Optically active furanoids containing cytosine-, adenine-and nicotinamide-like moieties

Article abstract of DOI:10.1135/cccc19961223

3-Hydroxymethyl-5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2- methylfuran (2) prepared from 3-ethoxycarbonyl derivative 1 was converted to 3-chloromethyl-5-(2,3-O-isopropylidene-β-D-erythrofuranosyl)-2-methylfuran (3). Compound 3 reacted with cytosine

Full text of DOI:10.1135/cccc19961223

Optically Active Furanoids
1223
OPTICALLY ACTIVE FURANOIDS CONTAINING CYTOSINE-, ADENINE-
AND NICOTINAMIDE-LIKE MOIETIES
1
2,
3
4
Ali WERFELI , Svatava VOLTROVA *, Viktor PRUTIANOV and Josef KUTHAN
Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6,
Czech Republic; e-mail: 1 gebrila@vscht.cz, 2 svatava.voltrova@vscht.cz, 3 prutianv@vscht.cz,
4 kuthanj@vscht.cz
Received April 26, 1996
Accepted May 31, 1996
3-Hydroxymethyl-5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methylfuran (2) prepared from 3-
ethoxycarbonyl derivative 1 was converted to 3-chloromethyl-5-(2,3-O-isopropylidene-β-D-erythro-
furanosyl)-2-methylfuran (3). Compound 3 reacted with cytosine, adenine, 6-chloropurine,
6-mercaptopurine, and nicotinamide to corresponding optically active heterocyclic derivatives 5–10
and 14. The 6-chloro derivative 9 was converted to 6-alkoxy derivatives 11 and 12 by the reaction
with methanol or ethanol, respectively, in the presence of diazabicyclooctane. Dithionite reduction of
quaternary chloride 14 gave 1,4-dihydropyridine derivative 15 capable to transform ethyl phenylglyoxy-
late to optically active ethyl mandelate.
Key words: 5-Deoxy-β-D-ribofuranose derivatives; NADH model reduction.
In connection with our interest in biologically active chiral heterocycles we decided to
investigate some optically active furanoids. A number of these compounds are easily
available from various pentoses and simple 1,3-dicarbonyl reaction partners1. In this
communication we attempt to connect a chiral furanoid system with biochemically im-
portant cytosine-, adenine- and nicotinamide-like moieties. It has been believed2 that
optically active substances containing such fragments may exhibit antiviral and cytos-
tatic activities.
Ethyl 5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methylfuroate (1) prepared
by two-step synthesis from D-glucose and ethyl acetoacetate3 was used as starting ma-
terial. By its reduction with lithium aluminium hydride the 3-hydroxymethyl derivative 2
was obtained which with tosyl chloride under mild conditions gave the corresponding
3-chloromethyl-5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methylfuran (3) in-
stead of expected 3-toluenesulfonyl ester 4. Such uncommon behaviour may be ex-
plained by the following two-step process (Eq. (1)):
* The author to whom correspondence should be addressed.
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1224
Werfeli, Voltrova, Prutianov, Kuthan:
2 + TsCl + Py → 4 + PyH+ Cl– → 3 + PyH+ OTs– .
(1)
Similar unexpected behaviour has been so far observed, to our knowledge, only in one
case of tosylation at elevated temperature4. An useful approach to 3-chloromethyl deri-
vative 3 has finally been worked up on the basis of a direct reaction of alcohol 2 with
thionyl chloride.
