Fast and efficient microwave synthetic methods for some new 2(1H)-pyridone arabinosides

Article abstract of DOI:10.1515/hc-2012-0091

Two series of novel 3-cyano-2-(2'' ,3'' ,4'' -tri- O - acetyl- β - d -arabinopyranosyloxy)pyridones 5a - h and 9a,b were synthesized. Microwave irradiation has been used to obtain these products in high yield under milder conditions by the reaction of 2(1 H )-pyridone or its salt with an activated arabinose. The silyl method was used to obtain the same nucleosides 5a - h and 9a,b . Triethylamine was used to remove the acetyl protecting groups from the sugar moiety and to produce the free nucleosides 6a - h and 10a,b in 85 - 91% yield.

Full text of DOI:10.1515/hc-2012-0091

DOI 10.1515/hc-2012-0091ꢀ
ꢀHeterocycl. Commun. 2012; 18(3): 135–141
Ibrahim M. Abdou*, Nora M. Rateb and Hany A. Eldeab
Fast and efficient microwave synthetic methods
for some new 2(1H)-pyridone arabinosides
Abstract: Two series of novel 3-cyano-2-(2″,3″,4″-tri-O- the deletion or change in the nature of the functional
acetyl-β-d-arabinopyranosyloxy)pyridones 5a–h and groups present on the heterocyclic base or their sugar
9a,b were synthesized. Microwave irradiation has been moieties (Al-Neyadi et al., 2011; Shen et al., 2012; Sun et
used to obtain these products in high yield under milder al., 2012). Varying sugar moieties from d-ribose present in
conditions by the reaction of 2(1H)-pyridone or its salt DNA strands to another pentose or hexose have produced
with an activated arabinose. The silyl method was used modified nucleosides with altered physical and chemi-
to obtain the same nucleosides 5a–h and 9a,b. Triethyl- cal properties. d-Arabinose has been found in the cell
amine was used to remove the acetyl protecting groups wall of mycobacterial species (Briken et al., 2004), and
from the sugar moiety and to produce the free nucleosides some analogs are the point of attachment of mycolic acids
6a–h and 10a,b in 85–91% yield.
(Brennan and Nikaido, 1995) but a few research groups are
interested in using d-arabinose as key starting materials
Keywords: microwave; 2-pyridone arabinosides; synthesis. for nucleoside synthesis (Andrzejewska et al., 2002).
Recent reports from our laboratory have described the
synthesis of novel pyridine and pyrimidine nucleosides
*Corresponding author: Ibrahim M. Abdou, Faculty of Science,
with significant biological and medicinal applications
Department of Chemistry, UAE University, Al-Ain, United Arab
(El-Sayed et al., 2009; Al-Neyadi et al., 2011). d-Arabinose
has been the key component for the synthesis of targeted
nucleosides. We report here new efficient and convenient
ecological methods for the synthesis of a series of novel
2-(β-d-arabinopyranosyloxy)pyridine derivatives 5, 6, 9
and 10.
Emirates, e-mail: i.abdou@uaeu.ac.ae
Nora M. Rateb: Faculty of Science, Department of Chemistry,
Cairo University, Giza, Egypt
Hany A. Eldeab: Faculty of Science, Department of Chemistry,
UAE University, Al-Ain, United Arab Emirates
Introduction
There is great interest in the development of new nucleo-
Results and discussion
side analogs of nucleic acids (Damia and D’Incalci, A variety of different modified nucleoside derivatives have
2009; De Clercq, 2012; Kale et al., 2012). Some nucleoside been previously synthesizedusing the classical approaches
analogs have been used in preclinical studies for several in solution, which are expensive and time-consuming. In
therapeutic indications including anticancer activity (Shi this report we describe new simple, efficient procedures
and Schinazi, 2001; Kawashima et al., 2011; Chen et al., for the synthesis of the target nucleosides 5a–h and 9a,b.
2012; Van Poecke et al., 2012).
Four different synthetic strategies to build pyridine nucleo-
3-Deazapyrimidine analogs produced significant sides 5a–h and 9a,b were employed, using both new and
growth inhibition against L-1210 leukemia cells in vitro and established methods (Strekowski et al., 2000; El-Sayed
have shown antiviral activity against RNA viruses (Abdou et al., 2009) (Schemes 1, 2). Microwave irradiation (methods
and Strekowski, 2000; Shi and Schinazi, 2001; Abdou A and B) was used to obtain the desired products 5a–h,
et al., 2002, 2004; El Sayed et al., 2008). However, the use 9a,b in short time (ꢀ<ꢀ10 min) under solvent-free conditions.
of some anticancer drugs has led to the development of In method A, silica gel was used as a catalyst to facilitate
drug resistance, and some compounds are toxic (Shi and the reaction between 2(1H)-pyridones 1a–h, 7a–c and
Schinazi, 2001; Reverdito et al., 2012). Consequently, it 1,2,3,4-tetra-O-acetyl-α-d-arabinopyranose (3) to produce
is essential to discover novel nucleosides as drug can- 3-cyano-2-(2″,3″,4″-tri-O-acetyl-β-d-arabinopyranosyloxo)
didates that may have low toxicity and more selectivity. pyridines5a–h and9a,b in 84–91% yields. The same nucleo-
Thus, extensive efforts have been conducted on various sides 5a–h and 9a,b (Schemes 1 and 2) were obtained
chemical modifications of nucleoside derivatives through in high yields under microwave irradiation using the

136ꢀ
ꢀI.M. Abdou et al.: Fast and efficient microwave synthetic methods
Me
NC
O
N
R
Ar
Microwave synthesis
(method A)
(method C)
N
Me
N
Ar
Conventional synthesis
N
R
NC
O
N
H
N
AcO
AcO
OAc
O
O
AcO
3
1a-h
AcO
OAc
OAc
AcO
5a-h
O
AcO
4
Me
5a
5b
5e: R = Ph, Ar = Ph
: R = Me, Ar = Ph
: R = Me, A r= 4-BrC6H4
Br
OAc
5f: R = Ph, Ar = 4-BrC6H4
5g: R = Ph, Ar = 4-ClC6H4
Ar
NC
N
Microwave synthesis
(method B)
(method D)
N
5c: R = Me, Ar = 3-ClC6H4
5d: R = Me, Ar = 4-MeC6H4 5h: R = Ph, Ar = 4-MeC6H4
Conventional synthesis
O
K
N
R
2a-h
Scheme 1ꢁSynthetic pathways of 2-(tri-O-acetyl-β-d-arabinopyranosyloxo)pyridines 5a–h.
