Studies on the synthesis of trisaccharide analogues of the antibiotic moenomycin A

Article abstract of DOI:10.1002/hlca.200490160

A new approach for the synthesis of moenomycin trisaccharide analogues is reported in which three monosaccharide building blocks are used and allows the introduction of different substituents at the 6-position of unit E (Scheme 2). Furthermore, a new proc

Full text of DOI:10.1002/hlca.200490160

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Helvetica Chimica Acta Vol. 87 (2004)
Studies on the Synthesis of Trisaccharide Analogues of the Antibiotic
Moenomycin A
by Guangbin Yang, Lothar Hennig, Matthias Findeisen, Ramona Oehme, Sabine Giesa, and Peter Welzel*
Universit‰t Leipzig, Fakult‰t f¸r Chemie und Mineralogie, Johannisallee 29, D-04103 Leipzig
(fax: ‡‡ 49341 9736599; e-mail: welzel@chemie.uni-leipzig.de)
A new approach for the synthesis of moenomycin trisaccharide analogues is reported in which three
monosaccharide building blocks are used and allows the introduction of different substituents at the 6-position
of unit E (Scheme 2). Furthermore, a new procedure for the introduction and manipulation of unit F is described
(Scheme 3).
Introduction. The moenomycins are a group of compounds that inhibit highly
efficiently the transglycosylation step, i.e., the formation of the sugar strands, in the
biosynthesis of the bacterial cell wall peptidoglycan component. There is experimental
evidence that the transglycosylation proceeds in such a way that the growing
polysaccharide chain is the glycosyl donor, whereas the disaccharide derivative lipid
II is the glycosyl acceptor (for a review, see [1]). A representation of the transition state
is displayed in the Figure.
Fig. 1. Putative mechanism of the transglycosylation reaction
The transglycosylation is catalyzed by a number of multimodular bifunctional
polymerases (that also catalyze the crosslinking transpeptidation reaction) designated

Helvetica Chimica Acta Vol. 87 (2004)
1795
as class-A high-molecular-mass penicillin-binding proteins (PBPs). One of them, viz.
PBP 1b from E. coli, has been studied in great detail [2]. Moenomycin A (1) binds
reversibly to E. coli PBP 1b [1]. From structure-activity relationships [3][4], it has been
inferred that the moenomycins, after unselective anchoring to the cytoplasmic
membrane via their lipid moiety (for a discussion, see [5]), bind highly selectively
via their carbohydrate part to the donor binding subsites of the enzyme. The structural
features that are known to be responsible for the antibiotic activity are indicated by full
arrows in 2 [3][4]. It is assumed that units C and E of 1 and 2, respectively, compete
with the second and the third sugar unit of the growing peptidoglycan chain for the
binding subsites at the enzyme. The different binding of the first two sugar units (1 ! 4
in the growing peptidoglycan strand (see Figure) vs. 1 ! 2 in 1 and 2, resp.) as indicated
by curved arrows has been suggested to be responsible for the inhibition of the enzyme
[6]. The conclusions from structure-activity-relationship (SAR) studies are corrobo-
rated by NMR results, especially from STD NMR experiments [7][8] from which it has
been inferred that the N-acetyl groups of units C and E are in contact with the enzyme
in the ligand/protein complex [9]. A recent publication by Kahne and co-workers [10]
requires comment. They found that the inhibition of PBP 1b by moenomycin cannot be
overcome by lipid-II and argued that this result disproves the prediction that
moenomycin is a competitive inhibitor with respect to lipid II. The position that
Kahne and co-workers take in their paper ignores completely the SAR results that have
accumulated and which have led to the mechanistic picture outlined above [3][4].
Furthermore, an IC50 of ca. 2 ¥ 10À9 mol lÀ1 has been determined for moenomycin (using
cell-wall-membrane material isolated from E. coli) [11]. Most probably, moenomycin
is a tight-binding inhibitor [12]. It is, therefore, not at all unreasonable to assume
that lipid II, with an affinity for the acceptor site of only ca. 2 3 mm, does not over-
come binding of moenomycin at the donor site (which is not the lipid II binding site,
with the possible exception of the initiating step of the sugar-chain formation). Even
the observation that lipid II does not compete with an analogue of moenomycin lacking
a large part of the lipid moiety does, in our opinion, not support the conclusions of
Kahne and co-workers. Indeed, the binding of this compound, which in vivo is
antibiotically inactive, to PBP 1b is strong enough to permit affinity purification of the
enzyme [13]1).
The moenomycin analogues employed for the SAR and mode-of-action studies
have been obtained i) by selective degradation of 1 [14], ii) by attachment of reporter
groups to unit A of 1 [15], and iii) by synthesis of moenomycin A trisaccharide
analogues [6][16][17]. The latter approach is the most demanding but, of course, also
the most promising one, since approaches i) and ii) allow the preparation of analogues
with only limited diversity. Furthermore, reporter groups attached to unit A of 1 are
rather far away from that part of the antibiotic which is in contact with the enzyme.
Thus, it seems worthwhile to develop synthetic routes towards moenomycin analogues
containing at least three sugar units (C E F, see formula 1)2). Sofia and co-workers
reported on the library synthesis of disaccharide analogues, but the substances
1
)
)
See also the NMR results [9].
The different building blocks of the compounds discussed in this paper are indexed exactly as in
2
moenomycin (1).

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Helvetica Chimica Acta Vol. 87 (2004)
accessible by their route do not meet the structural requirements for a moenomycin-
type mode of action [18]. We devised a strategy that is characterized by coupling an
oligosaccharide 3 via a phosphoric acid diester linker to the 3-OH group of a 2-O-
alkylated glyceric acid building block 4, making use of a bis-electrophilic phosphoric
acid equivalent 5 (Scheme 1; X ˆ leaving group, Yˆ electron pair). Recently, the
problems associated with the synthesis of 2-O-substituted glycerates 4 were solved
adequately [19]. All previously reported syntheses of moenomycin trisaccharide
analogues used a C E disaccharide building block (chitobiose [16], cellobial [6],
lactosamine [17]). Here and in the accompanying publication, we wish to describe a
new approach that commences from three monosaccharide building blocks and is
flexible in such a way that it allows the introduction of different substituents at C(6) of
unit E, the substitution of which is unimportant as far as the antibiotic properties are
concerned (see dotted arrows in 2) [3]. It is anticipated that this position can be used to
attach reporter groups much closer to the moenomycin binding site at the enzyme.
Furthermore, we describe a new procedure for the introduction and manipulation of
unit F 3).
Synthesis of Trisaccharide 10a with the Phthaloyl (Phth) Protecting Group in Units
C and E and a Phenyl Carbonate as a Latent Carbamoyl Group in Unit F. The N-
phthaloyl-protected glucosamine derivative 6a [21] with a free 1-OH group and the
corresponding trichloroacetimidate 6b were synthesized by published methods [22]
(Scheme 2). Silylation of the anomeric OH group of 6a with (tert-butyl)dimethylsilyl
chloride and 1H-imidazole in DMF [23] gave silyl derivative 6c in high yield. Removal
«
of all acetyl groups of 6c under Zemplen conditions (6c ! 6d) and subsequent selective
silylation of the 6-OH group with (tert-butyl)diphenylsilyl chloride and 1H-imidazole in
DMF afforded compound 6e, the acetyl derivative 6f, which was prepared to facilitate
1H-NMR analysis. Me3SiOTf-Promoted coupling of trichloroacetimidate 6b with
acceptor 6e that has free OH groups in the 3- and the 4-position in CH2Cl2 solution gave
3
)
Unit F was previously prepared from d-glucose, d-glucuronic acid, d-galactose, and d-galacturonic acid.
For leading references, see [3][20].

Helvetica Chimica Acta Vol. 87 (2004)
1797
Scheme 1
the 1 ! 3-linked disaccharide 7a as the main product (65%), along with 5% of a
mixture containing the 1 ! 4-linked disaccharide 8a. Remarkably, in Et2O solution, the
coupling of 6b with 6e catalyzed by Me3SiOTf furnished the 1 ! 4-linked disaccharide
8a as the major product (64%) accompanied by the 1 ! 3 isomer 7a (21%).
The coupling constant J(1,2C) ˆ 8.4 Hz in 7a confirmed the b-d-glycosidic bond, and the chemical shifts of
C(3E) (d 82.25) and C(4E) (d 70.10) established the 1 ! 3 linkage. The structure 7a was confirmed via acetyl
derivative 7b, the 1H-NMR spectrum of which displayed the HÀC(4E) signal at d 4.85 (at d ca. 3.6 in 7a). The
coupling constant J(1,2C) ˆ 7.4 Hz in 8a confirmed the b-d-glycosidic bond, and the chemical shifts of C(3E) (d
69.80) and C(4E) (d 80.54) indicated the formation of a 1 ! 4-linked disaccharide. In the acetyl derivative 8b the
coupling constant J(1,2C) was 8.1 Hz, in agreement with the b-d-glycosidic bond, and the chemical shifts of
HÀC(3E) (d 5.77) and HÀC(4E) (d 4.38 4.30) established the 1 ! 4 linkage.
t
t
The next task was to remove the BuMe2Si group, leaving the primary BuPh2Si
ether intact. Selective desilylation at the anomeric position of 8b with pyridinium p-
toluenesulfonate [24], I2/MeOH [25], BF3 ¥ Et2O [26], TsOH [27], Me3SiOTf [28],

