Total synthesis of a protected form of 2,6-anhydro-5-azido-3,5-dideoxy-2-C-hydroxymethyl-L-allo-heptose; a potential precursor of analogs of C-glycosides of neuraminic acid

Article abstract of DOI:10.1016/S0957-4166(00)00460-2

The title aldehyde (-)-3 and its enantiomer (+)-3 have been prepared starting from furfuryl alcohol and acetone. The method involves the diastereoselective [4+3]-cycloaddition of 2-[(benzyloxy)methyl]furan and 1,3-dibromo-2-oxyallyl cation giving adduct (±)-4 that was converted with high yield into (±)-(2RS,5RS,6SR)-5-azido-2-[(benzyloxy)methyl]-2,3,5,6-tetrahydro- 2,6-bis(hydroxymethyl)-4H-pyran-4-one ((±)-9). Ketone (±)-9 was then transformed with high selectivity into (±)-(2RS,4RS,5SR,6RS)-5-azido-2-[(benzyloxy)methyl]-2,3,5,6- tetrahydro-4-[(triethylsilyl)oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H- pyran-2-methanol (±)-3 that was resolved by the Alexakis-Mangeney method (column chromatography of aminals derived from (1R,2R)-1,2-diphenylethylenediamine). The absolute configuration of (-)-3 was established by circular dichroism and the Dale-Mosher method on derivatives.

Full text of DOI:10.1016/S0957-4166(00)00460-2

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 11 (2000) 4661–4680
Total synthesis of a protected form of
2,6-anhydro-5-azido-3,5-dideoxy-2-C-hydroxymethyl-
L-allo-
heptose; a potential precursor of analogs of C-glycosides of
neuraminic acid
Fre´de´ric Carrel and Pierre Vogel*
Section de chimie de l’Universite´ de Lausanne, BCH, CH 1015 Lausanne-Dorigny, Switzerland
Received 3 October 2000; accepted 16 November 2000
Abstract
The title aldehyde (−)-3 and its enantiomer (+)-3 have been prepared starting from furfuryl alcohol and
acetone. The method involves the diastereoselective [4+3]-cycloaddition of 2-[(benzyloxy)methyl]furan and
1,3-dibromo-2-oxyallyl cation giving adduct ( )-4 that was converted with high yield into ( )-
(2RS,5RS,6SR)-5-azido-2-[(benzyloxy)methyl]-2,3,5,6-tetrahydro-2,6-bis(hydroxymethyl)-4H-pyran-4-one
(( )-9). Ketone ( )-9 was then transformed with high selectivity into ( )-(2RS,4RS,5SR,6RS)-5-azido-2-
[(benzyloxy)methyl]-2,3,5,6-tetrahydro-4-[(triethylsilyl)oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-
methanol ( )-3 that was resolved by the Alexakis–Mangeney method (column chromatography of aminals
derived from (1R,2R)-1,2-diphenylethylenediamine). The absolute configuration of (−)-3 was established
by circular dichroism and the Dale–Mosher method on derivatives. © 2001 Elsevier Science Ltd. All
rights reserved.
1. Introduction
Sialic acid containing glycoconjugates are cell-type specific markers that play vital roles in a
great number of physiologically and pathologically important processes. These include embryo-
genesis, organ development, immune defense, migration and selection of leukocytes, metastasis
of cancer cells, as well as inflammation and the infection by pathogens.1 For instance, the
influenza infection is an example of cell/virus interaction mediated by sialic acid. Virus-releasing
enzyme influenza sialidase inhibitors have been used as drugs against the common flu.2
Inhibitors of sialidases and of sialyltransferases are quite often sialic acid analogs.3,4 A new class
of potential inhibitors are C-glycosides of neuraminic acid and analogs.5 Disaccharides and
* Corresponding author. Tel: 0041 21 692 39 71; fax: 0041 21 692 39 75; e-mail: pierre.vogel@ico.unil.ch
0957-4166/00/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(00)00460-2

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F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
oligosaccharides6 have limited applications as therapeutic agents because of their susceptibility
to enzymatic hydrolysis by glycosidases. One strategy towards by-passing this problem is to
replace the glycosidic oxygen atom with a sulfur7 or by a carbon linker.8 Our laboratory has
proposed recently general approaches to the construction of libraries of C(1“3),9 C(1“2) and
C(1“4)-linked disaccharides10 by condensation of sugar-derived carbaldehydes with bicyclic
enolates or enol triflates. In a preliminary communication,11 we presented the conversion of
2-[(benzyloxy)methyl]furan 1 into a protected form of racemic 3,5-dibromo-3,4,5,6-tetrahydro-4-
hydroxy-2,6-bis(hydroxymethyl)-2H-pyran-2-carboxaldehyde 2 that could be used to carry out
cross-aldolizations, opening an approach to the synthesis of C-disaccharide analogs mimicking
sialic acid glycosides. We report here the preparation the enantiomerically enriched (>98% ee)
2,6-anhydro-5-azido-3,5-dideoxy-2-C-hydroxymethyl- -allo-heptose derivatives (−)-3 also start-
L
ing from 1. Orthogonal protection of the alcoholic moieties in (−)-3 leaves open the possibility
of oxidizing the 2-C-hydroxymethyl group into a carboxylic acid, to prolong the carbon chain
at C-7 and to invert center C-4 in order to approach neuraminic acid structure.
2. Results and discussion
Applying the method of Mann,12 we found that furan 1 (obtained by benzylation13 of furfuryl
alcohol) undergoes smooth [4+3]-cycloaddition with the 1,3-dibromo-2-oxyallyl cation generated
from 1,1,3,3-tetrabromopropan-2-one14 in the presence of Et2Zn giving adduct ( )-4 in 63%
yield, the endo relative configuration of the 2- and 4-bromo substituents being established by the
1H NMR spectrum (3J(H,H), 2D-NOESY). Using the Luche procedure,15 ketone ( )-4 was
reduced into endo-alcohol ( )-5 quantitatively. This alcohol was protected as its MOM ether
( )-6 (89%, two steps). Ozonolysis of the alkene moiety of ( )-6, followed by reductive work-up
(Me2S, then NaBH4), provided the 3,4,5,6-tetrahydro-2H-pyran derivative ( )-7 nearly quantita-
tively. Treatment of ( )-7 with NaN3 (5 equiv.) or tetramethylguanidinium azide16 displaced the
less sterically hindered bromide at C-517 concomitantly with HBr elimination between C-3 and
C-4 giving the azido-enol ether ( )-8 quantitatively. The displacement reaction occurred with
complete inversion as demonstrated with the structure of ( )-8. The latter was established by its
1
spectral data, including its H NMR spectrum (3J(Haxial-5,Haxial-6)=9.1 Hz, 2D-NOESY).
Acidic hydrolysis18 of ( )-8 liberated ketone ( )-9. Selective monosilylation of the less sterically
hindered primary alcohol at C-7 was accomplished using 1.1 equiv. of triisopropylsilyl chloride
and imidazole.19 This furnished ( )-10 in 54% yield based on ( )-6. Acetylation of ( )-10 gave
( )-11 (100%). The ketone ( )-11 was reduced with NaBH4 in methanol giving a 14.4:1 mixture
of alcohols ( )-12 and ( )-13 that was silylated with triethylsilyl chloride and imidazole.20 This
furnished pure ( )-14 [78% based on ( )-10], after purification by flash chromatography on silica
gel. Alkaline methanolysis21 liberated alcohol ( )-15 that was oxidized with the Dess–Martin
periodinane22 to ( )-3 (Scheme 1).

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4663
Scheme 1. Synthesis of racemic ( )-3
Resolution of aldehyde ( )-3 was achieved applying the method of Alexakis and Mangeney23
using (1R,2R)-(+)-1,2-diphenylethylenediamine that gave a 1:1 mixture of aminals (−)-16 and
(+)-17 in 77% yield based on ( )-14. They were separated by column chromatography on silica
gel. Acidic extraction of (−)-16 (1N HCl/Et2O) liberated (−)-3 in 95% yield and the chiral
1
diamine that was recovered in 91% yield. The H NMR spectrum of (−)-3 is consistent with the
chair conformation shown in Scheme 1 (3J(Haxial-5,Haxial-6)=9.2 Hz, 2D-NOESY). Desilylation
of (−)-16 with HF in pyridine24 led to simultaneous aminal hydrolysis and hemiacetal formation
giving a 2:1 mixture of b-18 and a-18. It was converted into a 1.7:1 mixture of the corresponding
methyl glycosides a-19 and b-19 on treatment with methanol and SOCl2. Reduction of the azides
of 19 by hydrogenation catalyzed with Raney-nickel afforded a 1.7:1 mixture of a-20 and b-20
(Scheme 2).

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F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
Scheme 2. Resolution of ( )-3
Treatment of this mixture with 3 equivalents of p-methoxybenzoyl chloride in pyridine
with a catalytical amount of 4-dimethylaminopyridine gave the corresponding amido-esters
a-21 and b-21 that were separated by high pressure liquid chromatography. The circular
dichroism spectra (Fig. 1) of these compounds showed positive Cotton effects at u=260 nm
and weak Cotton effects at u=240 nm for a maximum of absorption in the UV spectrum
appearing at u=248 nm (m=15800). This is indicative of the existence of an exciton due to
the coupling of the p-methoxybenzoate at C-7 and the p-methoxybenzamido at C-6. The
positive Cotton effect at the highest wavelength is consistent with a positive coupling between
these two chromophores,25 as expected for both a-21 and b-21. The tetrahydropyran moieties
of these compounds adopt preferred chair conformation as shown in Fig. 1. This was
confirmed by the 3J(H,H) coupling constants measured in their 1H NMR spectra, thus
establishing the absolute configuration of these compounds and of their precursors. This
allowed us to assign the -allo-heptose configuration to (−)-3. Because of the distance sepa-
L
rating the benzyloxy group from the p-methoxybenzoate and p-methoxybenzamide chrom-
ophores in a-21 and b-21, the benzyloxy group is not expected to contribute significantly to
the sign of the highest wavelength Cotton effect (u=260 nm) arising from the exciton
coupling of the two p-methoxybenzoyl chromophores. It may nevertheless contribute to the
lower wavelength Cotton effect (u=240 nm) making the latter effect less negative than
expected for an ideal p-methoxybenzoate and p-methoxybenzamido couplet.
The enantiomeric excess (ee) of (−)-3 was determined by Mosher’s esters 22 derived
from the mixture of alcohols a-19 and b-19 and from (S)-(+)- and (R)-(−)-(tri-
fluoromethyl)(methoxy)phenylacetyl chloride. By 19F NMR and comparing with the satellite

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4665
Figure 1. Circular dichroism of a-21 and b-21
signals due to the 13C–19F couplings, the diastereomeric excesses of esters (R)-a-22, (R)-b-22,
(S)-a-22 and (S)-b-22 were better than 98%. Applying the proton chemical shift criteria of Dale
and Mosher26 (see Scheme 3, lH of Heq-2, H-4), the absolute configuration shown for these
compounds is confirmed.
Scheme 3. Mosher’s esters; the Dale–Mosher method for the determination of the absolute configuration (lH (CDCl3,
25°C) ppm)

