Synthesis of substituted 1-\C\-phenyl-D-tetritols and 1-C-(1H-pyrazol-4-yl) -D-tetritols by ring transformation of 2-formylglycals

Article abstract of DOI:10.1081/CAR-200035732

2-Formylglycals 1a,b reacted with dialkyl 3-oxoglutarates in the presence of base to furnish the 5-[(1R,2R(S),3R)-1,2,4-tris(benzyloxy)-3-hydroxy-butyl]- 2-hydroxy-isophthalic acid dialkyl esters 2a-d. Treatment of 1a,b with hydrazine derivatives afforded the substituted 1,2,4-tri-O-benzyl-1C-(1H-pyrazol-4-yl)-D- tetritols 5a-d. Deprotection of 5a,b was achieved with Pd/H₂ to yield the 1C-(1-methyl-1H-pyrazol-4-yl)-D-tetritols 6a,b. Copyright by Marcel Dekker, Inc.

Full text of DOI:10.1081/CAR-200035732

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Synthesis of Substituted
1‐\C\‐Phenyl‐D‐Tetritols and
1‐C‐(1H‐Pyrazol‐4‐yl)‐D‐tetritols by Ring
Transformation of 2‐Formylglycals
Alina Montero a b , Manfred Michalik c , Holger Feist a , Helmut
Reinke a , Ivo Rudloff a d & Klaus Peseke a
a Fachbereich Chemie, Universität Rostock, D‐18051, Rostock,
Germany
b Centro de Bioactivos Químicos, Universidad Central de Las Villas,
Santa Clara, Cuba
c Leibniz‐Institut für Organische Katalyse, Rostock, Germany
d Oswel Research Products Ltd., Lab 5005 — Medical and Biological
Science Building, University of Southampton‐Boldrewood,
Southampton, UK
Published online: 18 Aug 2006.
To cite this article: Alina Montero , Manfred Michalik , Holger Feist , Helmut Reinke ,
Ivo Rudloff & Klaus Peseke (2004) Synthesis of Substituted 1‐\C\‐Phenyl‐D‐Tetritols and
1‐C‐(1H‐Pyrazol‐4‐yl)‐D‐tetritols by Ring Transformation of 2‐Formylglycals, Journal of Carbohydrate
Chemistry, 23:5, 313-324, DOI: 10.1081/CAR-200035732
To link to this article: http://dx.doi.org/10.1081/CAR-200035732
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JOURNAL OF CARBOHYDRATE CHEMISTRY
Vol. 23, No. 5, pp. 313–324, 2004
Synthesis of Substituted 1-\C\-Phenyl-D-Tetritols
and 1-C-(1H-Pyrazol-4-yl)-D-tetritols by Ring
Transformation of 2-Formylglycals#,‡
Alina Montero,1,2 Manfred Michalik,3 Holger Feist,1 Helmut Reinke,1
Ivo Rudloff,1,4 and Klaus Peseke1,
*
1
¨
Fachbereich Chemie, Universitat Rostock, Rostock, Germany
´
2
Centro de Bioactivos Quımicos, Universidad Central de Las Villas, Santa Clara, Cuba
3Leibniz-Institut fu¨r Organische Katalyse, Rostock, Germany
4Oswel Research Products Ltd., Lab 5005 — Medical and Biological Science Building,
University of Southampton-Boldrewood, Southampton, UK
CONTENTS
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
II. RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . 314
III. EXPERIMENTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
A. General Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
#Dedicated to Professor Dr. Dr. hc. Adolf Zschunke on the occasion of his 65th birthday.
‡Presented at the XXth International Carbohydrate Symposium, Hamburg, Germany, 2000.
*
¨
Correspondence: Klaus Peseke, Fachbereich Chemie, Universitat Rostock, D-18051, Rostock,
Germany; Fax: þ49-381-498-6412; E-mail: klaus.peseke@chemie.uni-rostock.de.
313
DOI: 10.1081/CAR-200035732
0732-8303 (Print); 1532-2327 (Online)
www.dekker.com
Copyright # by Marcel Dekker, Inc.

314
Montero et al.
ABSTRACT
2-Formylglycals 1a,b reacted with dialkyl 3-oxoglutarates in the presence of base to
furnish the 5-[(1R,2R(S),3R)-1,2,4-tris(benzyloxy)-3-hydroxy-butyl]-2-hydroxy-
isophthalic acid dialkyl esters 2a–d. Treatment of 1a,b with hydrazine derivatives
afforded the substituted 1,2,4-tri-O-benzyl-1C-(1H-pyrazol-4-yl)-D-tetritols 5a–d.
Deprotection of 5a,b was achieved with Pd/H2 to yield the 1C-(1-methyl-1H-
pyrazol-4-yl)-D-tetritols 6a,b.
Key Words: Formylglycals; Acyclo–C–nucleosides; Pyrazoles; Isophthalic acid
esters; Ring transformation; Push–pull alkenes.
INTRODUCTION
Owing to their potential biological properties, substantial efforts have been devoted
to the synthesis of modified nucleosides since their discovery.[1–8] In order to obtain
less toxic, less susceptible to viral resistance or more active compounds of this type
new syntheses have been developed. Furthermore, the syntheses of heterocycles with a
polyhydroxyalkyl chain have attracted great interest in synthetic organic chemistry.[9–11]
In earlier studies, we investigated the ring transformations of C-branched, unsat-
urated sugars with push–pull functionalisation to furnish a new class of modified acyclo-
C-nucleosides.[12–15] We describe in this paper the reactions of 2-formylglycals
using 1,3-C,C0- and 1,2-N,N0-dinucleophiles to obtain new acyclo-C-nucleoside analogues.
