A convenient synthesis of 2-C-methyl-d-erythritol 4-phosphate and isotopomers of its precursor

Article abstract of DOI:10.1016/j.tet.2006.12.078

A new synthetic approach toward 2-C-methyl-d-erythritol 4-phosphate (MEP), a key intermediate in the mevalonate-independent biosynthetic pathway for isoprenoids, and deuterated analogues of its precursor, 2-C-methyl-d-erythritol acetonide, is described. T

Full text of DOI:10.1016/j.tet.2006.12.078

Tetrahedron 63 (2007) 2235–2243
A convenient synthesis of 2-C-methyl-D-erythritol 4-phosphate
and isotopomers of its precursor
*
Alexandros E. Koumbis, Stefanos S. Kotoulas and John K. Gallos
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 541 24, Greece
Received 27 November 2006; revised 21 December 2006; accepted 21 December 2006
Available online 28 December 2006
Abstract—A new synthetic approach toward 2-C-methyl-D-erythritol 4-phosphate (MEP), a key intermediate in the mevalonate-independent
biosynthetic pathway for isoprenoids, and deuterated analogues of its precursor, 2-C-methyl-D-erythritol acetonide, is described. This proce-
dure uses 2-C-methyl-D-erythrose acetonide as starting material and delivers, through a mono-protection strategy, the target compounds in
a short way and in high yield.
Ó 2007 Elsevier Ltd. All rights reserved.
pyruvate anion
1. Introduction
OH
OH
O
i
PiO
H
PiO
Isopentenyl diphosphate (IPP, 5, Scheme 1) and dimethyl-
allyl diphosphate (DMAPP, 6) are the two-isoprenoid univer-
sal precursors.1 It was considered, until lately, that these
compounds are biosynthetically prepared in the cells of all
organisms via the mevalonate (MVA) pathway. However,
recent labeling experiments in the laboratories of Rohmer
et al.2 and Arigoni et al.3 independently revealed an alterna-
tive biosynthetic route to both of them. It is of unique interest
that this newly discovered route, MIP,4 is only present in bac-
teria,5 plant chloroplast,6 and algae metabolism.7 Addition-
ally, MEP (3), a key intermediate of MIP, was identified as
a critical metabolite in the development of Plasmodium
falciparum, the parasite responsible for malaria.8 Conse-
quently, a thorough investigation and exploitation of MIP
could enable the development of new classes of herbicides
and specific drugs against pathogenic microorganisms. In-
deed, during the last decade,9 an extensive research activity
has been realized regarding this field. Nevertheless, the com-
plete elucidation of MIP has not yet been achieved. Whereas,
the initial steps of it are well documented,10 the last ones
are still left to be explored (Scheme 1). The genes responsible
for these last transformations (gcpE and lytB) are already
known,11 but their enzymatic expressions lack identification.
For this reason, each facile preparative method for the known
intermediates of MIP could be highly useful.12
OH
O
CO2
1
2
ii
HO
O
O
O P
O
O
P O
iii
O
PiO
OH OH
3
OH OH
4
???
PPiO
PPiO
5
6
Isoprenoids
Scheme 1. The MIP pathway to isoprenoids. Conditions: (i) DXP synthase
(Pi¼–PO23ꢀ); (ii) MEP synthase; (iii) (1) CDP-ME synthase; (2) CDP-ME
kinase; (3) MECDP synthase.13
been published. There is always, however, a great need for
simple and high yielding sequences, which could lead to
enantiopure 3 and labeled analogues.17
MEP and a plethora of natural products and compounds with
pharmaceutical and biological interest contain a chiral ter-
tiary alcohol moiety. Stereoselective construction of this
quaternary carbon center usually represents a major chal-
lenge in the planned synthetic route.18 A part of our recent
research work focuses on the synthesis of such compounds
starting from inexpensive commercially available asymmet-
ric materials, like carbohydrates.19
A number of synthetic schemes using either asymmetric
dihydroxylation14 or chiral pool approaches,15 along with
a biosynthetic method,16 for the preparation of MEP have
* Corresponding author. Tel.: +30 2310 997839; fax: +30 2310 997679;
e-mail: akoumbis@chem.auth.gr
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.12.078

2236
A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
2. Results and discussion
Having a few grams of diol 8 in our hands,23 we then sought
to investigate a suitable way to obtain phosphate 7. Thus, se-
lective introduction of a protecting group to one of the free
hydroxyls in 8 was our next goal. However, the fact that
both of these hydroxyl groups are primary raises the serious
question of bisubstitution. Moreover, it was assumed that the
4-O-protected regioisomer would be the major product in the
case of mono-protection, taking into account that the 2-C-
methyl group slightly imposes a steric hindrance to the
neighboring hydroxyl of C-1. After solving the problem of
monosubstitution, the expected 4-O-mono-protected deriva-
tive could be used, employing the appropriate manipula-
tions, to complete the synthesis.
In continuation of our previous work, we envisaged the
retrosynthesis of 3, as depicted in Scheme 2. According to
this plan, the desired target could be reached by deprotection
of intermediate 7, which is the 4-O-phosphorylated deriva-
tive of 2-C-methyl-D-erythritol acetonide (8). Obviously,
the latter could be used as the precursor of phosphate 7.
1,4-Diol 8 leads back to the hydroxymethyl lactol 9, which
in turn could be simply prepared from D-arabinose.
(BnO)2(O)PO
OH
HO
OH
3
O
O
O
O
O
To address the issue of monosubstitution, the well-estab-
lished tin-mediated mono-derivatization of vicinal 1,2- or
1,3-diols24 was initially investigated. Although our system
is a 1,4-diol, the formation of a tin-participating seven-mem-
bered ring cannot be excluded. Mono-benzylation of 8 was
achieved according to this method affording 12a and 13a
(Scheme 3) in an excellent combined yield, but without
any significant selectivity (Table 1, entry 1).25 Such a behav-
ior can be attributed to a number of reasons. First, it is not
clear whether the tin-intermediate resulted through an intra-
molecular or an intermolecular fashion. Additionally, the
steric hindrance induced by the methyl group is probably
not significantly powerful to differentiate the two hydroxyls
under these reaction conditions.
7
8
OH
OH
D-arabinose
O
O
9
Scheme 2. Retrosynthetic analysis.
Indeed, lactol 9, which is easily prepared on a multigram
scale from D-arabinose acetonide, and unambiguously has
the correct stereochemistry at the quaternary carbon cen-
ter,20 served as the starting material of our choice (Scheme
3). In order to obtain the D-erythritol acetonide key interme-
diate 8, the C-hydroxymethyl derivative 9 was used to obtain
tosylate 10 initially. Practically, this transformation was
found to be quite intriguing since preliminary experiments
employing different bases and/or higher temperatures
yielded to some extent the bis-tosylated by-products and in
some cases the 20-chloro-derivatives 11. It seems that higher
temperatures favor the nucleophilic displacement of tosyl-
oxy group by chloride. However, pyridine at ambient tem-
perature proved to be more reliable, although the reaction
rate was rather lower. Subsequently, tosylate 10 was left to
react under reflux with a reasonable excess amount of
LiAlH4. This caused the concomitant reduction of the lactol
moiety and the replacement of tosyl group by hydride,21 and
8 was obtained almost quantitatively.22
Table 1. Mono-derivatization of diol 8
Entry
EX
Procedurea
Products (ratio)b
Yield %c
1
2
3
4
5
6
7
BnCl
A
B
B
B
B
C
C
12a/13a (1.1:1)
12b/13b (1:1)
12c/13c (2.6:1)
12a/13a (2.8:1)
12d/13d (2.6:1)
12b/13b (5:1)
12c/13c (>20:1)
97
97
86d
96
89
88
89
TBSCl
TBDPSCl
BnBr
PMBCl
TBSCl
TBDPSCl
a
Conditions were as follows: (A) (1) Bu2SnO, toluene, 110 ꢁC; (2) EX,
TBAI, toluene, 110 ꢁC; (B) (1) NaH, THF, 25 ꢁC; (2) EX, THF, 25 ꢁC;
(C) EX, imidazole, Et3N, CH2Cl2, 25 ꢁC.
Calculated on isolated pure regioisomers unless otherwise mentioned.
Combined yields for both regioisomers.
