Oligosaccharide analogues of polysaccharides. Part 23: Synthesis of a dimeric acetyleno cyclodextrin from a mannopyranose-derived dialkyne

Article abstract of DOI:10.1002/1522-2675(20010815)84:8<2355::AID-HLCA2355>3.0.CO;2-X

The 1,4-cis-diethynylated α-D-mannopyranose analogue 11 has been prepared from 1,6:2,3-dianhydro-β-D-allopyranose (6) by alkynylating epoxide and acetal opening (Scheme 2). Eglinton coupling of 11 gave the cyclodimer 18 (Scheme 3). Crystal-structure analysis of the corresponding bis(methanesulfonate) 19 revealed substantially bent butadiyne moieties; one mannopyranosyl ring adopts the ⁴C₁ and the other one a slightly distorted ^oS₂ conformation (Fig. 1). Hydrogenation of 18, followed by deprotection, gave the stable butane-1,4-diyl-bridged cyclodimer 21 (Scheme 3). Crystal-structure analysis shows the ⁴C₁ conformation of the mannopyranosyl units (Fig. 2). The two butane fragments are characterised by a combination of gauche and antiperiplanar arrangements.

Full text of DOI:10.1002/1522-2675(20010815)84:8<2355::AID-HLCA2355>3.0.CO;2-X

Helvetica Chimica Acta ± Vol. 84 (2001)
2355
Oligosaccharide Analogues of Polysaccharides
Part 231)
Synthesis of a Dimeric Acetyleno Cyclodextrin from a Mannopyranose-Derived
Dialkyne
by Jürgen Stichler-Bonaparte and Andrea Vasella*
Laboratorium für Organische Chemie, ETH-Zürich, Universitätstrasse 16, CH-8092 Zürich
Â
Dedicated to Gerard Descotes
The 1,4-cis-diethynylated a-d-mannopyranose analogue 11 has been prepared from 1,6 :2,3-dianhydro-b-d-
allopyranose (6) by alkynylating epoxide and acetal opening (Scheme 2). Eglinton coupling of 11 gave the
cyclodimer 18 (Scheme 3). Crystal-structure analysis of the corresponding bis(methanesulfonate) 19 revealed
substantially bent butadiyne moieties; one mannopyranosyl ring adopts the 4C1 and the other one a slightly
distorted OS2 conformation (Fig. 1). Hydrogenation of 18, followed by deprotection, gave the stable butane-1,4-
diyl-bridged cyclodimer 21 (Scheme 3). Crystal-structure analysis shows the 4C1 conformation of the
mannopyranosyl units (Fig. 2). The two butane fragments are characterised by a combination of gauche and
antiperiplanar arrangements.
Introduction. ± In the context of the synthesis of alkynylated saccharides, we have
so far prepared up to hexadecameric cellulose analogues where the glycosidic O-atom
is replaced by a butadiyne group, interrupting intramolecular, inter-residue H-bonds so
as to evaluate their contribution to the supramolecular structure of cellulose (see [2]
and earlier publications cited there). For this, we have synthesised glucopyranose
derivatives possessing 1,4-trans-oriented ethynyl substituents [3][4]. We have also
synthesised the isomeric a-d-glucopyranose analogues, possessing 1,4-cis-oriented
ethynyl substituents [5]. These have been incorporated in cyclotrimeric, cyclotetra-
meric, and cyclohexameric analogues of cyclodextrins [6]. Remarkably, oxidative
oligomerisation of the dialkyne 1 has led in a single step to the C1-symmetric
cyclotrimer 2 (Scheme 1), while the larger cyclooligomers were prepared by selective
cross-coupling. We have also used 4-, or 1-monoethynylated glucopyranose derivatives
to transform maltohexaose derivatives to maltooctaoses possessing terminal ethynyl
groups, and further to cyclomaltooctaose analogues, in which a butadiyne-1,4-diyl
group is replaced by one glycosidic O-atom [1].
In the course of the synthesis of these acetyleno sugars, we have devised methods
for the invertive [5] or retentive [3] alkynylating opening of 1,6-anhydro-b-d-
glucopyranoses, providing a rapid access to a- or b-d-glucopyranosyl-acetylenes. It
was tempting to also prepare the analogous branched chain a-d-mannopyranosyl-
acetylene and to examine its oxidative cyclooligomerisation. A few mannopyranosyl-
acetylenes have been prepared [7 ± 10]. Reductive dehydroxylation of an ulose
1
)
For part 22, see [1].

2356
Helvetica Chimica Acta ± Vol. 84 (2001)
Scheme 1
precursor led mostly to b-d-mannopyranosyl-acetylene [7]. Isobe and co-workers [8]
have described an advantageous route to an a-d-mannopyranosyl-acetylene involving
the TMSOTf-promoted reaction of an a-d-mannopyranosyl acetate with 2-(tributyl-
stannyl)-1-(trimethylsilyl)acetylene, while 1,2-bis(trimethylsilyl)acetylene did not lead
to the formation of mannopyranosyl-acetylenes. This observation, and the desire to
prepare the unknown deprotected a-d-mannopyranosyl-acetylene prompted us to also
examine the alkynylating ring opening of a fully O-substituted 1,6-anhydro-b-d-
mannopyranose.
Results and Discussion. ± The required branched chain a-d-mannopyranosyl-
acetylenes 11 and 12 were prepared from the known 1,6 :2,3-dianhydro-b-d-talopyr-
anose (6) [11] (Scheme 2). Its preparation from the acetonide 3 [12] via the
methanesulfonates 4 and 5 proved faster and higher yielding (82% on a 20-g scale)
than the procedures involving the analogous tosylates [11][13][14]. Silylation of 6 to 7,
followed by trans-diaxial opening of the oxirane ring with lithium (trimethylsilyl)ace-
tylide (LiTMSA) in the presence of AlMe3 gave selectively the ethynylated 1,6-
anhydromannopyranose 8. Silylation of 8 with (i-Pr)3SiCl (TIPSCl) in pyridine failed
even at elevated temperature (808), presumably on account of the intramolecular H-
bond (see below) and the shielding by the TIPSO C(2) group, while silylation with
TIPSOTf in pyridine at 808 for 24 h yielded 90% of 9. Treatment of 9 with LiTMSA in
the presence of AlCl3 gave selectively the a-d-mannopyranosyl-acetylene 10 (81%).
Removal of the Me3Si groups by treatment of 10 with MeONa in MeOH provided 11.
The OTIPS groups were cleaved by treatment with aqueous TFA to yield the desired
branched chain a-d-mannopyranosyl-acetylene 12 in 43% yield from 3.
To prepare the axial ethynyl C-mannopyranoside 16, we silylated commercial 1,6-
anhydro-b-d-mannopyranose (13) with TIPSOTf and pyridine in (Cl2CH)2 at 1108 to
obtain 92% of 14 (Scheme 2). Treatment of 14 with 10 equiv. of LiTMSA and AlCl3 led
selectively to the a-d-mannopyranosyl-acetylene 15 (83%). It was deprotected by
sequential treatment with aqueous TFA and NaOMe in MeOH to 16 that is thus
available in three steps and an overall yield of 58% from 1,6-anhydro-b-d-
mannopyranose (13).
The (trimethylsilyl)acetylene group of 8 is evidenced by the IR alkyne band at 2178 cm 1, three new
resonances in the 13C-NMR spectrum at 0.04, 87.53, and 104.31 ppm, and the Me3Si signal at 0.15 ppm in the
1H-NMR spectrum. H C(4) of 8 is unambiguously assigned by homodecoupling experiments, irradiation of

Helvetica Chimica Acta ± Vol. 84 (2001)
2357
Scheme 2
a) MsCl, Et3N, CH2Cl2; 88%. b) AcOH/H2O 1 :4; 93%. c) NaOMe, MeOH; 96% (6), 98% (11), 76% (16). d)
TIPSOTf, pyridine/CH2Cl2, 238; 99%. e) Me3SiCꢀCLi, AlMe3, toluene/THF; 85% (8), 81% (10), 83% (15). f)
TIPSOTf, pyridine, 808; 90%. g) THF/CF3COOH/H2O 2 :1:1; 92%. h) TIPSOTf, pyridine/(Cl2CH)2; 92%.
H
C(5) and H C(3), leading to sharpening of the H C(4) signal. This signal appears at higher field than
those of H C(2) and H C(3) (3.00 vs. 3.97 and 4.11 ppm), evidencing the attachment of the ethynyl moiety at
C(4). H C(3) of 8 resonates at 4.11 ppm as a dquint., showing a coupling of 4.8 Hz with the cis-oriented
H
C(2) and couplings of ca. 1.6 Hz with the trans-oriented H C(2), with H C(1) and H C(5) (W couplings),
and with OH. These couplings evidence the manno-configuration and the 1C4 conformation. The small J(3,OH)
value reveals that HO C(3) forms a H-bond to O C(2) and not to O C(6), since J(3,OH) for HO C(3) to
O
C(6) H-bonded 1,6-anhydro-b-d-glucopyranoses amounts to ca. 7.0 Hz [15]. The 4C1 conformation of the
manno-configured 10 ± 12 is evidenced by large J(2,3) and J(3,4) values (>10 Hz), and a small J(4,5) value
(2.2 ± 3.0 Hz). The dialkyne 10 shows an OH signal at 2.01 ppm and a br. IR band at 3499 cm 1. The upfield shift
of the C(1) t at 64.3 ppm evidences a free primary OH group and, thus, the cleavage of the acetal. The signals of
the two Me3Si moieties of 10 appear in the 1H-NMR spectrum at 0.13 and 0.18 ppm, and in the 13C-NMR
spectrum at 0.31 and 0.25 ppm. Characteristic shifts are observed for the ethynyl C-atoms of 10; 95.02 and
105.12 ppm are typical for an equatorial nonanomeric Me3SiCꢀC group, and 89.02 and 100.00 ppm typical for
an axial anomeric Me3SiCꢀC group (cf. [5][6]). Desilylation leads to an upfield shift for the HCꢀC signals of
11 and 12; 82.7 ± 83.0 and 72.9 ± 73.1 ppm for the equatorial HCꢀC group, and 75.5 ± 79.4 for the axial HCꢀC
group. The a-d-configuration of the mannopyranosyl-acetylenes 10 and 11 is evidenced by the downfield shift of
H
H
C(2) at 3.86 ± 3.89 ppm and of H C(4) at 4.41 ppm, as compared to the chemical shifts of H C(2) and
C(4) of related b-d-glucopyranosyl-acetylenes (3.3 ± 3.6 ppm) [3]. In agreement with this assignment, the
monoalkynes 15 and 16 show the typical 13C-NMR chemical shifts for an axial anomeric acetylene group (15:
90.8 and 104.4 ppm; 16: 78.7 and 79.7 ppm).