Compound 3 was sensitive to hydrolysis with moist air and therefore it was allowed
to react with cytosine, adenine, 6-chloro- and 6-mercaptopurine without any purifica-
tion. Nucleophilicity of the reactants has been enhanced prior to the substitution by
transformation to corresponding sodium salts using sodium hydride in dimethylform-
amide5. It was found that the reaction with cytosine gave exclusively compound 5 sub-
stituted at the position 1, similarly to other alkylations6 of this substrate. On the other
Y
6
X
3a
4a
7
N
5
4
H-4R’
O
N
1’
8
X =
5a
2a
O
Me
H-4’
2
3’
S
9
N
N
2’
H2C3b
O
O
5’
Me
6’
Me
6"
Y = NH
6,
9,
2
Y = Cl
Y = OMe
11,
12,
13,
X = CO2Et
X = CH2OH
X = CH2Cl
Y = OEt
1,
Y = N (CH2CH2)3N Cl
2,
3,
4,
H2C3b
Y
6
X = CH2OTs
NH2
7
5
4
N
N
8
X =
2
N
9
5
6
N
4
N
X =
5,
2
O
N
Y = NH
7,
8,
3bCH2
2
Y = Cl
H
S
6
CH2
3b
4
7N
5
CONH2
Cl
5
N
8
10, X =
15, X =
14, X =
6
2
2
N
9
4
N
N
CH2
3b
4
CONH2
5
6
2
N
CH2
3b
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

Optically Active Furanoids
1225
hand, mixtures of 9- and 7-substituted regioisomers 6, 7 and 8, 9, respectively, were
obtained from adenine and 6-chloropurine. The isomers were separated by column
chromatography and their structure was assigned by NMR spectroscopy by comparison
with the published data7. 6-Mercaptopurine gave exclusively the S-substituted product 10.
The ambiguous N-nucleophilic behaviour of adenines6,7 as well as the typical S-nucleo-
philicity of mercaptopurines6 were already reported.
6-Methoxy- and 6-ethoxypurin-9-yl derivatives 11 and 12 were prepared using 1,4-
diazabicyclo[2.2.2]octane (DABCO)–potassium carbonate reagent8 in methanol and etha-
nol, respectively. The quaternary intermediate8 13 formed in the course of this reaction
was isolated and characterized. Yields, optical activity and analytical data of products
5–12 are given in Table I.
TABLE I
Characteristic data of the compounds 5–12
Calculated/Found
Yield, %
[α]D (c 1, CHCl3)
Formula
M.w.
Compound
M.p., °C
% C
% H
% N
5
6
206–207
75
C17H21N3O5
347.1
58.76
58.59
6.10
6.25
12.10
11.92
–72.6
143–145
54
–58.2a
C18H21N5O4
371.2
58.20
58.10
5.70
5.83
18.86
18.59
7
131–133
54
C18H21N5O4
371.2
58.20
57.98
5.70
5.73
18.86
18.65
–62.3
8b
9c
10
11
12d
49–50 (dec.)
47–50 (dec.)
34–37 (dec.)
37–40 (dec.)
140–141
46
C18H19ClN4O4
390.1
55.37
55.35
4.91
5.20
14.36
14.17
–57.2
46
C18H19ClN4O4
390.1
55.37
55.37
4.91
5.02
14.36
14.12
–53.7
45
C19H22N4O5
386.2
59.04
59.30
5.74
6.00
14.50
14.35
–54.9
53
C20H24N4O5
400.2
59.97
59.70
6.04
6.27
14.00
13.78
–59.6
62
C18H20N4O4S
388.1
55.65
55.67
5.19
5.29
14.43
14.31
–60.9
a Measured at c 0.5. b Calculated: 8.96% Cl, found: 8.71% Cl. c Calculated: 8.96% Cl, found: 9.02% Cl.
d Calculated: 8.24% S, found: 8.01% S.
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1226
Werfeli, Voltrova, Prutianov, Kuthan:
The success in preparation of the above mentioned compounds prompted us to inves-
tigate the reaction of 3-chloromethyl derivative 3 with nicotinamide to obtain corres-
ponding NAD model. Such types of compounds have been widely investigated9–11
especially in connection with general mechanistic problems of enzymatic reactions. As
expected, 3-carbamoyl-1-[5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methyl-3-
furylmethyl]pyridinium chloride (14) was isolated in 70% yield as a stable crystalline
substance.
NAD models are usually converted to the corresponding NADH models by the di-
thionite reduction12. We attempted to perform the conversion with the quaternary salt 14
and thus 1-[5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methyl-3-furylmethyl]-
1,4-dihydropyridine-3-carboxamide (15) was prepared as strongly hygroscopic sub-
stance which had to be stored at low temperature under nitrogen. Nevertheless, the
reduction ability of the optically active NADH model was verified.
A number of optically active NADH models has been found to reduce prochiral sub-
strates to optically active products in variable enantiomeric excesses (e.e.) and different
stereochemical interaction models have been proposed11; it is thus only a minimum
possible to predict considering a priori the molecular structure of our NADH model 15.
