Hydrogenphosphonate synthesis of sugar phosphomonoesters

Article abstract of DOI:10.1039/b000727g

A highly efficient procedure for the phosphorylation of sugar hydroxy derivatives has been developed. A four-step sequence comprising H-phosphonate formation, pivaloyl chloride-mediated coupling with fluoren-9-ylmethanol, oxidation, and cleavage of the fiuoren-9-ylmethyl ester led to the sugar monophosphate derivatives 4a-g in 83-93% yield. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b000727g

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Hydrogenphosphonate synthesis of sugar phosphomonoesters
Dmitry V. Yashunsky and Andrei V. Nikolaev*
Department of Chemistry, University of Dundee, Dundee, UK DD1 4HN
1
Received (in Cambridge, UK) 26th January 2000, Accepted 7th March 2000
Published on the Web 30th March 2000
A highly efficient procedure for the phosphorylation of sugar hydroxy derivatives has been developed. A four-step
sequence comprising H-phosphonate formation, pivaloyl chloride-mediated coupling with fluoren-9-ylmethanol,
oxidation, and cleavage of the fluoren-9-ylmethyl ester led to the sugar monophosphate derivatives 4a–g in 83–93%
yield.
(Scheme 1) to produce the phosphomonoesters 4a–4g, respect-
Introduction
ively, via the consecutive preparation of the H-phosphonates
2a–2g and the monosaccharide fluoren-9-ylmethyl phospho-
diesters 3a–3g.
The key roles that carbohydrate phosphates play in Nature,
both as components of nucleic acids and various coenzymes,
and in the biosynthesis and metabolism of sugars, make
novel methods for their preparation of great value. There is an
abundant literature on phosphorylation procedures1 including
reports of chemical syntheses of sugar phosphomonoesters
from hydroxylic derivatives using phosphomonoester (phos-
The monohydroxylic carbohydrate derivatives 1a–1g were
first H-phosphonylated by reaction (30 min) with triimid-
azolylphosphine (prepared in situ from PCl3, imidazole and
Et3N) followed by mild hydrolysis to give the H-phosphonates
2a–2g, respectively, in excellent 93–100% yield. Signals
characteristic of the H-phosphonate group (δP 1.87–5.79;
phoryl
trichloride–N-ethylmorpholine),2
phosphodiester
(β-cyanoethyl phosphate–condensing agent, e.g. DCC, TPSCl,
etc.),3 phosphotriester [diphenyl phosphorochloridate,4
dibenzyl phosphorochloridate,5 or bis(2,2,2-trichloroethyl)
phosphorochloridate6 in pyridine] and phosphoramidite
(dibenzyl diisopropylphosphoramidite–1H-tetrazole followed
by oxidation)7 methods with moderate to high efficiency. In
addition, sugar phosphates can be prepared enzymically.8
The highly efficient hydrogenphosphonate (H-phosphonate)
synthesis of phosphoric diesters (involving the formation
of H-phosphonic monoesters9,10 from alcohols followed by
esterification with the second alcohol to form H-phosphonic
diesters11 and oxidation with iodine–pyridine–water system12)
is well established and widely used in many synthetic projects
towards oligonucleotides13 and sugar phosphodiesters.10,14–17
The principal advantages of the H-phosphonate approach are
both high efficiency and high reaction rate for all three chemical
steps involved.
It is worthy to note that, unlike the rapid oxidation of the
H-phosphonic diesters to phosphoric diesters with iodine, the
transformation of the H-phosphonic monoesters to phosphates
requires trimethylsilylation (to form the corresponding bis-
trimethylsilyl alkyl phosphites) prior to the oxidation to
phosphoric triesters, followed by hydrolysis of the trimethylsilyl
groups.12,18 The latter approach did not find widespread
application for a preparative synthesis of organic phosphates,
probably because the efficiency of the presilylation can be
monitored by 31P NMR only.