2358
Helvetica Chimica Acta ± Vol. 84 (2001)
Scheme 3
a) Ca. 1 mm 11, Cu(OAc)2, pyridine, 238; 77%. b) Ca. 1 mm 17, Cu(OAc)2, pyridine, 1008; 71% from 17, 65%
from 11. c) MsCl, pyridine/CH2Cl2; 99%. d) H2, Pd/C, AcOH; 79%. f) TBAF on silica gel, THF; 97%.
Oxidative treatment of the deprotected dialkyne 12 under similar conditions as
used for the cyclotrimerisation of 1 (Cu(OAc)2 in pyridine at 238 [6]) resulted in a
complex mixture, while the analogous treatment of the TIPS-protected dialkyne 11 led
within 2 h at 238 in a yield of 77% to the crystalline dimer 17 (Scheme 3). It proved
inert to these reaction conditions, but reacted with Cu(OAc)2 in pyridine at 1008 to
form the cyclodimer 18 (71%) that was also obtained by the analogous one-pot
oxidation of the monomer 11 (65%). Attempts to remove the TIPS groups of 18 by
treatment with Bu4NF ´ 3 H2O, NEt3 ´ HF, pyridine ´ HF, and NBS/DMSO [16 ± 18] gave
complex mixtures. The cyclodimer 18 undergoes an irreversible exothermic transition
of 63 kcal/mol (DSC) in the broad temperature range of 185 ± 2508 (without formation
of volatile products), and decomposed during storage at 238 within several days, while
17 showed only an endothermic transition at 1188 (melting). Mesylation of 18 yielded
the bis(methanesulfonate) 19 that crystallized from pentane. Pd-Catalysed hydro-
genation of 18 in AcOH gave the bis(butane-1,4-diyl)-bridged dimer 20 (79%), which
was deprotected with TBAF to 21. Both the TIPS-protected cyclodimer 20 and the
correponding hexol 21 are thermally stable, melting without decomposition between
218 ± 2208 and 212 ± 2138, respectively.
The X-ray crystal structure of 192) showed bent buta-1,3-diyne moieties evidenced
by C(sp3) CꢀC and CꢀC C(sp) bond angles of 167 and 170.58, respectively, for the
2
)
The crystallographic data have been deposited with the Cambridge Crystallographic Data Centre as
deposition No. CCDC-166391 (19) and CCDC-166392 (21 ´ MeOH). Copies of the data can be obtained,
free of charge, on application to the CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax: ‡44(1223)336033;
e-mail: deposit@ccdc.cam.ac.uk).

Helvetica Chimica Acta ± Vol. 84 (2001)
2359
buta-1.3-diyne group between C(1) and C(1'), and by C(sp3) CꢀC and CꢀC C(sp)
bond angles of 159 ± 160 and 1658, respectively, for the buta-1,3-diyne group between
C(4) and C(4') (Fig. 1 and Table 1). The CꢀC and C(sp) C(sp) bond lengths (1.197 Æ
0.007 and 1.383 Æ 0.008 Š, resp.) show no deviation from the standard values observed
in bent or linear conjugated dialkynes3) (for similar observations for strained
Fig. 1. Crystal structure of the bis(buta-1,3-diyne-1,4-diyl)-bridged cyclodimer 19
Table 1. Selected Bond Lengths, Atom Distances, and Bond and Dihedral Angles of the X-Ray Structure of 19
Bond length or atom distance [Š]
Bond or dihedral angle [8]
C(1) C(2)
C(2) C(3)
C(3) C(4)
C(4) C(5)
C(5) O(5)
O(5) C(1)
C(1') C(2')
C(2') C(3')
C(3') C(4')
C(4') C(5')
C(5') O(5')
O(5') C(1')
1.544(4)
1.524(4)
1.553(4)
1.558(4)
1.418(4)
1.427(4)
1.570(5)
1.525(4)
1.556(4)
1.558(4)
1.420(4)
1.438(3)
C(1) C(1'')
C(1'')ꢀC(2'')
C(2'') C(3'')
C(3'')ꢀC(4'')
C(4'') C(1')
C(4) C(1''')
C(1''')ꢀC(2''')
C(2''') C(3''')
C(3''')ꢀC(4''')
C(4''') C(4')
1.474(4)
1.195(4)
1.391(4)
1.192(4)
1.472(4)
1.466(4)
1.203(4)
1.375(4)
1.201(4)
1.469(4)
C(1) C(1'')ꢀC(2'')
167.0(3)
170.3(4)
170.5(4)
167.1(4)
160.0(3)
164.7(4)
165.6(4)
159.3(3)
55.7
48.1
48.1
57.3
63.7
62.5
61.9
40.9
21.4
69.2
46.7
18.9
C(1'')ꢀC(2'') C(3'')
C(2'') C(3'')ꢀC(4'')
C(3'')ꢀC(4'')C (1')
C(4) C(1''')ꢀC(2''')
C(1''')ꢀC(2''') C(3''')
C(2''') C(3''')ꢀC(4''')
C(3''')ꢀC(4''') C(4')
C(1) C(2) C(3) C(4)
C(2) C(3) C(4) C(5)
C(3) C(4) C(5) O(5)
C(4) C(5) O(5) C(1)
C(5) O(5) C(1) C(2)
O(5) C(1) C(2) C(3)
C(1') C(2') C(3') C(4')
C(2') C(3') C(4') C(5')
C(3') C(4') C(5') O(5')
C(4') C(5') O(5') C(1')
C(5') O(5') C(1') C(2')
O(5') C(1') C(2') C(3')
C(1) ´´´ C(1')
C(2) ´´´ O(5')
C(3) ´´´ C(5')
C(4) ´´´ C(4')
C(5) ´´´ C(3')
O(5) ´´´ C(2')
6.468
7.283
5.650
6.113
6.588
6.594
C(1) ´´´ C(4)
2.911
4.254
4.748
4.745
4.267
2.962
C(1'') ´´´ C(1''')
C(2'') ´´´ C(2''')
C(3'') ´´´ C(3''')
C(4'') ´´´ C(4''')
C(1') ´´´ C(4')
3
)
Many bent cyclic butadiynes have been prepared by Glaser, Hay, and Eglinton coupling [19][20]. More
than 15 structures possessing similar bent buta-1,3-diynyl groups are deposited with the Cambridge
Crystallographic Data Centre; typical representatives are cyclododecadiynes or -tetraynes [21 ± 24].

2360
Helvetica Chimica Acta ± Vol. 84 (2001)
cylcoalkynes, see [19][20]). One of the tetrahydropyran rings of 19 adopts the 4C1, the
other a slightly distorted OS2 conformation, showing that ring strain is affecting both the
linearity of the buta-1,3-diyne groups and the ring conformation. The butadiyne units of
19 lie almost in one plane and form a very small elliptical cavity, with C(1) ´´´ C(1'),
C(4) ´´´ C(4'), C(2'') ´´´ C(2'''), and C(3'') ´´´ C(3''') distances of 6.468, 6.113, 4.748, and
4.745 Š, respectively.
In the solid state, both tetrahydropyran rings of 21 ´ MeOH (Fig. 2 and Table 2)2)
adopt a 4C1 conformation, evidencing a strongly decreased ring strain as compared with
the bis(buta-1,4-diyne) 19. As best seen in the top view (Fig. 2,b), the butane moiety
between C(4) and C(4') adopts an antiperiplanar arrangement for the central
Fig. 2. Crystal structure of the bis(butane-1,4-diyl)-bridged cyclodimer 21 ´ MeOH adduct: a) front view and
b) top view
Table 2. Selected Bond Lengths, Atom Distances, and Dihedral Angles of the X-Ray Structure of 21 ´ MeOH
Bond length or atom distance [Š]
Dihedral angle [8]
C(1) C(2)
C(2) C(3)
C(3) C(4)
C(4) C(5)
C(5) O(5)
O(5) C(1)
C(1') C(2')
C(2') C(3')
C(3') C(4')
C(4') C(5')
C(5') O(5')
O(5') C(1')
C(1) ´´´ C(1')
C(2) ´´´ O(5')
C(3) ´´´ C(5')
C(4) ´´´ C(4')
C(5) ´´´ C(3')
O(5) ´´´ C(2')
1.523(3)
1.520(3)
1.527(3)
1.526(3)
1.435(3)
1.437(3)
1.523(3)
1.520(3)
1.525(4)
1.535(3)
1.437(3)
1.437(3)
5.569
C(1) C(1'')
C(1'') C(2'')
C(2'') C(3'')
C(3'') C(4'')
C(4'') C(1')
C(4) C(1''')
C(1''') C(2''')
C(2''') C(3''')
C(3''') C(4''')
C(4''') C(4')
1.522(3)
1.527(4)
1.538(3)
1.537(3)
1.523(3)
1.541(3)
1.535(4)
1.530(3)
1.533(4)
1.544(3)
C(1) C(2) C(3) C(4)
C(2) C(3) C(4) C(5)
C(3) C(4) C(5) O(5)
C(4) C(5) O(5) C(1)
C(5) O(5) C(1) C(2)
O(5) C(1) C(2) C(3)
C(1') C(2') C(3') C(4')
C(2') C(3') C(4') C(5')
C(3') C(4') C(5') O(5')
C(4') C(5') O(5') C(1')
C(5') O(5') C(1') C(2')
O(5') C(1') C(2') C(3')
C(1) C(1'') C(2'') C(3'')
C(1'') C(2'') C(3'') C(4'')
C(2'') C(3'') C(4'') C(1')
C(4) C(1''') C(2''') C(3''')
C(1''') C(2''') C(3''') C(4''')
C(2''') C(3''') C(4''') C(4')
49.1
47.6
51.3
59.6
59.9
53.3
57.5
54.4
52.6
56.1
56.6
56.1
156.1
81.2
C(1) ´´´ C(4)
2.935
4.873
5.923
5.803
4.808
2.924
6.227
4.863
4.905
5.790
C(1'') ´´´ C(1''')
C(2'') ´´´ C(2''')
C(3'') ´´´ C(3''')
C(4'') ´´´ C(4''')
C(1') ´´´ C(4')
152.7
100.5
179.9
91.3
6.178