potassium salt of 2(1H)-pyridone 2a–h or 8a,b and 2,3,5-tri- at ν 1754 cm-1 due to the presence of acetoxy carbonyl
O-acetyl-α-d-arabinopyranosyl bromide (4) in acetone- groups. The IR spectrum of 5g does not have a peak that
DMF (method B). For example, 3-cyano-4-methyl-6-phenyl- would correspond to the carbonyl carbon at the pyridine
5-(4′-chlorophenylazo)-2(1H)-pyridone (1g) was allowed C-2, which indicates that the sugar moiety is linked to
to react with 2,3,4-tri-O-acetyl-α-d-arabinopyranosyl the pyridine ring through the oxygen atom at C-2 giving
bromide (4) under microwave irradiation for 2 min to O-glycoside. The data obtained from 1H NMR spectroscopy
produce
3-cyano-4-methyl-2-(2″,3″,4″-tri-O-acetyl-β-d- support this structure elucidation. Coupling constants
arabinopyranosyloxy)-6-phenyl-5-(4′-chlorophenylazo) were used to establish conformations in solution by the
pyridine (5g) in 88% yield. The same products 5a–h and method of averaging of spin-spin coupling (Booth, 1964;
9a,b can be obtained by using expensive and incon- Feltkamp and Franklin, 1965; Bozo and Kuszmann, 2000;
venient two synthetic methods C and D. In method Andrew and Walter, 2001). The spin-spin coupling JH1′-H2′ ꢀ<ꢀ
C, 2(1H)-pyridone 1a–h is allowed to react with hexa- 4 Hz clearly shows that compound 5g is a β-isomer.
methyldisilazane (HMDS) and ammonium sulfate to form
The COSY and NOESY spectra were used to assign
a 2-silyloxypyridine intermediate product after 48 h. Then cross-peak interactions. In compound 5g, data obtained
the silyl intermediate is subjected to the reaction in situ, from NOESY spectrum show that there is no cross-peak
under anhydrous conditions, with 1,2,3,4-tetra-O-acetyl- interaction between the anomeric proton H-1′ and the
α-d-arabinopyranose (3) in the presence of anhydrous ortho-aromatic protons at C-2 and C-6, indicating that this
tin(IV)chloride to produce the corresponding product compound is an O-glycoside. This structural information
13
5a–h. In method D, 2-pyridone K-salt is a precursor to is supported by analysis of heteronuclear correlation 1H- C
the same arabinosides 5a–h. This reaction takes 6 h for (Ghmbc) chemical shifts. Ghmbc spectral analysis shows
completion.
that the anomeric proton has cross-peak interactions with
The structures of obtained products 5, 6, 9 and 10 C-1′, C-2′ and C-3′ of the sugar moiety, whereas there are no
were established and confirmed on the basis of their cross-peak interactions between the anomeric proton H-1′
elemental analyses and spectral data (MS, IR, 1D and and ortho-aromatic carbons at C-2 and C-6. This is further
2D NMR). For example, compound 5g with a molecular evidence of the formation of O-glycoside (Schemes 1–3).
formula C30H27N4O8Cl (MS, m/z 606) shows IR absorption Other compounds 5 were analyzed in a similar way.
Me
Me
Ar
Ar
NC
O
N
R
NC
O
N
R
Et3N/MeOH
or
N
N
AcO
HO
O
O
dry NH3/MeOH
AcO
HO
N
N
AcO
5a-h
OH
6a-h
6a
: R = Me, Ar = Ph
6e
: R = Ph, Ar = Ph
6b
: R = Me, Ar = 4-BrC6H4
6c: R = Me, Ar = 3-ClC6H4
6f: R = Ph, Ar = 4-BrC6H4
6g: R = Ph, Ar = 4-ClC6H4
6d: R = Me, Ar = 4-MeC6H4 6h: R = Ph, Ar = 4-MeC6H4
Scheme 2ꢀSynthesis of 2-(β-d-arabinopyranosyloxy)pyridines 6a–h.

I.M. Abdou et al.: Fast and efficient microwave synthetic methodsꢀ
ꢀ137
R
R
N
CN
O
CN
O
aq. KOH
Ph
N
H
Ph
K
8a,b
7a,b
(method C)
HMDS
(NH4)2SO4
(method A)
(method B)
4
R
N
R
CN
3
NC
O
AcO
SnCl4
Ph
OSi(Me)3
O
AcO
N
Ph
11a,b
9a,b
AcO
Et3N/MeOH
or
dry NH3/MeOH
R
N
NC
O
9a,10a: R = Me
9b,10b
: R = CF3
HO
O
HO
Ph
OH
10a,b
Scheme 3ꢁSynthetic pathways of 2-(β-d-arabinopyranosyloxy)pyridines 9a,b and 10a,b.
1H COSY, NOESY, DEPT, H 13C HMQC and H 13C HMBC experiments
on Varian Gemini spectrometers using Me4Si as an internal stand-
ard. The EI mass spectra were recorded on Shimadzu LCMS-QP 800
LC-MS and AB-4000 Q-trap LC-MS/MS spectrometers. Elemental
analysis was obtained from the Central Laboratories Unit (CLU) at
United Arab Emirates University. Thin-layer chromatography (TLC)
was carried out on precoated Merck silica gel F254 plates and UV light
was used for visualization. Column chromatography was performed
on a Merck silica gel. The reagents were purchased from Aldrich and
used without further purification.
1
1
Conclusion
New and efficient methods using microwave irradiation
to produce pyridine arabinosides 5a–h and 9a,b were
described. The solvent-free reaction between 2-pyri-
dones and an acetylated arabinose catalyzed by silica gel
produced the targeted products in high yield. The same
products 5a–h and 9a,b were obtained in high yield
under microwave irradiation using an activated sugar in
acetone-DMF in the absence of any catalyst. Structures of
the obtained products were confirmed using 1D and 2D
NMR experiments. 1H 1H NMR and 1H 13C NMR correlations
were used to confirm the suggested structures of O-nucleo-
side products 5–10.
General procedure for synthesis of 3-cyano-2-(2″,3″,4″-tri-O-
acetyl-β-d-arabinopyranosyloxy)pyridines 5a–h and 9a,b.
