Differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-d-glucopyranosyl chlorides and their application in the synthesis of diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside

Article abstract of DOI:10.1016/j.carres.2012.11.020

Four differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-d- glucopyranosyl chlorides were synthesized and used as glycosyl donors in reactions with diosgenin. The following amine group protections were tested: trifluoroacetyl (TFA), 2,2,2-trichloroethoxycarbonyl (Troc), phthaloyl (Phth), and tetrachlorophthaloyl (TCP). Products of glycosylation were deprotected to yield diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside. The efficiency of the procedures is discussed. Additionally, a single-crystal X-ray diffraction analysis for 3,4,6-tri-O-acetyl-2-deoxy-2-tetrachlorophthalimido-β-d- glucopyranosyl chloride is reported. Orientations of the pyranose substituents as well as the planarity of the acetoxy and phthalimide groups in the crystal lattice are discussed. Structural evidence is presented for a mesomeric effect in both groups. The preference of the cis over trans orientation of the acetoxy group is confirmed in the crystal lattice.

Full text of DOI:10.1016/j.carres.2012.11.020

Carbohydrate Research 367 (2013) 10–17
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Note
Differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-D-
glucopyranosyl chlorides and their application in the synthesis of
diosgenyl 2-amino-2-deoxy-b-D-glucopyranoside
⇑
Dorota Bednarczyk, Agata Walczewska, Daria Grzywacz, Artur Sikorski, Beata Liberek , Henryk Myszka
Faculty of Chemistry, University of Gdan´sk, J. Sobieskiego 18, PL-80-952 Gdan´sk, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Four differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-D-glucopyranosyl chlorides were syn-
Received 20 September 2012
Received in revised form 21 November 2012
Accepted 22 November 2012
Available online 2 December 2012
thesized and used as glycosyl donors in reactions with diosgenin. The following amine group protections
were tested: trifluoroacetyl (TFA), 2,2,2-trichloroethoxycarbonyl (Troc), phthaloyl (Phth), and tetrachlor-
ophthaloyl (TCP). Products of glycosylation were deprotected to yield diosgenyl 2-amino-2-deoxy-b-
glucopyranoside. The efficiency of the procedures is discussed. Additionally, a single-crystal X-ray
diffraction analysis for 3,4,6-tri-O-acetyl-2-deoxy-2-tetrachlorophthalimido-b- -glucopyranosyl chloride
D-
D
Keywords:
Saponins
is reported. Orientations of the pyranose substituents as well as the planarity of the acetoxy and phthal-
imide groups in the crystal lattice are discussed. Structural evidence is presented for a mesomeric effect
in both groups. The preference of the cis over trans orientation of the acetoxy group is confirmed in the
crystal lattice.
Amine group protection
Glycosidation
Crystal structure
Geometry of the acetoxy and phthalimide
groups
Ó 2012 Elsevier Ltd. All rights reserved.
Electrons delocalization
2-Amino-2-deoxy-
D
-glucose is widely distributed in living
emulsifiers. But these natural glycosides also display a wide range
of biological activities, including anti-inflammatory, antibacterial,
antiparasitic, antifungal, and antitumor activities.10–13 The yields
of homogenous saponins isolated from nature are rather small.
Therefore, chemical synthesis is necessary to investigate struc-
ture–activity relationships and the mechanisms of action of sapo-
nins.14–20
organisms where it is an important component of oligosaccharides
and glycoconjugates.1 Because of the abundance and biological
importance of 2-amino-2-deoxy-D-glucose, much effort has been
put into developing chemical methods of its glycosidation.2,3 These
methods are often derived from those reported for the ‘usual’ car-
bohydrates. However, the presence of the 2-amino group compli-
cates the typical approach to glycoside bond formation, since this
demands suitable protection of the amino group. Unfortunately,
glycoside bond formation with donors derived from naturally
Diosgenyl 2-amino-2-deoxy-b-D-glucopyranoside (18) is a syn-
thetic saponin, which has not yet been found in nature. The pres-
ence of the amine group in this promising antitumor and
antimicrobial compound creates the opportunity to synthesize its
new analogues with better cytotoxic activity.21 To find the best
procedure for the synthesis of 18 we studied different glycosyl do-
nors, different amine group protections, and a variety of other con-
ditions. Here, we compare the results of diosgenin glycosylation
with differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-
occurring N-acetyl-2-amino-2-deoxy-D-glucose is unsatisfactory.
This usually results in the formation of relatively stable oxazolines
that cannot be converted into aminosugars under mild conditions.
Therefore, various glucosamine donors, with modified or latent
amino functionalities, have been investigated.3,4
Our research aims to synthesize derivatives of diosgenyl 2-ami-
no-2-deoxy-b-
D
-glucopyranoside (18), a compound with promising
D-glucopyranosyl chlorides. These are glycosyl donors typical of
antitumor and antimicrobial activity.5,6 Naturally occurring diosge-
nyl glycosides belong to the group of saponins. These are steroid or
triterpenoid glycosides, widely distributed in plants and certain
marine organisms.7–9 As their name suggests, saponins are natural
surfactants and have been used as detergents, foaming agents, and
the Koenigs–Knorr procedure, the best known method for the
preparation of 1,2-trans-glycosides, which requires silver salts as
promoters. The following N-protection groups were tested
(Fig. 1): trifluoroacetyl (TFA), 2,2,2-trichloroethoxycarbonyl (Troc),
phthaloyl (Phth), and tetrachlorophthaloyl (TCP). Importantly, the
results are useful for the glycosidation of 2-amino-2-deoxysugars
in general. Additionally, a single-crystal X-ray diffraction analysis
⇑
Corresponding author. Tel.: +48 58 5235320; fax: +48 58 5235472.
E-mail addresses: beatal@chemik.chem.univ.gda.pl, beatal@chem.univ.gda.pl
for 3,4,6-tri-O-acetyl-2-tetrachlorophthalimido-b-
D-glucopyrano-
syl chloride is reported. This enables studies of the geometries of
(B. Liberek).
0008-6215/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.carres.2012.11.020

D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
11
O
H3C
H3C
CH3
Cl
O
O
O
O
Cl
Cl
O
-N
-N
-NH-C-CF -NH-C-OCH CCl
3
H3C
3
2
O
O
-NTCP
Cl
-NHTFA
-NHTroc
-ODsg
-NPhth
-O
Figure 1. The abbreviations used.
pyranose ring substituents. Such studies are important and exten-
sively carried out usually by theoretical calculations.22
the latter (5, 6). Additionally, the overall yields are better when
the acetylation is carried out first. The final amounts of 3–6 calcu-
lated with reference to 1 mmol of 1 are 0.81 mM of 3 (pure b),
To introduce the TFAc and Troc protecting groups onto the amine
function of
D
-glucosamine,
D
-glucosamine hydrochloride (1) was
0.68 mM of 4 (pure b), 0.5 mM of 5 (
+ b). These observations clearly also depend on the protecting
groups used.