Helvetica Chimica Acta ± Vol. 84 (2001)
2361
CH2 CH2 bond (dihedral angle of 1808) bond and a gauche arrangement for the
peripheral CH2 CH2 bonds ( 100 and 918), while the butane moiety between C(1)
and C(1') adopts a gauche arrangement for the central CH2 CH2 bond (dihedral angle
of 818) and an antiperiplanar arrangement for the peripheral CH2 CH2 bonds ( 156
and 1538). These gauche orientations may indicate some strain in the 16-membered
ring. The planes through the mannopyranosyl units are nearly parallel (C(1) ´´´ C(1') ˆ
5.569 Š, C(4) ´´´ C(4') ˆ 6.178 Š). The OH groups of 21 are engaged in intermolecular
H-bonds, HO C(6') as donor to MeOH.
The expected signals for the Na-adducts are observed in the ESI mass spectrum of the dimer 17 at m/z 1038
and in the MALDI-TOF mass spectrum of the cyclodimer 18 at m/z 1036. A single set of signals in the 1H- and
13C-NMR spectra of 17 and 18 evidences the (averaged) C2-symmetry of these dimers. The IR absorption for
HCꢀC at 3315 cm 1, the Raman transition for an isolated HCꢀC bond at 2120 cm 1, and the HCꢀC d at
1
2.11 ppm evidence the acyclic structure of 17. The Raman band of 17 at 2248 cm indicates a buta-1,3-diyne
1
group (typical range for dialkynylated buta-1,3-diynes: 2251 ± 2265 cm [25]). The formation of the
bis(mannopyranosyl) butane 17 is evidenced by the H C(1) d at 4.72 ppm (J ˆ 2.2 Hz), the H C(4) td (J ˆ
10.2, 2.2 Hz). The 13C-NMR signals at 82.4 and 73.1 ppm confirm the HCꢀC C(4) moiety. The buta-1,3-diyne
group resonates at 72.8 and 75.3 ppm, typical for bis(hexopyranosyl)-buta-1,3-diynes [6]. The disappearance of
the H CꢀC signal at 2.11 ppm and the IR band at 3315 cm 1 indicate an alkyne-alkyne coupling to 18. The ring
1
strain of 18 is evidenced by a shift towards lower wavenumbers [19][20] of the Raman transition (2230 cm
,
1
compare with 2234 cm for a similarly strained cyclododeca-1,3,7,9-tetrayne [26]) and by a downfield shift [19 ±
21] of the s for the buta-1,3-diyne groups resonating at 70.6, 75.2, 78.5, and 92.8 ppm. The vicinal couplings
J(1,2) ˆ 3.4, J(2,3) ˆ 3.0, J(3,4) ˆ 7.5, and J(4,5) ˆ 7.8 Hz agree with a ca. 1:1 contribution of the 4C1 and OS2
conformer. Mesylation has no influence upon the ring strain, as 19 shows similar vicinal J(H,H) and similar d
values for the buta-1,3-diyne moiety as 18.
The C2 symmetry of the butanes 20 and 21 is evidenced by a single set of signals in the 1H- and 13C-NMR
spectra. The butane fragments are revealed in 13C-NMR spectrum by 4 t between 24.2 and 30.6 ppm. The vicinal
couplings of 20 (J(1,2) ˆ 2.1, J(2,3) ˆ 2.4, and J(3,4) ˆ 10.5 Hz) evidence the 4C1 conformation (signal
overlapping prevented the determination of J(4,5)). The hexol 21, however, shows clearly different couplings
(3.4 and 5.5 Hz for J(1,2) and J(2,3), resp., and 6.5 Hz for J(4,5)), suggesting an equilibrium between 4C1 and OS2
conformers. H-Bonding of HO C(6) in CD3OD leads to broad signals for both H C(6) at room temperature.
This broadening disappears at 558 and at 808. The H-bonding has no influence upon the chair/boat
equilibrium, since the vicinal couplings do not change. At 808, a single set of 1H-NMR signals is still observed.
In the 13C-NMR spectrum, broad lines are observed for the signal for C(1)/C(3) and C(5), both at 23 and 558.
We thank the Swiss National Science Foundation, the Fonds der Chemischen Industrie, Frankfurt, and F.
Hoffmann La Roche AG, Basel for generous support. We also thank Dr. P. Seiler for the crystal-structure
determinations, M. Colussi and Prof. Dr. R. Prins for the DSC experiments, and Dr. Bruno Bernet for checking
the data, critical comments, and corrections.
Experimental Part
General. See [3]. Raman spectra were measured on a Perkin-Elmer NIR-FT-spectrometer; excitation by
NdYAG-Perkin-Elmer continous-wave laser (1064 nm). The assignment of 13C-NMR multiplets is based on
DEPT spectra; due to the characteristic J(C,H) coupling, CꢀCH appears as a very weak positive signal, whereas
CꢀCH gives no DEPT signal. Both these signal were assigned as s; see also [27].
1,6-Anhydro-2,3-O-isopropylidene-4-O-(methylsulfonyl)-b-d-mannopyranose (4). MsCl (6.54 ml,
83 mmol) was added dropwise at 38 to a soln. of 3 [12] (12.1 g, 59 mmol) and Et3N (13.2 ml, 94 mmol) in
CH2Cl2 (250 ml). The mixture was stirred for 30 min at 228, poured on ice (200 g), stirred for 2 h, and extracted
with CH2Cl2. The combined org. layers were filtered through cotton and evaporated at 12 mbar and 208. The
slightly yellow solid (15.1 g) was dissolved in AcOEt. Filtration through silica gel (80 g, hexane/AcOEt 1:1) and
crystallisation from hexane/CH2Cl2 2 :1 gave 4 (14.5 g, 88%). White solid. Rf (toluene/AcOEt 1:1) 0.46. M.p.
130 ± 1318 (dec.). IR (KBr): 3044m, 3029m, 2983m, 2945m, 1400w, 1369m, 1330s, 1310m, 1246m, 1219s, 1174s,
1148s, 1112m, 1074s, 990s, 953s, 920m, 896m, 872m, 832s, 798m, 773w. 1H-NMR (500 MHz, CDCl3): 1.33, 1.54 (2s,

