2'C-alkoxy and 2'-C-aryloxy derivatives of N-(2-phosphonomethoxyethyl)-purines and -pyrimidines: synthesis and biological activity.

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2′-C-ALKOXY AND 2′-C-ARYLOXY DERIVATIVES OF

N-(2-PHOSPHONOMETHOXYETHYL)-PURINES AND -

PYRIMIDINES: SYNTHESIS AND BIOLOGICAL ACTIVITY

Dominik Rejman ^a, Milena Masojídková ^a, Eric De Clercq ^b& Ivan Rosenberg ^a

^aInstitute of Organic Chemistry and Biochemistry, Academy of Science of the Czech

Republic , Flemingovo n. 2, Prague 6, 166 10, Czech Republic

^bRega Institute for Medical Research, Katholieke Universiteit Leuven ,

Minderbroedersstraat, 10, Leuven, B-3000, Belgium

Published online: 17 Aug 2006.

To cite this article: Dominik Rejman , Milena Masojídková , Eric De Clercq & Ivan Rosenberg (2001) 2′-C-ALKOXY AND 2′-

C-ARYLOXY DERIVATIVES OF N-(2-PHOSPHONOMETHOXYETHYL)-PURINES AND -PYRIMIDINES: SYNTHESIS AND BIOLOGICAL

ACTIVITY, Nucleosides, Nucleotides and Nucleic Acids, 20:8, 1497-1522, DOI: 10.1081/NCN-100105244

To link to this article: http://dx.doi.org/10.1081/NCN-100105244

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NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS, 20(8), 149771522 (2001)

2⁰-C-ALKOXY AND 2⁰-C-ARYLOXY DERIVATIVES

OF N-(2-PHOSPHONOMETHOXYETHYL)-

PURINES AND -PYRIMIDINES: SYNTHESIS AND

BIOLOGICAL ACTIVITY

1

DominikRejman, Milena Masojõdkova,¹Eric De Clercq,²and

Ivan Rosenberg¹

¹Institute of Organic Chemistry and Biochemistry,

Academy of Science of the Czech Republic, Flemingovo n.2,

166 10 Prague 6, Czech Republic

²Rega Institute for Medical Research, Katholieke Universiteit

Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium

ABSTRACT

A series of novel, unusual type of acyclic phosphonate-based nucleotide

analogues related to well-known antivirals (PMEA and HPMPA) was

synthesized using easily available synthon.These compounds, which are

distinguished for the presence of phosphonomethyl acetal linkage, form a

group of derivatives that contribute to the understanding of structure-

activity relationship within the area of acyclic nucleotide analogues.

The N-(2-phosphonomethoxyethyl)purines 1 (PME-derivatives) are

known to strongly inhibit DNA viruses and retroviruses^1,2.Modi®cation

of the side-chain of PME-derivatives strongly in¯uences the selectivity in

antiviral properties of the compounds.Thus, N-(3-hydroxy-2-phosphono-

methoxypropyl)purines 2 act solely on DNA viruses¹, while N-(3-¯uoro-2-

phosphonomethoxypropyl)purines 3 and N-(2-phosphonomethoxypropyl)-

purines 4 aect exclusively retroviruses^3,4.The activity of compounds

4

corresponds to the ¯uoro derivatives 3 both in base speci®city and require-

ment on a con®guration⁴.

In the frame of structure-activity study of acyclic nucleotide analogs, we

report herein the synthesis of a novel group of compounds related to known

1497

Copyright # 2001 by Marcel Dekker, Inc.

www.dekker.com

1498

REJMAN ET AL.

Figure 1. Inhibitors of replication of DNA viruses and retroviruses.

Figure 2. Prepared 2-C-substituted PME-derivatives.

Table 1. Prepared 2-C-Substituted PME-Derivatives of Nucleobases (for structures see

Figure 2)

Comp

B

R

Comp

B

R

17a

17b

17c

17d

adenine

1-adamantanyl

2-azidoethyl

benzyl

19c

19d

2,6-diaminopurine 2-fluoroethyl

2,6-diaminopurine 2-hydroxyethyl

tert-butyl

20a

20b

20c

2-amino-

6-bromopurine

2-amino-

6-bromopurine

2-amino-

6-bromopurine

allyl

17e

17f

17g

adenine

cyclohexyl

2-benzoyloxy-

ethyl

2-fluoroethyl

8-hydroxy-3,6-

dioxaoctyl

17h

17i

17j

17k

17l

18a

18b

18c

adenine

cytosine

2-hydroxyethyl

methyl

n-octyl

phosphonomethyl

2,2,2-trifluoroethyl

allyl

2-fluoroethyl

methyl

21a

21b

21c

guanine

allyl

2-fluoroethyl

2-hydroxyethyl

22

adenine

cytosine

2,6-diaminopurine

guanine

thymine

7

23a

23b

23c

23d

23e

19a

19b

2,6-diamino- 2-azidoethyl

purine

2,6-diamino- 2-benzoyloxyethyl

purine

23f

uracil

7

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1499

antivirals 1-4.In order to investigate the in¯uence of a substituent in the

2-position of the side chain in PME-compounds on the antiviral activity, we

elaborated the synthesis of racemic 2-C-alkoxy 17a-l, 18a-c, 19a-d, 20a-c,

21a-c, 2-C-phenylthio 22, 2-C-phenyloxy 23a-f, and 2-C-azido 24 derivatives

(Figure 1; for R and B see Table 1).

For the preparation of these compounds, the reaction of nucleobase

with an appropriate phosphonate moiety-containing synthon 7, 11, 13 and 15

(Scheme 1) was used.A key, starting compound for the preparation of

synthons, the diisopropyl vinyloxymethanephosphonate (6), was obtained in

a high yield by b-elimination of hydrogen chloride from diisopropyl 2-

chloroethoxymethanephosphonate (5) by treatment with potassium tert-

butoxide.The compound 5 is easily accessible by Arbuzov reaction of the

2-chloroethylchloromethyl ether with tris-triisopropyl phosphite⁵.

Thus, the reaction of vinyloxymethanephosphonate 6 with various

hydroxy compounds R-OH (for R see Table 1) and N-iodosuccinimide (not

N-bromosuccinimide) has led to the phosphonate synthons 7 and 13; this

type of electrophile-promoted addition of nucleophiles to a vinyl ether

Scheme 1. Synthetic pathway for 2-C-substituted PME-derivatives of nucleobases.

1500

REJMAN ET AL.

moiety was already described⁶.Since the silica gel chromatography of several

crude iodo derivatives 7 did not lead to their satisfactory puri®cation,

probably because of low stability, they were used for the further reaction step

without chromatography.

Similarly, the preparation of synthons 11a, 11b containing phenoxy and

phenylthio moiety starting from vinyloxymethanephosphonate 6 was elabo-

rated.Reaction of this compound with bromine resulted in the disopropyl

1,2-dibromoethoxymethanephosphonate (9) in which the 1-bromo atom

underwent nucleophilic displacement by phenoxy or phenylthio group.

We succeeded at the preparation of azido synthon 13, although, in a

very low yield in the reaction of iodoazide (generated in situ from sodium

azide and iodochloride 7) with vinyloxymethanephosphonate 6 in dimethyl-

formamide.The reaction of the formed 1-azido-2-iodoethoxymethanepho-

sphonate 13 with sodium salt of adenine at room temperature aorded, after

deblocking procedure, the expected phosphonate 24⁸.

The alkylation of nucleobases (thymine, cytosine, adenine, 2,6-diami-

nopurine and 2-amino-6-chloropurine) by the appropriate phosphonate

synthons 7, 11 and 13 in the presence of cesium carbonate was performed in

DMF at elevated temperature.

Phenylthio derivative 22 was obtained in very low yield by alkylation of

sodium salt of adenine with compound 11b at room temperature.When

performed at 100 ^ꢀC and in the presence of cesium carbonate, the reaction

aorded tetraisopropyl 2-phenylthio-1,1-bis(phosphonomethoxy)ethane (10)

as the only major product (its formation is unclear).

All obtained diesters 8 and 12 were puri®ed by silica gel chromato-

graphy and subjected, without characterization, to the transesteri®cation

procedure with bromotrimethylsilane.Thus, the free phosphonates 17a-g,

17i-l, 18a-c, 19a-c, 20a-c, 22, and 23a-c,e,f (Table 1) were prepared by this

procedure directly whereas the phosphonates 17h and 19d were obtained

after debenzoylation of the O-benzoyl derivative of compound 17h and the

O-benzoyl derivative 19b under alkaline conditions.The guanine derivatives

21a-c were prepared by hydrolysis of their 2-amino-6-bromopurine con-

geners 20a-c in aqueous sodium hydroxide.The bromo compounds 20a-c

(con®rmed by MS) were obtained unexpectedly during removal of the

phosphonate diester moiety of the corresponding 2-amino-6-chloropurine

derivatives by bromotrimethylsilane.To our knowledge, such exchange

reaction of the 6-chloro atom for 6-bromo one in guanine derivatives has not

been described so far in the literature.

We elaborated another approach for the preparation of phosphonate

synthon(s) useful for subsequent reaction with nucleobases.Reaction of

vinyloxymethanephosphonate 6 with the 3-chloroperoxybenzoic acid has led

to epoxide 14 which underwent, in the presence of n-octanol, epoxide ring-

opening to aorddiisopropyl 2-hydroxy-1-octyloxyethoxymethane-phospho-

nate (15) in a good yield.The absence of n-octanol in the reaction mixture has

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1501

led to diisopropyl 1-(3-chlorobenzoyloxy)-2-hydroxyethoxymethanephos-

phonate (16).Mitsunobu alkylation of derivative 15 with 6-N-dibutylamino-

methylenadenine gave a low yield of 6-N-dibutylaminomethylene-9-N-(2-

(diisopropylphosphonomethoxy)-2-octyl-oxyethyl)adenine.MS FAB and UV

spectroscopy data supported the proposed structure of this compound.

In order to elaborate general approach allowing for the preparation of

``universal'' phosphonate synthons containing O,O-, O,N and O,S mixed

acetals with phosphonomethyl moiety (like compounds 7, 11 and 13), we

synthesized diisopropyl 1-acetoxy-2-iodomethanephosphonate (52) from

vinylacetate (50) and diisopropyl hydroxymethanephosphonate (51)⁹in the

presence of N-iodosuccinimide (Scheme 2) intended to replace the acetoxy

group for hydroxy, amino or thiol function.Our attempt to prepare the

compound 53 from 1-N-trimethylsilylimidazole as the nucleophile and

compound 52 in the presence of trimethylsilyl tri¯ate completely failed.

A thorough study on the conditions of the reaction of compound 52 with the

various O-, S- and N-nucleo®les and Lewis acid catalysts is underway.

Concerning the biological activity of prepared acyclic phosphonate

nucleotides, we found neither cytostatic eects of compounds 17723 using

three cell lines (L929, L1210 and HeLa) nor anticancer activities of phos-

phonates 23a-f, as evaluated also in three cell lines as well [NCI-H460

(Lung), MCF7 (Breast), and SF-268 (CNS)].A thorough structure-activity

study on the prepared nucleotides revealed only three compounds (19c, 21b

and 22) out of thirty-two to exhibit a marginal antiviral activity against DNA

viruses and retroviruses (Table 2).In the light of these ®ndings we can

conclude that substitution of PME-derivatives of nucleobases at the 2-posi-

tion of their side chain by alkoxy or phenoxy substituents does not lead,

under currently used screening conditions, to antiviral=anticancer activities.

Since there is no data on cellular uptake of novel nucleotides, some of them

will be subjected to a detailed study aimed at this evaluation.

EXPERIMENTAL

Unless stated otherwise, the solutions were evaporated at 40 ^ꢀC and

2 kPa.Purity of the products was checked by chromatographic methods

Scheme 2. Preparation of ``universal'' synthon.

