Synthesis and characterisation of some new N-glycosides containing substituted pyridopyrimidinone, pyrimidopyridazinone, thiazolopyrimidinone and quinolizin-4-one moiety

Article abstract of DOI:10.3987/COM-08-11414

A series of new N-glycosides (D-glucosides, D-mannosides, L-and D-arabinosides, D-xylosides and one D-galactoside) containing heterocyclic moiety have been prepared by reaction of the corresponding heterocyclic amines with pyranoses in boiling methanol. The structures of the prepared compounds have been studied by means of proton and carbon NMR spectroscopy. In the most cases the products existed in DMSO solution as the single anomers. The Japan Institute of Heterocyclic Chemistry.

Full text of DOI:10.3987/COM-08-11414

HETEROCYCLES, Vol. 75, No. 10, 2008
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HETEROCYCLES, Vol. 75, No. 10, 2008, pp. 2477 - 2491. © The Japan Institute of Heterocyclic Chemistry
Received, 21st April, 2008, Accepted, 4th June, 2008, Published online, 9th June, 2008. COM-08-11414
SYNTHESIS AND CHARACTERISATION OF SOME NEW
N-GLYCOSIDES CONTAINING SUBSTITUTED
PYRIDOPYRIMIDINONE, PYRIMIDOPYRIDAZINONE,
THIAZOLOPYRIMIDINONE AND QUINOLIZIN-4-ONE MOIETY
Petr Šimůnek,*1 Jurij Svete,2 and Branko Stanovnik*2
1
University of Pardubice, Faculty of Chemical Technology, Department of
Organic Chemistry, Nám. Čs. Legií 565, CZ 532 10 Pardubice, Czech Republic
E-mail: petr.simunek@upce.cz
2
University of Ljubljana, Faculty of Chemistry and Chemical Technology,
Department of Organic Chemistry, Aškerčeva 5, SI 1000, Ljubljana, Slovenia
E-mail: branko.stanovnik@fkkt.uni-lj.si
Abstract – A series of new N-glycosides (D-glucosides, D-mannosides, L- and
D-arabinosides, D-xylosides and one D-galactoside) containing heterocyclic moiety
have been prepared by reaction of the corresponding heterocyclic amines with
pyranoses in boiling methanol. The structures of the prepared compounds have
been studied by means of proton and carbon NMR spectroscopy. In the most cases
the products existed in DMSO solution as the single anomers.
INTRODUCTION
N-Glycosides belong to the compounds with a wide range of biological activity.
Some N-glycosides derived from substituted and
quinazolines1
some
substituted
N-subst.phenyl-D-xylopyranosylamines2 show antineoplastic effects. On this account are interesting the
indigo N-glycosides (blue sugars)3, the analogues of naturally occuring akashins4 showing considerable
effect against various human cancer cells. Among other N-glycosidic indole derivatives with promising
cancerostatic effects belong staurosporine, K-252d, rebeccamycine and tjipanazoles.5–7 Antineoplastic
activity has also been described at some recently isolated N-glycosidic amides ansamytocines.8 Some
N-(β-D-glucopyranosyl)amides belong to the effective inhibitors of the glycogen phosphorylase.9
Oligosaccharidic N-glycosides have shown to be the convenient precursors for the synthesis of PBC
(polyhedral boron compounds) conjugates as the potential agents for BNCT (boron neutron capture

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HETEROCYCLES, Vol. 75, No. 10, 2008
therapy).10 Recently, a review article11 summarizing the synthesis, structure and evaluation of biological
activities of the N-glycosides containing quinazolinone skeleton has been published. The promising
potential of these compounds as cancerostatic and virostatic agents has been mentioned. Therefore, the
synthesis of new N-glycoside based compounds is an actual topic.
In this work we are dealing with the synthesis and characterisation of some new N-glycosides having
substituted pyridopyrimidinone, pyrimidopyridazinone, thiazolopyrimidinone and quinolizin-4-one
moiety.
RESULTS AND DISCUSSION
Aglycones
have
been
prepared
by
the
reaction
of
the
corresponding
2-amino-3-dimethylaminopropenoates with ambident nucleophiles according to the procedures described
in literature12–14 (Schemes 1 and 2).
Bredereck's
CbzHN
Me2N
O
CO2Me
reagent
SOCl2
MeOH
CbzHN
CO2Me
CbzHN
CO2H
toluene
reflux
1
2
Y
CbzHN
CO2Me
N
CbzHN
Y
AcOH
reflux
+
N
X
R
Me2N
Z
R
2
X = NH2, CH2CN, CH2CO2Et
Y = CH, N
R = H, Me
4a: R = H, Y = CH, Z = N
4b: R = Me, Y = CH, Z = N
4c: R = H, Y = N, Z = N
4d: R = H, Y = CH, Z = C-CN
4e: R = H, Y = CH, Z = C-CO2Et
O
O
Z
CbzHN
Y
H2N
Y
N
1. HBr/AcOH
2. NaHCO3
N
Z
R
R
4a-e
5a: R = H, Y = CH, Z = N
5b: R = Me, Y = CH, Z = N
5c: R = H, Y = N, Z = N
5d: R = H, Y = CH, Z = C-CN
5e: R = H, Y = CH, Z = C-CO2Et
Scheme 1. Preparation of the aglycones 5a-e