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Helvetica Chimica Acta Vol. 87 (2004)
Scheme 2
t
t
a) [23]. b) BuMe2SiCl, 1H-imidazole, DMF, 208; 92%. c) MeONa, MeOH, 208; 95%. d) BuPh2SiCl, 1H-
imidazole, DMF, 08; 88%. e) Ac2O, pyridine, 208; 96%. f) Me3SiOTf, 4-ä molecular sieves, CH2Cl2, 08; 65%. g)
Conditions e; 96%. h) Me3SiOTf, 4-ä molecular sieves, Et2O, 08; 64% of 8a, 21% of 7a. i) Conditions e; 96%. j)
Bu4NF, THF, À208; 78%. k) Cl3CN, CH2Cl2, K2CO3, 208; 86%. l) Conditions f; 18%. m) H2N(CH2)2NH2,
BuOH, 908, 12 h; then conditions e; 48%. n) Bu4NF, THF, 208; 61%. o) Conditions e; 77%. p) NH3, pyridine/
dioxane, 08; 42%.
AcOH [26], and KF [29] was not successful. Finally, treatment of 8b with Bu4NF under
carefully controlled conditions (1 equiv., 1m in THF, À208) furnished compound 8c,
which, on treatment with Cl3CCN and K2CO3, yielded donor 8d in a high overall yield
(86%) (Scheme 2). Coupling of 8d with the known acceptor 9 [3] catalyzed by
Me3SiOTf in Et2O/CH2Cl2 5 :1 furnished trisaccharide 10a in only 18% yield, probably
as a result of unfavorable physical properties of 9. Compound 9 is rather polar and only
slightly soluble in Et2O due to the carboxamide group. We also tried CH2Cl2,
ClCH2CH2Cl, THF, and MeCN as solvents, but the yields were even lower than that in

Helvetica Chimica Acta Vol. 87 (2004)
1799
Et2O/CH2Cl2. Treatment of 10a with ethane-1,2-diamine [30] in BuOH, followed by
acetylation afforded a compound in which the phenoxycarbonyl group was also
1
replaced by an acetyl group. The H-NMR spectrum of this compound, which we
assume to have structure 10b, did not show the number of acetyl groups conclusively. To
improve the characterization, the silyl ether moiety was cleaved with Bu4NF in THF to
1
give 10c. Subsequent acetylation yielded 10d. The H-NMR spectrum of 10c showed
seven acetyl groups. Aromatic proton signals were absent. In agreement with this
‡
result, the 1H-NMR spectrum of 10d displayed eight acetyl signals (ESI-MS: [M ‡ H]
at m/z 932.35186).
Since the phenyl carbonate group did not survive the phthaloyl-group removal from
10a, we converted it to a carbamoyl group by treatment with ammonia/dioxane/
pyridine [3] to give 10e. We then tried to remove the phthalimido group of 10e with
hydrazinium acetate [31], 40% MeNH2/H2O [32] or ethane-1,2-diamine [30] but
neither reagent was successful. In all cases, the carbamoyl group was also removed, and,
after acetylation, compound 10b was obtained.
The results demonstrated that the combination of the Phth protecting group with
either a phenyl carbonate or a urethane group at C(3F) is not compatible in the
synthesis of moenomycin-type oligosaccharides.
Synthesis of a Moenomycin-Type Trisaccharide via a New Unit-F Acceptor. The
low yield (18%) in the coupling of 8d with 9 demanded to use a more suitable acceptor
containing, instead of the amide group, a functional group easily convertible into the
uronamide. The modified glucuronolactone 12b seemed to fulfill these requirements
(Scheme 3). Compound 12b was obtained by allylation at the anomeric position of 12a
in the presence of camphorsulfonic acid, 12a being prepared by removing the
isopropylidene acetal moiety in 11 with 90% CF3COOH/H2O [33].
1
The H- and 13C-NMR spectra ((D5)pyridine) showed 12a to be a 4 :1 mixture of the b- and a-d-isomers.
The 1H- and 13C-NMR signals of C(1) of the b-d-isomer appeared at d 6.10 and 105.71, respectively, and those of
1
the a-d-isomer at d 5.97 and 100.16, respectively. The H- and 13C-NMR spectra of the allylation product 12b
(HÀC(1) at d 6.15 (s), C(1) at d 107.44) indicated that only the b-d-glycoside 12b had been formed [34].
Coupling of donor 8d with 12b catalyzed by Me3SiOTf in Et2O furnished
trisaccharide 13 (42%) (Scheme 3). The yield was lower when CH2Cl2 or ClCH2CH2Cl
were used as solvents. Treatment of 13 with NH3 in THF/MeOH furnished
glucofuranosiduronamide 14a. We also tried NH3 in THF, pyridine, 1,4-dioxane/
pyridine or (NH4)2CO3 in DMF, but under all these conditions, yields were lower due to
the formation of deacetylation products. Silylation of 14a at the C(3F) position with a
t
large excess of BuMe2SiCl in pyridine, catalyzed by N,N-dimethylpyridin-4-amine
t
(DMAP), provided compound 14b (1H-NMR: BuMe2Si at d 0.92, 0.25, and 0.24).
Phthaloyl-group removal with ethane-1,2-diamine in BuOH [23] followed by acetyla-
tion converted 14b into compound 14c. Unexpectedly, the tBuMe2Si group of 14b was
t
replaced by an acetyl group in 14c (1H-NMR: 7 Ac; no BuMe2Si).
We concluded from these results that the new approach was promising but that the
phthaloyl group had to be replaced by more-suitable protecting groups prior to
introduction of the carbamoyl group or a synthetic equivalent. This will be described in
the subsequent communication [35].

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Helvetica Chimica Acta Vol. 87 (2004)
Scheme 3
a) CF3COOH/H2O 9 :1, 208; 92%. b) Allyl alcohol, camphorsulfonic acid, 208; 49%. c) Me3SiOTf, 4-ä
molecular sieves, Et2O, 208; 42%. d) NH3, THF/MeOH, 08; 43%. e) tBuMe2SiCl, pyridine, DMAP, 208, 74%. f)
H2N(CH2)2NH2, BuOH, 908, 12 h; then Ac2O, pyridine, 208; 51%.
Financial support by the Deutsche Forschungsgemeinschaft, Sandoz Industrial Products GmbH (formerly
BC Biochemie GmbH), and the Fonds der Chemischen Industrie is gratefully acknowledged.
Experimental Part
General. See [36].
(tert-Butyl)dimethylsilyl 3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranoside (6c). To a soln. of
6a (500.0 mg, 1.15 mmol) in dry DMF (5.0 ml), 1H-imidazole (156.0 mg, 2.30 mmol) and (tert-butyl)dimethyl-
silyl chloride (230.0 mg, 1.50 mmol) were added at 08. The mixture was stirred at 208 for 4 h (TLC (petroleum
ether/AcOEt 1:1) monitoring). The reaction was stopped by adding MeOH (0.10 ml), the mixture evaporated,
the residue dissolved in AcOEt (30 ml), the soln. washed with 5% NaCl soln., the org. phase dried (Na2SO4)
and evaporated, and the residue purified by FC (petroleum ether/AcOEt 2 :1): 6c (580.2 mg, 92%). M.p. 140.8
141.98 (petroleum ether/AcOEt). Rf (petroleum ether/AcOEt 1:1): 0.62. [a]2D6 ˆ‡ 9 2 (c ˆ 1.0, CHC3). 1H-NMR