Reductive ability and enantioselectivity of 1,4-dihydropyridine derivative 15 were
verified by one of the standard procedures based on the reaction with ethyl phenyl-
glyoxylate catalyzed with magnesium perchlorate. The reaction rate was monitored by
decrease of the absorption maximum at 352 nm corresponding to 1,4-dihydropyridine
chromophore. Interconversion of the components proceeded in acetonitrile at 22 °C and
was completed after 4 h. The isolated ethyl mandelate was slighty optically active ex-
hibiting only ca 2% e.e. of its (R)-(–)-enantiomer. The low e.e. value conforms to a
considerable distance between the chiral and reaction sites in the molecule 15. On the
other hand, the fact that the asymmetric induction has been really observed for such a
long range effect within the molecule 15 might be surprising. However, any error was
excluded by repeated experiments.
Molecular structures of all studied compounds are confirmed by assignments of their
1H and 13C NMR spectra (Tables II and III), where signals typical for chiral, furan and
aza-heterocyclic moieties in the molecules of all synthesized compounds 1–15 (proton
signals) and pyrimidine and purine nucleosides 5–12 (carbon signals) can be easily
recognized. Thus, the chiral part exhibits more or less developed ABCMX proton sys-
tem characterized by no interaction between H-1′ and H-2′ (the proton at the position
1′ forms in all cases where distinguished clear singlet) and thus H-2′ signal is doublet
with coupling constant J(2′,3′) between 6.0 and 6.6 Hz. No coupling interaction is
observable also in the case of H-4′R and H-3′. The signal of H-3′ thus became simple
dd, as well as one of H-4′S. The value of spin–spin coupling constant J(3′,4′S) ranges
from 2.9 to 3.6 Hz (Table II).
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

Optically Active Furanoids
1227
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1228
Werfeli, Voltrova, Prutianov, Kuthan:
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

Optically Active Furanoids
1229
EXPERIMENTAL
Temperature data are uncorrected and were determined on a Boetius block. NMR spectra (δ, ppm and
J, Hz) were measured in deuteriochloroform (unless stated otherwise) using TMS as internal standard
on a GEMINI 300 instrument at 297 K. IR spectra (ν, cm–1) were recorded on a Bruker IFS 88 spec-
trometer. TLC was performed using SILUFOL UV254 plates (Kavalier, Czech Republic), HPLC
(methanol–water 9 : 1) on an instrument LCP 4000 (Ecom, Czech Republic) with the column Nucle-
osil 120 (C18, 5 µm; Macherey–Nagel, Germany). Optical rotation data were measured on a JASCO
DIP-370 polarimeter at the temperature 20 °C.
Ethyl 5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methyl-3-furoate (1) was prepared accord-
1
ing to the described procedure3. Its H NMR spectrum is given in Table II.
TABLE III
13C NMR spectra of compounds 5–12
Carbon
5
6
7
8
9
10
11
12
2a
3a
4a
5a
1′
151.18
115.65
109.90
150.67
84.15
81.73
80.26
73.26
113.34
25.46
27.05
12.30
44.03
157.37
166.60
95.60
145.03
–
152.22
115.37
109.74
151.43
84.35
81.88
80.44
73.54
113.61
25.66
27.21
12.47
38.99
152.07
114.09
109.70
151.51
84.27
81.79
80.35
73.49
113.58
25.59
27.15
12.55
45.09
152.03
114.27
108.87
151.19
84.24
81.75
80.34
73.55
113.67
25.58
27.14
12.60
43.13
153.28
143.69
123.13
162.75
149.11
–
151.36
114.47
109.32
151.37
84.10
81.62
80.18
73.33
113.40
25.42
26.98
12.32
39.51
151.63
151.54
132.06
152.75
145.40
–
151.08
116.21
110.88
150.25
84.41
81.98
80.54
73.49
113.51
25.72
27.26
12.62
24.37
152.60
115.27
109.72
151.25
84.20
81.90
80.48
73.39
113.60
25.76
27.22
12.60
39.17
152.60
115.60
109.68
151.22
84.47
2′
81.89
3′
80.56
4′
73.46
5′
113.57
25.69
6′
6′′
Me-2a
3b
2
27.44
12.52
39.25
154.37
153.80
152.12
152.86
152.87
151.15
122.04
161.51
141.96
a
a
a
a
4
a
a
5
121.05
155.12
142.17
–
120.23
156.60
140.43
–
122.21
161.77
141.20
6
8
142.00
–
Other
–
54.80
(CH3)
63.80
(CH2),
15.18
(CH3)
a
Signal not observed.
