Design and synthesis of aryl/hetarylmethyl phosphonate-UMP derivatives as potential glucosyltransferase inhibitors

Article abstract of DOI:10.1016/S0040-4039(01)00974-1

A novel class of glucosyltransferase inhibitors has been designed and synthesised. The designed inhibitors 1-4 provide conformational mimicry of the transition-state in glucosyltransfer reactions. The key synthetic steps involve a Michaelis-Arbuzov reaction followed by coupling with uridine-5′-morpholidophosphate as activated UMP derivative.

Full text of DOI:10.1016/S0040-4039(01)00974-1

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 5393–5395
Design and synthesis of aryl/hetarylmethyl phosphonate-UMP
derivatives as potential glucosyltransferase inhibitors
Asish K. Bhattacharya, Florian Stolz and Richard R. Schmidt*
Fachbereich Chemie, Universita¨t Konstanz, Fach M725, D-78457 Konstanz, Germany
Received 1 June 2001; accepted 6 June 2001
Abstract—A novel class of glucosyltransferase inhibitors has been designed and synthesised. The designed inhibitors 1–4 provide
conformational mimicry of the transition-state in glucosyltransfer reactions. The key synthetic steps involve a Michaelis–Arbuzov
reaction followed by coupling with uridine-5%-morpholidophosphate as activated UMP derivative. © 2001 Elsevier Science Ltd.
All rights reserved.
In recent times, much progress has been made towards
a broader understanding of the functions of complex
oligosaccharide structures. It is a well documented fact
that carbohydrates, in addition to their well-known role
as a source of energy, are crucial in various biological
processes such as cell–cell recognition, tumor cell
metastasis, and leukocyte adhesion during inflamma-
tion.1,2 However, the molecular basis of many processes
are often still uncertain despite tremendous progress
made in this field. The glycosyltransferases of the Leloir
pathway are key catalysts for the synthesis of oligosac-
charides and glycoconjugates in vivo.3–12 These enzymes
transfer activated monosaccharide units in the form of
their nucleotide mono- or diphosphate derivatives to a
specific free hydroxy group of the acceptor molecule.
Inhibition or modulation of this transfer reaction pro-
vides an excellent opportunity for intervention of the
oligosaccharide biosynthesis and to obtain a more com-
plete understanding of the structure–activity relation-
ship of oligosaccharides on a molecular basis.13
affinity to a(2–6)-sialyltransferase.16 Based upon these
observations, we report herein the synthesis of sugar
mimicking aryl/hetarylmethyl phosphonate UMP
derivatives 1–4 as potential glucosyl- (or eventually
galactosyl-) transferase inhibitors.
O
X
NH
2Na+
Y
-
-
O
O
O
O
N
O
P
P
O
O
O
1 X = OH, Y = CH
2 X = H, Y = CH
3 X = OH, Y = N
4 X = H, Y = N
OH
OH
The required benzyl bromide derivatives 9 and 1017
were prepared from their corresponding methyl precur-
sors 5 and 6, respectively, by treating them with N-
bromo succinimide (NBS) in the presence of catalytic
amounts of dibenzoyl peroxide (DBP) in refluxing car-
bon tetrachloride (Scheme 1). The bromides 9 and 10
on Michaelis–Arbuzov reaction with tris-trimethylsilyl
phosphite in toluene at 95°C for 4 h furnished the
respective bis-trimethylsilylphosphonates 13 and 14 in
quantitative yield (1H NMR). The bis-trimethyl-
silylphosphonates are highly labile to moisture and had
to be stored under argon; they were used in the next
step without further purification. The deprotection of
the TMS groups and subsequent preparation of sodium
Earlier, we had reported14 the synthesis of a transition-
state based analog of galactosyltransferase which exhibi-
ted high inhibitor properties towards galactosyl-
transferases. Encouraged by this, we have recently
reported15 transition-state based analogs of sialyltrans-
ferases which showed very high affinity towards the
enzyme in the nanomolar range. However, the sugar
mimicking aryl analogs of CMP-Neu5Ac turned out to
be potent inhibitors exhibiting very high binding
Keywords: glycosyltransferases; transition-state; inhibitors; synthesis.