1502

REJMAN ET AL.

Table 2. Antiviral Properties of Prepared Compounds

Anti-HIV Activity^b

EC₅₀(mg=ml)^c

Antiviral Activity IC₅₀(mg=ml)^a

À

TK VZV (strains)

T K

(strains)

V Z V

OKA

YS

07=1

YS=R

HIV-1

HIV-2

Compound

19c

21b

>50

5.6

>50

0.78

0.0031

>50

2.6

> 50

27

>50

100

33.3 Æ 23.1

53.3 Æ 41.6

7

40.0 Æ 0.0

7.67 Æ 4.04

33.3 Æ 11.5

7

3.7

2.0

29

22

ACV^d

BVDU^e

0.93

0.0084

7

^ainhibitory concentration required to reduce virus plaque formation by 50%.Virus input was 20

b

c

plaque forming units (PFU); performed in human T-lymphocyte (CEM cells); 50% effective

concentration or concentration required to protect CEM cells against the cytopathogenicity of

d

e

HIV by 50% 9-(2-hydroxyethoxymethyl)guanine; 5-(2-(Z)-bromovinyl)-2⁰-deoxyuridine.

(TLC, HPLC) and spectral methods (NMR, MS, UV).All the described

reactions were monitored by TLC on Silufol UV 254 foils (Kavalier Glass-

works, Votice, Czech Republic).The compounds were detected both by UV

monitoring and by spraying with 1% ethanolic solution of 4-(4-nitro-

benzyl)pyridine (PNBP) whereby, after short heating and exposing to

ammonia vapours, the product (phosphonate diester) aorded intensively

blue spot.Preparative column chromatography (diameter, 50 mm) was car-

ried out on 40760 mm silica gel (Fluka), the amount of adsorbent was 20740

times the weight of the separated mixture.Elution was performed at the ¯ow

rate of 40 ml=min.Mass spectra were recorded on ZAB-EQ (VG Analytical)

instrument, using FAB (ionization with Xe, accelerating voltage 8 kV).

Glycerol and thioglycerol were used as matrices.NMR spectra were mea-

sured on Varian Unity 500 instrument (¹H at 500 MHz,¹³C at 125.7 MHz) in

hexadeuteriodimethylsulfoxide (DMSO-d₆) or deuterized water and refer-

enced to the solvent signal standard (d_H 2:5, d_C 39:7).

Diisopropyl 2-Chloroethoxymethanephosphonate (5)

Mild stream of hydrogen chloride was passed through a suspension

of paraformaldehyde (112 g, 3.73 mol) in 2-chloroethanol (250 ml,

3.73 mol) at 0 ^ꢀC until paraformaldehyde had dissolved (ꢁ 4 h).After

separation of aqueous layer, the crude 2-chloroethyl chloromethyl ether

was dried over anhydrous CaCl₂under stirring for 30 min, then ®ltered,

and the solid portion was washed with dichloromethane.Filtrates were

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1503

combined and the dissolved hydrogen chloride was removed in vacuo at

room temperature.The 2-chloroethyl chloromethyl ether was puri®ed by

distillation (b.p. 1457147 ^ꢀC=760 torr) under argon atmosphere.Yield,

276.9 g (46%).

Triisopropyl phosphite (230 g, 1.1 mol) was added dropwise during

30 min under vigorous stirring to the 2-chloroethyl chloromethyl ether

(117.66 g, 0.92 mol) at 120 ^ꢀC.The mixture was then heated at 120 ^ꢀC for

additional 4 hours.The isopropylchloride evolving during reaction was

continuously distilled o using a recti®cation head.The crude diisopropyl 2-

chloroethoxymethanephosphonate (5) was puri®ed by distillation at reduced

pressure (b.p. 115 ^ꢀC=0.15 torr). Yield, 207.4 g (80.2%).

Anal.calcd.for C ₉H₂₀ClO₄P (258.68): C, 41.79, H, 7.79. Found: C,

42.08, H, 8.27. MS (FAB): 259.1 (MH ).¹H NMR (DMSO-d₆): 4.61 (2H, d

sept, J_CH,CH 6.1, J_P,OCH 7.8, P-OCH), 3.80 (2H, d, J_P,CH 8.5, P-CH₂),

3

3.78-3.72 (4H, m, O-CH₂and CH₂Cl), 1.25 (6H, d, CH₃), 1.245 (6H, d,

J_CH,_CH

6.1, CH₃).¹³C NMR (DMSO-d₆): 70.44 (d, J_P,C 11.7, O-C), 70.39

3

(d, J_P,C 6.8, P-OC), 64.78 (d, J_P,C 165.0, P-C), 43.36 (C-Cl), 24.01 (d,

J_P,C 3.9, CH₃), 23.89 (d, J_P,C 4.9, CH₃).

Diisopropyl Vinyloxymethanephosphonate (6)

Potassium tert-butoxide (9 g, 80 mmol) was added under argon to a

vigorously stirred solution of the diisopropyl 2-chloroethoxymethanepho-

sphonate (5) (18.1 g, 70 mmol) in tetrahydrofuran (140 ml) at 0 ^ꢀC.The ice

bath was then removed and the mixture was stirred at room temperature

for further 20 min.TLC on the silica gel plate performed in toluene-

ethylacetate (1:1) revealed disappearance of the starting material and for-

mation of a new product (R_fvalues of both compounds have very little

dierence) as detected on both PNBP and potassium permanganate

spraying.The mixture was concentrated in vacuo and semi-solid residue was

taken between ether and water.The ether layer was washed several times

with water, dried over anhydrous sodium sulfate, ®ltered, and the solvent

removed in vacuo.Distillation of the crude product at dimished pressure

aorded 13.67 g (87.9%) of diisopropyl vinyloxymethanephosphonate (6)

(60765 ^ꢀC, 0.02 torr).

Anal.calcd.for C ₉H₁₉O₄P.1=3H₂O (228.22): C, 47.36, H, 8.69. Found:

C, 47.24, H, 8.74. MS (FAB): 331 (M thioglycerol).¹H NMR (DMSO-

d₆): 6.53 (1H, dd, J_cis 6.6, J_trans 14.2, O-CH), 4.62 (2H, d sept,

J_CH,CH6.1, J_P,OCH7.8, P-OCH), 4.34 (1H, dd, J_g2.2, J_trans14.2, CH),

3

4.07 (1H, dd, J_g 2.2, J_cis 6.6, CH), 3.99 (2H, d, J_P,CH9.0, P-CH₂), 1.26

(6H, d, CH₃), 1.24 (6H, d, J_CH,_CH

(d, J_P,C 12.7, O-CH), 88.34 (CH₂), 70.71 (d, J_P,C 6.8, P-OC), 62.26

(d, J_P,C 168.0, P-C), 23.97 (d, CH₃), 23.85 (d, J_P,C 3.9, CH₃).

6.1, CH₃).¹³C NMR (DMSO-d₆): 152.36

3

1504

REJMAN ET AL.

General Procedures

Method A: Preparation of Synthons 7

N-iodosuccinimide (1.24 g, 5.5 mmol) was added to a solution of diiso-

propyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol) and hydroxy deri-

vative R-OH (for R, see TABLE1) (10 mmol) in dichloromethane at 0 ^ꢀC under

argon atmosphere.After 24 hours of stirring at room temperature, the reaction

mixture was washed with saturated aqueous solution of sodium hydro-

gencarbonate.The organic layer was dried with anhydrous sodium sulfate and

the solvent was evaporated.The crude products 7 and 13 were used without

further puri®cation and characterization for the subsequent reaction step.

Method B: Preparation of phosphonate diesters 8 and 12 (alkylation of

nucleobases)

Crude synthons 7 and 11 (ꢁ 5 mmol) (see Method A), dried by codis-

tillation with toluene (3 times) were treated in dimethylformamide (30 ml)

under stirring at 110 ^ꢀC with appropriate nucleobases (1 eq) in the presence of

cesium carbonate (1 eq) for 10 hours.The course of the reaction was checked

by TLC in ethyl acetate-acetone-ethanol-water (12:2:2:1) and detected using

both UV absorption and spraying by PNBP.The solvents were removed in

vacuo and the residue chromatographed on a silica gel column by a gradient

elution of ethanol in chloroform (0- > 10%).The resulting compounds 8 and

12, resp., were used for further reaction without characterization.

Deprotection of Phosphonate Diester 8 and 12

Method C: Preparation and Puri®cation of Free Acyclic Nucleotides 17a-g,

17i-l, 18a-c, 19a-c, 20a-c, 22, 23a-c,e,f and 24

The phosphonate diesters 8 and 12 (Method B) in acetonitrile (ꢁ 5 ml per

mmol) were treated with bromotrimethylsilane (ꢁ 3 equiv=mmol) at room

temperature overnight.The course of the reaction was checked by TLC in

isopropanol-conc.aqueous ammonia-water (7:1:2).The solution was eva-

porated and the solid residue dissolved in 0.1 M triethylammonium hydro-

gencarbonate in 50% aqueous methanol to hydrolyze ester trimethylsilyl

groups.After 30 min of standing at room temperature the solvents were

removed in vacuo and the crude free phosphonate was puri®ed on a column

of DEAE-Sephadex A25 (166200 mm) using

a

gradient elution

of triethylammonium hydrogencarbonate in water pH 7.5 (070.2 M,

261000 ml).Fractions containing the product were combined and evapo-

rated.The residue was codistilled several times with methanol to destroy the

excess of buer, and the pure phosphonate was converted into the sodium

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1505

salt on Dowex 50 (Na form) column.Adjustment of the compounds was

performed by lyophilisation from their aqueous solutions.

Method D: Preparation and Puri®cation of Free Acyclic Nucleotides 17h,

19d, 21a-c and 23d

The diisopropyl esters of compounds .17h, 19b, 20a-c and compound

12.(X O; B 2-amino-6-chloropurin-9-yl) in acetonitrile (ꢁ 5 ml per

mmol) were treated with bromotrimethylsilane (3 equiv=mmol) at room

temperature overnight.The solution was evaporated and the solid residue

dissolved in aqueous 0.2 M-sodium hydroxide (50 ml per mmol) to remove

the O-benzoyl group and to hydrolyze the 2-amino-6-halopurine derivatives

to guanine ones.After standing at room temperature for 16 hr the alkaline

solution was treated with Dowex 50 (triethylammonium form) (25 ml per

mmol) to remove sodium ions, and after ®ltering o the resin, the clear

solution was concentrated in vacuo.For puri®cation step see Method C.

Diisopropyl 2-bromo-1-phenylthioethoxymethanephosphonate (11b)

1 M solution of bromine (5.5 ml, 5.5 mmol of Br₂) in dichloromethane

was added dropwise during 30 min to the solution of diisopropyl vinylox-

ymethanephosphonate (6) (1.1 ml, 5 mmol) in dichloromethane (15 ml) at

À78 ^ꢀC under argon atmosphere.Solution of sodium thiophenolate in THF

(0.55 M, 10 ml) (prepared from thiophenol and sodium hydride) was then

added to the above mixture.The reaction was set aside at room temperature

overnight.The reaction mixture was diluted by dichloromethane (50 ml),

washed with saturated aqueous solution of sodium hydrogencarbonate, and

organic layer was evaporated.Crude product was isolated on silica gel

column by gradient elution of acetone (0750%) in toluene.Yield, 08.41 g

(40.9%) of compound 11b.