4666
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
3. Conclusions
Starting from inexpensive starting materials such as furfuryl alcohol and acetone, (−)-3, a
protected form of 2,6-anhydro-5-azido-3,5-dideoxy-2-C-hydroxymethyl- -allo-heptose, has been
L
prepared in 14% overall yield and with high enantiomeric excess (>98%). This compound is a
potential precursor of C-glycosides including neuraminic acid derivatives. The method relies on
the diastereoselective [4+3]-cycloaddition of 1,3-dibromo-2-oxyallyl cation to 2-[(benzyl-
oxy)methyl]furan and on resolution via aminals derived from (1R,2R)-(+)-1,2-diphenylethylene-
diamine. Although it involves 16 steps, the isolation and purification of only seven intermediates
is required. At the same time, the enantiomeric form with the
D
-allo configuration is obtained
with the same ease. Aldehydes (−)-3 and (+)-3 will be used to generate C-linked disaccharides
and analogs of biological interest, applying methodology already available.9–11
4. Experimental section
General, see Ref. 27. Circular dichroism spectra were recorded on a Jobin Yvon Mark VI
instrument using cubic quartz cell (length 0.1 cm) and calibrated with
acid.
D
-(+)-10-camphorsulfonic
4.1. (1RS,2RS,4SR,5RS)-1-[(Benzyloxy)methyl]-2-endo,4-endo-dibromo-8-oxabicyclo[3.2.1]-
oct-6-en-3-one ( )-4
A 1.1 M soln of Et2Zn in toluene (50 mL, 55 mmol) was added dropwise to a soln of
1,1,3,3-tetrabromopropan-2-one14 (15 g, 40.1 mmol) and 2-[(benzyloxy)methyl]furan 113 (5 g,
26.6 mmol) in toluene (250 mL) stirred at 0°C. After stirring at 0°C for 105 min, the mixture was
allowed to warm to 20°C and stirred for a further 75 min. After the addition of EtOAc (50 mL)
and of a sat. aq. soln of NH4Cl (50 mL), the mixture was filtered through a pad of Celite (6 cm).
The aq. phase was extracted with EtOAc (50 mL, three times). The combined org. extracts were
washed with a sat. soln of NH4Cl (20 mL, three times), dried (MgSO4) and concentrated. The
residue resulting from 12 reaction runs were combined and recrystallized from light petroleum
ether/Et2O (3:1): white crystals (28.3 g). FC of the residual red oil (silica gel, light petroleum
ether/Et2O (3:1), Rf (4)=0.25) afforded more white solid 4 (32.6 g) and an orange oil (20.7 g).
Yield of ( )-4: as crystals (60.9 g, 47.5%); as oil (20.7 g, 16%). Mp: 72–73°C. UV (CH3CN):
umax=210 nm (m=8300 [dm3 cm−1 mol−1]). IR (KBr): 3060, 2950, 2870, 2360, 1745, 1495, 1455,
1
1370, 1335, 1310, 1265, 1215, 1075, 1010, 940, 865, 850, 820 cm−1. H NMR (CDCl3, 400 MHz):
3
3
7.38–7.17 (m, 5H(Ph)); 6.55 (dd, J(H-6,H-7)=6.1 Hz, J(H-6,H-5)=1.8 Hz, H-6); 6.28 (d,
3J(H-7,H-6)=6.1 Hz, H-7); 5.2 (dd, J(H-5,H-4)=4.8 Hz, J(H-5,H-6)=1.8 Hz, H-5); 5.16 (s,
3
3
3
2
H-2); 4.87 (d, J(H-4,H-5)=4.8 Hz, H-4); 4.72, 4.64 (2d, J=12.1 Hz, CH2(Bn)); 4.08, 3.80 (2d,
2J=10.9 Hz, 2H-1%). 13C NMR (CDCl3, 100.6 MHz): 190.6 (s, C3); 142.7 (s, Car); 134.7 (d,
1J=178 Hz, C6); 133.9 (d, 1J=173 Hz, C7); 128.5 (d, 1J=158 Hz, 2CHar); 128.0 (d, 1J=161 Hz,
2CHar); 127.9 (d, 1J=161 Hz, CHar); 91.3 (s, C1); 82.6 (d, 1J=166 Hz, C5); 73.9 (t, 1J=142 Hz,
CH2(Bn)); 69.3 (t, J=143 Hz, C1%); 57.4 (d, J=154 Hz, C2); 54.7 (d, J=153 Hz, C4).
CI-MS(NH3): m/z 420 (3, [M+NH4]+), 402 (1, [M°]+), 323 (6, [M−79Br]+), 321 (5, [M−81Br]+), 277
(4), 275 (4), 217 (2), 215 (2), 121 (5), 91 (100). Anal. calcd for C15H14Br2O3 (402.09): C, 44.80;
H, 3.50; Br, 39.70. Found: C, 44.72; H, 3.63; Br, 39.65.
1
1
1

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4667
4.2. (1RS,2SR,3SR,4RS,5RS)-1-[(Benzyloxy)methyl]-2-endo,4-endo-dibromo-8-oxabicyclo-
[3.2.1]oct-6-en-3-endo-ol ( )-5
NaBH4 (1.91 g, 50.4 mmol; 2.07 g, 54.8 mmol) were added portionwise to a soln of pure ( )-4
(13.5 g, 33.6 mmol; 14.7 g, 36.5 mmol) and CeCl3·7H2O (13.8 g, 36.9 mmol; 15.0 g, 40.2 mmol)
in MeOH (420 mL, 450 mL) stirred at 0°C. After 30 min, the soln resulting from two reaction
runs were combined and treated with H2O (100 mL) and 1N HCl (200 mL). The methanol was
evaporated and the aq. phase was extracted with EtOAc (300 mL, four times). The combined
org. extracts were washed with a sat. aq. soln of NaHCO3 (100 mL, two times), dried (MgSO4)
and concentrated: white solid (27.8 g, 98%). An analytical sample of ( )-5 can be obtained by
FC on silica gel (EtOAc/light petroleum ether (1:3), Rf (( )-5)=0.32). Mp: 90–92°C. UV
(CH3CN): umax=213 nm (m=5700 [dm3 cm−1 mol−1]). IR (KBr): 3475, 1595, 1495, 1450, 1420,
1
1365, 1350, 1325, 1300, 1250, 1205, 1195, 1105, 1095, 1070, 1050, 995 cm−1. H NMR (CDCl3,
3
3
400 MHz): 7.43–7.28 (m, 5H(Ph)); 6.55 (dd, J(H-6,H-7)=6.1 Hz, J(H-6,H-5)=1.8 Hz, H-6);
3
3
3
6.23 (d, J(H-7,H-6)=6.1 Hz, H-7); 4.88 (dd, J(H-5,H-4)=3.6 Hz, J(H-5,H-6)=1.8 Hz, H-5);
3
2
3
4.72 (d, J(H-2,H-3)=4.8 Hz, H-2); 4.67, 4.60 (2d, CH2(Bn), J=12.1 Hz); 4.48 (dd, J(H-4,H-
3
3
3
3)=4.8 Hz, J(H-4,H-5)=3.6 Hz, H-4); 4.48 (ddd, J(H-3,OH)=5.5 Hz, J(H-3,H-4)=4.8 Hz,
3J(H-3,H-2)=4.8 Hz, H-3); 3.97, 3.64 (2d, J=10.9 Hz, CH2-C1); 2.59 (d, J(OH,H-3)=5.5 Hz,
2
3
OH). 13C NMR (CDCl3, 100.6 MHz): 137.4 (s, Car); 135.1 (d, J=176 Hz, C6); 135.1 (d,
1
1J=175 Hz, C7); 128.2 (d, 1J=161 Hz, 2CHar); 127.7 (d, 1J=159 Hz, 2CHar); 127.7 (d, 1J=160
1
1
Hz, CHar); 88.8 (s, C1); 82.7 (d, J=162 Hz, C5); 73.9 (t, J=142 Hz, CH2(Bn)); 70.2 (t,
1J=143 Hz, CH2-C1); 69.1 (d, J=155 Hz, C3); 52.3 (d, J=157 Hz, C2); 50.4 (d, J=154 Hz,
C4). CI-MS(NH3): m/z 422 (37, [M+NH4]+), 298 (27, [M+H−OCH2Ph]+), 244 (6), 227 (8), 201
(4), 130 (78), 114 (40), 108 (22), 91 (100). Anal. calcd for C15H16Br2O3 (404.10): C, 44.70; H,
3.75; Br, 39.60. Found: C, 44.63; H, 3.85; Br, 39.55.
1
1
1
4.3. (1RS,2SR,3SR,4SR,5RS)-1-[(Benzyloxy)methyl)-2-endo,4-endo-dibromo-3-(methoxy-
methoxy)-8-oxabicyclo[3.2.1]oct-6-ene ( )-6
P2O5 was added portionwise until completion of reaction to a soln of crude ( )-5 (13.8 g, 34.2
mmol) in a mixture of CH2Cl2 (135 mL) and dimethoxymethane (100 mL) stirred at 20°C. The
mixtures resulting from two runs were combined and treated with CH2Cl2 (200 mL) and a sat.
aq. soln of NH4Cl (until destruction of residual P2O5). The aq. phase was extracted with CH2Cl2
(300 mL, four times). The combined org. extracts were washed with a sat. aq. soln of NaHCO3
(100 mL, two times), dried (MgSO4) and concentrated to afford a yellow solid. Recrystallization
from light petroleum ether gave pure ( )-6 as white solid (26.3 g) and FC of the residual yellow
oil (silica gel, light petroleum ether/Et2O (3:1), Rf (( )-6)=0.19) afforded 1.8 g of white ( )-6.
(Total mass=28.1 g; 89% based on ( )-5.) Mp: 59–60°C. UV (CH3CN): umax=208 nm (m=6800
[dm3 cm−1 mol−1]). IR (KBr): 3435, 3030, 2900, 1600, 1495, 1450, 1370, 1345, 1325, 1270, 1210,
1
1160, 1110, 1035, 1010, 925, 895, 865, 840, 730, 700, 645 cm−1. H NMR (CDCl3, 400 MHz):
3
3
7.40–7.28 (m, 5H(Ph)); 6.50 (dd, J(H-6,H-7)=6.1 Hz, J(H-6,H-5)=1.8 Hz, H-6); 6.23 (d,
3J(H-7,H-6)=6.1 Hz, H-7); 4.84 (dd, J(H-5,H-4)=3.3 Hz, J(H-5,H-6)=1.8 Hz, H-5); 4.75 (d,
3
3
3J(H-2,H-3)=4.8 Hz, H-2); 4.74 (s, CH2(MOM)); 4.67, 4.60 (2d, J=12.4 Hz, CH2(Bn)); 4.52
2
3
3
3
3
(dd, J(H-4,H-3)=4.8 Hz, J(H-4,H-5)=3.3 Hz, H-4); 4.04 (dd, J(H-3,H-4)=4.8 Hz, J(H-
3,H-2)=4.8 Hz, H-3); 3.98, 3.64 (2d, J=10.6 Hz, CH2-C1); 3.50 (s, Me(MOM)). 13C NMR
2
1
1
(CDCl3, 100.6 MHz): 137.6 (s, Car); 134.7 (d, J=176 Hz, C6); 133.6 (d, J=175 Hz, C7); 128.3