Helvetica Chimica Acta Vol. 87 (2004)
1801
(1H,1H-COSY; 300 MHz, CDCl3): 7.86 7.73 (m, PhthN); 5.84 (dd, HÀC(3)); 5.56 (d, HÀC(1)); 5.12 (dd,
HÀC(4)); 4.26 (dd, HÀC(2)); 4.25 (dd, HaÀC(6)); 4.15 (dd, HbÀC(6)); 3.92 3.86 (m, HÀC(5)); 2.09, 2.03, 1.86
(3 s, 3 MeCO); 0.68 (s, Me3C); 0.05, À0.06 (2 s, 2 Me); J(1,2) ˆ 8.1, J(2,3) ˆ 11.2, J(3,4) ˆ 9.0, J(4,5) ˆ 10.2,
J(5,6a) ˆ 5.7, J(5,6b) ˆ 2.4, J(6a,6b) ˆ 12.0. 13C-NMR (13C,1H-COSY; 75.5 MHz, CDCl3): 170.65, 170.18, 169.61
(3 MeCO); 134.36, 131.40, 123.52 (PhthN); 93.22 (C(1)); 71.87 (C(5)); 70.58 (C(3)); 69.54 (C(4)); 62.45 (C(6));
56.74 (C(2)); 25.31 (Me3C); 20.77, 20.70, 20.55 (3 MeCO); 17.57 (Me3C); À4.31, À5.51 (2 Me). ESI-MS
‡
(C26H35NO10Si; 549.65, 549.20): 571.8 ([M ‡ Na] ).
(tert-Butyl)dimethylsilyl 2-Deoxy-2-phthalimido-b-d-glucopyranoside (6d). To a soln. of 6c (450.0 mg,
0.82 mmol) in MeOH (5.0 ml), 1m NaOMe (0.05 ml) was added. The mixture was stirred at 208 for 4 h (TLC
‡
(AcOEt) monitoring). The mixture was neutralized with Dowex 50 W X2 (H form) and filtered and the resin
washed with MeOH. The combined filtrate and washings were evaporated. Purification by FC (CHCl3/MeOH
20 :1) afforded compound 6d (330.2 mg, 95%). M.p. 211.0 211.48 (AcOEt). Rf (petroleum ether/AcOEt 1:3):
0.08. [a]2D6 ˆ À28 (c ˆ 1.0, MeOH). 1H-NMR (1H,1H-COSY; 300 MHz, (D5)pyridine): 7.88 7.57 (m, PhthN);
5.98 (d, HÀC(1)); 5.20 (dd, HÀC(3)); 4.79( dd, HÀC(2)); 4.52 (dd, HaÀC(6)); 4.40 (dd, HbÀC(6)); 4.32 (t,
HÀC(4)); 4.11 4.05 (m, HÀC(5)); 0.78 (s, Me3C); 0.19. 0.10 (2 s, 2 Me); J(1,2) ˆ 8.4, J(2,3) ˆ 10.6, J(3,4) ˆ 8.7,
J(4,5) ˆ 8.7, J(5,6a) ˆ 2.2, J(5,6b) ˆ 4.8, J(6a,6b) ˆ 11.6. 13C-NMR (13C,1H-COSY; 75.5 MHz, (D5)pyridine):
134.03, 131.89, 123.05 (PhthN); 94.02 (C(1)); 78.55 (C(5)); 72.31 (C(4)); 71.92 (C(3)); 62.12 (C(6)); 60.40
(C(2)); 25.17 (Me3C); 17.42 (Me3C); À4.30, À5.72 (2 Me). ESI-MS (C20H29NO7Si; 423.54, 423.17): 445.8 ([M ‡
‡
Na] ).
(tert-Butyl)dimethylsilyl 6-O-[(tert-Butyl)diphenylsilyl]-2-deoxy-2-phthalimido-b-d-glucopyranoside (6e).
To a soln. of 6d (300.0 mg, 0.71 mmol) and 1H-imidazole (100.0 mg, 1.5 mmol) in dry DMF (5.0 ml), (tert-
butyl)diphenylsilyl chloride (0.22 ml, 0.85 mmol) was added dropwise at 08. The mixture was stirred at 08 for 2 h
(TLC (petroleum ether/AcOEt 1:1) monitoring). Workup as described for 6c afforded 6e (413.0 mg, 88%). Rf
(petroleum ether/AcOEt 1.5 :1): 0.40. [a]D26 ˆ À27 ꢀc ˆ 1.0, CHCl3). 1H-NMR (1H,1H-COSY; 300 MHz, CDCl3):
7.81 7.39( m, 2 Ph, PhthN); 5.39( d, HÀC(1)); 4.41 (ddd, HÀC(3)); 4.08 (dd, HÀC(2)); 3.98 3.88 (m, CH2(6));
3.70 (dt, HÀC(4)); 3.63 3.50 (m, HÀC(5)); 3.39( d, OHÀC(4)); 3.13 (d, OHÀC(3)); 1.07 (s, tBuPh2Si); 0.66 (s,
tBuMe2Si); 0.03, À0.09(2 s, 2 Me); J(1,2) ˆ 8.0, J(2,3) ˆ 11.0, J(3,4) ˆ 8.0, J(4,5) ˆ 8.0, J(3,OH) ˆ 4.4,
J(4,OH) ˆ 2.2. 13C-NMR (13C,1H-COSY; 75.5 MHz, CDCl3): 135.88 123.57 (PhthN, 2 Ph); 93.64 (C(1)); 75.12
(C(5)); 74.38 (C(4)); 71.73 (C(3)); 65.14 (C(6)); 58.77 (C(2)); 27.07 (Me3C (tBuPh2Si)); 25.60 (Me3C
(tBuMe2Si)); 19.46 (Me3C (tBuPh2Si)); 17.78 (Me3C (tBuMe2Si)); À3.87, À5.30 (2 Me). ESI-MS (acetone/H2O/
‡
NH4CO3; C36H47NO7Si2; 661.94, 661.29): 679.32290 ([M ‡ NH4] ; calc. 679.32293).
(tert-Butyl)dimethylsilyl 3,4-Di-O-acetyl-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-b-d-gluco-
pyranoside (6f). Compound 6e (300.0 mg, 0.45 mmol) was treated with Ac2O (0.40 ml) and pyridine (0.60 ml) at
208 overnight. The solvents were removed by azeotropic evaporation with toluene. Purification by FC
(petroleum ether/AcOEt 4 :1) afforded 6f (324.3 mg, 96%). M.p. 142.2 142.88 (petroleum ether/AcOEt). Rf
(petroleum ether/AcOEt 1 :1): 0.78. [a]D26 ˆ À27 (c ˆ 1.0, CHCl3). 1H-NMR (1H,1H-COSY; 300 MHz, CDCl3):
7.87 7.36 (m, 2 Ph, PhthN); 5.86 (dd, HÀC(3)); 5.60 (d, HÀC(1)); 5.20 (t, HÀC(4)); 4.31 (dd, HÀC(2)); 3.97
t
t
3.82 (m, HÀC(5), CH2(6)); 1.87 (s, 2 MeCO); 1.08 (s, BuPh2Si); 0.72 (s, BuMe2Si); 0.14, À0.01 (2 s, 2 Me);
J(1,2) ˆ 8.2, J(2,3) ˆ 11.0, J(3,4) ˆ 9.2, J(4,5) ˆ 9,2. 13C-NMR (13C,1H-COSY, 75.5 MHz, CDCl3): 170.64, 169.67
(2 MeCO); 135.96 123.75 (2 Ph, PhthN); 93.51 (C(1)); 75.25 (C(5)); 71.24 (C(3)); 69.78 (C(4)); 63.08 (C(6));
57.20 (C(2)); 26.99 (Me3C (tBuPh2Si)); 25.64 (Me3C (tBuMe2Si)); 20.90, 20.87 (2 MeCO); 19.44 (Me3C
(tBuPh2Si)); 17.83 (Me3C (tBuMe2Si)); À3.84, À5.23 (2 Me). ESI-MS (acetone/H2O/NH4HCO2; C40H51NO9Si2;
‡
746.02, 745.31): 763.34397 ([M ‡ NH4] ; calc. 763.34406).
Reaction of 6b with 6e: 7a and 8a. a) In CH2Cl2. To a soln. of 6e (200.0 mg, 0.30 mmol) and 6b (200.0 mg,
0.35 mmol) in dry CH2Cl2 (5.0 ml), 4-ä molecular sieves (150.0 mg) were added. The mixture was stirred at 208
for 1 h under Ar and then cooled to 08. Me3SiOTf in dry CH2Cl2 (1m; 45 ml, 45 mmol) was added and the mixture
stirred at 08 for 30 min (TLC (petroleum ether/AcOEt 2 :1) monitoring). The reaction was stopped by adding
Et3N (20 ml), the mixture filtered, and the filter cake washed with CH2Cl2. The combined filtrate and washings
were washed with sat. NaHCO3 soln. and H2O. The org. phase was dried (Na2SO4) and evaporated. Purification
by FC (petroleum ether/AcOEt 1.5 :1) afforded 7a (212.0 mg, 65%) and a mixture of three compounds (1 ! 4-
linked disaccharide 8a, 6e, and the decomposed donor in a 2.5 :1:1 ratio; 5%).
b) In Et2O. As described in a), with 6e (200.0 mg, 0.30 mmol), 6b (200.0 mg, 0.35 mmol), dry Et2O (5.0 ml),
4-ä molecular sieves (150.5 mg), and Me3SiOTf (8 ml), 45 (mmol). FC (petroleum ether/AcOEt 2 :1) afforded
8a (210.6 mg, 64%) and 7a (70.0 mg, 21%).
Data of (tert-Butyl)dimethylsilyl 6-O-[(tert-Butyl)diphenylsilyl]-2-deoxy-2-phthalimido-3-O-(3,4,6-tri-O-
acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl)-b-d-glucopyranoside (7a): Rf (petroleum ether/AcOEt

