Multifunctional Inhibitors of HIV-1-RT
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 25 5193
512 matrix with a spectral width of 3461 Hz and 1.2 s of
relaxation delay and then processed in a 2048 × 1024 matrix.
In the TOCSY spectra a mixing time of 0.128 s was used. 2D
inverse proton detected heteronuclear one-bond shift correla-
tion spectra were obtained using the pulsed field gradient
HSQC pulse sequence. Data were collected in a 2048 × 512
matrix with a spectral width of 3460 Hz in the proton domain
and 22500 Hz in the carbon domain and were processed in a
2048 × 1024 matrix. The experiment was optimized for a one-
bond heteronuclear coupling constant of 150 Hz. 2D inverse
proton detected heteronuclear long-range shift correlation
spectra were obtained using the pulsed field gradient HMBC
pulse sequence. The HMBC experiment was acquired in the
same conditions of the HSQC experiment and optimized for
long-range coupling constants of 7 Hz. 1D-selective TOCSY
experiments were acquired using a selective pulse EBURP2-
256 with a B1 corresponding to 10 Hz and a spin-lock time of
128 ms.
Gen er a l P r oced u r e for th e Syn th esis of 3-N-(br om o-
sp a cer ) Nu cleosid e In ter m ed ia tes 3a , 4a , a n d 9a -d a n d
3-N -(B r o m o a lk y l)-5′-(p h e n y lm e t h o x y a la n in y l)p h o s -
p h a t e Nu cleot id e In t er m ed ia t es 3b-d a n d 4b-d . To a
solution of the nucleoside [AZT or d4T] (1 equiv) in acetone/
DMF (1:1) or the nucleotide (2d ) (1 equiv) in acetone were
added K2CO3 (1.1 equiv) and the corresponding dibromoalkyl,
alkenyl, aryl, or dichloroalkynyl reagent (2.0-6.0 equiv). The
reaction mixture was refluxed for 5-16 h. After evaporation
of the solvent, the residue was dissolved in ethyl acetate (14
mL), washed with water (2 × 14 mL), dried (Na2SO4), filtered,
and evaporated to dryness. The residue was purified by
CCTLC on the chromatotron. The reaction time, number of
equivalents of the dibromo reagent, chromatography eluent,
1
yield of the isolated products, and H NMR data are indicated
below for each compound.
N-(3-Br om op r op yl)-2′,3′-d id eh yd r o-2′,3′-d id eoxyth ym i-
d in e (3a ): reaction time 16 h; 6 equiv of 1,3-dibromopropane;
eluent dichloromethane/methanol, 20:1; yield of 3a (75%) as
Analytical TLC was performed on silica gel 60 F254 (Merck).
Separations on silica gel were performed by preparative
centrifugal circular thin-layer chromatography (CCTLC) on a
1
a syrup; H NMR (CDCl3) δ 1.80 (d, 3H, CH3-5, J ) 1.2 Hz),
2.17 (m, 2H, CH2), 3.51 (t, 2H, CH2Br, J ) 7.0 Hz), 3.79 (m,
2H, 2H-5′), 4.03 (t, 2H, CH2N, J ) 7.0 Hz), 4.12 (t, 1H, OH-
5′), 4.46 (m, 1H, H-3′), 4.86 (m, 1H, H-4′), 5.92 (ddd, 1H, H-2′,
J 2′,3′ ) 6.0, J 1′,2′ ) 1.3, J 2′,4′ ) 2.3 Hz), 6.42 (dt, 1H, H-3′, J 1′,3′
) J 3′,4′ ) 1.7 Hz), 6.99 (m, 1H, H-1′), 7.78 (q, 1H, H-6). Anal.
(C13H17BrN2O4) C, H, N.
Chromatotron (Kiesegel 60 PF
gipshaltig (Merck)), layer
254
thickness (1 mm), flow rate (5 mL/min). Flash column chro-
matography was performed with silica gel 60 (230-400 mesh)
(Merck). Analytical HPLC was carried out on a Waters 484
system using a mBondapak C18 (3.9 × 300 mm: 10 mm). The
systems used were as follows: (A) isocratic conditions, mobile
phase CH3CN/H2O (0.05% TFA); (B) gradient conditions,
mobile phase CH3CN/H2O (0.05% TFA); (C) linear gradient
conditions, 2-22 min 95%-10% water, 22-32 min 10% water,
32-50 min 10%-95% water. Flow rate: 1 mL/min. Detec-
tion: UV (214 nm). All retention times are quoted in minutes.