δH 6.67–7.14; JP, H 624–650 Hz) were present in the 31P and
1
1H NMR spectra of the compounds. The H-phosphonic
monoesters 2a–2g were then converted to the fluoren-9-
ylmethyl phosphodiesters 3a–3g (91–97%; δP between Ϫ1.85
and 0.74), respectively, by esterification (30 min) with fluoren-9-
ylmethanol (2.5 equiv.) in pyridine in the presence of trimethyl-
acetyl chloride followed by in situ oxidation (30 min) of the
resulting H-phosphonic diesters with iodine in aq. pyridine.
The targeted phosphomonoesters 4a–4g were prepared from
the diesters 3a–3g, respectively, by mild cleavage (30 min) of the
fluoren-9-ylmethyl group with piperidine in dichloromethane
(1:5 v/v) in superior 94–100% yield.
Because of the high efficiency of each step, the whole reaction
sequence benefits from the absence of any chromatographic
isolation for the purification of both the intermediates 2a–2g
and 3a–3g, and the final products 4a–4g (see Experimental
section). All the chemical transformations could be easily
monitored by TLC.
The described procedure led smoothly to the sugar phos-
phates 4a–g in 83–93% total yield starting from the correspond-
ing monohydroxylic derivatives. All the reactions proceeded
rapidly and very efficiently, including transformation of com-
pounds 1b, 1f and 1g containing sterically hindered hydroxy
groups at C-4. Similar phosphorylation of the diol 1h provided
the corresponding 2,3-diphosphate 4h in 71% yield. It should
be noted that the fluoren-9-ylmethyl P-protecting group could
be cleaved under extremely mild conditions which do not
affect O-benzyl, O-benzylidene, O-benzoyl or O-acetyl protect-
ing groups. In contrast, cleavage of the most widely used P-
protecting groups1,3–5,7 requires either hydrogenation (for
benzyl, dibenzyl and diphenyl phosphates), or basic treatment
(for phenyl, 2- and 4-chlorophenyl and β-cyanoethyl phos-
phates), which may not be compatible with generic synthetic
strategy.
Results and discussion
The above findings urged us to examine the applicability of the
H-phosphonate approach for the phosphorylation of primary,
secondary and anomeric HO-groups of carbohydrates using a
fluoren-9-ylmethyl ester as P-protecting group19–21 to facilitate
the oxidation step. The protecting group could then be easily
removed with piperidine to provide the desired phospho-
monoesters. We now report a novel, efficacious method for
O-phosphorylation of the model hydroxylic derivatives 1a–1g
The structures of the sugar phosphates 4a–4h were confirmed
by NMR and mass spectrometry data (see Experimental
section). Signals in the 31P NMR spectra appeared as a triplet
(3JP, H 5.6 Hz) for compound 4a and as a doublet (3JP, H 6–11
DOI: 10.1039/b000727g
J. Chem. Soc., Perkin Trans. 1, 2000, 1195–1198
This journal is © The Royal Society of Chemistry 2000
1195

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Scheme 1 Reagents: i, (a) triimidazolylphosphine, MeCN; (b) Et3NHHCO3, water (pH 7); ii, (a) fluoren-9-ylmethanol, pivaloyl chloride, pyridine;
(b) I2, pyridine–water; iii, piperidine, CH2Cl2.
Hz) for the derivatives 4b–h at δP between 0.28 and 4.19 and
were characteristic of phosphomonoesters. The position of the
phosphate group (O-1, -2, -3, -4, or -6) was clearly indicated
using an Ion-tech xenon gun. Filtration of solutions through a
silica gel pad was performed on Kieselgel 60 (0.040–0.063 mm)
(Merck). TLC was performed on Kieselgel 60 F254 (Merck) with
A, dichloromethane–methanol (3:1) and B, dichloromethane–
methanol (9:1). Dichloromethane, acetonitrile and pyridine
were freshly distilled from CaH2. Solutions worked up were
concentrated under reduced pressure at <40 ЊC. Petroleum
spirit refers to that fraction with distillation range 60–80 ЊC.
1
by the signals of the corresponding H-atoms in the H NMR
spectra. These signals were shifted as a result of the phos-
phorylation and were coupled with phosphorus. The signals
in the ES(Ϫ) mass spectra of the monophosphates 4a–4g
corresponded to the pseudo-molecular ion [M Ϫ H]Ϫ for the
compounds. The signals in the FAB(ϩ) mass spectrum of the
2,3-diphosphate 4h were consistent with the molecular mass
of the derivative.