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Helvetica Chimica Acta Vol. 87 (2004)
1.5 :1): 0.31. 1H-NMR (1H,1H-COSY; 300 MHz, CDCl3): 7.72 7.36 (m, 2 Ph, 2 Phth); 5.56 (dd, HÀC(3C)); 5.41
(d, HÀC(1C)); 5.15 (d, HÀC(1E)); 5.06 (t, HÀC(4C)); 4.60 (m, HÀC(3E)); 4.30 (dd, HÀC(2C)); 4.21 4.18 (m,
CH2(6C)); 4.03 (dd, HÀC(2E)); 4.00 3.84 (m, HÀC(5C), CH2(6E), OHÀC(4E)); 3.61 3.50 (m, HÀC(4E),
t
t
HÀC(5E)); 2.02, 1.99, 1.72 (3 s, 3 MeCO); 1.04 (s, BuPh2Si); 0.53 (s, BuMe2Si); 0.01, À0.20 (2 s, 2 Me);
J(1E,2E) ˆ 8.1, J(2E,3E) ˆ 10.6, J(3E,4E) ˆ 7.4, J(4E,OH) ˆ 1.0, J(1C,2C) ˆ 8.4, J(2C,3C) ˆ 10.6, J(3C,4C) ˆ
9.2, J(4C,5C) ˆ 9.2. 13C-NMR (13C,1H-COSY; 75.5 MHz, CDCl3): 170.69, 169.98, 169.45 (3 MeCO); 135.78,
135.75, 134.15, 133.70, 133.66, 130.94, 129.64, 127.73, 123.20 (2 Ph, 2 PhthN); 98.37 (C(1C)); 93.41 (C(1E)); 82.25
(C(3E)); 76.92 (C(5E)); 71.98 (C(5C)); 70.49(C(3 C)); 70.10 (C(4E)); 69.02 (C(4C)); 63.77 (C(6E)); 62.21 (C(6C));
57.55 (C(2E)); 54.59(C(2 C)); 26.92 (Me3C (tBuPh2Si)); 25.27 (Me3C (tBuMe2Si)); 20.67, 20.67, 20.34 (3 MeCO);
19.39 (Me3C (tBuPh2Si)); 17.39(Me 3C (tBuMe2Si)); À4.03, À5.67 (2 Me). ESI-MS (C56H66N2O16Si2; 1079.31,
‡
1078.40): 1101.38162 ([M ‡ Na] : calc. 1101.38431).
Data of (tert-Butyl)dimethylsilyl 6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-4-O-(3,4,6-tri-O-
acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl)-b-d-glucopyranoside (8a). Rf (petroleum ether/AcOEt
1
1.5 :1): 0.40. [a]2D6 ˆ ‡25 (c ˆ 1.0, CHCl3). H-NMR (1H,1H-COSY; 300 MHz, CDCl3): 7.84 7.35 (m, 2 PhthN,
2 Ph); 5.72 (dd, HÀC(3C)); 5.60 (d, HÀC(1C)); 5.36 (d, HÀC(1E)); 5.06 (t, HÀC(4C)); 4.47 (dd, HÀC(3E)); 4.29
(dd, HÀC(2C)); 4.21 4.08 (m, HÀC(2E)); CH2(6C)); 3.94 3.83 (m, HÀC(4E), HÀC(5E), HÀC(5C)); 3.68 (dd,
t
HaÀC(6E)); 3.53 3.48 (m, HbÀC(6E), OHÀC(3)); 2.01, 1.90, 1.80 (3 s, 3 MeCO); 0.97 (s, BuPh2Si); 0.62 (s,
tBuMe2Si); À0.09, À0.18 (2 s, 2 Me); J(1E,2E) ˆ 7.4, J(2E,3E) ˆ 9.0, J(3E,4E) ˆ 9.2, J(5E,6aE) ˆ 4.2,
J(6aE,6bE) ˆ 13.2, J(1C,2C) ˆ 7.4, J(2C,3C) ˆ 9.0, J(3C,4C) ˆ 10.5, J(4C,5C) ˆ 10.5. 13C-NMR (13C,1H-COSY;
75.5 MHz, CDCl3): 170.55, 170.06, 169.55 (3 MeCO); 135.79, 135.75, 134.33, 134.13, 133.33, 131.93, 130.95,
129.66, 127.78, 127.73, 123.72 (2 Ph, 2 PhthN); 98.06 (C(1C)); 93.12 (C(1E)); 80.54 (C(4E)); 75.10 (C(5C)); 72.08
(C(5E)); 70.62 (C(3C)); 69.80 (C(3E)); 69.06 (C(4C)); 62.94 (C(6E)); 62.21 (C(6C)); 58.32 (C(2E)); 54.84 (C(2C));
26.95 (Me3C (tBuPh2Si)); 25.38 (Me3C (tBuMe2Si)); 20.70, 20.47, 20.43 (3 MeCO), 19.56 (Me3C (tBuPh2Si));
17.56 (Me3C (tBuMe2Si)); À4.17, À5.66 (2 Me). ESI-MS (from acetone/H2O/NH4HCO2; C56H66N2O16Si2;
‡
1079.31, 1078.40): 1096.42806 ([M ‡ NH4] , calc. 1096.42891).
(tert-Butyl)dimethylsilyl 4-O-Acetyl-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-3-O-(3,4,6-tri-
O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl)-b-d-glucopyranoside (7b). As described for 6f, with 7a
(18.0 mg, 17 mmol), Ac2O (0.20 ml), and pyridine (0.30 ml). FC (petroleum ether/AcOEt 1.5 :1) afforded 7b
(18.0 mg, 96%). Rf (petroleum ether/AcOEt 1.5 :1): 0.38. 1H-NMR (1H,1H-COSY; 300 MHz, CDCl3): 7.86 7.30
(m, 2 Ph, 2 PhthN); 5.47 (dd, HÀC(3C)); 5.21 (d, HÀC(1C)); 5.14 (d, HÀC(1E)); 5.09( t, HÀC(4C)); 4.92 (t,
HÀC(3E)); 4.85 (t, HÀC(4E)); 4.47 (dd, HaÀC(6C)); 4.13 (dd, HÀC(2C)); 4.05 (d, HbÀC(6C)); 4.02 (dd,
HÀC(2E)); 3.79 3.59 ( m, HÀC(5C), HÀC(5E), CH2(6E)); 2.11, 1.95, 1.92, 1.74 (4 s, 4 MeCO); 1.03 (s,
tBuPh2Si); 0.55 (s, tBuMe2Si); 0.00, À0.17 (2 s, 2 Me); J(1E,2E) ˆ 8.0, J(2E,3E) ˆ 8.6, J(3E,4E) ˆ 8.6,
J(4E,5E) ˆ 8.6, J(1C,2C) ˆ 8.4, J(2C,3C) ˆ 10.6, J(3C,4C) ˆ 9.0, J(4C,5C) ˆ 9.0, J(5C,6aC) ˆ 3.7, J(6aC,6bC) ˆ
12.3. 13C-NMR (75.5 MHz, CDCl3): 170.83, 170.26, 169.60, 169.42 (4 MeCO); 135.89 123.52, 97.59, 93.58
(C(1C), C(1E)); 75.56, 74.93, 71.97, 70.86, 69.99, 68.71 (carbohydrate C); 63.55, 61.90 (C(6C), C(6E)); 58.34, 54.83
(C(2C), C(2E)); 26.95 (Me3 (tBuPh2Si)); 25.39( Me3C (tBuMe2Si)); 20.97, 20.79, 20.78, 20.53 (4 MeCO); 19.36
(Me3C (tBuPh2Si)); 17.52 (Me3C (tBuMe2Si)); À3.97, À5.54 (2 Me). ESI-MS (C58H68N2O17Si2; 1121.35, 1120.41):
‡
1143.39010 ([M ‡ Na] ; calc. 1143.39487).
(tert-Butyl)dimethylsilyl 3-O-Acetyl-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-4-O-(3,4,6-tri-
O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl)-b-d-glucopyranoside (8b). As described for 6f, with 8a
(180.0 mg, 170 mmol), Ac2O (0.40 ml), and pyridine (0.60 ml). FC (petroleum ether/AcOEt 2 :1) afforded 8b
(180.1 mg, 96%). Rf (petroleum ether/AcOEt 1.5 :1): 0.40. [a]2D6 ˆ ‡4 (c ˆ 1.0, CHCl3). 1H-NMR (1H,1H-COSY;
300 MHz, CDCl3): 7.81 7.43 (m, 2 PhthN, 2 Ph); 5.77 (dd, HÀC(3E)); 5.69( dd, HÀC(3C)), 5.56 (d, HÀC(1C));
5.45 (d, HÀC(1E)); 5.09( t, HÀC(4C)); 4.38 4.30 (m, H aÀC(6C), HÀC(4E)); 4.18 (dd, HÀC(2C)); 4.16 (dd,
HÀC(2E)); 4.06 (dd, HbÀC(6C)); 3.86 (br. d, HaÀC(6E)); 3.76 (dd, H bÀC(6E)); 3.66 3.62 (m, HÀC(5C)); 3.49
(dd, HÀC(5E)); 2.07, 2.00, 1.95, 1.82 (4 s, 4 MeCO); 1.11 (s, tBuPh2Si); 0.62 (s, tBuMe2Si); À0.08, À0.20 (2 s, 2
Me); J(1E,2E) ˆ 7.8, J(2E,3E) ˆ 9.0, J(3E,4E) ˆ 10.5, J(5E,6bE) ˆ 3.0, J(6aE,6bE) ˆ 12.0, J(1C,2C) ˆ 8.1,
J(2C,3C) ˆ 9.0, J(3C,4C) ˆ 10.5, J(4C,5C) ˆ 10.5, J(5C,6bC) ˆ 0.8, J(6aC,6bC) ˆ 12.0. 13C-NMR (13C,1H-
COSY; 75.5 MHz, CDCl3): 170.72, 170.25, 170.21, 169.60 (4 MeCO); 136.18, 135.95, 134.38, 133.98, 133.29,
131.47, 129.85, 129.80, 127.85, 127.79, 123.74, 123.74, 123.48 (2 Ph, 2 PhthN); 95.88 (C(1C)); 92.98 (C(1E)); 75.46
(C(5C)); 73.09(C(4 E)); 71.89(C(5 E)); 70.89(C(3 C)); 70.29(C(3 E)); 68.87 (C(4C)); 62.84 (C(6E)); 61.84 (C(6C));
57.50 (C(2E)); 55.08 (C(2C)); 27.12 (Me3C (tBuPh2Si)); 25.39( Me3C (tBuMe2Si)); 20.81, 20.81, 20.77, 20.57 (4
MeCO); 19.79 (Me3C (tBuPh2Si)); 17.59(Me C (tBuMe2Si)); À4.21, À5.58 (2 Me). ESI-MS (C58H68N2O17Si2;
3
‡
1221.35, 1220.41): 1243.39269 ([M ‡ Na] ; calc. 1243.39487).