* Corresponding author. Tel.: +49-7531-88 2538; fax: +49-7531-88
3135; e-mail: richard.schmidt@uni-konstanz.de
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)00974-1

5394
A. K. Bhattacharya et al. / Tetrahedron Letters 42 (2001) 5393–5395
X
X
X
Y
Y
Y
iv
i or ii or iii
CH2Br
OTMS
OTMS
P
Z
O
5 X = OAc, Y = CH, Z = H
6 X = H, Y = CH, Z = H
7 X = OAc, Y = N, Z = H
8 X = H, Y = N, Z = OH
9 X = OAc, Y = CH
10 X = H, Y = CH
11 X = OAc, Y = N
12 X = H, Y = N
13 X = OAc, Y = CH
14 X = H, Y = CH
15 X = OAc, Y = N
16 X = H, Y = N
v, vi
X
+
Y
2HNEt3
1 X = OH, Y = CH
2 X = H, Y = CH
3 X = OH, Y = N
4 X = H, Y = N
-
vii, viii
O
P
-
O
O
17 X = OH, Y = CH
18 X = H, Y = CH
19 X = OH, Y = N
20 X = H, Y = N
Scheme 1. Reagents and conditions: (i) NBS, cat. DBP, CCl4, reflux, 4 h, 40–45% (for 5 and 6); (ii) NBS, cat. AIBN, CCl4, reflux,
Hg-lamp, 8 h, 45% (for 7); (iii) CBr4, PPh3, NEt3, CH2Cl2, 0°C, 1 h, 42% (for 8); (iv) P(OTMS)3, toluene, 95°C, 3.5–4 h, quant.;
(v) 0.2 M NaOMe/MeOH, 0°C, 30 min, Amberlite IR-120 (H+ form); (vi) Amberlite IR-120 (HNEt3 form), 80–90% (two steps);
+
(vii) UMP-morpholidate, 1H-tetrazole, py, 3 days, rt, RP-18; (viii) Amberlite IR-120 (Na+ form), 42–52%.
assignments of 17, 18 and all intermediates are based
on NMR (1H, 13C and 31P) and MS (EI, FAB or
MALDI) data.
salts were carried out by treating the phosphonates 13
and 14 with sodium methanolate in methanol at 0°C for
30 min, which after usual work up furnished disodium
salts; they were transformed into their corresponding
bis-triethylammonium salts 17 and 18 by ion exchange
Finally, reaction of bis-triethylammonium salts 17 and
18 with uridine-5%-morpholidophosphate as activated
+
(Amberlite IR-120, HNEt3 form). The structural
Table 1. NMR data of 1–4
Hc
1
2
3
4
H-5
H-6
H-1%
H-2%
H-3%
H-4%
H-5%
5.77 (d, J5,6=8.0 Hz)
7.75 (d, J6,5=8.0 Hz)
5.86 (d, J1%,2%=4.9 Hz)
5.78 (d, J5,6=8.1 Hz)
7.78 (d, J6,5=8.1 Hz)
5.85 (d, J1%,2%=4.9 Hz)
5.74 (d, J5,6=7.8 Hz)
7.72 (d, J6,5=7.8 Hz)
5.87 (d, J1%,2%=5.0 Hz)
5.80 (d, J5,6=8.1 Hz)
7.79 (m)
5.82 (d, J1%,2%=4.2 Hz)
4.20 (dd, J2%,3%=J2%,1%=4.9 Hz) 4.21 (dd, J2%,3%=J2%,1%=4.9 Hz) 4.20 (dd, J2%,3%=J2%,1%=5.0 Hz) 4.21 (m)
4.12 (m)
4.12 (m)
3.96 (m, H-5a%), 4.02 (m,
H-5b%)
4.11 (m)
4.11 (m)
3.95 (m, H-5a%), 4.04 (m,
H-5b%)
4.13 (dd, J3%,2%=J3%,4%=4.9 Hz) 4.21 (m)
4.11 (m)
3.98 (m, H-5a%), 4.03 (m,
H-5b%)
4.13 (m)
4.06 (m, H-5a%), 4.13 (m,
H-5b%)
H-1¦
Ar-H
