Peptidomimetic Conjugates of Cyclic HPMPC and HPMPA
brief articles
collected by filtration. The white crystals obtained were
carefully dried in vacuo. The final products were analyzed
37%). Mobile phase for first TLC purification: CH2Cl2/
CH3OH (6:1). Mobile phase for second TLC purification:
CH2Cl2/CH3OH (4:1). H NMR (400 MHz, CD3OD): δ )
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by H NMR and 31P NMR, HRMS, and LC-MS.
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1.32-1.37 (m, 6H), 3.77-4.63 (m, 11H), 5.11-5.20 (m,
1H), 5.90 (d, J ) 6.7 Hz, 1H), 7.55 (d, J ) 6.7 Hz, 0.8H),
7.60 (d, J ) 6.7 Hz, 0.2H). 31P NMR (202 MHz, CD3OD):
δ ) 14.63 (s, 0.78P), 15.51 (s, 0.22P). HRMS-FAB m/z [M
+ H]+ calcd for C14H23N4O7P: 391.1377, found 391.1380.
LC-MS: tR ) 9.22 min; [M + H]+ 391.1.
Methyl L-Valyl-O-{(5S)-5-[(4-amino-2-oxopyrimidin-1(2H)-
yl)methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-L-serinate (2a).
2a was obtained from 100 mg of HPMPC and 131 mg of
11a using general method C, as a white powder (123 mg,
56%). Mobile phase for first TLC purification: CH2Cl2/
CH3OH (6:1). Mobile phase for second TLC purification:
CH2Cl2/CH3OH (10:3). 1H NMR (400 MHz, CD3OD): δ )
1.09-1.16 (m, 6H), 2.22-2.34 (m, 1H), 3.78-4.60 (m,
14H), 5.91-5.94 (brs, 1H), 7.60 (d, J ) 7.4 Hz, 0.7H), 7.65
(d, J ) 7.4 Hz, 0.3H). 31P NMR (202 MHz, CD3OD): δ )
Isopropyl O-{(5S)-5-[(4-Amino-2-oxopyrimidin-1(2H)-yl)-
methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-D-serinate (3b).
3b was obtained from 150 mg of HPMPC and 176 mg of
12b using general method C, as a white powder (62 mg,
21%). Mobile phase for first TLC purification: CH2Cl2/
CH3OH (9:1). Mobile phase for second TLC purification:
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14.41 (s, 0.65P), 15.53 (s, 0.35P). The H and 31P NMR
chemical shift values are similar to those previously reported
for the same compound.4 LC-MS: tR ) 9.83 and 11.17 min;
[M + H]+ 462.1.
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CH2Cl2/CH3OH (10:2.7). H NMR (400 MHz, CD3OD): δ
) 1.35-1.38 (m, 6H), 3.74-4.70 (m, 11H), 5.14-5.22 (m,
1H), 5.90 (d, J ) 7.3 Hz, 1H), 7.52 (d, J ) 7.3 Hz, 0.8H),
7.59 (d, J ) 7.3 Hz, 0.2H). 31P NMR (202 MHz, CD3OD):
δ ) 14.51 (s, 0.80P), 15.73 (s, 0.20P). HRMS-FAB m/z [M
+ H]+ calcd for C14H23N4O7P: 391.1377, found 391.1381.
Methyl L-Valyl-O-{(5S)-5-[(4-amino-2-oxopyrimidin-1(2H)-
yl)methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-D-serinate (2b).
2b was obtained from 100 mg of HPMPC and 152 mg of
11b using general method C, as a white powder (47 mg,
22%). Mobile phase for first TLC purification: CH2Cl2/
CH3OH (6:1). Mobile phase for second TLC purification:
Isopropyl O-{(5S)-5-[(4-Amino-2-oxopyrimidin-1(2H)-yl)-
methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-L-seryl-L-alani-
nate (4). 4 was obtained from 150 mg of HPMPC and 257
mg of 13 using general method C, as a white powder (172
mg, 53%). Mobile phase for first TLC purification: CH2Cl2/
CH3OH (8:1). Mobile phase for second TLC purification:
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CH2Cl2/CH3OH (4:1). H NMR (400 MHz, CD3OD): δ )
1.06-1.14 (m, 6H), 2.26 (m, 1H), 3.79-4.58 (m, 14H), 5.88
(d, J ) 7.3 Hz, 1H), 7.53 (d, J ) 7.3 Hz, 0.7H), 7.57 (d, J
) 7.5 Hz, 0.3H). 31P NMR (202 MHz, CD3OD): δ ) 14.40
(s, 0.7P), 15.68 (s, 0.3P).
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CH2Cl2/CH3OH (4:1). H NMR (400 MHz, CD3OD): δ )
Methyl D-Valyl-O-{(5S)-5-[(4-amino-2-oxopyrimidin-1(2H)-
yl)methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-L-serinate (2c).