a + b), and 0.62 mM of 6
first converted into 1,3,4,6-tetra-O-acetyl-b-
D-glucosamine hydro-
(a
chloride (2) as previously reported.5 Product 2 was next acylated
with trifluoroacetic anhydride to give 1,3,4,6-tetra-O-acetyl-2-
To synthesize N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-
D-glucopyranosyl chlorides (7–10) Magnusson’s procedure
deoxy-2-trifluoroacetamido-b-
D
-glucopyranose (3). Acylation of 2
with 2,2,2-trichloroethoxycarbonyl chloride, performed according
described for 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-a,b-D-
to the literature procedure,23 yielded 1,3,4,6-tetra-O-acetyl-2-
galactopyranose was adopted.26 Thus, acetates 3 and 4 were trea-
ted with 1,1-dichloromethyl methyl ether (ꢀ9 equiv) and zinc
deoxy-2-(2,2,2-trichloroethoxycarbonylamino)-b-
D-glucopyranose
(4). The protecting Phth and TCP groups were introduced onto
D
-glu-
chloride (ꢀ0.06 equiv), which gave solely the
a chloride 7 (J1,2
3.6 Hz) (yield 90%) and the a chloride 8 (J1,2 3.6 Hz) (yield 98%),
cosamine directly by reaction with phthalic anhydride and with
3,4,5,6-tetrachlorophthalic anhydride, respectively, followed by
acetylation with acetic anhydride and pyridine. In the first case we
respectively. Both 7 and 8 were of sufficient purity for use in the
glycosylation reaction. In turn, treatment of 5 with 1,1-dichlorom-
ethyl methyl ether (ꢀ9 equiv) and boron trifluoride etherate
(ꢀ4 equiv) yielded 91% of the b chloride 9 (J1,2 9.6 Hz) of sufficient
purity for use in the glycosylation reaction. Recrystallization from
diethyl ether/petroleum ether yielded 80% of crystalline 9. The
analogous reaction of 6 yielded 98% of the b chloride 10 (J1,2
9.2 Hz) of sufficient purity for use in the glycosylation reaction.
Recrystallization from diethyl ether/petroleum ether yielded 67%
of crystalline 10.
adopted the procedure described for
column chromatography obtained 1,3,4,6-tetra-O-acetyl-2-deoxy-
2-phthalimido- -glucopyranose (5) as mixture of anomers
:b = 1:4), yield 50%. Crystallization of this mixture with ethanol
D
-galactosamine24 and after
D
a
(a
provided pure b-anomer, yield 34%. Another methodology, de-
scribed by Dasgupta and Garegg, for obtaining 5 produced only the
b anomer yield 44%.25 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-(3,4,5,6-
tetrachlorophthalimido)-
D
-glucopyranose (6) was synthesized from
OAc
O
AcO
d
OAc
OAc
AcO
OAc
HNTFA
O
AcO
a
3
AcO
OAc
OAc
NH
x HCl
2
O
AcO
AcO
e
2
HNTroc
OH
O
4
HO
OH
OAc
O
O
HO
HO
AcO
AcO
f
OH
b
c
NH
2
HO
OAc
OAc
x HCl
OH
OH
PhthN
NPhth
1
5
OAc
OH
O
O
AcO
AcO
HO
f
HO
NTCP
TCPN
6
a: [5]; b:: 1. MeONa / MeOH, 2. PhthO / Et N;
3
c: 1. MeONa / MeOH, 2. TCPO / Et3N; d: TFAA / Py; e: TrocCl / Py; f: Ac O / Py.
2
1 as previously reported.5 Comparing these two procedures of
obtainingN-protected acetates 3–6, one may see that when the acet-
ylation is carried out first the final products are the pure b anomers
(3, 4). When the N-protection is carried out first the final products
In the next step, the coupling reactions of N-protected 3,4,6-tri-
O-acetyl-2-deoxy-2-amino- -glucopyranosyl chlorides (7–10) and
diosgenin were carried out to obtain the respective N-protected
diosgenyl 3,4,6-tri-O-acetyl-2-deoxy-2-amino-b- -glucopyrano-
sides (11–14). All glycosylations of diosgenin were carried out in
D
D
are the mixtures of
a and b anomers with the clear dominance of

12
D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
the presence of AgOTf used in conjunction with activated and finally
powdered 4 Å molecular sieves in a mixture of CH2Cl2/Et2O for 11
and 12 and in CH2Cl2 for 13 and 14. In such conditions the glycosida-
tions were efficient and stereoselective, providing solely diosgenyl
b-glycosides in yields of 69%, 86%, 99%, and 87% respectively. The
duration of these reactions does not depend on the N-protecting
group or on the anomeric configuration of the respective chlorides.
In all cases glycosylation took about 20 h.
The final steps in the synthesis of 18 require deprotection of
the hydroxyl and amine functions. In principle, the N-protected
per-O-acetyl-D-glucosamine glycosides (11–14) should be
O-deacetylated first. Otherwise, O?N acetyl migration will take
place. Thus, MeONa in MeOH was used to remove O-acetyl
groups in 11 and 13. In this way, 15 and 17 were obtained in
yields of 98% and 76% respectively. The analogous O-deacetyla-
tion of 12 was not carried out since it was previously reported
that the N-Troc group is converted into the corresponding carba-
mate in such basic conditions.27 Therefore, two other procedures
were attempted. One of them involves Et3N in MeOH and pro-
duces 16 (yield 69%) without affecting the N-Troc group. In the
second method, adopted from other N-Troc protected 2-amino-
2-deoxy sugars,27 MeONa was applied together with a guani-
dine/guanidinium nitrate buffer in the mixture of MeOH/CH2Cl2.
Such O-deacetylation also took place without affecting the N-
Troc group and led to 16 (yield 57%). Compounds 15–17 were
N-deprotected in accordance with the groups to be removed.
Thus, the trifluoroacetyl group was readily removed by basic
hydrolysis with NaOH in acetone to give diosgenyl 2-amino-2-
Figure 2. Structure of 10 showing 25% probability displacements for ellipsoids. The
intramolecular C–Hꢁ ꢁ ꢁO interactions are represented by dotted lines; Cg1 and Cg2
denote the ring centroids.
In the case of diosgenyl glycoside 14 we tried to remove the O-
and N-protective groups under the same reaction conditions. With
this end in view, six equivalents of ethylenediamine in ethanol
were used, which led to 18 and 19 in yields of 70% and 29% respec-
tively.5 Such a result indicates that the O?N acetyl migration oc-
curs in the conditions applied. To avoid this, we tested different
excesses of ethylenediamine, but in all cases both 18 and 19 were
obtained. The use of the mixture of CH3CN/THF/EtOH (2:1:1)
instead of ethanol, which was reported for selective N-TCP
deoxy-b-D-glucopyranoside (18) (yield 80%). The 2,2,2-trichloro-
ethoxycarbonyl group was removed with zinc in acetic acid, as
reported for other N-Troc protected compounds.28–30 Unfortu-
nately, this removal of the N-Troc group from 16 was problem-
atic and yielded
a homogeneous mixture of 18 and an
unidentified product. The phthaloyl group was removed by treat-
ment of 17 with excess of ethylenediamine in ethanol to give 18
(yield 81%).