2362
Helvetica Chimica Acta ± Vol. 84 (2001)
Me2C); 3.15 (s, MsO); 3.80 (dd, J ˆ 7.7, 6.4, Hexo C(6)); 4.03 (dd, J ˆ 7.7, 1.4, Hendo C(6)); 4.11 (dd, J ˆ 6.3, 3.0,
H
C(2)); 4.31 (dq, J ꢁ 6.3, 1.2, H C(3)); 4.73 (dq, J ˆ 6.4, 1.2, H C(5)); 4.74 (br. s, H C(4)); 5.38 (br. d, J ˆ
3.0, H C(1)). 13C-NMR (125 MHz, CDCl3, assignment based on a HSQC.GRASP spectrum): 25.76, 25.83
(2q, Me2C); 38.79 (q, MsO); 64.27 (t, C(6)); 71.81 (d, C(2)); 73.70 (d, C(4)); 73.86 (d, C(5)); 75.62 (d, C(3));
‡
99.13 (d, C(1)); 110.66 (s, Me2C). EI-MS: 265 (44, [M Me] ), 127 (20), 100 (28), 97 (32), 85 (55), 81 (39), 69
(25), 59 (30), 43 (100). Anal. calc. for C10H16O7S (280.30): C 42.85, H 5.75, S 11.44; found: C 42.79, H 5.71,
S 11.59.
1,6-Anhydro-4-O-(methylsulfonyl)-b-d-mannopyranose (5). A suspension of 4 (17.5 g, 62.4 mmol) in aq.
AcOH/H2O 1:4 (500 ml) was heated under reflux for 1 h. After evaporation of the resulting soln. at 12 mbar
and 408, dissolution in AcOEt, and filtration through silica gel (20 g, AcOEt) gave 5 (14.0 g, 93%). White solid.
Rf (AcOEt) 0.25. M.p. 144 ± 1458 (dec.). IR (KBr): 3437s, 3356s, 3026m, 2978m, 2940m, 2907m, 1478m, 1440m,
1
1423m, 1317s (br.), 1265m, 1121s, 1079s, 1035s, 988s, 958s (br.), 892s, 861s, 838s, 807s, 789m, 730m. H-NMR
(400 MHz, (D6)DMSO): 3.38 (s, MsO); 3.44 (dd, J ˆ 5.4, 2.0, irrad. at 5.23 ! d, J ˆ 5.4, irrad. at 3.87 ! br. d, J ꢁ
2.0, H C(2)); 3.59 (dd, J ˆ 7.4, 6.1, Hexo C(6)); 3.87 (dq, J ꢁ 5.2, 1.6, irrad. at 5.23 ! dt, J ꢁ 5.2, 1.6, H C(3));
4.12 (dd, J ˆ 7.4, 1.1, Hendo C(6)); 4.61 (dq, J ꢁ 6.1, 1.5, irrad. at 3.87 ! dt, J ꢁ 6.1, 1.5, H C(5)); 4.67 (t, J ꢁ 1.8,
irrad. at 3.87 ! d, J ꢁ 2.0, H C(4)); 5.23 (br. s, irrad. at 3.87 ! d, J ˆ 2.0, H C(1)); 4.50 ± 5.50 (br. s, exchange
with D2O, HO C(2), HO C(3)). 13C-NMR (100 MHz, (D6)DMSO): 37.50 (q, MsO); 63.98 (t, C(6)); 65.72,
68.45 (2d, C(2), C(3)); 73.41 (d, C(4)); 79.56 (d, C(5)); 101.22 (d, C(1)). DCI-MS (MeOH): 258 (100, [M ‡
‡
‡
‡
NH4] ), 162 (95, [M Ms] ), 97 (94, [Ms ‡ NH4] ). Anal. calc. for C7H12O7S (240.23): C 35.00, H 5.03, S 13.35;
found: C 34.74, H 4.86, S 13.59.
1,6 :3,4-Dianhydro-b-d-taloyranose (6) [20][28]. 1m NaOMe in MeOH (500 ml) was added dropwise at 238
to a suspension of 5 (98.0 g, 408 mmol) and phenolphthalein (20 mg) in MeOH (2.0 l) at a rate to maintaining a
pink colour (addition of 200 ml led to a clear soln.). After the addition of further 1m NaOMe in MeOH (50 ml;
TLC: complete consumption of 5), stirring was continued for 2 h at 238. Solid NH4Cl was added, until the pink
colour vanished. After evaporation at 12 mbar and 238, the suspension of the residue in AcOEt, (500 ml) was
washed with H2O (80 ml, caution: the product is slightly H2O-soluble). Evaporation at 12 mbar and 238 and
crystallisation from AcOEt/pentane gave 6 (56.5g, 96%). White solid. Rf (AcOEt) 0.40. M.p. 73 ± 748 ([28]:
74.0 ± 75.28). IR and NMR, see [28].
1,6 :3,4-Dianhydro-2-O-(triisopropylsilyl)-b-d-talopyranose (7). At 238, a soln. of 6 (5.04 g, 3.5 mmol) in
pyridine (75 ml) and CH2Cl2 (50 ml) was treated with TIPSOTf (10.9 ml, 4.2 mmol), stirred for 20 min, treated
with H2O (250 ml), stirred for 1 h, and extracted three times with CH2Cl2. The combined org. layers were
washed with 2n H2SO4 and H2O, dried (MgSO4), and evaporated at 12 mbar and 408. FC (silica gel (200 g);
hexane/AcOEt 4 :1) of the residue (12 g) gave 7 (10.5 g, 99%). Colourless oil. Rf (hexane/AcOEt 4 :1) 0.36. Rf
(toluene/AcOEt 2 :3) 0.51. IR (neat): 2945s, 2867s, 1465m, 1148s, 1114m, 1082s, 980m, 924m, 882m, 839m, 813w,
747w. 1H-NMR (200 MHz, CDCl3): 1.10 ± 1.19 (m, (Me2CH)3Si); 3.25 (br. t, J ꢁ 3.9, irrad. at 3.96 ! change,
H
H
C(3)); 3.56 (dd, J ˆ 6.5, 5.0, irrad. at 4.75 ! d, J ˆ 6.5, Hexo C(6)); 3.68 (t, J ꢁ 4.4, irrad. at 4.75 ! d, J ˆ 4.5,
C(4)); 3.96 (t, J ꢁ 3.4, irrad. at 5.26 ! d, J ˆ 3.4, H C(2)); 4.07 (br. d, J ˆ 6.5, Hendo C(6)); 4.75 (br. t, J ꢁ
4.7, H C(5)); 5.26 (br. d, J ꢁ 3.4, irrad. at 3.96 ! s, H C(1)). 13C-NMR (50 MHz, CDCl3): 12.30 (d, (Me2CH)3-
Si); 17.95 (q, (Me2CH)3Si); 50.91 (d, C(3)); 55.95 (d, C(4)); 64.52 (t, C(6)); 68.97 (d, C(2)); 71.89 (d, C(5));
‡
‡
98.87 (d,C(1)). DCI-MS (MeOH): 318 (11, [M ‡ NH4] ), 301 (100, [M ‡ H] ), 257 (13), 227 (22), 211 (20).
Anal. calc. for C15H28O4Si (300.47): C 59.96, H 9.39; found: C 59.82, H 9.37.
1,6-Anhydro-4-deoxy-2-O-(triisopropylsilyl)-4-C-[2-(trimethylsilyl)ethynyl]-b-d-mannopyranose (8).
A
cooled (ice/NaCl) soln. of (trimethylsilyl)acetylene (TMSA, 2.08 ml, 15 mmol) in toluene (20 ml) was
successively treated with 1.6m BuLi in hexane (9.38 ml, 15 mmol), THF (1.0 ml), and 2.0m AlMe3 in heptane
(3.0 ml). The resulting colourless suspension was treated with a soln. of 5 (1.50 g, 5 mmol) in toluene (5.0 ml),
heated to 658, stirred for 75 min, cooled to 08, treated with sat. NH4Cl soln. (20 ml) and 2n HCl (50 ml), and
extracted with AcOEt. After drying (MgSO4) and evaporation at 14 mbar and 238, FC (200 g, hexane/AcOEt
5 :1 (600 ml) ! 10 :3 (400 ml)) of the yellow oily residue (2.3 g) gave 8 (1.69 g, 85%). Colourless oil. Rf (hexane/
AcOEt 4 :1) 0.40. [a]D27
ˆ
130.6 (c ˆ 1.0, MeOH). IR (neat): 3556w, 2956s, 2867s, 2178m, 1467m, 1250s, 1107s
(br.), 1028s, 877m, 850m, 761w. 1H-NMR (400 MHz, CDCl3): 0.15 (s, Me3Si); 1.05 ± 1.14 (m, (Me2CH)3Si); 3.00
(br. s, irrad. at 4.52 ! slimmer s, irrad. at 4.11 ! slimmer s, H C(4)); 3.25 (d, J ˆ 1.7, irrad. at 4.11 ! s, exchange
with CD3OD, HO C(3)); 3.71 (dd, J ˆ 7.0, 5.4, irrad. at 4.52 ! d, J ˆ 7.0, irrad. at 4.30 ! d, J ꢁ 5.4, Hexo C(6));
3.97 (dd, J ˆ 4.8, 1.6, irrad. at 4.11 ! d, J ꢁ 1.6, H C(2)); 4.11 (dquint., J ˆ 4.8, 1.6, irrad. at 4.52 ! dq, J ꢁ 4.8,
1.6, addn. of CD3OD ! dq, J ꢁ 4.8, 1.6, H C(3)); 4.30 (dd, J ˆ 6.9, 0.6, irrad. at 4.52 ! d, J ˆ 6.9, Hendo C(6));
4.52 (br. d, J ꢁ 4.9, irrad. at 4.11 ! slimmer d, J ꢁ 4.9, H C(5)); 5.34 (br. s, irrad. at 4.11 ! slimmer s, H C(1)).
13C-NMR (100 MHz, CDCl3): 0.04 (q, Me3Si); 12.19 (d, (Me2CH)3Si); 17.87 (q, (Me2CH)3Si); 38.87 (d, C(4));