2c was obtained from 300 mg of HPMPC and 455 mg of
11c using general method C, as a white solid (378 mg, 58%).
Mobile phase for first TLC purification: CH2Cl2/CH3OH (6:
1). Mobile phase for second TLC purification: CH2Cl2/
CH3OH (10:3). 1H NMR (400 MHz, CD3OD): δ ) 1.07-1.13
(m, 6H), 2.25 (m, 1H), 3.75-4.58 (m, 14H), 5.92 (d, J )
7.3 Hz, 0.7H), 5.92 (d, J ) 7.5 Hz, 0.3H), 7.59 (d, J ) 7.3
Hz, 0.7H), 7.64 (d, J ) 7.5 Hz, 0.3H). 31P NMR (202 MHz,
CD3OD): δ ) 14.21 (s, 0.8P), 15.26 (s, 0.2P).
Methyl D-Valyl-O-{(5S)-5-[(4-amino-2-oxopyrimidin-1(2H)-
yl)methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-D-serinate (2d).
2d was obtained from 200 mg of HPMPC and 321 mg of
11d using general method C, as a white powder (199 mg,
45%). Mobile phase for first TLC purification: CH2Cl2/
CH3OH (6:1). Mobile phase for second TLC purification:
CH2Cl2/CH3OH (10:3). 1H NMR (400 MHz, CD3OD): δ )
1.09-1.16 (m, 6H), 2.29 (m, 1H), 3.78-4.57 (m, 14H), 5.89
(d, J ) 7.5 Hz, 0.3H), 5.89 (d, J ) 7.3 Hz, 0.7H), 7.53 (d,
J ) 7.3 Hz, 0.7H), 7.57 (d, J ) 7.5 Hz, 0.3H). 31P NMR
(202 MHz, CD3OD): δ ) 14.77 (s, 0.7P), 15.73 (s, 0.3P).
MS-ESI m/z [M + H]+ calcd for C17H28N5O8P: 462.18, found
462.18. LC-MS: tR ) 13.34 and 14.88 min; [M + H]+
462.1.
1.27-1.31 (m, 6H), 1.44 and 1.47 (2d, J ) 7.4 and 7.4 Hz,
3H), 3.75-4.64 (m, 11H), 5.01-5.07 (m, 1H), 6.00 (d, J )
7.5 Hz, 1H), 7.72 (d, J ) 7.5 Hz, 0.6H), 7.77 (d, J ) 7.5
Hz, 0.4H). 31P NMR (202 MHz, CD3OD): δ ) 14.98 (s,
0.57P), 16.26 (s, 0.43P). HRMS-FAB m/z [M + H]+ calcd
for C17H28N5O8P: 462.1748, found 462.1752. LC-MS: tR
) 12.99 and 13.18 min; [M + H]+ 462.2.
General Method D. TBDMS Protection of Serine
Methyl and Isopropyl Esters. Serine methyl ester hydro-
chloride or serine isopropyl ester hydrochloride (9a) (2.3
mmol, 1 equiv) and tert-butylchlorodimethylsilane (4.8
mmol, 2.1 equiv) were dissolved in 20 mL of dry CH2Cl2.
The reaction mixture was cooled to 0 °C before addition of
imidazole (7.1 mmol, 3.1 equiv). The reaction mixture was
stirred overnight at rt. An additional 100 mL of CH2Cl2 was
added to the reaction mixture, and the organic layer was
washed with a saturated citric acid solution (25 mL) and
saturated NaHCO3 solution (25 mL). Combined water phases
were extracted twice with 30 mL of CH2Cl2 (to increase the
yield, product as a salt is soluble in water). All organic phases
were combined and dried over Na2SO4 and concentrated
under reduced pressure yielding a white solid. The solid was
washed on a filter with 20 mL of hexanes to remove the
TBDMSOH, giving a clean product.
Isopropyl O-[tert-Butyl(dimethyl)silyl]-L-serinate (14). 14
was obtained using general method D (521 mg, 76%). H
NMR (400 MHz, CDCl3): δ ) 0.08 (s, 3H), 0.12 (s, 3H),
0.88 (s, 9H), 1.29 (d, J ) 6.4 Hz, 6H), 4.13 (dd, J ) 2.6
Isopropyl O-{(5S)-5-[(4-Amino-2-oxopyrimidin-1(2H)-yl)-
methyl]-2-oxido-1,4,2-dioxaphosphinan-2-yl}-L-serinate (3a).
3a was obtained from 150 mg of HPMPC and 176 mg of
12a using general method C, as a white powder (110 mg,
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VOL. 7, NO. 6 MOLECULAR PHARMACEUTICS 2353