MS: 382.3 (MH ).¹H NMR (DMSO-d₆): 7.58-7.52 m, 2H a 7.42-7.35 m,

3H (arom H), 5.16 dd, 1H, J 3.7 a 8.9 (O-C-H), 4.62 m, 2H (P-OCH), 4.13

dd, 1H, J 10.0 a 13.7 a 3.91 dd, 1H, J 8.6 a 13.7 (P-CH₂), 3.84 dd, 1H,

J 3.7 a 11.0 a 3.52 dd, 1H, J 8.9 a 11.0 (CH₂-Br), 1.26 d, 6H a 1.24 d, 6H,

J (CH₃, CH) 6.1 (CH₃).¹³C NMR: 88.10 d,J (P, C) 15.6 (O-C-S), 70.76 d

a 70.71 d, J (P, C) 6.8 (P-OC), 62.14 d, J (P, C) 166.0 (P-C), 34.62 (C-Br),

24.03 d a 24.00 d a 23.92 d a 23.89 d, J (P, C) 3.9 (CH₃).Arom C: 1341. 7,

2C, 130.42, 129.39, 2C, 128.74.

Diisopropyl 2-hydroxy-1-octylethoxymethanephosphonate (15)

The 3-chloroperoxybenzoic acid (0.807 g, 5.5 mmol) was added to a

solution of diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol)

1506

REJMAN ET AL.

and octanol (9 ml, 55 mmol) in dichloromethane (15 ml) at 0 ^ꢀC under argon

atmosphere, and the reaction mixture was kept at room temperature for

16 hours.The solution was washed with sodium hydrogencarbonate, organic

layer dried with anhydrous sodium sulfate, and evaporated.Chromato-

graphy on a silica gel column in 0750% of acetone in toluene aorded 0.95 g

(51.6%) of compound 15.

MS (FAB): 369.2 (MH ).¹H NMR (DMSO-d₆): 4.76 (1H, t, J_{OH, CH}

2

6.0, OH), 4.60 (2H, m, P-PCH), 4.52 (1H, t, J 5.4, O-CH-O), 3.77 (1H,

dd, J_P,CH 9.0, J_g 13.7, P-CH₂), 3.72 (1H, dd, J_P,CH 9.5, J_g 13.7, P-

CH₂), 3.70-3.58 (1H, m, O-CH₂), 3.44-3.31 (3H, m, O-CH₂), 1.50 (2H, m, C-

CH₂) 1.35-1.20 (10H, m, C-CH₂), 1.22 (12H, d, J_{CH CH}

(3H, t, J_CH,_CH

(d, P-OC), 70.34 (d, J_P,C 5.8, P-OC), 66.62 (O-C), 61.39 (O-C), 59.09 (d,

J_P,C 168.0, P-C), 31.39 and 29.41 and 28.95 and 28.86 and 25.78 and 22.24

(C-C), 23.94 (d, CH₃) 23.85 (d, J_P,C 4.9, CH₃), 14.09 (CH₃).

,

6.1, CH₃), 0.85

3

7.1, CH₃).¹³C NMR: 103.40 (d, J_P,C 11.7, O-C-O), 70.35

3

2

Diisopropyl 1-(3-chlorobenzoyloxy)-2-hydroxyethoxymethanephosphonate (16)

The 3-chloroperoxybenzoic acid (0.173 g, 1 mmol) was added under

argon atmosphere to a solution of diisopropyl vinyloxymethanephosphonate

(6) (0.22 ml, 1 mmol) in dichloromethane (5 ml) at 0 ^ꢀC, and the reaction was

kept aside at room temperature for 16 hrs.The solution was washed with

sodium hydrogencarbonate, dried with anhydrous sodium sulfate, and eva-

porated.Chromatography on a silica gel column in 0 750% of acetone in

toluene aorded 0.090 g (25%) of compound 16.

¹H NMR (DMSO-d₆): 8.00 (1H, dd, J 1.7,) 2.2 (1H, ddd, J 1.0 and 1.7

and 7.8 and 7.77, arom H), 7.97 (1H, ddd, J 1.0 and 2.2 and 8.0, arom H), 7.60

(1H, t, J 7.9, arom H), 5.99 (1H, dd, J₁ 4.6, J₂ 5.6, O-CH-O),5.17 (1H, t,

J_{OH, CH} 6.1, H), 4.60 (2H, m, P-OCH), 4.01 (2H, d, J_P,CH 9.0, P-CH₂), 3.65

2

(1H, ddd, J₁ 4.6, J₂ 6.1, J₃ 12.0, O-CH₂), 3.58 (1H, dt, J₁ 5.9, J₂ 5.9,

J₃ 12.0, O-CH₂), 1.23 (3H, d, CH₃), 1.22 (6H, d, CH₃), 1.21 (3H, d,

J_CH,_CH

6.1, CH₃).¹³C NMR: 99.52 (d, J_P,C 11.7, O-C-O), 70.68 (d, P-OC),

3

70.66 (d, J_{P, C} 6.8, P-OC), 63.13 (d, J_P,C 166.0, P-C), 61.48 (O-C), 23.94 (d,

CH₃), 23.92 (d, CH₃), 23.78 (2C, d, J_P,C 3.9, CH₃), arom: 164.59 (CO),

133.69 and 133.67 and 131.67 and 131.01 and 129.28 and 128.44.

9-N-(2-(1-adamantanyloxy)-2-phosphonomethoxyethyl)adenine (17a)

Synthon 8 (R1-adamantanyl; Badenine) was prepared by Method A

using N-iodosuccinimide (1.24 g, 5.5 mmol), 1-adamantanol (0.91 g, 6 mmol)

and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction

performed according to Method B with adenine (0.68 g, 5 mmol) followed by

deprotection and puri®cation (Method C ) aorded 318 mg (15%) of 17a.

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1507

Anal.calcd.for C ₁₈H₂₄N₅O₅PNa₂Á l2H₂O (503.41): C, 42.9, H, 5.6, N,

13.9, P, 6.2. Found: C, 43.0, H, 5.44, N, 13.52, P, 6.4. MS (FAB): 446.5

((M )Na).¹H NMR (D₂O): 8.22 and 8.18 (261H, s, H-2 and H-8), 5.24

(1H, dd, J_{2 ,1 a} 3.4, J_{2 ,1 b} 7.3, H-2⁰), 4.45 (1H, dd, J_{1 a,2} 3.4, J_gem 14.2,

0

H-1⁰a), 4.28 (1H, dd, J_{1 b,2} 7.3, J_gem 14.2, H-1⁰b), 3.80 (, 1H, dd

J_P,Cha 9.5, J_gem 12.7, P-CHa), 3.68 (, 1H, dd J_P,CHb 10.0, J_gem 12.7, P-

CHb), 2.10 (3H, m, C-CH adamantane), 1.56 (6H, m, C-CH adamantane),

1.46 (6H, m, C-CH adamantane).

0

9-N-(2-(2-azidoethoxy)-2-phosphonomethoxyethyl)adenine (17b)

Synthon 8 (R2-azidoethyl; Badenine) was prepared by Method A

using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-azidoethanol (1.3 g, 10 mmol)

and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reac-

tion performed according to Method B with adenine (1.35 g, 10 mmol) fol-

lowed by deprotection and puri®cation (Method C ) aorded 707 mg (20%)

of 17b.

HR FAB calcd for C₁₀H₁₅N₈O₅P 358.090304, found 381.080074

(M+Na).¹H NMR (D₂O): 8.17 and 8.16 (261H, s, H-8, H-2), 5.06 (1H, dd,

CH-2⁰, J_{2 1 a} 3.9, J_{2 1 b} 5.4), 4.47 (1H, dd, CH2-1⁰, J_{1 a2} 3.9, J_g 14.65),

0

4.41 (1H, dd, CH₂-1⁰, J_{1 b2} 5.6, J_g 14.65), 3.94 (1H, ddd, OCH₂, J₁ 3.7,

J₂ 5.6, J₃ 11.0), 3.67 (1H, ddd, OCH₂, J₁ 4.1, J₂ 6.1, J₃ 11.5), 3.89

(1H, dd, P-CH₂, J_PCHa 9.3, J_g 12.9), 3.76 (1H, dd, P-CH₂, J_PCHb 10.0,

J_g 12.9), 3.35 (2H, m, NCH₂),¹³C NMR: 154.90 (C-6), 151.875 (C-2),

148.73 (C-4), 142.78 (C-8), 117.61 (C-5), 101.33 (C-2⁰, d, J 11.7), 66.88

(OCH₂), 63.39 (PC, d, J 157.2), 50.23 (NCH₂), 45.09 (C-1⁰).

0

9-N-(Benzyloxy-2-phosphonomethoxyethyl)adenine (17c)

Synthon 8 (R-benzyl; B-adenine) was prepared by Method A using

N-iodosuccinimide (0.79 g, 3.5 mmol), benzoylalcohol (0.38 g, 3.5 mmol)

and diisopropyl vinyloxymethanephosphonate (6) (0.75 ml, 3.4 mmol).

Reaction performed according to Method B with adenine (0.47 g, 3.5 mmol)

followed by deprotection and puri®cation (Method C ) aorded 300 mg

(23%) of 17c.

Anal.calcd.for C ₁₅H₁₇N₅O₅PNa Á 3H₂O (455.35): C, 39.6, H, 5.1, N,

15.4, P, 6.8. Found: C, 39.34, H, 5.15, N, 15.26, P, 6.76. MS (FAB): 379.3

(MH ).¹H NMR (D₂O): 7.91 and 7.85 (261H, s, H-2 a H-8), 7.08 (1H, t,

arom H), 6.99 (2H, t, arom H), 6.81 (2H, d, arom H), 5.02 (1H, dd,

J_{2 ,1 a} 3.2, J_{2 ,1 b} 8.0, H-2⁰), 4.71 (1H, d, O-CH₂arom), 4.42 (1H, d,

0

J_gem 12.2, O-CH₂arom), 4.27 (1H, dd, J_{1 a,2} 3.2, J_g 14.7, H-1 a), 4.17

0

(1H, dd, J_{1 b,2} 8.0, J_g) 14.7, H-1 b), 3.93 (1H, dd, J_P,CHa 9.5, J_g 12.5,

P-CHa), 3.79 (1H, dd, J_P,CHb 10.0, J_g 12.5, P-CHb).

1508

REJMAN ET AL.

9-N-(2-tert-butyloxy-2-phosphonomethoxyethyl)adenine (17d)

Synthon 8 (Rtert-butyl; Badenine) was prepared by Method A using

N-iodosuccinimide (1.24 g, 5.5 mmol), tert-butanol (1.5 g, 20 mmol) and dii-

sopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction per-

formed according to Method B with adenine (0.68 g, 5 mmol) followed by

deprotection and puri®cation (Method C ) aorded 287 mg (16%) of 17d.

Anal.calcd.for C ₁₂H₁₉N₅O₅PNa Á 3H₂O (421.32): C, 34.2, H, 6.0, N,

16.6, P 7.4. Found: C, 34.56, H, 5.89, N, 16.6,P, 7.27.¹H NMR (D₂O): 8.21

0

and 8.17 (261H, s, H-2 and H-8), 5.11 (1H, dd, J_{2 ,1 a} 3.7, J_{2 ,1 b} 6.4, H-

2⁰), 4.45 (1H, dd, J_{1 a,2} 3.7, J_gem 14.7, H-1⁰b), 4.28 (1H, dd, J_{1 b,2} 6.4,

J_gem 14.7, H-1⁰b), 3.79 (1H, dd, J_P,CHa 9.8, J_gem 12.7, P-CHa), 3.70 (1H,

dd, J_P,CHb 10.2, J_gem 12.7, P-CHb).

0

9-N-(2-cyclohexyloxy-2-phosphonomethoxyethyl)adenine (17e)

Synthon 8 (Rcyclohexyl; Badenine) was prepared by Method A using

N-iodosuccinimide (1.24 g, 5.5 mmol), cyclohexanol (2.5 g, 25 mmol) and

diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction

performed according to Method B with adenine (0.68 g, 5 mmol) followed by

deprotection and puri®cation (Method C ) aorded 342 mg (18%) of 17e.