4668
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
1
1
1
(d, 2CHar); 127.9 (d, J=158 Hz, 2CHar); 127.7 (d, J=159 Hz, CHar); 99.9 (t, J=164 Hz,
1
1
1
CH2(MOM)); 88.9 (s, C1); 83.0 (d, J=161 Hz, C5); 76.4 (d, J=148 Hz, C3); 73.8 (t, J=143
1
1
1
Hz, CH2(Bn)); 70.5 (t, J=142 Hz, CH2-C1); 57.4 (q, J=142 Hz, Me(MOM)); 51.9 (d, J=152
Hz, C2); 50.2 (d, J=153 Hz, C4). CI-MS(NH3): m/z 466 (35, [M+NH4]+), 342 (12, [M+H−
1
OBn]+), 306 (2, [M−81Br−OMOM]+), 244 (9), 227 (13), 201 (4), 91 (100). Anal. calcd for
C17H20Br2O4 (448.15): C, 45.56; H, 4.50; Br, 35.66. Found: C, 45.63; H, 4.51; Br, 35.64.
4.4. (2RS,3SR,4SR,5SR,6RS)-2-[(Benzyloxy)methyl]-3,5-dibromo-3,4,5,6-tetrahydro-4-
(methoxymethoxy)-2H-pyran-2,6-dimethanol ( )-7
O3 (3% O3 in O2) was bubbled through a soln of pure ( )-6 (28.1 g, 62.6 mmol) in
CH2Cl2/MeOH (500 mL/125 mL) containing some NaHCO3 cooled at −78°C, until the soln
turned blue (60 min). Then, O2 was bubbled to eliminate the excess of ozone and Me2S was
added (10.6 mL, 144 mmol). After stirring for 15 min at −78°C, NaBH4 (5.45 g, 144 mmol) was
added portionwise and the soln was allowed to warm to 20°C. After 2 h at 20°C, the soln was
treated with H2O (50 mL), 1N HCl (100 mL) and the methanol was evaporated. The aq. phase
was extracted with EtOAc (300 mL, four times). The combined org. layers were washed with a
sat. aq. soln of NaHCO3 (100 mL), dried (MgSO4) and concentrated to furnish a white foam
(31.5 g, 100%). An analytical sample of ( )-7 can be obtained by FC on silica gel (EtOAc/light
petroleum ether (2:1), Rf (( )-7)=0.28). UV (CH3CN): umax=268 nm (m=2200 [dm3 cm−1
mol−1]), 205 (7500), 196 (8500). IR (film): 3380, 2935, 1710, 1455, 1365, 1310, 1265, 1215, 1150,
1
1115, 1040, 965, 920, 820, 735, 700 cm−1. H NMR (CDCl3, 400 MHz): 7.40–7.30 (m, 5H(Ph));
4.82 (s, CH2(MOM)); 4.57 (s, CH2(Bn)); 4.48 (d, 3J(H-3,H-4)=4.1 Hz, H-3); 4.40 (dd,
3J(H-4,H-5)=4.1 Hz, 3J(H-4,H-3)=4.1 Hz, H-4); 4.38 (dd, 3J(H-5,H-4)=4.1 Hz, 3J(H-5,H-6)=
3
3
3
2
2.8 Hz, H-5); 4.16 (ddd, J=8.1 Hz, J=4.3 Hz, J(H-6,H-5)=2.8 Hz, H-6); 4.01 (dd, J=11.8
3
2
Hz, J=8.1 Hz, H-C-C6); 3.92, 3.86 (2d, J=12.0 Hz, BnOCH2-C2); 3.84 (s, HOCH2-C2); 3.74
(dd, J=11.8 Hz, J=4.3 Hz, H%-C-C6); 3.47 (s, Me(MOM); 2.05 (br.s, 2H(OH)). 13C NMR
2
3
1
1
(CDCl3, 100.6 MHz): 137.1 (s, Car); 128.6 (d, J=160 Hz, 2CHar); 128.1 (d, J=161 Hz,
1
1
2CHar); 127.8 (d, J=158 Hz, CHar); 95.8 (t, J=167 Hz, CH2(MOM)); 78.6 (s, C2); 73.9 (d,
1
1
1
1J=143 Hz, C6); 73.8 (t, J=140 Hz, CH2(Bn)); 72.5 (t, J=144 Hz, CH2-C2); 71.2 (d, J=143
1
1
1
Hz, C4); 67.5 (t, J=147 Hz, CH2-C2); 64.9 (t, J=157 Hz, CH2-C6); 56.7 (q, J=143 Hz,
1
1
Me(MOM)); 51.1 (d, J=154 Hz, C3); 43.3 (d, J=153 Hz, C5). CI-MS(NH3): m/z 502 (1,
[M+NH4]+), 485 (4, [M+H]+), 484 (4, [M]+), 469 (1, [M−Me]+), 453 (10, [M−OMe]+), 441 (4), 375
(2), 331 (3), 221 (2), 219 (2), 91 (100). Anal. calcd for C17H24Br2O6 (484.19): C, 42.17; H, 4.99;
Br, 33.00. Found: C, 42.30; H, 4.90; Br, 32.95.
4.5. (2RS,5RS,6RS)-5-Azido-2-[(benzyloxy)methyl]-5,6-dihydro-4-(methoxymethoxy)-
2H-pyran-dimethanol ( )-8
Sodium azide (21.1 g, 325 mmol) was added to a soln of crude ( )-7 (31.5 g, 65.1 mmol) in
HMPA (350 mL) at 20°C. After stirring for 100 h at 20°C, HMPA was evaporated under
reduced pressure (P=10−1 torr, Tvap=72°C) to afford a dark oil. An analytical sample of ( )-8
can be obtained by FC on silica gel (EtOAc/light petroleum ether (1:3), Rf (( )-8)=0.46): white
foam (100%). UV (CH3CN): umax=216 nm (m=4700 [dm3 cm−1 mol−1]). IR (film): 3385, 2940,
1
2865, 2110, 1710, 1670, 1455, 1365, 1265, 1220, 1155, 1000, 925, 880, 835, 735, 700 cm−1. H

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4669
2
NMR (CDCl3, 400 MHz): 7.38–7.29 (m, 5H(Ph)); 5.07, 5.01 (2d, J=6.4 Hz, CH2(MOM)); 5.00
4
2
3
(d, J(H-3,H-5)=0.9 Hz, H-3); 4.57, 4.52 (2d, J=12.1 Hz, CH2(Bn)); 4.08 (dd, J(H-5,H-6)=
4
2
3
9.1 Hz, J(H-5,H-3)=0.9 Hz, H-5); 3.84 (dd, J=12.1 Hz, J=2.4 Hz, H-C-C6); 3.72 (dd,
2J=12.1 Hz, J=4.2 Hz, H%-C-C6); 3.71, 3.53 (2d, J=11.2 Hz, BnOCH2-C2); 3.62, 3.46 (2d,
3
2
2J=10.6 Hz, HOCH2-C2); 3.59 (ddd, J(H-6,H-5)=9.1 Hz, J=4.2 Hz, J=4.2 Hz, H-6); 3.47
3
3
3
(s, Me(MOM)). 13C NMR (CDCl3, 100.6 MHz): 151.1 (s, C4); 137.6 (s, Car); 128.4 (d, J=160
1
1
1
1
Hz, 2CHar); 127.8 (d, J=161 Hz, CHar); 127.5 (d, J=158 Hz, 2CHar); 100.2 (d, J=159 Hz,
1
1
C3); 93.8 (t, J=166 Hz, CH2(MOM)); 77.4 (s, C2); 73.4 (t, J=143 Hz, CH2(Bn)); 73.2 (d,
1J=145 Hz, C6); 70.9 (t, J=141 Hz, CH2-C2); 67.2 (t, J=145 Hz, CH2-C2); 61.9 (t, J=144,
1
1
1
1
1
CH2-C6); 56.3 (q, J=143 Hz, Me(MOM)); 54.4 (d, J=146 Hz, C5). CI-MS(NH3): m/z 383 (3,
[M+NH4]+), 334 (1, [M−OMe]+), 304 (2, [M−OMOM]+), 244 (1), 192 (2), 174 (7), 148 (61), 131
(75), 103 (71), 91 (30). Anal. calcd for C17H23N3O6 (365.39): C, 55.88; H, 6.34; N, 11.50. Found:
C, 55.72; H, 6.5; N, 11.46.
4.6. (2RS,5RS,6SR)-5-Azido-2-[(benzyloxy)methyl]-2,3,5,6-tetrahydro-2,6-bis(hydroxymethyl)-
4H-pyran-4-one ( )-9
5N HCl (65 mL, 325 mmol) was added to a soln of crude ( )-8 (65 mmol) in THF (400 mL)
stirred at 20°C. After 1 day, the mixture was diluted with Et2O (400 mL). The aq. phase was
extracted with Et2O (400 mL, three times). The combined org. extracts were washed with a sat.
aq. soln of NaHCO3 (100 mL, two times), dried (MgSO4) and concentrated. The residual dark
oil was filtered through a pad of silica gel (height: 7 cm, diam. 10 cm) using CH2Cl2/MeOH
(100:4) as eluant to afford a brown foam (20.5 g). An analytical sample of ( )-9 can be obtained
by FC on silica gel (CH2Cl2/MeOH (100:3), Rf=0.08) to afford a white foam (73–82%). UV
(CH3CN): umax=211 nm (m=5300 [dm3 cm−1 mol−1]). IR (film): 3420, 2115, 1635, 1495, 1455,
1
1410, 1365, 1270, 1210, 1040, 690 cm−1. H NMR (CDCl3, 400 MHz): 7.39–7.25 (m, 5H(Ph));
4.50, 4.46 (2d, 2J=12.1 Hz, CH2(Bn)); 4.05 (ddd, 3J(H-6,H-5)=10.0 Hz, 3J=3.3 Hz, 3J=2.1 Hz,
3
2
3
H-6); 3.99 (d, J(H-5,H-6)=10.0 Hz, H-5); 3.89 (dd, J=12.1 Hz, J=2.1 Hz, H-C-C6); 3.75
2
3
2
(dd, J=12.1 Hz, J=3.3 Hz, H%-C-C6); 3.64, 3.42 (2d, J=11.8 Hz, BnOCH2-C2); 3.64, 3.43
(2d, J=10.3 Hz, HOCH2-C2); 2.77, 2.52 (2d, J=14.5 Hz, 2H-3); 2.70 (br.s, 2H(OH)). 13C
2
2
NMR(CDCl3, 100.6 MHz): 201.9 (s, C4); 136.8 (s, Car); 128.5 (d, 1J=161 Hz, 2CHar); 128.0 (d,
1J=161 Hz, CHar); 128.0 (d, J=158 Hz, 2CHar); 80.1 (s, C2); 76.0 (d, J=143 Hz, C6); 73.7
1
1
1
1
1
(t, J=143 Hz, CH2(Bn)); 72.8 (t, J=143 Hz, CH2-C2); 66.5 (t, J=145 Hz, CH2-C2); 62.7 (d,
1J=144 Hz, C5); 62.5 (t, 1J=145 Hz, CH2-C6); 42.9 (t, 1J=131 Hz, C3). CI-MS (NH3): m/z 339
(0.3, [M+NH4]+), 294 (0.5, [M+H−N2]+), 279 (0.4), 262 (0.5), 216 (0.4), 91 (100). Anal. calcd for
C17H23N3O6 (321.34): C, 56.07; H, 5.96. Found: C, 56.02; H, 6.05.
4.7. (2RS,5RS,6SR)−5-Azido-2-[(benzyloxy)methyl]-2,3,5,6-tetrahydro-2-(hydroxymethyl)-
6-{[(triisopropylsilyl)oxy]methyl}-4H-pyran-4-one ( )-10
Triisopropylsilyl chloride (13.6 mL, 64 mmol) was added dropwise (using an automatic
syringe) to a soln of crude ( )-9 (20.5 g) and imidazole (8.67 g, 127 mmol) in DMF (350 mL)
stirred at −60°C. At the end of the addition (4 h), the reaction was allowed to warm to 20°C.
After stirring for 21 h at 20°C, the mixture was treated with Et2O (200 mL), and a sat. aq. soln
of NaHCO3 (100 mL). The aq. phase was extracted with Et2O (200 mL, five times). The