Microwave method AꢁA solution of 2(1H)-pyridone 1a–h or 7a,b
(1.0 mmol) and 1,2,3,5-tetra-O-acetyl-α-d-arabinose (3) (0.32 g, 1.0
mmol) in a mixture of dichloromethane/methanol (80:20) was
treated with silica gel (200–400 mesh, 1.0 g), and then the solvent
was removed by evaporation. The solid residue was transferred into
a 10-mL vial and irradiated for 2–3 min using the CEM Microwave
system. Purification by flash chromatography (hexanes/EtOAc, 4:1
to 7:3) was used to afford the desired nucleoside products 5a–h or
9a,b.
Experimental section
Microwave method BꢁTo a solution of 2(1H)-pyridone K-salt 2a–h
or 8a,b (10 mmol) in acetone (5 mL), a solution of 2,3,5-tri-O-acetyl-α-
d-arabinopyranosyl bromide (4) (3.79 g, 11 mmol) in acetone (5 mL)
was added with stirring at room temperature. The mixture was irra-
diated for 6–8 min using the CEM Microwave system and then the
solvent was removed under reduced pressure. Flash column was
General
Microwave synthesis was conducted using the CEM Microwave
system. Melting points were determined on a Gallenkamp appa-
ratus using Pyrex capillaries. Infrared spectra were recorded with
a Thermo Nicolet Nexus 470 FT-IR spectrometer using potassium
bromide disks. 1H NMR, 13C NMR and 2D NMR spectra were recorded, used to purify the product using hexanes/EtOAc (4:1–7:3) as eluent to
and the H and 13C H NMR signals were assigned by means of H afford the desired products 5a–h or 9a,b.
1
1
1

138ꢀ
ꢀI.M. Abdou et al.: Fast and efficient microwave synthetic methods
Conventional synthesis method C (silyl method)ꢁA mixture of 3-Cyano-4,6-dimethyl-2-(2″,3″,4″-Tri-O-acetyl-β-d-arabino-
2(1H)-Pyridone 1a–h or 7a,b (10.0 mmol), anhydrous hexamethyl- pyranosyloxy)-5-(4′ -chlorophenylazo)pyridine (5c)ꢁMethod
disilazane (HMDS) (25 mL) and catalytic amount of ammonium sulfate A, reaction time 3 min, yield 89%; method B, reaction time 8 min,
(0.02 g) was stirred and heated under reflux for 48 h. The excess of yield 80%; method C, reaction time 53 h, yield 49%; method D,
HMDS was removed under reduced pressure, providing the silylated reaction time 19 h, yield 66%; mp 118°C; IR ν 2230 (C≡N), 1750
base as a colorless oil. To a cold solution of the silylated base in dry (Cꢀ=ꢀO) cm-1; 1H NMR (400 MHz, CDCl3): δ 2.03, 2.11 and 2.18 (3s, 9H,
MeCN (30 mL) a solution of 1,2,3,5-tetra-O-acetyl-α-d-arabinopyranose 3 CH3CO), 2.54 (s, 3H, CH3), 2.57 (s, 3H, CH3), 3.69, 3.72 (dd, 1H, H-5a″,
(3) (3.49 g, 11.0 mmol) in dry MeCN (10 mL) was added followed by Jꢂ=ꢂ4.0 Hz and 8.4 Hz), 4.10, 4.15 (dd, 1H, H-5b″, Jꢂ=ꢂ4.0, Hz and 8.4
the addition of tin(IV) chloride (1.60 mL, 13.0 mmol). The mixture was Hz), 5.23–5.25 (m, 2H, H-2″ and H-4″), 5.27 (d, 1H, H-3″, Jꢂ=ꢂ3.2 Hz),
stirred at 0°C for 20 min, then at room temperature for an additional 6.38 (d, 1H, H-1″, Jꢂ=ꢂ2.8 Hz), 7.44 (d, 2H, Ar-H, Jꢂ=ꢂ4.8 Hz); 7.75 (d, 2H,
4–8 h until the reaction was completed as determined by TLC analy- Ar-H, Jꢂ=ꢂ4.8 Hz); 13C NMR (100 MHz, CDCl3): δ 17.8 (CH3), 20.8, 2.86
sis, then poured into saturated NaHCO3 solution (50 mL) and extracted and 20.9 (3 CH3CO), 23.1 (CH3), 59.5 (C-5″), 65.3 (C-4″), 67.4 (C-3″),
with CHCl3 (3 ꢀ×ꢀ 50 mL). The extract was dried over anhydrous MgSO4, 68.5 (C-2″), 92.5 (C-1″), 97.1 (C-3), 113.7 (C≡N), 123.9–155.5 (Ar-C),
filtered and concentrated under reduced pressure. Silica gel chroma- 160.0 (C-2), 169.1, 169.7 and 170.5 (3 Cꢀ=ꢀO); EI-MS: m/z 546 (M+H+).
tography of the residue eluting with gradient MeOH (0–2%) in CHCl3 Anal. Calcd for C25H25N4O8Cl: C, 55.10; H, 4.62; N, 10.28. Found: C,
afforded pure nucleoside 5a–h or 9a,b.
55.02; H, 4.33; N, 9.98.
Conventional synthesis method DꢁTo a solution of 2(1H)-pyridone 3-Cyano-4,6-dimethyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino-
1a–h (10.0 mmol) in DMF (10.0 mL) potassium hydride (1.90 g, 4.76 pyranosyloxy)-5-(4′-methylphenylazo)pyridine (5d)ꢁMethod A,
mmol) was added under a nitrogen atmosphere and the suspension reaction time 3 min, yield 84%; method B, reaction time 8 min, yield
was stirred at 60°C for 2 h. 2,3,4-Tri-O-acetyl-α-d-arabinopyranosyl 82%; method C, reaction time 53 h, yield 49%; method D, reaction
1
bromide (4) (4.91 g, 14.5 mmol) was added and the mixture was time 19 h, yield 65%; mp 120°C; IR ν 2227 (C≡N), 1749 (Cꢀ=ꢀO) cm-1; H
stirred at room temperature for 19–20 h until the reaction was com- NMR (400 MHz, CDCl3): δ 2.03, 2.12 and 2.17 (3s, 9H, 3 CH3CO), 2.39 (s,
pleted as determined by TLC analysis. The solvent was evaporated 3H, CH3), 2.51 (s, 3H, CH3), 2.54 (s, 3H, CH3), 3.70, 3.72 (dd, 1H, H-5a″,
and the residue was treated with water (30 mL) and extracted with Jꢂ=ꢂ2.4, 8.0 Hz), 4.12, 4.15 (dd, 1H, H-5b″, Jꢂ=ꢂ2.4, 3.6 Hz), 5.23–5.25 (m,
CHCl3 (3 ꢀ×ꢀ 30 mL). The extract was dried over Na2SO4, filtered and 2H, H-3″ and H-4″), 5.27 (t, 1H, H-2″, Jꢂ=ꢂ6.4 Hz), 6.36 (d, 1H, H-1″,
concentrated under reduced pressure. The residue was subjected to Jꢂ=ꢂ2.8 Hz), 7.27 (d, 1H, Ar-H, Jꢂ=ꢂ8.0 Hz); 7.71 (d, 1H, Ar-H, Jꢂ=ꢂ8.0 Hz);
silica gel chromatography (50 g) eluting with gradient MeOH (0–2%) 13C NMR (100 MHz, CDCl3): δ 17.5 (CH3), 20.8, 21.0 and 21.6 (3 CH3CO),
in CHCl3 to afford pure product 5a–h.
