Elucidation of the 2-C-methyl-D-erythritol 4-phosphate pathway for isoprenoid biosynthesis: Straightforward syntheses of enantiopure 1-deoxy-D-xylulose from pentose derivatives

Article abstract of DOI:10.1016/S0040-4039(01)00376-8

Optically pure 1-deoxy-D-xylulose, a key metabolite for feeding experiments in the methylerythritol phosphate pathway for isoprenoid biosynthesis, is conveniently synthesised from 1,2-O-isopropylidene-α-D-xylofuranose or from D-arabinose. This renders lab

Full text of DOI:10.1016/S0040-4039(01)00376-8

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 3065–3067
Elucidation of the 2-C-methyl- -erythritol 4-phosphate pathway
D
for isoprenoid biosynthesis: straightforward syntheses of
enantiopure 1-deoxy- -xylulose from pentose derivatives
D
Jean-Franc¸ois Hoeffler, Catherine Grosdemange-Billiard and Michel Rohmer*
Universite´ Louis Pasteur/CNRS, Institut Le Bel, 4 rue Blaise Pascal, 67070 Strasbourg, France
Received 5 March 2001; accepted 6 March 2001
Abstract—Optically pure 1-deoxy-
for isoprenoid biosynthesis, is conveniently synthesised from 1,2-O-isopropylidene-a-
renders labelling with hydrogen isotopes possible. © 2001 Elsevier Science Ltd. All rights reserved.
D
-xylulose, a key metabolite for feeding experiments in the methylerythritol phosphate pathway
D
-xylofuranose or from -arabinose. This
D
1-Deoxy-
D
-xylulose 5-phosphate is the first C5 inter-
Deuterium-labelled isotopomers of isoprenoid precur-
sors, such as deoxyxylulose or methylerythritol, were
required for the detection of the branching in the
MEP pathway leading in Escherichia coli separately
to IPP and DMAPP from an unknown common
intermediate.2 Therefore, the interest in deoxyxylulose
increased rapidly and several synthetic approaches,
mediate in the mevalonate independent methylery-
thritol phosphate (MEP) pathway for isoprenoid
biosynthesis, occurring in bacteria and plant plastids.1
Although not directly an isoprenoid precursor, the
corresponding free pentulose is easily incorporated
into most isoprenoids synthesised by this pathway.
Unlabelled deoxyxylulose is required for supplementa-
tion of mutants with a disrupted deoxyxylulose phos-
phate synthase gene (dxs), which are used for the
identification of the unknown steps of the pathway.
often based on
ial, were reported during the last
D
-tartrate derivatives as starting mater-
years and
5
proved useful for the synthesis of deuterium-
labelled isotopomers.2a,3 The reported deuterium con-
HO
BnO
O
O
H
O
H
BnO
O
i
ii
OH
H
O
OBn H
OBn H
OH
H
H
O
H
O
H
H
OH
H
1
2
3
iii a, b, c
OH
OBn
OBn
iv
v
2
O
4
O
O
3
5
OH
OBn
OBn
1 CH3 OH
CH3 OH
OMe OH
6
5
4
Scheme 1. Chemical synthesis of 1-deoxy-
BnBr, THF (97%); (ii) 0.25 M HCl, dioxane/water (3:1), 90°C (78%); (iii) (a) NaIO4, dioxane/water (2:1); (b) AgNO3,
D
-xylulose from 1,2-isopropylidene-a-D-xylofuranose: (i) NaH, Bu4NI, 18-crown-6,
dioxane/water (4:1), 2 M KOH; (c) CH2N2, ether (90%); (iv) CH3Li, THF, −100°C (72%); (v) H2, Pd/C, MeOH (98%).
Keywords: 1-deoxy-D-xylulose; methylerythritol phosphate; biosynthesis; isoprenoids; 2-C-methyl-D-erythritol phosphate; terpenoids.
* Corresponding author. Fax: +33 (0)3 90 24 13 45; e-mail: mirohmer@chimie.u-strasbg.fr
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)00376-8