4670
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
combined org. layers were washed with a sat. aq. soln of NaHCO3 (100 mL, two times), dried
(MgSO4), and concentrated. The residual DMF was evaporated under reduced pressure. FC
(silica gel, light petroleum ether/EtOAc (3:1)) affords ( )-10 as a colorless oil (16.2 g, 54%
based on ( )-6, Rf (( )-10)=0.20) and ( )-9 (2.85 g, 14% based on ( )-6). Converted yield of
( )-10 (63%). UV (CH3CN): umax=263 nm (m=1000 [dm3 cm−1 mol−1]), 213 nm (8900). IR
1
(film): 3440, 2945, 2885, 2115, 1730, 1650, 1455, 1270, 1095, 880, 740, 680 cm−1. H NMR
3
(CDCl3, 400 MHz): 7.40–7.24 (m, 5H(Ph)); 4.47 (br.s, CH2(Bn)); 4.15 (d, J(H-5,H-6)=9.8 Hz,
3
3
3
2
H-5); 4.07 (ddd, J(H-6,H-5)=9.8 Hz, J=2.9 Hz, J=1.7 Hz, H-6); 3.97 (dd, J=11.2 Hz,
3J=1.7 Hz, H-C-C6); 3.92 (dd, J=11.2 Hz, J=2.9 Hz, H%-C-C6); 3.58, 3.39 (2d, J=11.5
2
3
2
2
2
Hz, BnOCH2-C2); 3.58, 3.41 (2d, J=10.4 Hz, HOCH2-C2); 2.78, 2.53 (2d, J=14.4 Hz,
2H-3); 2.17 (br.s, H(OH)); 1.18–1.05 (m, 21H(TIPS)). 13C NMR (CDCl3, 100.6 MHz): 202.3
1
1
(s, C4); 137.0 (s, Car); 128.5 (d, J=161 Hz, 2CHar); 127.9 (d, J=161 Hz, CHar); 127.8 (d,
1J=158 Hz, 2CHar); 79.6 (s, C2); 76.9 (d, J=149 Hz, C6); 73.6 (t, J=142 Hz, CH2(Bn));
1
1
1
1
1
73.2 (t, J=142 Hz, CH2-C2); 66.6 (t, J=145 Hz, CH2-C2); 63.2 (t, J=144 Hz, CH2-C6);
1
1
1
62.8 (d, J=141 Hz, C5); 43.0 (t, J=145 Hz, C3); 17.9 (q, J=126 Hz, 6Me(TIPS)); 11.9 (d,
1J=117 Hz, 3CH(TIPS)). CI-MS(NH3): m/z 495 (7, [M+NH4]+), 450 (2, [M+H−N2]+), 406 (2,
[M−N2−i-Pr]+), 358 (10, [M−N2−Bn]+), 296 (4), 203 (4), 161 (7), 91 (80), 75 (100).
4.8. (2RS,5SR,6RS)-2-[(Acetyloxy)methyl]-5-azido-2-[(benzyloxy)methyl]-2,3,5,6-tetrahydro-
6-{[(triisopropylsilyl)oxy]methyl]-4H-pyran-4-one ( )-11
Ac2O (60 mL) was added to a soln of pure ( )-10 (7.07 g, 14.8 mmol) in pyridine (60 mL)
stirred at 0°C. After 1 h, the reaction was treated with Et2O (200 mL) and 1N HCl (50 mL).
The aq. phase was extracted with Et2O (200 mL, four times). The combined org. extracts were
washed with a sat. aq. soln of NaHCO3 (until neutrality of aq. phase), dried (MgSO4) and
concentrated. The residual pyridine was evaporated under reduced pressure to afford a light
yellow oil (7.3 g, 95%). An analytical sample of ( )-11 can be obtained by FC on silica gel
(light petroleum ether/EtOAc (4:1) (Rf (light petroleum ether/EtOAc (3:1))=0.40)): colorless
oil. UV (CH3CN): umax=208 nm (m=6700 [dm3 cm−1 mol−1]). IR (film): 3440, 2960, 2865,
1
2115, 1730, 1650, 1455, 1380, 1365, 1240, 1145, 1100, 1050, 995, 885, 735, 700 cm−1. H NMR
3
(CDCl3, 400 MHz): 7.39–7.23 (m, 5H(Ph)); 4.48 (s, CH2(Bn)); 4.19 (br.d, J(H-5,H-6)=9.5 Hz,
2
3
3
H-5); 4.06, 4.00 (2d, J=11.2 Hz, BnOCH2-C2); 4.01 (ddd, J(H-6,H-5)=9.5 Hz, J=2.9 Hz,
3J=1.4 Hz, H-6); 3.97 (dd, J=11.5 Hz, J=1.4 Hz, H-C-C6); 3.89 (dd, J=11.5 Hz, J=2.9
2
3
2
3
2
2
Hz, H%-C-C6); 3.58, 3.47 (2d, J=10.4 Hz, AcOCH2-C2); 2.62 (d, J=14.9 Hz, H-3); 2.50 (dd,
2J=14.9 Hz, J(H%-3,H-5)=0.9 Hz, H%-3); 2.02 (s, Me(Ac)); 1.20–1.00 (m, 21H(TIPS)). 13C
4
1
NMR (CDCl3, 100.6 MHz): 201.6 (s, C4); 170.3 (s, CꢀO(Ac)); 136.9 (s, Car); 128.5 (d, J=161
Hz, 2CHar); 127.9 (d, J=161 Hz, CHar); 127.8 (d, J=158 Hz, 2CHar); 77.8 (s, C2); 76.7 (d,
C6); 73.6 (t, J=141 Hz, CH2(Bn)); 72.3 (t, J=142 Hz, CH2-C2); 67.1 (t, J=149 Hz,
1
1
1
1
1
1
1
1
CH2-C2); 63.1 (t, J=143 Hz, CH2-C6); 62.9 (d, J=139 Hz, C5); 44.0 (t, J=131 Hz, C3);
20.6 (q, 1J=130 Hz, Me(Ac)); 17.9 (q, 1J=126 Hz, 6Me(TIPS)); 11.9 (d, 1J=121 Hz,
3CH(TIPS)). CI-MS(NH3): m/z 537 (42, [M+NH4]+), 492 (12, [M+H−N2]+), 476 (17, [M−i-Pr]+
), 448 (15, [M−i-Pr−N2]+), 91 (100). Anal. calcd for C26H41N3O6Si (519.72): C, 60.09; H, 7.95;
N, 8.09; Si, 5.40. Found: C, 60.18; H, 7.89; N, 8.11; Si, 5.32.

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4671
4.9. (2RS,4RS,5RS,6RS)-5-Azido-2-[(benzyloxy)methyl]-4-hydroxy-3,4,5,6-tetrahydro-6-
{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-methanol acetate (( )-12) and
(2RS,4SR,5RS,6RS)-5-azido-2-[(benzyloxy)methyl]-4-hydroxy-3,4,5,6-tetrahydro-6-
{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-methanol acetate ( )-13
NaBH4 (638 mg, 16.9 mmol) was added portionwise to a soln of crude ( )-11 (7.3 g, 14 mmol)
in MeOH (100 mL) stirred at 0°C. After 30 min, the soln was diluted with EtOAc (100 mL), 1N
HCl (50 mL) and the solvents were evaporated. The aq. phase was extracted with EtOAc (200
mL, four times). The combined org. layers were washed with a sat. aq. soln of NaHCO3 (50 mL,
two times), dried (MgSO4) and concentrated to afford 7.65 g of a 14.4:1 mixture of ( )-12 and
(Rf (light petroleum ether/AcOEt (2:1))=0.42) and ( )-13 (Rf (light petroleum ether/AcOEt
(2:1))=0.30). Data for ( )-12. Mp: 84–86°C. UV (CH3CN): umax=262 nm (m=1400 [dm3 cm−1
mol−1]), 208 (8200). IR (KBr): 3430, 2945, 2865, 2105, 1735, 1465, 1385, 1245, 1135, 1095, 1050,
1
1025, 995, 915, 885, 850, 755, 700 cm−1. H NMR (CDCl3, 400 MHz): 7.38–7.28 (m, 5H(Ph));
2
3
3
4.59, 4.54 (2d, J=12.1 Hz, CH2(Bn)); 4.24 (ddd, J(H-4,H-3)=3.6 Hz, J(H-4,H-3)=3.0 Hz,
3J(H-4,H-5)=3.0 Hz, H-4); 4.01, 3.97 (2d, J=11.2 Hz, CH2-C2); 3.93–3.91 (m, CH2-C6); 3.84
2
(ddd, 3J(H-6,H-5)=10.0 Hz, 3J=2.4 Hz, 3J=2.4 Hz, H-6); 3.74, 3.71 (2d, 2J=10.0 Hz,
3
3
CH2-C2); 3.67 (dd, J(H-5,H-6)=10.0 Hz, J(H-5,H-4)=3.0 Hz, H-5); 2.85 (br.s, H(OH)); 2.06
2
3
2
3
(dd, J=14.8 Hz, J(H-3,H-4)=3.0 Hz, H-3); 2.00 (s, Me(Ac)); 1.74 (dd, J=14.8 Hz, J(H%-
3,H-4)=3.6 Hz, H%-3); 1.11–1.05 (m, 21H(TIPS)). 13C NMR (CDCl3, 100.6 MHz): 170.7 (s,
1
1
CꢀO(Ac)); 137.6 (s, C4); 128.4 (d, J=160 Hz, 2CHar); 127.8 (d, J=159 Hz, CHar); 127.8 (d,
1J=160 Hz, 2CHar); 73.7 (s, C2); 73.5 (t, J=143 Hz, CH2(Bn)); 70.5 (t, J=145 Hz, CH2-C2);
1
1
1
1
1
69.7 (d, J=141 Hz, C6); 68.5 (t, J=150 Hz, CH2-C2); 66.2 (d, J=153 Hz, C4); 63.7 (t,
1J=144 Hz, CH2-C6); 60.1 (d, J=145 Hz, C5); 33.4 (t, J=127 Hz, C3); 20.8 (q, J=129 Hz,
Me(Ac)); 17.9 (q, 1J=127 Hz, 6Me(TIPS)); 11.9 (d, 1J=119 Hz, 3CH(TIPS)). CI-MS(NH3): m/z
539 (10, [M+NH4]+), 478 (9), 91 (100). Anal. calcd for C26H43N3O6Si (521.74): C, 59.86; H, 8.31.
Found: C, 59.72; H, 8.17.
1
1
1
4.10. (2RS,4RS,5SR,6RS)-5-Azido-2-[(benzyloxy)methyl]-3,4,5,6-tetrahydro-4-[(triethylsilyl)-
oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-methanol acetate ( )-14
Et3SiCl (3 mL, 17.6 mmol) was added dropwise to a soln of crude ( )-12 (7.65 g) and
imidazole (2.4 g, 35.1 mmol) in DMF (60 mL) stirred at 0°C. At the end of addition, the
reaction was allowed to warm to 20°C. After stirring for 20 h at 20°C, the mixture was treated
with Et2O (200 mL), and brine (50 mL). The aq. phase was extracted with Et2O (200 mL, five
times). The combined org. layers were washed with a sat. aq. soln of NaHCO3 (100 mL, two
times), dried (MgSO4), and concentrated. The residual DMF was evaporated under reduced
pressure. FC (silica gel, light petroleum ether/EtOAc (4:1)) afforded ( )-14 (8.24 g) as a colorless
oil, contaminated by some Et3SiOH (( )-14/Et3SiOH=2:1). Converted yield: 78% of pure ( )-14
based on ( )-10. UV (CH3CN): umax=273 nm (m=1500 [dm3 cm−1 mol−1]), 224 (3900). IR (film):
1
2945, 2865, 2105, 1745, 1455, 1380, 1240, 1135, 1095, 1070, 1000, 885, 785, 735 cm−1. H NMR
2
(CDCl3, 400 MHz): 7.36–7.25 (m, 5H(Ph)); 4.57, 4.47 (2d, J=12.1 Hz, CH2(Bn)); 4.28 (ddd,
3
3
3J(H-4,H-3)=3.9 Hz, J(H-4,H-3)=3.6 Hz, J(H-4,H-5)=3.0 Hz, H-4); 4.05 (s, CH2-C2);
2
3
3.92–3.89 (m, CH2-C6); 3.83, 3.66 (2d, J=10.0 Hz, CH2-C2); 3.80 (ddd, J(H-6,H-5)=9.7 Hz,
3J=2.4 Hz, J=2.4 Hz, H-6); 3.44 (dd, J(H-5,H-6)=9.7 Hz, J(H-5,H-4)=3.0 Hz, H-5); 1.99
3
3
3
2
3
2
3
(s, Me(Ac)); 1.89 (dd, J=14.2 Hz, J(H-3,H-4)=3.9 Hz, H-3); 1.63 (dd, J=14.2 Hz, J(H%-