Anal.calcd.for C₁₄H₂₁N₅O₅PNa.3H ₂O (447.36): C, 37.6, H, 6.1, N, 15.7,

P, 6.9. Found: C, 37.83, H, 5.97, N, 15.93, P, 6.86. MS (FAB): 372.1 (MH ).1

0

H NMR (D₂O): 8.18 and 8.16 (261H, s, H-2 a H-8), 5.08 (1H, dd, J_{2 ,1 a} 3.7,

J_{2 ,1 b} 6.1, H-2⁰), 4.44 (1H, dd,J_{1 a,2} 3.7, J_gem 14.7, H-1⁰a), 4.30 (1H, dd,

0

J_{1 b,2} 6.1, J_gem 14.7, H-1⁰b), 3.85 (1H, dd,J_P,CHa 9.3, J_gem 12.7, P-

CHa), 3.67 (1H, dd, J_P,CHb 10.2, J_gem 12.7, P-CHb), 3.56 (1H, m, 1⁰⁰-CH),

1.90 (1H, m, C-CH), 1.60 (1H, m, C-CH), 1.40 (1H, m, C-CH), 1.30 (2H, m,

C-CH), 1.23 (, 1H, m C-CH), 1.05 (2H, m, C-CH), 0.82 (1H, m, C-CH).

0

9-N-(2-(2-¯uoroethoxy)-2-phosphonomethoxyethyl)adenine (17f)

Synthon 8 (R2-¯uoroethyl, Badenine) was prepared by Method A

using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-¯uoroethanol (0.6 ml, 10 mmol)

and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction

performed according to Method B with adenine (0.68 g, 5 mmol) followed by

deprotection and puri®cation (Method C ) aorded 114 mg (7%) of 17f.

Anal.calcd.for C ₁₀H₁₄N₅O₅PFNa Á 4H₂O (429.27): C, 28.0, H, 5.2, N,

16.3, P, 7.2. Found: C, 28.03, H, 5.17, N, 16.27, P, 8.05.¹H NMR (D₂O): 8.22

0

and 8.21 (261H, s, H-2 and H-8), 5.07 (1H, dd, J_{2 ,1 a} 3.9, J_{2 ,1 b} 5.4, H-

2⁰), 4.54 (1H, dddd, J_{1 a,2 a} 2.2, J_{1 a,2 b} 6.1, J_gem 11.0, J_{1 a, F} 21.5, H-

00

1⁰⁰a), 4.50 (1H, dd, J_{1 a,2} 3.9, J_gem 14.7, H-1a), 4.44 (1H, dddd, J_{1 b,}

0

00

5.4, J_{1 b,2 b} 2.2, J_gem 11.0, J_{1 b,F} 20.5, H-1⁰⁰b), 4.43 (1H, dd, J_{1 b,}

00

0

2 a

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1509

5.4, J_gem 14.7, H-1⁰b), 4.02 (1H, dddd, J_{2 a,1 a} 2.2, J_{2 a,1 b} 5.4,

00

2⁰

J_gem 12.5, J_{2 a,F} 32.5, H-2⁰⁰a), 3.82 (1H, dddd, J_{2 b,1 a} 6.1, J_{2 b,1 b} 2.2,

00

J_gem 12.5, J_{2 b,F} 30.3, H-2⁰⁰b), 3.83 (1H, dd, J_P,CHa 9.5, J_gem 12.7,

00

P-CHa), 3.67 (1H, dd, J_P,CHb 10.0, J_gem 12.7, P-CHb).

9-N-(2-(8-hydroxy-3,6-dioxaoctyloxy)-2-phosphonomethoxyethyl)

adenine (17g)

Synthon 8 (R8-dimethoxytrityloxy-3,6-dioxaoctyl; Badenine) was

prepared by Method A using N-iodosuccinimide (2.48 g, 11 mmol), 8-dime-

thoxytrityloxy-3,6-dioxaoctanol (8.8 g, 20 mmol) and diisopropyl vinyloxy-

methanephosphonate (6) (2.2 ml, 10 mmol). Reaction performed according to

Method B with adenine (1.35 g, 10 mmol) followed by deprotection and pur-

i®cation (Method C ) aorded 139 mg (3.3%) of 17g.

Anal.calcd.for C ₁₄H₂₃N₅O₈PNa.2H₂O (479.37): C, 35.1, H, 5.7, N,

14.6. Found: C, 35.08, H, 5.72, N, 14.48. MS (FAB): 422.4 (MH ).¹H NMR

0

(D₂O): 8.215 and 8.21 (261H s, H-2 and H-8), 5.05 (1H, dd, J_{2 ,1 a} 3.9,

J_{2 ,1 b} 5.6, H-2⁰), 4.48 (1H, dd, J_{1 a, 2} 3.9, J_gem 14.7, H-1⁰a), 4.42 (1H, dd,

0

J_{1 b,2} 5.6, J_gem 14.7, H-1⁰b), 3.93 (1H, m, OCH₂), 3.71 (1H, m, OCH₂),

3.87 (1H, dd, J_P,CHa 9.3, J_gem 12.9, P-CHa), 3.75 (1H, dd, J_P,CHb 9.8,

J_gem 12.9, P-CHb), 3.69 (2H, m, (OCH₂), 3.5773.40 (8H, m, (OCH₂).

0

9-N-(2-(2-hydroxyethoxy)-2-phosphonomethoxyethyl)adenine (17h)

Synthon 8 (R2-benzoyloxyethyl; Badenine) was prepared by Method

A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-benzoyloxyethanol (1.7 g,

10 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol).

Reaction performed according to Method B with adenine (0.68 g, 5 mmol)

followed by deprotection and puri®cation (Method D) aorded 160 mg (9%)

of 17h.

Anal.calcd.for C ₁₀H₁₄N₅O₆PNa₂Á3H₂O (431.26): C, 27.9, H, 4.7, N,

16.2, P 7.2. Found: C, 27.68, H, 4.3, N, 15.58, P, 7.8. MS (FAB): 334.1

(MH ).¹H NMR (D₂O): 8.21 and 8.20 (261H, s, H-2 and H-8), 5.04 (1H, t,

J 4.6, H-2⁰), 4.47 (1H, dd, J_{1 a,2} 4.4, J_gem 14.7, H-1⁰a), 4.43 (1H, dd, J_{1 b,}

0

4.9, J_gem 14.7, H-1⁰b), 3.87 (2H, m, O-CH₂), 3.84 (1H, dd, J_P,CHa 9.3,

2⁰

J_gem 12.9, P-CHa), 3.68 (1H, dd, J_P,CHb) 9.8, J_gem 12.9, P-CHb), 3.64

(2H, m, O-CH₂).

9-N-(2-methoxy-2-phosphonomethoxyethyl)adenine (17i)

Synthon 8 (Rmethyl; Badenine) was prepared by Method A using

N-iodosuccinimide (0.52 g, 2.3 mmol), methanol (0.1 ml, 2.52 mmol) and

diisopropyl vinyloxymethanephosphonate (6) (0.51 ml, 2.3 mmol). Reaction

1510

REJMAN ET AL.

performed according to Method B with adenine (0.31 g, 2.3 mmol) followed

by deprotection and puri®cation (Method C ) aorded 340 mg (48%) of 17i.

Anal.calcd.for C H₁₂N₅O₅PNa₂Á3H₂O (401.22): C, 26.9, H, 4.5, N, 17.5,

9

P, 7.7. Found: C, 27.24, H, 4.31, N, 17.40, P, 7.67. MS (FAB): 303.2 (M ).¹H

0

NMR (D₂O): 8.13 and 8.05 (261H, s, H-2 and H-8), 4.95 (1H, dd, J_{2 , 1 a} 4.4,

0

J_{2 , 1 b} 4.9, H-2⁰), 4.40 (1H, dd, J_{1 a, 2} 4.4, J_g 14.6, H - 1 a), 4.36 (1H, dd,

0

J_{1 b, 2}4.9, J_gem 14.6, H -1⁰b), 3.88 (1H, dd, J_{P, CHa} 9.5, J_gem 12.5, P - Cha),

₀0

0

3.73 (1H, dd, J_{P, CHb} 9.8, J_gem 12.5, P - Chb), 3.5 (3H, s, OCH₃).

9-N-(2-octyloxy-2-phosphonomethoxyethyl)adenine (17j)

Synthon 8 (Rn-octyl; Badenine) was prepared by Method A using

N-iodosuccinimide (1.24 g, 5.5 mmol), n-octanol (0.72 g, 5.5 mmol) and di-

isopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction per-

formed according to Method B with adenine (0.68 g, 5 mmol) followed by

deprotection and puri®cation (Method C ) aorded 466 mg (23%) of 17j.

HR FAB calcd.for C ₁₆H₂₈N₅O₅P 401.182807, found 402.190633

(MH).¹H NMR (D₂O): 8.23 and 8.205 (261H, s, H-8, H-2), 5.03 (1H, dd,

CH-2⁰, J_{2 1 a} 3.4, J_{2 1 b} 7.1), 4.50(1H, dd, CH₂-1⁰, J_{1 a2} 3.4, J_g 14.7), 4.36

0

(1H, dd, CH₂-1⁰, J_{1 b2} 7.1, J_g 14.7), 3.83 (1H, dd, P-CH₂, J_PCHa 9.1,

J_g 12.7), 3.68 (1H, dd, P-CH₂, J_PCHb 9.8, J_g 12.7), 3.78 (1H, m, OCH₂),

3.43 (1H, m, OCH₂),1.18-1.32 (4H, m, CCH₂), 0.65-1.10 (11H, m, CCH₂).

0

9-N-(bis-2,2-(phosphonomethoxy)ethyl)adenine (17k)

Synthon 8 (Rdiisopropylphosphonomethyl; Badenine) was prepared

by Method A using N-iodosuccinimide (0.79 g, 3.5 mmol), diisopropyl

hydroxymethanephosphonate (51) (0.62 g, 3.16 mmol) and of diisopropyl

vinyloxymethanephosphonate (6) (0.75 ml, 3.4 mmol). Reaction performed

according to Method B with adenine (0.47 g, 3.5 mmol) followed by depro-

tection and puri®cation (Method C ) aorded 160 mg (23%) of 17k.

Anal.calcd.for C H₁₃N₅O₈P₂Na₂Á5=2H₂O (472.21): C, 21.3, H, 4.4, N,

9

13.8, P, 12.2. Found: C, 21.48, H, 4.25, N, 13.61, P, 11.67. MS (FAB): 383.2

0

(MH ).¹H NMR (D₂O): 8.16 and 8.06 (261H, s, H-2 a H-8), 5.02 (1H, t, J_{2 ,}

0

1⁰

4.6, H-2 ), 4.41 (2H, d, J_{1 ,2} 4.6, H-1 ), 3.86 (2H, dd, J_P,CHa 9.5,

J_g 12.9, P-CHa), 3.71 (2H, dd, J_P, CHb 9.8, J_g 12.9, P-CHb).

9-N-(2-(2,2,2-tri¯uoroethoxy)-2-phosphonomethoxyethyl)adenine (17l)

Synthon 8 (R2,2,2-tri¯uoroethyl; Badenine) was prepared by

Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2,2,2-tri¯uoroethanol

(0.55 g, 5.5 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml,

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1511

5 mmol).Reaction performed according to Method B with adenine (0.68 g,

5 mmol) followed by deprotection and puri®cation (Method C ) aorded

367 mg (20 ) of 17l.