It was impossible to obtain pure 13c.
b
c
d
TBSO
OAc
O
O
14
v
(from 12b)
O
OH
R
HO
OH
RO
OH
HO
OR
AcO
OTBS
iii
iv
v
+
(from 10)
(from 13b)
O
O
O
O
O
O
O
O
O
O
9 R = OH
10 R = OTs
11 R = Cl
8
12
13
15
i
ii
a R = Bn
b R = TBS
c R = TBDPS
d R = PMB
Scheme 3. Synthesis and mono-protection of diol 8. Reagents and conditions: (i) TsCl, pyridine, 25 ꢁC, 90%; (ii) TsCl, pyridine, 60 ꢁC, 29% of 10 and 54% of
11; (iii) LiAlH4, THF, 60 ꢁC, 98%; (iv) see Table 1; (v) Ac2O, Et3N, CH2Cl2, 0–25 ꢁC, 98% for 14, 97% for 15.

A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
2237
Benzyl ethers 12a and 13a could both be employed in our
synthetic plan, but we were keen to investigate other
approaches deeper as well. The results regarding the tin-
mediated mono-benzylation support the hypothesis that
diol 8 behaves as a rather symmetric system. A method for
mono-silylation of symmetrical diols was known to us
from a previous work.26 When this protocol was applied to
8, using TBSCl as electrophile, the mono-substituted deriv-
ative 12b was obtained along with its regioisomer 13b in
a very good combined yield27 and in a ratio of ca. 1.1:1
(entry 2). The structures of 12b and 13b were assigned by
double resonance 1H NMR experiments and assured28
through their conversion to the corresponding acetates 14
and 15. In order to check the influence of the protective
group bulkiness, TBDPSCl was also employed, applying
the same protocol (entry 3). We were not surprised to find
that both mono-silylated regioisomers, 12c and 13c were
again produced but with a significant preference for the
less hindered one, 12c (ratio of ca. 2.6:1). It was not, how-
ever, possible to separate the minor one (13c) from its
regioisomer using routine column chromatography. The
same procedure was also investigated using BnBr as electro-
phile (entry 4). In this case the easily separable mono-benzyl
regioisomers 12a and 13a were formed again in an excellent
combined yield, and with a better preference for the less hin-
dered one, 13a (ratio of ca. 2.8:1). The difference between
silyl and benzyl mono-protections is probably due to the
fact that the latter is much slower and therefore more selec-
tive. PMBCl was also examined (entry 5) and the expected
regioisomers 12d and 13d were obtained in an almost similar
ratio (ca. 2.6:1) but this reaction required prolonged time to
reach completion and a tedious column chromatography
separation to obtain both regioisomers free from traces of
p-methoxybenzyl alcohol.
18b. In this way both regioisomers for each case were
used. Having successfully addressed the issue of mono-pro-
tection and after performing the required manipulations, the
phosphorylation took place for both advanced intermediates
13a and 13b using standard conditions32 and without inci-
dent. The obtained phosphates 17 and 19 were then sub-
jected to deprotection protocols to obtain 3. Thus, 17 was
smoothly desilylated to give 7. Finally, a previously
described two-step sequence15a was applied to 7 and 19
furnishing enantiopure MEP (3) in good overall yields.33
BnO
OTBS
RO
OTBS
ii
iv
i
v
3
12a
7
O
O
O
O
16
13b R=H
17 R = (BnO)2P(O)
iii
RO
OBn
RO
OBn
v
vi
vii
12b
12c
3
O
O
O
O
18a R = TBS
13a R = H
19 R = (BnO)2P(O)
iii
18b R = TBDPS
Scheme 4. Final steps to MEP (3). Reagents and conditions: (i) TBSCl,
imidazole, CH2Cl2, 25 ꢁC, 98%; (ii) H2, Pd/C, MeOH, 25 ꢁC, 98%; (iii)
(BnO)3P, I2, CH2Cl2, pyridine, ꢀ10–25 ꢁC, 92% for 17, 97% for 19; (iv)
TBAF, AcOH, THF, ꢀ10–25 ꢁC, 96%; (v) (1) H2, Pd/C, MeOH, H2O,
25 ꢁC; (2) MeOH, H2O, 60 ꢁC, 58% from 7, 55% from 19; (vi) NaH,
BnBr, THF, 25 ꢁC, 94% for 18a, 91% for 18b; (vii) TBAF, THF, 25 ꢁC,
100% from 18a, 98% from 18b.
Since new synthetic approaches toward labeled analogues of
3 are always important, we decided to take advantage of
a possible stepwise reduction of tosylate 10 in order to obtain
isotopomers of 8,34 the direct precursor of 3. The solution to
this specific task was to initially reduce the lactol moiety with
application of a standard mild protocol (NaBH4 or NaBD4)
and subsequently remove the tosyloxy group under more
forced conditions (LiAlH4 or LiAlD4). Using the above men-
tioned reducing agents in the appropriate order led to very
good yields through the partially reduced diols 20 and 21,
to 20- and 1-deuterated analogues of 8 (22 and 23), respec-
tively (Scheme 5).35 Obviously, the prepared analogues
could be incorporated into the general synthetic scheme in
order to obtain the corresponding isotopomers of 3.
As a final attempt the mono-silylation of 8 with TBSCl and
TBDPSCl was checked in the presence of imidazole and
a catalytic amount of triethylamine (entries 6 and 7, respec-
tively).29 To our delight, this approach gave even better
results with both electrophiles. Especially in the case of
the TBDPS protection the more hindered regioisomer
(13c) was not practically detectable in the reaction mixture.
The above given results prompted us to check the feasibility
of a direct mono-phosphorylation of 8. However, employing
(BnO)2P(O)Cl30 as electrophile in the tin-mediated protocol
repeatedly led to very complicated reaction mixtures from
which it was impossible to obtain pure samples of phosphate
7 and its regioisomer, though we were able to confirm their
formation by 1H NMR spectroscopy.31 Similarly, the phos-
phorylations of 8 using either NaH or imidazole as base
were proved unreliable having a polymeric mass formed
in the first minutes of reaction. A direct phosphorylation of
8 using (BnO)3P in the presence of iodine32 was also not suc-
cessful since none of the expected phosphates were obtained
even under forced conditions.
X
X
HO
OH
HO
OH
Y
i
ii
OTs
10
O
O
O
O
20 X = H
21 X = D
22 X = H, Y = D
23 X = D, Y = H
Scheme 5. Synthesis of labeled analogues of 8. Reagents and conditions:
(i) NaBH4 (or NaBD4), MeOH, 25 ꢁC, 98% for 20, 96% for 21; (ii) LiAlH4
(or LiAlD4), THF, 60 ꢁC, 90% for 22, 91% for 23.
Next, the mono-protected silyl and benzyl derivatives were
selected for the completion of the synthesis. Applying
a high yielding two-step sequence the benzylated alcohol
12a was used to obtain 13b through 16 (Scheme 4). Analo-
gously, 4-O-silyl protected alcohols 12b and 12c gave 13a
through the corresponding fully protected tetrols 18a and
3. Conclusions
In this article, a convenient short synthesis of enantiopure
MEP, a key intermediate of isoprenoid biosynthesis in bacte-
ria and plants, is described. Practically, it embodies facile
functional group interconversions starting from an easily

2238
A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
accessible chiron, 2-C-hydroxymethyl-D-erythrose aceto-
nide (9). The most efficient route described (through 12c)36
involves seven steps and produces MEP in an over 37%
total yield.37 Additionally, 1- and 20-deuterio isotopomers
of 2-C-methyl-D-erythritol acetonide (8) were easily ob-
tained after the appropriate modifications of the synthetic
plan. Because of its compactness and the ability to scale
up involving multigram quantities, this work represents
a highly attractive scheme for the facile preparation of the
target molecules. Moreover, the well investigated mono-
protections of the 1,4-diol system could be useful in the
future for the regioselective preparation of analogous
compounds.
132.7, 132.1, 130.1, 129.8, 128.0, 127.9, 114.7, 114.5,
102.1, 97.5, 92.2, 86.7, 82.5, 82.0, 72.2, 68.7, 67.9, 67.7,
27.6, 27.5, 27.0, 27.6, 21.6 (2C); HRMS m/z 367.0830
[C15H20O7SNa (M+Na)+ requires 367.0827].