Helvetica Chimica Acta Vol. 87 (2004)
1803
3-O-Acetyl-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-4-O-(3,4,6-tri-O-acetyl-2-deoxy-2-
phthalimido-b-d-glucopyranosyl)-b-d-glucopyranose (8c). To a soln. of 8b (150.0 mg, 0.14 mmol) in dry THF
(3.0 ml), 1m Bu4NF in THF (0.14 ml, 0.14 mmol) was added at À208. The mixture was stirred at À208 for 5 min,
then diluted with CH2Cl2, and washed with 5% NaCl soln. The org. phase was dried (Na2SO4) and evaporated.
Purification by FC (petroleum ether/AcOEt 1.5 :1) afforded 8c (105.1 mg, 78%). Rf (petroleum ether/AcOEt
2 :1): 0.16. 1H-NMR (300 MHz, CDCl3): 7.88 7.74, 7.52 7.42 (2 m, 2 Phth, 2 Ph); 5.80 (dd, HÀC(3E)); 5.75 (dd,
HÀC(3C)); 5.63 (d, HÀC(1C)); 5.37 5.33 (m, HÀC(1E); OHÀC(1E)); 5.17 (dd, HÀC(4C)); 4.47 (dd,
HaÀC(6C)); 4.26 (dd, HÀC(2C)); 4.25 (t, HÀC(4E)); 4.12 (br. d, HbÀC(6C)); 4.05 (dd, HÀC(2E)); 3.85 3.79( m,
HÀC(5C), HaÀC(6E)); 3.71 (dd, HbÀC(6E)); 3.48 3.44 (m, HÀC(5E)); 2.12, 2.05, 1.99, 1.88 (4 s, 4 MeCO); 1.14
(s, Me3C); J(1E,2E) ˆ 8.4, J(2E,3E) ˆ 9.3, J(3E,4E) ˆ 10.2, J(4E,5E) ˆ 10.2, J(5E,6bE) ˆ 2.4, J(6aE,6bE) ˆ
12.0, J(1C,2C) ˆ 7.4, J(2C,3C) ˆ 9.3, J(3C,4C) ˆ 10.2, J(4C,5C) ˆ 9.0, J(5C,6aC) ˆ 4.5, J(6aC,6bC) ˆ 12.0.
13C-NMR (13C,1H-COSY; 75.5 MHz, CDCl3): 170.68, 170.22, 170.10, 169.57 (4 MeCO); 136.38, 136.07, 134.45,
134.28, 133.93, 133.45, 131.64, 131.44, 129.81, 127.73, 127.61, 123.76, 123.62 (2 Ph, 2 PhthN); 96.59, 92.08 (C(1C),
C(1E)); 75.40, 73.45, 71.92, 70.88, 70.45, 68.81 (carbohydrate C); 62.52, 61.83 (C(6E), C(6C)); 56.76, 55.11 (C(2E),
C(2C)); 27.16 (Me3C); 20.80, 20.71, 20.71, 20.51 (4 Me3CO); 19.59 (Me3C). ESI-MS (C52H54N2O17Si; 1007.09,
‡
1006.32): 1029.31075 ([M ‡ Na] ; calc. 1029.30845).
3-O-Acetyl-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-4-O-(3,4,6-tri-O-acetyl-2-deoxy-2-
phthalimido-b-d-glucopyranosyl)-b-d-glucopyranosyl Trichloroacetimidate (8d). To a soln. of 8c (500.0 mg,
0.50 mmol) in dry CH2Cl2 (15 ml), trichloroacetonitrile (0.50 ml, 5.0 mmol) and K2CO3 (400.0 mg, 2.9mmol)
were added. The mixture was stirred at 208 overnight. The mixture was filtered, and the filter cake was washed
with CH2Cl2. The combined filtrate and washings were evaporated. Purification by FC (petroleum ether/AcOEt
1
2 :1) afforded 8d (510.1 mg, 86%). Rf (petroleum ether/AcOEt 1:1): 0.58. H-NMR (200 MHz, CDCl3): 8.49
(br. s, CˆNH); 7.84 7.25 (m, 2 Phth, 2 Ph); 6.53 (d, HÀC(1E)); 5.81, 5.78 (2 t, HÀC(3E), HÀC(3C)); 5.62 (d,
HÀC(1C)); 5.13 (t, HÀC(4C)); 4.49( dd, HÀC(2E)); 4.47 4.41 (m, HÀC(4E), HaÀC(6C)), 4.23 (dd, HÀC(2C));
4.07 (dd, HbÀC(6C)); 3.88 (br. d, HaÀC(6E)); 3.80 3.70 (m, HÀC(5C), HbÀC(6E)); 3.62 3.58 (m, HÀC(5E));
2.10, 2.01, 1.99, 1.843 (4 s, 4 MeCO); 1.10 (s, Me3C); J(1E,2E) ˆ 9.0, J(2E,3E) ˆ 10.8, J(3E,4E) ˆ 10.8,
J(5E,6aE) ˆ 11.2, J(1C,2C) ˆ 8.1, J(2C,3C) ˆ 9.8, J(3C,4C) ˆ 9.8, J(4C,5C) ˆ 9.8, J(5C,6bC) ˆ 1.5,
J(6aC,6bC) ˆ 12.0. 13C-NMR (75.5 MHz, CDCl3): 170.84, 170.34, 170.28, 169.73 (4 MeCO); 160.63 (CˆNH));
136.39, 136.14, 134.57, 133.97, 133.15, 131.54, 129.97, 129.91, 127.96, 127.79, 123.92, 123.90 (2 Ph, 2 PhthN); 96.58,
93.47 (C(1E), C(1C)); 90.65 (CCl3); 76.15, 72.69, 72.13, 70.91, 70.60 (carbohydrate C); 62.15, 62.01 (C(6E),
C(6C)); 55.18, 54.31 (C(2E), C(2C)); 27.15 (Me3C); 20.93, 20.86, 20.81, 20.66 (4 MeCO); 19.88 (Me3C). ESI-MS
‡
(C54H54Cl3N3O17Si; 1151.48, 1149.23): 1172.22233 ([M ‡ Na] ; calc. 1172.21803).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 4)-O-3-O-acetyl-6-O-
[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-b-d-glucopyranosyl]-(1 ! 2)-3-O-(phenoxycarbonyl)-5-O-
prop-2-enyl-a-d-glucofuranosiduronamide (10a). As described for 7a (a)), with 8d (230.0 mg, 0.20 mmol), 9
(100.0 mg, 0.25 mmol), dry CH2Cl2/Et2O 1 :5 (6.0 ml) 4-ä molecular sieves (250.4 mg; 1 h), and 1m Me3SiOTf in
CH2Cl2 (40 ml, 40 mmmol; 4 h). FC (petroleum ether/AcOEt 1:1) afforded 10a (50.0 mg, 18%). Rf (petroleum
ether/AcOEt 1:2): 0.38. 1H-NMR (1H,1H-COSY; 400 MHz, CDCl3): 7.73 7.29( m, 2 Phth, 3 Ph); 6.36 (br. s, 1 H,
NH2); 5.76 5.57 (m, 2 CH2ˆCHCH2); 5.65 (t, HÀC(3E)); 5.59( t, HÀC(3C)); 5.52 (d, HÀC(1E)); 5.51 (d,
HÀC(1C)); 5.29( t, HÀC(3F)); 5.23 (br. s, 1 H, NH2); 5.16 4.97 (m, 2 CH2ˆCH2), 5.04 (t, HÀC(4C)); 4.84 (d,
HÀC(1F)); 4.50 (dd, HÀC(4F)); 4.36 (dd, HÀC(2F)); 4.34 (dd, HaÀC(6C)); 4.27 (t, HÀC(4E)); 4.15 (dd,
HÀC(2E)); 4.12 (dd, HÀC(2C)); 4.05 3.86 (m, 2 CH2ˆCHCH2, HbÀC(6C)); 3.90 (d, HÀC(5F)); 3.80 (br. d,
HaÀC(6E)), 3.70 (dd, HbÀC(6E)), 3.66 3.63 (m, HÀC(5C)); 3.45 3.42 (m, HÀC(5E)); 2.01, 1.93, 1.86, 1.76 (4 s,
4 MeCO); 1.05 (s, Me3C); J(1F,2F) ˆ 4.4, J(2F,3F) ˆ 7.5, J(3F,4F) ˆ 7.5, J(4F,5F) ˆ 4.4, J(1E,2E) ˆ 8.2,
J(2E,3E) ˆ 10.2, J(3E,4E) ˆ 10.2, J(4E,5E) ˆ 10.2, J(5E,6bE) ˆ 1.8, J(6aE,6bE) ˆ 12.0, J(1C,2C) ˆ 8.2,
J(2C,3C) ˆ 10.2, J(3C,4C) ˆ 10.2, J(4C,5C) ˆ 10.2, J(5C,6aC) ˆ 4.2, J(6aC,6bC) ˆ 12.3. 13C-NMR (75.5 MHz,
CDCl3): 172.28, 170.86, 170.39, 170.38, 169.73 (4 MeCO, CONH2); 152.67, 151.44, 136.28 121.73 (arom. C);
118.74, 117.02 (2 CH2ˆCHCH2); 99.31, 97.40, 96.25 (glycosidic C); 79.69, 79.25, 79.07, 76.03, 75.59, 73.65, 72.97,
72.05, 70.94, 70.90, 68.92, 68.90 (carbohydrate C); 62.60, 1.90 (C(6C), C(6E)); 55.23 (C(2C), C(2E)); 27.21
(Me3C); 20.95, 20.88, 20.85, 20.67 (4 MeCO); 19.90 (Me3C). ESI-MS (C71H75N3O24Si; 1382.47, 1381.45):
‡
1382.46293 ([M ‡ Na] ; calc.1382.45878).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-(acetylamino)-2-deoxy-b-d-glucopyranosyl-(1 ! 4)-O-3-O-acetyl-2-
(acetylamino)-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-b-d-glucopyranosyl-(1 ! 2)-3-O-acetyl-5-O-prop-2-enyl-
a-d-glucofuranosiduronamide (10b). To a soln. of 10a (30.0 mg, 22 mmol) in BuOH (8.0 ml) ethane-1,2-diamine
(1.5 ml) was added. The soln. was stirred at 908 for 12 h. After evaporation, the residue was dissolved in pyridine
(4.0 ml) and Ac2O (2.0 ml). The mixture was stirred at 208 overnight. Evaporation and purification by FC