Helvetica Chimica Acta ± Vol. 84 (2001)
2363
67.21 (t, C(6)); 68.43 (d, C(2)); 71.65 (d, C(3)); 74.59 (d, C(5)); 87.53 (s, CꢀCSi); 102.19 (d, C(1)); 104.31
‡
‡
(s, CꢀCSi). DCI-MS (MeOH): 416 (14, [M ‡ NH4] ), 400 (26), 399 (81, [M ‡ H] ), 381 (10), 357 (12), 356
(28), 355 (100, [M iPr] ), 337 (9), 309 (12), 225 (9), 173 (16), 73 (19, Me3Si ). Anal. calc. for C20H38O4Si2
‡
‡
(398.69): C 60.25, H 9.61; found: C 60.22, H 9.53.
1,6-Anhydro-4-deoxy-2,3-bis-O-(triisopropylsilyl)-4-C-[2-(trimethylsilyl)ethynyl]-b-d-mannopyranose (9).
A soln. of 8 (19.9 g, 50 mmol) in pyridine (125 ml) was treated with TIPSOTf (16.8 ml, 60 mmol), stirred at 808
for 24 h, cooled to 08, diluted with pentane/Et2O 5 :1 (600 ml), washed with 2n HCl (4 Â 50 ml) and brine
(50 ml), dried (MgSO4), and evaporated at 12 mbar and 238. FC (silica gel (500 g); pentane/Et2O 10 :1) gave 9
(24.9 g, 90%). Colourless oil. Rf (hexane/Et2O 10 :1) 0.41. IR (neat): 2945s, 2868s, 2176w, 1466m, 1390w, 1249m,
1152m, 1111w. 1H-NMR (400 MHz, CDCl3): 0.15 (s, Me3Si); 1.08 ± 1.14 (m, 2 (Me2CH)3Si); 2.83 (t, J ꢁ 1.6,
H
C(4)); 3.72 (dd, J ˆ 6.6, 5.6, Hexo C(6)); 4.01 (dd, J ˆ 4.2, 1.3, H C(2)); 4.33 (dq, J ꢁ 4.2, 1.5, H C(3));
4.40 (br. d, J ꢁ 6.8, Hendo C(6)); 4.47 (br. d, J ꢁ 5.2, H C(5)); 5.35 (br. s, H C(1)). 13C-NMR (100 MHz,
CDCl3): 0.00 (q, Me3Si); 12.86, 13.09 (2d, (Me2CH)3Si); 18.10, 18.26, 18.29, 18.34 (4q, 2 (Me2CH)3Si); 41.59
(d, C(4)); 67.28 (t, C(6)); 70.66 (d, C(2)); 74.45, 74.51 (2d, C(3), C(5)); 88.14 (s, CꢀCSi), 103.39 (d, C(1));
‡
104.67 (s, CꢀCSi). DCI-MS (MeOH): 555 (25, [M ‡ H] ), 511 (42), 381 (100), 272 (35), 337 (12), 304 (14), 287
‡
(23), 245 (12), 174 (24), 157 (19), 132 (17), 115 (13), 90 (10), 73 (21, Me3Si ).
2,6-Anhydro-3,7,8-trideoxy-4,5-bis-O-(triisopropylsilyl)-8-C-(trimethylsilyl)-3-C-[2-(trimethylsilyl)ethyn-
yl]-d-glycero-d-manno-oct-7-ynitol (10). A soln. of TMSA (24.5 ml, 180 mmol) in toluene (150 ml) was cooled
to 0 ± 28, treated with 2.5m BuLi in hexane (72.3 ml, 180 mmol), THF (10 ml), and AlCl3 (24.0 g, 180 mmol),
warmed to 238, and stirred for 45 min. The suspension was warmed to 658, treated with a soln. of 9 (10.0 g,
18 mmol) in toluene (30 ml), warmed to 808, stirred for 30 min, cooled to 238, and treated with sat. aq. NH4Cl
soln. (500 ml). After extraction with Et2O (4 Â 100 ml), the combined org. layers were dried (MgSO4) and
evaporated at 12 mbar and 248. FC (silica gel (200 g); hexane/Et2O 20 :1) gave pure 10 (8.43 g, 72%) and impure
fractions of 10. FC of these fractions (silica gel (100 g); hexane/Et2O 20 :1) gave further pure 10 (1.06 g, 9%).
Colourless oil. Rf (hexane/Et2O 10 :1) 0.32. IR (neat): 3603w, 3499w (br.), 2944s, 2893s, 2167m, 1461s, 1389m,
1333m, 1244s, 1161s, 1128s (br.), 1050s, 1016s, 883s, 844s (br.), 761s. 1H-NMR (400 MHz, CDCl3): 0.13, 0.18 (2s,
2 Me3Si); 1.06 ± 1.13 (m, 2 (Me2CH)3Si); 2.01 (br. s, exchange with D2O, HO C(1)); 3.05 (t, J ˆ 10.3, H C(3));
3.76 (br. dd, J ꢁ 10.4, 5.8, addn. of D2O ! dd, J ˆ 10.4, 5.8, Ha C(1)); 3.86 (ddd, J ˆ 10.3, 5.6, 2.7, H C(2)); 3.94
(br. d, J ꢁ 10.3, addn. of D2O ! dd, J ˆ 10.3, 2.7, Hb C(1)); 4.07 (t, J ˆ 2.3, irrad. at 4.61 ! d, J ˆ 2.3, H C(5));
4.41 (dd, J ˆ 10.3, 2.2, H C(4)); 4.61 (d, J ˆ 2.5, H C(6)). 13C-NMR (100 MHz, CDCl3): 0.31, 0.25
(2q, 2 Me3Si); 12.88, 13.14 (2d, 2 (Me2CH)3Si); 18.13, 18.20, 18.40, 18.46 (4q, 2 (Me2CH)3Si); 34.51 (d, C(3));
64.30 (t, C(1)); 70.60 (d, C(6)); 71.37 (d, C(4)); 73.18 (d, C(5)); 75.42 (d, C(2)); 89.02 (s, C(8)); 95.02
‡
(s, SiCꢀC C(3)); 100.00 (s, C(7)); 105.12 (s, SiCꢀC C(3)). DCI-MS (MeOH): 655 (15, [M ‡ H] ), 654 (25,
‡
‡
M ), 609 (26, [M iPr] ), 479 (100), 469 (17), 353 (16), 305 (49), 173 (9).
2,6-Anhydro-3,7,8-trideoxy-3-C-ethynyl-4,5-bis-O-(triisopropylsilyl)-d-glycero-d-manno-oct-7-ynitol (11).
A soln. of 10 (6.00 g, 9.18 mmol) in MeOH (100 ml) was treated with NaOMe (570 mg, 10.6 mmol), stirred
at reflux for 2 h, cooled to 08, and treated with NH4Cl (1.0 g). After evaporation at 10 mbar and 238, the
suspension of the residue in Et2O (250 ml) was washed with H2O (50 ml) and brine (2 Â 50 ml), followed by re-
extraction of the combined aq. layers with Et2O (2 Â 20 ml). The combined org. layers were dried (MgSO4), and
evaporated at 10 mbar and 358. Filtration over silica gel (50 g, hexane/Et2O 10 :1) gave 11 (4.57 g, 98%). White
solid. Rf (toluene/MeOH 10 :1) 0.56. M.p. 80 ± 818. IR (KBr): 3463m, 3309s, 3256s, 2944s, 2866s, 2112w, 1465s,
1386m, 1366m, 1244m, 1168s, 1128s, 1104m, 1071m, 1052m, 1032m, 1016m, 996m, 965m, 920w, 883s, 849s, 795m.
1H-NMR (500 MHz, CDCl3): 1.07 ± 1.12 (m, 2 (Me2CH)3Si); 1.93 (t, J ˆ 6.6, exchange with D2O, HO C(1));
2.09 (d, J ˆ 2.4, irrad. at. 3.05 ! s, HCꢀC C(3)); 2.62 (d, J ˆ 2.3, irrad. at 4.65 ! s, H C(8)); 3.05 (td, J ꢁ 10.3,
2.3, H C(3)); 3.79 (dt, J ꢁ 11.6, 5.9, addn. of D2O ! dd, J ˆ 11.6, 5.9, Ha C(1)); 3.89 (ddd, J ˆ 10.3, 5.8, 2.5,
irrad. at 3.05 ! dd, J ꢁ 5.8, 2.8, H C(2)); 3.95 (ddd, J ˆ 11.6, 6.6, 2.5, addn. of D2O ! dd, J ˆ 11.6, 2.5,
Hb C(1)); 4.10 (t, J ˆ 2.3, irrad. at 4.65 ! d, J ˆ 2.2, H C(5)); 4.41 (dd, J ˆ 10.3, 2.2, irrad. at 3.05 ! d, J ˆ 2.2,
H
C(4)); 4.65 (t, J ˆ 2.3, H C(6)). 13C-NMR (125 MHz, CDCl3, assignment based on a HSQC.GRASP
spectrum): 12.95, 13.20 (2d, 2 (Me2CH)3Si); 18.13, 18.19, 18.41, 18.43 (4q, 2 (Me2CH)3Si); 33.16 (d, C(3)); 63.99
(t, C(1)); 70.03 (d, C(6)); 71.36 (d, C(4)); 72.87 (s, HCꢀC C(3)); 73.02 (d, C(5)); 75.55 (d, C(2)); 77.74
‡
(s, C(8)); 78.62 (s, C(7)); 82.67 (s, HCꢀC C(3)). DCI-MS (MeOH): 510 (19), 509 (47, [M ‡ 1] ), 465 (89,
[M iPr] ), 411 (32), 397 (17), 335 (18), 291 (93), 267 (33), 261 (41), 249 (31), 173 (100), 161 (52), 157 (88),
‡
131 (89), 115 (77). Anal. calc. for C28H52O4Si2 (508.89): C 66.09, H 10.30; found: C 66.32, H 10.26.
2,6-Anhydro-3,7,8-trideoxy-3-C-ethynyl-d-glycero-d-manno-oct-7-ynitol (12). A soln. of 11 (800 mg,
1.6 mmol) in THF/H2O/CF3COOH 2 :1:1 (48 ml) was stirred for 25 h at 808. After evaporation at 12 mbar
and 408, the soln. of the residue in H2O (100 ml) was washed with pentane (3 Â 20 ml) and evaporated at