The phosphoramidate intermediates and heterodimers (2d ,
3b-d , 4b-d , 5b-d , and 6b-d ) were isolated as mixtures of
diastereoisomers, with the isomerism arising from mixed
stereochemistry at the phosphate center. Many NMR peaks
of the phosphoramidate compounds are split due to the
presence of diastereoisomers in the sample. These compounds
were noted to be hygroscopic and did not give useful microana-
lytical data but were found to be pure by high-field multi-
nuclear NMR spectroscopy, mass spectrometry, and rigorous
HPLC analysis.
3′-Azid o-3-N-(3-b r om op r op yl)-3′-d eoxyt h ym id in e-5′-
(p h en ylm eth oxya la n in yl)p h osp h a te (3b): reaction time 9
h; 4 equiv of 1,3-dibromopropane; eluent dichloromethane/
methanol, 20:1; yield of 3b (74%) as a syrup; HPLC Rt ) 5.70
1
min (system A, 45:55); 31P NMR (CDCl3) 3.14, 3.49 ppm; H
NMR (CDCl3) δ 1.34, 1.37 (d, 3H, Ala-CH3, J ) 7.0 Hz), 1.88,
1.90 (s, 3H, CH3-5), 2.05-2.48 (m, 4H, 2H-2′, CH2), 3.39 (t,
2H, CH2Br, J ) 6.8 Hz), 3.60 (m, 1H, Ala-NH), 3.68, 3.69 (s,
3H, Ala-OCH3), 3.92-4.40 (m, 7H, CH2N, Ala-CH, H-3′, H-4′,
2H-5′), 6.21 (m, 1H, H-1′), 7.16-7.38 (m, 6H, H-6, Ph); MS
m/e FAB 628.1040 (MH+, C23H30BrN6O8P requires 628.1045).
3-N-(3-Br om op r op yl)-2′,3′-d id eh yd r o-2′,3′-d id eoxyth y-
m id in e-5′-(p h en ylm eth oxya la n in yl)p h osp h a te (3c): reac-
tion time 7 h; 2 equiv of 1,3-dibromopropane; eluent dichlo-
romethane/methanol, 10:1; yield of 3c (48%) as a syrup; HPLC
Rt ) 5.51 min (system A, 40:60); 31P NMR (CDCl3) 3.13, 3.69
1
ppm; H NMR (CDCl3) δ 1.24, 1.28 (d, 3H, Ala-CH3, J ) 7.0,
All experiments involving water-sensitive compounds were
conducted under scrupulously dry conditions. Triethylamine
and acetonitrile were dried by refluxing over calcium hydride.
Tetrahydrofuran was dried by refluxing over sodium/ben-
zophenone. Anhydrous N,N′-dimethylformamide was pur-
chased from Aldrich.
7.0 Hz), 1.77, 1.81 (d, 3H, CH3-5, J ) 1.2, 1.2 Hz), 2.16 (m,
2H, CH2), 3.36, 3.36 (t, 2H, CH2Br, J ) 7.1, 7.1 Hz), 3.42, 3.50
(m, 1H, Ala-NH), 3.63, 3.64 (s, 3H, Ala-OCH3), 3.91 (m, 1H,
Ala-CH), 4.06 (m, 2H, CH2N), 4.17-4.34 (m, 2H, 2H-5′), 4.94,
4.97 (m, 1H, H-4′), 5.83 (m, 1H, H-2′), 6.21, 6.28 (dt, 1H, H-3′,
J 2′,3′ ) 6.0, 6.0 Hz, J 1′,3′ ) J 3′,4′ ) 1.8, 1.6 Hz), 7.00, 7.01 (m,
1H, H-1′), 7.08-7.28 (m, 6H, H-6, Ph); MS m/e FAB 585.0877
(MH+, C23H29BrN3O8P requires 585.0875).
5′-(P h en ylm eth oxyalan in yl)ph osph ate Th ym idin e (2d).