RESULTS AND DISCUSSION
Because of their push–pull activated carbon–carbon double bond,[16–18] 2-formyl-
glycals 1a,b[19] synthesised by a Vilsmeier–Haack reaction of O-benzyl protected
glycals are a versatile class of compounds, which should allow the nucleophilic attack
of dinucleophiles at C-1 under ring opening of the glycals followed by cyclisation
involving the formyl group. Treatment of 1a,b under reflux with dialkyl 3-oxoglutarates
as 1,3-C,C0-dinucleophiles and potassium carbonate in presence of crown ether afforded
the
expected
5-[(1R,2R(S),3R)-1,2,4-tris(benzyloxy)-3-hydroxy-butyl]-2-hydroxy-
isophthalic acid dialkyl esters 2a–d in such ring transformation reactions (Sch. 1).
The NMR spectra of these compounds showed the absence of signals for the formyl
group and the presence of two hydroxy and alkoxycarbonyl groups. All the other analytical
data are in accordance with the proposed open-chain sugar structures as well. The NMR
signals of the carbon and hydrogen atoms could unambiguously be assigned with 13C,
1H correlation experiments confirming the postulated structures.
Furthermore, an x-ray structure of compound 2d could be obtained. An ORTEP
drawing is shown in Fig. 1.
The crystal structure of 2d is dominated by the formation of hydrogen bridges. The
infinite chains of molecules along the b axis are formed by bridges between the hydroxyl
group at C-3 and one of the carbonyl groups of a neighbouring molecule. The other
hydroxyl group at C-40 is involved in an intramolecular hydrogen bridge towards one of

Ring Transformation of 2-Formylglycals
315
Scheme 1.
the carbonyl groups in the same molecule. This phenomenon helps to explain the complex
infrared spectra of 2d.
In order to obtain benzofuran derivatives, we carried out the reactions of 2c,d
with ethyl chloroacetate in the presence of potassium carbonate in acetone. After a
first step, the 5-[(1R,2R(S),3R)-1,2,4-tris(benzyloxy)-3-hydroxy-butyl]-2-ethoxycarbo-
nylmethoxy-isophthalic acid diethyl esters 3a,b were isolated. However, the desired
heterocyclisation to yield the corresponding 5-[(1R,2R(S),3R)-1,2,4-tris(benzyloxy)-
3-hydroxy-butyl]-3-hydroxy-benzo[b]furan-2,7-dicarboxylic acid diethyl esters could
not be achieved.

316
Montero et al.
Figure 1. ORTEP drawing of 2d.
The push–pull functionality of 1a,b should also allow reactions with 1,2-N,N0-
dinucleophiles. In analogy to similar push–pull compounds,[17–19] the nucleophilic
attack of hydrazine derivatives at C-1 was accompanied by cyclisation involving the
formyl group to furnish the corresponding pyrazole ring. In this manner, treatment of
the starting materials with methylhydrazine and 2-hydrazinoethanol, respectively, under
reflux afforded the substituted (1R)-1,2,4-tri-O-benzyl-1-C-(1H-pyrazol-4-yl)-D-alditols
4a–d. The IR and the 13C NMR spectra of these products showed the absence of
signals for the formyl group. Furthermore, the successful ring transformation was
proven by observing the typical long range coupling between the pyrazol protons
H-30 and H-50 (4J ꢀ 0.6 Hz for 4a,b and 0.9 Hz for 4c,d, respectively) in the 1H NMR spec-
trum due to the W-arrangement. Furthermore, in the 1H NMR spectra of 4c, d appeared an
1
1
1
additional signal for an OH group. 13C, H and H, H correlation spectra allowed the
unambiguous assignment of all signals for the proposed structures. Thus, the distinction
of H-30 and H-50 was possible by a correlation found for H-50 and N–Me in the
NOESY spectrum of 4b.
Finally, we examined the deprotection of the synthesised systems for two examples.
The catalytic hydrogenation[20] of compounds 4a,b was successful and afforded the

Ring Transformation of 2-Formylglycals
317
acyclo-C-nucleoside analogues 5a,b in very good yields. In the 1H NMR of 5a,b spectra
signals for benzyl groups were absent and instead four signals for OH groups were found.
In conclusion, we described here starting from push–pull functionalised unsaturated
sugars a simple method to prepare aryl and hetaryl C-substituted alditoles to be considered
as new acyclo-C-nucleoside analogues.
EXPERIMENTAL
General Procedures
TLC was carried out on silica gel 60 GF254 (Merck) with detection by UV light
(l ¼ 254 nm) and/or by charring with 5% sulfuric acid in methanol. Silica gel 60
(63–200 mesh) (Merck) was used for column chromatography. Melting points were
determined by using a Boetius melting point apparatus and are corrected. Specific
rotations were determined with a Polar LmP (IBZ Messtechnik). IR spectra were recorded
with a Nicolet 205 FT-IR spectrometer. 1H NMR (300.13 and 250.13 MHz, respectively)
and 13C NMR (75.5 and 62.9 MHz, respectively) spectra were recorded on Bruker
instruments ARX 300 and AC 250, respectively, with CDCl3 or DMSO-d6 as solvent.
1
The calibration of spectra was carried out on TMS (internal, H) and solvent (13C)
1
signals (d1H TMS ¼ 0; d13C CDCl3 ¼ 77.0, DMSO-d6 ¼ 39.7). The H and13C NMR
signals were assigned by DEPT and/or two-dimensional 1H, 13C correlation experiments.
The mass spectra were recorded on an AMD 402/3 spectrometer (AMD Intectra GmbH).
Elemental analysis was performed on a Leco CHNS-932 instrument. For chromatography
Merck silica gel 60 (230–400 mesh) was used.