4672
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
3
3,H-4)=3.6 Hz, H%-3); 1.11–1.06 (m, 21H(TIPS)); 0.97 (t, J=7.9 Hz, 3Me(TES)); 0.65 (q,
3J=7.9 Hz, 3CH2(TES)). 13C NMR (CDCl3, 100.6 MHz): 170.7 (s, CꢀO(Ac)); 138.3 (s, Car);
1
1
1
128.2 (d, J=160 Hz, 2CHar); 127.6 (d, J=158 Hz, 2CHar); 127.5 (d, J=160 Hz, CHar); 74.2
1
1
1
(s, C2); 73.2 (t, J=142 Hz, CH2(Bn)); 69.1 (d, J=143 Hz, C6); 68.5 (t, J=145 Hz, CH2-C2);
1
1
1
67.9 (t, J=150 Hz, CH2-C2); 67.8 (d, J=147 Hz, C4); 63.9 (t, J=144 Hz, CH2-C6); 59.6 (d,
1J=144 Hz, C5); 34.4 (t, J=126 Hz, C3); 20.8 (q, J=129 Hz, Me(Ac)); 17.9 (q, J=126 Hz,
1
1
1
1
1
1
6Me(TIPS)); 11.9 (d, J=117 Hz, 3CH(TIPS)); 6.8 (q, J=126 Hz, 3Me(TES)); 4.7 (d, J=117
Hz, 3CH2(TES)). CI-MS(NH3): m/z 653 (14, [M+NH4]+), 608 (5, [M+H−N2]+), 592 (5), 578 (2),
564 (3), 91 (100). Anal. calcd for C32H57N3O6Si2 (636.00): C, 60.43; H, 9.03. Found: C, 60.51;
H, 9.02.
4.11. (2RS,4SR,5RS,6SR)-5-Azido-2-[(benzyloxy)methyl]-3,4,5,6-tetrahydro-4-[(triethylsilyl)-
oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-methanol ( )-15
Anh. K2CO3 (5.13 g, 37.1 mmol) was added to a soln of pure ( )-14 (4.72 g, 7.42 mmol) in
MeOH (75 mL) stirred at 20°C. After 40 min, the soln was treated with a sat. aq. soln of
NaHCO3 (30 mL) and the methanol was evaporated. The aq. phase was extracted with EtOAc
(200 mL, three times). The combined org. extracts were washed with a sat. aq. soln of NaHCO3
(30 mL), dried (MgSO4) and concentrated: light yellow oil (4.22 g, 96%). An analytical sample
of ( )-15 (colorless oil) can be obtained by FC (silica gel, EtOAc/light petroleum ether (1:4),
Rf=0.42). UV (CH3CN): umax=260 nm (m=2300 [dm3 cm−1 mol−1]), 257 nm (2400), 212 nm
(7100). IR (film): 3455, 2955, 2870, 2105, 1465, 1415, 1385, 1365, 1255, 1125, 1095, 1065, 1015,
1
995, 885, 785, 740 cm−1. H NMR (CDCl3, 400 MHz): 7.40–7.26 (m, 5H(Ph)); 4.58, 4.48 (2d,
3
3
3
2J=12.1 Hz, CH2(Bn)); 4.32 (ddd, J(H-4,H-3)=3.7 Hz, J(H-4,H-3)=3.2 Hz, J(H-4,H-5)=
2
3
2
3
2.9 Hz, H-4); 3.96 (dd, J=11.1 Hz, J=2.9 Hz, H-C-C6); 3.91 (dd, J=11.1 Hz, J=2.0 Hz,
H%-C-C6); 3.85 (ddd, J(H-6,H-5)=9.8 Hz, J=2.9 Hz, J=2.0 Hz, H-6); 3.80, 3.76 (2d, J=9.5
Hz, CH2-C2); 3.63, 3.44 (2d, J=11.2 Hz, CH2-C2); 3.40 (dd, J(H-5,H-4)=9.8 Hz, J(H-5,H-
4)=2.9 Hz, H-5); 2.15 (br.s, H(OH)); 1.92 (dd, J=14.4 Hz, J(H-3,H-4)=3.7 Hz, H-3); 1.85
3
3
3
2
2
3
3
2
3
2
3
3
(dd, J=14.4 Hz, J(H%-3,H-4)=3.2 Hz, H%-3); 1.19–1.06 (m, 21H(TIPS)); 0.99 (t, J=7.9 Hz,
3Me(TES)); 0.65 (q, J=7.9 Hz, 3CH2(TES)). 13C NMR (CDCl3, 100.6 MHz): 138.3 (s, Car);
3
1
1
1
128.3 (d, J=160 Hz, 2CHar); 127.6 (d, J=161 Hz, 2CHar); 127.5 (d, J=161 Hz, CHar); 75.1
(s, C2); 73.4 (t, J=142 Hz, CH2(Bn)); 70.5 (t, J=143 Hz, CH2-C2); 69.0 (d, J=143 Hz, C6);
1
1
1
1
1
1
68.0 (d, J=146 Hz, C4); 67.9 (t, J=145 Hz, CH2-C2); 63.8 (t, J=141 Hz, CH2-C6); 59.5 (d,
1J=144 Hz, C5); 33.5 (t, 1J=129 Hz, C3); 17.9 (q, 1J=126 Hz, 6Me(TIPS); 11.9 (d, 1J=117 Hz,
1
1
3CH(TIPS)); 6.8 (q, J=126 Hz, 3Me(TES)); 4.7 (d, J=117 Hz, 3CH2(TES)). CI-MS(NH3):
m/z 611 (12, [M+NH4]+), 594 (2, [M+H]+), 566 (4, [M+H−N2]+), 550 (2, [M−i-Pr]+), 536 (2,
[M−N2−Et]+), 522 (8, [M−i-Pr−N2]+), 91 (100). Anal. calcd for C30H55N3O5Si2 (593.96): C, 60.67;
H, 9.34; N, 7.08; Si, 9.45. Found: C, 60.64; H, 9.23; N, 6.93; Si, 9.32.
4.12. (2RS,4RS,5SR,6RS)-5-Azido-2-[(benzyloxy)methyl]-3,4,5,6-tetrahydro-4-[(triethylsilyl)-
oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-carboxaldehyde and ((2RS,4RS,5SR,6RS)-
2,6-anhydro-5-azido-2-C-[(benzyloxy)methyl]-3,5-dideoxy-4-O-triethylsilyl-7-O-triisopropylsilyl-
DL-allo-heptose ( )-3
1,1,1-Triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one (Dess–Martin periodinane) (4.72 g,
11.1 mmol) was added to a soln of crude ( )-15 (4.22 g, 7.10 mmol) in CH2Cl2 (75 mL) stirred

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4673
at 20°C. After stirring for 60 min, the reaction was diluted with CH2Cl2 (50 mL) and a 1 M aq.
soln of Na2S2O3 (30 mL). The aq. soln was extracted with CH2Cl2 (200 mL, three times). The
combined org. extracts were washed with a 1 M aq. soln of Na2S2O3 (30 mL), dried (MgSO4)
and concentrated. The resulting white solid was filtered (3 cm pad of silica gel, EtOAc/light
petroleum ether (1:4) as eluant) to eliminate most of residual Dess–Martin periodinane.
Although aldehyde ( )-3 is not very stable on silica gel, an analytical sample can be obtained by
FC (silica gel, EtOAc/light petroleum ether (1:9), Rf (EtOAc/light petroleum ether (1:4))=0.65)
to afford a colorless oil. UV (CH3CN): umax=206 nm (m=9100 [dm3 cm−1 mol−1]). IR (film):
2955, 2685, 2105, 1740, 1465, 1415, 1365, 1300, 1260, 1135, 1100, 1070, 1030, 995, 885, 735 cm−1.
1H NMR (CDCl3, 400 MHz): 9.61 (d, J=1.1 Hz, H-1); 7.36–7.26 (m, 5H(Ph)); 4.55, 4.46 (2d,
2J=12.4 Hz, CH2(Bn)); 4.24–4.19 (m, H-4+1H of BnOCH2-C2); 3.99–3.97 (m, 2H-7); 3.84 (ddd,
3
3
2
3J(H-6,H-5)=9.2 Hz, J(H-6, H-7)=2.8 Hz, J(H-6,H-7)=2.8 Hz, H-6); 3.56 (d, J=10.9 Hz,
3
3
1H of BnOCH2-C2); 3.48 (dd, J(H-5,H-6)=9.2 Hz, J(H-5,H-4)=2.9 Hz, H-5); 1.78 (dd,
2J=14.4 Hz, J(H-3,H-4)=4.3 Hz, H-3); 1.65 (dd, J=14.4 Hz, J(H%-3,H-4)=2.9 Hz, H%-3);
3
2
3
1.17–1.07 (m, 21H(TIPS)); 0.94 (t, 3J=7.8 Hz, 3Me(TES)); 0.61 (q, 3J=7.8 Hz, 3CH2(TES)). 13
C
1
1
NMR (CDCl3, 100.6 MHz): 203.8 (d, J=183 Hz, C1); 137.8 (s, Car); 128.2 (d, J=160 Hz,
1
1
2CHar); 127.7 (d, J=160 Hz, CHar); 127.7 (d, J=159 Hz, 2CHar); 80.7 (s, C1); 73.5 (t,
1J=142 Hz, CH2(Bn)); 70.0 (t, J=142 Hz, BnOCH2-C2); 69.8 (d, J=145 Hz, C6); 67.1 (d,
1
1
1J=146 Hz, C4); 63.6 (t, J=143 Hz, C7); 59.3 (d, J=142 Hz, C5); 34.0 (t, J=129 Hz, C3);
1
1
1
1
1
1
17.9 (q, J=126 Hz, 6Me(TIPS)); 11.9 (d, J=117 Hz, 3CH(TIPS)); 6.8 (q, J=126 Hz,
3Me(TES)); 4.7 (d, J=116 Hz, 3CH2(TES)). CI-MS(NH3): m/z 609 (99, [M+NH4]+), 592 (10,
1
[M+H]+, 10.2), 564 (27, [M+H−N2]+), 548 (20, [M−i-Pr]+), 534 (16, [M−N2−Et]+), 520 (28,
[M−N2−i-Pr]+), 91 (100). Anal. calcd for C30H53N3O5Si2 (591.94): C, 60.87; H, 9.02; N, 7.10; O,
13.51. Found: C, 60.93; H, 9.15; N, 7.01; O, 13.47.
4.13. (2R,4R,5S,6R)-2,6-Anhydro-5-azido-2-C-[(benzyloxy)methyl]-3,5-dideoxy-4-O-triethyl-
silyl-7-O-triisopropylsilyl- -allo-heptose (−)-3
L
Compound (−)-16 (2.07 g, 2.63 mmol) was dissolved in Et2O (100 mL) and extracted with 1N
HCl (20 mL, three times). The org. phase was washed with a sat. aq. soln of NaHCO3 (until
neutrality), dried (MgSO4) and concentrated to afford (−)-3 (1.48g, 95%): colorless oil. Addition
of NaHCO3 to the aq. phase and extraction with CH2Cl2 (100 mL, three times), drying (MgSO4)
25
577
and concentration allowed recovery of the chiral diamine (507 mg, 91%). [h]25859=−51, [h]
−53, [h]25546=−60, [h]24355=−109, [h]24503=−135 (c=1.0, CHCl3).
=
4.14. (4R,5R)-2-{(2S,4R,5S,6R)-5-Azido-2-[(benzyloxy)methyl]-3,4,5,6-tetrahydro-4-[(triethyl-
silyl)oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-yl}-4,5-diphenylimidazolidine ((−)-16)
and (4R,5R)-2-{(2R,4S,5R,6S)-5-azido-2-[(benzyloxy)methyl]-3,4,5,6-tetrahydro-4-[(triethyl-
silyl)oxy]-6-{[(triisopropylsilyl)oxy]methyl}-2H-pyran-2-yl}-4,5-diphenylimidazolidine (+)-17
(1R,2R)-(+)-1,2-Diphenylethylenediamine (1.89 g, 8.90 mmol) was added to a soln of crude
,
( )-3 (4.39 g) and 4 A molecular sieves (4 g) in CH2Cl2 (75 mL) stirred at 20°C. After 22 h, the
mixture was diluted with CH2Cl2 (100 mL), Et3N (10 mL) and a sat. aq. soln of NaHCO3 (50
mL). The aq. phase was extracted with CH2Cl2 (100 mL, four times). The combined org.
extracts were washed with a sat. aq. soln of NaHCO3 (50 mL), dried (MgSO4) and concen-