Methyl 2,3,4-tri-O-benzoyl-ꢀ-D-glucopyranoside 6-phosphate,
dipiperidinium salt 4a
In conclusion, we report a novel, fast and simple method for
the phosphorylation of sugar hydroxylic derivatives based on
H-phosphonate chemistry.9–14 The method can be considered as
a useful alternative to the traditional procedures,1–8 because it
appears to be (1) equally highly efficient for all three major
types of HO-group (primary, secondary and anomeric) present
in carbohydrates and (2) fully compatible with principal types
of O-protecting groups.
To a stirred solution of imidazole (538 mg, 7.90 mmol, 7 equiv.)
in MeCN (15 cm3) at 0 ЊC was added phosphorus trichloride
(0.18 cm3, 2.07 mmol, 5.5 equiv.) and then triethylamine (1.18
cm3, 8.46 mmol, 7.5 equiv.). The mixture was stirred for 15 min,
after which a solution of compound 1a (192 mg, 0.376 mmol) in
MeCN (6 cm3) was added dropwise during 10 min at 0 ЊC. The
mixture was stirred at rt for 20 min and quenched with 1 mol
dmϪ3 triethylammonium (TEA) hydrogen carbonate (pH 7; 6
cm3). The clear solution was stirred for 15 min, CH2Cl2 (70 cm3)
was added, and the organic layer was washed in turn with
ice–water and cold 0.5 mol dmϪ3 TEA hydrogen carbonate,
dried by filtration through cotton wool, and concentrated to give
the pure H-phosphonate 2a (254 mg, 100%) as an amorphous
solid, δP 4.95 (dt, 1JP, H 623.8, 3JP, H 7.5); δH 6.93 (d, HP).
The H-phosphonate 2a (214 mg, 0.317 mmol) was dissolved
in pyridine (5 cm3), fluoren-9-ylmethanol (156 mg, 0.793 mmol,
2.5 equiv.) was added followed by the addition of pivaloyl
chloride (0.156 cm3, 1.27 mmol, 4 equiv.), and the mixture was
stirred at rt for 30 min, whereafter a freshly prepared solution
of iodine (160 mg, 0.63 mmol, 2 equiv.) in pyridine–water
(95:5; 3 cm3) was added. After 30 min, CH2Cl2 was added and
Experimental
General procedures
Optical rotations were measured with a Perkin-Elmer 141
polarimeter; [α]D-values are given in units of 10Ϫ1 deg cm2 gϪ1
.
NMR spectra (1H at 300 MHz and 31P at 121 MHz) were
recorded with a Bruker DPX-300 spectrometer for solutions in
CDCl3. Chemical shifts (δ in ppm) are given relative to those for
1
Me4Si (for H) and external aq. 85% H3PO4 (for 31P); J-values
are given in Hz. ES mass spectra were recorded with a Micro-
mass Quattro system (Micromass Biotech, UK). FAB mass
spectra were recorded with a VG 70–250 SE mass spectrometer
1196
J. Chem. Soc., Perkin Trans. 1, 2000, 1195–1198

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the solution was washed successively with ice-cold 1 mol dmϪ3
aq. Na2S2O3 and cold 0.5 mol dmϪ3 aq. TEA hydrogen carb-
onate, dried by filtration through cotton wool, and concen-
trated. A solution of the residue in toluene–ethyl acetate (7:3)
was passed through a silica gel pad using, first, the same solvent
and then dichloromethane–methanol (9:1) for the elution.
The DCM–MeOH fraction was washed with 0.5 mol dmϪ3 aq.
TEA hydrogen carbonate and concentrated to produce the
phosphodiester 3a (265 mg, 97%) as a chromatographically
homogeneous amorphous solid, δP Ϫ0.54 (quintet, JP, H 4.7).