5-[(1R,2R,3R)-1,2,4-Tris(benzyloxy)-3-hydroxy-butyl]-2-hydroxy-isophthalic acid
dimethyl ester (2a). Potassium carbonate (60 mg), 18-crown-6 (50 mg), and dimethyl
3-oxoglutarate (0.043 mL, 0.3 mmol) were added to a solution of 2-formyl-3,4,6-tri-
O-benzyl-D-glucal 1a (100 mg, 0.225 mmol) in THF (5 mL). The mixture was then heated
under reflux and stirred for 6 hr. After this time another amount of dimethyl 3-oxoglutarate
(0.043 mL, 0.3 mmol) was added. The solution was refluxed again and stirring was conti-
nued up to the disappearance of 1a (7 hr, TLC control). After filtration, the solvent was
evaporated and the residue purified by column chromatography (toluene/EtOAc 9 : 1).
Compound 2a was isolated as a colourless syrup. Yield 80 mg (59%); [a]2D3 2 50.3
(c ¼ 1, CHCl3); Rf 0.24 (toluene/EtOAc 9 : 1). IR (film), (cm21): 3446 (OH); 1732,
1
1720, 1678 (C55O); 1613 (C55C). H NMR (300.13 MHz, CDCl3), d 1.92 (br, 1H,
3
3
OH-30); 3.50 (dd, 1H, J1,2 ¼ 3.0 Hz, J2,3 ¼ 7.3 Hz, H-20); 3.52–3.56 (m, AB part of
2
ABX, 2H, H-40a,b); 3.84 (s, 6H, Me); 3.94 (m, 1H, H-30); 3.98 (d, 1H, J ¼ 11.0 Hz,
2
2
CHHPh); 4.17 (d, 1H, J ¼ 11.8 Hz, CHHPh); 4.26 (d, 1H, J ¼ 11.0 Hz, CHHPh); 4.43
2
(s, 2H, CH2Ph); 4.47 (d, 1H, J ¼ 11.8 Hz, CHHPh); 4.61 (d, 1H, H-10); 6.91–6.97
(m, 2H, Ph); 7.07–7.14 (m, 3H, Ph); 7.17–7.30 (m, 10H, Ph); 7.99 (s, 2H, H-4, H-6);
13
11.69 (s, 1H, OH-2). C NMR (75.5 MHz, CDCl3), d 52.3 (Me); 70.1 (C-30); 70.9,
71.3, 73.5, 74.6 (C-40, CH2Ph); 78.7 (C-10); 82.0 (C-20); 116.4 (C-1, C-3); 127.6, 127.8
(p-Ph); 128.0, 128.1, 128.3, 128.4, 128.5 (o-, m-,p-Ph); 129.0 (C-5); 135.6 (C-4, C-6);
137.4 (2x), 137.8 (i-Ph); 161.1 (C-2); 167.9 (C55O). MS (FAB positive, NBA/NaCl),
m/z (%): 623 (100) [M þ Na]þ.
Anal. calcd for C35H36O9(600.65): C, 69.99; H, 6.04. Found: C, 69.96; H, 5.79.

318
Montero et al.
5-[(1R,2S,3R)-1,2,4-Tris(benzyloxy)-3-hydroxy-butyl]-2-hydroxy-isophthalic acid
dimethyl ester (2b). The reaction of 1b with dimethyl 3-oxoglutarate was carried out
as described above for the preparation of 2a. Compound 2b was isolated as a white
solid after recrystallisation from n-heptane. Yield 68 mg (50%); mp 78–818C; [a]D23
229.0 (c ¼ 1, CHCl3); Rf 0.24 (toluene/EtOAc 9 : 1). IR (KBr), n (cm21): 3414 (OH);
1742, 1705, 1682 (C55O); 1610 (C55C). 1H NMR (300.13 MHz, CDCl3), d 2.00
2
3
(br, 1H, OH-30); 3.45 (dd, 1H, J4a,4b ¼ 9.5 Hz, J3,4a ¼ 6.1 Hz, H-40a); 3.51 (dd, 1H,
3J3,4b ¼ 6.1 Hz, H-40b); 3.54 (dd, 1H, J1,2 ¼ 8.1 Hz, J2,3 ¼ 2.2 Hz, H-20); 3.86
3
3
2
(s, 6H, Me); 3.86 (d, 1H, J ¼ 10.8 Hz, CHHPh); 4.10 (dt, 1H, H-30); 4.16 (d, 1H,
2J ¼ 10.8 Hz, CHHPh); 4.21 (d, 1H, J ¼ 11.6 Hz, CHHPh); 4.36 (d, 1H, J ¼ 11.6 Hz,
2
2
2
CHHPh); 4.45 (d, 1H, H-10); 4.43, 4.47 (q(AB), 2H, J ¼ 11.9 Hz, CH2Ph); 6.80–6.88
(m, 2H, Ph); 7.05–7.14 (m, 3H, Ph); 7.15–7.31 (m, 10H, Ph); 7.98 (s, 2H, H-4,
13
H-6); 11.69 (s, 1H, OH-2). C NMR (62.9 MHz, CDCl3), d 52.4 (Me); 69.4 (C-30);
71.0 (CH2Ph); 71.1 (C-40); 73.5, 74.4 (CH2Ph); 79.4 (C-10); 81.1 (C-20); 116.3 (C-1,
C-3); 127.7–128.4 (Ph); 129.7 (C-5); 135.6 (C-4, C-6); 137.0, 137.4, 137.8 (i-Ph);
161.2 (C-2); 167.8 (C55O). MS (FAB positive, NBA/NaCl), m/z (%): 623 (100)
[M þ Na]þ.