22.8 (CH3), 29.7 (CH3), 59.5 (C-5″), 65.4 (C-4″), 67.4 (C-3″), 68.6 (C-2″),
92.4 (C-1″), 96.8 (C-3), 113.8 (C≡N), 122.5–154.9 (Ar-C), 159.6 (C-2),
3-Cyano-4,6-dimethyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino- 169.1, 169.9 and 170.5 (3 Cꢀ=ꢀO); EI-MS: m/z 525 (M+H+). Anal. Calcd
pyranosyloxy)-5-phenylazopyridine (5a)ꢁMethod A, reaction for C26H28N4O8: C, 59.54; H, 5.38; N, 10.68. Found: C, 59.33; H, 5.09; N,
time 3 min, yield 85%; method B, reaction time 7 min, yield 81%; 10.53.
method C, reaction time 53 h, yield 49%; method D, reaction time 20
h, yield 58%; mp 124°C; IR ν 2229 (C≡N), 1750 (Cꢀ=ꢀO) cm-1; 1H NMR (200 3-Cyano-4-methyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino-
MHz, CDCl3): δ 2.05, 2.10 and 2.17 (3s, 9H, 3 CH3CO), 2.25 (s, 3H,CH3), pyranosyloxy)-5-phenylazo-6-phenylpyridine (5e)ꢁMethod A,
2.61 (s, 3H,CH3), 3.76, 3.81 (dd, 1H, H-5a″, Jꢂ=ꢂ3.8 Hz and 8.4 Hz), 4.15, reaction time 2 min, yield 90%; method B, reaction time 8 min, yield
4.25 (dd, 1H, H-5b″, Jꢂ=ꢂ3.8 Hz and 8.4 Hz), 5.31–5.32 (m, 3H, H-2″, H-3″ 85%; method C, reaction time 53 h, yield 49%; method D, reaction
and H-4″), 6.44 (d, 1H, H-1″, Jꢂ=ꢂ2.2 Hz), 7.31–7.89 (m, 5H, Ar-H); 13C time 19 h, yield 63%; mp 162°C; IR ν 2229 (C≡N), 1737 (Cꢀ=ꢀO) cm-1; H
1
NMR (50 MHz, CDCl3): δ 17.8 (CH3), 20.9, 20.95 and 21.0 (3 CH3Cꢀ=ꢀO), NMR (200 MHz, CDCl3): δ 2.11, 2.19 and 2.25 (3s, 9H, 3 CH3CO), 2.61
23.0 (CH3), 59.5 (C-5″), 65.3 (C-4″), 67.4 (C-3″), 68.5 (C-2″), 92.3 (C-1″), (s, 3H, CH3), 3.76, 3.82 (dd, 1H, H-5a″, Jꢂ=ꢂ4.2 Hz and 8.4 Hz), 4.16, 4.23
96.8 (C-3), 113.6 (C≡N), 122.5–154.7 (Ar-C), 159.4 (C-2), 168.7, 169.3 and (dd, 1H, H-5b″, Jꢂ=ꢂ4.2 Hz and 8.4 Hz), 5.34–5.35 (m, 3H, H-2″, H-3″ and
170.1 (3 Cꢀ=ꢀO); EI-MS: m/z 550 (M+K+). Anal. Calcd for C25H26N4O8: C, H-4″), 6.47 (d, 1H, H-1″, Jꢂ=ꢂ2.0 Hz), 7.24–7.75 (m, 10H, Ar-H); 13C NMR
58.82; H, 5.13; N, 10.97. Found: C, 58.54; H, 5.03; N, 11.02.
(50 MHz, CDCl3): δ 18.3 (CH3), 20.9, 21.0 and 21.1 (3 CH3CO), 59.8 (C-5″),
65.5 (C-4″), 67.6 (C-3″), 68.6 (C-2″), 92.7 (C-1″), 97.9 (C-3), 113.7 (C≡N),
3-Cyano-4,6-dimethyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino- 122.7–146.8 (Ar-C), 152.0 (C-2), 168.7, 169.2 and 170.1 (3 Cꢀ=ꢀO); EI-MS:
pyranosyloxy)-5-(4′ -bromophenylazo)pyridine (5b)ꢁMethod A, m/z 572 (M). Anal. Calcd for C30H28N4O8: C, 62.93; H, 4.93; N, 9.79.
reaction time 3 min, yield 86%; method B, reaction time 7 min, yield Found: C, 62.76; H, 4.65; N, 9.83.