2364
Helvetica Chimica Acta ± Vol. 84 (2001)
12 mbar and 408. Two FC (silica gel (100 g); AcOEt/MeOH 10 :1; 20 g, AcOEt) gave 12 (347 mg, 92%).
Colourless foam. Rf (AcOEt/MeOH 10 :1) 0.18. Rf (AcOEt/MeOH 5 :1) 0.30. M.p. 101 ± 1028. IR (KBr): 3400s
(br.), 3291s, 2934m, 2116w, 1406m, 1339m, 1203m, 1136m, 1090s, 1025m, 989w, 957m, 841w, 789w. 1H-NMR
(500 MHz, CD3OD): 2.50 (d, J ˆ 2.4, irrad. at 2.73 ! s, HCꢀC C(3)); 2.73 (td, J ˆ 10.7, 2.3, irrad. at 3.97 !
dd, J ꢁ 10.5, 2.0, H C(3)); 3.12 (d, J ˆ 2.4, irrad. at 4.70 ! s, H C(8)); 3.74 (dd, J ˆ 11.9, 5.5, Ha C(1)); 3.81
(td, J ˆ 2.6, 0.4, irrad. at 4.70 ! br. d, J ˆ 2.5, H C(5)); 3.85 (ddd, J ˆ 10.7, 5.5, 2.2, irrad. at 2.73 ! dd, J ˆ 5.5,
2.2, H C(2)); 3.87 (dd, J ˆ 11.9, 2.2, Hb C(1)); 3.97 (dd, J ˆ 10.7, 3.0, irrad. at 2.73 ! d, J ˆ 3.0, H C(4)); 4.70
(t, J ꢁ 2.3, H C(6)). 13C-NMR (125 MHz, CD3OD, assignment based on a HSQC.GRASP spectrum): 33.90
(d, C(3)); 64.95 (t, C(1)); 70.69 (d, C(6)); 70.81 (d, C(4)); 71.61 (d, C(5)); 73.11 (s, HCꢀC C(3)); 76.49
‡
(d, C(2)); 79.07 (s, C(8)); 79.38 (s, C(7)); 82.95 (s, HCꢀC C(3)). DCI-MS (MeOH): 214 (100, [M ‡ NH4] ),
‡
197 (7, [M ‡ H] ), 165 (8), 147 (15), 124 (8), 119 (6). Anal. calc. for C10H12O4 (196.20): C 61.22, H 6.16; found:
C 61.19, H 6.12.
1,6-Anhydro-2,3,4-tris-O-(triisopropylsilyl)-b-d-mannopyranose (14). A soln. of 13 (648 mg, 4.0 mmol) in
pyridine/(Cl2CH)2 1:1 (10.0 ml) was treated with TIPSOTf (4.43 ml, 16 mmol), stirred at 1108 for 15 h, cooled
to 238, and treated with H2O (100 ml). After extraction with Et2O (4 Â 50 ml), the combined org. layers were
washed with 2n HCl (20 ml), dried (MgSO4), and evaporated at 12 mbar and 708. FC (silica gel (60 g); hexane/
Et2O 10 :1) gave 14 (2.32 g, 92%). Colourless oil. Rf (hexane/Et2O 10 :1) 0.45. IR (neat): 2944s, 2867s, 1464m,
1384w, 1367w, 1347w, 1248w, 1192w, 1154m, 1111s, 1064m, 1014m, 995m, 937m, 882s, 824m, 770w, 746m.
1H-NMR (400 MHz, CDCl3): 1.08 ± 1.11 (m, 3 (Me2CH)3Si); 3.65 (t, J ꢁ 6.2, Hexo C(6)); 3.93 (dd, J ˆ 4.2, 2.2,
irrad. at 5.34 ! d, J ˆ 4.2, irrad. at 4.14 ! br. s, H C(2)); 3.97 (t, J ꢁ 2.2, irrad. at 4.14 ! d, J ˆ 2.0, H C(4));
4.14 (dq, J ꢁ 4.1, 1.7, irrad. at 5.34 ! dt, J ˆ 4.0, 1.7, H C(3)); 4.35 (br. dt, J ꢁ 6.0, 2.0, irrad. at 4.14 ! br. dd, J ꢁ
6.0, 2.0, H C(5)); 4.36 (dd, J ˆ 6.5, 0.6, Hendo C(6)); 5.34 (t, J ꢁ 1.5, irrad. at 4.14 ! br. s, H C(1)). 13C-NMR
(100 MHz, CDCl3): 12.47, 12.85, 13.10 (3d, 3 (Me2CH)3Si); 17.99, 18.07, 18.21, 18.32, 18.41 (5q, 3 (Me2CH)3Si);
64.66 (t, C(6)); 70.25, 74.38, 75.45, 76.32 (4d, C(2), C(3), C(4), C(5)); 103.15 (d, C(1)). DCI-MS (MeOH)): 648
‡
‡
(1, [M ‡ NH4] ), 631 (2, [M ‡ 1] ), 587 (45), 541 (10), 457 (100), 413 (29), 411 (14), 385 (29), 372 (32), 304
(10), 287 (26), 185 (12), 157 (15), 115 (10). Anal. calc. for C33H70O5Si3 (631.17): C 62.80, H 11.18; found:
C 62.71, H 11.02.
2,6-Anhydro-3,4,5-tris-O-(triisopropylsilyl)-8-C-(trimethylsilyl)-d-glycero-d-manno-oct-7-ynitol (15).
Treatment of 14 (631 mg, 1.0 mmol), similarly as described for the conversion of 9 to 10, gave 15 (609 mg,
83%) after workup and FC (silica gel (140 g); hexane/AcOEt 10 :1). Colourless oil. Rf (hexane/Et2O 10 :1) 0.35.
IR (neat): 3467w, 2946s, 2871s, 2173w, 1463m, 1391m, 1367m, 1250s, 1103s (br.), 1068s, 1034s, 999s, 947m, 919m,
884s, 856s, 843s, 781m, 761s. 13C-NMR (100 MHz, CDCl3): 0.30 (q, Me3Si); 13.21 (d, 3 (Me2CH)3Si); 18.07,
18.13, 18.38, 18.41 (4q, 3 (Me2CH)3Si); 61.85 (t, C(1)); 64.44 (d, C(3)); 68.17 (d, C(6)); 72.70 (d, C(4)); 75.69
‡
(d, C(5)); 79.79 (d, C(2)); 90.77 (s, C(8)); 104.44 (s, C(7)). ESI-MS: 752 (22), 751 (36, [M ‡ Na] ), 747 (34),
‡
‡
746 (56, [M ‡ NH4] ), 731 (35), 730 (63), 729 (100, [M ‡ 1] ).
2,6-Anhydro-d-glycero-d-manno-oct-7-ynitol (16). A soln. of 15 (360 mg, 0.49 mmol) in THF/CF3COOH/
H2O 2 :1:1 (40 ml) was kept at reflux for 67 h and evaporated at 12 mbar and 508. A soln. of the residue in H2O
(50 ml) was washed with AcOEt (3 Â 5 ml) and evaporated. FC (silica gel (20 g); AcOEt/MeOH/H2O 17:3 :2)
gave a white solid (96 mg), which was dissolved in 0.01m NaOMe in MeOH (20 ml) and stirred at 238 for 1.5 h.
After the addition of phenolphthalein (2 mg), the pink soln. was treated portionwise with NH4Cl until
disappearance of the colour. Evaporation at 12 mbar and 238 and FC (silica gel (20 g); AcOEt/MeOH/H2O
17:3 :2) gave 14 (70 mg, 76%). White solid. Rf (AcOEt/MeOH/H2O 17:3 :2) 0.41. M.p. 73 ± 748. IR (neat):
3371s (br.), 3302s, 2116w, 1437m, 1335m, 1205s, 1143s, 1091s, 1026s, 959w, 916w, 842w, 802m. 1H-NMR
(500 MHz, CD3OD): 3.09 (d, J ˆ 2.4, irrad. at 4.65 ! s, H C(8)); 3.60 (t, J ˆ 9.4, H C(3)); 3.69 ± 3.74
(m, Ha C(1), H C(2)); 3.81 ± 3.85 (m, Hb C(1)); 3.85 (dd, J ˆ 9.4, 3.3, H C(4)); 3.91 (dd, J ˆ 3.3, 2.1, irrad.
at 4.65 ! d, J ˆ 3.3, H C(5)); 4.65 (t, J ˆ 2.2, H C(6)). 13C-NMR (125 MHz, CD3OD, assignment based on a
HSQC.GRASP spectrum): 62.86 (t, C(1)); 68.60 (d, C(3)); 70.49 (d, C(6)); 72.88 (d, C(4)); 73.94 (d, C(5));
‡
77.42 (d, C(2)); 78.70 (s, C(8)); 79.67 (s, C(7)). HR-ESI-MS (positive mode): 206.1031 (C8H16NO5, [M ‡ NH4] ;
calc. 206.1028).
1,1'-(Buta-1,3-diyne-1,4-diyl)bis[(1R)-1,5-anhydro-4-deoxy-4-C-ethynyl-2,3-bis-O-(triisopropylsilyl)-d-
mannitol] (17). A soln. of 11 (200 mg, 0.39 mmol) in pyridine (5 ml) was treated with Cu(OAc)2 (713 mg,
3.9 mmol), stirred at 238 for 6 d, concentrated to 1 ml at 10 mbar and 238, and diluted with H2O (30 ml). After
extraction with Et2O (4 Â 30 ml), the combined org. layers were washed with brine, dried (MgSO4), and
evaporated at 10 mbar and 238. FC (silica gel (20 g); hexane/AcOEt 5 :1) followed by FC (silica gel (100 g);
pentane/toluene/AcOEt 5 :5 :1) gave 17 (153 mg, 77%). White solid. Rf (toluene/MeOH 10 :1) 0.45. M.p. 116 ±
1188. IR (KBr): 3472m, 3315m, 2944s, 2892s, 2867s, 1465m, 1386w, 1367w, 1249w, 1162s, 1129s, 887m, 884m,