HETEROCYCLES, Vol. 75, No. 10, 2008
2479
CN
CN
Bredereck's
reagent
CO2Et
HN
CO2Et
NaOH
+
ClH.H2N
CO2Et
HN
CO2Et
CO2Et
toluene
reflux
CO2Et
EtOH
EtO
CN
NMe2
CO2Et
N
O
S
S
NH2
+
HN
CN
AcOH
reflux
N
CO2Et
CO2Et
N
H
N
CN
NMe2
N
O
N
S
S
N2H4 . H2O
N
CO2Et
N
ethanol
reflux
N
H
NH2
CN
O
3
Scheme 2. Preparation of the aglycone 3
After the protecting group removal the aglycones were subjected to the reaction with the corresponding
sugars in boiling methanol in the presence of acetic acid15 (Scheme 3). The structure of the prepared
N-glycosides has been studied by 1H and 13C NMR spectroscopy.
O
O
H
H2N
Y
sugar
sug
N
Y
N
N
MeOH/H+
reflux
Z
R
Z
R
5a-e
6a-o
6a: R = H, Y = CH, Z = N, sug = D-glucose
6b: R = H, Y = CH, Z = N, sug = L-arabinose
6c: R = H, Y = CH, Z = N, sug = D-arabinose
6d: R = H, Y = CH, Z = N, sug = D-xylose
6e: R = H, Y = CH, Z = N, sug = D-mannose
6f: R = Me, Y = CH, Z = N, sug = D-galactose
6g: R = Me, Y = CH, Z = N, sug = D-xylose
6h: R = H, Y = N, Z = N, sug = D-glucose
6i: R = H, Y =N, Z = N, sug = L-arabinose
6j: R = H, Y = N, Z = N, sug = D-mannose
6k: R = H, Y = CH, Z = C-CN, sug = D-glucose
6l: R = H, Y = CH, Z = C-CN, sug = D-arabinose
6m: R = H, Y = CH, Z = C-CO2Et, sug = D-xylose
6n: R = H, Y = CH, Z = C-CO2Et, sug = D-mannose
6o: R = H, Y = CH, Z = C-CO2Et, sug = L-arabinose
N
S
N
S
D-glucose
MeOH/H+
reflux
N
N
N
D-glucose
NH2
H
O
O
6p
3
Scheme 3. Preparation of the glycosides 6a-p

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HETEROCYCLES, Vol. 75, No. 10, 2008
In solution, the aldopyranoses can occur in the two anomeric forms, α and β. In addition to that, each
form can exist in two conformations, 4C1 and 1C4 (Scheme 4).
The abundance of the individual forms is affected by many factors as a solvent, type of the sugar,
substituents, temperature, etc. For the structural determination of the saccharidic part of the glycoside, the
chemical shift (δ) of the anomeric proton and the value of the vicinal coupling constant 3J(H1,H2) have been
used as the most important NMR parameters. The coupling constant value indicates the relative
orientation of the two protons according to the Karplus equation. The largest values are reached for the
diaxial configuration (7–8 Hz), smaller (~ 4 Hz) for the equatorial-axial arrangement and even smaller (<
2 Hz) for the axial-equatorial or the equatorial-equatorial oriented protons.16
1
The chemical shift of the anomeric protons has been assigned on the basis of 2D H–13C HMQC pulse
sequence by its correlation with the anomeric carbons signals having the characteristic chemical shift
(between 80–90 ppm).
O
O
O
O
4C1
1C4
Scheme 4.
Five glycosides existed in DMSO solution as a anomeric mixture (6a–d and 6i). Except 6d, the α anomer
predominated. The compounds 6e–h and 6j–p existed in DMSO solution as pure anomers. The
parameters relevant to the determination of the structure of the glycosidic part are shown in the Table 1.
D-Glucosides: The product 6a exists in DMSO solution as a mixture of anomers α and β in the rate of
1
11:1. Based on H–13C HMQC spectrum, this compound has the anomeric proton as dd with chemical
shift 4.97 ppm and coupling constants 4.5 and 1.5 Hz. The larger one corresponds rather to the eq-ax
arrangement. The structure of the glycosidic part corresponds then to the α-4C1(D) conformation. The
anomeric proton of the minor component is difficult to determine due to its low abundance. Probably it is
dd with δ 4.44 and coupling constant 6.5–7.5 Hz (difficult to decise due to the low abundance). These
data correspond to β-4C1(D). Compounds 6h, k and p exist in DMSO solution as the single anomers.
According to the δ and coupling constants (4.31–4.45 ppm, 6.5–7.6 Hz) the structure of the compounds is
β-4C1(D).
L-Arabinosides: for compounds 6b and i the structure α-4C1(L) predominates. The α/β ratios are in
DMSO solution 7:1 (6b) and 2:1 (6i). The minor component of 6i has anomeric proton with δ 5.06 (dd
with the coupling constants values 8.8 and 1.4 Hz). The larger one corresponds to the interaction with NH
1
proton (NH proton was identified by H–15N HMBC). The smaller one corresponds to the β-1C4(L). This

HETEROCYCLES, Vol. 75, No. 10, 2008
2481
is maybe also supported by the untypical chemical shift of the anomeric carbon of the minor form (78.7
1
1
ppm against 88.7 for β-4C1(L) 6b), as well as by J(13C, H) (156.8 Hz vs. 161.3 Hz at 6b). The minor
component of 6b is β-4C1(L), the coupling constant could not be read due to the signal overlap. The
anomeric configuration β is evidenced by the δ value 5.23–5.24. The product 6o exists in DMSO solution
as a single anomer. The comparison of the anomeric carbon chemical shift with 6b and 6i (83.6 vs. 83.8
resp. 83.5) gives α-4C1(L). Due to the signals overlap the value of the anomeric proton can be only
guessed by comparison with 6b and 6i as 4.67–4.69 ppm.
D-Arabinosides: 6c exists in DMSO solution as a mixture of α/β isomers in ratio 7:1. Based on the
coupling constant (7.3 Hz) it can be concluded on the ax-ax arrangement. It is possible only for α-1C4(D).
This structure is mentioned in literature17 to be more stable for D-arabinose. The minor component is
β-1C4(D), it is in accordance with the coupling constant 3.5 Hz, typical for the eq-ax arrangement. The
4
chemical shifts here show the opposite trend than in the conformations C1 (6a, d) where α resonates at
lower field than β. The product 6l exists in DMSO solution as a single anomer. Owing to the signals
overlap it was not possible to determine exactly neither the chemical shift nor the coupling constant value
of the anomeric proton. The approximate value of δ(1H) is 4.68. Based on the comparison of the carbon
parameters and the approximate δ(1H) with 6c it is possible to assume to the α-1C4(D) arrangement.
D-Xylosides: The major component of 6d is β-4C1(D) (4.5 ppm, 7.5 Hz typical for the ax-ax arrangement).
The minor one is then α-4C1(D) (5.03 ppm, 4.3 Hz). The anomeric ratio α/β is 1:4. The products 6g and
6m exist in DMSO solution as single anomers. According to the relevant NMR parameters (Table 1) both
the products have the structure β-4C1(D).
D-Mannosides: The products 6e, 6j and 6n are single anomers and have the arrangement α-1C4(D) (about
10 Hz, typical for the ax-ax arrangement, 4.95–4.98 ppm typical for the α anomer). It is in accordance
with literature17 stating that the D-mannose is more stable in the α configuration.
According to the δ and the coupling constant (4.38 ppm, 8.5 Hz) D-galactoside 6f has the arrangement
β-4C1(D). The product exists in DMSO solution as a single anomer.
EXPERIMENTAL
The NMR spectra were measured at laboratory temperature using Bruker AVANCE 500 spectrometer
operating at 500.13 MHz (1H),125.77 MHz (13C) and 50.69 MHz (15N) equipped with 5 mm broadband
probe with magnetic field gradients in the direction of the z axis and Bruker Avance DPX 300
spectrometer operating at 300.13 MHz (1H) and 75.48 MHz (13C). The proton NMR spectra were
calibrated on the central signal of the solvent multiplet (δ 2.55, DMSO-d6) and on TMS (δ 0.0, CDCl3).