1804
Helvetica Chimica Acta Vol. 87 (2004)
(CHCl3/MeOH 9:1) afforded 10b (12.1 mg, 48%). Rf (CH2Cl2/MeOH 9:1): 0.45. 1H-NMR (300 MHz, CDCl3;
signals that could be assigned): 7.81 7.74 (m, 10 arom H); 5.95 5.81 (m, 2 CH2ˆCHCH2); 2.10, 2.07, 2.07, 2.06,
‡
2.04, 2.03, 2.02 (7s, 7 MeCO); 1.16 (s, Me3C). ESI-MS (C54H73N3O21Si; 1128.27, 1127.45): 1128.45999 ([M ‡ H] ;
‡
calc. 1128.45786), 1150.44112 ([M ‡ Na] ; calc. 1150.43980).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-(acetylamino)-2-deoxy-b-d-glucopyranosyl-(1 ! 4)-O-3-O-acetyl-2-
(acetylamino)-2-deoxy-b-d-glucopyranosyl-(1 ! 2)-3-O-acetyl-5-O-prop-2-enyl-a-d-glucofuranosiduronamide
(10c). To a soln. of 10b (12.0 mg, 11 mmol) in dry THF (1.0 ml), 1m Bu4NF in THF (11 ml) was added. The
mixture was stirred at 208 for 30 min and then evaporated. Purification by FC (CHCl3/MeOH 5 :1) afforded 10c
(6.0 mg, 61%). Rf (CH2Cl2/MeOH 6 :1): 0.36. 1H-NMR (200 MHz, (D5)pyridine; signals that could be assigned):
9.29, 9.20 (2 d, 2 NHAc); 2.17, 2.17, 2.10, 2.10, 2.00, 1.96, 1.96 (7 s, 7 MeCO); J(2,NH) ˆ 7.6. ESI-MS
‡
(C38H55Cl3N3O21; 889.86, 889.33): 890.34135 ([M ‡ H] ; calc. 890.34008).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-(acetylamino)-2-deoxy-b-d-glucopyranosyl-(1 ! 4)-O-3,6-di-O-acetyl-
2-(acetylamino)-2-deoxy-b-d-glucopyranosyl-(1 ! 2)-3-O-acetyl-5-O-prop-2-enyl-a-d-glucofuranosidurona-
mide (10d). As described for 6f, with 10c (6.0 mg, 6.7 mmol), Ac2O (0.40 ml), and pyridine (0.60 ml). FC
(CHCl3/MeOH 5 :1) afforded 10d (5.1 mg, 77%). Rf (CH2Cl2/MeOH 9:1): 0.38. 1H-NMR (200 MHz, CD3OD;
signals that could be assigned): 5.98 5.75 (m, 2 CH2ˆCHCH2); 2.03, 1.99, 1.98, 1.92, 1.91, 1.90, 1.84, 1.82 (8 s, 8
‡
MeCO). ESI-MS (C40H57N3O22 (931.90, 931.34): 932.35186 ([M ‡ H] ; calc 932.35065).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 4)-O-6-O-[(tert-butyl)-
diphenylsilyl]-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 2)-3-O-(aminocarbonyl)-5-O-prop-2-enyl-a-d-
glucofuranosiduronamide (10e). A soln. of 10a (30.0 mg, 22 mmol) in dry pyridine/dioxane 2 :1 (3.0 ml) was
cooled to 08. Gaseous ammonia was bubbled until the starting material disappeared (TLC (petroleum ether/
AcOEt 1:2)). Evaporation and purification by FC (CHCl3/MeOH 120 :1) afforded 10e (12.1 mg, 42%). Rf
1
(petroleum ether/AcOEt 1:2): 0.21. H-NMR (1H,1H-COSY; 600 MHz, CDCl3): 7.78 7.33 (m, 2 Phth, 2 Ph);
6.28 (br. s, 1 H, NH2); 5.70 5.60 (m, 2 CH2ˆCHCH2); 5.68 (t, HÀC(3E)); 5.63 (t, HÀC(3C)); 5.50 (d,
HÀC(1C)); 5.40 (d, HÀC(1E)); 5.12 5.06 (m, CH2ˆCHCH2, HÀC(3F)); 5.05 (t, HÀC(4C)); 5.00 4.93 (m,
CH2ˆCHCH2); 4.79( d, HÀC(1F)); 4.43 (dd, HÀC(4F)); 4.30 (dd, HaÀC(6C)); 4.26 (dd, HÀC(2F)); 4.23 (t,
HÀC(4E)); 4.16 (dd, HÀC(2E)); 4.12 (dd, HÀC(2C)); 4.04 (br. d, HbÀC(6C)); 3.95 3.79 (m, 2 CH2ˆCHCH2,
HaÀC(6E)); 3.76 (d, HÀC(5F)); 3.69( dd, HbÀC(6E)); 3.65 3.63 (m, HÀC(5C)); 3.44 3.41 (m, HÀC(5E)); 1.99,
1.94, 1.89, 1.76 (4 s, 4 MeCO); 1.03 (s, Me3C); J(1F,2F) ˆ 4.2, J(2F,3F) ˆ 8.4, J(3F,4F) ˆ 7.8, J(4F,5F) ˆ 3.1,
J(1E,2E) ˆ 8.4, J(2E,3E) ˆ 9.3, J(3E,4E) ˆ 9.3, J(4E,5E) ˆ 9.3, J(5E,6bE) ˆ 3.7, J(6aE, 6bE) ˆ 12.0,
J(1C,2C) ˆ 8.4, J(2C,3C) ˆ 9.8, J(3C,4C) ˆ 9.8, J(4C,5C) ˆ 9.8, J(5C,6aC) ˆ 4.8, J(6aC,6bC) ˆ 12.5.
5-O-Prop-2-enyl-d-glucofuranosidurono-6,3-lactone (a/b-d-anomers 1:4; 12a). A mixture of 11 (800.0 mg,
3.13 mmol) and 90% CF3COOH/H2O (5.0 ml) was stirred at 208 for 40 min. After evaporation, the residue was
purified by FC (CHCl3/MeOH 5 :1): 12a (620.4 mg, 92%). Rf (AcOEt): 0.10. M.p. 120.8 121.38 (CH2Cl2/
MeOH). [a]2D6 ˆ ‡33 (c ˆ 1.0, MeOH). 1H-NMR (1H,1H-COSY; 300 MHz, (D5)pyridine; b-d-anomer): 6.07 (s,
HÀC(1)); 6.13 5.94 (m, CHˆCH2CH2); 5.44 5.14 (m, CHˆCH2CH2, HÀC(3), HÀC(4)); 4.90 (s, HÀC(2));
4.76 4.40 (m, HÀC(5), CHˆCH2CH2). 13C-NMR (13C,1H-COSY; 50 MHz, (D5)pyridine); b-d-anomer: 173.83
(CO); 135.01 (CHˆCH2CH2); 117.87 (CHˆCH2CH2); 105.63 (C(1)); 85.37 (C(3)); 79.08 (C(2)); 77.29 (C(4));
76.45 (C(5)); 71.91 (CHˆCH2CH2); a-d-anomer: 173.83 (CO); 134.76 (CHˆCH2CH2); 117.87 (CHˆCH2CH2);
100.03 (C(1)); 85.91 (C(3)); 76.60 (C(2)); 75.61 (C(4)); 75.47 (C(5)); 71.91 (CHˆCH2CH2). ESI-MS (C9H12O6;
‡
216.19, 216.06),: 238.8 ([M ‡ Na] ).
Prop-2-enyl 5-O-Prop-2-enyl-b-d-glucofuranosidurono-6,3-lactone (12b). To a soln. of 12a (1.00 g,
4.63 mmol) in prop-2-en-1-ol (20 ml), camphorsulfonic acid (1.00 g, 4.30 mmol) was added. The mixture was
stirred at 208 for 2.5 h (TLC (petroleum ether/AcOEt 1:2) monitoring). The reaction was stopped by adding
pyridine (10 ml). The solvents were removed by azeotropic evaporation with toluene. The residue was diluted
with CHCl3, the soln. washed with aq. NaHCO3 soln. and then with H2O, dried (Na2SO4), and evaporated, and
the residue purified by FC (petroleum ether/AcOEt 1:1): 12b (580.1 mg, 49%). Rf (petroleum ether/AcOEt
1:1.5): 0.33. M.p. 64.7 65.38 (petroleum ether/AcOEt). [a]2D6 ˆ À9 (c ˆ 1.0, CHCl3). 1H-NMR (1H,1H-COSY;
300 MHz, CDCl3): 6.08 5.81 (m, 2 CHˆCH2CH2); 5.45 5.18 (m, 2 CHˆCH2CH2); 5.15 (s, HÀC(1)); 5.05 (dd,
HÀC(4)); 4.90 (d, HÀC(3)); 4.45 (s, HÀC(2)); 4.38 4.29, 3.99 3.92 (2 m, 2 CHˆCH2CH2); 4.23 (d, HÀC(5));
J(3,4) ˆ 5.1, J(4,5) ˆ 6.6. 13C-NMR (13C,1H-COSY; 75.5 MHz, CDCl3): 173.58 (CO); 133.72, 133.63 (2
CHˆCH2CH2); 119.33, 118.33 (2 CHˆCH2CH2); 107.44 (C(1)); 83.78 (C(3)); 77.75 (C(2)); 76.25 (C(4));
‡
74.30 (C(5)); 71.95, 68.78 (2 CHˆCH2CH2). ESI-MS (C12H16O6; 256.26, 256.09): 278.9 ([ M ‡ Na] ).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 4)-O-3-O-acetyl-6-O-
[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-b-d-glucopyranosyl]-(1 ! 2)-5-O-prop-2-enyl-b-d-glucofura-
nosidurono-6,3-lactone (13). As described for 8a (b)), with 8d (200.0 mg, 0.17 mmol), 12b (80.0 mg, 0.31 mmol),