Anal. calcd for C35H36O9(600.65): C, 69.99; H, 6.04. Found: C, 70.01; H, 6.16.
5-[(1R,2R,3R)-1,2,4-Tris(benzyloxy)-3-hydroxy-butyl]-2-hydroxy-isophthalic acid
diethyl ester (2c). Diethyl 3-oxoglutarate (0.108 mL, 0.6 mmol) and 2-formyl-3,4,6-tri-
O-benzyl-D-glucal 1a (100 mg, 0.225 mmol) were reacted as described for the preparation
of 1a. Compound 2c was isolated as a colourless syrup. Yield 78 mg (55%); [a]2D4 233.7
(c ¼ 1, CHCl3); Rf 0.29 (toluene/EtOAc 9 : 1). IR (film), n (cm21): 3429 (OH); 1731,
1717, 1672 (C55O); 1612 (C55C). 1H NMR (300.13 MHz, CDCl3), d 1.31 (t, 6H,
3
3
3J ¼ 7.3 Hz, Me); 2.42 (br, 1H, OH-30); 3.49 (dd, 1H, J1,2 ¼ 3.0 Hz, J2,3 ¼ 7.6 Hz,
H-20); 3.52–3.60 (m, AB part of ABX, 2H, H-40a,b); 3.96 (d, 1H, 2J ¼ 11.0 Hz,
2
2
CHHPh); 3.97 (m, 1H, H-3); 4.18 (d, 1H, J ¼ 11.8 Hz, CHHPh); 4.22 (d, 1H, J ¼
2
11.0 Hz, CHHPh); 4.32 (m, 4H, CH2); 4.44 (s, 2H, CH2Ph); 4.48 (d, 1H, J ¼ 11.8 Hz,
CHHPh); 4.63 (d, 1H, H-10); 6.90–6.96 (m, 2H, Ph); 7.06–7.13 (m, 3H, Ph);
7.14–7.31 (m, 10H, Ph); 7.98 (s, 2H, H-4, H-6); 11.76 (s, 1H, OH-2). 13C NMR
(75.5 MHz, CDCl3), d 14.2 (Me); 61.5 (CH2); 70.1 (C-30); 70.9, 71.3, 73.5, 74.7 (C-40,
CH2Ph); 78.6 (C-10); 82.0 (C-20); 116.7 (C-1, C-3); 127.6, 127.9 (p-Ph); 128.0, 128.1,
128.4, 128.4, 128.5 (o-, m-, p-Ph); 128.9 (C-5); 135.2 (C-4, C-6); 137.4, 137.5, 137.8
(i-Ph); 161.2 (C-2); 167.5 (C55O). MS (CI, iso-butane), m/z (%): 629 (0.5) [M þ H]þ,
91 (100).
Anal. calcd for C37H40O9(628.71): C, 70.68; H, 6.41. Found: C, 70.74; H, 6.32.
5-[(1R,2S,3R)-1,2,4-Tris(benzyloxy)-3-hydroxy-butyl]-2-hydroxy-isophthalic acid
diethyl ester (2d). The reaction of 1b with diethyl 3-oxoglutarate was carried out as
described above for the preparation of 2c. Recrystallisation from dichloromethane/
n-heptane yielded 2d as colourless crystals. Yield 76 mg (54%); mp 78–818C;
[a]2D4 2 23.4 (c ¼ 0.5, CHCl3); Rf 0.33 (toluene/EtOAc 9 : 1). IR (KBr), n (cm21):
1
3429 (OH); 1732, 1708, 1665 (C55O); 1612 (C55C). H NMR (250.13 MHz, CDCl3), d
3
2
1.34 (t, 6H, J ¼ 7.3 Hz, Me); 2.53 (br, 1H, OH-30); 3.45 (dd, 1H, J4a,4b ¼ 9.5 Hz,
3J3,4a ¼ 6.1 Hz, H-40a); 3.52 (dd, 1H, J3,4b ¼ 6.1 Hz, H-40b); 3.53 (dd, 1H,
3
3J1,2 ¼ 8.2 Hz, J2,3 ¼ 2.1 Hz, H-20); 3.82 (d, 1H, J ¼ 11.0 Hz, CHHPh); 4.12 (d, 1H,
3
2
2J ¼ 11.0 Hz, CHHPh); 4.14 (br m, 1H, H-30); 4.21 (d, 1H, J ¼ 11.5 Hz, CHHPh);
2
2
4.34 (q, 4H, CH2); 4.36 (d, 1H, J ¼ 11.5 Hz, CHHPh); 4.46 (d, 1H, H-10); 4.45, 4.48

Ring Transformation of 2-Formylglycals
319
(q(AB), 2H, 2J ¼ 11.8 Hz, CH2Ph); 6.80–6.88 (m, 2H, Ph); 7.05–7.14 (m, 3H, Ph); 7.15–
7.30 (m, 10H, Ph); 7.99 (s, 2H, H-20, H-60); 11.82 (s, 1H, OH-40). 13C NMR (62.9 MHz,
CDCl3), d 14.2 (Me); 61.6 (CH2); 69.4 (C-30); 71.0, 71.2, 73.5, 74.4 (C-40, CH2Ph);
79.4 (C-10); 81.1 (C-20); 116.6 (C-1, C-3); 127.7–128.5 (Ph); 129.6 (C-5); 135.3 (C-4,
C-6); 137.0, 137.4, 137.9 (i-Ph); 161.4 (C-2); 167.4 (C55O). MS, (CI, iso-butane), m/z
(%): 629 (0.5) [M þ H]þ.