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HETEROCYCLES, Vol. 75, No. 10, 2008
13
The C NMR spectra were calibrated on the central signal of the solvent multiplet (δ = 39.6 DMSO-d6
and 76.9 CDCl3).
The carbon NMR spectra were measured in the standard way and by the APT pulse sequence (spectral
width 26.455 kHz, acquisition time 1.238 s, zero filling to 64 k and line broadening 1 Hz prior to Fourier
transformation). 2D gs 1H–13C HMQC experiment was performed with the one bond CH coupling 145 Hz,
2k × 128 zero filled to 2k × 1k, sinebell squared in both dimensions and processed in magnitude mode. 1J
1
(13C, H) coupling constants were taken from the gated decoupled carbon spectra (spectral width 30.03
kHz, acquisition time 1.091 s, zero filling to 64k and line broadening 5 Hz prior to Fourier
transformation).
The pulse programs were taken from Bruker software library.
Table 1: Relevant NMR parameters of the glycosides 6a-p
Compound Sugar δ(H1)
3J (H1, H2)
δ(C1)
1J (C1,H1)
α/β
Structure
Hz
4.5
6.8–7.8
Hz
161.1
ratio
6a
6b
6c
6d
D-glu
L-ara
D-ara
4.97
4.44*
4.67
5.23
4.67
5.25
83.2
11:1
7:1
7:1
1:4
α-4C1(D)
β-4C1(D)
α-4C1(L)
β-4C1(L)
α-1C4(D)
β-1C4(D)
α-4C1(D)
β-4C1(D)
α-1C4(D)
β-4C1(D)
β-4C1(D)
β-4C1(D)
α-4C1(L)
β-1C4(L)
α-1C4(D)
β-4C1(D)
α-1C4(D)
β-4C1(D)
α-1C4(D)
α-4C1(L)
β-4C1(D)
7.5
83.8
88.7
83.9
88.7
81.4
85.5
80.5
86.0
85.6
84.8
83.5
78.7
80.3
84.8
83.5
85.9
80.9
83.6
85.6
154.8
161.3
155.4
162.1
159.7
153.8
151.4
**
7.3
3.5
4.3
7.2
10.3
8.5
7.1
D-xylo 5.03
4.50
D-man 4.98
D-gala 4.38
D-xylo 4.45
6e
6f
6g
6h
6i
D-glu
L-ara
4.47
4.66
5.06
7.2
151.0
152.8
156.8
151.9
151.6
153.9
152.5
6.5–7 **
1.4
2:1
6j
6k
6l
6m
6n
6o
6p
D-man 4.98
D-glu
D-ara
D-xylo 4.44
D-man 4.95
L-ara
D-glu
9.9
4.50
6.5
**
4.68**
6.9
9.9
**
4.68**
4.31
7.6
150.0
* Not possible to determine with certainty due to low abundance.
** Not possible to determine due to the signals overlap.
High resolution mass spectra were measured using AutoSpecQ spectrometer. The melting points were
measured on a Kofler hot stage microscope and were not corrected.

HETEROCYCLES, Vol. 75, No. 10, 2008
2483
Methyl N-benzyloxycarbonylglycinate (1): Thionyl chloride (10 mL) was added dropwise to a cooled
methanolic solution of N-benzyloxycarbonylglycine (20.9 g, 0.1 mol, 500 mL MeOH). Reaction mixture
was then stirred for additional 3 h at laboratory temperature. Volatile components were evaporated in
vacuo. The oily residue was dissolved in CH2Cl2 (120 mL) and shaken with 3% HCl (60 mL) and
saturated aqueous solution of NaHCO3 (60 mL). Organic phase was dried by anhydrous Na2SO4 and
evaporated in vacuo to give oily residue (1) in 94% yield.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 7.30–7.36 (m, 5H), 5.35 (br s, 1H), 5.12 (s, 2H), 3.97 (d, 2H, J
= 5.7 Hz), 3.74 (s, 3H).
Methyl (Z)-2-Benzyloxycarbonylamino-3-dimethylaminopropenoate (2): A mixture of (1) (14.87 g,
0.067 mol) and Bredereck’s reagent (17.9 mL, 0.086 mol) in dry toluene (50 mL) was heated in oil bath
to reflux for 2 h. Volatile components were evaporated in vacuo and solid product was washed by Et2O
(50 mL). Yield 82 %. Mp 108–109 °C, ref.14 gives mp 107–109 °C.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 7.25–7.33 (m, 5H), 5.53 (br s, 1H), 5.12 (s, 2H), 3.63 (s, 3H),
2.97 (s, 6H).
6-Amino-5H-thiazolo[3,2-a]pyrimidin-5-one (3): This compound was prepared by the same procedure
described in ref.13 (Scheme 2).
Reaction of (2) with nucleophiles
General procedure
Mixture of (2) (15 mmol) and corresponding nucleophile (15 mmol) in acetic acid (25 mL) was heated to
reflux for several hours. Mixture was then cooled and volatile components were evaporated in vacuo.
Solid residue was washed by Et2O and dried.
The following compounds were prepared in this manner:
3-[(Benzyloxycarbonyl)amino]-4H-pyrido[1,2-a]pyrimidin-4-one (4a): From 2-aminopyridine. Reflux
4.5 h. Yield 97 %. Mp 153–155 °C, ref.12 gives mp 146–148 °C.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 9.20 (br s, 1H), 8.88 (d, 1H, J = 7.2 Hz), 7.50–7.63 (m, 3H),
7.27–7.40 (m, 5H), 7.03–7.08 (m, 1H), 5.21 (s, 2H).
3-[(Benzyloxycarbonyl)amino]-8-methyl-4H-pyrido[1,2-a]pyrimidin-4-one
(4b):
From
2-amino-4-methylpyridine. Reflux 4 h. Yield 87 %. Mp 177–179 °C, ref.12 gives mp 178–179 °C.