The phosphodiester 3a (50 mg, 0.058 mmol) was dissolved
in CH2Cl2 (2.0 cm3), piperidine (0.4 cm3) was added, and the
mixture was kept at rt for 30 min and then concentrated at 0.01
mmHg (oil-pump). A solution of the residue in methanol–
petroleum spirit (1:2; 50 cm3) was extracted with water (20 cm3)
and the aqueous layer was concentrated to give the phospho-
monoester 4a (41 mg, 95%; 92% based on compound 1a) as a
chromatographically pure amorphous solid, [α]D24 ϩ36 (c 1,
CHCl3); Rf 0.38 (solvent A); δH 1.55 (4 H, br, 2 × CH2-
CH2CH2N), 1.75 (8 H, br, 4 × CH2CH2N), 3.00 (8 H, br,
4 × CH2N), 3.46 (3 H, s, OMe), 3.95 (1 H, dt, J5,6a = J6a,P = 5.6,
6-Ha), 4.03 (1 H, ddd, J6b,P 5.6, J6a,6b 11.3, 6-Hb), 4.26 (1 H, ddd,
J5,6b 2.1, 5-H), 5.16 (1 H, d, J1,2 3.5, 1-H), 5.21 (1 H, dd, J2,3 10.1,
2-H), 5.52 (1 H, t, J3,4 = J4,5 = 9.7, 4-H), 6.12 (1 H, dd, 3-H) and
7.20–8.00 (15 H, m, 3 × Ph); δP 3.18 (t, J 5.6); ES-MS(Ϫ) m/z
584.89 (100%, [M Ϫ H]Ϫ) (free acid C28H27O12P requires M,
586.12).
dd, 2-H), 3.90 and 4.12 (AB, Jgem 12.2, 6-Ha and 6-Hb), 4.31
(1 H, dt, J2,3 = J3,P = 9.6, 3-H), 4.44 (1 H, d, J1,2 7.6, 1-H), 4.52
(1 H, d, J3,4 3.1, 4-H), 4.76 and 4.86 (AB, Jgem 11.2, PhCH2),
5.54 (1 H, s, PhCH) and 7.10–7.60 (10 H, m, 2 × Ph); δP 2.14
(d, J 9.6); ES-MS(Ϫ) m/z 451.03 (100%, [M Ϫ H]Ϫ) (free acid
C21H25O9P requires M, 452.12).
Methyl 3-O-benzoyl-4,6-O-benzylidene-ꢁ-D-galactopyranoside
2-phosphate, dipiperidinium salt 4d
This compound was prepared from compound 1d (100 mg) via
the consecutive formation of the H-phosphonate 2d [134 mg,
96%; δP 3.29 (dd, 1JP, H 641.8, 3JP, H 10.8); δH 6.95 (d, HP)] and the
phosphodiester 3d [177 mg, 97%; δP Ϫ1.41 (dt, JP,CH 5.9, JP,2-H
2
10.3)] followed by P-deprotection of the derivative 3d (40 mg)
as described for the preparation of the phosphate 4a. This
produced the phosphomonoester 4d (34 mg, 100%; 93% based
on compound 1d) as a chromatographically pure amorphous
solid, [α]D24 ϩ52 (c 1, CHCl3); Rf 0.43 (solvent A); δH 1.52 (4 H, br,
2 × CH2CH2CH2N), 1.78 (8 H, br, 4 × CH2CH2N), 3.00 (8 H,
br, 4 × CH2N), 3.55 (3 H, s, OMe), 3.62 (1 H, s, 5-H), 4.07 and
4.34 (AB, Jgem 12.5, 6-Ha and 6-Hb), 4.49 (1 H, J1,2 7.8, 1-H),
4.52 (1 H, d, 4-H), 4.55 (1 H, dt, J2,3 = J2,P = 9.8, 2-H), 5.15 (1 H,
dd, J3,4 3.5, 3-H), 5.47 (1 H, s, PhCH) and 7.10–8.20 (10 H,
m, 2 × Ph); δP 1.39 (d, J 9.8); ES-MS(Ϫ) m/z 464.99 (100%,
[M Ϫ H]Ϫ) (free acid C21H23O10P requires M, 466.10).