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1230
Werfeli, Voltrova, Prutianov, Kuthan:
3-Hydroxymethyl-5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methylfuran (2)
The reported procedure3 was modified in the following manner: A solution of ethyl ester 1 (9.5 g, 32 mmol)
in anhydrous ether (100 ml) was added dropwise to a suspension of lithium aluminium hydride (2.0 g,
53 mmol) in the same solvent (50 ml). The reaction was completed in 4 h according to HPLC. The
resulting reaction mixture was decomposed with aqueous 4% NaOH (8 ml) and filtered. The filtrate
was washed with anhydrous ether, evaporated and dried to yield the alcohol 2 (7.2 g, 90%) as a
colourless oil, [α]D –81° (c 1, CHCl3), the value reported in ref.3: [α]D –71° (c 1, CHCl3). For
1
C13H18O5 (254.1) calculated: 61.39% C, 7.14% H; found: 61.36% C, 7.36% H. H NMR spectrum is
given in Table II, 13C NMR spectrum in Table III. IR spectrum (CHCl3): 3 610 (OH), 1 634 (furan
ring), 1 379 (Me2C).
3-Chloromethyl-5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methylfuran (3)
Method A. A solution of thionyl chloride (0.3 g, 2.5 mmol) in dichloromethane (5 ml) was added
dropwise to a stirred mixture of 3-hydroxymethyl derivative 2 (0.5 g, 1.9 mmol), pyridine (0.2 g, 2.5 mmol)
and dichloromethane (5 ml) in 30 min. After 1 h stirring, the reaction mixture was decomposed with
water (5 ml) under ice-cooling, the organic layer was separated and the aqueous layer was repeatedly
extracted with dichloromethane. The combined organic extracts were dried with sodium sulfate and
evaporated under reduced pressure. Yield 0.42 g (80%) of 3-chloromethyl derivative 3 as a yellowish
viscous oil, [α]D –84° (c 1, CHCl3). 1H NMR spectrum is given in Table II, 13C NMR spectrum in
Table III. IR spectrum (CHCl3): 1 691 (furan ring), 1 376 (Me2C).
Method B. A cold mixture (0 °C) of tosyl chloride (0.446 g, 5.8 mmol) and triethylamine (1.0 ml,
7.2 mmol) in dichloromethane (25 ml) was added to a solution of 3-hydroxymethyl derivative 2 (1.08 g,
4.2 mmol) in the same solvent (10 ml). The reaction mixture was worked up as shown above.Yield
0.58 g (50%) of compound 3 which exhibited the same spectral properties as above mentioned pre-
parate.
Preparation of Furanoids 5, 6, 7, 8, 9 and 10. General Procedure
The corresponding heterocyclic base (1.4 mmol) was added to a suspension of sodium hydride (55 mg,
1.4 mmol) in dimethylformamide (10 ml) and the mixture was stirred under nitrogen at 70 °C for 1 h.
Then a solution of crude 3-chloromethyl derivative 3 (720 mg, 28 mmol) in dimethylformamide (5 ml)
was added dropwise and the resulting reaction mixture was heated to 60 °C for 7 h and then filtered
while hot. The precipitate was washed with dimethylformamide and the collected filtrates were co-
distilled with toluene. The residue was extracted with chloroform and chromatographed on a silica
gel column (chloroform–methanol 9 : 1 followed by chloroform–acetone 2 : 1). The composition of
1
individual fractions was monitored using HPLC and H NMR spectra. In the case of regioisomers 6, 7
and 8, 9 the less polar products were characterized as the 9-isomers, while to the more polar ones the
7-substitution was assigned. Isolated substances were purified by crystallization from the chloroform–
ether mixture. The results are summarized in Table I. The NMR spectra are given in Tables II and III.