Anal.calcd.for C ₁₀H₁₃N₅O₅PF₃NaÁ3H₂O (448.25): C, 26, H, 4.1, N,

15.7, P, 6.9. Found: C, 26.58, H, 3.98, N, 15.15, P, 7.13. MS (FAB): 372

0

(MH ).¹H NMR (D₂O): 8.17 (2H, s, H-2 a H-8), 5.15 (dd, 1H, J_{2 ,1 a} 3.9,

0

J_{2 ,1 b} 4.6, H-2⁰), 4.50 (dd, 1H, J_{1 a,2} 3.9, J_gem 14.9, H-1⁰), 4.45 (dd, 1H,

0

J_{1 b,2} 4.6, J_gem 14.9, H-1⁰), 4.26 (dq, 1H, J_{1 a,F} 8.8, J_gem 12.5, H-1⁰⁰),

0

00

4.12 (dq, 1H, J_{1 b,F} 8.8, J_gem 12.5, H-1⁰⁰, 3.87 (dd, 1H, J_{P, CHa} 9.5,

00

J_gem 12.7, P-CHa), 3.74 (dd, 1H, J_P,CHb 10.0, J_gem 12.7, P-CHb).

1-N-(2-allyloxy-2-phosphonomethoxyethyl)cytosine (18a)

Synthon 8 (Rallyl; Bcytosine) was prepared by Method A using

N-iodosuccinimide (1.24 g, 5.5 mmol), allyl alcohol (0.58 g, 10 mmol) and

diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction

performed according to Method B with cytosine (0.56 g, 5 mmol) followed by

deprotection and puri®cation (Method C ) aorded 564 mg (37%) of 18a.HR

FAB calcd for C₁₀H₁₆N₃O₆P 305.077673, found 350.049388 (M-H2Na).¹H

NMR (D₂O): 7.60 (1H, d, H-6), 5.99 (1H, d, H-5, J₅₆ 7.3), 5.86 (1H, ddt, 5⁰-

H, J_{5 4} 5.9, J_{5 6 a(trans)} 17.1, J_{5 6 b(cis)} 10.5), 5.29 (1H, dq, 6⁰-H,

0

0 0

0

J_{6 4}ꢁ J_g 1.5, J_{6 a5} 17.1), 5.22 (1H, dq, 6 -H, J_{6 4}ꢁ J_g 1.5, J_{6 b5} 10.5),

4.91 (1H, dd, CH-2⁰, J_{2 1 a} 4.4, J_{2 1 b} 5.9), 4.30 (1H, ddt, 4⁰-H, J_{4 a6} 1.5,

0

J_{4 a5} 5.6, J_g 12.7), 4.12 (1H, ddt, 4 -H, J_{4 b6} 1.5, J_{4 b5} 6.3, J_g 12.7),

0

4.06 (1H, dd, CH₂-1⁰, J_{1 a2} 4.4, J_g 14.1), 3.85 (1H, dd, CH₂-1 , J_{1 b2} 6.1,

J_g 14.1), 3.82 (1H, dd, P-CH₂, J_PCHa 9.5, J_g 12.7), 3.64 (1H, dd, P-CH₂,

J_PCHb 10.0, J_g 12.7),¹³C NMR: 166.21 (C-4), 158.00 (C-2), 147.67 (C-6),

133.05 (C-5⁰), 118.27 (C-6⁰), 100.80 (C-2⁰,d , J 11.7), 95.26 (C-5), 69.60 (C-

4⁰), 63.73 (P-C, d, J 157.2), 51.315 (C-1⁰).

0

1-N-(2-(2-¯uoroethoxy)-2-phosphonomethoxyethyl)cytosine (18b)

Synthon 8 (R2-¯uoroethyl; Bcytosine) was prepared by Method A

using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-¯uoroethanol (0.6 ml,

10 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol).

Reaction performed according to Method B with 2,6-diaminopurine (0.75 g,

5 mmol) followed by deprotection and puri®cation (Method C) aorded

451 mg (29%) of 18b.

HR FAB calcd.for C ₉H₁₅FN₃O₆P 311.068252, found 312.076077

(MH).¹H NMR (D₂O): 7.66 (1H, d, H-6), 6.03 (1H, d, H-5, J₅₆ 7.3), 4.94

(1H, dd, CH-2⁰, J_{2 1 a} 4.6, J_{2 1 b} 5.6), 4.61 (1H, dddd, FCH₂, J_{5 a4 a} 2.7,

0

J_{5 a4 b} 5.7, J_5'aF 47.6, J_g 11), 4.57 (1H, dddd, FCH₂, J_{5 b4 a} 4.9,

J_{5 b4 a} 2.7, J_{5 aF} 47.4, J_g 11), 4.06 (1H, dd, CH₂-1⁰, J_{1 a2} 4.6, J_g 14.2),

0

1512

REJMAN ET AL.

3.94 (1H, dd, CH₂-1⁰, J_{1 b2} 5.6, J_g 14.2), 4.05 (1H, dddd, OCH₂,

0

J_{4 a5 a} 2.7, J_{4 a5 b} 4.9, J_{4 aF} 32.8, J_g 12.4), 3.89 (1H, dddd, OCH₂,

0

J_{4 b5 a} 2.7, J_{4 b5 b} 5.7, J_{4 bF} 30.5, J_g 12.4), 3.84 (1H, dd, P-CH₂,

J_PCHa 9.5, J_g 12.9), 3.67 (1H, dd, P-CH₂, J_PCHb 10.0, J_g 12.9),¹³C

NMR: 164.95 (C-4), 156.35 (C-2), 148.07 (C-6), 101.48 (C-2⁰,d, J 12.7), 83.21

(C-F, d, J 164.1), 67.575 (O-C, d , J 17.6), 63.31 (P-C, d, J 158.2), 50.85

(C-1⁰).

1-N-(2-methoxy-2-phosphonomethoxyethyl)cytosine (18c)

Synthon 8 (Rmethyl; Bcytosine) was prepared by Method A using

N-iodosuccinimide (1.24 g, 5.5 mmol), methanol (0.81 ml, 20 mmol) and

diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol). Reaction

performed according to Method B with cytosine (0.56 g, 5 mmol) followed

by deprotection and puri®cation (Method C ) aorded 741 mg (53%) of

18c.

HR FAB calcd for C₈H₁₄N₃O₆P 279.06203, found 302.051794

(MNa).¹H NMR (D₂O): 7.63 (1H, d, H-6, J₅₆ 7.3), 6.01 (1H, d, H-5),

4.79 (1H, brt, CH-2⁰, J_{2 1 a} 4.9, J_{2 1 b} 5.1), 4.00 (1H, dd, CH₂-1⁰,

0

0 0

0

J_{1 a2} 4.9, J_g 14.2), 3.99 (1H, dd, CH₂-1 , J_{1 b2} 5.1, J_g 14.2), 3.82 (1H,

dd, P-CH₂, J_PCHa 9.5, J_g 12.9), 3.66 (1H, dd, P-CH₂, J_PCHb 10.0,

J_g 12.9), 3.47 (3H, s, OCH₃),¹³C NMR: 165.32 (C-4), 156.89 (C-2), 147.85

(C-6), 102.12 (C-2⁰,d, J 11.7), 95.15 (C-5), 63.47 (P-C, d, J 158.2), 54.98

(OCH₃).

2,6-diamino-9-N-(2-(2-azidoethoxy)-2-phosphonomethoxyethyl)purine (19a)

Synthon 8 (R2-azidoethyl; B2,6-diaminopurine) was prepared by

Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-azidoethanol (1.3 g,

15 mmol) and diisopropyl vinyloxymethanephosphonate (6) (2.2 ml,

10 mmol).Reaction performed according to Method B with 2,6-diamino-

purine (1.5 g, 10 mmol) followed by deprotection and puri®cation (Method C )

aorded 747 mg (20%) of 19a.

HR FAB calcd for C₁₀H₁₆N₉O₅P 373.101203, found 418.072918 (M-

H2Na).¹H NMR (D₂O): 7.885 (1H, s, H-8), 5.02 (1H, dd, CH-2⁰,

J_{2 1 a} 3.7, J_{2 1 b} 5.9), 4.32 (1H, dd, CH₂-1⁰, J_{1 a2} 3.7, J_g 14.65), 4.24

0

(1H, dd, CH₂-1⁰, J_{1 b2} 5.9, J_g 14.65), 3.95 (1H, ddd, OCH₂, J₁ 3.7,

J₂ 5.6, J₃ 11.0), 3.65 (1H, ddd, OCH₂, J₁ 3.7, J₂ 6.1, J₃ 11.0), 3.81

(1H, dd, P-CH₂, J_PCHa 9.3, J_g 12.2), 3.67 (1H, dd, P-CH₂,

J_PCHb 10.0, J_g 12.2), 3.34 (2H, m, NCH₂),¹³C NMR: 159.43 (C-2),

155.57 (C-6), 150.94 (C-4), 140.46 (C-8), 112.24 (C-5), 101.57 (C-2⁰,d,

J 11.7), 66.915 (OCH₂), 64.17 (PC, d, J 155.3), 50.31 (NCH₂, d,

J 163.6), 44.87 (C-1⁰).

0

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1513

2,6-diamino-9-N-(2-(2-benzoyloxyethoxy)-2-phosphonomethoxyethyl)-

purine (19b)

Synthon 8 (R2-benzoyloxyethyl; B2,6-diaminopurine) was prepared

by Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-benzoylox-

yethanol (1.7 g, 10 mmol) and diisopropyl vinyloxymethanephosphonate (6)

(1.1 ml, 5 mmol). Reaction performed according to Method B with 2,6-dia-

minopurine (0.75 g, 5 mmol) followed by deprotection and puri®cation

(Method C ) aorded 178 mg (8%) of 19b.

HR FAB calcd for C₁₇H₂₁N₆O₇P 452.120935, found 475.110705

(MNa).¹H NMR (D₂O): 7.79 (1H, s, H-8), 7.64 (3H, m, arom.), 7.44 (2H, t,

arom.), 5.10 (1H, dd, CH-2⁰, J_{2 1 a} 2.7, J_{2 1 b} 8.3), 4.3474.29 (2H, m, CH₂-

1⁰), 4.23 (1H, m, 4⁰-O-CH₂), 4.1374.06 (3H, m, 4⁰-O-CH₂), 3.81 (1H, dd, P-

CH₂, J_PCHa 9.5, J_g 12.0), 3.69 (1H, dd, P-CH₂, J_PCHb 10.0,

J_g 12.0),¹³C NMR: 165.9 (arom.), 159.14 (C-2), 154.97 (C-6), 150.31 (C-4),

140.04 (C-8), 133.385 (arom.), 128.53 (arom.), 128.165 (arom.), 127.69

(arom.), 112.02 (C-5), 102.40 (C-2⁰,d, J 11.7), 66.88 (O-C), 65.05 (O-C),

65.06 (P-C, d, J 152.0), 44.97 (C-1⁰).

0

0 0

2,6-diamino-9-N-(2-(2-¯uoroethoxy)-2-phosphonomethoxyethyl)purine (19c)

Synthon 8 (R2-¯uoroethyl; B2,6-diaminopurine) was prepared by

Method A using N-iodosuccinimide (2.25 g, 10 mmol), 2-¯uoroethanol (1.1 ml,

18 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.98 ml,

9 mmol).Reaction performed according to Method B with 2,6-diaminopurine

(1.35 g, 9 mmol) followed by deprotection and puri®cation (Method C )

aorded 338 mg (11%) of 19c.