OAc
OAc
OH
O
O
O
AcO
AcO
HO
a
a
c
c
e
h
i
3
4
ODs
ODs
ODs
ODs
ODs
ODs
ODs
ODs
18
18
AcO
AcO
HO
HO
HO
HNTFA
11
OAc
HNTFA
15
OH
HNTFA
Cl
7
OAc
O
O
O
AcO
AcO
HO
HO
HO
AcO
AcO
f or g
HNTroc
HNTroc
Cl
HNTroc
12
OAc
16
OH
8
OAc
O
O
O
AcO
AcO
b
e
d
d
j
5
6
Cl
Cl
18
AcO
AcO
NPhth
NPhth
NPhth
13
OAc
17
OH
9
OH
OAc
O
O
O
O
AcO
AcO
HO
+
AcO
b
j or k
ODs
HO
HO
AcO
NTCP
NTCP
NH
HNAc
2
14
18
19
10
a: Cl CHCOCH / ZnCl / CHCl ; b: Cl CHCOCH / BF x Et O / CHCl ; c: DsOH / AgOTf / CH Cl / Et O; d: DsOH / AgOTf / CH Cl ;
2
3
2
3
2
3
3
2
3
2
2
2
2
2
e: MeONa / MeOH; f: Et N / MeOH; g: guanidine / guanidine x HNO ; h: NaOH / acetone / H O; i: Zn / CH COOH;
3
3
2
3
j: H NCH CH NH / EtOH; k:H NNH x H O / EtOH.
2
2
2
2
2
2
2

D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
13
.
.
.
O
.
H10
R
H2
N1
H4
C13
...
H C
C8
3
.
.
.
R
R
.
C4
C2
O1
C4
H10
C
C
O2
C5
H5
gt(d)
O4
.
.
O
H C
3
C3
..
C1
S
..
..
cis
O6
C5
C3
.
.
C6H3
C20
trans
(a)
(b)
(c)
Figure 3. Newman projections: along the N1–C2 bond in the crystal lattice of 10 (a), along the Ac–O bond of the two orientations of the acetoxy group (R = sugar residue) (b),
along the AcO2–C3 and AcO4–C4 bonds in the crystal lattice of 10 (c), along the C5–C10 bond in the crystal lattice of 10 (d).
deprotection in the presence of O-acetyl groups,31 caused substrate
14 not to react at all. Exclusive synthesis of 18 from 14 was
achieved using hydrazine hydrate in ethanol. In such conditions
18 was obtained in a yield of 97% after column chromatography
and with a 74% yield after crystallization from methanol.
In the crystal structure, the asymmetric part of 3,4,6-tri-O-acet-
yl-2-deoxy-2-(3,4,5,6-tetrachlorophthalimido)-b-D-glucopyranosyl
chloride (10) consists of one molecule of sugar and half a molecule
of disordered solvent (toluene), which lies on the crystallographic
mirror plane (Fig. 2). The arrangement of chloride 10 and toluene
unfavourable, which is due to both electronic and steric interac-
tions.37 This paper provides an additional reason why the acetoxy
group in carbohydrate derivatives prefers the cis over the trans ori-
entation. Thus, the C3–O2–C6–O3 (7.4°), C4–O4–C8–O5 (8.7°), and
C10–O6–C11–O7 (ꢂ2.5°) torsion angles (Table S2) confirm that the
acetoxy groups are almost planar and cis oriented in the crystal lat-
tice of 10. Besides the previously discussed steric and electronic
factors, X-ray analysis of 10 reveals that the cis orientation of the
acetoxy groups enables the carbonyl oxygen atoms to interact pref-
erentially with the pyranose ring hydrogen atoms. These intramo-
in the crystal lattice is determined by the
p
–
p
interactions of the
lecular C–Hꢁ ꢁ ꢁO interactions are illustrated in Figure
2 and
aromatic rings (Fig. S2, Table S4 in Supplementary data). In the
crystal chloride 10 adopts the 4C1 conformation (Fig. 2) with
ring-puckering parameters32,33 Q = 0.602(4) Å, h = 7.9(4) Å, and
Table S3. Because of them the 3-OAc and 4-OAc groups are ori-
ented in such a way that the C6 and C8 carbonyl atoms are almost
eclipsed by the H3 and H4 atoms respectively (Fig. 3c). This is indi-
cated by the C6–O2–C3–C2 torsion angle of ꢂ124.6° and the C8–
O4–C4–C3 torsion angle of 130.9°.
u
= 334(3)°.
Starting analysis of the geometry of 10 from the chloride it is
worth pointing out that the Cl1–C1 bond length of 1.777 Å
The planarity of the acetoxy groups is necessary for the delocal-
ization of the non-carbonyl oxygen lone pair of electrons onto the
carbonyl oxygen atom. Hence, this planarity provides evidence of
the mesomeric effect in the acetoxy group. This effect is addition-
ally illustrated in the crystal lattice of 10 by the C6–O2 (1.337 Å),
C8–O4 (1.353 Å), and C11–O6 (1.200 Å) bond lengths, which are
significantly shorter than the similar C3–O2 (1.435 Å), C4–O4
(1.441 Å), and C10–O6 (1.426 Å) bond lengths. These differences
are due to the partial double-bond character of the shorter bonds
resulting from the mesomeric effect and delocalization of the
electrons.
(Table S2) is typical of the b chlorides in the 4C1 conformation,
where an endo-anomeric effect does not operate. The
a chlorides
are characterized by the Cl1–C1 bond length >1.8 Å.34
The tetrachlorophthalimide group is almost planar and the C2
sugar carbon atom belongs to the plane created by the two fused
rings of the NTCP. This is illustrated by the respective torsion an-
gles, for example, the C2–N1–C13–C14 torsion angle of ꢂ172.7°
(Table S2). The observed planarity implies sp2 hybridization of
the N1 nitrogen atom. Indeed, the C13–N1–C2 (122.8°), C20–N1–
C2 (124.3°), and C20–N1–C13 (112.4°) valence angles confirm the
trigonal planar geometry of this part of the NTCP group. This pla-
narity is necessary for the delocalization of nitrogen lone pair of
electrons onto the carbonyl oxygen atoms. The fact that such delo-
calization occurs is demonstrated by the N1–C13 and N1–C20 bond
lengths, which are 1.392 and 1.388 Å respectively. These are signif-
icantly shorter than the N1–C2 bond length of 1.467 Å, which is
due to the partial double-bond character of the shorter bonds
resulting from the mesomeric effect and delocalization of the
electrons.
With regard to the rotation about the exocyclic C5–C10 bond,
the acetoxymethyl group of 10 adopts the staggered gt conforma-
tion in the crystal lattice (Fig. 3d), which is confirmed by the O1–
C5–C10–O6 torsion angle of 51.2°. Such a conformation is typical
of D-hexopyranoses, which have the C4 substituent oriented both
equatorially and axially.33
1. Experimental
The planar tetrachlorophthalimide group of 10 in the crystal lat-
tice is arranged in such a way that the C13 carbon atom of the TCP
is eclipsed by the glucosamine H2 proton (Fig. 3a). This orientation
is confirmed by the C13–N1–C2–C3 torsion angle of ꢂ122.3° and
the C13–N1–C2–C1 torsion angle of 114.4° (Table S2). Thus, the
NTCP group is almost perpendicular to the pyranose ring. In this
way steric strain is minimized and, moreover, C–Hꢁ ꢁ ꢁO interactions
between the O8 and pyranose H1 atoms and between the O9 and
pyranose H2 atoms are possible.