4.1.2. 2-C-Chloro-2,3-O-isopropylidene-D-erythrofura-
nose (11). Alcohol 9 (2.9 g, 15 mmol) was dissolved in
dry pyridine (50 mL) and TsCl (3.8 g, 20 mmol) was added
in portions. The mixture was stirred for 8 h at 60 ꢁC and then
worked-up as described for 10. The residual oil was purified
by column chromatography on silica gel with a mixture of
hexane/EtOAc (6:1 v/v) to give, in the order of elution,
1.7 g of chloride 11 (54%, mixture of a and b anomers in
a ratio of ca. 3:1) and 1.5 g of 10 (29%). Compound 11
(solid): mp 61–62 ꢁC; FTIR (neat film) 3430, 2989, 2940,
2882, 1459, 1431, 1372, 1218, 1155, 1064, 1008, 935, 868,
4. Experimental
4.1. General
834, 740 cmꢀ1 1H NMR for the a anomer (300 MHz,
;
CDCl3) d 5.39 (d, J¼2.4 Hz, 1H), 4.65 (d, J¼3.7 Hz, 1H),
4.15 (dd, J¼10.4, 3.7 Hz, 1H), 3.96 (d, J¼10.4 Hz, 1H), 3.90
and 3.83 (ABq, J¼11.6 Hz, 2H), 3.71 (br s, 1H), 1.50 (s,
All commercially available grade quality reagents were used
without further purification. All solvents were purified by
standard procedures before use. Dry solvents were obtained
by the literature methods and stored over molecular sieves.
All reactions were conducted under a nitrogen atmosphere.
All reactions were monitored on commercially available
pre-coated TLC plates (layer thickness 0.25 mm) of Kiesel-
gel 60 F254. Compounds were visualized by use of a UV
lamp or/and p-anisaldehyde ethanolic solution and warming.
Column chromatography was performed in the usual way
using Merck 60 (40–60 mm) silica gel. NMR spectra were
recorded on a 300 MHz spectrometer (1H: 300 MHz, 13C:
75 MHz) in CDCl3, unless otherwise stated. Chemical shifts
are given in parts per million and J in hertz using solvent or
tetramethylsilane as an internal reference. IR spectra were
recorded on an FTIR instrument as indicated. Mass spectra
were obtained by electro spray technique, positive mode
(ES-MS) or MALDI-FTMS.
1
3H), 1.49 (s, 3H); H NMR for the b anomer (300 MHz,
CDCl3) d 5.07 (d, J¼12.2 Hz, 1H), 4.74 (d, J¼3.1 Hz,
1H), 3.98 (d, J¼11.0 Hz, 1H), 3.85 (ABq, obscured, 2H),
3.63 (dd, J¼11.0, 3.1 Hz, 1H), 2.18 (br s, 1H), 1.57 (s,
3H), 1.48 (s, 3H); 13C NMR (75 MHz, CDCl3) d 114.6,
114.4, 102.1, 97.8, 93.9, 89.0, 83.7, 83.1, 72.4, 68.2, 45.1,
43.7, 27.9, 27.6, 27.1, 26.9; HRMS m/z 231.0402/
233.0373 [C8H13ClO4Na (M+Na)+ requires 231.0400/
233.0371].
4.1.3. 2,3-O-Isopropylidene-2-C-methyl-D-erythritol (8).
Lactol 10 (14 g, 41 mmol) was dissolved in dry THF (1 L)
and LiAlH4 (4.6 g, 121 mmol) was added in portions with
vigorous stirring (about 1 h). The resulting suspension was
stirred for 10 h at reflux, then poured slowly in EtOAc
(1 L), acidified to pH 6 with 10% HCl, and filtered. The fil-
trate was shaken with a saturated sodium hydrogencarbonate
solution (500 mL) for 1 h. The aqueous phase was extracted
with EtOAc (3ꢂ500 mL) and the combined organic ones
were washed with brine (200 mL) and dried (Na2SO4). After
removal of the solvents under reduced pressure the residual
oil was purified by column chromatography on silica gel
with a mixture of hexane/EtOAc (2:1 v/v) to give 7.05 g of
diol 8 (98%) as a solid: mp 95–96 ꢁC (lit.22a 95 ꢁC); [a]2D5
ꢀ26.2 (c 0.4, CHCl3) [lit.15a [a]D25 ꢀ26.0 (c 0.36, CHCl3)];
1H NMR, and 13C NMR spectra were identical with those re-
ported in the literature;15a HRMS m/z 199.0947 [C8H16O4Na
(M+Na)+ requires 199.0946].
4.1.1. 2,3-O-Isopropylidene-2-C-(p-toluenesulfonyloxy-
methyl)-D-erythrofuranose (10). Alcohol 920 (15 g,
79 mmol) was dissolved in dry pyridine (500 mL) and
TsCl (19.6 g, 103 mmol) was added in portions. The mixture
was stirred for two days at room temperature and then
poured in a mixture of CH2Cl2 (1 L) and H2O (500 mL).
The aqueous phase was extracted with CH2Cl2 (2ꢂ300 mL)
and the combined organic phases were washed with semi-
saturated brine (150 mL) and dried (Na2SO4). After removal
of the solvents under reduced pressure (below 45 ꢁC), the re-
sidual oil was purified by column chromatography on silica
gel with a mixture of hexane/EtOAc (4:1 v/v) to give 24.6 g
of tosylates 10 (90%) as an oil (mixture of a and b anomers
in a ratio of ca. 1:1): FTIR (neat film) 3468, 2988, 2940,
4.1.4. General procedure B for the mono-protection
of diol 8. NaH 90% (34 mg, 1.25 mmol) was suspended
in dry THF (5 mL) and a solution of diol 8 (220 mg,
1.25 mmol) in dry THF (10 mL) was added at room temper-
ature. The mixture was stirred vigorously for the indicated
time period, and then a solution of EX (1.25 mmol) in dry
THF (10 mL) was added dropwise. After the starting mate-
rial was consumed the reaction mixture was poured in
Et2O (40 mL). The resulting slurry was washed with a 10%
sodium carbonate solution (20 mL), the aqueous phase was
extracted with EtOAc (50 mL), and the combined organic
phases were dried (Na2SO4). The solvents were removed
under reduced pressure and the residual oil was purified by
column chromatography on silica gel.
1
2876, 1598, 1363, 1190, 1176, 1096, 977 cmꢀ1; H NMR
for the a anomer (300 MHz, CDCl3) d 7.82 (d, J¼8.3 Hz,
2H), 7.35 (d, J¼8.3 Hz, 2H), 5.32 (s, 1H), 4.62 (d,
J¼3.5 Hz, 1H), 4.28 (s, 2H), 4.09 (dd, J¼11.4, 3.5 Hz,
1H), 3.95 (d, J¼11.4 Hz, 1H), 2.45 (s, 3H), 1.44 (s, 3H),
1.34 (s, 3H); 1H NMR for the b anomer (300 MHz,
CDCl3) d 7.80 (d, J¼7.9 Hz, 2H), 7.37 (d, J¼7.9 Hz, 2H),
4.75 (s, 1H), 4.66 (d, J¼3.5 Hz, 1H), 4.17 (d, J¼10.5 Hz,
1H), 4.09 (d, J¼10.5 Hz, 1H), 3.95 (d, J¼11.0 Hz, 1H),
3.55 (dd, J¼11.0, 3.5 Hz, 1H), 2.47 (s, 3H), 1.53 (s, 3H),
1.41 (s, 3H); 13C NMR (75 MHz, CDCl3) d 145.5, 144.9,

A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
2239
4.1.5. General procedure C for the mono-protection of
diol 8. Imidazole (272 mg, 4 mmol) and Et3N (30 mL,
0.2 mmol) were added to a solution of diol 8 (352 mg,
2 mmol) in CH2Cl2 (3 mL) at room temperature. Then, silyl
chloride (2 mmol) was added and the mixture was left
stirring for 72 h. The reaction mixture was diluted with
CH2Cl2 (25 mL), washed with a saturated aqueous ammo-
nium chloride solution (10 mL) and brine (5 mL), and dried
(Na2SO4). The solvent was removed under reduced pressure
and the residue was purified by column chromatography on
silica gel.