81%; method C, reaction time 53 h, yield 49%; method D, reaction time
1
19 h, yield 61%; mp 126°C; IR ν 2230 (C≡N), 1750 (Cꢀ=ꢀO) cm-1; H NMR 3-Cyano-4-methyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino-
(400 MHz, CDCl3): δ 2.03, 2. 11 and 2.17 (3s, 9H, 3 CH3CO), 2.54 (s, 3H, pyranosyloxy)-6-phenyl-5-(4′ -bromophenylazo)pyridine
CH3), 2.57 (s, 3H, CH3), 3.68, 3.72 (dd, 1H, H-5a″, Jꢂ=ꢂ4.8 Hz and 8.4 Hz), (5f)ꢁMethod A, reaction time 2 min, yield 89%; method B, reac-
4.10, 4.15 (dd, 1H, H-5b″, Jꢂ=ꢂ4.8 Hz and 8.4 Hz), 5.23–5.28 (m, 3H, H-2″, tion time 7 min, yield 82%; method C, reaction time 55 h, yield 57%;
H-3″, H-4″); 6.38 (d, 1H, H-1″, Jꢂ=ꢂ2.8 Hz), 7.68 (d, 2H, Ar-H, Jꢂ=ꢂ8.8 Hz), method D, reaction time 20 h, yield 72%; mp 165°C; IR ν 2229 (C≡N),
1
7.61 (d, 2H, Ar-H, Jꢂ=ꢂ8.8 Hz); 13C NMR (100 MHz, CDCl3): δ 17.8 (CH3), 1742 (Cꢀ=ꢀO) cm-1; H NMR (200 MHz, CDCl3) δ 2.12, 2.19 and 2.26 (3s,
20.8, 20.85 and 20.9 (3 CH3CO), 23.1 (CH3), 59.5 (C-5″), 65.3 (C-4″), 67.4 9H, 3 CH3CO), 2.63 (s, 3H, CH3), 3.75, 3.82 (dd, 1H, H-5a″, Jꢂ=ꢂ4.4, 8.2 Hz),
(C-3″), 68.6 (C-2″), 92.5 (C-1″), 97.1 (C-3), 113.7 (C≡N), 124.1–155.5 (Ar-C), 4.18, 4.27 (dd, 1H, H-5b″, Jꢂ=ꢂ4.4 Hz and 8.2 Hz), 5.31–5.36 (m, 3H, H-2″,
160.0 (C-2), 169.1, 170.0 and 170.5 (3 Cꢀ=ꢀO); EI-MS: m/z 589 (M+H+). Anal. H-3″ and H-4″), 6.50 (d, 1H, H-1″, Jꢂ=ꢂ1.6 Hz), 7.26–7.70 (m, 9H, Ar-H);
Calcd for C25H25N4O8Br: C, 50.95; H, 4.28; N, 9.51. Found: C, 51.24; H, 13C NMR (50 MHz, CDCl3): δ 18.5 (CH3), 20.9, 21.0 and 21.1 (3 CH3CO),
4.34; N, 9.66.
59.7 (C-5″), 65.4 (C-4″), 67.5 (C-3″), 68.5 (C-2″), 92.7 (C-1″), 98.0 (C-3),

I.M. Abdou et al.: Fast and efficient microwave synthetic methodsꢀ
ꢀ139
113.6 (C≡N), 124.1–154.5 (Ar-C), 159.6 (C-2), 168.7, 169.2 and 170.1 (3 and H-4″), 6.48 (d, 1H, H-1″, Jꢂ=ꢂ2.8 Hz), 7.43–7.47 (m, 3H, Ar-H), 7.71 (s,
Cꢀ=ꢀO); EI-MS: m/z 649 (M-H+). Anal. Calcd for C30H27N4O8Br: C, 55.31; 1H, pyridine H-5), 7.91–7.97 (m, 2H, Ar-H); 19F NMR (376 MHz, CDCl3):
H, 4.18; N, 8.60. Found: C, 55.42; H, 3.95; N, 8.44.
δ (-63.89) (s, CF3); 13C NMR (100 MHz, CDCl3): δ 20.7, 20.75 and 20.8
(3 CH3CO), 59.4 (C-5″), 65.1 (C-4″), 67.2 (C-3″), 68.5 (C-2″), 92.4 (C-3),
3-Cyano-4-methyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino- 93.0 (C-1″), 111.0 (C-5), 111.4 (C≡N), 119.8 (CF3), 127.7–135.6 (Ar-C), 144.5
pyranosyloxy)-6-phenyl-5-(4′ -chlorophenylazo)pyridine (C-4), 160.3 (C-6), 162.6 (C-2); 169.1, 170.1 and 170.5 (3 Cꢀ=ꢀO); EI-MS:
(5g)ꢁMethod A, reaction time 2 min, yield 91%; method B, reac- m/z 545 (M+Na+). Anal. Calcd for C24H21F3N2O8: C, 55.18; H, 4.05; N,
tion time 6 min, yield 84%; method C, reaction time 52 h, yield 5.36. Found: C, 55.24; H, 4.14; N, 5.45.
58%; method D, reaction time 19 h, yield 77%; mp 146°C; IR ν 2228
1
(C≡N), 1749 (Cꢀ=ꢀO) cm-1; H NMR (200 MHz, CDCl3): δ 2.13, 2.19 and
2.27 (3s, 9H, 3 CH3CO), 2.64 (s, 3H,CH3), 3.77, 3.85 (dd, 1H, H-5a″,
General procedure for synthesis of 2-(β-
Jꢂ=ꢂ3.0 Hz and 7.8 Hz), 4.20, 4.30 (dd, 1H, H-5b″, Jꢂ=ꢂ3.0 Hz and 7.8
d-arabinopyranosyloxy)-3-cyanopyridines
Hz), 5.37–5.38 (m, 3H, H-2″, H-3″ and H-4″), 6.52 (d, 1H, H-1″, J ꢀ=ꢀ1.6
Hz), 7.28–7.72 (m, 9H, Ar-H); 13C NMR (50 MHz, CDCl3): δ 18.5 (CH3),
6a–h and 10a,b
20.8, 21.0 and 21.1 (3 CH3CO), 59.7 (C-5″), 65.4 (C-4″), 67.5 (C-3″), 68.5
(C-2″), 92.7 (C-1″), 97.9 (C-3), 113.6 (C≡N), 123.1–154.5 (Ar-C), 159.6
(C-2), 168.7, 169.5 and 170.1 (3 CO); EI-MS: m/z 606 (M). Anal. Calcd
for C30H27N4O8Cl: C, 59.36; H, 4.48; N, 9.23. Found: C, 59.33; H, 4.54;
N, 9.12.
Method E Triethylamine (1.0 mL) was added to a solution of pro-
tected arabinosides 5a–h or 10a,b (1.0 mmol) in MeOH (10 mL with
three drops of water). The mixture was stirred overnight at room tem-
perature and then concentrated under reduced pressure. To remove
traces of triethylamine, the residue was treated with MeOH and the
mixture was concentrated (2ꢀ×ꢀ). The resultant solid was purified
using silica gel chromatography eluting with chloroform/methanol
(9:1). Analytically pure product 6a–h or 10a,b was obtained by crys-
tallization from MeOH.