1.1. General methods
The melting points were uncorrected. The optical rotations
were determined at rt with a Perkin–Elmer polarimeter in a
1-dm tube at the D line of sodium for solution in CHCl3, CH3OH,
or CHCl3/CH3OH (1:1, v/v). The IR spectra were recorded as Nujol
mulls with a Bruker IFS 66 spectrophotometer; 1H and 13C NMR
spectra on a Varian Mercury 400 (400/100 MHz) instrument for
solution in CDCl3, CD3OD, CDCl3/CD3OD (1:1, v/v), or DMSO (inter-
nal Me4Si); elemental analyses were done on a Carlo Erba EA 1108
instrument. Thin-layer chromatography (TLC) was performed on E.
Merck Kieselgel 60 F-254 plates using the eluent systems (v/v) A,
5:1 toluene–ethyl acetate; B, 2:1 toluene–ethyl acetate; C, 1:3
CHCl3–MeOH; D, 4:1 CCl4–acetone; E, 6:1 toluene–ethyl acetate;
F, 10:1 CHCl3–MeOH; G, 8:1 CHCl3–MeOH; H, 7:1 CHCl3–MeOH;
I, 5:1 CHCl3–MeOH, and column chromatography on MN Kieselgel
60 (<0.08 mm) with one of the eluent systems listed above.
In our previous papers, both crystallographic35 and theoreti-
cal,36 we consistently demonstrated that the acetoxy group is pla-
nar starting from the respective pyranose carbon atom. Being
planar, the acetoxy group may adopt two orientations with regard
to the Ac–O bond rotation, in which the carbonyl oxygen is ori-
ented trans or cis to the respective sugar carbon atom (Fig. 3b).
Our studies of peracetylated glycals, based on DFT calculations,
have indicated that the trans orientation of the acetoxy group is

14
D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
1.2. 1,3,4,6-Tetra-O-acetyl-b-
D
-glucosamine hydrochloride (2)
1.6. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-(3,4,5,6-
tetrachlorophthalimido)- ,b- -glucopyranose (6)
a
D
This was synthesized from 1 as previously reported.5
This was synthesized from 1 as previously reported.5
1.3. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-trifluoroacetamido-b-D-
glucopyranose (3)
1.7. 3,4,6-Tri-O-acetyl-2-deoxy-2-trifluoroacetamido-a-D-
glucopyranosyl chloride (7)
This was synthesized from 2 as previously reported.5
Cl2HCOCH3 (0.97 mL, 10.9 mmol) followed by freshly fused
ZnCl2 (10 mg, 0.073 mmol) were added to a solution of 3 (0.5 g,
1.25 mmol) in dry CHCl3 (1.5 mL). After being stirred for 10 min
under N2, the reaction mixture was heated for 1 h at 40 °C. Then
it was diluted with CHCl3 (50 mL), washed with H2O and satd aq
NaHCO3, dried over MgSO4, and concentrated to give crude 7
(0.47 g, 90%, foam) of sufficient purity for use in the glycosylation
1.4. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-(2,2,2-
trichloroethoxycarbonylamino)-b-D-glucopyranose (4)
This was synthesized from 2 (2.22 g, 5.8 mM) according to the
literature procedure.23 Purification with column chromatography
(solvent A) gave 4 (2.33 g, 77%): mp 123–125 °C, lit.23 mp 125–
126 °C; ½a 2D0
ꢃ
+15 (c 0.5, CHCl3), lit.21 +14 (c 0.9, CHCl3); Rf 0.53 (sol-
reaction: ½a 2D0
ꢃ
ꢂ88 (c 0.5, CHCl3); Rf 0.63 (solvent B); IR:
m 3310 (N–
vent B); IR:
m
3379 (N–H), 1751 (acetyl C@O), 1718 (Troc C@O),
H), 1748 (acetyl C@O), 1729 (TFAc C@O), 1554 cmꢂ1 (–NH, C–N);
1H NMR (400 MHz, CDCl3): d 7.29 (d, 1H, NH), 6.19 (d, 1H, J1,2
3.6 Hz, H-1), 5.41 (dd, 1H, J3,4 10.0 Hz, H-3), 5.16 (dd, 1H, J4,5
1536 cmꢂ1 (–NH, C–N); the 1H NMR (400 MHz, CDCl3) data were
identical with those of presented in Ref. 22; 13C NMR (100 MHz,
0
CDCl3):
d
171.11, 170.65, 169.65, 169.50, (4 ꢄ acetyl C@O),
9.6 Hz, H-4), 4.49 (m, 1H, J2,3 10.8 Hz, H-2), 4.27 (dd, 1H, J6,6
0
154.40 (Troc C@O), 92.50 (C-1), 74.68 (Troc CH2), 72.99 (C-5),
72.29 (C-3), 68.18 (C-4), 61.81 (C-6), 55.27 (C-2), 21.06, 20.94,
20.83, 20.80 (4 ꢄ acetyl CH3); Anal. Calcd for C17H22Cl3NO11: C,
39.06; H, 4.24; N, 2.68. Found: C, 39.10; H, 4.24; N, 2.65.
13.6 Hz, H-6), 4.27 (m, 1H, J5,6 4.0, J5,6 2.8 Hz, H-5), 4.08 (dd, 1H,
H-60), 2.04, 1.98, 1.97 (3 s, 9H, 3 ꢄ OAc); 13C NMR (100 MHz,
CDCl3): d 171.54, 170.63, 169.30 (3 ꢄ COCH3), 157.57 (q, JC,F
37.8 Hz, COCF3), 115,55 (q, JC,F 285.6 Hz, COCF3), 92.00 (C-1),
71.10 (C-5), 69.82 (C-3), 67.10 (C-4), 61.13 (C-6), 53.94 (C-2),
20.68, 20.48, 20.37 (3 ꢄ COCH3).
1.5. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-phthalimido-a,b-D-
glucopyranose (5)
1.8. 3,4,6-Tri-O-acetyl-2-deoxy-2-(2,2,2-
D-Glucosamine hydrochloride (2.73 g, 12.6 mmol) was added to
trichloroethoxycarbonylamino)-a-D-glucopyranosylchloride (8)
a NaOMe solution prepared from Na (0.29 g, 12.6 mmol) and
MeOH (12.6 mL) with simultaneous stirring. After 7 min the resul-
tant NaCl was filtered and washed with MeOH. The filtrate was
treated with phthalic anhydride (0.93 g, 6.3 mmol) and stirred.