Anal. calcd for C37H40O9(628.71): C, 70.68; H, 6.41. Found: C, 70.78; H, 6.66.
˚
Compound 2d was subjected to x-ray analysis at 293 K and wavelength 0.71073 A.
The crystal was sealed onto a glass fiber and mounted on a Bruker P4 automated
four circle diffractometer. The structure was solved by direct methods (XS program for
crystal structure solution, version 4.2 for MS-DOS, copyright Bruker Analytical X-ray
Inst. Inc.) and refined by the full-matrix least squares method on F2 (SHELXL-97;
¨
¨
G.M. Sheldrick, Universitat Gottingen, 1997). Non-H atoms were refined with anisotropic
displacement parameters. All hydrogen atoms were placed into theoretical positions and
were refined by using the riding model. 2d, (C37H40O9); formula weight ¼ 628.69;
˚
crystal system: monoclinic; space group: P21; unit cell dimensions: a ¼ 11.781(3) A,
3
˚
˚
˚
b ¼ 10.783(2) A, c ¼ 13.171(2) A, b ¼ 92.58(2)8; volume: 1671.5(6) A ; Z ¼ 2;
density (calculated): 1.249 Mg/m3; absorption coefficient: 0.089 mm21; F(0 0 0) ¼ 668;
crystal size: 0.76 ꢀ 0.63 ꢀ 0.53 mm3; Q range for data collection: 2.270 to 22.008;
index ranges: 212 ꢁ h ꢁ 12, 211 ꢁ k ꢁ 11, 213 ꢁ l ꢁ 13; reflections collected: 4560;
independent reflections: 4075 [R(int) ¼ 0.0489]; completeness to Q ¼ 22.008: 99.8%;
absorption correction: none; data/restraints/parameters: 4075/1/417; goodness-of-fit
on F2: 1.028; final R indices [I . 2s(I)]: R1 ¼ 0.0504, wR2 ¼ 0.1311; R indices (all
data): R1 ¼ 0.0565, wR2 ¼ 0.1377; absolute structure parameter: 0.1(13); largest different
23
˚
peak and hole: 0.187 and 20.161 e A
.
CCDC-190061 contains the supplementary crystallographic data for this paper. These
data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.
html (or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: þ44 1223
336033; E-mail: deposit@ccdc.cam.ac.uk).
5-[(1R,2R,3R)-1,2,4-Tris(benzyloxy)-3-ethoxycarbonylmethoxy-butyl]-2-hydroxy-
isophthalic acid diethyl ester (3a). Ethyl chloroacetate (0.017 mL, 0.159 mmol) and
potassium carbonate (43 mg) were added to a solution of 2c (100 mg, 0.159 mmol) in
acetone (5 mL). The mixture was then heated under reflux and stirring for 5 hr. After
this time, the solution was filtered, the solvent was evaporated, and the residue purified
by column chromatography (toluene/EtOAc 9 : 1). Compound 3a was obtained as a
colourless syrup.
Yield 82 mg (72%); [a]2D1 235.5 (c ¼ 0.4, CHCl3); Rf 0.22 (toluene/EtOAc 5 : 1). IR
(film), n (cm21): 3514 (OH); 1763, 1731 (C55O). 1H NMR (250.13 MHz, CDCl3), d 1.25
(t, 3H, 3J ¼ 7.1 Hz, CH3CH2OC(55O)CH2); 1.28 (t, 6H, 3J ¼ 7.1 Hz, CH3CH2OC(55O));
3
3
1.97 (br, 1H, OH-30); 3.50 (dd, 1H, J1,2 ¼ 2.8 Hz, J2,3 ¼ 7.6 Hz, H-20); 3.55 (m, 2H,
3
H-40a,b); 3.86 (d, 1H, 2J ¼ 10.7 Hz, CHHPh); 3.95 (dt, 1H, J3,4a ¼ 3J3,4b ¼ 4.0 Hz,
2
2
H-30); 4.12 (d, 1H, J ¼ 10.7 Hz, CHHPh); 4.19 (d, 1H, J ¼ 11.6 Hz, CHHPh); 4.24
(q, 2H, CH3CH2OC(55O)CH2); 4.28 (q, 4H, CH3CH2OC(55O)); 4.43 (s, 2H, CH2Ph);
2
4.50 (d, 1H, J ¼ 11.6 Hz, CHHPh); 4.70 (d, 1H, H-10); 4.75 (s, 2H, CH3CH2-
OC(55O)CH2); 6.86–6.96 (m, 2H, Ph); 7.06–7.34 (m, 13H, Ph); 7.94 (s, 2H, H-4,
H-6). 13C NMR (62.9 MHz, CDCl3), d 14.1 (CH3CH2OC(55O)); 14.2 (CH3CH2-
OC(55O)CH2); 61.0 (CH3CH2OC(55O)CH2); 61.5 (CH3CH2OC(55O)); 69.9 (C-30);

320
Montero et al.
70.8, 71.6, 73.5, 74.6 (C-40, CH2Ph); 72.2 (CH3CH2OC(55O)CH2); 78.6 (C-10); 81.8 (C-
20); 127.2 (C-1, C-3); 127.7–128.5 (Ph); 134.0 (C-4, C-6); 135.6 (C-5); 137.2, 137.3,
137.7 (i-Ph); 156.5 (C-2); 165.1 (CH3CH2OC(55O)); 168.7 (CH3CH2OC(55O)CH2).
MS (CI, iso-butane), m/z (%): 715 (3) [M þ H]þ.
HRMS Calcd for C41H46O11–OCH2Ph: 669.26996, Found: 669.26870.