Helvetica Chimica Acta ± Vol. 84 (2001)
2365
857m, 799w. Raman (neat): 2943m, 2890m, 2865m, 2248s, 2120w, 1470w, 1241w, 883w. 1H-NMR (500 MHz,
CDCl3): 1.08 ± 1.13 (m, 2 (Me2CH)3Si); 1.8 ± 2.1 (br. s, HO C(6)); 2.11 (d, J ˆ 2.4, HCꢀC C(4)); 3.07
(br. td, J ꢁ 10.2, 2.2, H C(4)); 3.80 (dd, J ˆ 11.3, 5.5, Ha C(6)); 3.87 (ddd, J ˆ 10.3, 5.5, 2.2, H C(5)); 3.98
(dd, J ꢁ 11.3, 1.9, Hb C(6)); 4.11 (br. t, J ꢁ 2.2, H C(2)); 4.33 (dd, J ˆ 10.3, 2.1, H C(3)); 4.72 (d, J ˆ 2.2,
H
C(1)). 13C-NMR (125 MHz, CDCl3, assignment based on a HSQC.GRASP spectrum): 12.87, 13.45
(2d, 2 (Me2CH)3Si); 18.07, 18.13, 18.37, 18.40 (4q, 2 (Me2CH)3Si); 33.04 (d, C(4)); 63.85 (t, C(6)); 70.52
(d, C(1)); 71.68 (d, C(3)); 72.82 (s, CꢀC C(1)); 73.08 (s, HCꢀC C(4)); 73.01 (d, C(2)); 75.29
(s, CꢀC C(1)); 76.09 (d, C(5)); 82.37 (s, HCꢀC C(4)). ESI-MS (MeOH/AcOH): 1039 (85), 1038 (100,
‡
‡
[M ‡ Na] ), 1016 (44, [M ‡ H] ).
1,1':4,4'-Bis(buta-1,3-diyne-1,4-diyl)bis[(1R)-1,5-anhydro-4-deoxy-2,3-bis-O-(triisopropylsilyl)-d-manni-
tol] (18). a) From 17: A soln. of 17 (1.02 g, 1.0 mmol) in pyridine (1.0 l) was treated with Cu(OAc)2 (564 mg,
3.0 mmol), stirred at 1008 for 7 h, and evaporated at 30 mbar and 408. A suspension of the residue in pentane
(250 ml) was washed with 2n HCl (2 Â 20 ml), 25% aq. NH3 soln. (20 ml), and brine (3 Â 20 ml), dried
(MgSO4), and evaporated at 12 mbar and 238. Filtration through a pad of silica gel (5 Â 1 cm, pentane) and FC
(pentane/AcOEt 20 :3) gave 18 (722 mg, 71%).
b) From 11: A soln. of 11 (509 mg, 1 mmol) in pyridine (50 ml) was treated with Cu(OAc)2 (377 mg,
2 mmol), stirred at 238 for 3 d, and transferred via a cannula into a soln. of Cu(OAc)2 (377 mg, 2 mmol) in
pyridine (500 ml). The mixture was stirred at 1008 for 7 h and concentrated to 5 ml at 408 and 30 mbar. The
suspension of the residue in pentane (250 ml) was washed with 2n HCl (3 Â 20 ml), 25% aq. NH3 soln. (20 ml),
and brine (2 Â 20 ml), dried (MgSO4), and evaporated. FC (silica gel (100 g); pentane/AcOEt 20 :3) of the
residue (408 mg) gave 18 (329 mg, 65%). White solid. Rf (cyclohexane/AcOEt 10 :1) 0.43. M.p. >1808
(decomp.). IR (KBr): 3484w (br.), 3311w, 2945s, 2890m, 2868s, 1464m, 1390w, 1243w, 1164s, 1116s, 1099s,
1015m, 883s. Raman (neat): 2946s, 2890m, 2865s, 2230s, 1470w, 1240w, 881w. 1H-NMR (500 MHz, CDCl3): 1.04 ±
1.11 (m, 2 (Me2CH)3Si); 2.12 (br. s, HO C(6)); 2.63 (t, J ꢁ 7.7, H C(4)); 3.67 (dd, J ˆ 11.7, 4.8, Ha C(6)); 3.81
(dd, J ˆ 11.6, 2.7, Hb C(6)); 4.16 (ddd, J ˆ 7.8, 4.2, 2.7, H C(5)); 4.22 (t, J ꢁ 3.2, H C(2)); 4.54 (dd, J ˆ 7.5, 3.0,
H
C(3)); 4.58 (d, J ˆ 3.4, H C(1)). 13C-NMR (125 MHz, CDCl3): 12.89, 13.21 (2d, 2 (Me2CH)3Si); 18.13,
18.19, 18.34, 18.38 (4q, 2 (Me2CH)3Si); 36.38 (d, C(4)); 64.15 (t, C(6)); 70.64 (s, CꢀC); 70.70 (d, C(1)); 72.61
(d, C(3)); 74.05 (d, C(2)); 75.18 (s, CꢀC); 77.34 (d, C(5)); 78.47 (s, CꢀC); 92.81 (br. s, CꢀC). MALDI-TOF-
‡
MS: 1036 ([M ‡ Na] ). Anal. calc. for C56H100O8Si4 (1013.74): C 66.35, H 9.94; found: C 66.35, H 9.77.
1,1':4,4'-Bis(buta-1,3-diyne-1,4-diyl)bis[(1R)-1,5-anhydro-4-deoxy-6-O-(methylsulfonyl)-2,3-bis-O-(triiso-
propylsilyl)-d-mannitol] (19). A soln. of 18 (101 mg, 0.10 mmol), pyridine (200 ml, 2.48 mmol), and MsCl (80 ml,
1 mmol) in CH2Cl2 (5.0 ml) was stirred at 238 for 16 h, treated with H2O (5 ml), and stirred for 2 h. After
extraction with CH2Cl2 (2 Â 20 ml), the combined org. layers were washed with brine, filtered through cotton,
and evaporated. FC (silica gel (10 g); heptane/AcOEt 10 :3) gave 19 (108 mg, 99%). White solid, decomposing
at 238 within several days. Rf (heptane/AcOEt 10 :3) 0.24. IR (KBr): 2944s, 2866s, 1732w, 1464s, 1352s, 1243m,
1
1185s, 1134s, 1090s, 1009s, 984s, 883s, 848s, 796m. H-NMR (400 MHz, CDCl3): 1.09 ± 1.12 (m, 2 (Me2CH)3Si);
2.49 (t, J ꢁ 7.2, H C(4)); 3.02 (s, MsO); 4.27 (br. t, J ꢁ 3.0, H C(2)); 4.27 ± 4.36 (m, H C(5), Ha C(6)); 4.37
(dd, J ˆ 9.7, 6.1, Hb C(6)); 4.53 (dd, J ˆ 7.1, 3.0, H C(3)); 4.60 (d, J ˆ 3.3, H C(1)). 13C-NMR (100 MHz,
CDCl3): 12.92, 13.13 (2d, 2 (Me2CH)3Si); 18.11, 18.19, 18.32, 18.27 (4q, 2 (Me2CH)3Si); 36.47 (d, C(4)); 37.63
(q, MsO); 69.87 (t, C(6)); 70.88 (d, C(1)); 70.91 (s, CꢀC); 72.52 (d, C(3)); 73.79 (d, C(2)); 74.64 (d, C(5)); 75.32
(s, CꢀC); 78.48 (s, CꢀC); 90.96 (br. s, CꢀC).
X-Ray Analysis of 19. Crystallisation of 19 from pentane by slow evaporation of the solvent at ambient
temp. for 18 h gave crystals suitable for X-ray analysis. C58H104O12S2Si4 (1169.89); monoclinic, P2(1) no. 4; a ˆ
19.782(2) Š, b ˆ 8.406(2) Š, c ˆ 21.157(5) Š, b ˆ 106.42(1)8; Vˆ 3374.7(12) Š3; Dx ˆ 1.151 Mg/m3; Z ˆ 2.
Intensities were measured in the w-scan mode on an Enraf-Nonius CAD-4 diffractometer with CuKa radiation
(l ˆ 1.54180 Š) at 170 K, V range 2.18 ± 59.948. Of the 5541 total collected reflections, 5223 independent
reflections were observed. R ˆ 0.0301, Rw ˆ 0.0804. The structure was solved with the direct-methods routine of
SHELXS-86, and the refinement was performed with SHELXL-93 [29].
1,1':4,4'-Bis(butane-1,4-diyl)bis[(1R)-1,5-anhydro-4-deoxy-2,3-bis-O-(triisopropylsilyl)-d-mannitol] (20).
A suspension of 18 (40 mg, 0.0395 mmol) and 10% Pd on charcoal (40 mg) in AcOH (2.0 ml) was hydrogenated
(6 bar of H2) at 238 for 16 h and filtered through Celite (2 g, Et2O). Evaporation and filtration through silica gel
(1.5 g, cyclohexane/Et2O 30 :1) gave 20 (32 mg, 79%). White solid. Rf (cyclohexane/Et2O 20 :1) 0.43. M.p. 218 ±
2208. IR (KBr): 3544s, 3478s, 3416s, 2946s, 2867s, 1466m, 1385w, 1239w, 1163m, 1136m, 1106m, 1083m, 1087m,
1029m, 932w, 883m, 842m. 1H-NMR (400 MHz, CDCl3): 1.07 ± 1.11 (m, 2 (Me2CH)3Si); 1.18 ± 1.26 (m, 2 H);
1.34 ± 1.46 (m, 3 H); 1.50 ± 1.65 (m, 2 H); 2.05 ± 2.23 (m, 3 H, 1 H exchanged with D2O); 3.61 (dt, J ꢁ 10.8, 5.4,
addn. of D2O ! dd, J ꢁ 11.5, 6.6, Ha C(6)); 3.74 ± 3.79 (m, addn. of D2O ! change, H C(1), H C(5),