2,3,4,6-Tetra-O-benzyl-ꢀ,ꢁ-D-glucopyranosyl phosphate, mono-
piperidinium salt 4e
1,2,3,6-Tetra-O-benzoyl-ꢀ-D-mannopyranose 4-phosphate,
This compound was prepared from compound 1e (100 mg;
anomeric mixture, α:β ≈ 3.4:1) via the consecutive formation
of the H-phosphonate 2e [254 mg, 99%; δP 1.87 (dd, 1JP, H 649.0,
3JP, H 8.3, Pα) and 2.29 (dd, 1JP, H 650.4, 3JP, H 9.1, Pβ); δH 7.08 (d,
HPα) and 7.14 (d, HPβ); α:β ≈ 3.4:1] and the phosphodiester
bis(triethylammonium) salt 4b
The tetrabenzoate 1b (100 mg) was first converted to the H-
phosphonate 2b [117 mg, 93%; δP 4.71 (dd, JP, H 632.6, JP, H
11.3); δH 6.99 (d, HP)] and then to the phosphodiester 3b
[139 mg, 95%; δP Ϫ1.11 (dt, JP,CH 5.4, JP,4-H 9.7)] as described
in the preparation of the phosphate 4a.
1
3
3e [303 mg, 93%; δP Ϫ1.85 (dt, JP,CH 5.6, JP,1-H 8.2, Pβ) and
2
2
Ϫ1.34 (dt, JP,CH 4.9, JP,1-H 8.0, Pα); α:β ≈ 3.4:1] followed by
2
The phosphodiester 3b (29 mg, 0.031 mmol) was dissolved
in CH2Cl2 (0.5 cm3), piperidine (0.1 cm3) was added and the
mixture was kept at rt for 30 min, then diluted with CH2Cl2,
washed with 0.5 mol dmϪ3 HCl, dried by filtration through
cotton wool, and concentrated. A solution of the residue in
toluene–ethyl acetate (7:3) was passed through a silica gel pad
using, first, the same solvent and then dichloromethane–
methanol (9:1) for the elution. The DCM–MeOH fraction was
washed with 0.5 mol dmϪ3 aq. TEA hydrogen carbonate and
concentrated to produce the phosphomonoester 4b (25 mg,
94%; 83% based on compound 1b) as a chromatographically
pure amorphous solid, [α]D24 ϩ11 (c 1, CHCl3); Rf 0.08 (solvent
B); δH 0.98 (18 H, t, J 7.2, 6 × CH3CH2N), 2.59 (12 H, q,
6 × CH3CH2N), 4.45 (1 H, ddd, J5,6a 6.4, J4,5 9.8, 5-H), 4.64
(1 H, dd, J6a,6b 11.9, 6-Ha), 4.85 (1 H, dd, J5,6b 1.5, 6-Hb), 5.51
(1 H, q, J3,4 = J4,5 = J4,P = 9.8, 4-H), 5.78 (1 H, dd, J1,2 1.9, J2,3
3.4, 2-H), 5.83 (1 H, dd, 3-H), 6.45 (1 H, d, 1-H) and 7.00–8.20
(20 H, m, 4 × Ph); δP 1.26 (d, J 9.8); ES-MS(Ϫ) m/z 675.16
(100%, [M Ϫ H]Ϫ) (free acid C34H29O13P requires M, 676.13).
the P-deprotection of the derivative 3e (64 mg) as described for
the preparation of the phosphate 4a. This produced the
phosphomonoester 4e (48 mg, 94%; 87% based on compound
1e) as an amorphous solid, Rf 0.50 (solvent A); δH (inter alia)
1.40 (2 H, br, CH2CH2CH2N), 1.65 (4 H, br, 2 × CH2CH2N),
3.03 (4 H, br, 2 × CH2N), 5.20 (dd, J1,2 9.8, J1,P 8.0, 1-Hβ) and
5.83 (dd, J1,2 2.4, J1,P 6.0, 1-Hα); δP 0.28 (d, J 8.0, Pβ) and 0.44 (d,
J 6.0, Pα); α:β ≈ 3.4:1; ES-MS(Ϫ) m/z 619.1 (100%, [M Ϫ H]Ϫ)
(free acid C34H37O9P requires M, 620.22).
