6346 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 20
Berlicki et al.
refrigerator. Precipitated product was collected by filtration
to yield 2.5 g (77%). 1H NMR (D2O): δ 1.82 (dt, JPH ) 11.3 Hz,
JHH ) 6.6 Hz, 2H, CH2P), 3.06 (dt, JPH ) 9.2 Hz, JHH ) 7.4
Hz, 2H, CH2N), 6.97 (d, J ) 546 Hz, 1H, PH). 31P NMR (D2O):
δ 25.7.
Methyl (2S)-2-Benzyloxycarbonylamino-4-[(2′-carbam-
oylethyl)(hydroxy)phosphinyl]butyrate (18). The com-
pound was synthesized in the same manner as 15 using
compound 12 (0.37 g, 1.0 mmol) and carbamoylethylphosphinic
acid58 (0.28 g, 2.0 mmol) to yield 70 mg (18%). 1H NMR (D2O):
δ 1.63-1.96 (m, 6H, CHCH2CH2PCH2), 2.45 (m, 2H, CH2-
CONH2) 3.60 (s, OCH3), 4.15 (t, J ) 5.4 Hz, CH), 4.98 (s, 2H,
PhCH2O), 7.28 (m, 5H, C6H5). 31P NMR (D2O): δ 57.15.
Methyl (2S)-2-Amino-4-[(aminomethyl)(hydroxy)phos-
phinyl]butyrate (28). Compound 8 (0.46 g, 2.0 mmol) and
hexamethyldisilazane (7.0 mL) were heated at 90 °C for 1 h
under inert nitrogen atmosphere. Then, the solution was cooled
to 0 °C and compound 12 (0.37 g, 1.0 mmol) was added.
Mixture was heated at 80 °C during 6 h. After cooling to room
temperature, methanol (30 mL) was added and solution was
additionally stirred for 1 h. Solid impurities were filtered off,
and the solution was evaporated under reduced pressure. A
mixture of compounds 25 and 27 was isolated using HPLC
(water/acetonitrile). The obtained compounds were dissolved
in methanol (10 mL) and hydrogenated over palladium catalyst
(10% Pd/C, 30 mg) during 2 h. The catalyst was filtered off
and filtrate evaporated. Residue was separated using HPLC
(water/acetonitrile) to yield 5.3 mg (1.2%) of compound 28 and
4.0 mg (1.6%) of compound 29. Compound 28. 1H NMR (D2O):
δ 1.66 (m, 2H, CHCH2CH2P), 2.09 (m, 2H, CHCH2), 2.97 (d, J
) 9.3 Hz, 2H, NH2CH2P), 3.75 (s, 3H, OCH3), 4.12 (t, J ) 6.3
Hz, 1H, CH). 31P NMR (D2O): δ 32.02.
N-Benzyloxycarbonyl-2-aminoethylphosphinic Acid
(11). The compound was obtained from 10 (1.6 g, 14 mmol)
and benzyl chloroformate (2.7 mL, 19 mmol) using the same
1
procedure as for compound 8 to yield 1.85 g (54%). H NMR
(D2O): δ 1.61 (dt, JPH ) 15 Hz, JHH ) 7.3 Hz, 2H, CH2P), 3.17
(dt, JPH ) 11.2 Hz, JHH ) 8.0 Hz, 2H, CH2N), 4.95 (s, 2H,
PhCH2), 6.82 (d, JPH ) 510 Hz, 1H, PH), 7.27 (m, 5H, C6H5).
31P NMR (D2O): δ 27.2.
Methyl (2S)-2-Benzyloxycarbonylamino-4-(hydroxy-
methyl(hydroxy)phosphino)butyrate (15). Hexamethyl-
disilazane (7.0 mL) was added to hydroxymethylphosphinic
acid56 (0.25 g, 2.5 mmol) and the mixture was heated at 90 °C
for 2 h in nitrogen atmosphere. Then solution was cooled to 0
°C and compound 12 (0.37 g, 1.0 mmol) was added. The
mixture was heated at 90 °C for 6 h, and after cooling to room
temperature, methanol (30 mL) was added and stirring was
continued for 1 h. Solid impurities were filtered off, and the
solution was evaporated under reduced pressure. Products
were purified using HPLC (water/acetonitrile) to yield 60 mg
of compound 15 (17%), 15 mg of compound 19 (8%), and 10
mg of compound 23 (6%). Compound 15. 1H NMR (D2O): δ
1.65 (m, 2H, CH2CH2P), 1.76, 1.95 (m each, 1H and 1H,
CHCH2), 3.57 (s, 3H, OCH3), 3.61 (d, J ) 5.2 Hz, CH2OH),
4.10 (t, J ) 5.3 Hz, 1H, CH), 4.96 (s, 2H, PhCH2), 7.24-7.27
(m, 5H, C6H5). 31P NMR (D2O): δ 49.8.