After 15 min the reaction mixture was treated again with the anhy-
dride (1 g, 6.7 mmol) and with Et3N (1.8 mL, 13 mmol). Then the
mixture was stirred for 2 h at 50 °C; the end of reaction was de-
tected by TLC (solvent C). After cooling to about 5 °C diethyl ether
(50 mL) was added to the reaction mixture. The precipitate was
treated with pyridine (40 mL) and Ac2O (23 mL) at rt for 20 h. Then
the solution was poured into ice-water and the aqueous mixture
extracted with CHCl3 (3 ꢄ 50 mL). The organic extracts were com-
bined and washed with H2O (30 mL), satd aq NaHCO3 (2 ꢄ 50 mL),
and H2O (50 mL). The organic layer was dried with Na2SO4, filtered,
and the solvent evaporated. The residue was chromatographed
Cl2HCOCH3 (0.5 mL, 5.62 mmol) followed by freshly fused ZnCl2
(5 mg, 0.037 mmol) were added to solution of (0.3 g,
a
4
0.57 mmol) in dry CHCl3 (0.8 mL). After being stirred for 10 min
under N2, the reaction mixture was stirred for 1 h at rt. Then it
was diluted with CHCl3 (50 mL), washed with H2O and satd aq
NaHCO3, dried over MgSO4, and concentrated to give crude 8
(0.28 g, 98%, foam) of sufficient purity for use in the glycosylation
reaction: ½a 2D0
ꢃ
ꢂ81 (c 0.5, CHCl3); Rf 0.67 (solvent B); IR:
m 3329 (N–
H), 1749 (acetyl and Troc C@O), 1536 cmꢂ1 (–NH, C–N); 1H NMR
(400 MHz, CDCl3): d 6.20 (d, 1H, J1,2 3.6 Hz, H-1), 5.41 (d, 1H,
NH), 5.37 (dd, 1H, J3,4 10.0 Hz, H-3), 5.21 (dd, 1H, J4,5 9.6 Hz, H-
4), 4.82 (d, 1H, Cl3CCH2), 4.46 (d, 1H, Cl3CCH2), 4.30 (m, 3H, J2,3
10.0 Hz, J5,6 4.0, J6,6 11.6 Hz, H-2, H-5, H-6), 4.14 (dd, 1H, H-60),
0
2.11, 2.06, 2.05 (3 s, 9H, 3 ꢄ OAc); 13C NMR (100 MHz, CDCl3): d
171.22, 170.75, 169.46 (3 ꢄ ester C@O), 154.28 (amide C@O),
93.54 (C-1), 74. 96 (Troc CH2), 71.16 (C-5), 70.10 (C-3), 67.27 (C-
4), 61.33 (C-6), 55.71 (C-2), 20.75 (ester CH3).
(solvent A) to yield 5 as a mixture of anomers (a:b = 1:4) (3.0 g,
50%). Crystallization of 5 with EtOH yielded the b anomer (2.06 g,
34%): mp 90–94 °C, lit.25 mp 90–94 °C; ½a D20
ꢃ
+59 (c 0.5, CHCl3),
lit.25 +65.5 (c 1.0, CHCl3); Rf 0.38 (solvent A); 1H NMR (100 MHz,
CDCl3): d 7.87, 7.76 (2 m, 4H, Phth), 6.52 (d, 1H, J1,2 9.2 Hz, H-1),
5.89 (dd, 1H, J3,4 9.2 Hz, H-3), 5.22 (dd, 1H, J4,5 10.4 Hz, H-4), 4.48
1.9. 3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl chloride (9)
0
(dd, 1H, J2,3 10.8 Hz, H-2), 4.38 (dd, 1H, J6,6 12.4 Hz, H-6), 4.15
(dd, 1H, H-60), 4.03 (m, 1H, J5,6 4.4, J5,6 2.0 Hz, H-5), 2.12, 2.05,
Cl2HCOCH3 (0.97 mL, 10.9 mmol) and then BF3ꢁEt2O (0.62 mL,
5 mmol) were added to a solution of 5 (0.6 g, 1.25 mmol) in dry
CHCl3 (1.5 mL). After being stirred for 10 min under N2, the reac-
tion mixture was heated for 3 h at 65 °C. This was then diluted
with CHCl3 (50 mL), washed with H2O and satd aq NaHCO3, dried
over MgSO4, and concentrated to give crude 9 (0.52 g, 91%, white
power) of sufficient purity for use in the glycosylation reaction.
Recrystallization from diethyl ether/petroleum ether yielded 9
0
2.00, 1.87 (4 s, 12H, 4 ꢄ OAc); 13C NMR (400 MHz, CDCl3): d
170.87, 170.22, 169.67, 168.84, 167.56 (6 ꢄ C@O), 134.69, 123.98
(Phth), 89.91 (C-1), 72.77 (C-5), 70.65 (C-3), 68.12 (C-4), 61.68
(C-6), 53.64 (C-2), 20.95, 20.92, 20.79, 20.57 (4 ꢄ acetyl CH3); Anal.
Calcd for C22H23NO11: C, 55.35; H, 4.86; N, 2.93. Found: C, 55.51; H,
5.08; N, 2.89. The
a
anomer remained in the mixture (syrup): 1H
NMR (400 MHz, CDCl3): d 7.85, 7.75 (2 m, 4H, Phth), 6.57 (dd, 1H,
J3,4 9.2 Hz, H-3), 6.29 (d, 1H, J1,2 3.2 Hz, H-1), 5.17 (dd, 1H, J4,5
(0.45 g, 80%): mp 151–152 °C, lit.38 mp 148–151 °C; ½a 2D0
ꢃ
+61 (c
m 1751,
0
10.4 Hz, H-4), 4.72 (dd, 1H, J2,3 11.6 Hz, H-2), 4.37 (dd, 1H, J6,6
0.5, CHCl3), lit.38 +62 (c 1, CHCl3); Rf 0.57 (solvent D); IR:
12.4 Hz, H-6), 4.14 (dd, 1H, H-60), 3.86 (m, 1H, J5,6 3.6, J5,6 2.0 Hz,
1767 (acetyl C@O), 1714 cmꢂ1 (Phth C@O); 1H NMR (400 MHz,
CDCl3): d 7.89, 7.78 (2 m, 4H, Phth), 6.20 (d, 1H, J1,2 9.6 Hz, H-1),
5.80 (dd, 1H, J3,4 8.8 Hz, H-3), 5.25 (dd, 1H, J4,5 10.4 Hz, H-4), 4.53
0
H-5), 2.13, 2.09, 2.06, 1.88 (4 s, 12 H, 4 ꢄ OAc); 13C NMR
(100 MHz, CDCl3): d 170.94, 170.02, 169.79, 169.56 (6 ꢄ C@O),
134.68, 123.95 (Phth), 90.72 (C-1), 70.36 (C-5), 69.56 (C-4), 67.18
(C-3), 61.70 (C-6), 52.99 (C-2), 21.20, 20.95, 20.86 (4 ꢄ COCH3).
0
(dd, 1H, J2,3 10.4 Hz, H-2), 4.34 (dd, 1H, J6,6 12.4 Hz, H-6), 4.21
(dd, 1H, H-60), 3.98 (m, 1H, J5,6 4.8, J5,6 2.0 Hz, H-5), 2.14, 2.05,
0

D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
15
1.88 (3 s, 9H, 3 ꢄ OAc); 13C NMR (100 MHz, CDCl3): d 170.86,
170.19, 169.52 (5 ꢄ C@O), 134.79, 124.08 (Phth), 85.75 (C-1),
75.93 (C-5), 70.80 (C-3), 68.34 (C-4), 61.88 (C-6), 57.71 (C-2),
20.97, 20.79, 20.59 (3 ꢄ acetyl CH3); Anal. Calcd for C20H20NO9Cl:
C, 52.93; H, 4.44; N, 3.09. Found: C, 53.01; H, 4.29; N, 3.02.