4674
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
trated. FC (silica gel, EtOAc/light petroleum ether (1:9)+1% NEt3) afforded (−)-16 (604 mg) and
a mixture of (−)-16 and (+)-17 (3.88 g). (Overall yield based on ( )-14: 77%.) Analytical samples
of (−)-16 and (+)-17 can be obtained by FC (silica gel, EtOAc/light petroleum ether (1:9)+1%
NEt3), Rf (EtOAc/light petroleum ether (1:3)) (−)-16=0.38, Rf (EtOAc/light petroleum ether
(1:3)) (+)-17=0.47: colorless oils.
Data for (−)-16. [h]52859=−30, [h]52757=−31, [h]52546=−35, [h]42535=−55, [h]42053=−63 (c=1.0,
CHCl3). UV (CH3CN): umax=213 nm (m=12700 [dm3 cm−1 mol−1]). IR (film): 2955, 2870, 2105,
1
1495, 1455, 1415, 1380, 1295, 1255, 1115, 1015, 885, 785, 735, 700 cm−1. H NMR (CDCl3, 400
2
MHz): 7.42–7.09 (m, 15H(Ph)); 4.82 (s, H-2); 4.59, 4.55 (2d, J=11.9 Hz, CH2(Bn)); 4.28, 4.14
2
3
(2d, J=9.3 Hz, CH2-C2%); 4.25 (d, J(H-4,H-5)=7.7 Hz, H-4); 4.20–4.16 (m, H-4%+H-5); 4.06
3
3
3
2
3
(ddd, J(H-6%,H-5%)=9.9 Hz, J=2.8 Hz, J=1.9 Hz, H-6%); 4.02 (dd, J=11.1 Hz, J=2.8 Hz,
2
3
3
H-C-C6%); 3.95 (dd, J=11.1 Hz, J=1.9 Hz, H%-C-C6%); 3.56 (dd, J(H-5%,H-6%)=9.9 Hz,
3J(H-5%,H-4%)=2.8 Hz, H-5%); 2.37 (dd, J=14.5 Hz, J(H-3%,H-4%)=3.1 Hz, H-3%); 2.18 (dd,
2
3
2J=14.5 Hz, J(H%-3%,H-4%)=3.7 Hz, H%-3%); 1.21–1.15 (m, 21H(TIPS)); 1.11 (t, J=7.7 Hz,
3
3
3Me(TES)); 0.76 (2q, J=7.7 Hz, 3CH2(TES)). 13C NMR (CDCl3, 100.6 MHz): 142.9, 141.6,
3
1
1
138.7 (3s, 3Car); 128.4–127.1 (9d, Jꢀ160 Hz, 15CHar); 78.6 (d, J=149 Hz, C2); 76.6 (s, C2%);
1
1
1
73.5 (t, J=141 Hz, CH2(Bn)); 71.1 (d, J=139 Hz, C5); 70.3 (t, J=145 Hz, CH2-C2%); 69.9 (d,
1J=143 Hz, C4); 69.2 (d, J=142 Hz, C6%); 68.4 (d, J=149 Hz, C4%); 64.2 (t, J=141 Hz,
1
1
1
1
1
1
CH2-C6%); 60.1 (d, J=142 Hz, C5%); 33.0 (t, J=128 Hz, C3%); 18.0 (q, J=126 Hz, 6Me(TIPS));
1
1
1
12.1 (d, J=118 Hz, 3CH(TIPS)); 6.95 (q, J=126 Hz, 3Me(TES)); 4.9 (d, J=117 Hz,
3CH2(TES)). CI-MS(NH3): m/z 786 (100, [M+H]+), 757 (4, [M−N2]+), 742 (2, [M−i-Pr]+), 681
(4), 636 (6), 609 (9),531(10), 223 (21).
Data for (+)-17. [h]25589=42, [h]52757=43, [h]25546=49, [h]24355=85, [h]24503=105 (c=1.0, CHCl3). UV
(CH3CN): umax=215 nm (m=13100 [dm3 cm−1 mol−1]). IR (film): 2865, 2105, 1495, 1455, 1415,
1365, 1255, 1120, 1015, 885, 745, 700 cm−1. H NMR (CDCl3, 400 MHz): 7.44–7.11 (m,
1
2
2
15H(Ph)); 4.84 (s, H-2); 4.62, 4.54 (2d, J=12.1 Hz, CH2(Bn)); 4.32, 4.04 (2d, J=9.8 Hz,
3
3
3
CH2-C2%); 4.26 (d, J(H-4,H-5)=7.8 Hz, H-4); 4.18 (ddde, J(H-4%,H-5%)=4.0 Hz, J(H-4%,H-
3%)=3.2 Hz, 3J(H-4%,H-3%)=2.9 Hz, H-4%); 4.26 (d, 3J(H-5,H-4)=7.8 Hz, H-5); 4.08 (dm,
3J(H-6%,H-5%)=9.8 Hz, H-6%); 4.01 (dd, J=10.9 Hz, J=3.5 Hz, H-C-C6%); 3.97 (dd, J=10.9
2
3
2
3
3
3
Hz, J=2.5 Hz, H-C-C6%); 3.43 (dd, J(H-5%,H-6%)=9.8 Hz, J(H-5%,H-4%)=2.9 Hz, H-5%); 2.50
2
3
2
(br.s, 2 NH); 2.23 (dd, J=14.4 Hz, J(H-3%,H-4%)=3.2 Hz, H-3%); 2.17 (dd, J=14.4 Hz,
3J(H%-3%,H-4%)=4.0 Hz, H%-3%); 1.21–1.15 (m, 21H(TIPS)); 1.13 (t, J=7.8 Hz, 3Me(TES));
3
0.78+0.77 (2q, J=7.8 Hz, 3CH2(TES)). 13C NMR (CDCl3, 100.6 MHz): 142.9, 141.4, 138.7 (3s,
3
1
3Car); 128.3, 128.2, 128.0, 127.7, 127.5, 127.5, 127.3, 127.3, 127.1 (9d, Jꢀ160 Hz, 15CHar);
78.0 (d, J=153 Hz, C2); 77.2 (s, C2%); 73.5 (t, J=141 Hz, CH2(Bn)); 70.9 (d, J=135 Hz, C5);
1
1
1
1
1
1
70.2 (t, J=145 Hz, CH2-C2%); 69.6 (d, J=138 Hz, C4); 69.4 (d, J=138 Hz, C6%); 68.5 (d,
1J=146 Hz, C4%); 64.3 (t, J=141 Hz, CH2-C6%); 60.3 (d, J=144 Hz, C5%); 32.9 (t, J=129 Hz,
1
1
1
1
1
1
C3%); 17.9 (q, J=126 Hz, 6Me(TIPS)); 12.0 (d, J=118 Hz, 3CH(TIPS)); 6.9 (q, J=126 Hz,
3Me(TES)); 4.9 (d, J=117 Hz, 3CH2(TES)). CI-MS(NH3): m/z 786 (100, [M+H]+), 758 (4,
1
[M+H−N2]+), 742 (3, [M−i-Pr]+), 635 (4, [M−CH2OBn−Et]+), 531 (6), 223 (42)).
4.15. (1R,2R,5R,6R,7R)-6-exo-Azido-1-[(benzyloxy)methyl]-3,9-dioxabicyclo[3.3.1]nonan-
2-exo,7-exo-diol (h-18) and (1R,2S,5R,6R,7R)-6-exo-azido-1-[(benzyloxy)methyl]-3,9-dioxa-
bicyclo[3.3.1]nonan-2-endo,7-exo-diol i-18
HF/pyr (7:3) (1.4 mL, 52.2 mmol) was added to a soln of pure (−)-16 (687 mg, 0.87 mmol)
in THF (15 mL) stirred at 0°C. After 30 min, the mixture was treated with EtOAc (10 mL) and

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4675
a sat. aq. soln of NaHCO3 (5 mL). The aq. phase was extracted with EtOAc (15 mL, three
times). The combined org. extracts were washed with brine (10 mL), dried (MgSO4) and
concentrated. FC (silica gel, EtOAc/light petroleum ether (2:1), Rf (EtOAc)=0.71) afforded a
25
(1:2) mixture of a-18/b-18 (208 mg, 75%). [h]25589=45, [h]25757=49, [h]25546=54, [h]24355=97, [h]
=
403
120 (c=0.5, CHCl3). UV (CH3CN): umax=210 nm (m=6100 [dm3 cm−1 mol−1]). IR (film): 3420,
2920, 2100, 1705, 1495, 1455, 1360, 1265, 1160, 1095, 1020, 910, 880, 825, 735, 700 cm−1.
CI-MS(NH3): m/z 339 (100, [M+NH4]+), 322 (19, [M+H]+), 304 (36, [M−OH]+), 294 (36,
[M+H−N2]+), 276 (15, [M−N2−OH]+), 273 (17), 213 (17), 91 (32). Anal. calcd for C15H19N3O5
1
(321.33): C, 56.07; H, 5.96; N, 13.08. Found: C, 55.95; H, 6.09; N, 13.05. H NMR (CDCl3, 400
MHz) of a-18: 7.38–7.28 (m, 5H(Ph)); 4.90–4.76 (m, H-7+H-2); 4.56 (s, CH2(Bn)); 4.38 (dd,
3
2J=12.4 Hz, J(H-4,H-5)=4.0 Hz, H-4); 4.30–4.23 (m, HO-C2); 4.03 (m, H-5); 3.79–3.71 (m,
2
2
H-6); 3.52, 3.40 (2d, J=9.9 Hz, CH2-C1); 3.40 (d, J=12.4 Hz, H%-4); 2.42 (br.s, HO-C7); 2.00
2
3
2
3
(dd, J=13.6 Hz, J(H-8,H-7)=6.1 Hz, H-8); 1.75 (dd, J=13.6 Hz, J(H%-8,H-7)=11.2 Hz,
H%-8). 13C NMR (CDCl3, 100.6 MHz) of a-18: 137.3 (s, Car); 128.4 (d, J=161 Hz, 2CHar);
1
1
1
1
127.9 (d, J=161 Hz, CHar); 127.7 (d, J=161 Hz, 2CHar); 92.6 (d, J=169 Hz, C2); 74.2 (s,
C1); 73.9 (t, 1J=144 Hz, CH2(Bn)); 73.5 (t, 1J=144 Hz, CH2-C1); 71.0 (d, 1J=148 Hz, C5); 64.3
(d, 1J=142 Hz, C7); 64.1 (d, 1J=138 Hz, C6); 58.5 (t, 1J=147 Hz, C4); 35.2 (t, 1J=129 Hz, C8).
1H NMR (CDCl3, 400 MHz) of b-18: 7.38–7.28 (m, 5H(Ph)); 5.01 (br.s, H-2); 4.20–4.16 (m,
2
2
H-7); 4.63, 4.53 (2d, J=12.1 Hz, CH2(Bn)); 4.30–4.23 (m, HO-C2); 4.02 (dd, J=12.4 Hz,
3J(H-4,H-5)=3.4 Hz, H-4); 3.96 (m, H-5); 3.79–3.71 (m, H-6+H%-4 where J=12.4 Hz); 3.48,
2
2
2
3
3.38 (2d, J=10.5 Hz, CH2-C1); 2.58 (br.s, HO-C7); 2.15 (dd, J=13.3 Hz, J(H-8,H-7)=5.9
2
3
Hz, H-8); 1.48 (dd, J=13.3 Hz, J(H%-8,H-7)=5.9 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz)
1
1
of b-18: 137.6 (s, Car); 128.4 (d, J=161 Hz, 2CHar); 127.9 (d, J=161 Hz, CHar); 127.7 (d,
1J=161 Hz, 2CHar); 94.7 (d, J=166 Hz, C2); 76.1 (s, C1); 73.9 (t, J=144 Hz, CH2(Bn)); 73.5
1
1
1
1
1
1
(t, J=142 Hz, CH2-C1); 70.8 (d, J=149 Hz, C5); 65.9 (t, J=145 Hz, C4); 64.5 (d, J=149
Hz, C7); 63.6 (d, J=142 Hz, C6); 30.8 (t, J=129 Hz, C8).
1
1
4.16. (1R,2S,5R,6R,7R)-6-exo-Azido-1-[(benzyloxy)methyl]-2-endo-methoxy-3,9-dioxabicyclo-
[3.3.1]nonan-7-exo-ol (i-19) and (1R,2R,5R,6R,7R)-6-exo-azido-1-[(benzyloxy)methyl]-
2-exo-methoxy-3,9-dioxabicyclo[3.3.1]nonan-7-exo-ol h-19
SOCl2 (530 mL, 7.34 mmol) was added to a 1:2 soln of a-18/b-18 (118 mg, 0.37 mmol) in
MeOH (10 mL) stirred at 20°C. The mixture was stirred at 60°C for 24 h, then treated with Et2O
(50 mL) and a sat. aq. soln of NaHCO3 (15 mL). The aq. phase was extracted with Et2O (50
mL, three times). The combined org. extracts were washed with brine (20 mL), dried (MgSO4)
and concentrated. FC (silica gel, EtOAc/light petroleum ether (1:1), Rf (EtOAc)=0.88): (1.7:1)
mixture of a-19/b-19 (87 mg, 71%). [h]25589=43, [h]52757=43, [h]25456=45, [h]24535=72, [h]42053=95
(c=0.3, CHCl3); UV (CH3CN): umax=209 nm (m=5700 [dm3 cm−1 mol−1]). IR (film): 3480, 2935,
2120, 1455, 1355, 1270, 1070, 1020, 880, 830, 740, 700 cm−1. CI-MS(NH3): m/z 336 ([M+H]+),
320 (36, [M−Me]+), 307 (0.2, [M−N2]+), 304 (0.3, [M−MeO]+), 276 (0.2, [M−MeO−N2]+), 258
(0.3, [M−Ph]+), 200 (0.6, [M−OBn−N2]+), 134 (0.5), 91 (100); Anal. calcd for C16H21N3O5
1
(335.36): C, 57.29; H, 6.31; N, 12.53. Found: C, 57.34; H, 6.32; N, 12.54. H NMR (CDCl3, 400
MHz) of a-19: 7.38–7.26 (m, 5H(Ph)); 4.84–4.73 (m, H-7); 4.59, 4.46 (2d, 2J=12.1 Hz,
2
3
CH2(Bn)); 4.375 (s, H-2); 4.20 (dd, J=12.1 Hz, J(H-4,H-5)=3.8 Hz, H-4); 4.06–4.00 (m, H-5);
3.84–3.76 (m, H-6); 3.53, 3.34 (2d, 2J=9.2 Hz, CH2-C1); 3.47–3.405 (m, H%-4); 3.39 (s,
2
2
3
3H(MeO)); 2.22 (d, J=9.6 Hz, OH); 2.13 (dd, J=13.7 Hz, J(H-8,H-7)=5.9 Hz, H-8); 1.895