Helvetica Chimica Acta Vol. 87 (2004)
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dry Et2O (5.0 ml), 4-ä molecular sieves (200.4 mg; 1 h), and Me3SiOTf (6.0 ml; 3 h). 13 (96.2 mg, 42%). Rf
1
(petroleum ether/AcOEt 1:2): 0.30. H-NMR (1H,1H-COSY; 400 MHz, CDCl3): 7.87 7.32 (m, 2 Phth, 2 Ph);
6.00 5.81, 5.83 5.71 (2 m, 2 CH2ˆCHCH2); 5.80 (dd, HÀC(3C)); 5.64 (d, HÀC(1C)); 5.61 (dd, HÀC(3E)); 5.52
(d, HÀC(1E)); 5.34 5.09( m, 2 CH2ˆCHCH2); 5.16 (t, HÀC(4C)); 5.09( s, HÀC(1F)); 4.62 (d, HÀC(3F)); 4.56
(dd, HÀC(4F)); 4.46 (dd, HaÀC(6C)); 4.45 (t, HÀC(4E)); 4.31 (s, HÀC(2F)); 4.27 4.18 (m, 2 CH2ˆCHCH2,
HÀC(2E), HÀC(2C)); 4.12 (dd, HbÀC(6C)); 3.99 (d, HÀC(5F)); 3.87 (br. d, HaÀC(6E)); 3.80 3.72 (m,
HÀC(5C); HbÀC(6E)); 3.48 3.45 (m, HÀC(5E)); 2.12, 2.05, 2.00, 1.88 (4 s, 4 MeCO); 1.17 (s, Me3C);
J(3F,4F) ˆ 4.9, J(4F,5F) ˆ 6.6, J(1E,2E) ˆ 8.3, J(2E,3E) ˆ 9.6, J(3E,4E) ˆ 9.6, J(4E,5E) ˆ 9.6, J(6aE,6bE) ˆ
11.6, J(1C,2C) ˆ 8.4, J(2C,3C) ˆ 10.7, J(3C,4C) ˆ 9.1, J(4C,5C) ˆ 9.1, J(5C,6aC) ˆ 5.0, J(5C,6bC) ˆ 1.5,
J(6aC,6bC) ˆ 12.6. 13C-NMR (75.5 MHz, CDCl3): 172.24, 170.74, 170.40, 170.29, 169.71 (4 MeCO, CO) ;
136.22 123.91 (arom. C); 118.88, 117.86 (2 CH2ˆCHCH2); 105.97 (C(1F)); 96.50, 96.45 (C(1C), C(1E)),; 82.99,
80.70, 76.19, 75.90, 74.01, 72.58, 72.06, 71.75, 70.94, 70.84, 68.91, 68.63 (carbohydrate C); 62.24, 61.90 (C(6C),
C(6E)); 55.17 (C(2C), C(2E)); 27.21 (Me3C); 20.89, 20.84, 20.75, 20.63 (4 MeCO); 19.79 (Me3C). ESI-MS
‡
‡
(C64H68N2O22Si; 1245.33, 1244.40): 1245.41563 ([M ‡ H] ; calc. 1245.41057), 1262.44215 ([M ‡ NH4] ; calc.
‡
1262.43712), 1267.39607, ([M ‡ Na] ; calc. 1267.39252).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 4)-O-3-O-acetyl-6-O-
[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 2)-5-O-prop-2-enyl-b-d-glucofura-
nosiduronamide (14a). At 08 13 (100.0 mg, 0.079mmol) was added to a sat. ammonia soln. in THF/MeOH 10 :1
(10 ml). The mixture was stirred at 08 for 1.5 h. The ammonia was removed with a stream of N2 at 08.
Evaporation and purification by FC (CHCl3/MeOH 20 :1) furnished 14a (45.0 mg, 43%). Rf (petroleum ether/
AcOEt 1:2): 0.23. 1H-NMR (300 MHz, CDCl3): 7.89 7.43 ( m, 2 Phth, 2 Ph); 6.55 (br. s, 1 H, NH2); 5.89 5.71
(m, 2 CH2ˆCHCH2); 5.80 (t, HÀC(3C)); 5.66 (t, HÀC(3E)); 5.65 (d, HÀC(1C)); 5.48 (d, HÀC(1E)); 5.40 (br. s,
1 H, NH2); 5.25 5.10 (m, 2 CH2ˆCHCH2, HÀC(4C)); 4.98 (s, HÀC(1F)); 4.50 4.40 (m, HÀC(4E),
HaÀC(6C)); 4.28 3.78 (m, 2 CH2ˆCHCH2, HÀC(2E), HÀC(2C), HÀC(2F), HÀC(3F), HÀC(4F), HÀC(5C),
HÀC(5F), CH2(6E), HbÀC(6C)); 3.47 3.42 (m, HÀC(5E)); 2.12, 2.05, 2.00, 1.88 (4 s, 4 MeCO); 1.17 (s, Me3C);
J(1E,2E) ˆ 8.3, J(2E,3E) ˆ 9.6, J(3E,4E) ˆ 9.6, J(1C,2C) ˆ 8.4, J(2C,3C) ˆ 9.1, J(3C,4C) ˆ 9.1. ESI-MS
‡
(C64H71N3O22Si; 1262.36, 1261.43); 1262.43483 ([M ‡ H] ; calc. 1262.43775).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 4)-O-3-O-acetyl-6-O-
[(tert-butyl)diphenylsilyl]-2-deoxy-2-phthalimido-b-d-glucopyranosyl-(1 ! 2)-5-O-prop-2-enyl-3-O-[(tert-bu-
tyl)dimethylsilyl]-b-d-glucofuranosiduronamide (14b). To a soln. of 14a (100.0 mg, 0.078 mmol) in dry pyridine
t
(1.0 ml), BuMe2SiCl (80.1 mg, 0.53 mmol) and DMAP (5.0 mg) were added. The mixture was stirred at 208
overnight. Evaporation and purification by FC (petroleum ether/AcOEt 1:1) afforded 14b (80.1 mg, 74%). Rf
(petroleum ether/AcOEt 1 :1.5): 0.25. 1H-NMR (300 MHz, CDCl3): 7.88 7.43 (m, 2 Phth, 2 Ph); 6.29(br. s,
NH); 5.83 5.71 (m, 2 CH2ˆCHCH2); 5.80 (dd, HÀC(3C)); 5.65 (t, HÀC(3E)); 5.64 (d, HÀC(1C)); 5.48 (d,
HÀC(1E)); 5.25 5.07 (m, 2 CH2ˆCHCH2, HÀC(4C)); 4.95 (s, HÀC(1F)); 4.48 (dd, HaÀC(6C)); 4.44 (t,
HÀC(4E)); 4.28 3.73 (m, 2 CH2ˆCHCH2, HÀC(2C), HÀC(2E), HÀC(2F), HÀC( 3F), HÀC(4F), HÀC(5C),
HÀC(5F), CH2(6E), HbÀC(6C)); 3.43 3-41 (m, HÀC(5E)); 2.12, 2.05, 2.00, 1.87 (4 s, 4 MeCO); 1.16 (s, Me3C
(tBuPh2Si), 0.92 (s, Me3C (tBuMe2Si); 0.25, 0.24 (2 s, 2 Me); J(1E,2E) ˆ 8.4, J(2E,3E) ˆ 9.3, J(3E,4E) ˆ 9.3,
J(4E,5E) ˆ 9.3, J(1C,2C) ˆ 8.4, J(2C,3C) ˆ 10.5, J(3C,4C) ˆ 9.3, J(5C,6aC) ˆ 1.9, J(6aC,6bC) ˆ 11.9. ESI-MS
‡
(C70H85N3O22Si2; 1376.62, 1375.52): 1376.52107 ([M ‡ H] ; calc. 1376.52423).
Prop-2-enyl O-3,4,6-Tri-O-acetyl-2-(acetylamino)-2-deoxy-b-d-glucopyranosyl)-(1 ! 4)-O-3-O-acetyl-2-
(acetylamino)-6-O-[(tert-butyl)diphenylsilyl]-2-deoxy-b-d-glucopyranosyl]-(1 ! 2)-3-O-acetyl-5-O-prop-2-en-
yl-b-d-glucofuranosiduronamide (14c). As described for 10b, with 14b (80.0 mg, 0.058 mmol), BuOH (2.0 ml),
ethane-1,2-diamine (0.50 ml), pyridine (0.50 ml), and Ac2O (0.30 ml). FC (AcOEt) afforded 14c (36.1 mg,
1
51%). Rf (CH2Cl2/MeOH 10 :1): 0.68. H-NMR (300 MHz, CDCl3; signals that could be assigned): 7.82 7.47
(m, 2 Ph); 2.11, 2.07, 2.04 (3 s, 7 MeCO); 1.15 (s, Me3C (tBuPh2Si)). ESI-MS (C54H73N3O21Si; 1128.27, 1127.45),
‡
‡
1128.46179([ M ‡ H] ; calc. 1128.45786), 1150.44419([ M ‡ Na] ; calc. 1150.43980).
REFERENCES
[1] J. van Heijenoort, Glycobiology 2001, 11, 25R.
[2] M. Terrak, T. K. Ghosh, J. van Heijenoort, J. van Beemen, M. Lampilas, J. Aszodi, J. A. Ayala, J.-M.
¡
Ghuysen, M. Nguyen-Desteche, Mol. Microbiol. 1999, 34, 350, and ref. cit. therein; A. M. Di Guilmi, A.
Dessen, O. Diedeberg, T. Vernet, J. Bacteriol. 2003, 185, 1650; B. Schwartz, J. A. Markwalder, S. P. Seitz, Y.
Wang, R. L. Stein, Biochemistry, 2002, 41, 12552.