3.10 (d, J=21.4 Hz, 2H)
7.14–7.25 (m, 4H)
3.05 (d, J=21.4 Hz, 2H)
6.99–7.14 (m, 4H)
3.28 (d, J=21.8 Hz, 2H)
7.24 (d, J5¦,6¦=7.6 Hz, H-5¦),
7.30 (d, J7¦,6¦=7.6 Hz, H-7¦),
3.00 (d, J=19.6 Hz, 2H)
7.20 (d, J5¦,6¦=7.7 Hz,
H-5¦), 7.33 (d, J7¦,6¦=7.8
7.67 (dd, J6¦,5¦=J6¦,7¦=7.6 Hz, Hz, H-7¦), 7.79 (m, H-6¦)
H-6¦)
Ar-CH3
Ar-CH2OH
31P
–
2.22 (s, 3H)
–
−10.30 (d, J=27.7 Hz,
P(O)O3), 15.10 (d, J=27.7
Hz, CP(O)O2)
–
2.46 (s, 3H)
4.53 (s, 2H)
4.59 (s, 2H)
–
−9.95 (d, J=27.6 Hz,
P(O)O3), 15.04 (d, J=27.6
Hz, CP(O)O2)
−10.00 (d, J=27.6 Hz,
−9.63 (bd, P(O)O3), 17.14
P(O)O3), 12.20 (d, J=27.6 Hz, (bd, CP(O)O2)
CP(O)O2)

A. K. Bhattacharya et al. / Tetrahedron Letters 42 (2001) 5393–5395
5395
UMP derivative in the presence of 1H-tetrazole18 in
pyridine for 3 days at rt afforded 1 and 2 (Table 1) as
white powders, respectively (after isolation and purifica-
tion by HPLC,19 ion exchange, Amberlite IR-120 (Na+
form) and lyophilisation). The structural assignments of
1 and 2 are based on NMR (1H, 13C and 31P) and MS
(FAB or MALDI) data.
3. Kornfeld, S.; Kornfeld, R. Annu. Rev. Biochem. 1985,
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6. Schaub, C.; Mu¨ller, B.; Schmidt, R. R. Glycoconjugate
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Tetrahedron Lett. 1998, 39, 509–512.
8. Martin, T. J.; Schmidt, R. R. Tetrahedron Lett. 1993,
34, 1765–1768.
9. Schmidt, R. R.; Wegmann, B.; Jung, K.-H. Liebigs
Ann. Chem. 1991, 121–124.
In a similar fashion, synthesis of 3 and 4 were also carried
out (Scheme 1). Treatment of 7 with NBS in the presence
of catalytic amounts of a,a%-azo-isobutyronitrile (AIBN)
in CCl4 and irradiation of the reaction mixture for 8 h
with a Hg-lamp furnished 11, whereas bromide 1220,21
was prepared by treatment of 8 with CBr4/Ph3P/Et3N in
CH2Cl2 at 0°C. Subsequent reactions of bromides 11 and
12 with tris-trimethylsilyl phosphite furnished the corre-
sponding phosphonates 15 and 16 which were trans-
formed into their bis-triethylammonium salts 19 and 20
in the usual way. Their reaction with uridine-5%-morpho-
lidiphosphate in the presence of 1H-tetrazole in pyridine
for 3 days at rt furnished 3 and 4 (Table 1) as white
powders, respectively (after isolation and purification by
HPLC,19 ion exchange, Amberlite IR-120 (Na+ form)
and lyophilisation). The structures of 3 and 4 were
assigned on the basis of NMR (1H, 13C and 31P) and MS
(FAB or MALDI) data.