4.1.8. 4-O-(t-Butyldimethylsilyl)-2,3-O-isopropylidene-2-
C-methyl-D-erythritol (12b) and 1-O-(t-butyldimethyl-
silyl)-2,3-O-isopropylidene-2-C-methyl-D-erythritol
(13b). Procedure B—Reaction time: 45 min. Column chro-
matography was performed with a mixture of hexane/EtOAc
(25:1 v/v) affording, in the order of elution, 174 mg of
mono-silylated diol 13b (48%) and 178 mg of mono-silyl-
ated diol 12b (49%). Procedure C—Column chromato-
graphy was performed as previously described affording,
85 mg of 13b (15%) and 425 mg of 12b (73%). Compound
12b (oil): [a]2D5 ꢀ19.8 (c 2.3, CHCl3); FTIR (neat film) 3478,
1
2978, 2930, 2857, 1464, 1371, 1254, 1094, 838 cmꢀ1; H
4.1.6. 4-O-Benzyl-2,3-O-isopropylidene-2-C-methyl-D-
erythritol (12a) and 1-O-benzyl-2,3-O-isopropylidene-
2-C-methyl-D-erythritol (13a). Procedure A—Diol 8
(110 mg, 0.62 mmol) was dissolved in dry toluene
(20 mL), DBTO (175 mg, 0.7 mmol) was added and the
resulting suspension was heated for 5 h at reflux in a
Dean–Stark apparatus. After cooling at room temperature,
TBAI (39 mg, 0.12 mmol) and BnCl (0.09 mL, 0.78 mmol)
were added successively and the mixture was refluxed for
12 h. The solvent was removed under reduced pressure and
the residual oil was purified by column chromatography with
a mixture of hexane/EtOAc (8:1 v/v) to give, in the order of
elution, 77 mg of mono-benzylated diol 13a (47%) and
83 mg of mono-benzylated diol 12a (50%). Procedure B—
Reaction time: 24 h. Column chromatography was per-
formed as previously described affording 118 mg of 13a
(25%) and 330 mg 12a (71%). Compound 12a (solid): mp
63–64 ꢁC; [a]D25 ꢀ19.2 (c 1.5, CHCl3); FTIR (neat film)
3460, 2980, 2930, 2881, 1499, 1455, 1380, 1217, 1088,
NMR (300 MHz, CDCl3) d 3.93–3.86 (m, 3H), 3.61 (d,
J¼11.6 Hz, 1H), 3.44 (d, J¼11.6 Hz, 1H), 2.79 (br s, 1H),
1.42 (s, 3H), 1.39 (s, 3H), 1.37 (s, 3H), 0.91 (s, 9H), 0.11
(s, 3H), 0.10 (s, 3H); 13C NMR (75 MHz, CDCl3) d 107.7,
82.3, 82.1, 65.3, 60.9, 28.3, 26.4, 25.7, 22.9, 18.2, ꢀ0.1;
HRMS m/z 313.1810 [C14H30O4SiNa (M+Na)+ requires
313.1811]. Compound 13b (solid): mp 42–43 ꢁC; [a]D25
ꢀ19.0 (c 1.2, CHCl3); FTIR (neat film) 3495, 2985, 2956,
1H NMR (300 MHz, CDCl3) d 3.98 (t, J¼6.4 Hz, 1H),
3.83 (br s, 2H), 3.74 (d, J¼9.8 Hz, 1H), 3.25 (d, J¼9.8 Hz,
1H), 2.98 (br s, 1H), 1.42 (s, 3H), 1.39 (s, 3H), 1.38 (s,
3H), 0.91 (s, 9H), 0.11 (s, 3H), 0.10 (s, 3H); 13C NMR
(75 MHz, CDCl3) d 107.4, 82.4, 81.5, 65.4, 60.9, 28.3,
26.3, 25.7, 23.1, 18.0, ꢀ5.8; HRMS m/z 313.1809
[C14H30O4SiNa (M+Na)+ requires 313.1811].
2932, 2859, 1472, 1371, 1254, 1217, 1096, 839, 777 cmꢀ1
;
4.1.9. 1-O-(t-Butyldimethylsilyl)-2,3-O-isopropylidene-
2-C-methyl-D-erythritol (13b) from 18. Benzyl ether 16
(140 mg, 0.37 mmol) was dissolved in MeOH (5 mL). A cat-
alytic amount of 5% Pd/C was added and the mixture was
hydrogenated with H2 for 4 h at atmospheric pressure. Then,
it was filtered through a short pad of CeliteÒ. Removal of the
solvent under reduced pressure afforded 100 mg of pure
alcohol 13b (93%).
1
1022, 752 cmꢀ1; H NMR (300 MHz, CDCl3) d 7.34–7.27
(m, 5H), 4.61 (d, J¼11.8 Hz, 1H), 4.55 (d, J¼11.8 Hz,
1H), 4.07 (t, J¼5.5 Hz, 1H), 3.73 (dd, J¼10.3, 5.5 Hz,
1H), 3.67 (dd, J¼10.3, 5.5 Hz, 1H), 3.45 (d, J¼6.1 Hz,
2H), 2.34 (br t, J¼6.1 Hz, 1H), 1.46 (s, 3H), 1.41 (s, 3H),
1.33 (s, 3H); 13C NMR (75 MHz, CDCl3) d 137.4, 128.4,
127.8, 127.7, 107.9, 81.9, 81.3, 73.7, 67.5, 65.2, 28.1,
26.5, 22.2; HRMS m/z 289.1416 [C15H22O4Na (M+Na)+
requires 289.1416]. Compound 13a (solid): mp 81–82 ꢁC;
[a]2D5 ꢀ14.6 (c 0.7, CHCl3); FTIR (neat film) 3264, 3174,
2981, 2913, 2862, 1480, 1453, 1356, 1213, 1113, 1038,
4.1.10. 4-O-(t-Butyldiphenylsilyl)-2,3-O-isopropylidene-
2-C-methyl-D-erythritol (12c) and 1-O-(t-butyldiphenyl-
silyl)-2,3-O-isopropylidene-2-C-methyl-D-erythritol
(13c). Procedure B—Reaction time: 24 h. Column chroma-
tography was performed with a mixture of hexane/EtOAc
(15:1 v/v) affording 200 mg of pure mono-silylated diol
12c and 245 mg of a 1:1 mixture of 12c and 13c (combined
yield 86%, ratio of ca. 2.6:1). Procedure C—Column chro-
matography was performed as previously described afford-
ing 740 mg of 12c (89%). Compound 12c (oil): [a]2D5 ꢀ9.9
(c 1.2, CHCl3); FTIR (neat film) 3489, 3072, 3050, 2931,
2858, 1473, 1463, 1428, 1371, 1216, 1113, 999, 823,
1
736 cmꢀ1; H NMR (300 MHz, CDCl3) d 7.36–7.29 (m,
5H), 4.53 (s, 2H), 3.98 (t, J¼6.6 Hz, 1H), 3.84–3.71 (m,
2H), 3.59 (d, J¼8.8 Hz, 1H), 3.19 (d, J¼8.8 Hz, 1H), 2.80
(br s, 1H), 1.42 (s, 3H), 1.37 (br s, 6H); 13C NMR
(75 MHz, CDCl3) d 137.2, 128.5, 128.0, 127.8, 107.7,
82.3, 80.8, 73.9, 72.5, 60.9, 28.3, 26.4, 23.6; HRMS m/z
289.1417 [C15H22O4Na (M+Na)+ requires 289.1416].
4.1.7. 1-O-Benzyl-2,3-O-isopropylidene-2-C-methyl-D-
erythritol (13a) from 18a or 18b. Silyl ether 18a or 18b
(0.53 mmol) was dissolved in dry THF (3 mL) and TBAF
(1 M in THF, 0.6 mL, 0.6 mmol) was added at room temper-
ature. The reaction mixture was stirred for 6 h and then
quenched with the addition of a saturated ammonium chlo-
ride solution (5 mL). It was extracted with EtOAc (2ꢂ
10 mL) and the combined organic phases were washed
with brine (5 mL) and dried (Na2SO4). The solvents were
removed under reduced pressure and the residual oil was
purified by column chromatography on silica gel with a mix-
ture of hexane/EtOAc (5:1 v/v) to give alcohol 13a [140 mg
from 18a (100%) or 138 mg from 18b (98%)].
702 cmꢀ1 1H NMR (300 MHz, CDCl3) d 7.67 (t,
;
J¼12.2 Hz, 4H), 7.47–7.36 (m, 6H), 3.98–3.82 (m, 3H),
3.55 (br s, 2H), 2.41 (br s, 1H), 1.41 (s, 3H), 1.38 (s,
3H), 1.36 (s, 3H), 1.07 (s, 9H); 13C NMR (75 MHz,
CDCl3) d 135.6, 132.7, 130.0, 127.8, 107.9, 82.3, 82.2,
65.3, 61.7, 28.2, 26.8, 26.6, 22.8, 19.2; HRMS m/z
437.2121 [C24H34O4SiNa (M+Na)+ requires 437.2124].