MS (FAB): 351.1 (MH ).¹H NMR (D₂O): 7.91 (1H, s, H-8), 5.01 (1H,

dd, CH-2⁰, J_{2 1 a} 3.4, J_{2 1 b} 6.3), 4.49 (1H, dddd, J_{5 a4 a} 2.0, J_{5 a4}b 6.1,

0

J_{5 aF} 47.6, J_g 10.7), 4.44 (1H, dddd, J_{5 b4 a} 5.4, J_{5 b4 a} 2.0, J_{5 aF} 47.6,

0

J_g 10.7), 4.35 (1H, dd, CH₂-1⁰, J_{1 a2} 3.4, J_g 14.65), 4.24 (1H, dd, CH₂-1 ,

0

J_{1 b2} 6.3, J_g 14.65), 4.03 (1H, dddd, J_{4 a5 a} 2.0, J_{4 a5 b} 5.6, J_{4 aF} 32.2,

0

J_g 12.4), 3.76 (1H, dddd, J_{4 b5 a} 6.1, J_{4 b5 b} 2.0, J_{4 bF} 30.8, J_g 12.4),

3.73 (1H, dd, P-CH₂, J_PCHa 9.0, J_g 12.2), 3.54 (1H, dd, P-CH₂,

J_PCHb 9.8, J_g 12.2),¹³C NMR: 159.76 (C-2), 155.83 (C-6), 151.145 (C-4),

140.67 (C-8), 112.32 (C-5), 101.71 (C-2⁰,d, J 11.7), 83.14 (C-F, d, J 163.6),

67.41 (O-C,d, J 18.6), 65.59 (P-C, d, J 151.4), 44.95 (C-1⁰).

2,6-diamino-9-N-(2-(2-hydroxyethoxy)-2-phosphonomethoxyethyl)purine (19d)

Synthon 8 (R2-benzoyloxyethyl; B2,6-diaminopurine) was prepared

by Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-benzoylox-

yethanol (1.7 g, 10 mmol) and diisopropyl vinyloxymethanephosphonate (6)

1514

REJMAN ET AL.

(1.1 ml, 5 mmol). Reaction performed according to Method B with 2,6-dia-

minopurine (0.75 g, 5 mmol) followed by deprotection and puri®cation

(Method D) aorded 87 mg (5%) of 19d.

HR FAB calcd.for C ₁₀H₁₇N₆O₆P 348.094720, found 393.066435 (M-

1

H2Na). H NMR (D₂O): 7.93 (1H, s, H-8), 4.98 (1H, dd, CH-2⁰, J_{2 1 a} 3.9,

0

J_{2 1 b} 5.6), 4.33 (1H, dd, CH₂-1⁰, J_{1 a2} 3.9, J_g 14.6), 4.25 (1H, dd, CH₂-

0

1⁰, J_{1 b2} 5.6, J_g 14.6), 3.86 (1H, m, OCH₂), 3.74 (1H, dd, P-CH₂,

J_PCHa 9.3, J_g 12.4), 3.62 (3H, m, OCH₂), 3.57 (1H, dd, P-CH₂,

J_PCHa 9.6, J_g 12.4),¹³C NMR: 159.71 (C-2), 155.82 (C-6), 151.06 (C-4),

140.76 (C-8), 112.32 (C-5), 101.59 (C-2⁰,d, J 11.7), 69.30 (OCH₂), 64.96 (P-

C, d, J 151.4), 60.36 (OCH₂), 45.08 (C-1⁰).

0

2-amino-6-bromo-9-N-(2-allyloxy-2-phosphonomethoxyethyl)purine (20a)

Synthon 8 (Rallyl; B2-amino-6-chloropurine) was prepared by

Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), allyl alcohol (0.58 g,

10 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol).

Reaction performed according to Method B with 2-amino-6-chloropurine

(0.75 g, 5 mmol) followed by deprotection and puri®cation (Method C )

aorded 389 mg (21%) of 20a.

FAB 453 (M-H2Na).¹H NMR (D₂O): 8.18 (1H, s, H-8), 5.68 (1H,

brddt, 5⁰-CH, J_{5 4 a}ꢁ J_{5 4 b} 5.9, J_{5 6 a} 17.2, J_{5 6 b} 10.5), 5.12 (1H, dq, 6⁰-

0

0 0

0

CH₂, J_{6 a4}ꢁ J_g 1.5, J_{6 a5} 17.2), 5.07 (1H, dq, 6 -CH₂, J_{6 b4}ꢁ J_g 1.5,

0

0 0

J_{6 b5} 10.5), 5.01 (1H, dd, CH-2 , J_{2 1 a} 3.9, J_{2 1 b} 5.8), 4.39 (1H, dd, CH₂-

0

1⁰, J_{1 a2} 3.9, J_g 14.4), 4.30 (1H, dd, CH₂-1 , J_{1 b2} 5.8, J_g 14.4), 4.26

0

(1H, ddt, 4⁰-H, J_{4 a6} 1.5, J_{4 a5} 5.5, J_g 12.7), 4.04 (1H, ddt, 4 -H,

0

J_{4 b6} 1.5, J_{4 b5} 6.3, J_g 12.7), 3.83 (1H, dd, P-CH₂, J_PCHa 9.4,

J_g 12.8), 3.66 (1H, dd, P-CH₂, J_PCHb 9.8, J_g 12.8),¹³C NMR: 159.04 (C-

2), 152.14 (C-4), 144.95 (C-8), 142.12 (C-6), 132.84 (C-5⁰), 125.84 (C-5),

117.96 (C-6⁰), 100.65 (C-2⁰,d, J 12.2), 69.52 (C-4⁰), 64.05 (P-C, d,

J 156.25), 45.31 (C-1⁰).

2-amino-6-bromo-9-N-(2-(2-benzoyloxyethoxy)-

2-phosphonomethoxyethyl)purine (20b)

Synthon 8 (R2-benzoyloxyethyl; B2-amino-6-chloropurine) was

prepared by Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-ben-

zoyloxyethanol (1.7 g, 10 mmol) and diisopropyl vinyloxymethanepho-

sphonate (6) (1.1 ml, 5 mmol). Reaction performed according to Method B

with 2-amino-6-chloropurine (0.85 g, 5 mmol) followed by deprotection and

puri®cation (Method C ) aorded 147 mg (6%) of 20b.

FAB 562.2 (M2Na).¹H NMR (D₂O): 8.17 (1H, s, H-8), 7.88 (2H, d,

arom.), 7.56 (1H, t, arom.), 7.49 (2H, t, arom.), 5.08 (1H, t, CH-2⁰, J 5.3),

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1515

0

4.43 (1H, dd, CH₂-1⁰, J_{1 a2} 5.0, J_g 14.4), 4.33 (1H, dd, CH₂-1 , J_{1 a2} 5.5,

J_g 14.4), 4.23 (2H, m, 4⁰-O-CH₂), 4.12 (2H, m, 4⁰-O-CH₂), 3.82 (1H, dd, P-

CH₂, J_PCHa 9.3, J_g 12.0), 3.69 (1H, dd, P-CH₂, J_PCHb 10.0, J_g 12.0).

0

2-amino-6-bromo-9-N-(2-(2-¯uoroethoxy)-2-phosphonomethoxyethyl)-

purine (20c)

Synthon 8 (R2-¯uoroethyl; B2-amino-6-chloropurine) was prepared

by Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-¯uoroethanol

(0.6 ml, 10 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml,

5 mmol).Reaction performed according to Method B with 2-amino-6-chlor-

opurine (0.85 g, 5 mmol) followed by deprotection and puri®cation (Method

C ) aorded 747 mg (40%) of 20c.

1

H NMR (D₂O): 8.165 (1H, s, H-8), 5.05 (1H, dd, CH-2⁰. J_{2 1 a} 3.9,

0

J_{2 1 b} 5.4), 4.54 (1H, dddd, F-CH₂, J_{5 a4 a} 2.2, J_{5 a4 b} 5.9, J_{5 aF} 47.9,

0

J_g 11.0), 4.51 (1H, dddd, F-CH₂, J_{5 b4 a} 5.1, J_{5 b4 a} 2.4, J_{5 aF} 47.6,

J_g 11.0), 4.40 (1H, dd, CH₂-1⁰, J_{1 a2} 3.9, J_g 14.65), 4.33 (1H, dd, CH₂-1 ,

0

J_{1 b2} 5.4, J_g 14.65), 4.04 (1H, dddd, 4 -O-CH₂, J_{4 a5 a} 2.2, J_{4 a5 b} 5.1,

J_{4 aF} 32.7, J_g 12.4), 3.85 (1H, dddd, 4⁰-O-CH₂, J_{4 b5 a} 5.9, J_{4 b5 b} 2.4,

0

J_{4 bF} 30.0, J_g 12.4), 3.86 (1H, dd, P-CH₂, J_PCHa 9.3, J_g 12.9), 3.71

(1H,dd, P-CH₂, J_PCHb 10.0, J_g 12.9),¹³C NMR: 158.98 (C-2), 152.015 (C-

4), 144.83 (C-8), 141.99 (C-6), 125.68 (C-5), 101.22 (C-2⁰, d, J 11.7), 83.07

(C-F, d, J 163.1), 67.39 (O-C, d, J 18.6), 63.34 (P-C, d, J 157.2), 44.975

(C-1⁰).

9-N-(2-allyloxy-2-phosphonomethoxyethyl)guanine (21a)

Synthon 8 (Rallyl; B2-amino-6-chloropurine) was prepared by

Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), allyl alcohol (0.58 g,

15 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml, 5 mmol).

Reaction performed according to Method B with 2-amino-6-chloropurine

(0.85 g, 5 mmol) followed by deprotection and puri®cation (Method D)

aorded 158 mg (9%) of 21a.

HR FAB calcd.for C ₁₁H₁₆N₅O₆P 345.083821 found 368.073592

(MNa).¹H NMR (D₂O): 7.87 (1H, s, H-8), 5.69 (1H, dddd, 5⁰-CH,

J_{5 4 a} 5.5, J_{5 4 b} 6.4, J_{5 6 a} 17.2, J_{5 6 b} 10.4), 5.14 (1H, dq, 6⁰-CH₂,

0

0 0

0

J_{6 a4}ꢁ J_g 1.6, J_{6 a5} 17.2), 5.09 (1H, ddt, 6 -CH₂, J_{6 b4} 1.2, J_g 1.6,

0

0 0

0

J_{6 b5} 10.4), 5.00 (1H, dd, CH-2 , J_{2 1 a} 3.5, J_{2 1 b} 6.5), 4.33 (1H, dd, CH₂-

1⁰, J_{1 a2} 3.5, J_g 14.6), 4.22 (1H, dd, CH₂-1 , J_{1 b2} 6.5, J_g 14.6), 4.27

0

(1H, brddt, 4⁰-H, J_{4 a6} 1.2, J_{4 a5} 5.5, J_g 12.8), 4.03 (1H, ddt, 4 -H,

0

13

0

J_{4 b6} 1.2, J_{4 b5} 6.4, J_g 12.8). C NMR: 158.75 (C-6), 153.45 (C-2),

151.64 (C-4), 140.54 (C-8), 132.94 (C-5⁰), 117.83 (C-6⁰), 115.41 (C-5), 100.98

(C-2⁰, d, J 11.7), 69.56 (C-4⁰), 64.86 (P-C, d, J 154.8), 45.31 (C-1⁰).

1516

REJMAN ET AL.

9-N-(2-(2-¯uoroethoxy)-2-phosphonomethoxyethyl)guanine (21b)

Synthon 8 (R2-¯uoroethyl; B2-amino-6-chloropurine) was prepared

by Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-¯uoroethanol

(0.6 ml, 10 mmol) and diisopropyl vinyloxymethanephosphonate (6) (1.1 ml,

5 mmol).Reaction performed according to Method B with 2-amino-6-chlor-

opurine (0.85 g, 5 mmol) followed by deprotection and puri®cation (Method

D) aorded 405 mg (23%) of 21b.