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HETEROCYCLES, Vol. 75, No. 10, 2008
1H NMR (300.13 MHz, CDCl3): δ (ppm) 9.18 (s, 1H), 8.82 (d, 1H, J = 7.4 Hz), 7.33–7.44 (m, 7H), 6.94
(dd, 1H, J = 1.9, 7.4 Hz), 5.24 (s, 2H), 2.46 (s, 3H).
3-[(Benzyloxycarbonyl)amino]-4H-pyrimido[1,2-b]pyridazin-4-one (4c): From 3-aminopyridazine.
Reflux 6 h. Yield 93 %. Mp 185–186 °C, ref.12 gives mp 187–190 °C.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 9.17 (br s, 1H), 8.59 (dd, 1H, J = 1.5, 3.9 Hz), 7.84 (dd, 1H, J =
1.5, 9.0 Hz), 7.23–7.39 (m, 6H), 5.21 (s, 2H).
3-[(Benzyloxycarbonyl)amino]-1-cyano-4H-quinolizin-4-one (4d): From 2-pyridylacetonitrile. Reflux
4 h. Yield 87 %. Mp 211–212 °C, ref.14 gives mp 212–214 °C.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 9.05 (1H, ddd, J = 0.8, 1.3, 7.4 Hz), 8.77 (1H, s), 7.95 (1H,
ddd, J = 0.8, 1.4, 9.1 Hz), 7.82 (1H, s), 7.51 (1H, ddd, J = 1.3, 6.7, 9.1 Hz), 7.36–7.44 (5H, m), 7.15 (1H,
ddd, J = 1.4, 6.7, 7.4 Hz), 5.25 (2H, s).
3-[(Benzyloxycarbonyl)amino]-1-ethoxycarbonyl-4H-quinolizin-4-one
(4e):
From
ethyl
2-pyridylacetate. Reflux 6 h. Yield 68 %. Mp 178–180 °C, ref.14 gives mp 177–179 °C.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 9.23 (s, 1H), 9.21 (dd, 1H, J = 1.1, 9.4 Hz), 9.13 (dd, 1H, J =
1.1, 6.3 Hz), 7.79 (s, 1H), 7.47 (ddd, 1H, J = 1.1, 6.7, 9.4 Hz), 7.32–7.45 (m, 5H), 7.12 (ddd, 1H, J = 1.3,
6.3, 6.7 Hz), 5.27 (s, 2H), 4.40 (q, 2H, J = 7.1 Hz), 1.43 (t, 3H, J = 7.1 Hz).
Removing of the benzyloxycarbonyl protecting group
General procedure
A mixture of (4) and hydrobromic acid (33% solution in acetic acid, 2 mL per 1 mmol of 4) was heated in
water bath to 50–60 °C for 2 h. Mixture was cooled and resulting dihydrobromide was collected by
suction. Dihydrobromide was then treated with saturated aqueous solution of NaHCO3 until foaming was
over. Resulting solution was extracted several times by 100 mL of CH2Cl2. Extract was dried over
anhydrous Na2SO4 and solvent was evaporated in vacuo.
The following compounds were prepared in this way:
3-Amino-4H-pyrido[1,2-a]pyrimidin-4-one (5a): Yield 88 %. Mp 177–180 °C, ref.12 gives mp
176–178 °C.
1H NMR (300.13 MHz, DMSO-d6): δ (ppm) 8.72–8.75 (m, 1H), 7.90 (s, 1H), 7.42–7.45 (m, 2H),
7.07–7.12 (m, 1H), 5.18 (br s, 2H).