Aminomethyl(hydroxymethyl)phosphinic Acid (29).
1H NMR (D2O): δ 3.12 (d, J ) 10.2 Hz, 2H, PCH2NH2), 3.33
(d, J ) 9.4 Hz, 2H, PCH2OH). 31P NMR (D2O): δ 20.07.
P-Benzylhydroxymethylphosphinic Acid (19). 1H NMR
(D2O): δ 3.05 (d, J ) 16.6 Hz, 2H, PhCH2), 3.55 (d, J ) 5.2
Hz, 2H, CH2OH), 7.14-7.24 (m, 5H, C6H5). 31P NMR (D2O): δ
46.2.
Methyl 2-Aza-4-oxa-3-oxocyclohexanecarboxylate (23).
1H NMR (D2O): δ 2.14-2.22, 2.32-2.40 (m each, 1H and 1H,
CHCH2), 3.16 (t, J ) 7.1 Hz, 2H, CH2CH2O), 4.68 (s, 3H,
OCH3), 4.07 (t, J ) 6.6 Hz, 1H, CH).
(2S)-2-Amino-4-[(hydroxymethyl)(hydroxy)phosphinyl]-
butyric Acid (3). Compound 15 (60 mg) was dissolved in
methanol (10 mL) and hydrogenated over palladium catalyst
(10% Pd/C, 10 mg) for 3 h. The catalyst was filtered off and
filtrate evaporated. Dry residue was dissolved in concentrated
HCl (10 mL) and refluxed for 8 h. Solvent was evaporated
under reduced pressure and the product was purified by means
1
of HPLC (water/acetonitrile) to yield 38 mg (94%). H NMR
(D2O): δ 1.84 (m, 2H, CHCH2CH2P), 2.11 (m, 2H, CHCH2-
CH2P), 3.75 (d, J ) 5.0 Hz, 2H, CH2OH), 4.07 (t, J ) 5.0 Hz,
1H, CH). 31P NMR (D2O): δ 46.2. 13C NMR (D2O): δ 21.60 (d,
JPC ) 89.5 Hz, CH2CH2P), 22.20 (CHCH2), 52.82 (d, JPC ) 15.4
Hz, CH), 58.05 (d, JPC ) 110.6 Hz, PCH2OH), 170.96 (COOH).
HPLC purity >97%.
Methyl (2S)-2-Benzyloxycarbonylamino-4-[(1′-benzyl-
oxycarbonylaminoethyl)(hydroxy)phosphinyl]butyrate
(16). The compound was synthesized in the same way as 15
using compound 12 (0.37 g, 1.0 mmol) and N-benzyloxycar-
bonyl-1-aminoethylphosphinic acid (0.40 g, 1.6 mmol) to yield
45 mg (9%) of compound 16 and 25 mg (7%) of compound 20.
Compound 16. 1H NMR (D2O): δ 1.30 (dd, JPH ) 14.6 Hz, JHH
) 7.0 Hz, 3H, CHCH3), 1.75 (m, 2H, CH2P), 1.85, 2.15 (m each,
1H and 1H, CHCH2), 3.69 (s, 3H, OCH3), 4.03, 4.32 (m each,
1H and 1H, 2 × CH), 4.91-5.11 (m, 4H, 2 × PhCH2), 5.62 (dd,
JPH ) 19.9 Hz, JHH ) 9.1 Hz, 1H, PCHNH), 5.94 (d, J ) 8.7
Hz, 1H, CH2CHNH), 7.24-7.32 (m, 10H, 2 × C6H5). 31P NMR
(D2O): δ 56.04, 56.48 (two diastereomers, molar ratio 1:1).