5-[(1R,2S,3R)-1,2,4-Tris(benzyloxy)-3-ethoxycarbonylmethoxy-butyl]-2-hydroxy-
isophthalic acid diethyl ester (3b). The reaction of 3b with chloroacetic acid ethylester
was carried out as described above for the preparation of 3a yielding a colourless syrup.
Yield 78 mg (69%); [a]2D1 219.7 (c ¼ 1, CHCl3); Rf0.25 (toluene/EtOAc 5 : 1). IR (film),
n (cm21): 3514 (OH); 1763, 1731 (C55O). 1H NMR (300.13 MHz, CDCl3), d 1.25 (t, 3H,
3
3J ¼ 7.1 Hz, CH3CH2OC(55O)CH2); 1.29 (t, 6H, J ¼ 7.1 Hz, CH3CH2OC(55O)); 2.22
2
3
(br, 1H, OH-30); 3.42 (dd, 1H, J4a,4b ¼ 9.4 Hz, J3,4a ¼ 6.2 Hz, H-40a); 3.50 (dd, 1H,
3J3,4b ¼ 6.0 Hz, H-40b); 3.53 (dd, 1H, J1,2 ¼ 8.3 Hz, J2,3 ¼ 2.0 Hz, H-20); 2.74 (d, 1H,
3
3
2J ¼ 10.7 Hz, CHHPh); 4.04 (d, 1H, J ¼ 10.7 Hz, CHHPh); 4.10–4.22 (m, 2H, H-30,
2
CHHPh); 4.23 (q, 2H, CH3CH2OC(55O)CH2); 4.29 (q, 4H, CH3CH2OC(55O)); 4.37
2
2
(d, 1H, J ¼ 11.3 Hz, CHHPh); 4.42, 4.47 (q, AB), 2H, J ¼ 11.9 Hz, CH2Ph); 4.54
(d, 1H, H-10); 4.73 (s, 2H, CH3CH2OC(55O)CH2); 6.82–6.86 (m, 2H, Ph); 7.05–
7.30 (m, 13H, Ph); 7.95 (s, 2H, H-4, H-6). 13C NMR (75.5 MHz, CDCl3), d 14.1
(CH3CH2OC(55O)); 14.2 (CH3CH2OC(55O)CH2); 61.0 (CH3CH2OC(55O)CH2); 61.5
(CH3CH2OC(55O)); 69.3 (C-30); 71.1, 71.3, 73.5, 74.4 (C-40, CH2Ph); 72.2 (CH3CH2-
OC(55O)CH2); 79.3 (C-10); 81.1 (C-20); 127.2 (C-1, C-3); 127.7–128.4 (Ph); 134.3 (C-4,
C-6); 136.2 (C-5); 136.9, 137.3, 137.8 (i-Ph); 156.6 (C-2); 165.0 (CH3CH2OC(55O));
168.7 (CH3CH2OC(55O)CH2). MS, (CI, iso-butane), m/z (%): 715 (2) [M þ H]þ.
HRMS calcd for C41H46O11–OCH2Ph: 669.26996, Found: 669.26840.
(1R)-1,2,4-Tri-O-benzyl-1-C-(1-methyl-1H-pyrazol-4-yl)-D-erythritol (4a). A solu-
tion of 1a (100 mg, 0.225 mmol) in ethanol (5 mL) and methylhydrazine (0.024 mL,
0.45 mmol) was 10 min refluxed under stirring. After this time the solvent was evaporated
and the residue purified by column chromatography (toluene/EtOAc 1 : 1). Compound 5a
was isolated as a colourless syrup.
Yield 85 mg (80%); [a]2D3 229.9 (c ¼ 0.5, CHCl3); Rf 0.40 (toluene/EtOAc 1 : 1).
IR (film), n (cm21): 3423 (OH). 1H NMR (300.13 MHz, CDCl3), d 2.76 (br, 1H,
3
OH-3); 3.53–3.62 (m, AB-part of ABX, 2H, H-4a,b); 3.68 (dd, 1H, J1,2 ¼ 4.1 Hz,
2
3J2,3 ¼ 6.7 Hz, H-2); 3.87 (s, 3H, Me); 3.93 (m, 1H, H-3); 4.30 (d, 1H, J ¼ 11.9 Hz,
CHHPh); 4.45 (d, 1H, 2J ¼ 11.3 Hz, CHHPh); 4.50 (s, 2H, CH2Ph); 4.51 (d, 1H,
2J ¼ 11.3 Hz, CHHPh); 4.54 (d, 1H, 2J ¼ 11.9 Hz, CHHPh); 4.67 (d, 1H, H-1);
4
7.16–7.37 (m, 15H, Ph); 7.28 (d, 1H, H-50); 7.47 (d, 1H, J3 ,5 ¼ 0.6 Hz, H-30). 13C
NMR (75.5 MHz, CDCl3), d 38.9 (Me); 70.4 (C-3); 70.7 (CH2Ph); 71.0 (C-4); 73.4,
74.3 (CH2Ph); 73.4 (C-1); 81.4 (C-2); 119.0 (C-40); 127.7, 127.7, 127.8 (p-Ph); 127.9,
128.0, 128.1, 128.3, 128.4, 128.4 (o-, m-Ph); 129.7 (C-50); 137.8, 138.1, 138.1 (i-Ph);
138.6 (C-30). MS, (CI, iso-butane), m/z (%): 473 (27) [M þ H]þ, 91 (100).
Anal. calcd for C29H32N2O4(472.58): C, 73.71; H, 6.82; N, 5.93. Found: C, 73.75;
H, 6.80; N, 5.84.