HETEROCYCLES, Vol. 75, No. 10, 2008
2485
3-Amino-8-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (5b): Yield 78 %. Mp 223–225 °C, ref.13 gives
mp 225–226 °C.
1H NMR (300.13 MHz, CDCl3): δ (ppm) 8.79 (d, 1H, J = 7.5 Hz), 7.97 (s, 1H), 7.28 (s, 1H), 6.83 (dd, 1H,
J = 1.8, 7.5 Hz), 3.92 (s, 2H), 2.41 (s, 3H).
3-Amino-4H-pyrimido[1,2-b]pyridazin-4-one (5c): Yield 31 %. Mp 251–253 °C, ref.12 gives mp
253–256 °C.
1H NMR (300.13 MHz, DMSO-d6): δ (ppm) 8.58 (dd, 1H, J = 1.8, 4.1 Hz), 7.81 (s, 1H), 7.77 (dd, 1H, J =
1.8, 9.3 Hz), 7.21 (dd, 1H, J = 4.2, 9.2 Hz), 5.60 (br s, 2H).
3-Amino-1-cyano-4H-quinolizin-4-one (5d): Yield 93 %. Mp 202–204 °C, ref.14 gives mp 204–205 °C.
1H NMR (DMSO-d6): δ (ppm) 8.82 (dd, 1H, J = 1.1, 7.5 Hz), 7.68 (dd, 1H, J = 1.5, 9.1 Hz), 7.38 (ddd,
1H, J = 1.1, 6.8, 9.1 Hz), 7.22 (s, 1H), 7.14 (ddd, 1H, J = 1.5, 6.8, 7.5 Hz), 5.64 (s, 2H).
3-Amino-1-ethoxycarbonyl-4H-quinolizin-4-one (5e): Yield 71 %. Mp 135–137 °C, ref.14 gives mp
136–139 °C.
1H NMR (DMSO-d6): δ (ppm) 8.91 (dd, 1H, J = 1.5, 7.2 Hz), 8.85 (dd, 1H, J = 1.5, 9.4 Hz), 7.74 (s,
1H), 7.35 (ddd, 1H, J = 1.2, 6.3, 9.3 Hz), 7.14 (ddd, 1H, J = 1.5, 6.4, 7.2 Hz), 5.41 (s, 2H), 4.31 (q, 2H, J
= 7.2 Hz), 1.34 (t, 3H, J = 7.2 Hz).
General procedure for synthesis of N-glycosides (ref.15)
A mixture of appropriate heterocyclic amine 5 (1.5 mmol) and sugar (1.5 mmol) was refluxed in
MeOH (6 mL) in the presence of acetic acid (0.3 mL) for 2 h. Mixture was then cooled and precipitated
product was collected by suction and dried on air.
Following compounds were prepared in this way:
3-[N-(D)-Glucopyranosyl]amino-4H-pyrido[1,2-a]pyrimidin-4-one (6a): Yield: 62 %. Mp 200–204 °C.
HREIMS: 323.112560 (C14H17N3O6, [M]+), calc. 323.111736.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.79–8.81 (m, α + β), 8.24 (s, 1H, α), 8.01 (s, 1H, β),
7.56–7.60 (m, α + β), 7.20–7.23 (m, α + β), 5.82 (d, 1H, J = 6.1 Hz, β), 5.79 (s, 1H, β), 5.66 (d, 1H, J =
4.0 Hz, α), 5.43 (d, 1H, J = 1.5 Hz, α), 5.30 (d, 1H, J = 4.4 Hz, β), 5.08 (d, 1H, J = 4.5 Hz, α), 5.00 (d, 1H,
J = 5.3 Hz, β), 4.97 (dd, 1H, anomeric, J = 1.5, 4.5 Hz, α), 4.94 (d, 1H, J = 6.0 Hz, α), 4.55 (d, 1H, J = 5.5
Hz, β), 4.52 (t, 1H, J = 5.6 Hz, α), 4.43–4.46 (m, 1H, β), 3.74–3.78 (m, 1H, β), 3.66–3.70 (m, 1H, α),
3.47–3.59 (m, β + α), 3.22 (d, 2H, J = 5.3 Hz, β), 3.15–3.20 (m, 1H, α). 13C NMR (125.77 MHz,

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HETEROCYCLES, Vol. 75, No. 10, 2008
DMSO-d6): δ (ppm) (α-anomer) 152.9, 142.6, 132.1, 130.9, 127. 8, 126.2, 125.4, 115.6, 83.2 (anomeric,
1J(13C, 1H) = 161.1 Hz), 74.0, 72.3, 70.8, 70.5, 61.2.
3-[N-(L)-Arabinopyranosyl]amino-4H-pyrido[1,2-a]pyrimidin-4-one (6b): Yield: 66 %. Mp
186–189 °C. HREIMS: 293.101850 (C13H15N3O5, [M]+), calc. 293.101171.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.79 (d, α + β, J = 7.0 Hz), 8.04 (s, 1H, β), 7.95 (s, 1H, α),
7.52–7.56 (m, α + β), 7.16–7.21 (m, α + β), 6.15 (d, 1H, α, J = 8.0 Hz), 6.00 (d, 1H, β, J = 10 Hz),
5.46–5.48 (m, 2H, β), 5.23–5.24 (m, α + β, anomeric β), 5.11 (d, 1H, α, J = 4.5 Hz), 4.83 (t, 1H, β, J = 5.5
Hz), 4.67 (dd, 1H, α, anomeric, J = 6.0, 7.5 Hz), 4.64 (d, 1H, α, J = 5.5 Hz), 4.12–4.14 (m, β, 1H),
3.91–3.94 (m, β, 1H), 3.81–3.84 (m, α + β), 3.73–3.77 (m, α + β), 3.64–3.68 (m, α + β), 3.51–3.54 (m, α +
13
β). C NMR (125.77 MHz, DMSO-d6): δ (ppm) (α anomer) 152.6, 142.1, 130.8, 130.4, 126.7, 126.1,
1
1
125.2, 115.4, 83.8 (anomeric, J(13C, H) = 154.8 Hz), 72.3, 70.0, 66.6, 63.7; (β anomer) 152.8, 142.3,
131.3, 130.5, 126.8, 126.1, 125.3, 115.4, 88.7 (anomeric, 1J(13C, 1H) = 161.3 Hz), 84.2, 80.2, 76.5, 61.8.
3-[N-(D)-Arabinopyranosyl]amino-4H-pyrido[1,2-a]pyrimidin-4-one (6c): Yield: 70 %. Mp
185–190 °C. HRESIMS: 294.1085 (C13H16N5O, [M+H]+), calc. 294.1090.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.78 (d, α + β, J = 7.5 Hz), 8.04 (s, 1H, β), 7.95 (s, 1H, α),
7.51–7.55 (m, α + β), 7.16–7.19 (m, α + β), 6.14 (d, 1H, α, J = 8.0 Hz), 5.99 (d, 1H, β, J = 10.0 Hz),
5.46–5.48 (m, 2H, β), 5.25 (d, 1H, anomeric β, J = 3.5 Hz), 5.23 (d, 1H, α, J = 5.0 Hz), 5.10 (d, 1H, J =
4.5 Hz), 4.83 (t, 1H, β, J = 5.5 Hz), 4.67 (dd, 1H, anomeric α, J = 6.5, 7.3 Hz), 4.64 (d, 1H, α, J = 5.0 Hz),
4.12–4.15 (m, 1H, β), 3.92–3.94 (m, 1H, β), 3.80–3.85 (m, α + β), 3.74–3.78 (m, α + β), 3.64–3.69 (m, 2H,
13
α), 3.51–3.54 (m, α + β). C NMR (125.77 MHz, DMSO-d6): δ (ppm) (α anomer) 152.6, 142.1, 130.8,
1
1
130.4, 126.8, 126.1, 125.2, 115.4, 83.9 (anomeric J(13C, H) = 155.4 Hz), 72.4, 70.0, 66.7, 63.7; (β
anomer) 152.8, 142.3, 131.4, 130.5, 126.8, 126.1, 125.3, 115.4, 88.7 (anomeric, 1J(13C, 1H) = 162.1 Hz),
84.2, 80.2, 76.6, 61.8.
3-[N-(D)-Xylopyranosyl]amino-4H-pyrido[1,2-a]pyrimidin-4-one (6d): Yield: 75 %. Mp
171.5–178 °C. HRESIMS: 294.1078 (C13H16N3O5, [M+H]+), calc. 294.1090.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.78–8.79 (m, α + β), 8.03 (s, 1H, α), 7.95 (s, 1H, β),
7.52–7.57 (m, α + β), 7.16–7.21 (m, α + β), 5.87 (d, 1H, β, NH, J = 6.9 Hz), 5.50 (d, 1H, α, NH, J = 5.5
Hz), 5.46 (d, α, J = 5.5 Hz), 5.30–5.32 (m, α + β), 5.20 (d, 1H, β, J = 2.7 Hz), 5.10 (d, β + α, J = 4.4 Hz),
5.03 (t, 1H, anomeric α, J = 4.3 Hz), 4.50 (t, 1H, anomeric β, J = 7.2 Hz), 4.04–4.12 (m, 1H, α), 3.76 (dd,
1H, β, J = 4.9, 11.0 Hz), 3.67 (dd, 1H, α, J = 4.0, 11.2 Hz), 3.58–3.64 (m, 2H, α), 3.40–3.45 (m, 1H β),
3.32–3.37 (m, 3H, β). 13C NMR (125.77 MHz, DMSO-d6): δ (ppm) (β-anomer) 152.6, 142.4, 131.0, 130.6,