10. (a) Schmidt, R. R. XIVth Int. Carbohydr. Sympl., PL
8, Stockholm, Aug. 1988; (b) Schmidt, R. R.; Gaden,
H.; Jatzke, H. Tetrahedron Lett. 1990, 31, 327–330; (c)
Schmidt, R. R. In Carbohydrates—Synthetic Methods
and Application in Medicinal Chemistry; Ogura, H.;
Hasegawa, A.; Suami, T., Eds.; Kodoanasha Scientific
Ltd: Tokyo, 1992; pp. 68–88.
11. (a) Palcic, M. M.; Heerze, L. D.; Srivastava, O. P.;
Hindsgaul, O. J. Biol. Chem. 1989, 264, 17174–17181;
(b) Noort, D.; van der Marel, G. A.; van der Gen, A.;
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Pays-Bas 1991, 110, 53–56 and references cited therein.
12. Sun, H.; Yang, J.; Amaral, K. E.; Horenstein, B. A.
Tetrahedron Lett. 2001, 42, 2451–2453 and references
cited therein.
In conclusion, we report on the design and synthesis of
inhibitors 1–4 as mimetics of UDP-Glc (or UDP-Gal).
These novel classes of compounds are presumed to
feature potent inhibition of glucosyltransferases (or
galactosyltransferases) because they are structurally
related to the transition states. Biological evaluations are
currently under investigation and we expect that this will
give us insight into various mechanisms of several
metabolic processes. The biological activity data of
inhibitors 1–4 will be reported in due course.
13. Amann, F.; Schaub, C.; Mu¨ller, B.; Schmidt, R. R.
Chem. Eur. J. 1998, 6, 1106–1115.
14. (a) Frische, K. Ph.D. Dissertation, Universita¨t Kon-
stanz, 1992; (b) Schmidt, R. R.; Frische, K. Bioorg.
Med. Chem. Lett. 1993, 3, 1747–1750; (c) Frische, K.;
Schmidt, R. R. Liebigs Ann. Chem. 1994, 325–329.
15. Schaub, C.; Mu¨ller, B.; Schmidt, R. R. Eur. J. Org.
Chem. 2000, 1745–1758.
16. Mu¨ller, B.; Schaub, C.; Schmidt, R. R. Angew. Chem.,
Int. Ed. 1998, 37, 2893–2897.
Acknowledgements
17. (a) Hunter, W. H.; Edgar, D. E. J. Am. Chem. Soc.
1932, 54, 2025–2026; (b) Shaw, H.; Perlmutter, H. D.;
Gu, C.; Arco, S. D.; Quibuyen, T. O. J. Org. Chem.
1997, 62, 236–237; (c) Venkatachalapathy, C.; Pitchu-
mani, K. Tetrahedron 1997, 53, 2581–2584.
This work was supported by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie.
One of the authors (A.K.B.) is grateful to the Deutscher
Akademischer Austauschdienst (DAAD) for a research
fellowship. We are grateful to Ms. Anke Friemel and Mr.
Klaus Ha¨gele, Fachbereich Chemie, Universita¨t Kon-
stanz, Konstanz for recording NMR (600 MHz) and
FAB-MS, respectively.
18. Wittmann, V.; Wong, C. H. J. Org. Chem. 1997, 62,
2144–2147.
19. HPLC conditions: Shimadzu LC8A preparative pump
and a Rainin Dynamax UV 1 detector at 254 nm;
column used: Eurospher RP-18, 7 mm, 250×16 mm
(Knauer, Germany); mobile phase: 0.05 M triethyl-
ammonium bicarbonate buffer+2–8% acetonitrile.
20. Barnes, R. A.; Fales, H. M. J. Am. Chem. Soc. 1953,
75, 3830–3831.
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