Methyl 2,3,6-tri-O-benzoyl-ꢁ-D-galactopyranoside 4-phosphate,
dipiperidinium salt 4f
This compound was prepared from compound 1f (160 mg) via
the consecutive formation of the H-phosphonate 2f [208 mg,
1
3
100%; δP 3.84 (dd, JP, H 631.7, JP, H 11.6); δH 6.98 (d, HP)] and
the phosphodiester 3f [260 mg, 96%; δP Ϫ0.59 (dt, JP,CH 5.5,
2
JP,4-H 9.9)] followed by P-deprotection of the derivative 3f (60
mg) as described for the preparation of the phosphate 4a. This
produced the phosphomonoester 4f (51 mg, 97%; 93% based on
compound 1f) as a chromatographically pure amorphous solid,
[α]D24 ϩ28 (c 1, CHCl3); Rf 0.38 (solvent A); δH 1.60 (4 H, br,
2 × CH2CH2CH2N), 1.80 (8 H, br, 4 × CH2CH2N), 3.06 (8 H,
br, 4 × CH2N), 3.44 (3 H, s, OMe), 4.16 (1 H, dd, J5,6a 2.6, J5,6b
8.8, 5-H), 4.47 (1 H, dd, J6a,6b 12.1, 6-Ha), 4.62 (1 H, d, J1,2 7.8,
1-H), 4.66 (1 H, dd, 6-Hb), 4.86 (1 H, dd, J3,4 3.2, J4,P 11.0, 4-H),
5.31 (1 H, dd, J2,3 10.4, 3-H), 5.63 (1 H, dd, 2-H) and 7.20–8.00
(15 H, m, 3 × Ph); δP 2.01 (d, J 11.0); ES-MS(Ϫ) m/z 585.07
(100%, [M Ϫ H]Ϫ) (free acid C28H27O12P requires M, 586.12).
Methyl 2-O-benzyl-4,6-O-benzylidene-ꢁ-D-galactopyranoside
3-phosphate, dipiperidinium salt 4c
This compound was prepared from compound 1c (55 mg) via
the consecutive formation of the H-phosphonate 2c [73 mg,
94%; δP 5.79 (dd, 1JP, H 630.7, 3JP, H 10.7); δH 7.05 (d, HP)] and the
phosphodiester 3c [94 mg, 94%; δP Ϫ0.79 (dt, JP,CH 4.4, JP,3-H
2
8.0)] followed by P-deprotection of the derivative 3c (20 mg)
as described for the preparation of the phosphate 4a. This
produced the phosphomonoester 4c (17 mg, 100%; 88% based
on compound 1c) as a chromatographically pure amorphous
solid, [α]D24 ϩ24 (c 1, CHCl3); Rf 0.40 (solvent A); δH 1.52 (4 H, br,
2 × CH2CH2CH2N), 1.78 (8 H, br, 4 × CH2CH2N), 3.00 (8 H,
br, 4 × CH2N), 3.24 (1 H, s, 5-H), 3.60 (3 H, s, OMe), 3.62 (1 H,
Benzyl 2-acetamido-3,6-di-O-benzoyl-2-deoxy-ꢀ-D-glucopyr-
anoside 4-phosphate, dipiperidinium salt 4g
This compound was prepared from compound 1g (60 mg) via
the consecutive formation of the H-phosphonate 2g [78 mg,
J. Chem. Soc., Perkin Trans. 1, 2000, 1195–1198
1197

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99%; δP 5.65 (dd, 1JP, H 629.0, 3JP, H 11.4); δH 6.67 (d, HP)] and the
Acknowledgements
phosphodiester 3g [91 mg, 91%; δP 0.74 (dt, JP,CH 6.3, JP,4-H 8.6)]
2
This work and D. V. Y. were supported by a Wellcome Trust
International Grant. The research of A. V. N. was supported by
an International Research Scholar’s award from the Howard
Hughes Medical Institute. We are indebted to Dr A. P. Higson
for a helpful discussion.