0
0
1,2,4-Tri-O-benzyl-1C-(1-methyl-1H-pyrazol-4-yl)-D-threitol (4b). The reaction
of 1b with methylhydrazine was carried out as described above for the preparation of
5a. Compound 5b was obtained as a colourless syrup. Yield 94 mg (88%); [a]2D5 251.2
1
(c ¼ 0.45, CHCl3); Rf 0.46 (toluene/EtOAc 1 : 1). IR (film), n (cm21): 3423 (OH). H
3
NMR (300.13 MHz, CDCl3), d 2.32 (br, 1H, OH-3); 3.44 (d, 2H, J3,4 ¼ 5.7 Hz,

Ring Transformation of 2-Formylglycals
321
H-4a,b); 3.63 (dd, 1H, 3J1,2 ¼ 6.4 Hz, 3J2,3 ¼ 3.2 Hz, H-2); 3.79 (s, 3H, Me); 3.96 (dt, 1H,
2
2
H-3); 4.25 (d, 1H, J ¼ 11.6 Hz, CHHPh); 4.32, 3.34 (q(AB), 2H, J ¼ 8.5 Hz, CH2Ph);
2
2
4.41, 4.42 (q(AB), 2H, J ¼ 10.8 Hz, CH2Ph); 4.45 (d, 1H, J ¼ 11.6 Hz, CHHPh); 4.51
(d, 1H, H-1); 7.03–7.07 (m, 2H, Ph); 7.15–7.29 (m, 13H, Ph); 7.23 (d, 1H, H-50); 7.40
(d, 1H, J3 ,5 ¼ 0.6 Hz, H-30). 13C NMR (62.9 MHz, CDCl3), d 38.9 (Me); 69.7 (C-3);
70.5 (CH2Ph); 71.0 (C-4), 73.4, 74.4 (CH2Ph); 73.5 (C-1); 81.3 (C-2); 119.7 (C-40);
127.6, 127.7, 128.1 (p-Ph); 127.8 (2x), 127.9, 128.3, 128.3 (2x) (o-, m-Ph); 129.6 (C-
50); 137.8, 137.9, 138.0 (i-Ph); 138.8 (C-30). MS, (CI, iso-butane), m/z (%): 473 (71)
[M þ H]þ, 91 (100).
4
0
0
Anal. calcd for C29H32N2O4(472.58): C, 73.71; H, 6.82; N, 5.93. Found: C, 73.48;
H, 6.89; N, 5.84.
1,2,4-Tri-O-benzyl-1C-[1-(2-hydroxy-ethyl)-1H-pyrazol-4-yl]-D-erythritol (4c).
A solution of 1a (100 mg, 0.225 mmol) in ethanol (5 mL) and 2-hydrazinoethanol
(0.031 mL, 0.45 mmol) were reacted as described for preparation of 5a. The resulting
residue was purified by column chromatography (chloroform/methanol 9 : 1). Compound
5c was isolated as a colourless syrup.
Yield 101 mg (89%); [a]2D4 29.8 (c ¼ 1, CHCl3); Rf 0.34 (chloroform/methanol
1
9 : 1). IR (film), n (cm21): 3415 (OH). H NMR (250.13 MHz, CDCl3), d 2.78 (br, 2H,
3
3
OH-3, CH2CH2OH); 3.51 (m, 2H, H-4a,b); 3.60 (dd, 1H, J1,2 ¼ 4.0 Hz, J2,3 ¼ 7.0 Hz,
H-2); 3.82–3.91 (m, 3H, H-3, CH2CH2OH); 4.10–4.15 (m, 2H, CH2CH2OH), 4.24
(d, 1H, 2J ¼ 11.9 Hz, CHHPh); 4.36, 4.43 (q(AB), 2H, 2J ¼ 11.3 Hz, CH2Ph); 4.42
2
(s, 2H, CH2Ph); 4.49 (d, 1H, J ¼ 11.9 Hz, CHHPh); 4.62 (d, 1H, H-1); 7.08–7.14
4
(m, 2H, Ph); 7.16–7.30 (m, 13H, Ph); 7.32 (d, 1H, H-50); 7.44 (d, 1H, J3 ,5 ¼ 0.9 Hz,
H-30). 13C NMR (62.9 MHz, CDCl3), d 53.7 (CH2CH2OH); 61.8 (CH2CH2OH); 70.3
(C-3); 70.8, 70.9 (C-4, CH2Ph); 73.2 (C-1); 73.4, 74.2 (CH2Ph); 81.1 (C-2); 118.7
(C-40); 127.7–128.5 (Ph); 129.7 (C-50); 137.6, 137.9, 137.9 (i-Ph); 139.0 (C-30). MS,
(CI, iso-butane), m/z (%): 503 (8) [M þ H]þ, 91 (100).
0
0
Anal. calcd for C30H34N2O5(502.61): C, 71.69; H, 6.82; N, 5.57. Found: C, 71.30;
H, 6.65; N, 5.40.
1,2,4-Tri-O-benzyl-1C-[1-(2-hydroxy-ethyl)-1H-pyrazol-4-yl]-D-threitol (4d).