1
Compound 13c: H NMR (300 MHz, CDCl3) d 7.69–7.65
(4H, obscured), 7.47–7.36 (6H, obscured), 4.02 (br t, J¼
5.5 Hz, 1H), 3.98–3.85 (1H, obscured), 3.82 (d, J¼7.3 Hz,
1H), 3.76 (d, J¼9.8 Hz, 1H), 3.24 (d, J¼9.8 Hz, 1H), 2.74
(br s, 1H), 1.34 (s, 3H), 1.30 (s, 3H), 1.26 (s, 3H), 1.08 (s,
9H); 13C NMR (75 MHz, CDCl3) d 135.8, 132.7, 130.0,

2240
A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
127.8, 107.6, 82.9, 81.6, 65.8, 61.3, 28.3, 27.0, 26.4,
23.1, 19.3.
J¼11.6, 1.8 Hz, 1H), 4.08 (dd, J¼11.6, 8.5 Hz, 1H), 4.00
(dd, J¼8.5, 1.8 Hz, 1H), 3.61 (d, J¼9.8 Hz, 1H), 3.27 (d,
J¼9.8 Hz, 1H), 2.08 (s, 3H), 1.41 (s, 3H), 1.37 (s, 3H),
1.32 (s, 3H), 0.88 (s, 9H), 0.05 (s, 3H), 0.04 (s, 3H); 13C
NMR (75 MHz, CDCl3) d 170.8, 108.2, 81.3, 81.2, 65.2,
63.4, 28.4, 26.5, 25.7, 21.9, 20.9, 18.0, ꢀ5.7, ꢀ5.8; HRMS
m/z 355.1918 [C16H32O5SiNa (M+Na)+ requires 355.1917].
4.1.11. 4-O-p-Methoxybenzyl-2,3-O-isopropylidene-2-
C-methyl-D-erythritol (12d) and 1-O-p-methoxybenzyl-
2,3-O-isopropylidene-2-C-methyl-D-erythritol (13d).
Procedure B—Reaction time: 48 h. Column chromato-
graphy was performed with a mixture of hexane/EtOAc
(10:1 v/v) affording, in the order of elution, 90 mg of mono-
benzylated diol 13d (24%) and 235 mg of mono-benzylated
diol 12d (63%). Compound 12d (oil): [a]2D5 ꢀ13.9 (c 1.1,
CHCl3); FTIR (neat film) 3479, 2985, 2934, 2873, 1614,
1586, 1515, 1464, 1372, 1248, 1215, 1091, 1000, 930,
4.1.14. 4-O-Benzyl-1-O-(t-butyldimethylsilyl)-2,3-O-
isopropylidene-2-C-methyl-D-erythritol (16). Alcohol
12a (120 mg, 0.45 mmol) was dissolved in dry CH2Cl2
(2.5 mL). Imidazole (60 mg, 0.9 mmol) and a solution of
TBSCl (81 mg, 0.54 mmol) in dry CH2Cl2 (1 mL) were suc-
cessively added at room temperature. The reaction mixture
was stirred for 12 h, and then poured in a saturated sodium
carbonate solution (5 mL). It was extracted with CH2Cl2
(2ꢂ5 mL), the combined organic phases were washed with
brine (5 mL), and dried (Na2SO4). The solvent was removed
under reduced pressure and the residual oil was purified by
column chromatography on silica gel with a mixture of
hexane/EtOAc (8:1 v/v) to give 162 mg of silyl derivative
16 (94%) as an oil: [a]D25 ꢀ8.4 (c 1.5, CHCl3); FTIR (neat
film) 2984, 2954, 2931, 2857, 1742, 1455, 1371, 1251,
1
850, 820 cmꢀ1; H NMR (300 MHz, CDCl3) d 7.25 (d,
J¼8.0 Hz, 2H), 6.88 (d, J¼8.0 Hz, 2H), 4.55 and 4.50
(ABq, J¼11.6 Hz, 2H), 4.05 (dd, J¼6.1, 4.9 Hz, 1H), 3.80
(s, 3H), 3.67 (dd, J¼5.5, 2.4 Hz, 2H), 3.44 (s, 2H), 2.54
(br s, 1H), 1.45 (s, 3H), 1.39 (s, 3H), 1.32 (s, 3H); 13C
NMR (75 MHz, CDCl3) d 159.4, 130.8, 130.0, 113.9,
108.0, 82.0, 81.3, 73.5, 67.1, 65.3, 55.2, 28.2, 26.5, 22.2;
HRMS m/z 319.1523 [C16H24O5Na (M+Na)+ requires
319.1521]. Compound 13d (oil): [a]2D5 ꢀ10.0 (c 1.0,
CHCl3); FTIR (neat film) 3486, 2985, 2934, 2868, 1613,
1586, 1514, 1457, 1372, 1248, 1216, 1096, 1036, 848,
1096, 838, 778 cmꢀ1
;
1H NMR (300 MHz, CDCl3)
820 cmꢀ1
;
1H NMR (300 MHz, CDCl3) d 7.23 (d,
d 7.26–7.19 (m, 5H), 4.61 (d, J¼12.3 Hz, 1H), 4.42 (d, J¼
12.3 Hz, 1H), 3.96 (dd, J¼8.8, 2.9 Hz, 1H), 3.66 (dd,
J¼9.2, 2.9 Hz, 1H), 3.55–3.47 (m, 2H), 3.08 (d, J¼
10.1 Hz, 1H), 1.34 (s, 3H), 1.30 (s, 3H), 1.18 (s, 3H), 0.73
(s, 9H), ꢀ0.09 (s, 3H), ꢀ0.10 (s, 3H); 13C NMR (75 MHz,
CDCl3) d 138.0, 128.3, 127.8, 127.5, 107.8, 82.5, 81.0,
73.5, 68.6, 65.2, 28.4, 26.4, 25.7, 21.8, 17.9, ꢀ5.9, ꢀ6.0;
HRMS m/z 403.2281 [C21H36O4SiNa (M+Na)+ requires
403.2281].
J¼8.5 Hz, 2H), 6.88 (d, J¼8.5 Hz, 2H), 4.46 (s, 2H), 3.97
(br t, J¼6.7 Hz, 1H), 3.84–3.70 (m, 2H), 3.81 (s, 3H), 3.57
(d, J¼9.2 Hz, 1H), 3.16 (d, J¼9.2 Hz, 1H), 2.86 (br s, 1H),
1.40 (s, 3H), 1.37 (s, 6H); 13C NMR (75 MHz, CDCl3)
d 159.6, 129.6, 129.2, 114.0, 107.7, 82.2, 80.9, 73.5, 72.2,
60.9, 55.3, 28.3, 26.5, 23.8; HRMS m/z 319.1522
[C16H24O5Na (M+Na)+ requires 319.1521].
4.1.12. 1-O-Acetyl-4-O-(t-butyldimethylsilyl)-2,3-O-
isopropylidene-2-C-methyl-D-erythritol (14). Alcohol 12b
(145 mg, 0.5 mmol) and Et3N (0.14 mL, 1 mmol) were dis-
solved in dry CH2Cl2 (2.5 mL) at 0 ꢁC. Ac2O (0.08 mL,
0.8 mmol) was added and the mixture was stirred for 3 h
while warming to room temperature. Then, it was poured
in brine (5 mL) and the aqueous phase was extracted with
CH2Cl2 (2ꢂ5 mL). The combined organic phases were dried
(Na2SO4) and the solvents were removed under reduced
pressure. The sticky residue was purified by column chroma-
tography on silica gel with a mixture of hexane/EtOAc
(5:1 v/v) to give 163 mg of acetate 14 (98%) as an oil:
[a]2D5 ꢀ16.2 (c 2.5, CHCl3); FTIR (neat film) 2985, 2956,
2932, 2885, 2858, 1747, 1464, 1373, 1252, 1217, 1097,
4.1.15. 1-O-(t-Butyldimethylsilyl)-2,3-O-isopropylidene-
2-C-methyl-D-erythritol 4-dibenzyl phosphate (17). A
solution of (BnO)3P38 (550 mg, 1.56 mmol) in dry CH2Cl2
(2 mL) was cooled to ꢀ10 ꢁC and I2 (370 mg, 1.46 mmol)
was added. The mixture was stirred for 5 min at the same
temperature, warmed slowly (1 h) to room temperature
while it was decolorized and re-cooled to 0 ꢁC. Then, a
solution of alcohol 13b (377 mg, 1.3 mmol) and pyridine
(0.35 mL, 4.2 mmol) in dry CH2Cl2 (2 mL) was added drop-
wise and the mixture was stirred for 30 min at the same
temperature. After addition of Et2O (20 mL) the resulting
mixture was successively washed with a 25% sodium hydro-
gencarbonate solution (2ꢂ5 mL) and brine (10 mL). The or-
ganic phase was dried (Na2SO4), the solvents were removed
under reduced pressure, and the residual oil was purified by
column chromatography on silica gel with a mixture of
hexane/EtOAc (5:1 v/v) to give 660 mg of phosphate 17
(92%) as an oil: [a]2D5 +2.5 (c 10.0, CHCl3); FTIR (neat
film) 3437, 2984, 2955, 2931, 2885, 2858, 1498, 1457,
1
839, 778 cmꢀ1; H NMR (300 MHz, CDCl3) d 4.09 (d,
J¼11.0 Hz, 1H), 4.05 (d, J¼11.0 Hz, 1H), 3.95 (dd, J¼
7.1, 5.6 Hz, 1H), 3.86 (d, J¼10.4, 5.6 Hz, 1H), 3.74 (dd,
J¼10.4, 7.1 Hz, 1H), 2.10 (s, 3H), 1.43 (s, 3H), 1.39 (s,
3H), 1.36 (s, 3H), 0.90 (s, 9H), 0.08 (s, 6H); 13C NMR
(75 MHz, CDCl3) d 170.8, 108.3, 82.8, 80.3, 66.4, 60.9,
29.7, 28.0, 26.6, 25.8, 22.7, 21.0, ꢀ5.4, ꢀ5.6; HRMS m/z
355.1915 [C16H32O5SiNa (M+Na)+ requires 355.1917].