3-Cyano-4-methyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino-
pyranosyloxy)-6-phenyl-5-(4′ -methylphenylazo)pyridine
(5h)ꢁMethod A, reaction time 2 min, yield 88%; method B, reac-
tion time 8 min, yield 80%; method C, reaction time 56 h, yield 51%;
method D, reaction time 19 h, yield 69%; mp 137°C; IR ν 2227 (C≡N),
1
Method F Dry ammonia gas was passed into a solution of protected
arabinosides 5a–h or 9a,bꢁ(0.5 g) in dry methanol (20 mL) at 0°C for
30 min. The mixture was stirred until the reaction was completed as
shown by TLC analysis (chloroform/methanol, 9:1) and then concen-
trated under reduced pressure to afford a solid residue. The obtained
solid was purified using silica gel chromatography eluting with
chloroform/methanol (9:1) followed by crystallization from MeOH to
furnish analytically pure product 6a–h or 10a,b.
1751 (Cꢀ=ꢀO) cm-1; H NMR (200 MHz, CDCl3): δ 2.11, 2.20 and 2.25 (3s,
9H, 3 CH3CO), 2.43 (s, 3H, CH3), 2.60 (s, 3H, CH3) 3.74, 3.82 (dd, 1H,
H-5a″, Jꢂ=ꢂ4.2 Hz and 8.2 Hz), 4.20, 4.30 (dd, 1H, H-5b″, Jꢂ=ꢂ4.2 Hz and 8.2
Hz), 5.32–5.36 (m, 3H, H-2″, H-3″ and H-4″), 6.48 (d, 1H, H-1″, Jꢂ=ꢂ2.4
Hz), 7.24–7.76 (m, 9H, Ar-H); 13C NMR (50 MHz, CDCl3): δ 18.2 (CH3),
20.9, 20.95 and 21.0 (3 CH3CO), 21.7 (CH3), 59.8 (C-5″), 65.5 (C-4″), 67.6
(C-3″), 68.5 (C-2″), 92.6 (C-1″), 97.7 (C-3), 113.6 (C≡N), 122.7–153.7 (Ar-C),
159.3 (C-2), 168.7, 169.5 and 170.1 (3 Cꢀ=ꢀO); EI-MS: m/z 585 (M-H+). Anal.
Calcd for C31H30N4O8: C, 63.47; H, 5.15; N, 9.55. Found: C, 63.32; H, 5.07;
N, 9.74.
2-(β-d-Arabinopyranosyloxy)-3-cyano-4,6-dimethyl-5-
phenylazopyridine (6a)ꢁMethod E, yield 88%; method F, yield
1
80%; mp 156°C; IR ν 3417 (OH), 2233 (C≡N) cm-1; H NMR (200 MHz,
3-Cyano-4-methyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino-
pyranosyloxy)-6-phenylpyridine (9a)ꢁMethod A, reaction time 3
min, yield 88%; method B, reaction time 6 min, yield 85%; method
C, reaction time 53 h, yield 58%. mp 137°C; IR ν 2227 (C≡N), 1740
DMSO-d6): δ 2.63 (s, 3H, CH3), 2.64 (s, 3H, CH3), 3.55–3.89 (m, 5H, H-2″,
H-3″, H-4″ and 5″a,b), 4.80–5.39 (3 OH, exchangeable with D2O), 6.01
(d, Jꢂ=ꢂ6.4 Hz, H-1″), 7.53–7.95 (m, 5H, Ar-H); 13C NMR (100 MHz, DMSO-
d6): δ 17.6 (CH3), 23.0 (CH3), 65.6 (C-5″), 66.9 (C-4″), 69.7 (C-3″), 72.1
(C-2″), 95.9 (C-1″), 97.1 (C-3), 113.8 (C≡N), 121.7–154.3 (Ar-C), 160.4 (C-2);
EI-MS: m/z 385 (M+H+). Anal. Calcd for C19H20N4O5: C, 59.37; H, 5.24; N,
14.58. Found: C, 59.26; H, 5.09; N, 14.81.
1
(Cꢀ=ꢀO) cm-1; H NMR (400 MHz, CDCl3): δ 2.10, 2.19 and 2.23 (3s, 9H,
3 CH3CO), 2.56 (s, 3H, CH3), 3.76, 3.80 (dd, 1H, H-5a″, Jꢂ=ꢂ3.2 Hz and
8.0 Hz), 4.18, 4.23 (dd, 1H, H-5b″, Jꢂ=ꢂ3.2 Hz and 8.0 Hz), 5.32–5.34 (m,
3H, H-2″, H-3″ and H-4″), 6.49 (d, 1H, H-1″, Jꢂ=ꢂ1.6 Hz), 7.38 (s, 1H,
pyridine H-5), 7.43–7.48 (m, 3H, Ar-H), 7.95–8.00 (m, 2H, Ar-H); 13C
NMR (100 MHz, CDCl3): δ 20.5 (CH3), 20.75, 20.8 and 20.9 (3 CH3CO),
59.8 (C-5″), 65.5 (C-4″), 67.6 (C-3″), 68.6 (C-2″), 92.6 (C-1″), 96.0 (C-3),
114.1 (C≡N), 115.9 (C-5), 127.3–136.8 (Ar-C), 155.6 (C-4), 157.8 (C-6),
161.6 (C-2), 169.1, 170.0 and 170.5 (3 CO); EI-MS: m/z 468 (M). Anal.
Calcd for C24H24N2O8: C, 61.53; H, 5.16; N, 5.98. Found: C, 61.49; H,
4.99; N, 5.95.
2-(β-d-Arabinopyranosyloxy)-3-cyano-4,6-dimethyl-5-(4′ -
bromophenylazo)pyridine (6b)ꢁMethod E, yield 88%; method F,
1
yield 82%; mp 215°C; IR ν 3405 (OH), 2232 (C≡N) cm-1; H NMR (400
MHz, DMSO-d6): δ 2.60 (s, 3H, CH3), 2.61 (s, 3H, CH3), 3.55–3.83 (m,
2H, H-2″, H-3″, H-4″ and 2H-5″), 4.80–5.37 (3 OH, exchangeable with
D2O), 5.97 (d, H-1″, Jꢂ=ꢂ6.8 Hz), 7.71–7.84 (m, 4H, Ar-H); 13C NMR (100
MHz, DMSO-d6): δ 17.5 (CH3), 23.0 (CH3), 65.5 (C-5″), 66.8 (C-4″), 69.6
(C-3″), 72.1 (C-2″), 96.1 (C-1″), 97.2 (C-3), 113.9 (C≡N), 123.7–155.1 (Ar-C),
160.9 (C-2); EI-MS: m/z 462 (M). Anal. Calcd for C19H19N4O5Br: C, 49.26;
H, 4.13; N, 12.09. Found: C, 49.24; H, 4.06; N, 12.33.