3066
J.-F. Hoeffler et al. / Tetrahedron Letters 42 (2001) 3065–3067
tent was however not always quantitative, or the depro-
tection steps often resulted in significant unexpected
deuterium losses. Only two syntheses of deoxyxylulose
have been described starting from a carbohydrate
derivative.4 In this contribution, two syntheses of enan-
diates was not always necessary) with a 48% overall
2
yield. This approach allows the H or 13C labelling on
the C-1 methyl group, but could not be used to prepare
2
the enantiopure 1-deoxy-
D
-xylulose with H labelling at
C-4 required for the detection of the branching in the
MEP pathway.2 Another synthetic route was therefore
tiopure 1-deoxy-D-xylulose are proposed, including the
possibility of deuterium-labelling at C-1 and/or C-4.
developed, starting from
D-arabinose (Scheme 2).
1-Deoxy-
mercially available 1,2-O-isopropylidene-a-
nose 1, which presents the required configuration of the
two asymmetric carbons of 1-deoxy- -xylulose
(Scheme 1). Benzylation of the two hydroxy groups of
the 1,2-O-isopropylidene-a- -xylofuranose 1 followed
by hydrolysis of the acetonide in acidic conditions
afforded the 3,5-O-dibenzyl- -xylofuranose 3. The free
sugar was successively oxidised with NaIO4 and
AgNO3–KOH to give 2,4-O-dibenzyl- -threo-trihy-
D
-xylulose 6 was easily synthesised from com-
The initial step of this alternative synthesis was the
D
-xylofura-
conversion of arabinose 7 onto its thioacetal.7 Treat-
ment of the arabinose thioacetal
8
with t-
D
6
butyldiphenylsilyl chloride in dimethylformamide in the
presence of imidazole resulted in a highly selective
protection of the primary hydroxy group to afford the
silyl ether 9 in 94% yield. Deprotection of the thioacetal
moiety in 9 by treatment with a mercury(II) derivative
in acetone was followed by the formation of an ace-
tonide in the presence of a catalytic amount of acid to
give the arabinofuranose derivative 10 with only the
C-3 hydroxyl group unprotected.8 The configuration
was inverted at C-3 by Swern oxidation9 to the interme-
diate ketone, followed by highly stereoselective reduc-
tion with sodium borohydride to yield the
xylofuranoside 11.10 The presence of the 1,2-O-iso-
D
D
D
droxybutanoic acid, which was subsequently esterified
with diazomethane.5 Addition of methyllithium to this
ester 4,6 followed by a catalytic hydrogenation over
palladium on charcoal gave 1-deoxy-
D
-xylulose 6.
This synthesis of enantiopure 1-deoxy-
D
-xylulose is
very efficient (seven steps, but the isolation of interme-
CHO
S
S
S
S
TBDPSO
O
HO
H
H
OH
O
H
HO
H
OH
HO
H
iii a,b
ii
i
H
O
H
H
H
H
H
OH
OH
H
OH
H
HO
OH
CH2OH
CH2OH
CH2OTBDPS
7
8
9
10
iv a,b
CH2OTBDPS
H
TBDPSO
vii a,b
O
TBDPSO
TBDPSO
5
O
O
H O
O
H
O
HO
R
OBn OH OH
vii
v
1
OBn O
O
4
OBn
H
2 H
H
H
3
CH2OH
H
R
H
H
R
R
14
13
12
11
viii a,b
CR3
CR3
CH2OH
H
O
O
BnO
R
R = H or D
ix, x
BnO
R
H
HO
R
H
xi
OBn
OBn
OH
CH2OBn
CH2OBn
CH2OH
15
16
6
Scheme 2. Chemical synthesis of 1-deoxy-D-xylulose from D-arabinose: (i) EtSH, HCl (70%); (ii) TBDPSCl, imidazole, DMF, 0°C
(94%); (iii) (a) HgO, HgCl2, acetone; (b) CuSO4, acetone, H+ (84%, two steps); (iv) (a) (COCl)2, DMSO, TEA, CH2Cl2, −78°C
to −35°C; (b) NaBH4 or NaBD4, EtOH (71%, two steps); (v) NaH, Bu4NI, 18-crown-6, BnBr, THF (80%); (vi) 80% AcOH, H2O
(83%); (vii) (a) NaIO4, H2O, MeOH; (b) NaBH4, EtOH (97%, two steps); (viii) (a) NaH, Bu4NI, 18-crown-6, BnBr, THF; (b)
Bu4NF, THF (74%, two steps); (ix) (COCl)2, DMSO, TEA, THF, −78°C to −35°C and CH3MgCl or CD3MgI, −10°C (98%); (x)
(COCl)2, DMSO, TEA, CH2Cl2, −78°C to −35°C (91%); (xi) H2, Pd/C, MeOH (98%).

J.-F. Hoeffler et al. / Tetrahedron Letters 42 (2001) 3065–3067
3067
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We thank Mr. J.-D. Sauer for all NMR measurements.
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