1372, 1252, 1216, 1097, 1019, 844, 777, 737, 697 cmꢀ1
;
1H NMR (300 MHz, CDCl3) d 7.34 (br s, 10H), 5.06 (br d,
J¼7.0 Hz, 4H), 4.37–4.31 (m, 1H), 4.19–4.11 (m, 1H),
4.00 (d, J¼9.2 Hz, 1H), 3.54 (d, J¼10.1 Hz, 1H), 3.17 (d,
J¼10.1 Hz, 1H), 1.39 (s, 3H), 1.33 (s, 3H), 1.25 (s, 3H),
0.85 (s, 9H), 0.01 (s, 6H); 13C NMR (75 MHz, CDCl3)
d 135.2 (br), 128.51, 128.45, 128.0, 108.2, 82.2 (d,
4.1.13. 4-O-Acetyl-1-O-(t-butyldimethylsilyl)-2,3-O-
isopropylidene-2-C-methyl-D-erythritol (15). According
to the preceding procedure, alcohol 13b (100 mg,
0.34 mmol), gave 110 mg of acetate 15 (97%) as an oil:
[a]2D5 +9.5 (c 1.0, CHCl3); FTIR (neat film) 2986, 2956,
2932, 2859, 1745, 1472, 1464, 1372, 1238, 1218, 1099,
2
3JCP¼7.0 Hz), 81.1, 69.2 (m), 66.6 (d, JCP¼7.0 Hz), 65.2,
28.4, 26.5, 25.8, 21.9, 18.0, ꢀ5.65, ꢀ5.78; HRMS m/z
1
842, 777 cmꢀ1; H NMR (300 MHz, CDCl3) d 4.52 (dd,
574.2417 [C28H43O7PSiNa (M+Na)+ requires 573.2413].

A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
2241
4.1.16. 2,3-O-Isopropylidene-2-C-methyl-D-erythritol
4-dibenzyl phosphate (7). A solution of silyl ether 19
(100 mg, 0.18 mmol) in dry THF (5 mL) was cooled to
procedure described for 17, alcohol 13a (345 mg,
1.3 mmol) gave 665 mg of phosphate 19 (97%) as an oil:
[a]2D5 +1.1 (c 2.1, CHCl3); FTIR (neat film) 3468, 3028,
2984, 2924, 1497, 1455, 1374, 1281, 1215, 1098, 1016,
ꢀ10 ꢁC and then
a mixture of AcOH (0.14 mL,
1
0.24 mmol) and TBAF (1 M in THF, 0.24 mL, 0.24 mmol)
was added dropwise. The mixture was stirred for 15 min at
the same temperature and then warmed to room temperature
over 3 h. EtOAc (20 mL) was added and a saturated ammo-
nium chloride solution was used to adjust pH to 6. The
organic phase was washed with brine, dried (Na2SO4) and
the solvents were removed under reduced pressure. The re-
sidual oil was purified by column chromatography on silica
gel with a mixture of hexane/EtOAc (3:1 v/v) to give 75 mg
of alcohol 7 (96%) as an oil: 1H NMR and 13C NMR spectra
were identical with those reported in the literature;15a HRMS
m/z 459.1545 [C22H29O7PNa (M+Na)+ requires 459.1549].
887, 737, 697 cmꢀ1; H NMR (300 MHz, CDCl3) d 7.34–
7.30 (m, 10H), 7.28–7.25 (m, 5H), 5.04 (br d, J¼7.9 Hz,
4H), 4.46 (d, J¼12.2 Hz, 1H), 4.41 (d, J¼12.2 Hz, 1H),
4.32–4.25 (m, 1H), 4.16–4.07 (m, 1H), 3.99 (dd, J¼8.6,
3.1 Hz, 1H), 3.36 (d, J¼9.2 Hz, 1H), 3.14 (d, J¼9.2 Hz,
1H), 1.38 (s, 3H), 1.33 (s, 3H), 1.30 (s, 3H); 13C NMR
3
(75 MHz, CDCl3) d 137.8, 135.9 (d, JCP¼7.5 Hz), 128.6,
3
128.5, 128.4, 128.0, 127.7, 127.6, 108.5, 81.9 (d, JCP
¼
2
6.7 Hz), 80.5, 73.4, 72.4, 69.3 (m), 66.1 (d, JCP¼6.7 Hz),
28.2, 26.6, 22.4; HRMS m/z 549.2020 [C29H35O7PNa
(M+Na)+ requires 549.2018].
4.1.20. 2-C-Methyl-D-erythritol 4-phosphoric acid (3).
This compound was prepared according to a known proce-
dure.15a Hydrogenation required slightly longer periods
(22–24 h). Alcohol 7 (70 mg, 0.16 mmol) and the corre-
sponding benzylated derivative 19 (100 mg, 0.19 mmol)
afforded 20 mg (58%) and 21 mg (52%) of 3, respectively,
as an amorphous solid: [a]2D5 +6.2 (c 0.1, H2O) [lit.16 [a]D25
+6.4 (c 0.1, H2O)]; 1H NMR, 13C NMR, and 31P NMR spec-
tra were identical with those reported in the literature.15a
4.1.17. 1-O-Benzyl-4-O-(t-butyldimethylsilyl)-2,3-O-
isopropylidene-2-C-methyl-D-erythritol (18a). NaH 90%
(18 mg, 0.7 mmol) was suspended in dry THF (3 mL) and
a solution of alcohol 12b (165 mg, 0.57 mmol) in dry THF
(2 mL) was added at room temperature. The mixture was
stirred vigorously for 1 h, and then a solution of BnBr
(0.12 mL, 1 mmol) in dry THF (2 mL) was added dropwise.
After 24 h the mixture was poured in Et2O (25 mL). The
organic phase was washed with a 10% sodium carbonate
solution (10 mL), the aqueous one was extracted with EtOAc
(25 mL), and the combined organic phases were dried
(Na2SO4). The solvents were removed under reduced pres-
sure and the residual oil was purified by column chromato-
graphy on silica gel with a mixture of hexane/EtOAc (8:1
v/v) to give 205 mg of benzyl derivative 18a (94%) as an
oil: [a]2D5 ꢀ11.4 (c 3.4, CHCl3); FTIR (neat film) 2984,
1H NMR (300 MHz, CDCl3) d 7.35–7.28 (m, 5H), 4.56
(d, J¼12.2 Hz, 1H), 4.51 (d, J¼12.2 Hz, 1H), 3.91 (t,
J¼5.8 Hz, 1H), 3.86–3.78 (m, 2H), 3.43 (d, J¼9.8 Hz, 1H),
3.33 (d, J¼9.8 Hz, 1H), 1.42 (s, 3H), 1.38 (s, 3H), 1.37 (s,
3H), 0.87 (s, 9H), 0.05 (s, 3H), 0.03 (s, 3H); 13C NMR
(75 MHz, CDCl3) d 138.3, 128.3, 128.1, 127.6, 107.8,
83.5, 81.1, 73.5, 72.8, 61.4, 28.2, 28.2, 26.6, 25.8, 22.8,
18.2, ꢀ5.4, ꢀ5.5; HRMS m/z 403.2282 [C21H36O4SiNa
(M+Na)+ requires 403.2281].