4676
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
2
3
(dd, J=13.7 Hz, J(H%-8,H-7)=11.4 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz) of a-19: 138.1
1
1
1
(s, Car); 128.2 (d, J=159 Hz, 2CHar); 127.7 (d, J=159 Hz, CHar); 127.7 (d, J=159 Hz,
2CHar); 98.5 (d, J=168 Hz, C2); 74.4 (s, C1); 73.6 (t, J=146 Hz, CH2(Bn)); 73.5 (t, J=145
1
1
1
1
1
1
Hz, CH2-C1); 70.8 (d, J=148 Hz, C5); 64.7 (d, J=154 Hz, C7); 64.4 (d, J=143 Hz, C6); 59.0
(t, 1J=149 Hz, C4); 55.3 (q, J=144 Hz, MeO); 35.8 (t, J=131 Hz, C8). H NMR (CDCl3, 400
1
1
1
2
MHz) of b-19: 7.38–7.26 (m, 5H(Ph)); 4.84–4.73 (m, H-7); 4.69 (s, H-2); 4.66, 4.50 (2d, J=12.4
Hz, CH2(Bn)); 4.06–4.00 (m, H-5+H-4); 3.84–3.76 (m, H-6+ H%-4); 3.47–3.405 (m, 1H of
2
2
CH2-C1+3H(MeO)); 3.34 (d, J=10.6 Hz, 1H of CH2-C1); 2.18 (d, J=9.0 Hz, OH); 2.04 (dd,
2J=12.1 Hz, J(H-8,H-7)=6.0 Hz, H-8); 1.44 (dd, J=12.1 Hz, J(H%-8,H-7)=12.1 Hz, H%-8).
3
2
3
13C NMR (CDCl3, 100.6 MHz) of b-19: 138.1 (s, Car); 128.2 (d, J=159 Hz, 2CHar); 127.7 (d,
1
1J=159 Hz, CHar); 127.7 (d, J=159 Hz, 2CHar); 101.1 (d, J=164 Hz, C2); 76.0 (s, C1); 73.6
1
1
1
1
1
(t, J=141 Hz, CH2(Bn)); 73.1 (t, J=143 Hz, CH2-C1); 71.1 (d, J=148 Hz, C5); 65.8 (t,
1J=145 Hz, C4); 64.6 (d, 1J=153 Hz, C7); 63.9 (d, 1J=149 Hz, C6); 56.8 (q, 1J=145 Hz, MeO);
1
31.6 (t, J=133 Hz, C8).
4.17. (1R,2S,5R,6R,7R) 6-exo-Amino-1-[(benzyloxy)methyl]-2-endo-methoxy-3,9-dioxabicyclo-
[3.3.1]nonan-7-exo-ol (i-20) and (1R,2R,5R,6R,7R) 6-exo-amino-1-[(benzyloxy)methyl]-
2-exo-methoxy-3,9-dioxabicyclo[3.3.1]nonan-7-exo-ol h-20
Raney Ni (catalytic amount) was added to a (1.7:1) mixture of a-19/b-19 (22 mg, 0.066 mmol)
in EtOH. It was degassed and then pressurized with H2 (1 atm) stirred at 20°C. After 90 min,
the mixture was diluted with EtOH (10 mL) and filtered through a pad of Celite (2 cm). The
Celite was washed with EtOH (10 mL, two times) and the solvents were evaporated: (1.7:1)
mixture of a-20/b-20 (17 mg, 83%). IR (film): 3425, 2935, 1455, 1360, 1245, 1210, 1070, 1025,
735, 700 cm−1. CI-MS(NH3): m/z 310 (7, [M+H]+), 278 (12, [M−OMe]+), 277 (19, [M+H−OH−
1
NH2]+), 201 (9, [M−Bn−OH]+), 169 (14, [M−OBn−NH2−OH]+), 91 (100, [Bn]+). H NMR
(CDCl3, 400 MHz) of a-20: 7.38–7.25 (m, 5H(Ph)); 4.66–4.44 (m, CH2(Bn)+H-7); 4.34 (s, H-2);
2
3
4.17 (dd, J=12.0 Hz, J(H-4,H-5)=2.8 Hz, H-4); 3.85–3.77 (m, H-5); 3.47–3.30 (m, CH2-C1+
2
H%-4); 3.39 (s, 3H(MeO)); 3.02 (br.s, H-6); 2.57 (br.s, OH+NH2); 2.05 (dd, J=13.9 Hz,
2
3
3J(H-8,H-7)=6.2 Hz, H-8); 1.78 (dd, J=13.9 Hz, J(H%-8,H-7)=12.0 Hz, H%-8). 13C NMR
(CDCl3, 100.6 MHz) of a-20: 138.1 (s, Car); 128.3–127.5 (3d, 5CHar); 98.6 (d, C2); 74.2–73.4
(m, C1+CH2(Bn)+CH2-C1+C5); 62.9 (d, C7); 59.5 (t, C4); 55.1 (q, MeO); 53.0 (d, C6); 34.9 (t,
1
C8). H NMR (CDCl3, 400 MHz) of b-20: 7.38–7.25 (m, 5H(Ph)); 4.66–4.44 (m, CH2(Bn)+H-7+
2
H-2); 4.00 (br.d, J=10.5 Hz, H-4); 3.85–3.77 (m, H-5+H%-4); 3.47–3.30 (m, CH2-C1); 3.44 (s,
2
3
3H(MeO)); 3.02 (br.s, H-6); 2.57 (br.s, OH+NH2); 2.01 (dd, J=13.9 Hz, J(H-8,H-7)=6.5 Hz,
2
3
H-8); 1.28 (dd, J=13.9 Hz, J(H%-8,H-7)=12.0 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz) of
b-20: 137.9 (s, Car); 128.3–127.5 (3d, 5CHar); 101.3 (d, C2); 75.8 (s, C1); 74.2–73.4 (m,
CH2(Bn)+CH2-C1+C5); 66.3 (t, C4); 62.9 (d, C7); 56.7 (q, MeO); 52.6 (d, C6); 30.8 (t, C8).
4.18. (1R,2R,5R,6R,7R)-4-Methoxybenzoic acid 1-[(benzyloxy)methyl]-2-exo-methoxy-
6-[(4-methoxybenzoyl)amino]-3,9-dioxabicyclo[3.3.1]nonan-7-exo-yl ester (i-21) and
(1R,2R,5R,6R,7R)-4-methoxybenzoic acid 1-[(benzyloxy)methyl]-2-exo-methoxy-6-[(4-meth-
oxybenzoyl)amino]-3,9-dioxabicyclo[3.3.1]nonan-7-exo-yl ester h-21
Paramethoxybenzoyl chloride (18.3 mL, 0.135 mmol) and DMAP (catalytic amount) were
added to a (1.7:1) mixture of a-20/b-20 (14 mg, 0.045 mmol) in pyridine (0.5 mL) stirred at

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4677
20°C. After stirring for 20 h, the mixture was treated with MeOH (1 mL) and H2O (1 mL). The
aq. phase was extracted with CH2Cl2 (5 mL, five times). The combined org. extracts were dried
(MgSO4) and concentrated. The residue was first chromatographed to eliminate p-methoxyben-
zoic acid and methyl p-methoxybenzoate. HPLC (EtOAc/light petroleum ether (3:2), Macherey–
Nagel, Nuc 100-5, 6 mL/min, P=48 bar): a-21 (1.5 mg, 6%) and b-21 (0.5 mg, 2%), colorless
oils.
Data for a-21. (CH3CN): umax=248 nm (m=15800 [dm3 cm−1 mol−1]), 212 nm (12900). IR
1
(film): 2925, 1705, 1650, 1605, 1495, 1455, 1260, 1170, 1100, 1075, 1030, 735 cm−1. H NMR
3
3
(CDCl3, 400 MHz): 7.88 (dm, J=9.0 Hz, 2Har); 7.71 (dm, J=8.9 Hz, 2Har); 7.38–7.31 (m,
3
3
3
5H(Ph)); 6.87 (dm, J=8.9 Hz, 2Har); 6.82 (dm, J=9.0 Hz, 2Har); 6.77 (d, J(NH,H-6)=9.1
Hz, NH); 6.15 (ddd, J(H-7,H-8)=11.3 Hz, J(H-7,H-8)=6.7 Hz, J(H-7,H-6)=5.1 Hz, H-7);
4.82 (ddd, J(H-6,NH)=9.1 Hz, J(H-6,H-7)=5.1 Hz, J(H-6,H-5)=1.9 Hz, H-6); 4.64, 4.52
3
3
3
3
3
3
2
2
3
(2d, J=11.9 Hz, CH2(Bn)); 4.48 (s, H-2); 4.26 (dd, J=12.3 Hz, J(H-4,H-5)=3.9 Hz, H-4);
4.01 (m, H-5); 3.86 (s, MeO(PMBz)); 3.82 (s, MeO(PMBz)) 3.68 (d, 2J=12.3 Hz, H-4); 3.53, 3.49
(2d, 2J=9.8 Hz, CH2-C1); 3.44 (s, 3H(MeO)); 2.30 (dd, 2J=14.1 Hz, 3J(H-8,H-7)=6.7 Hz, H-8);
2.23 (dd, J=14.1 Hz, J(H%-8,H-7)=11.3 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz): ꢀ165 (4s,
4Car); 138.7 (s, Car); 131.7, 128.8, 128.4, 127.7, 127.5, 113.8, 113.5 (7d, 13CHar); 98.5 (d, C2);
77.2 (s, C1); 74.8, 73.8, 73.4 (2t+1d, CH2(Bn)+CH2-C1+C5); 72.4, 66.8, 59.1 (2d+1t, C7+C4+
C6); 55.4, 55.3, 49.6 (3q, 3(MeO)); 31.3 (t, C8). CI-MS(NH3): m/z 578 (100, [M+H]+), 546 (6,
[M−OMe]+), 426 (2, [M−PMBzO]+), 204 (3), 135 (11), 102 (4).
2
3
Data for b-21. UV (CH3CN): umax=248 nm (m=17300 [dm3 cm−1 mol−1]), 214 nm (13700). IR
(film): 2925, 1645, 1605, 1495, 1455, 1375, 1255, 1170, 1095, 1025 cm−1. H NMR (CDCl3, 400
1
3
3
MHz): 7.87 (dm, J=8.9 Hz, 2Har); 7.69 (dm, J=9.0 Hz, 2Har); 7.40–7.31 (m, 5H(Ph)); 6.89
3
3
3
(dm, J=9.0 Hz, 2Har); 6.81 (dm, J=8.9 Hz, 2Har); 6.72 (d, J(NH,H-6)=9.1 Hz, NH); 6.14
3
3
3
(ddd, J(H-7,H-8)=11.4 Hz, J(H-7,H-8)=6.3 Hz, J(H-7,H-6)=4.9 Hz, H-7); 4.81 (ddd,
3J(H-6,NH)=9.1 Hz, 3J(H-6,H-7)=4.9 Hz, 3J(H-6,H-5)=1.9 Hz, H-6)); 4.65, 4.57 (2d, 2J=12.1
Hz, CH2(Bn)); 4.63 (s, H-2); 4.01 (br.s, 2H-4); 4.01 (br.s, H-5); 3.86 (s, MeO(PMBz)); 3.82 (s,
2
2
MeO(PMBz)); 3.53, 3.45 (2d, J=10.4 Hz, CH2-C1); 3.49 (s, 3H(MeO)); 2.35 (dd, J=13.2 Hz,
3J(H-8,H-7)=6.3 Hz, H-8); 1.77 (dd, J=13.2 Hz, J(H%-8,H-7)=11.4 Hz, H%-8)). 13C NMR
(CDCl3, 100.6 MHz): ꢀ165 (4s, 4Car); ꢀ140 (s, Car); 131.7, 128.7, 128.4, 127.8, 127.7, 113.8,
113.5 (7d, 15CHar); 101.3 (d, C2); 77.2 (s, C1); 73.8, 73.0, 72.6 (2t+1d, CH2(Bn)+CH2-C1+C5);
66.5, 65.9, 57.9 (2d+1t, C7+C4+C6); 56.6, 55.4, 49.2 (3q, 3(MeO)); 27.5 (t, C8). CI-MS(NH3):
m/z 579 (100), 578 (99, [M+1]+), 546 (1, [M−OMe]+), 426 (5, [M−PMBzO]+), 204 (3), 135 (14).
2
3
4.19. (R)-h-Methoxy-h-(trifluoromethyl)benzylacetic acid (1R,2R,5R,6R,7R)-6-azido-1-
[(benzyloxy)methyl]-2-exo-methoxy-3,9-dioxabicyclo[3.3.1]nonan-7-exo-yl ester ((R)-h-22) and
(R)-h-methoxy-h-(trifluoromethyl)benzylacetic acid (1R,2S,5R,6R,7R)-6-azido-1-[(benzyloxy)-
methyl]-2-endo-methoxy-3,9-dioxabicyclo[3.3.1]nonan-7-exo-yl ester(R)-i-22
(S)-(+)-a-Methoxy-a-(trifluoromethyl)-a-phenylacetyl chloride (34 mL, 0.18 mmol) and
DMAP (catalytic amount) were added to a (1.7:1) soln of a-19/b-19 (30 mg, 0.09 mmol) in
pyridine (1 mL) stirred at 20°C. After 3 h 30 min, the mixture was treated with H2O (1 mL). The
aq. phase was extracted with Et2O (10 mL, four times). The combined org. extracts were dried
(MgSO4) and concentrated. FC (silica gel, EtOAc/light petroleum ether (1:2), Rf=0.51) afforded
a (1.6:1) mixture of (R)-a-22/(R)-b-22 (37 mg, 75%), colorless oil. [h]25859=55, [h]52757=47,
[h]52546=54, [h]24355=93, [h]42053=113 (c=0.6, CHCl3). UV (CH3CN): umax=213 nm (m=6600 [dm3
cm−1 mol−1]). IR (film): 2935, 2865, 2105, 1750, 1495, 1455, 1355, 1260, 1185, 1170, 1125, 1095,

