 2H), 2.91 (d, J
= 6.4 Hz, 1H), 2.58-2.55 (m, 1H), 2.00-1.93 (m, 1H), 1.73 (s, 3H), 0.84 (d, J = 6.6 Hz,
3H), 0.77 (d, J = 6.6 Hz, 3H); 13C NMR (101 MHz, DMSO-d6) δ 166.6, 164.4, 150.9,
149.5, 145.2, 142.0, 139.0, 129.1, 128.6, 128.0, 125.9, 124.5, 108.0, 71.3, 55.8, 54.0,
51.5, 49.3, 35.2, 25.8, 19.9, 19.7, 11.9; HRMS (ESI) m/z calcd. for C27H33N5O8S ([M
- H]-): 586.1966, found 586.1991.
4.1.30.
2-(5-Fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-N-((2S,3R)-3-hydroxy-4-(N-
isobutyl-4-nitrophenylsulfonamido)-1-phenylbutan-2-yl)acetamide (11g)
The title compound was obtained by 2g which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 76% yield (white powder) as described for
10a: mp146-148 °C; 1H NMR (500 MHz, CD3OD) δ 8.44 (d, J = 8.5 Hz, 2H), 8.12 (d,
J = 8.5 Hz, 2H), 7.49 (d, J = 6.0 Hz, 1H), 7.32 – 7.27 (m, 2H), 7.26 (d, J = 7.0 Hz,
2H), 7.22 (t, J = 7.0 Hz, 1H), 4.39 (d, J = 16.5 Hz, 1H), 4.16 (d, J = 16.5 Hz, 1H),
4.06 – 4.02 (m, 1H), 3.86 – 3.83 (m, 1H), 3.55 (dd, J = 15.0, 2.0 Hz, 1H), 3.24 – 3.12
(m, 3H), 3.02 (dd, J = 13.5, 6.5 Hz, 1H), 2.69 (dd, J = 14.0, 11.0 Hz, 1H), 2.11 – 2.03
13
(m, 1H), 0.95 (d, J = 6.5 Hz, 3H), 0.88 (d, J = 6.5 Hz, 3H); C NMR (101 MHz,
CD3OD) δ 168.9, 160.1, 159.8, 151.4, 146.8, 142.6, 140.3, 139.8, 131.7, 131.3, 130.4,
129.9, 129.4, 127.4, 125.4, 73.3, 58.1, 55.9, 53.3, 51.1, 36.7, 27.7, 20.4; HRMS (ESI)
m/z calcd. for C26H30FN5O8S ([M - H]-): 590.1715, found 590.1746.
4.1.31.
N-((2S,3R)-3-hydroxy-4-(N-isobutyl-4-nitrophenylsulfonamido)-1-phenylbutan-2-yl)-
2-(5-hydroxymethyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (11h)
The title compound was obtained by 2h which was coupled with 9 through
EDCI/HOBt/DMAP coupling procedure in 54% yield (colorless oil) as described for
10a: mp194-196 °C; 1H NMR (600 MHz, CD3OD) δ 8.29 (d, J = 9.0 Hz, 2H), 7.97 (d,
J = 9.0 Hz, 2H), 7.15 (dd, J = 13.2, 6.0 Hz, 3H), 7.13-7.11 (m, 2H), 7.09-7.06 (m, 1H),
4.29 (d, J = 16.2 Hz, 1H), 4.18 (dd, J = 3.0, 1.2 Hz, 2H), 4.06 (d, J = 16.2 Hz, 1H),

3.89 (ddd, J = 10.8, 7.2, 4.2 Hz, 1H), 3.70 (ddd, J = 9.6, 7.2, 2.8 Hz, 1H), 3.41 (dd, J
= 15.0, 2.8 Hz, 1H), 3.09-2.98 (m, 3H), 2.89-2.85 (m, 1H), 2.55 (dd, J = 14.0, 10.8 Hz,
1H), 1.95-1.90 (m, 1H), 0.80 (d, J = 6.6 Hz, 3H), 0.74 (d, J = 6.6 Hz, 3H); 13C NMR
(151 MHz, CD3OD) δ 169.1, 165.6, 152.7, 151.4, 146.8, 144.34, 139.8, 130.3, 129.9,
129.4, 127.4, 125.4, 114.8, 73.4, 58.1, 57.7, 55.9, 53.3, 51.1, 36.7, 27.7, 20.3; HRMS
(ESI) m/z calcd. for C27H33N5O9S ([M - H]-): 602.1915, found 602.1893.
4.1.32.
N-((2S,3R)-4-(4-amino-N-isobutylphenylsulfonamido)-3-hydroxy-1-phenylbutan-2-yl)
-2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (12e)
The title compound was obtained by hydrogenation of 11e in 95% yield (colorless
oil) as described for 12a: mp156-158 °C; 1H NMR (500 MHz, CD3OD) δ 7.53 (d, J =
8.5 Hz, 2H), 7.31 – 7.28 (m, 4H), 7.22 (d, J = 8.0 Hz, 2H), 6.74 (d, J = 8.5 Hz, 2H),
5.62 (d, J = 8.0 Hz, 1H), 4.39 (d, J = 16.0 Hz, 1H), 4.22 (d, J = 16.0 Hz, 1H), 4.12 –
4.08 (m, 1H), 3.89 – 3.85 (m, 1H), 3.43 (d, J = 3.0 Hz, 1H), 3.21 (dd, J = 14.0, 3.5 Hz,
1H), 3.00 (dd, J = 13.5, 8.0 Hz, 1H), 2.95 (dd, J = 15.0, 8.5 Hz, 1H), 2.84 (dd, J =
13.5, 7.0 Hz, 1H), 2.70 (dd, J = 13.5, 11.0 Hz, 1H), 2.06 – 1.98 (m, 1H), 0.94 (d, J =
13
6.5 Hz, 3H), 0.90 (d, J = 6.5 Hz, 3H); C NMR (151 MHz, CD3OD) δ 169.0, 166.8,
154.3, 152.7, 147.6, 140.0, 130.6, 130.5, 129.4, 127.4, 126.1, 114.6, 102.3, 74.0, 59.4,
55.9, 54.4, 50.9, 36.6, 28.2, 20.7, 20.6; HRMS (ESI) m/z calcd. for C26H33N5O6S ([M
- H]-): 542.2068, found 542.2103.
4.1.33.
N-((2S,3R)-4-(4-amino-N-isobutylphenylsulfonamido)-3-hydroxy-1-phenylbutan-2-yl)
-2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (12f)
The title compound was obtained by hydrogenation of 11f in 77% yield (faint
yellow powder) as described for 12a: mp186-188 °C; 1H NMR (600 MHz, CD3OD) δ
7.45 (d, J = 9.0 Hz, 2H), 7.24 – 7.19 (m, 4H), 7.16 – 7.13 (m, 1H), 6.98 (d, J = 1.2 Hz,
1H), 6.67 (d, J = 9.0 Hz, 2H), 4.29 (d, J = 16.2 Hz, 1H), 4.14 (d, J = 16.2 Hz, 1H),
4.05 – 4.01 (m, 1H), 3.81 – 3.78 m, 1H), 3.37 (dd, J = 15.0, 3.6 Hz, 1H), 3.14 (dd, J =