4.1.21. 2,3-O-Isopropylidene-2-C-(p-toluenesulfonyloxy-
methyl)-D-erythritol (20). NaBH4 (26 mg, 0.7 mmol) was
added to a solution of lactol 10 (155 mg, 0.45 mmol) in
MeOH (6 mL). The mixture was stirred for 4 h at room tem-
perature, then H2O was added (30 mL) and AcOH was used
in order to adjust pH to 5. The resulting mixture was ex-
tracted with EtOAc (2ꢂ70 mL) and the combined organic
phases were dried (Na2SO4). After removal of the solvents
under reduced pressure the residual oil was purified by col-
umn chromatography on silica gel with a mixture of hexane/
EtOAc (5:1 v/v) to give 152 mg of diol 20 (98%) as a solid:
mp 55–56 ꢁC; [a]D25 +2.6 (c 1.8, CHCl3); FTIR (neat film)
3435, 2987, 2937, 2886, 1598, 1457, 1360, 1218, 1176,
2955, 2931, 2858, 1472, 1370, 1252, 1095, 847, 777 cmꢀ1
;
1055, 984, 848, 815, 667 cmꢀ1 1H NMR (300 MHz,
;
CDCl3) d 7.80 (d, J¼8.3 Hz, 2H), 7.36 (d, J¼8.3 Hz, 2H),
4.26 (d, J¼10.5 Hz, 1H), 4.11 (d, J¼10.5 Hz, 1H), 4.07 (t,
J¼5.7 Hz, 1H), 3.87 (dd, J¼7.0, 6.2 Hz, 2H), 3.65 (d,
J¼11.9 Hz, 1H), 3.58 (d, J¼11.9 Hz, 1H), 2.90 (br s,
2H), 2.45 (s, 3H), 1.40 (s, 3H), 1.32 (s, 3H); 13C NMR
(75 MHz, CDCl3) d 145.2, 134.8, 129.9, 128.0, 109.1,
81.9, 78.1, 70.4, 61.2, 59.9, 28.1, 26.1, 21.6; HRMS m/z
369.0986 [C15H22O7SNa (M+Na)+ requires 369.0984].
4.1.18. 1-O-Benzyl-4-O-(t-butyldiphenylsilyl)-2,3-O-iso-
propylidene-2-C-methyl-D-erythritol (18b). According to
the preceding procedure, alcohol 12c (200 mg, 0.48 mmol),
gave 220 mg of benzyl derivative 18b (91%) as an oil: [a]D25
ꢀ5.6 (c 0.9, CHCl3); FTIR (neat film) 3071, 2932, 2858,
1590, 1472, 1455, 1428, 1372, 1216, 1112, 1000, 823,
4.1.22. [1-2H]2,3-O-Isopropylidene-2-C-(p-toluenesulfo-
nyloxy-methyl)-D-erythritol (21). According to the preced-
ing procedure but using NaBD4 instead of NaBH4, lactol 10
(155 mg, 0.45 mmol) gave 150 mg of diol 21 (96%) as a
foam: FTIR (neat film) 3436, 2988, 2936, 1598, 1455,
1360, 1218, 1176, 1096, 1062, 991, 836, 667 cmꢀ1; 1H NMR
for the major diastereoisomer (300 MHz, CDCl3) d 7.80 (d,
J¼8.6 Hz, 2H), 7.36 (d, J¼8.6 Hz, 2H), 4.26 (d, J¼11.0 Hz,
1H), 4.10 (d, J¼11.0 Hz, 1H), 4.07 (t, J¼6.1 Hz, 1H), 3.92–
3.81 (m, 2H), 3.62 (br d, J¼4.9 Hz, 1H), 3.10 (br s, 2H), 2.45
(s, 3H), 1.40 (s, 3H), 1.31 (s, 3H); 13C NMR (75 MHz,
CDCl3) d 145.1, 132.5, 129.9, 128.0, 109.0, 81.8, 78.1,
70.4, 60.9 (t, 1JCD¼22.5 Hz), 59.9, 28.1, 26.0, 21.6; HRMS
m/z 370.1045 [C15H21DO7SNa (M+Na)+ requires 370.1046].
1
738, 701 cmꢀ1; H NMR (300 MHz, CDCl3) d 7.71–7.64
(m, 4H), 7.44–7.32 (m, 7H), 7.27–7.20 (m, 4H), 4.45 (d,
J¼12.2 Hz, 1H), 4.40 (d, J¼12.2 Hz, 1H), 3.94 (t,
J¼6.1 Hz, 1H), 3.85 (d, J¼6.1 Hz, 2H), 3.38 (d, J¼9.2 Hz,
1H), 3.27 (d, J¼9.2 Hz, 1H), 1.39 (s, 3H), 1.36 (s, 3H),
1.31 (s, 3H), 1.04 (s, 9H); 13C NMR (75 MHz, CDCl3)
d 138.2, 135.6, 133.3, 129.7, 128.0, 127.8, 127.7, 127.6,
107.9, 83.4, 81.1, 73.4, 72.7, 62.2, 28.2, 26.8, 22.7, 19.3,
19.2; HRMS m/z 527.2597 [C31H40O4SiNa (M+Na)+ re-
quires 527.2594].
4.1.19. 1-O-Benzyl-2,3-O-isopropylidene-2-C-methyl-
D-erythritol 4-dibenzyl phosphate (19). According to the

2242
A. E. Koumbis et al. / Tetrahedron 63 (2007) 2235–2243
4.1.23. [20-2H]2,3-O-Isopropylidene-2-C-methyl-D-eryth-
ritol (22). Tosylate 20 (145 mg, 0.42 mmol) was dissolved
in dry THF (10 mL) and LiAlD4 (55 mg, 1.3 mmol) was
added in portions with vigorous stirring (about 1 h). The re-
sulting suspension was stirred for 10 h at reflux, then poured
slowly in EtOAc (30 mL), acidified to pH 5 with 10% HCl,
and filtered. The filtrate was shaken with a saturated sodium
hydrogencarbonate solution (7 mL). The aqueous phase was
extracted with EtOAc (3ꢂ30 mL) and the combined organic
ones were washed with brine (5 mL) and dried (Na2SO4).
After removal of the solvents under reduced pressure the re-
sidual oil was purified by column chromatography on silica
gel with a mixture of hexane/EtOAc (3:1 v/v) to give 67 mg
of deuterated diol 22 (90%) as a foam: [a]2D5 ꢀ13.8 (c 0.9,
CHCl3); FTIR (neat film) 3245, 2987, 2947, 2875, 1460,
7. Schwender, J.; Seeman, M.; Lichtenthaler, H. K.; Rohmer, M.
Biochem. J. 1996, 316, 73–80.
8. Jomaa, H.; Wiesner, J.; Sanderbrand, S.; Altincicek, B.;
Weidemeyer, C.; Hintz, M.; Turbachova, I.; Eberl, M.;
Zeidler, J.; Lichtenthaler, H. K.; Soldati, D.; Beck, E. Science
1999, 285, 1573–1576.
9. Selected recent publications: (a) Rohmer, M. Prog. Drug
Res. 1998, 50, 135–154; (b) Rohmer, M. Nat. Prod. Rep.
1999, 16, 565–574; (c) Rohmer, M. Comprehensive Natural
Products Chemistry. Isoprenoids Including Carotenoids and
Steroids; Cane, D. E., Ed.; Elsevier: Amsterdam, 1999;
Vol. 2, pp 45–67; (d) Rohmer, M. Pure Appl. Chem. 1999,
71, 2279–2284; (e) Lichtenthaler, H. K. Biochem. Soc. Trans.
2000, 28, 785–789; (f) Lichtenthaler, H. K.; Zeidler, J.;
Schwender, J.; Muller, C. Z. Naturforsch., C: Biosci. 2000,
55, 305–313; (g) Zeidler, J.; Schwender, J.; Mueller, C.;
Lichtenthaler, H. K. Biochem. Soc. Trans. 2000, 28, 796–798;
(h) Rohdich, F.; Kis, K.; Bacher, A.; Eisenreich, W. Curr.
Opin. Chem. Biol. 2001, 5, 535–540; (i) Sponsel, V. M.
J. Plant Growth Regul. 2001, 20, 332–345; (j) Dewick, P. M.
Nat. Prod. Rep. 2002, 19, 181–222; (k) Dubey, V. S. Curr.
Sci. 2002, 83, 685–688; (l) Kasahara, H.; Hanada, A.;
Kuzuyama, T.; Takagi, M.; Kamiya, Y.; Yamaguchi, S.