HR FAB calcd.for C ₁₀C₁₅FN₅O₆P 351.074400, found 374.064170

1

(MNa). H NMR (D₂O): 7.86 (1H, s, H-8), 5.02 (1H, dd, CH-2⁰, J_{2 1 a} 4.0,

0

J_{2 1 b} 5.7), 4.54 (1H, dddd, J_{5 a4 a} 2.2, J_{5 a4 b} 6.0, J_{5 aF} 47.6, J_g 10.8),

0

4.50 (1H, dddd, J_{5 b4 b} 2.2, J_{5 b4 a} 5.4, J_{5 aF} 47.6, J_g 10.8), 4.32 (1H, dd,

CH₂-1⁰, J_{1 a2} 4.0, J_g 14.6), 4.24 (1H, dd, CH₂-1 , J_{1 b2} 5.7, J_g 14.6),

0

4.03 (1H, dddd, J_{4 a5 a} 2.2, J_{4 a5 b} 5.4, J_{4 aF} 32.2, J_g 12.4), 3.81 (1H,

0

dddd, J_{4 b5 a} 6.0, J_{4 b5 b} 2.2, J_{4 bF} 31.0, J_g 12.4), 3.81 (1H, dd, P-CH₂,

J_PCHa 9.4, J_g 12.7), 3.65 (1H, dd, CH₂-1⁰, J_PCHb 9.8, J_g 12.7),¹³C

NMR: 158.64 (C-6), 153.44 (C-2), 151.55 (C-4), 140.44 (C-8), 115.29 (C-5),

101.52 (C-2⁰, d, J 11.2), 83.15 (C-5⁰, d, J 163.6), 67.35 (C-4⁰, d, J 18.6),

63.97 (P-C, d, J 155.3), 44.93 (C-1⁰).

9-N-(2-(2-hydroxyethoxy)-2-phosphonomethoxyethyl)guanine (21c)

Synthon 8 (R2-benzoyloxyethyl; B2-amino-6-chloropurine) was

prepared by Method A using N-iodosuccinimide (1.24 g, 5.5 mmol), 2-ben-

zoyloxyethanol (1.7 g, 10 mmol) and diisopropyl vinyloxymethanepho-

sphonate (6) (1.1 ml, 5 mmol). Reaction performed according to Method B

with 2-amino-6-chloropurine (0.85 g, 5 mmol) followed by deprotection and

puri®cation (Method D) aorded 35 mg (2%) of 21c.

HR FAB calcd.for C ₁₀H₁₆N₅O₇P 349.078736, found 372.068506

1

(MNa). H NMR (D₂O): 7.90 (1H, s, H-8), 4.99 (1H, dd, CH-2⁰, J_{2 1 a} 3.8,

0

J_{2 1 b} 6.2), 4.34 (1H, dd, CH₂-1⁰, J_{1 a2} 3.8, J_g 14.6), 4.24 (1H, dd, CH₂-

0

1⁰, J_{1 b2} 6.2, J_g 14.6), 3.86 (1H, m, OCH₂), 3.72 (1H, dd, P-CH₂,

J_PCHa 9.1, J_g 12.2), 3.62 (3H, m, OCH₂), 3.55 (1H, dd, P-CH₂,

J_PCHa 9.6, J_g 12.2).

0

9-N-(2-Phenylthio-2-phosphonomethoxyethyl)adenine (22) and tetraisopropyl

2-phenylthio-1,1-bis-(phosphonomethoxy)ethane (10)

(i): A mixture of diisopropyl 2-bromo-1-fenylthioethoxymethanepho-

sphonate (11b) (2.045 mmol) and sodium salt of adenine (1.86 mmol), pre-

pared by heating of adenine (0.25 g, 1.86 mmol) with sodium hydride (0.075 g,

1.86 mmol) in DMF at 80 ^ꢀC for 30 minutes, was stirred at room temperature

until diisopropyl 2-bromo-1-fenylthioethoxymethanphosphonate (11b)

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1517

disappeared.The course of the reaction was checked by TLC in ethylacetate-

acetone-ethanol-water (12:2:2:1).Reaction mixture was concentrated invacuo

and oily residue chromatographed on a silica gel column in ethanol-chloro-

form mixture (0710%).Obtained protected adenine nucleotide 12 (X S;

B adenine) was treated with bromotrimethylsilane in acetonitrile at room

temperature.The course of the transesteri®cation reaction was checked by

TLC in isopropanol-conc.aqueous ammonia-water (7:1:2).The reaction

mixture was evaporated and bis(trimethylsilyl) ester groups were hydrolyzed

inwater-methanol-triethylamine mixture (5:5:2).After 30 min of standing, the

solution was concentrated in vacuo.The crude free phosphonate 22 was

puri®ed on DEAE-Sephadex A25 column (166200 mm) by elution with

linear gradient of triethylammonium hydrogencarbonate pH 7.5 (070.2 M,

261000 ml) in water.Fractions containing the product were collected and

evaporated.Pure phosphonate was converted into the sodium salt on Dowex

50 (Na).Yield 00. 87 g (9%) of product 22.

Anal.Calcd.for C ₁₄C₁₅N₅O₄PSNa.4H₂O (475.39): C, 35.4, H, 4.9, N,

14.7, P, 6.5. Found: C, 35.2, H, 4.52, N, 14.44, P, 6.7. MS (FAB): 382.3

(MH ).¹H NMR (D₂O): 8.15 and 8.07 (261H, s, H-2 a H-8), 7.0576.90 (5H, m,

arom H), 5.83 (1H, dd, J_{2 ,1 a} 9.3, J_{2 ,1 b} 3.2, H-2⁰), 3.96 (1H, dd, J_{1 a,2} 9.3,

0

J_g 15.1, H-1⁰a), 3.62 (1H, dd, J_{1 b, 2} 3.2, J_g 15.1, H-1 b), 3.54 (1H, dd,

J_P,CHa 9.5, J_g 12.7, P-CHa), 3.44 (1H, dd, J_P,CHb 9.3, J_g 12.7, P-CHb).

(ii): A mixture of diisopropyl 2-bromo-1-fenylthioethoxymethanepho-

sphonate (11b) (0.59 g, 1.55 mmol), adenine (0.6 g, 4.44 mmol) and cesium

carbonate (1.4 g, 4.44 mmol) in DMF was heated at 110 ^ꢀC for 8 hours.

Reaction mixture was concentrated in vacuo and the residue chromato-

graphed on a silica gel column in ethanol-chloroform mixture (0710%).

Besides unchanged adenine, only the phosphonate 10 was isolated from the

mixture in very low yield.

0

¹H NMR (DMSO-d₆): 7.37 (2H, d, arom H), 7.31 (2H, t, arom H) 7.20

(1H, t, arom H), 4.83 (1H, t, J 5.4, O-CH-O), 4.60 (4H, m, P-OCH), 3.89

(2H, dd, J_P,CH 9.3, J_g 13.7, P-CH₂), 3.81 (2H, dd, J_P,CH 9.8, J_g 13.7,

P-CH₂), 3.21 (2H, d, J 5.4, S-CH₂), 1.26-1.23 (24 H, m, CH₃).¹³C NMR:

102.71 (t, J_{P, C} 12.7, O-C-O), 70.54 (2C, d, P-OC), 70.52 (2C, d, J_P,C 6.8,

P-OC), 59.82 (2C, d, J_P,C 167.0, P-C), 35.19 (S-C), 23.99 (2C, d, CH₃),

23.98 (2C, J_P-C 3.9, CH₃), 23.91 (2C, d, CH₃), 23.88 (2C, d, J_P,C 4.9,

CH₃), arom C: 136.08, 129.27, 2C, 128.54, 2C, 126.14.

9-N-(2-phenyloxy-2-phosphonomethoxyethyl)adenine (23a)

Preparation ofsynthon 11a: 1M solution of bromine in dichloromethane

(30 ml, 30 mmol of Br₂) was added dropwise during 30 minutes to the solution

of diisopropyl vinyloxymethanephosphonate (6) (6.9 g, 30 mmol) in dichlor-

omethane (70 ml) at À 78 ^ꢀC under argon atmosphere.Then a solution of

1518

REJMAN ET AL.

phenol (3.4 g, 36 mmol) and N-ethyldiisopropylamine (6.7 ml, 39 mmol) in

dichloromethane (30 ml) was added at low temperature, and the reaction

mixture was set aside overnight at room temperature.Resulting clear solution

was washed with saturated aqueous solution of sodium hydrogencarbonate.

Organic layer was dried over sodium sulfate and concentrated in vacuo.The

product was isolated on silica gel column in 0750% of acetone in toluene.Yield

7.59 g, (64%) of diisopropyl 2-bromo-1-phenyloxyethoxymethanepho-

sphonate (11a) which was used without characterization for further reaction.

Reaction of compound 11a (2.33 g, 5.9 mmol) with adenine (0.8 g,

5.9 mmol) performed according to Method B followed by deprotection and

puri®cation (Method C ) aorded 0.3 g (13.9%) of compound 23a.

Anal.calcd.for C ₁₄C₁₅N₅O₅PNa.5=2H₂O (432.32): C, 37.3, H, 4.9, N,

15.6, P, 6.9. Found: C, 37.58, H, 4.75, N, 15.63, P, 6.57. MS (FAB): 365.297

(M ).¹H NMR (D₂O): 8.12 s, 1H a 8.05 s, 1H (H-2 a H-8), 7.14 t, 2H a 6.93 t,

1H a 6.75 d, 2H (arom H), 5.70 dd, 1H, J (2⁰, 1⁰a) 3.2, J (2⁰,1⁰b) 6.3 (H-2⁰),

4.57 dd, 1H, J (1⁰a, 2⁰) 3.2, J (gem) 14.7 (H-1⁰a), 4.51 dd, 1H, J (1⁰b,

2⁰) 6.3, J (gem) 14.7 (H-1⁰b), 3.88 dd, 1H, J (P, CHa) 9.3, J (gem) 12.9

(P-CHa), 3.68 dd, 1H, J (P, CHb) 10.0, J (gem) 12.9 (P-CHb).

9- N-(2-phenyloxy-2-phosphonomethoxyethyl)cytosine (23b)

Alkylation with the diisopropyl 2-bromo-1-phenyloxyethoxymetha-

nphosphonate (11a; for preparation see comp.23a) (1.78 g, 4.5 mmol), per-

formed according to Method B with cytosine (0.5 g, 4.5) followed by

deprotection and puri®cation (Method C ) aorded 0.523 g (34%) of product

23b.HR FAB calcd for C ₁₃C₁₅N₂O₇P 341.077673, found 386.049388 (M-

H2Na).

¹H NMR (D₂O): 7.67 (1H, d, H-6, J₅₆ 7.3), 7.36 (2H, t, arom), 7.10

(1H, t, arom), 6.94 (2H, d, arom), 5.92 (1H, d, H5), 5.62 (1H, dd, CH-2⁰,

J_{2 1 a} 3.7, J_{2 1 b} 6.6), 4.31 (1H, dd, CH₂-1⁰, J_{1 a2} 3.7, J_g 14.3), 4.02 (1H,

0

dd, CH₂-1⁰, J_{1 b2} 6.6, J_g 14.3), 3.81 (1H, dd, P-CH₂, J_PCHa 9.3,

J_g 12.0), 3.52 (1H, dd, CH₂-1⁰, J_PCHb 10, J_g 12.0).¹³C NMR: 169.21 (C-

4), 159.445 (arom), 153.72 (C-2), 150.60 (C-6), 132.62 (2C, arom), 125.68

(arom), 119.89 (2C, arom), 98.20 (C-5), 104.32 (C-2⁰, d, J 12.4), 69.06 (P-C,

d, J 150.6), 54.72 (C-1⁰).