1806
Helvetica Chimica Acta Vol. 87 (2004)
[3] N. El-Abadla, M. Lampilas, L. Hennig, M. Findeisen, P. Welzel, D. M¸ller, A. Markus, J. van Heijenoort,
Tetrahedron 1999, 55, 699, and ref. cit. therein.
[4] K. Stembera, S. Vogel, A. Buchynskyy, J. A. Ayala, P. Welzel, ChemBioChem 2002, 3, 559.
[5] A. Anikin, A. Buchynskyy, U. Kempin, K. Stembera, P. Welzel, G. Lantzsch, Angew. Chem. 1999, 111, 3931;
Angew. Chem., Int. Ed. 1999, 38, 3703.
[6] O. Ritzeler, L. Hennig, M. Findeisen, P. Welzel, D. M¸ller, A. Markus, G. Lemoine, M. Lampilas, J. van
Heijenoort, Tetrahedron 1997, 53, 1675.
[7] M. Mayer, B. Meyer, J. Am. Chem. Soc. 2001, 123, 6108, and ref. cit. therein.
[8] M. Vogtherr, T. Peters, J. Am. Chem. Soc. 2000, 122, 6093.
[9] T. R¸hl, M. Daghish, A. Buchynskyy, K. Barche, D. Volke, K. Stembera, U. Kempin, D. Knoll, L. Hennig,
M. Findeisen, R. Oehme, S. Giesa, J. Ayala, P. Welzel, Bioorg. Med. Chem. 2003, 11, 2965.
[10] L. Chen, D. Walker, B. Sun, S. Walker, D. Kahne, Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 5658.
[11] A. A. Branstrom, S. Midha, R. C. Goldman, FEMS Microbiol. Lett. 2000, 191, 187.
[12] R. A. Copeland, −Enzymes×, VCH Publishers, Inc., New York, 1996, p. 225
[13] K. Stembera, A. Buchynskyy, S. Vogel, D. Knoll, A. A. Osman, J. A. Ayala, P. Welzel, ChemBioChem 2002,
3, 332.
[14] S. Vogel, A. Buchynskyy, K. Stembera, K. Richter, L. Hennig, D. M¸ller, P. Welzel, F. Maquin, C.
Bonhomme, M. Lampilas, Bioorg. Med. Chem. Lett. 2000, 10, 1963, and ref. cit. therein
¬
[15] A. Buchynskyy, K. Stembera, D. Knoll, S. Vogel, U. Kempin, A. Biallass (nee Donnerstag), L. Hennig, M.
Findeisen, D. M¸ller, P. Welzel, Tetrahedron 2002, 58, 7741, and ref. cit. therein.
[16] J. L¸ning, U. Mˆller, D. M¸ller, P. Welzel, A. Markus, Y. van Heijenoort, J. van Heijenoort, Tetrahedron
1993, 49, 10587.
[17] G. Range, R. Kr‰hmer, P. Welzel, D. M¸ller, G. F. Herrmann, U. Kragl, A. Markus, C. Wandrey, Y. van
Heijenoort, J. van Heijenoort, Tetrahedron 1997, 53, 1695.
[18] E. R. Baizman, A. A. Branstrom, C. B. Longley, N. Allanson, M. J. Sofia, D. Gange, R. C. Goldman,
Microbiology 2000, 146, 3129.
[19] U. Eichelberger, M. Mansourova, L. Hennig, M. Findeisen, S. Giesa, D. M¸ller, P. Welzel, Tetrahedron
2001, 57, 9737; U. Eichelberger, I. Neundorf, L. Hennig, M. Findeisen, S. Giesa, D. M¸ller, P. Welzel,
Tetrahedron 2002, 58, 545; M. Mansourova, K. Rohr, L. Hennig, M. Findeisen, R. Oehme, S. Giesa, P.
Welzel, Eur. J. Org. Chem. 2003, 2656.
[20] F.-T. Ferse, K. Floeder, L. Hennig, M. Findeisen, P. Welzel, D. M¸ller, J. van Heijenoort, Tetrahedron 1999,
55, 3749.
[21] A. Medgyes, E. Farkas, A. Liptak, V. Pozsgay, Tetrahedron 1997, 53, 4159.
[22] G. Grundler, R. R. Schmidt, Carbohydr. Res. 1985, 135, 203.
[23] W. Kinzy, R. R. Schmidt, Liebigs Ann. Chem. 1985, 8, 1537.
[24] C. Prakash, S. Saleh, I. A. Blair, Tetrahedron Lett. 1989, 30, 19 .
[25] B. H. Lipshutz, J. Keith, Tetrahedron Lett. 1998, 39, 2495.
[26] T. D. Nelson, R. D. Crouch, Synthesis 1996, 1031.
[27] R. K. Boeckman, A. B. Charette, T. Asberom, B. H. Johnston, J. Am. Chem. Soc. 1991, 113, 5337.
[28] V. Bou, J. Vilarrasa, Tetrahedron Lett. 1990, 31, 567.
[29] A. G. Myers, D. Y. Gin, D. H. Rogers, J. Am. Chem. Soc. 1994, 116, 4697.
[30] O. Kanie, S. C. Crawley, M. M. Palcic, O. Hindsgaul, Carbohydr. Res. 1993, 243, 139; C. Unverzagt,
Carbohydr. Res. 1997, 305, 423.
[31] H.-H. Lee, D. A. Schwartz, J. F. Harris, J. P. Carver, J. J. Krepinsky, Can. J. Chem. 1986, 1912.
[32] G. Skorna, R. Stemmer, I. Ugi, Chem. Ber. 1978, 111, 806.
[33] M. Pietraszkiewicz, P. Sinay, Tetrahedron Lett. 1979, 20, 4741.
¬
[34] J. Madaj, A. Trynda, A. Konitz, A. Nowacki, A. Wisniewski, Carbohydr. Res. 1998, 308, 431.
[35] G. Yang, M. Mansourova, L. Hennig, M. Findeisen, R. Oehme, S. Giesa, P. Welzel, Helv. Chim. Acta 2004,
87, 1807.
[36] D. Volke, M. Daghish, L. Hennig, M. Findeisen, S. Giesa, R. Oehme, P. Welzel, Helv. Chim. Acta 2003, 86,
4214.
Received December 17, 2003