followed by P-deprotection of the derivative 3g (91 mg) as
described for the preparation of the phosphate 4a. For these
transformations, the following quantities of reagents were
required: PCl3 (9.9 equiv.), imidazole (11.9 equiv.), Et3N (14.5
equiv.), fluoren-9-ylmethanol (4.4 equiv.), trimethylacetyl
chloride (7.1 equiv.) and iodine (3.45 equiv.). This produced the
phosphomonoester 4g (80 mg, 100%; 90% based on compound
1g) as a chromatographically pure amorphous solid, [α]D24 ϩ39
(c 1, CHCl3); Rf 0.39 (solvent A); δH 1.40 (4 H, br, 2 × CH2CH2-
CH2N), 1.60 (8 H, br, 4 × CH2CH2N), 1.86 (3 H, s, Ac), 2.82
(8 H, br, 4 × CH2N), 3.86 (1 H, dt, J5,6a = J5,6b = 3.3, 5-H), 4.23
(1 H, ddd, J2,NH 4.9, 2-H), 4.36 (1 H, dd, J6a,6b 12.0, 6-Ha), 4.48
(1 H, dd, 6-Hb), 4.45 and 4.66 (AB, Jgem 11.6, PhCH2), 4.52
(1 H, q, J3,4 = J4,5 = J4,P = 10.0, 4-H), 5.30 (1 H, t, J2,3 10.0, 3-H),
5.52 (1 H, d, J1,2 3.0, 1-H) and 7.20–8.20 (15 H, m, 3 × Ph); δP
4.19 (d, J 10.0); ES-MS(Ϫ) m/z 598.1 (100%, [M Ϫ H]Ϫ) (free
acid C29H30NO11P requires M, 599.15).
References
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1
1
3JP, H 10.5, PЈ); δH 6.96 (d, JP, H 633.3, HP) and 6.98 (d, JP, H
646.6, HPЈ)] and the 2,3-bisphosphodiester 3h [107 mg, 71%
based on compound 1h; δP 0.54 (dt, JP,CH 4.7, JP, H 9.4) and 1.65
2
(dt, JP,CH 4.4, JP, H 9.0)] followed by P-deprotection of the
2
derivative 3h (53 mg) as described for the preparation of the
phosphate 4a. The following quantities of the reagents per HO-
group were used: PCl3 (6.1 equiv.), imidazole (7.3 equiv.), Et3N
(8.6 equiv.), fluoren-9-ylmethanol (2.7 equiv.), trimethylacetyl
chloride (4.3 equiv.), and iodine (2.1 equiv.). This produced the
2,3-diphosphate 4h (42 mg, 100%; 71% based on compound
1h) as a chromatographically pure amorphous solid, [α]D24 ϩ27 (c
1, CHCl3); Rf 0.21 (solvent A); δH 1.52 (8 H, br, 4 × CH2CH2-
CH2N), 1.78 (16 H, br, 8 × CH2CH2N), 3.00 (16 H, br,
8 × CH2N), 3.53 (1 H, s, 5-H), 3.90 (1 H, dt, J2,3 = J2,P = 9.7,
2-H), 4.18 and 4.27 (AB, Jgem 12.3, 6-Ha and 6-Hb), 4.20 (1 H,
dt, J3,P 9.7, 3-H), 4.37 (1 H, d, J3,4 3.1, 4-H), 4.46 (1 H, d, J1,2
7.7, 1-H), 4.68 and 4.97 (AB, Jgem 12. 0, PhCH2), 5.55 (1 H, s,
PhCH) and 7.10–7.60 (10 H, m, 2 × Ph); δP 4.06 (d, J 9.7);
FAB-MS(ϩ) m/z 279 (60%, [M ϩ K ϩ H]2ϩ), 328 (20, [M ϩ
(CH2)5NH ϩ 3NH3 ϩ 2H]2ϩ), 364 (100, [M ϩ 2 (CH2)5NH ϩ
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K ϩ H]2ϩ) and 524 (30, [M ϩ 6 (CH2)5NH ϩ NH3 ϩ 2 H]2ϩ
(free acid C20H24O12P2 requires M, 518.07).
)
1198
J. Chem. Soc., Perkin Trans. 1, 2000, 1195–1198