3-Cyano-6-phenyl-2-(2″,3″,4″-tri-O-acetyl-β-d-arabino-
pyranosyloxy)-4-trifluromethyl pyridine (9b)ꢁMethod A, reac-
tion time 2 min, yield 92%; method B, reaction time 4 min, yield
89%, method C; reaction time 49 h, yield 45%. mp 112°C; IR ν 2236
(C≡N), 1744 (Cꢀ=ꢀO) cm-1; 1H NMR (400 MHz, CDCl3) δ 2.02, 2.10 and 2.17
(3s, 9H, 3 CH3CO), 3.71, 3.75 (dd, 1H, H-5a″, Jꢂ=ꢂ3.2 Hz and 8.0 Hz), 4.12,
4.17 (dd, 1H, H-5b″, Jꢂ=ꢂ3.2 Hz and 8.0 Hz), 5.24–5.32 (m, 3H, H-2″, H-3″
2-(β-d-Arabinopyranosyloxy)-3-cyano-4,6-dimethyl-5-(4′-
chlorophenylazo)pyridine (6c)ꢁMethod E, yield 90%; method F,
1
yield 88%; mp 201°C; IR ν 3375 (OH), 2234 (C≡N) cm-1; H NMR (400
MHz, DMSO-d6): δ 2.60 (s, 3H, CH3), 2.61 (s, 3H, CH3), 3.35–3.82 (m, 5H,

140ꢀ
ꢀI.M. Abdou et al.: Fast and efficient microwave synthetic methods
H-2″, H-3″, H-4″ and 2 H-5″), 4.80–5.36 (3 OH, exchangeable with D2O), and2H-5″), 4.84 (d, OH, Jꢂ=ꢂ6.2 Hz, exchangeable with D2O), 4.94 (d, OH,
5.97 (d, H-1″, Jꢂ=ꢂ6.8 Hz), 7.70 (d, 2H, Ar-H, Jꢂ=ꢂ8.8 Hz), 7.92 (d, 2H, Ar-H, Jꢂ=ꢂ5.0 Hz, exchangeable with D2O), 5.43 (d, OH, Jꢂ=ꢂ5.0 Hz, exchange-
Jꢂ=ꢂ8.8 Hz); 13C NMR (100 MHz, DMSO-d6): δ 17.5 (CH3), 22.9 (CH3), 65.5 able with D2O), 6.08 (d, H-1″, Jꢂ=ꢂ6.4 Hz), 7.48–7.75 (m, 9H, Ar-H); 13C
(C-5″), 66.8 (C-4″), 69.6 (C-3″), 72.1 (C-2″), 96.1 (C-1″), 97.2 (C-3), 113.8 NMR (50 MHz, DMSO-d6): δ 18.1 (CH3), 65.5 (C-5″), 66.8 (C-4″), 69.7
(C≡N), 124.1–155.1 (Ar-C), 160.9 (C-2); EI-MS: m/z 457 (M+K+). Anal. (C-3″), 72.1 (C-2″), 97.1 (C-1″), 97.4 (C-3), 113.8 (C≡N), 123.9–153.7 (Ar-C),
Calcd for C19H19N4O5Cl: C, 54.49; H, 4.57; N, 13.38. Found: C, 54.71; H, 160.5 (C-2); EI-MS: m/z 503 (M+Na+). Anal. Calcd for C24H21N4O5Cl: C,
4.62; N, 13.19.
59.94; H, 4.40; N, 11.65. Found: C, 59.89; H, 4.25; N, 11.52.
2-(β-d-Arabinopyranosyloxy)-3-cyano-4,6-dimethyl-5-(4′- 2-(β-d-Arabinopyranosyloxy)-3-cyano-4-methyl-6-phenyl-5-(4′ -
methylphenylazo)pyridine (6d)ꢁMethod E, yield 89%; method F, methylphenylazo)pyridine (6h)ꢁMethod E, yield 88%; method F,
1
1
yield 85%; mp 210°C; IR ν 3378 (OH), 2233 (C≡N) cm-1; H NMR (400 yield 81%; mp 131°C; IR ν 3409 (OH), 2231 (C≡N) cm-1; H NMR (200
MHz, DMSO-d6): δ 2.47 (s, 3H, CH3), 2.61 (s, 3H, CH3), 2.62 (s, 3H, MHz, DMSO-d6): δ 2.38 (s, 3H, CH3), 2.51 (s, 3H, CH3), 3.36–3.81 (m, 5H,
CH3), 3.61–3.88 (m, 5H, H-2″, H-3″, H-4″ and 2 H-5″), 4.84–5.42 (3 OH, H-2″, H-3″, H-4″ and 2H-5″), 4.79 (d, OH, Jꢂ=ꢂ4.2 Hz, exchangeable with
exchangeable with D2O), 6.01 (d, H-1″, Jꢂ=ꢂ6.8 Hz), 7.49 (d, 2H, Ar-H, D2O), 4.89 (d, OH, Jꢂ=ꢂ3.6 Hz, exchangeable with D2O), 5.37 (d, OH, Jꢂ=ꢂ3.0
Jꢂ=ꢂ8.4 Hz), 7.86 (d, 2H, Ar-H, Jꢂ=ꢂ8.4 Hz); 13C NMR (100 MHz, DMSO-d6): Hz, exchangeable with D2O), 6.02 (d, H-1″, Jꢂ=ꢂ6.2 Hz), 7.33–7.61 (m, 9H,
δ 17.8 (CH3), 21.5 (CH3), 23.2 (CH3), 66.1 (C-5″), 67.4 (C-4″), 70.2 (C-3″), Ar-H); 13C NMR (50 MHz, DMSO-d6): δ 17.9 (CH3), 21.2 (CH3), 65.5 (C-5″),
72.7 (C-2″), 96.5 (C-1″), 97.7 (C-3), 114.5 (C≡N), 122.9–154.9 (Ar-C), 161.1 66.8 (C-4″), 69.7 (C-3″), 72.1 (C-2″), 97.0 (C-1″), 97.3 (C-3), 113.8 (C≡N),
(C-2); EI-MS: m/z 398 (M). Anal. Calcd for C20H22N4O5: C, 60.29; H, 5.57; 122.3–152.9 (Ar-C), 160.5 (C-2); EI-MS: m/z 561 (M+H+). Anal. Calcd for
N, 14.06%. Found: C, 60.12; H, 5.76; N, 14.28%.