P-Benzyl-1-benzyloxycarbonylaminoethylphosphin-
(2S)-2-Amino-4-[(1′-aminoethyl)(hydroxy)phosphinyl]-
butyric Acid (4). A solution of 30% HBr in acetic acid (3 mL)
was added to compound 16 (40 mg) and the mixture was
stirred for 12 h at room temperature. Then solution was
evaporated under reduced pressure. Dry residue was dissolved
in concentrated HCl (10 mL) and refluxed for 8 h. Solvent was
evaporated under reduced pressure and the product was
purified by means of HPLC (water/acetonitrile) to yield 21 mg
1
1
(88%). H NMR (D2O): δ 1.35 (dd, JPH ) 12.0 Hz, JHH ) 6.4
ic Acid (20). H NMR (D2O): δ 1.15 (dd, JPH ) 14.5 Hz, JHH
Hz, 3H, CHCH3), 1.72 (m, 2H, CH2P), 2.14 (m, 2H, CHCH2-
CH2), 3.31 (m, 1H, CHCH3), 4.04 (t, J ) 6.3 Hz, 1H, CHCH2).
31P NMR (D2O): δ 36.01. 13C NMR (D2O): δ 12.80 (CH3), 22.76
) 7.2 Hz, 3H, CHCH3), 2.99 (d, J ) 15.9 Hz, 2H, PhCH2P),
3.96 (dt, J ) 7.7 Hz, J ) 5.5 Hz, 1H, CH), 5.07 (s, 2H,
PhCH2O), 5.11 (m, 1H, NH), 7.18-7.32 (m, 10H, 2 × C6H5).
31P NMR (D2O): δ 52.30 (90%) and 51.40 (10%) (trans and cis
isomers).62
(CHCH2), 23.15 (d, JPC ) 93.8 Hz, CH2CH2P), 45.77 (d, JPC
)
94.9 Hz, CHP), 53.60 (CHCOOH), 172.02 (COOH). HPLC
purity >97%.
Methyl (2S)-2-Benzyloxycarbonylamino-4-[(2′-benzyl-
oxycarbonylaminoethyl) (hydroxy)phosphinyl]butyrate
(17). The compound was synthesized in the same way as 15
using compound 12 (0.37 g, 1.0 mmol) and compound 11 (0.49
g, 2.0 mmol) to yield 40 mg (8%) of compound 17 and 25 mg
(2S)-2-Amino-4-[(2′-Aminoethyl)(hydroxy)phosphinyl]-
butyric Acid (5). The compound was synthesized from 17 (40
mg) using the same procedure as for 4 to yield 15 mg (65%).
1H NMR (D2O): δ 1.78 (m, 2H, CHCH2CH2P), 2.06 (m, 4H,
NCH2CH2PCH2CH2CH), 3.17 (dt, JPH ) 7.2 Hz, JHH ) 8.4 Hz,
2H, CH2NH2), 4.10 (t, J ) 5.7 Hz, 1H, CH). 31P NMR (D2O):
δ 47.3. 13C NMR (D2O): δ 22.45 (CHCH2), 24.60 (d, JPC ) 93.0
Hz, CHCH2CH2P), 25.67 (d, JPC ) 90.4 Hz, NCH2CH2P), 33.87
(CH2CH2N), 52.88 (d, JPC ) 16.0 Hz, CHCH2), 171.06 (COOH).
HPLC purity >97%.
1
(7%) of compound 21. Compound 17. H NMR (D2O): δ 1.42
(m, 2H, CHCH2CH2P), 1.65, 1.84 (m each, 1H and 1H, CHCH2),
1.65 (m, 2H, NHCH2CH2P), 3.16 (dt, JHH ) 8.3 Hz, JPH ) 7.3
Hz, 2H, CH2N), 3.25 (s, 3H, OCH3), 3.85 (m, 1H, CH), 5.00,
5.03 (s each, 2H and 2H, 2 × PhCH2O), 7.31 (m, 10H, 2 ×
C6H5). 31P NMR (D2O): δ 43.0.
P-Benzyl-2-benzyloxycarbonylaminoethylphosphin-
ic Acid (21). 1H NMR (D2O): δ 1.49 (m, 2H, CH2CH2P), 2.75
(d, J ) 17.2 Hz, PhCH2P), 3.03 (m, 2H, CH2CH2P), 4.90 (s,
2H, PhCH2O), 7.07-7.27 (m, 5H, C6H5). 31P NMR (D2O): δ
39.9.
(2S)-2-Amino-4-[(2′-Carboxyethyl)(hydroxy)phosphinyl]-
butyric Acid (24). The compound was synthesized from 18
(70 mg) using the same procedure as for 4 to yield 47 mg (95%).
1H NMR (D2O): δ 1.84 (m, 2H, CHCH2CH2P), 2.03 (dt, JPH
)
13.2 Hz, JHH ) 8.0 Hz, 2H, PCH2CH2COOH), 2.12 (m, 2H,