4678
F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
1075, 1020, 1000, 910, 825, 735, 700 cm−1. CI-MS (NH3): m/z 569 (100, [M+NH4]+), 524 (3,
[M+H−N2]+), 520 (3.4, [M−OMe]+), 189 (23), 156 (6), 91 (32). Anal. calcd for C26H28F3N3O7
1
(551.52): C, 56.62; H, 5.12; N, 7.62. Found: C, 56.52; H, 5.24; N, 7.51. H NMR (CDCl3, 400
2
MHz) of (R) a-22: 7.63–7.27 (m, 10H(Ph)); 6.10–6.02 (m, H-7); 4.57, 4.44 (2d, J=12.1 Hz,
2
3
CH2(Bn)); 4.47 (s, H-2); 4.24 (dd, J=12.3 Hz, J(H-4,H-5)=3.7 Hz, H-4); 4.09–4.05 (m, H-5);
2
2
4.00–3.96 (m, H-6); 3.62 (br.s, 3H(MeO)); 3.55, 3.32 (2d, J=9.1 Hz, CH2-C1); 3.51 (d, J=12.3
2
3
Hz, H%-4); 3.42 (s, 3H(MeO)); 2.16 (dd, J=13.8 Hz, J(H-8,H-7)=6.6 Hz, H-8); 2.11 (dd,
2J=13.8 Hz, 3J(H%-8,H-7)=11.3 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz) of (R)-a-22: 166.1 (s,
1
COO); 137.9 (s, Car); 131.9 (s, Car); 129.7–127.3 (6d, J=159–162 Hz, 10CHar); 123.2 (q,
1JC-F=289 Hz, CF3); 98.3 (d, J=169 Hz, C2); 84.5 (s, C(Ph)(CF3)(OMe)(COOR)); 74.4 (s, C1);
1
1
1
1
73.6 (t, J=141 Hz, CH2(Bn)); 73.2 (t, J=144 Hz, CH2-C1); 71.7 (d, J=147 Hz, C5); 70.5 (d,
1J=155 Hz, C7); 60.8 (d, J=147 Hz, C6); 58.8 (t, J=148 Hz, C4); 55.4 (2q, J=143 Hz,
1
1
1
1
1
2MeO); 31.3 (t, J=133 Hz, C8). H NMR (CDCl3, 400 MHz) of (R)-b-22: 7.63–7.27 (m,
10H(Ph)); 6.10–6.02 (m, H-7); 4.72 (s, H-2); 4.65, 4.50 (2d, 2J=12.4 Hz, CH2(Bn)); 4.09–4.05 (m,
2
H-5); 4.07, 3.90 (2d, J=11.5 Hz, 2H-4); 4.00–3.96 (m, H-6); 3.60 (br.s, 3H(MeO)); 3.48 (s,
2
2
3
3H(MeO)); 3.45, 3.34 (2d, J=10.6 Hz, CH2-C1); 2.08 (dd, J=13.5 Hz, J(H-8,H-7)=6.8 Hz,
H-8); 1.68 (dd, J=13.5 Hz, J(H%-8,H-7)=12.3 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz) of
2
3
1
(R)-b-22: 165.9 (s, COO); 137.8 (s, Car); 131.9 (s, Car); 129.7–127.3 (6d, J=159–162 Hz,
10CHar); 123.2 (q, 1JC-F=289 Hz, CF3); 101.1 (d, 1J=163 Hz, C2); 84.8 (s,
1
1
C(Ph)(CF3)(OMe)(COOR)); 76.2 (s, C1); 73.7 (t, J=141 Hz, CH2(Bn)); 72.7 (t, J=142 Hz,
1
1
1
CH2-C1); 71.9 (d, J=149 Hz, C5); 70.4 (d, J=155 Hz, C7); 65.7 (t, J=145 Hz, C4); 60.0 (d,
1J=144 Hz, C6); 56.8, 55.4 (2q, J=143 Hz, 2MeO); 27.0 (t, J=133 Hz, C8).
1
1
4.20. (S)-h-Methoxy-h-(trifluoromethyl)benzylacetic acid (1R,2R,5R,6R,7R)-6-azido-1-
[(benzyloxy)methyl]-2-exo-methoxy-3,9-dioxabicyclo[3.3.1]nonan-7-exo-yl ester ((S)-h-22) and
(S)-h-methoxy-h-(trifluoromethyl)benzylacetic acid (1R,2S,5R,6R,7R)-6-azido-1-[(benzyloxy)-
methyl]-2-endo-methoxy-3,9-dioxabicyclo[3.3.1]nonan-7-exo-yl ester (S)-i-22
Same procedure as above, starting from (R)-(−)-a-methoxy-a-(trifluoromethyl)-a-phenylacetyl
chloride. It affords a 1.66:1 mixture of (S)-a-22/(S)-b-22 (46 mg, 85%), colorless oil. [h]25859=−19,
[h]52577=−18, [h]52546=−21, [h]42355=−34, [h]24053=−39 (c=0.34, CHCl3). UV (CH3CN): umax=209 nm
(m=10900 [dm3 cm−1 mol−1]). IR (film): 2935, 2865, 2105, 1750, 1495, 1455, 1355, 1260, 1170,
1075, 1020, 915, 825, 735, 725, 620 cm−1. CI-MS(NH3): m/z 569 (100, [M+NH4]+), 524 (5,
[M+H−N2]+), 520 (5, [M−OMe]+), 189 (31), 156 (25), 91 (47). Anal. calcd for C26H28F3N3O7
1
(551.52): C, 56.62; H, 5.12; N, 7.62. Found: C, 56.64; H, 5.17; N, 7.55. H NMR (CDCl3, 400
2
MHz) of (S)-a-22: 7.63–7.27 (m, 10H(Ph)); 6.12–6.04 (m, H-7); 4.59, 4.46 (2d, J=12.1 Hz,
2
3
CH2(Bn)); 4.48 (s, H-2); 4.22 (dd, J=12.3 Hz, J(H-4,H-5)=3.7 Hz, H-4); 4.09–4.02 (m, H-5);
2
2
3.90–3.86 (m, H-6); 3.61 (br.s, 3H(MeO)); 3.57, 3.35 (2d, J=9.1 Hz, CH2-C1); 3.49 (d, J=12.3
2
3
Hz, H%-4); 3.42 (s, 3H(MeO)); 2.28 (dd, J=13.5 Hz, J(H-8,H-7)=6.3 Hz, H-8); 2.19 (dd,
2J=13.5 Hz, 3J(H%-8,H-7)=11.7 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz) of (S)-a-22: 166.0 (s,
COO); 137.9 (s, Car); 131.9 (s, Car); 129.7–127.2 (6d, 1J=159–162, 10CHar); 123.2 (q,
1JC-F=289 Hz, CF3); 98.3 (d, J=168 Hz, C2); 84.4 (s, C(Ph)(CF3)(OMe)(COOR)); 74.4 (s, C1);
1
1
1
1
73.6 (t, J=142 Hz, CH2(Bn)); 73.2 (t, J=145 Hz, CH2-C1); 71.7 (d, J=148 Hz, C5); 70.6 (d,
1J=152 Hz, C7); 60.9 (d, J=142 Hz, C6); 58.8 (t, J=145 Hz, C4); 55.5 (2q, J=145 Hz,
1
1
1
1
1
2MeO); 31.5 (t, J=131 Hz, C8). H NMR (CDCl3, 400 MHz) of (S)-b-22: 7.63–7.27 (m,
10H(Ph)); 6.12–6.04 (m, H-7); 4.72 (s, H-2); 4.66, 4.51 (2d, 2J=12.4 Hz, CH2(Bn)); 4.09–4.02 (m,

F. Carrel, P. Vogel / Tetrahedron: Asymmetry 11 (2000) 4661–4680
4679
2
H-5+H-4); 3.90–3.86 (m, H%-4+H-6); 3.60, 3.49 (2s, 6H(MeO)); 3.47, 3.36 (2d, J=10.6 Hz,
2
3
2
3
CH2-C1); 2.18 (dd, J=12.9 Hz, J(H-8,H-7)=6.5 Hz, H-8); 1.76 (dd, J=12.9, J(H%-8,H-7)=
12.2 Hz, H%-8). 13C NMR (CDCl3, 100.6 MHz) of (S)-b-22: 165.8 (s, COO); 137.8 (s, Car); 131.9
1
1
(s, Car); 129.7–127.2 (6d, J=159–162 Hz, 10CHar); 123.2 (q, JC-F=289 Hz, CF3); 100.9 (d,
1J=165 Hz, C2); 84.7 (s, C(Ph)(CF3)(OMe)(COOR)); 76.2 (s, C1); 73.7 (t, 1J=141 Hz,
1
1
1
CH2(Bn)); 72.7 (t, J=144 Hz, CH2-C1); 71.9 (d, J=150 Hz, C5); 70.4 (d, J=152 Hz, C7);
1
1
1
65.7 (t, J=145.0, C4); 60.1 (d, J=145 Hz, C6); 56.8, 55.5 (2q, J=144 Hz, 2MeO); 27.2 (t,
1J=132 Hz, C8).
Acknowledgements
This work was supported by the Swiss National Science Foundation (Grant no. 20-55567.98)
and by Office Fe´de´ral de l’Education et de la Science (European COST D13 project No
0001/1999).
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