(0.25 g, 0.97 mmol) were added and stirring was continued for
10 min. Then, a solution of 9 (0.25 g, 0.55 mmol) in CH2Cl2 (5 mL)
was dripped on to the reaction mixture. After stirring for 20 h at
rt, the mixture was diluted with CHCl3, filtered over the gel layer
(MN Kieselgel 60), and concentrated. The addition of MeOH caused
the precipitation of 13, which was filtered. The filtrate was chro-
matographed (solvent A) to yield an additional portion of 13 (to-
1.10. 3,4,6-Tri-O-acetyl-2-deoxy-2-(3,4,5,6-
tetrachlorophthalimido)-b-
D
-glucopyranosyl chloride (10)
tally 0.3 g, white solid, 99%): mp 193–196 °C; ½a D20
ꢂ22 (c 0.5,
ꢃ
CHCl3); Rf 0.59 (solvent E); IR:
m 2872–2950 (C–H), 1750 (acetyl
This was synthesized from 6 as previously reported.5
C@O), 1717 cmꢂ1 (Phth C@O); 1H NMR (400 MHz, CDCl3): d 7.86,
7.75 (2 m, 4H, Phth), 5.77 (dd, 1H, J3,4 9.2 Hz, H-3), 5.47 (d, 1H,
0
1.11. Diosgenyl 3,4,6-tri-O-acetyl-2-deoxy-2-
J1,2 8.4 Hz, H-1), 5.16 (dd, 1H, J4,5 10.0 Hz, H-4), 4.33 (dd, 1H, J6,6
trifluoroacetamido-b-
D
-glucopyranoside (11)
12.4 Hz, H-6), 4.30 (dd, 1H, J2,3 10.4 Hz, H-2), 4.15 (dd, 1H, H-60),
0
3.86 (m, 1H, J5,6 4.4, J5,6 2.4 Hz, H-5), 2.10, 2.03, 1.86 (3 s, 9H,
A mixture of diosgenin (0.18 g, 0.435 mmol) and 4 Å molecular
sieves (1.2 g) in anhyd CH2Cl2 and Et2O (21 mL, 8:13 v/v) was stir-
red at rt under N2 for 10 min. Next AgOTf (0.22 g, 0.86 mmol) was
added and stirring was continued for 10 min. Then, a solution of 7
(0.27 g, 0.65 mmol) in CH2Cl2 (7 mL) was allowed to drip on to the
reaction mixture. After stirring for 20 h at rt, the mixture was neu-
tralized with Et3N (0.4 mL, 2.9 mmol), diluted with CHCl3, filtered
over the gel layer (MN Kieselgel 60), and concentrated. The addi-
tion of MeOH precipitated 11 (0.24 g, powder, 69%); all analyses
are in agreement with those previously reported for the reaction
with bromide.5
3 ꢄ OAc); diosgenyl protons: 5.22 (m, C6-H), 4.38 (dd, C16-H),
3.46 (m, C26-He), 3.36 (t, C26-Ha), 2.06 (m, C4-2H), 0.95 (d, CH3),
0.88 (s, CH3), 0.78 (d, CH3), 0.74 (s, CH3); 13C NMR (100 MHz,
CDCl3): d 170.96, 170.43, 169.71 (5 ꢄ C@O), 134.51, 123.83 (Phth),
97.00 (C-1), 71.90 (C-5), 71.09 (C-3), 69.33 (C-4), 62.26 (C-6), 55.05
(C-2), 20.98, 20.87, 20.69 (3 ꢄ acetyl CH3); diosgenyl carbons:
140.41 (C-5), 122.04 (C-6), 109.48 (C-22), 81.98 (C-16), 79.63
(C-3), 67.04 (C-26), 62.40 (C-17), 56.63 (C-14), 50.17 (C-9), 41.79
(C-20), 40.43 (C-13), 39.90 (C-12), 38.76 (C-4), 37.27 (C-1), 36.93
(C-10), 32.20 (C-7), 32.01 (C-15), 31.57 (C-23), 31.54 (C-25), 30.48
(C-2), 29.52 (C-24), 28.99 (C-8), 21.02 (C-11), 19.50 (C-19), 17.34
(C-27), 16.44 (C-18), 14.71 (C-21); Anal. Calcd for C47H61NO12: C,
67.85; H, 7.39; N, 1.68. Found: C, 67.89; H, 7.42; N, 1.59.
1.12. Diosgenyl 3,4,6-tri-O-acetyl-2-deoxy-2-(2,2,2-
trichloroethoxycarbonylamino)-b-D-glucopyranoside (12)
1.14. Diosgenyl 3,4,6-tri-O-acetyl-2-deoxy-2-(3,4,5,6-
A mixture of diosgenin (0.148 g, 0.36 mmol) and 4 Å molecular
sieves (1.4 g) in anhyd CH2Cl2 and Et2O (16 mL, 3:5 v/v) was stirred
at rt under N2 for 10 min. Next, AgOTf (0.18 g, 0.72 mmol) was
added and stirring was continued for 10 min. Then, a solution of
8 (0.27 g, 0.54 mmol) in CH2Cl2 (8 mL) was allowed to drip on to
the reaction mixture. After stirring for 20 h at rt, the mixture was
neutralized with Et3N (0.4 mL, 2.9 mmol), diluted with CHCl3, fil-
tered over the gel layer (MN Kieselgel 60), and concentrated. The
addition of MeOH caused the precipitation of 12 (0.27 g, white
tetrachlorophthalimido)-b-D-glucopyranoside (14)
A mixture of diosgenin (0.094 g, 0.25 mmol) and 4 Å molecular
sieves (0.9 g) in anhyd CH2Cl2 (10 mL) was stirred at rt under N2 for
10 min. Next, s-collidine (0.12 mL, 0.91 mmol) and AgOTf (0.16 g,
0.61 mmol) were added and stirring was continued for 10 min.