C25H24N4O5: C, 65.21; H, 5.25; N, 12.17. Found: C, 65.09; H, 5.35; N, 12.28.
2-(β-d-Arabinopyranosyloxy)-3-cyano-4-methyl-6-phenyl-5- 2- ( β -d -Ar abinopyr anosylox y)-3- cyano - 4-methyl-6-
phenylazopyridine (6e)ꢁMethod E, yield 91%; method F, yield phenylpyridine (10a)ꢁMethod E, yield 88%; method F, yield 80%;
1
84%; mp 134°C; IR ν 3429 (OH), 2230 (C≡N) cm-1; H NMR (200 MHz, mp 151°C; IR ν 3426 (OH), 2222 (C≡N) cm-1; 1H NMR (200 MHz, DMSO-
DMSO-d6): δ 2.55 (s, 3H, CH3), 3.30–3.93 (m, 5H, H-2″, H-3″, H-4″ and d6): δ 2.50 (s, 3H, CH3), 3.64–3.88 (m, 5H, H-2″, H-3″, H-4″ and 2H-5″),
2H-5″), 4.84 (d, OH, Jꢂ=ꢂ4.4 Hz), 4.94 (d, OH, Jꢂ=ꢂ5.2 Hz), 5.43 (d, OH, 4.76–5.35 (3 OH, exchangeable with D2O), 6.06 (d, H-1″, Jꢂ=ꢂ6.6 Hz),
Jꢂ=ꢂ5.2 Hz, exchangeable with D2O), 6.08 (d, H-1″, Jꢂ=ꢂ6.2 Hz), 7.45–7.78 7.44–7.54 (m, 3H, Ar-H), 7.80 (s, 1H, pyridine H-5), 8.01–8.16 (m, 2H,
(m, 10H, Ar-H); 13C NMR (50 MHz, DMSO-d6): δ 17.9 (CH3), 65.5 (C-5″), Ar-H); 13C NMR (50 MHz, DMSO-d6): δ 20.1 (CH3), 65.6 (C-5″), 67.0
66.8 (C-4″), 69.7 (C-3″), 72.1 (C-2″), 97.0 (C-1″), 97.3 (C-3), 113.8 (C≡N), (C-4″), 69.7 (C-3″), 72.3 (C-2″), 94.8 (C-1″), 96.9 (C-3), 114.2 (C≡N), 115.2
122.2–153.2 (Ar-C), 160.3 (C-2). Anal. Calcd for C24H22N4O5: C, 64.57; H, (C-5), 126.9–136.1 (Ar-C), 155.7 (C-4), 156.1 (C-6), 161.8 (C-2); EI-MS:
4.97; N, 12.55. Found: C, 64.71; H, 4.78; N, 12.39.
m/z 365 (M+Na+). Anal. Calcd for C18H18N2O5: C, 63.15; H, 5.30; N, 8.18.
Found: C, 63.13; H, 5.34; N, 8.20.
2-(β-d-Arabinopyranosyloxy)-3-cyano-4-methyl-6-phenyl-5-(4′ -
bromophenylazo)pyridine (6f)ꢁMethod E, yield 89%; method F, 2- ( β -d -Ar abinopyr anosylox y)-3- cyano - 4-methyl-6-
yield 82%; mp 140°C; IR ν 3416 (OH), 2232 (C≡N) cm-1; H NMR (200 trifluromethylpyridine (10b)ꢁMethod E, yield 88%; method F,
1
MHz, DMSO-d6): δ 2.54 (s, 3H, CH3), 3.30–3.87 (m, 5H, H-2″, H-3″, yield 80%; mp 141°C; IR ν 3409 (OH), 2223 (C≡N) cm-1; H NMR (200
1
H-4″ and 2H-5″), 4.85 (d, OH, Jꢂ=ꢂ6.2 Hz, exchangeable with D2O), MHz, DMSO-d6): δ 3.54–3.83 (m, 5H, H-2″, H-3″, H-4″ and 2 H-5″), 4.75–
4.95 (d, OH, Jꢂ=ꢂ5.6 Hz, exchangeable with D2O), 5.43 (d, OH, Jꢂ=ꢂ5.2 5.35 (3 OH, exchangeable with D2O), 5.96 (d, Jꢀ=ꢀ6.6 Hz, H-1″), 7.50–7.52
Hz, exchangeable with D2O), 6.09 (d, H-1″, Jꢂ=ꢂ6.2 Hz), 7.50–7.87 (m, (m, 3H, Ar-H), 7.79 (s, 1H, pyridine H-5), 8.11–8.13 (m, 2H, Ar-H); 19F
9H, Ar-H); 13C NMR (50 MHz, DMSO-d6): δ 18.1 (CH3), 65.5 (C-5″), 66.8 NMR (376 MHz, CDCl3): δ (-61.42) (s, CF3); EI-MS: m/z 419 (M+Na+).
(C-4″), 69.7 (C-3″), 72.0 (C-2″), 97.1 (C-1″), 97.4 (C-3), 113.7 (C≡N), 124.1– Anal. Calcd for C18H15F3N2O5: C, 54.55; H, 3.81; N, 7.07. Found: C, 54.49;
153.6 (Ar-C), 160.5 (C-2). Anal. Calcd for C24H21N4O5Br: C, 54.87; H, 4.03; H, 3.75; N, 6.98.
N, 10.66. Found: C, 55.13; H, 4.33; N, 10.80.
Acknowledgments: The authors wish to thank the Depart-
2-(β -d-Arabinopyranosyloxy)-3-cyano-4-methyl-6-phenyl-5-(4′ -
chlorophenylazo)pyridine (6g)ꢁMethod E, yield 85%; method F,
ment of Chemistry, Faculty of Science, UAE University for
support and the use of spectroscopic analysis facilities.
yield 84%; mp 155°C; IR ν 3403 (OH), 2236 (C≡N) cm-1; H NMR (200
1
MHz, DMSO-d6): δ 2.54 (s, 3H, CH3), 3.32–3.92 (m, 5H, H-2″, H-3″, H-4″ Received May 31, 2012; accepted June 15, 2012
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