The reaction of 1b with 2-hydrazinoethanol was carried out as described above for the
preparation of 5c. Compound 5d was obtained as a colourless syrup. Yield 102 mg
(90%); [a]2D2 236.1 (c ¼ 1, CHCl3); Rf0.34 (chloroform/methanol 9 : 1). IR (film),
n (cm21): 3415 (OH). 1H NMR (250.13 MHz, CDCl3), d 2.78 (br, 2H, OH-3,
3
CH2CH2OH); 3.43 (dq, AB-part of ABX, 2H, J4a,4b ¼ 8.6 Hz, H-4a,b); 3.64 (dd,
3
3
1H, J1,2 ¼ 6.5 Hz, J2,3 ¼ 3.2 Hz, H-2); 3.83–3.92 (m, 2H, CH2CH2OH); 3.96
3
(dt, 1H, J3,4a ¼ 3J3,4b ¼ 5.8 Hz, H-3); 4.10–4.15 (m, 2H, CH2CH2OH); 4.27
2
2
(d, 1H, J ¼ 11.6 Hz, CHHPh); 4.30, 4.33 (q(AB), 2H, J ¼ 11.0 Hz, CH2Ph); 4.40,
4.44 (q(AB), 2H, 2J ¼ 12.0 Hz, CH2Ph); 4.45 (d, 1H, 2J ¼ 11.6 Hz, CHHPh); 4.53
(d, 1H, H-1); 7.01–7.07 (m, 2H, Ph); 7.16–7.30 (m, 13H, Ph); 7.32 (d, 1H,
4
J3 ,5 ¼ 0.9 Hz, H-50); 7.46 (d, 1H, H-30). 13C NMR (75.5 MHz, CDCl3), d 53.8
(CH2CH2OH); 61.8 (CH2CH2OH); 69.7 (C-3); 70.6 (CH2Ph); 71.1 (C-4); 73.4
(CH2Ph); 73.5 (C-1); 74.4 (CH2Ph); 81.3 (C-2); 119.6 (C-40); 127.6–128.4 (Ph); 129.8
(C-50); 137.8, 137.9, 137.9 (i-Ph); 139.1 (C-30). MS, (CI, iso-butane), m/z (%): 503 (17)
[M þ H]þ, 91 (100).
0
0
Anal. calcd for C30H34N2O5(502.61): C, 71.69; H, 6.82; N, 5.57. Found: C, 71.30;
H, 6.99; N, 5.58.

322
Montero et al.
1C-(1-Methyl-1H-pyrazol-4-yl)-D-erythritol (5a). A suspension of 5a (300 mg,
0.630 mmol) and palladium over active carbon (10%) in anhydrous ethanol (10 mL)
was stirred under a H2-atmosphere. After 15 hr, the mixture was filtered over diatomite
and then evaporated. Recrystallisation from ethanol yielded 6a as colourless crystals.
Yield 125 mg (98%); mp 183–1878C; [a]2D3 235.5 (c ¼ 0.5, MeOH); Rf 0.26
1
(chloroform/methanol 2 : 1). IR (KBr), n (cm21): 3393, 3314, 3278 (OH). H NMR
2
(250.13 MHz, DMSO), d 3.25–3.50 (m, 3H, H-2, H-3, H-4a); 3.56 (dd, 1H, J4a,4b
¼
10.4 Hz, J ¼ 2.5 Hz, H-4b); 3.76 (s, 3H, Me); 4.25–4.65 (br, 3H, 3x OH); 4.70 (br, 2H,
4
H-1, OH); 7.30 (d, 1H, J3 ,5 ¼ 0.9 Hz, H-30); 7.50 (d, 1H, H-50). 13C NMR (62.9 MHz,
DMSO), d 38.5 (Me); 63.6 (C-4); 65.1 (C-1); 71.7 (C-3); 75.0 (C-2); 124.2 (C-40);
129.0 (C-50); 137.4 (C-30). MS, (CI, iso-butane), m/z (%): 203 (22) [M þ H]þ, 185
(100) [M 2 H2O]þ.
0
0
Anal. calcd for C8H14N2O4(202.21): C, 47.52; H, 6.98; N, 13.85. Found: C, 47.50;
H, 7.02; N, 13.73.
1C-(1-Methyl-1H-pyrazol-4-yl)-D-threitol (5b). The deprotection of 5b was carried
out as described above for the preparation of 6a. Recrystallisation from ethanol yielded 6b
as colourless crystals. Yield 120 mg (94%); mp 53–558C; [a]2D3 2 4.1 (c ¼ 0.5, H2O); Rf
0.26 (chloroform/methanol 2 : 1). IR (KBr), n (cm21): 3564, 3388, 3237 (OH). 1H NMR
(250.13 MHz, DMSO), d 3.25–3.55 (m, 3H, H-2, H-4a,b); 3.72 (m, 1H, H-3); 3.77 (s, 3H,
3
3
Me); 4.16 (d, 1H, J ¼ 7.6 Hz, OH-2/4); 4.26 (d, 1H, J3,OH-3 ¼ 5.8 Hz, OH-3); 4.45
3
3
(dd, 1H, J1,2 ¼ 7.6 Hz, H-1); 4.45 (br, 1H, OH-2/4); 4.97 (d, 1H, J1,OH-1 ¼ 5.6 Hz,
OH-1); 7.29 (d, 1H, J3 ,5 ¼ 0.9 Hz, H-30); 7.48 (d, 1H, H-50). 13C NMR (75.5 MHz,
DMSO), d 38.5 (Me); 63.2 (C-4); 66.1 (C-1); 70.4 (C-3); 73.7 (C-2); 124.8 (C-40);
129.0 (C-50); 137.6 (C-30). MS, (CI, iso-butane), m/z (%): 203 (60) [M þ H]þ, 185
(100) [M 2 H2O]þ.
4
0
0
Anal. calcd for C8H14N2O4(202.21): C, 47.52; H, 6.98; N, 13.85. Found: C, 47.14; H,
6.81; N, 13.67.
ACKNOWLEDGMENTS
The authors thank the Deutsche Forschungsgemeinschaft and the Fonds der
´
´
Chemischen Industrie for financial support and Prof. Dr. J. Fernandez-Beltran and
Dr. R. Baluja for their valuable comments. A. M. is grateful to the Deutscher
Akademischer Austauschdienst for a scholarship.
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Received August 26, 2002
Accepted October 28, 2002