This synthesis was conducted in accordance with the procedure
reported by McGuigan et al.24,28 from thymidine and (phenyl-
methoxy)alaninyl phosphorochloridate. To a suspension of
thymidine (0.6 g, 2.47 mmol) in dry THF (9 mL) was added
N-methylimidazole (1.18 mL, 14.87 mmol). The resulting
solution was cooled to -20 °C, and phenyl methoxyalani-
nylphosphorochloridate (4.95 mmol) dissolved in THF (5 mL)
was slowly added. The clear solution became cloudy and slowly
demixed. The solution was stirred for 2 h at -20 °C and
overnight at room temperature. Water was added, and the
solvent was removed under reduced pressure. The residue was
dissolved in CHCl3 (25 mL) and washed with saturated NH4-
Cl (2 × 15 mL), water (15 mL), and brine (15 mL). The organic
phase was dried over Na2SO4, filtered, and concentrated to
dryness. The residue was purified by flash chromatography
on silica gel with dichloromethane/methanol, 10:1, to give
compound 2d as a white foam (0.49 g, 41%): HPLC Rt ) 5.51
min (40:60); 31P NMR (acetone-d6) 4.18, 4.39 ppm; 1H NMR
(acetone-d6) δ 1.32, 1.36 (d, 3H, Ala-CH3, J ) 7.1, 7.1 Hz), 1.80,
1.82 (d, 3H, CH3-5, J ) 1.1, 1.1 Hz), 2.15 (m, 2H, 2H-2′), 3.65
(s, 3H, Ala-OCH3), 4.11-4.56 (m, 5H, H-3′, H-4′, 2H-5′, Ala-
CH), 4.59, 5.00 (2m, 2H, OH, Ala-NH), 6.32 (m, 1H, H-1′),
7.24-7.37 (m, 5H, Ph), 7.57, 7.60 (d, 1H, H-6, J ) 1.1, 1.1 Hz),
9.98 (bs, 1H, NH-3); MS m/e FAB 483.1414 (MH+, C20H26N3O9P
requires 483.1406).
3-N-(3-Br om opr opyl)th ym idin e-5′-(ph en ylm eth oxyalan -
in yl)p h osp h a te (3d ): reaction time 30 h; 5 equiv of 1,3-
dibromopropane; eluent dichloromethane/methanol, 10:1; yield
of 3d (55%) as a syrup; HPLC Rt ) 3.45 min (system A, 45:
55); 31P NMR (CDCl3) 3.66, 4.10 ppm; 1H NMR (CDCl3) δ 1.29,
1.29 (d, 3H, Ala-CH3, J ) 7.0, 7.1 Hz), 1.84 (d, 3H, CH3-5, J )
0.9 Hz), 1.97 (m, 1H, H-2′a), 2.14 (m, 2H, CH2), 2.27 (m, 1H,
H-2′b), 3.35 (t, 2H, CH2Br, J ) 6.9 Hz), 3.63, 3.65 (s, 3H, Ala-
OCH3), 3.59-3.77 (m, 1H, Ala-NH), 3.89-4.44 (m, 8H, CH2N,
H-3′, H-4′, 2H-5′, Ala-CH, OH), 6.20, 6.24 (t, 1H, H-1′, J 1′,2′a
)
J 1′,2′b ) 6.4, 6.3 Hz), 7.09-7.29 (m, 6H, Ph, H-6); MS m/e FAB
603.0987 (MH+, C23H31BrN3O9P requires 603.0980).
N-(6-Br om oh exyl)-2′,3′-d id eh yd r o-2′,3′-d id eoxyth ym i-
d in e (4a ): reaction time 10 h; 4 equiv of 1,6-dibromohexane;
eluent dichloromethane/methanol, 20:1; yield of 4a (75%) as
a syrup; 1H NMR (CDCl3) δ 1.36-1.63 (m, 6H, 3CH2), 1.79 (d,
3H, CH3-5, J ) 1.1 Hz), 1.85 (m, 2H, CH2), 3.50 (t, 2H, CH2-
Br, J ) 7.0 Hz), 3.83 (m, 4H, CH2N, 2H-5′), 4.17 (t, 1H, 5′-
OH, J ) 5.8 Hz), 4.85 (m, 1H, H-4′), 5.92 (m, 1H, H-2′), 6.42
(m, 1H, H-3′), 6.99 (m, 1H, H-1′), 7.77 (d, 1H, H-6). Anal.
(C16H23BrN2O4) C, H, N.
3′-Azido-3-N-(6-br om oh exyl)-3′-deoxyth ym idin e-5′-(ph e-
n ylm eth oxya la n in yl)p h osp h a te (4b): reaction time 6 h; 3