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1
1
127.2, 126.2, 125.4, 115.5, 85.5 (anomeric J(13C, H) = 153.8 Hz), 77.0, 72.6, 69.9, 66.3; (α-anomer)
152.9, 142.6, 131.5, 130.9, 127.0, 126.2, 125.4, 115.6, 81.4 (anomeric, 1J(13C, 1H) = 159.7 Hz), 72.2, 70.7,
69.3, 63.0.
3-[N-(D)-Mannopyranosyl]amino-4H-pyrido[1,2-a]pyrimidin-4-one (6e): Yield: quantitative. Mp
+
179–189 °C. HRESIMS: 324.1187 (C16H18N3O6 , [M+H]+), calc. 324.1196.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.79 (d, 1H, J = 7.3 Hz), 8.01 (s, 1H), 7.55–7.56 (m, 2H),
7.18–7.21 (m, 1H), 5.69 (d, 1H, J = 10.4 Hz), 5.23 (br s, 1H), 4.98 (d, 1H, anomeric, J = 10.3 Hz), 4.83
(br s, 2H), 4.43 (br s, 1H), 3.85 (s, 1H), 3.72 (d, 1H, J = 11.7 Hz), 3.45–3.50 (m, 2H coincidence with the
water signal), 3.26–3.30 (m, 2H). 13C NMR (125.77 MHz, DMSO-d6): δ (ppm) 152.8, 142.3, 131.8,
130.8, 126.3, 126.1, 125.4, 115.7, 80.5 (anomeric, 1J(13C, 1H) = 151.4 Hz), 78.1, 74.5, 70.9, 67.3, 61.4.
3-[N-(D)-Galactopyranosyl]amino-8-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (6f): Yield 77 %. Mp
197–198 °C. HRESIMS: 338.1360 (C15H20N3O6 [M+H]+, calc. 338.1352.
1H NMR (300.13 MHz, DMSO-d6): δ (ppm) 8.74 (d, 1H, J = 7.5 Hz), 7.98 (s, 1H), 7.37 (br s, 1H), 7.07
(dd, 1H, J = 1.8, 7.5 Hz), 5.64 (d, 1H, J = 6.0 Hz), 5.14 (d, 1H, J = 5.5 Hz), 4.81 (d, 1H, J = 5.6 Hz),
4.62–4.65 (m, 1H), 4.42 (d, 1H, J = 4.8 Hz), 4.38 (dd, 1H, anomeric, J = 6.1, 8.5 Hz), 3.75–3.78 (m, 1H),
13
3.50–3.67 (m, 4H), 3.44–3.48 (m, 1H), 2.42 (s, 3H). C NMR (75.48 MHz, DMSO-d6): δ (ppm) 152.6,
142.5, 141.4, 131.7, 126.7, 124.7, 123.7, 118.1, 86.0 (anomeric), 76.1, 73.9, 69.9, 68.7, 60.7, 20.5.
3-[N-(D)-Xylopyranosyl]amino-8-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (6g): Yield 76 %. Mp
189–191 °C. HRESIMS 308.1256 (C14H18N3O5 [M+H]+), calc. 308.1246.
1H NMR (300.13 MHz, DMSO-d6): δ (ppm) 8.73 (d, 1H, J = 7.5 Hz), 7.91 (s, 1H), 7.38 (br s, 1H), 7.07
(dd, 1H, J = 1.9, 7.5 Hz), 5.72 (d, 1H, J = 6.8 Hz), 5.25 (d, 1H, J = 5.2 Hz), 5.12 (d, 1H, J = 4.0 Hz), 5.03
(d, 1H, J = 4.7 Hz), 4.45 (t, 1H, anomeric, J = 7.1 Hz), 3.74 (dd, 1H, J = 4.3, 6.1 Hz), 3.27–3.34 (m, 4H),
13
2.42 (s, 3H). C NMR (75.5 MHz, DMSO-d6): δ (ppm) 152.6, 142.6, 141.6, 131.5, 126.4, 124.7, 123.7,
118.1, 85.6 (anomeric), 76.9, 72.6, 69.9, 66.2, 20.5.
3-[N-(D)-Glucopyranosyl]amino-4H-pyrimido[1,2-a]pyridazin-4-one (6h): Yield: 55.5 %. Mp
214–221 °C. HRESIMS: 325.1140 (C13H17N4O6, [M+H]+), calc. 325.1148.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.68 (dd, 1H, J = 1.4, 3.9 Hz), 7.89 (s, 1H), 7.87 (dd, 1H, J
= 1.4, 9.2 Hz), 7.36 (dd, 1H, J = 4.0, 9.2 Hz), 6.19 (d, 1H, J = 6.1 Hz), 5.34 (d, 1H, J = 4.6 Hz), 5.14 (d,
1H, J = 2.9 Hz), 5.06 (d, 1H, J = 5.3 Hz), 4.59 (t, 1H, J = 5.7 Hz), 4.47 (t, 1H, anomeric, J = 7.2 Hz),
13
3.74–3.77 (m, 1H), 3.46–3.51 (m, 1H), 3.32–3.40 (m, 3H), 3.17–3.21 (m, 1H). C NMR (125.77 MHz,