Then a solution of 10 (0.20 g, 0.34 mmol) in CH2Cl2 (5 mL) was
dripped on to the reaction mixture. After stirring for 20 h at rt,
the mixture was diluted with CHCl3, filtered over the gel layer
(MN Kieselgel 60), and concentrated. The addition of MeOH caused
14 to precipitate (0.19 g, white solid, 87%); all analyses are in
agreement with previously reported for the reaction with
bromide.39
powder, 86%): mp >184 °C (dec); ½a D20
ꢂ53 (c 0.5, CHCl3); Rf 0.57
ꢃ
(solvent B); IR:
m 3301 (N–H), 2874–2950 (C–H), 1745 (acetyl
C@O), 1704 (Troc C@O), 1559 cmꢂ1 (–NH, C–N); 1H NMR
(400 MHz, CDCl3): d 5.37 (dd, 1H, J3,4 9.6 Hz, H-3), 5.20 (d, 1H,
NH), 5.05 (dd, 1H, J4,5 9.2 Hz, H-4), 4.81 (d, 1H, J1,2 8.0 Hz, H-1),
0
4.78 (d, 1H, Cl3CCH2), 4.68 (d, 1H, Cl3CCH2), 4.27 (dd, 1H, J6,6
1.15. Diosgenyl 2-deoxy-2-trifluoroacetamido-b-D-
glucopyranoside (15)
12.0 Hz, H-6), 4.10 (dd, 1H, H-60), 3.69 (m, 1H, J5,6 4.8 Hz, H-5),
3.50 (m, 1H, J2,3 10.4 Hz, H-2), 2.08, 2.04, 2.03 (3 s, 9H, 3 ꢄ OAc);
diosgenyl protons: 5.32 (m, C6-H), 4.41 (dd, C16-H), 3.50 (m, C26
-
This was synthesized from 11 as previously reported.5
He), 3.37 (t, C26-Ha), 2.24 (m, C4-2H), 0.99 (s, CH3), 0.97 (d, CH3),
0.79 (d, CH3), 0.78 (s, CH3); 13C NMR (100 MHz, CDCl3): d 170.95,
170.84, 169.75 (3 ꢄ ester C@O), 154.14 (amide C@O), 99.44 (C-1),
74.62 (Troc CH2), 71.85 (C-5 and C-3), 69.08 (C-4), 62.43 (C-6),
56.68 (C-2), 20.99, 20.90, 20.86 (3 ꢄ ester CH3); diosgenyl carbons:
140.32 (C-5), 122.23 (C-6), 109.51 (C-22), 81.02 (C-16), 80.08 (C-3),
67.06 (C-26), 62.28 (C-17), 56.84 (C-14), 50.25 (C-9), 41.81 (C-20),
40.47 (C-13), 39.96 (C-12), 38.96 (C-4), 37.33 (C-1), 37.05 (C-10),
32.26 (C-7), 32.04 (C-15), 28.99, 29.64, 30.50, 31.58 (C-8, C-24, C-
25, C-23, C-2,), 21.03 (C-11), 19.57 (C-19), 17.34 (C-27), 16.48 (C-
18), 14.72 (C-21); Anal. Calcd for C42H60NO12Cl3: C, 57.50; H,
6.89; N, 1.60. Found: C, 57.31; H, 6.97; N, 1.59.
1.16. Diosgenyl 2-deoxy-2-(2,2,2-
trichloroethoxycarbonylamino)-b-D-glucopyranoside (16)
Procedure f: Et3N (1.2 mL, 8.55 mmol) was added to a solution of
12 (0.3 g, 0.34 mmol) in MeOH (7 mL). The mixture was stirred at
rt for 20 h and then evaporated. The residue was purified by col-
umn chromatography (solvent F) to yield 16 (0.18 g, white powder,
69%): mp 205–207 °C ; ½a D20
ꢂ60 (c 0.5, 1:1 CHCl3:MeOH); Rf 0.58
ꢃ
(solvent G); IR:
m 3200–3550 (O–H and N–H), 2850–2951 (C–H),
1719 (Troc C@O), 1545 cmꢂ1 (–NH, C–N); 1H NMR (400 MHz,
DMSO-d6): d 7.49 (d, 1H, NH), 4.96 (m, 2H, 3-OH, 4-OH), 4.88,
4.68 (2 d, 2H, Cl3CCH2), 4.40 (m, 1H, 6-OH), 4.39 (d, 1H, J1,2
0
1.13. Diosgenyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-
D
-
8.0 Hz, H-1), 3.67 (dd, 1H, J6,6 11.2 Hz, H-6), 3.41 (m, 2H, H-4, H-
glucopyranoside (13)
60), 3.07 (m, 3H, H-2, H-3, H-5); diosgenyl protons: 5.28 (d, C6-
H), 4.28 (dd, C16-H), 3.42 (m, C26-He), 3.21 (t, C26-Ha), 2.33, 2.20
(m, C4-2H), 0.93 (s, CH3), 0.90 (d, CH3), 0.73 (s, 2 ꢄ CH3); 13C
NMR (100 MHz, DMSO-d6): d 154.24 (amide C@O), 99.19 (C-1),
76.90 (C-3), 73.69 (Troc CH2), 73.23 (C-4), 70.69 (C-5), 61.00
A mixture of diosgenin (0.15 g, 0.37 mmol) and 4 Å molecular
sieves (1 g) in anhyd CH2Cl2 (10 mL) was stirred at rt under N2
for 10 min. Next, s-collidine (0.19 mL, 1.44 mmol) and AgOTf

16
D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
Table 1
(C-6), 57.76 (C-2); diosgenyl carbons: 140.43 (C-5), 122.94 (C-6),
108.35 (C-22), 80.13 (C-16), 77.28 (C-3), 65.87 (C-26), 61.76 (C-
17), 55.68 (C-14), 49.48 (C-9), 41.04 (C-20), 40.14 (C-13), 38.88
(C-12), 38.34 (C-4), 36.68 (C-1), 36.31 (C-10), 31.49, 31.40, 30.93,
29.74, 29.11, 28.43 (C-2, C-7, C-8, C-15, C-23, C-24, C-25), 20.32
(C-11), 19.02 (C-19), 17.01 (C-27), 15.91 (C-18), 14.58 (C-21); Anal.
Calcd for C36H54NO9Cl3: C, 57.56; H, 7.25; N, 1.86. Found: C, 57.27;
H, 7.56; N, 1.84.
Procedure g: Compound 12 (0.2 g, 0.23 mmol) was added to a
solution of guanidine nitrate (0.12 g, 1 mmol) and MeONa
(0.2 mmol) in a mixture of MeOH and CH2Cl2 (5 mL; 9:1 v/v). The
mixture was stirred at rt for 1 h and then evaporated. The residue
was purified by column chromatography (solvent H) to give 16
(0.10 g, white powder, 57%).
Crystal data and structure refinement for 10
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
2 [C20 H16O9Cl5N]ꢁC7H7
1274.3
295(2)
1.54178
orthorhombic
C2221
10.818(2)
19.765(4)
25.910(5)
5540.0(2)
b (Å)
c (Å)
V (Å3)
Z
4
Dcalcd (Mg mꢂ3
)
1.528
5.232
2596
Absorption coefficient (mmꢂ1
F(000)
)
Crystal size (mm)
0.55 ꢄ 0.15 ꢄ 0.10
1.17. Diosgenyl 2-deoxy-2-phthalimido-b-D-glucopyranoside
H
Range for data collection (°)
3.41–67.72
(17)
Limiting indices
Reflections collected/unique
ꢂ11 6 h 6 11, ꢂ11 6 k 6 22, 0 6 l 6 30
4862/4640 [Rint = 0.0191]
96.5
Completeness 2H = 50.24° (%)
A 1 M solution of NaOMe in MeOH (1.4 mL) was added to a
solution of 13 (0.4 g, 0.48 mmol) in MeOH (80 mL). The mixture
was stirred at rt for 1 h and then neutralized with Dowex-50 W
(H+) ion-exchange resin, filtered, and the solvent was evaporated.