2366
Helvetica Chimica Acta ± Vol. 84 (2001)
Hb C(6)); 3.93 (t, J ˆ 2.1, H C(2)); 4.07 (dd, J ˆ 10.5, 2.4, H C(3)). 13C-NMR (100 MHz, CDCl3): 13.49,
13.52 (2d, 2 (Me2CH)3)Si); 18.33, 18.38, 18.40, 18.52 (4q, 2 (Me2CH)3Si); 24.21, 24.25, 27.17, 28.25
(4t, 2 CH2CH2); 38.29 (d, C(4)); 64.10 (t, C(6)); 68.04 (d, C(1)); 71.38 (d, C(3)); 74.24 (d, C(2)); 78.31
‡
(d, C(5)). MALDI-TOF-MS: 1051 ([M ‡ Na] ). Anal. calc. for C56H116O8Si4 (1029.87): C 65.31, H 11.35; found:
C 65.36, H 11.10.
1,1':4,4'-Bis(butane-1,4-diyl)bis[(1R)-1,5-anhydro-4-deoxy-d-mannitol] (21).
A soln. of 20 (50 mg,
485 mmol) in THF (5 ml) was treated with TBAF on silica gel (440 mg, 1.1 mmol F /g, 0.485 mmol), stirred
at 238 for 15 h and at 408 for 3 h, treated with MeOH (5.0 ml), and stirred for 20 min. After filtration and
washing the solid with MeOH (30 ml), evaporation of the combined filtrate, and washings at 12 mbar and 308
gave a yellow oil (250 mg). FC (silica gel (6 g); AcOEt/MeOH/H2O 15 :3 :1) followed by FC (silica gel (5 g);
CH2Cl2/MeOH 10 :3) gave 21 (19 mg, 97%). White solid. Rf (AcOEt/MeOH/H2O 15 :3 :2) 0.23. Rf (CH2Cl2/
MeOH 10 :3) 0.16. IR (KBr): 3419s (br.), 2948s, 2867m, 1638m, 1616m, 1461w, 1411w, 1383w, 1344w, 1261w,
1
1185w, 1129m, 1068m, 979w, 918w, 868w, 801w, 734m. H-NMR (300 MHz, CD3OD, 558): 1.20 ± 1.40 (m, 3 H),
1.40 ± 1.90 (m, 6 H) (2 CH2CH2, H C(4)); 3.63 (dd, J ˆ 11.7, 2.8, Ha C(6)); 3.645 (dd, J ˆ 5.5, 3.4, H C(2));
1
3.75 (td, J ˆ 6.5, 2.8, H C(5)); 3.79 ± 3.86 (m, H C(1), H C(3)); 3.92 (dd, J ˆ 11.7, 6.7, Hb C(6)). H-NMR
(400 MHz, CD3OD, 238): 1.20 ± 1.40 (m, 3 H), 1.40 ± 1.90 (m, 6 H) (2 CH2CH2, H C(4)); 3.61 (br. d, J ꢁ 12.0,
Ha C(6)); 3.645 (dd, J ˆ 5.5, 3.4, H C(2)); 3.75 (td, J ˆ 6.5, 2.8, H C(5)); 3.80 ± 3.85 (m, H C(1), H C(3));
3.90 ± 4.05 (br. s, Hb C(6)). 1H-NMR (400 MHz, CD3OD, 808): 1.18 ± 1.38 (m, 5 H), 1.38 ± 2.05 (m, 4 H)
(2 CH2CH2, H C(4)); 3.21 (br. d, J ꢁ 12.0, Ha C(6)); 3.30 (br. s, H C(2)); 3.48 ± 3.90 (m, H C(1), H C(3),
H
C(5)), Hb C(6)). 13C-NMR (75 MHz, CD3OD, 238): 24.93, 26.96, 27.24, 30.46 (4t, 2 CH2CH2); 40.60
(br. d, C(4)); 64.13 (t, C(6)); 69.57 (br. d, C(1), C(3)); 74.03 (d, C(2)); 74.5 (br. d, C(5)). 13C-NMR (75 MHz,
CD3OD, 558): 25.01, 27.04, 27.38, 30.55 (4t, 2 CH2CH2); 40.71 (d, C(4)); 64.44 (t, C(6)); 69.91 (br. d, C(1), C(3));
‡
74.18 (d, C(2)); 74.96 (br. d, C(5)). ESI-MS: 427 (51, [M ‡ Na] ), 242 (100).
X-Ray Analysis of 21 ´ MeOH. Crystallisation of 21 from MeOH by slow evaporation of the solvent at
ambient temp. gave crystals of 21 ´ MeOH suitable for X-ray analysis. M.p. 212 ± 2138. C20H36O8 ´ CH4O (436.53);
orthorhombic, P2(1)2(1)2(1); a ˆ 8.472(2), b ˆ 14.498(3), c ˆ 18.271(6) Š; Vˆ 2244.2(10) Š3; Dx ˆ 1.292 Mg/
m3; Z ˆ 4. Intensities were measured in the w-scan mode on an Enraf-Nonius CAD-4 diffractometer with CuKa
radiation (l ˆ 1.54180 Š) at 223 K, V range 3.89 ± 64.888. Of the 2230 total collected reflections, 2184
independent reflections were observed. R ˆ 0.0304, Rw ˆ 0.0787. The structure was solved by direct methods
(SIR92 [30]), and refined by full-matrix least-squares analysis (SHELXL97 [29]), using an isotropic extinction
correction (heavy atoms anisotropic, H-atoms isotropic). Most H-positions of CH groups are based on
stereochemical considerations, those of OH groups were located from an electron-density difference-map and
refined without restraints.
REFERENCES
[1] B. Hoffmann, D. Zanini, I. Ripoche, R. Bürli, A. Vasella, Helv. Chim. Acta 2001, 84, 1862.
[2] T. V. Bohner, O.-S. Becker, A. Vasella, Helv. Chim. Acta 1999, 82, 198.
[3] J. Alzeer, C. Cai, A. Vasella, Helv. Chim. Acta 1995, 78, 242.
[4] J. Alzeer, A. Vasella, Helv. Chim. Acta 1995, 78, 177.
[5] R. Bürli, A. Vasella, Helv. Chim. Acta 1996, 79, 1159.
[6] R. Bürli, A. Vasella, Helv. Chim. Acta 1997, 80, 2215.
[7] T. Lowary, M. Meldal, A. Helmboldt, A. Vasella, K. Bock, J. Org. Chem. 1998, 63, 9657.
[8] T. Nishikawa, M. Ishikawa, M. Isobe, Synlett 1999, 123.
[9] A. Dondoni, G. Mariotti, A. Marra, Tetrahedron Lett. 2000, 41, 3483.
[10] T. M. Davis, T. L. Lowary, Carbohydr. Res. 2000, 324, 210.
[11] R. M. Hann, C. S. Hudson, J. Am. Chem. Soc. 1942, 64, 925.
[12] M. A. Zottola, R. Alonso, G. D. Vite, B. Fraser-Reid, J. Org. Chem. 1989, 54, 6123.
[13] J. Stanek, M. Cerny, Synthesis 1972, 698.
[14] S. Ogawa, Y. Nakamura, Carbohydr. Res. 1992, 226, 79.
[15] C. Li, B. Bernet, A. Vasella, E. A. Broger, A. Meili, Carbohydr. Res. 1991, 216, 149.
[16] T. D. Nelson, R. D. Crouch, Synthesis 1996, 1031.
[17] C. Rücker, Chem. Rev. 1995, 95, 1009.
[18] R. J. Batten, A. J. Dixon, R. J. K. Taylor, Synthesis 1980, 234.
[19] R. Gleiter, R. Merger, in ꢀModern Acetylene Chemistryꢁ, Eds. F. Diederich and P. J. Stang, VCH,
Weinheim, 1995, p. 285.

Helvetica Chimica Acta ± Vol. 84 (2001)
2367
[20] M. Meier, Adv. Strain Org. Chem. 1991, 1, 215.
[21] S. K. Collins, G. P. A. Yap, A. G. Fallis, Angew. Chem., Int. Ed. 2000, 39, 385.
[22] K. N. Houk, L. T. Scott, N. G. Rondan, D. C. Spellmeyer, G. Reinhardt, J. L. Hyun, G. J. Decicco, R. Weiss,
M. H. M. Chen, L. S. Bass, J. Clardy, F. S. Jùrgensen, T. A. Eaton, V. Sarkozi, C. M. Petit, L. Ng, K. D.
Jordan, J. Am. Chem. Soc. 1985, 107, 6556.
[23] R. Gleiter, R. Merger, J. Chavez, T. Oeser, H. Irngartinger, H. Pritzkow, B. Nuber, Eur. J. Org. Chem. 1999,
2841.
[24] U. H. F. Bunz, V. Enkelmann, Chem.±Eur. J. 1999, 5, 263.
[25] A. G. Meister, R. F. Cleveland, J. Chem. Phys. 1944, 12, 313; I. Moggio, M. Alloisio, A. Cravino, D.
Comoretto, P. Piaggio, G. F. Musso, G. Garbarino, C. Cuniberti, C. DellꢁErba, G. Dellepiane, J. Chem. Soc.,
Perkin Trans. 2 1998, 2249.
[26] L. T. Scott, G. J. DeCicco, J. L. Hyun, G. Reinhardt, J. Am. Chem. Soc. 1985, 107, 6546.
[27] T. D. W. Claridge, ꢀHigh-Resolution NMR Techniques in Organic Chemistryꢁ, in ꢀTetrahedron Organic
Chemistry Seriesꢁ, Eds. J. E. Baldwin, F. R. S. Williams, and M. Williams, Pergamon, Amsterdam, 1999,
Vol. 19, p. 142.
[28] K. Matsumoto, T. Ebata, K. Koseki, K. Okano, H. Kawakami, H. Matsuhita, Carbohydr. Res. 1993, 246,
345.
[29] G. M. Sheldrick, ꢀSHELXS-86, SHELXL-93, and SHELXL97: Programs for the Refinement of Crystal
Structuresꢁ, University of Göttingen, Germany.
[30] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M. C. Burla, G. Polidori, M. Camalli, J. Appl.
Crystallogr. 1994, 27, 435.
Received July 6, 2001