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1
1
DMSO-d6): δ (ppm) 153.4, 146.6, 139.3, 134.7, 131.6, 128.5, 122.0, 84.8 (anomeric J(13C, H) = 151.0
Hz), 77.9, 77.3, 72.7, 70.4, 61.1.
3-[N-(L)-Arabinopyranosyl]amino-4H-pyrimido[1,2-a]pyridazin-4-one (6i): Yield: 68 %. Mp
196–202 °C. HRESIMS: 295.1055 (C12H15N4O5, [M+H]+), calc. 295.1042.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.67–8.69 (m, α + β), 7.83–7.90 (m, α + β), 7.33–7.38 (m, α
+ β), 6.47 (d, 1H, NH α, J = 7.9 Hz), 5.86 (d, 1H, NH β, J = 8.9 Hz), 5.67 (d, 1H, β, J = 5.0 Hz), 5.29 (br
s, 1H, α), 5.19 (br s, 1H, α), 5.06 (dd, 1H anomeric, β, J = 1.4, 8.8 Hz), 5.03 (br s, 1H, β), 4.66–4.68 (m,
anomeric, α, J = 6.5–7 Hz impossible to determine extactly due to signal overlap), 3.81–3.85 (m, α + β),
3.76–3.77 (m, α + β), 3.63–3.68 (m, α + β), 3.51–3.55 (m, α + β). 13C NMR (125.77 MHz, DMSO-d6): δ
1
1
(ppm) (α-anomer) 153.5, 146.5, 139.2, 134.7, 131.0, 128.1, 121.9, 83.5 (anomeric, J(13C, H) = 152.8
Hz), 72.3, 69.9, 64.6, 63.6; (β-anomer) 153.7, 146.6, 139.5, 134.7, 130.8, 128.8, 122.2, 78.7 (anomeric
1J(13C, 1H) = 156.8 Hz), 70.5, 70.3, 66.7, 63.9.
3-[N-(D)-Mannopyranosyl]amino-4H-pyrimido[1,2-a]pyridazin-4-one (6j): Yield: 74 %. Mp
210–217 °C. HRESIMS: 347.0981 (C13H16N4O6Na+, [M+Na]+), calc. 347.0968.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.67–8.68 (m, 1H), 7.89 (s, 1H), 7.85 (dd, 1H, J = 1.5, 9.2
Hz), 7.35 (dd, 1H, J = 4.0, 9.2 Hz), 5.96 (d, 1H, J = 9.9 Hz), 5.32 (br s, 1H), 4.98 (d, 1H, anomeric, J =
9.9 Hz), 4.89 (br s, 2H), 4.50 (br s, 1H), 3.86 (s, 1H), 3.74 (d, 1H, J = 11.3 Hz), 3.42–3.51 (m, 2H),
3.28–3.32 (m, 1H). 13C NMR (125.77 MHz, DMSO-d6): δ (ppm) 153.5, 146.6, 139.3, 134.6, 130.5,
128.9, 122.2, 80.3 (anomeric, 1J (13C, 1H) = 151.9 Hz), 78.2, 74.4, 70.7, 67.2, 61.4.
3-[N-(D)-Glucopyranosyl]amino-1-cyano-4H-quinolizin-4-one (6k): Yield 77 %. Mp 197–199 °C.
+
HREIMS: 347.112210 (C16H17N3O6 , [M]+), calc. 347.111736.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.91 (d, 1H, J = 7.3 Hz), 7.78 (d, 1H, J = 9.0 Hz), 7.50–7.53
(m, 1H), 7.40 (s, 1H), 7.25 (t, 1H, J = 6.9 Hz), 6.21 (d, 1H, J = 6.1 Hz), 5.32 (d, 1H, J = 4.4 Hz), 5.11 (d,
1H, J = 3.5 Hz), 5.04 (d, 1H, J = 5.3 Hz), 4.58 (t, 1H, J = 5.6 Hz), 4.50 (t, 1H, anomeric, J = 6.5 Hz),
13
3.74–3.78 (m, 1H), 3.46–3.51 (m, 1H), 3.42–3.45 (m, 1H), 3.30–3.36 (m, 2H), 3.15–3.20 (m, 1H). C
NMR (125.77 MHz, DMSO-d6): 152.4, 136.8, 130.6, 128.8, 126.2, 122.7, 118.0, 116.5, 113.6, 84.8
(anomeric, 1J (13C, 1H) = 151.6 Hz), 84.6, 77.7, 77.2, 72.8, 70.4, 61.1.
3-[N-(D)-Arabinopyranosyl]amino-1-cyano-4H-quinolizin-4-one (6l): Yield: 70 %. Mp 180–182 °C.
HREIMS: 317.101850 (C15H15N3O5, [M]+), calc. 317.101171.