J. Biol. Chem. 2002, 277, 45188–45194; (m) Hoeffler, J.-F.;
Tritsch, D.; Grosdemange-Billiard, C.; Rohmer, M. Eur. J.
Biochem. 2002, 269, 4446–4457; (n) Kuzuyama, T.; Seto, H.
Nat. Prod. Rep. 2003, 20, 171–183; (o) Gao, W.; Raschke,
M.; Alpermann, H.; Zenk, M. H. Helv. Chim. Acta 2003, 86,
3568–3577; (p) Cassera, M. B.; Gozzo, F. C.; D’Alexandri,
F. L.; Merino, E. F.; del Portillo, H. A.; Peres, V. J.; Almeida,
I. C.; Eberlin, M. N.; Wunderlich, G.; Wiesner, J.; Jomaa, H.;
Kimura, E. A.; Katzin, A. M. J. Mol. Biol. 2004, 279, 51749–
51759; (q) Lherbet, C.; Pojer, F.; Richard, S. B.; Noel, J. P.;
Poulter, C. D. Biochemistry 2006, 45, 3548–3553.
10. (a) Takahashi, S.; Kuzuyama, T.; Watanabe, H.; Seto, H.
Proc. Natl. Acad. Sci. U.S.A. 1998, 95, 9879–9884; (b)
Rohdich, F.; Wungsintaweekul, J.; Fellermeier, M.; Sagner,
S.; Herz, S.; Kis, K.; Eisenreich, W.; Bacher, A.; Zenk,
M. H. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 11758–
11763; (c) Kuzuyama, T.; Takagi, M.; Kaneda, K.; Dairi,
T.; Seto, H. Tetrahedron Lett. 2000, 41, 703–706; (d) Herz,
S.; Wungsintaweekul, J.; Schuhr, C. A.; Hecht, S.; Luttgen,
H.; Sagner, S.; Fellermeier, M.; Eisenreich, W.; Zenk,
M. H.; Bacher, A.; Rohdich, F. Proc. Natl. Acad. Sci.
U.S.A. 2000, 97, 2426–2490; (e) Takagi, M.; Kuzuyama, T.;
Kaneda, K.; Watanabe, H.; Dairi, T.; Seto, H. Tetrahedron
Lett. 2000, 41, 3395–3398.
1
1369, 1215, 1180, 1094, 1050, 1030, 931, 862 cmꢀ1; H
NMR (300 MHz, CDCl3) d 3.96 (t, J¼5.0 Hz, 1H), 3.89–
3.86 (m, 2H), 3.61 (d, J¼11.0 Hz, 1H), 3.41 (d, J¼
11.0 Hz, 1H), 3.01 (br s, 2H), 1.45 (s, 3H), 1.40 (s, 3H),
1.35 (t, J¼1.8 Hz, 2H); 13C NMR (75 MHz, CDCl3) d 107.8,
1
82.5, 81.6, 65.2, 60.1, 28.2, 26.5, 22.3 (t, JCD¼19.1 Hz);
HRMS m/z 200.1007 [C8H15DO4Na (M+Na)+ requires
200.1008].
4.1.24. [1-2H]2,3-O-Isopropylidene-2-C-methyl-D-
erythritol (23). According to the preceding procedure but
using LiAlH4 instead of LiAlD4, tosylate 21 (120 mg,
0.35 mmol) gave 56 mg of deuterated diol 23 (91%) as
a foam: FTIR (neat film) 3247, 2986, 2929, 2874, 1448,
1
1369, 1218, 1191, 1105, 1035, 932, 872 cmꢀ1; H NMR
for the major diastereoisomer (300 MHz, CDCl3) d 3.96
(t, J¼4.9 Hz, 1H), 3.89–3.85 (m, 2H), 3.59 (br s, 1H),
2.73 (br s, 2H), 1.45 (s, 3H), 1.40 (s, 3H), 1.37 (s, 3H);
13C NMR (75 MHz, CDCl3) d 107.8, 82.5, 81.6, 64.9 (t,
1JCD¼18.0 Hz), 60.1, 28.2, 26.6, 22.5; HRMS m/z
200.1007 [C8H15DO4Na (M+Na)+ requires 200.1008].
References and notes
1. Qureshi, N.; Porter, J. W. Biosynthesis of Isoprenoid
Compounds; Porter, J. W., Spurgeon, S. L., Eds.; Wiley: New
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3. (a) Arigoni, D.; Eisenreich, W.; Latzel, C.; Sagner, S.;
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cited therein.
4. Mevalonate-independent pathway. It is also called the deoxy-
xylulose-phosphate pathway (named after the first compound
on-route, DXP, 2) or the methylerythritol-phosphate pathway
(named after the first discovered intermediate, MEP, 3).
5. (a) Flesch, G.; Rohmer, M. Eur. J. Biochem. 1988, 175, 405–
411; (b) Rohmer, M.; Sutter, B.; Sahm, H. J. Chem. Soc.,
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13. DXP¼1-D-deoxyxylulose-5-phosphate; CDP-ME¼4-diphos-
phocytidyl-2-C-methyl-D-erythritol; MECDP¼2-C-methyl-D-
erythritol 2,4-cyclodiphosphate.
6. (a) Eisenreich, W.; Menhard, B.; Hylands, P. J.; Zenk, M. H.;
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nance 1H NMR experiments.
15. (a) Kis, K.; Wungsintaweekul, J.; Eisenreich, W.; Zenk, M. H.;
Bacher, A. J. Org. Chem. 2000, 65, 587–592; (b) Hoeffler, J.-F.;
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27. The two isomers were easily separable by column chromato-
graphy.
17. For a previously synthesized labeled analogue of 3, see: Hecht,
S.; Wungsintaweekul, J.; Rohdich, F.; Kis, K.; Radykewicz, T.;
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7770–7775.
28. In each case, substantial deshielding caused by the introduced
acetyl group made it easier to assign its position with double
resonance 1H NMR experiments.
29. The addition of triethylamine significantly accelerates the rate
of reaction.
ꢀ
18. (a) Ramon, D. J.; Yus, M. Curr. Org. Chem. 2004, 8, 149–183;
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30. (a) Wagner, D.; Verheyden, J. P. H.; Moffat, J. G. J. Org. Chem.
1974, 39, 24–30; (b) Manning, D. D.; Bertozzi, C. R.; Rosen,
S. D.; Kiessling, L. L. Tetrahedron Lett. 1996, 37, 1953–1956.
31. The best combined yields were less than 10–15%.
32. Stowell, J. K.; Widlanski, T. S. Tetrahedron Lett. 1995, 36,
1825–1826.
33. MEP (3) was found to have identical physical and spectro-
scopic data with those reported in Ref. 15a.
34. For some already synthesized isotopomers of 2-C-methyl-
19. (a) Gallos, J. K.; Damianou, K. C.; Dellios, C. C.
Tetrahedron Lett. 2001, 42, 5769–5771; (b) Koumbis,
A. E.; Dieti, K. M.; Vikentiou, M. G.; Gallos, J. K.
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ꢀ
erythritol, see: (a) Duvold, T.; Calı, P.; Bravo, J.-M.; Rohmer,
20. (a) Thompson, D. K.; Hubert, C. N.; Wightman, R. H.
Tetrahedron 1993, 49, 3827–3840; (b) Zhao, S.; Petrus, L.;
Serianni, A. S. Org. Lett. 2001, 3, 3819–3822; (c) Ref. 19c.
21. Paquette, L. A.; Fischer, J. W.; Browne, A. R.; Doecke, C. W.
J. Am. Chem. Soc. 1985, 107, 686–691.
22. Diol 8 was found to have identical physical and spectroscopic
data with those reported in: (a) Anthonsen, T.; Hagen, S.;
Sallam, M. A. E. Phytochemistry 1980, 19, 2375–2377; (b)
Ref. 15a.
M. Tetrahedron Lett. 1997, 38, 6181–6184; (b) Charon, L.;
Hoeffler, J. F.; Pale-Grosdemange, C.; Rohmer, M. Tetrahedron
Lett. 1999, 40, 8369–8373.
35. Compounds 21 and 23 are mixtures of diastereoisomers.
36. As it is obvious from Scheme 4, the TBS and benzyl mono-
protected precursors could be equally easily used to obtain 3.
37. To the best of our knowledge this is the highest overall yield
reported so far for the preparation of MEP.
38. Gefflaut, T.; Lemaire, M.; Valentin, M.-L.; Bolte, J. J. Org.
Chem. 1997, 62, 5920–5922.
23. Diol 8 is easily obtained on a 10 g scale reaction sequence.