The yellow residue was purified by column chromatography (sol-
vent F) to give 17 (0.26 g, white powder, 76%): mp >271 °C (dec);
Refinement method
Full-matrix least-squares on F2
4640/0/357
Data/restraints/parameters
Goodness-of-fit on F2
1.117
R1 = 0.0484
wR2 = 0.1381
R1 = 0.0538
wR2 = 0.1437
0.003(2)
0.617 and ꢂ0.275
Final R indices [I >2
r(I)]
R Indices (all data)
½
a 2D0
ꢃ
ꢂ29 (c 0.5, 1:1 CHCl3:MeOH); Rf 0.60 (solvent G); IR:
m 3456
Absolute structure parameter
Largest diff. peak and hole (e Åꢂ3
(O–H), 2872–2949 (C–H), 1714 cmꢂ1 (Phth C@O); 1H NMR
(400 MHz, CDCl3): d 7.83, 7.71 (2 m, 4H, Phth), 5.33 (d, 1H, J1,2
8.4 Hz, H-1), 4.29 (dd, 1H, J3,4 8.4 Hz, H-3), 4.20 (m, 1H, 4-OH),
4.08 (dd, 1H, J2,3 10.8 Hz, H-2), 3.90 (m, 3H, H-6, H-60, 3-OH),
3.71 (dd, 1H, J4,5 9.2 Hz, H-4), 3.48 (m, 1H, H-5); diosgenyl pro-
tons: 5.21 (m, C6-H), 4.28 (dd, C16-H), 3.39 (m, C26-He), 3.36 (t,
)
1.20. Diosgenyl 2-amino-2-deoxy-b-D-glucopyranoside (18)
from 17
C
26-Ha), 2.03, 1.80 (2 m, C4-2H), 0.95 (d, CH3), 0.85 (s, CH3),
Ethylenediamine (1.08 mL, 16 mmol) was added to a solution of
17 (0.225 g, 0.32 mmol) in ethanol (3 mL). The mixture was stirred
at 60 °C for 2.5 h and evaporated. The yellow residue was purified
by column chromatography (solvent H containing 0.2% Et3N) to
give 18 (0.15 g, 81%); all data as reported for other procedures.5
0.78 (d, CH3), 0.74 (s, CH3); 13C NMR (100 MHz, CDCl3):
d
168.69 (2 ꢄ C@O), 134.36, 131.85, 123.73 (Phth), 97.16 (C-1),
75.59 (C-5), 71.96 (C-3), 71.83 (C-4), 62.11 (C-6), 57.07 (C-2);
diosgenyl carbons: 140.38 (C-5), 122.04 (C-6), 109.49 (C-22),
81.00 (C-16), 79.35 (C-3), 67.05 (C-26), 62.28 (C-17), 56.63 (C-
14), 50.17 (C-9), 41.80 (C-20), 40.44 (C-13), 39.92 (C-12), 38.78
(C-4), 37.27 (C-1), 36.90 (C-10), 32.20 (C-7), 32.01 (C-15), 31.57
(C-23), 31.55 (C-25), 30.49 (C-2), 29.60 (C-24), 29.00 (C-8),
20.98 (C-11), 19.48 (C-19), 17.33 (C-27), 16.44 (C-18), 14.72 (C-
21); MALDI-TOFMS: m/z 728.7 (M+Na)+; Anal. Calcd for
C41H55NO9 ꢄ 1.5 H2O: C, 67.19; H, 7.98; N, 1.91. Found: C,
67.61; H, 8.04; N, 1.84.
1.21. Diosgenyl 2-amino-2-deoxy-b-
D-glucopyranoside (18) and
diosgenyl 2-acetamido-2-deoxy-b-
D-glucopyranoside (19) from
14
These were synthesized as previously reported.5
1.22. Diosgenyl 2-amino-2-deoxy-b-D-glucopyranoside (18)
from 14
1.18. Diosgenyl 2-amino-2-deoxy-b-D-glucopyranoside (18)
from 15
An 85% solution of hydrazine hydrate (0.35 mL, 16 mmol) was
added to a solution of 14 (0.2 g, 0.21 mmol) in ethanol (4 mL).
The mixture was stirred at 80 °C for 24 h and evaporated. The res-
idue was purified using two procedures. One involved column
chromatography (solvent I containing 0.2% Et3N) and provided
pure 18 with a yield of 97% (0.12 g). The other involved dilution
of the crude residue in a mixture of CHCl3/MeOH (7:1, v/v), filtra-
tion over a layer of silica gel, evaporation, and crystallization from
methanol. This gave pure 18 (yield 74%) (0.09 g); all data as re-
ported for other procedures.5
An 0.1 M aq solution of NaOH (23 mL) was added to a solution
of 15 (0.32 g, 0.48 mmol) in acetone. The mixture was stirred at rt
for 3 h, neutralized with Dowex-50 W (H+) ion-exchange resin and
filtered, after which the solvent was azeotropically evaporated
with toluene and ethanol. The crude residue was purified by col-
umn chromatography (solvent H containing 0.2% Et3N) to give 18
(0.22 g, 80%); all data as reported for other procedures.5
1.19. Diosgenyl 2-amino-2-deoxy-b-D-glucopyranoside (18)
from 16
1.23. Description of the crystal structure of 10
Diffraction data were collected at room temperature (293 K) on
Zinc dust (0.8 g, 7.14 mmol) was added to a solution of 16
(0.22 g, 0.29 mmol) in glacial acetic acid (5 mL). The mixture was
stirred at rt for 2 h, diluted with toluene, and the zinc filtered off.
The filtrate was evaporated. The white residue was purified by col-
umn chromatography (solvent H) to give a chromatographically
homogeneous mixture of 18 and an unidentified product (0.18 g).
a
KUMA KM-4 four circle diffractometer40 Cu
Ka
radiation
(k = 1.54184 Å) using the 2H/x scan mode. Phase angles were ini-
tially determined with the SHELXS program.41 All H atoms bound to C
atoms were placed geometrically and refined using a riding model
with C–H = 0.96 Å and Uiso(H) = 1.2Ueq(C) (Uiso(H) = 1.5 Ueq(C) for

D. Bednarczyk et al. / Carbohydrate Research 367 (2013) 10–17
7. Yu, B.; Zhang, Y.; Tang, P. Eur. J. Org. Chem. 2007, 5145–5161.
17
the methyl H atoms). Table 1 summarizes the crystallographic
data, data collection, and structure refinement, Table S1 sets out
the coordinates of atoms and their isotropic temperature factors,
Table S2 lists a selection of the crystal’s important geometric
parameters, Table S3 summarizes the intra- and intermolecular
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2002, 50, 4310–4316.
short contacts and Table S4 shows the p–p interactions.
The crystal structure was refined to R1 = 0.0538 (4640 reflec-
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tions, all unique) and R1 = 0.0484 (4179 reflections with
F0 >2r(F0)) by the full-matrix least-squares method using the
SHELXL-97 program42 based on 120 parameters. Figure 2 illustrates
the compound’s structure, showing the conformation and atom
numbering system. Figure S1 shows the molecular packing in the
crystal. Figure S2 shows the p–p interactions in the crystal lattice.
All interactions demonstrated were found by the PLATON pro-
gram.43 The programs used to prepare the molecular graphics were
ORTEPII,44 PLUTO-78,45 and Mercury.46
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This research was financed by the European Union within the
European Regional Development Fund—grant UDA-POIG.01.01.
02-14-102/09-03 and by the Ministry of Science and Higher Educa-
tion—grant DS/530-8451-D193-12.
Supplementary data
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Full crystallographic details, excluding structures features, have
been deposited (Deposition No. CCDC 901908) with the Cambridge
Crystallographic Data Center. These data may be obtained, on re-
quest, from The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (tel.: +44 1223 336408; fax: +44 1223 336033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.carres.2012.
11.020.
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