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2489
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.89 (d, 1H, J = 7.4 Hz), 7.77 (d, 1H, J = 9.0 Hz),
7.49–7.52 (m, 1H), 7.35 (s, 1H), 7.23 (t, 1H, J = 7.3 Hz), 6.54 (d, 1H, J = 7.6 Hz), 5.27 (d, 1H, J = 5.1
Hz), 5.15 (d, 1H, J = 4.7 Hz), 4.67–4.70 (m, 2H, including anomeric), 3.80 (br s, 1H), 3.72–3.76 (m, 1H),
3.63–3.66 (m, 2H), 3.56 (d, 1H, J = 10.5 Hz). 13C NMR (125.77 MHz, DMSO-d6): δ (ppm) 152.4, 136.6,
130.0, 128.7, 126.2, 122.7, 117.9, 116.5, 113.1, 84.4, 83.5 (anomeric, 1J(13C, 1H) = 153.9 Hz), 72.4, 69.8,
66.7, 63.9.
3-[N-(D)-Xylopyranosyl]amino-1-ethoxycarbonyl-4H-quinolizin-4-one (6m): Yield 63 %. Mp
+
179–181 °C. HREIMS: 364.127850 (C17H20N2O7 , [M]+), calc. 364.127051.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.99 (d, 1H, J = 7.4 Hz), 8.92 (d, 1H, J = 9.4 Hz), 7.71 (s,
1H), 7.47–7.50 (m, 1H), 7.23 (t, 1H, J = 7.4 Hz), 6.12 (d, 1H, J = 6.4 Hz), 5.33 (d, 1H, J = 5.2 Hz), 5.21
(d, 1H, J = 3.9 Hz), 5.10 (d, 1H, J = 5.1 Hz), 4.44 (t, 1H, anomeric, J = 6.9 Hz), 4.36 (q, 2H, J = 7.1 Hz),
3.81 (dd, 1H, J = 5.0, 11.0 Hz), 3.38–3.45 (m, 1H, coincidence with water signal), 3.33–3.37 (m, 2H),
13
3.29 (t, 1H, J = 10.7 Hz), 1.40 (t, 3H, J = 7.1 Hz). C NMR (125.77 MHz, DMSO-d6): δ (ppm) 165.1,
1
1
152.8, 135.5, 128.9, 128.1, 126.1, 123.2, 116.1, 114.7, 102.2, 85.9 (anomeric, J(13C, H) = 152.5 Hz),
76.8, 72.3, 69.9, 66.2, 60.6, 14.2.
3-[N-(D)-Mannopyranosyl]amino-1-ethoxycarbonyl-4H-quinolizin-4-one (6n): Yield 86 %. Mp
180–181 °C. HREIMS: 417.1275 (C18H22N2O8Na [M+Na]+, calc. 417.1274.
1H NMR (300.13 MHz, DMSO-d6): δ (ppm) 8.99–9.01 (m, 1H), 8.92–8.95 (m, 1H), 7.77 (s, 1H), 7.49
(ddd, 1H, J = 1.3, 6.5, 9.4 Hz), 7.21–7.26 (m, 1H), 6.00 (d, 1H, J = 9.8 Hz), 5.21 (d, 1H, J = 5.3 Hz), 4.95
(d, 1H, J = 9.9 Hz, anomeric), 4.81 (dd, 2H, J = 5.4, 11.5 Hz), 4.30–4.42 (m, 3H), 3.84–3.87 (m, 1H),
3.70 (ddd, 1H, J = 2.1, 5.6, 11.6 Hz), 3.43–3.56 (m, 3H), 3.21–3.26 (m, 1H), 1.39 (t, 3H, J = 7.2 Hz). 13C
NMR (75.48 MHz, DMSO-d6): δ (ppm) 165.1, 152.8, 135.3, 128.0, 127.9, 126.0, 123.2, 116.1, 115.2,
102.4, 80.9 (anomeric), 78.3, 74.3, 70.8, 67.1, 61.1, 60.5, 14.2.
3-[N-(L)-Arabinopyranosyl]amino-1-ethoxycarbonyl-4H-quinolizin-4-one (6o): Yield 80.3 %. Mp
168–170 °C. HRESIMS: 387.1150 (C17H20N2O7Na+, [M+Na]+), calc. 387.1168.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.98 (d, 1H, J = 7.4 Hz), 8.93 (d, 1H, J = 9.4 Hz), 7.70 (s,
1H), 7.46–7.50 (m, 1H), 7.23 (t, 1H, J = 7.4 Hz), 6.50 (d, 1H, J = 7.8 Hz), 5.30 (br s, 1H), 5.24 (br s, 1H),
4.67–4.69 (m, 2H, including anomeric), 4.37 (q, 2H, J = 7.1 Hz), 3.82 (br s, 1H), 3.76–3.77 (m, 1H),
3.70–3.71 (m, 1H), 3.64–3.67 (m, 1H), 3.47 (dd, 1H, J = 2.8, 11.4 Hz), 1.39 (t, 3H, J = 7.1 Hz). 13C NMR
(125.77 MHz, DMSO-d6): δ (ppm) 165.2, 152.9, 135.3, 128.5, 127.9, 126.0, 123.2, 116.1, 114.2, 102.2,
83.6 (anomeric), 72.00, 70.0, 66.2, 62.8, 60.6, 14.3.

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6-[N-(D)-Glucopyranosyl]amino-5H-thiazolo[3,2-a]pyrimidin-5-one (6p): Yield: 89 %. Mp
193–198 °C. HREIMS: 329.068850 (C12H15N3O6S, [M]+), calc. 329.068157.
1H NMR (500.13 MHz, DMSO-d6): δ (ppm) 8.00 (d, 1H, J = 4.9 Hz), 7.62 (s, 1H), 7.52 (d, 1H, J = 4.9
Hz), 5.60 (d, 1H, J = 5.7 Hz), 5.30 (d, 1H, J = 5.0 Hz), 5.10 (d, 1H, J = 4.0 Hz), 5.02 (d, 1H, J = 5.3 Hz),
4.57 (t, 1H, J = 5.7 Hz), 4.31 (t, 1H, anomeric, J = 6.0, 7.6 Hz), 3.72–3.75 (m, 1H), 3.25–3.34 (m, 4H),
3.15–3.18 (m, 1H). 13C NMR (125.77 MHz, DMSO-d6): δ (ppm) 154.2, 150.1, 129.1, 128.1, 120.9, 113.9,
85.6 (anomeric, 1J (13C, 1H) = 150.0 Hz), 77.8, 77.3, 72.8, 70.5, 61.1.
ACKNOWLEDGEMENTS
P.Š. is indebted to the Ministry of Education, Youth and Sports of the Czech Republic for the finantial
support (Project No. MSM 002 162 7501).
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