0

2,6-diamino-9-N-(2-phenyloxy-2-phosphonomethoxyethyl)purine (23c)

Reaction of diisopropyl 2-bromo-1-phenyloxyethoxymethanepho-

sphonate (11a; for preparation see comp. 23a) (2.27 g, 5.74 mmol) with 2,6-

diaminopurine (0.9 g, 6 mmol) performed according to Method B followed by

deprotection and puri®cation (Method C ) aorded 0.966 g (43.1%) of pro-

duct 23c.

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1519

HR FAB calcd for C₁₄H₁₇N₆O₅P 380.099806, found 381.107631

(MH).¹H NMR (D₂O): 7.86 (1H, s, H-8), 7.21 (2H, t, arom), 6.98 (1H, t,

arom), 6.80 (2H, d, arom), 5.76 (1H, dd, CH-2⁰, J_{2 1 a} 2.9 and J_{2 1 b} 7.0),

0

0 0

4.50 (1H, dd, CH₂-1⁰, J_{1 a2} 2.9, J_g 14.6), 4.39 (1H, dd, CH₂-1 , J_{1 b2} 7.0,

J_g 14.6), 3.86 (1H, dd, P-CH₂, J_PCHa 9.2, J_g 12.1), 3.61 (1H, dd, CH₂-1⁰,

J_PCHb 9.6, J_g 12.1),¹³C NMR: 162.49 (C-2), 158.81 (arom), 158.51 (C-6),

153.93 (C-4), 143.31 (C-8), 132.18 (2C, arom), 125.49 (arom), 119.65 (2C,

arom), 115.22 (C-5), 104.17 (C-2⁰,d, J 11.9), 68.61 (P-C, d, J 151.6), 48.58

(C-1⁰).

0

9-N-(2-phenyloxy-2-phosphonomethoxyethyl)guanine (23d)

Reaction of diisopropyl 2-bromo-1-phenyloxyethoxymethanepho-

sphonate (11a; for preparation see comp. 23a) (1.86 g, 4.7 mmol) with 2-

amino-6-chloropurine (0.8 g, 4.7 mmol) performed according to Method B

followed by deprotection and puri®cation (Method D) aorded 0.437 g

(24.4%) of product 23d.

HR FAB calcd for C14H16N5O6P 381.083821, found 382.091647

(MH).¹H NMR (D₂O): 7.87 (1H, s, H-8), 7.26 (2H, t, arom), 7.03 (1H, t,

arom), 6.88 (2H, d, arom), 5.76 (1H, dd, CH-2⁰, J 3.5 and 6.4), 4.48 (1H,

0

dd, CH₂-1⁰, J_{1 a2} 3.5, J_g 14.7), 4.41 (1H, dd, CH₂-1 , J_{1 b2} 6.4,

J_g 14.7), 3.93 (1H, dd, P-CH₂, J_PCHa 9.4, J_g 12.7), 3.73 (1H, dd, CH₂-1⁰,

J_PCHb 9.6, J_g 12.7),¹³C NMR: 161.37 (C-6), 158.56 (arom), 156.20 (C-2),

154.40 (C-4), 143.22 (C-8), 132.26 (2C, arom), 125.73 (arom), 119.78 (2C,

arom), 118.21 (C-5), 103.71 (C-2⁰,d, J 12.4), 67.21 (P-C, d, J 155.7), 48.48

(C-1⁰).

0

1-N-(2-phenyloxy-2-phosphonomethoxyethyl)thymine (23e)

Reaction of diisopropyl 2-bromo-1-phenyloxyethoxymethanepho-

sphonate (11a; for preparation see comp. 23a) (1.86 g, 4.7 mmol) with thy-

mine (0.6 g, 4.7 mmol) performed according to Method B followed by

deprotection and puri®cation (Method C ) aorded 0.23 g (13.7%) of product

23e.

HR FAB calcd for C₁₄H₁₇N₂O₇P 356.077339, found 379.067109

(MNa).¹H NMR (D₂O): 7.55 (1H, d, H-6, J₅₆ 7.9), 7.38 (2H, t, arom),

7.12 (1H, t, arom), 6.98 (2H, d, arom), 5.68 (1H, dd, CH-2⁰, J 4.0 and 6.2),

0

4.22 (1H, dd, CH₂-1⁰, J_{1 a2} 4.0, J_g 14.4), 4.09 (1H, dd, CH₂-1 , J_{1 b2} 6.2,

J_g 14.4), 3.88 (1H, dd, P-CH₂, J_PCHa 9.4, J_g 12.7), 3.68 (1H, dd, CH₂-1⁰,

J_PCHb 9.7, J_g 12.7). 1.83 (3H, d, CH₃),¹³C NMR: 169.46 (C-4), 158.88

(arom), 154.98 (C-2), 149.37 (C-6), 132.55 (2C, arom), 125.81 (arom), 119.825

(2C, arom), 113.14 (C-5), 103.52 (C-2⁰,d, J 12.8), 67.40 (P-C, d, J 155.2),

52.99 (C-1⁰), 13.72 (CH₃).

0

1520

REJMAN ET AL.

1-N-(2-phenyloxy-2-phosphonomethoxyethyl)uracil (23f)

Alkylation with the diisopropyl 2-bromo-1-phenyloxyethoxymethane-

phosphonate (11a; for preparation see comp. 23a) (1.86 g, 4.7 mmol), per-

formed according to MethodB with uracil (0.53 g, 4.7) followed by deprotection

and puri®cation (Method C ), aorded 0.16 g (10%) of product 23f.

HR FAB calcd for C₁₃H₁₅N₂O₇P 342.061689, found 365.051459

(MNa).¹H NMR (D₂O): 7.73 (1H, d, H-6, J₅₆ 7.9), 7.39 (2H, t, arom),

7.14 (1H, t, arom), 7.11 (2H, d, arom), 5.79 (1H, d, H5), 5.65 (1H, dd, CH-2⁰,

J 4.4 and 5.6), 4.23 (1H, dd, CH₂-1⁰, J_{1 a2} 4.4, J_g 14.6), 4.14 (1H, dd,

0

CH₂-1⁰, J_{1 b2} 5.6, J_g 14.6), 3.89 (1H, dd, P-CH₂, J_PCHa 9.4, J_g 12.6),

3.66 (1H, dd, CH₂-1⁰, J_PCHb 9.8, J_g 12.7).¹³C NMR: 169.295 (C-4), 158.86

(arom), 154.91 (C-2), 150.63 (C-6), 132.6 (2C, arom), 125.89 (arom), 119.90

(2C, arom), 104.04 (C-5), 103.48(C-2⁰,d, J 12.8), 67.27 (P-C, d, J 156.1),

52.95 (C-1⁰).

0

9-N-(2-azido-2-phosphonomethoxyethyl)adenine (24)

The chloroiodide (0.81 g, 5 mmol) was added under vigorous stirring to

a suspension of sodium azide (0.4 g, 6 mmol) in dimethylformamide (5 ml) at

0 ^ꢀC.After 30 min, the diisopropyl vinyloxymethanephosphonate ( 6) (1.1 ml,

5 mmol) was added, and the reaction mixture was kept at room temperature

for 16 hrs.The resulting suspension was diluted with ether (50 ml), and this

solution was subsequently washed with saturated aqueous solutions of

sodium hydrogencarbonate and sodium thiosulfate.Ether layer was dried

with sodium sulfate and evaporated.A crude diisopropyl 1-azido-2-iodoe-

thoxymethanephosphonate (13) was puri®ed on a silica gel column in 0710%

of ethanol in chloroform, and the obtained product was treated with sodium

salt of adenine, prepared by heating of adenine (0.31 g, 2.27 mmol) and

sodium hydride (0.092 g, 2.27 mmol) in DMF (20 ml) at 80 ^ꢀC for 30 min.The

reaction mixture was stirred at room temperature overnight, and the reaction

course was checked by TLC in ethylacetate-acetone-ethanol-water (12:2:2:1).

Reaction mixture was concentrated in vacuo and the residue chromato-

graphed on a silica gel column in 0710% of ethanol in chloroform.The

product was deprotected according to Method C. Yield 0.033 g (1.6%) of

compound 24.

Anal.calcd.for C ₈H₁₀N₈O₄PNa.4H₂O (408.24): C, 23.50, H, 4.40, N,

27.40. Found: C, 23.56, H, 4.43, N, 26.71. MS (FAB): 315.1 (MH ).¹H NMR

0

(D₂O): 8.25 and 8.23 (261H, s, H-2 a H-8), 5.20 (1H, t, J_{2 ,1} 4.6, H-2 ),

0

4.55 (1H, dd, J_{1 a,2} 4.6, J_g 14.7, H-1 a), 4.51 (1H, dd, J_{1 b,2} 4.6,

J_g 14.7, H-1⁰b), 3.91 (1H, dd, J_P,CHa 9.5, J_g 12.7, P-CHa), 3.70 (1H, dd,

J_P,CHb 9.5, J_g 12.7, P-CHb).¹³C NMR: 155.76 (C-6), 152.80 (C-2), 149.50

(C-4), 143.54 (C-8), 118.29 (C-5), 90.53 (d, J_P,C 12.7, C-2⁰), 65.97 (d,

J_P,C 155.3, P-C), 46.58 (C-1⁰).

N-(2-PHOSPHONOMETHOXYETHYL)PURINES

1521

Diisopropyl 1-acetoxy-2-iodoethoxymethanephosphonate (52)

N-iodosuccinimide (0.496 g, 2.2 mmol) was added under argon atmo-

sphere to a solution of vinylacetate (50) (0.172 g, 2 mmol) and diisopropyl

hydroxymethanephosphonate [9] (51) (0.432 g, 2.2 mmol) in dichloromethane

at 0 ^ꢀC, and the reaction was set aside at room temperature for 16 hrs.The

solution was washed with sodium hydrogencarbonate, organic layer dried

with anhydrous sodium sulfate, and evaporated.Chromatography of the

residue on a silica gel column in 0750% of acetone in toluene aorded

0.117 g (14.3%) of compound 52.

MS (FAB): 409.5 (MH ).¹H NMR (DMSO-d₆): 5.71 (1H, t, J 4.9, O-

CH-O), 4.62 (2H, m, P-OCH), 3.97 (1H, dd, J₁ 9.3, J₂ 13.7, 3.89 (1H, dd,

J₁ 9.0, J₂ 13.7, P-CH₂), 3.43 (2H, d, J 4.9, CH₂-I), 2.08 (3H, s, CH₃),

1.26 (12 H, d, J_CH3,CH 6.1, CH₃).¹³C NMR: 170.09 (C O), 96.22 (d, J_P,

12.7, O-C-O), 70.77 (d, P-OC), 70.72 (d, J_{P, C} 5.9, P-OC), 62.67 (d, J_P,

C

166.0, P-C), 24.01 (d, CH₃), 23.98 (d, CH₃), 23.90 (d, CH₃), 23.87 (d, J_P,

C

3.9, CH₃), 20.89 (CH₃), 4.96 (C-I).

C

ACKNOWLEDGMENTS

This work was supported by grant No.NL5441-3 of the Grant Agency

of Ministry of Health Czech Republic, and by Gilead Science, CA, U.S.A..

The authors are indebted to Dr.Ivan Votruba and Dr.Jitka Kohoutova ,

Â

both of this Institute, for the evaluation of cytostatic properties of prepared

compounds and mass spectra measurements, respectively.Special thanks are

given to the Department of Health & Human Services (NIH, NCI), MD,

U.S.A. for anticancer assays of selected compounds, and to Dr. Zdene

Tocik of this Institute for valuable discussion and help at the preparation of

the manuscript.

Ï

k

Ï

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Received May 25, 2000

Accepted December 30, 2000

Article Doi

2'C-alkoxy and 2'-C-aryloxy derivatives of N-(2-phosphonomethoxyethyl)-purines and -pyrimidines: synthesis and biological activity.

DOI: 10.1081/NCN-100105244

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Full text of DOI:10.1081/NCN-100105244

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