Preparation of Furanoids 11 and 12. General Procedure
The 6-chloro derivative 9 (390 mg, 1 mmol) was heated with DABCO (10 mg) and potassium carbo-
nate (138 mg, 1 mmol) in corresponding alcohol (2 ml) at 70 °C for 1 h. After cooling the reaction
mixture was filtered and the precipitate was washed with ether. The collected filtrates were evaporated
in vacuo and the residue was chromatographed on a silica gel column (chloroform–acetone 2 : 1).
Yields of the hygroscopic products 11 and 12 are given in Table I and their NMR spectra in Tables II
and III.
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

Optically Active Furanoids
1231
1-{9-[5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methyl-3-furylmethyl]purin-6-yl}-4-aza-1-
azoniabicyclo[2.2.2]octane chloride (13)
A mixture of the 3-chloromethyl derivative 3 (0.5 g, 1.8 mmol) and DABCO (0.4 g, 3.6 mmol) in
anhydrous dimethylformamide (15 ml) was stirred at 25 °C for 2 h. The precipitate of the compound 13
was then filtered, washed with cold DMF and dried in vacuo to give a hygroscopic substance 13 in almost
quantitative yield. 1H NMR spectrum of the DABCO moiety: 2.70 brs, 4 H; 2.81 t, 2 H, J = 6.6; 3.65 t,
2 H, J = 6.6 and 4.35 brs, 4 H (6 × CH2). Chemical shifts of other protons are given in Table II.
3-Carbamoyl-1-[5-(2,3-O-isopropylidene-β-D-erythro-furanosyl)-2-methyl-3-furylmethyl]pyridinium
chloride (14)
A solution of the 3-chloromethyl derivative 3 (0.5 g, 1.8 mmol) in dimethylformamide (15 ml) was added
to nicotinamide (0.12 g, 1 mmol) in the same solvent (5 ml) under nitrogen. After 10 days, the reac-
tion mixture exhibited no nicotinamide according to TLC (ethanol–aqueous ammonia–water 95 : 5 : 5).
The solvent was co-distilled with toluene and the residue afforded a crude product, which after thor-
ough washing with ethanol afforded white crystals of quaternary salt 14. Yield 1.053 g (70%), m.p.
218–220 °C, [α]D –53.7° (c 1, DMF). For C19H23ClN2O5 (394.9) calculated: 57.85% C, 5.88% H,
1
8.87% Cl, 7.11% N; found: 57.48% C, 5.65% H, 8.75% Cl, 7.00% N. H NMR spectrum is given in
Table II. IR spectrum (KBr): 3 388 and 3 296 (NH2), 1 700 (CONH2), 1 649 (furan ring), 1 392
(Me2C).
1-[5-(2,3-O-Isopropylidene-β-D-erythro-furanosyl)-2-methyl-3-furylmethyl]-1,4-dihydropyridine-3-
carboxamide (15)
The quaternary pyridinium salt 14 (0.1 g, 0.25 mmol) was added to a saturated and cold (0 °C)
aqueous solution of sodium bicarbonate (0.18 g, 2.2 mmol) which was saturated with nitrogen. After
5 min a saturated solution of sodium dithionite (0.24 g, 1.4 mmol) in cold water was dropwise added
and the reaction mixture became yellow. Stirring was continued for further 20 min at room tempera-
ture and then at 0 °C for 3 h. After washing with chloroform (10 ml), the aqueous phase was separ-
ated and repeatedly extracted with chloroform (15 ml). The collected organic layers were dried over
sodium sulfate, filtered and evaporated at reduced pressure at 0 °C. The yellow solid, yield 0.04 g
(45%), with m.p. 68–73 °C (dec.), [α]D –58° (c 1, CHCl3) was stored at –5 °C under nitrogen. 1H NMR
spectrum: 7.08 s, 1 H (H-2); 5.68 m, 1 H (H-6); 5.13 brs, 2 H (H2N); 3.14 m, 2 H (H-4). 13C NMR
spectrum ((CD3)2SO): 174.80 C (CONH2), 143.32 CH (C-2), 135.11 CH (C-6), 107.49 CH (C-5),
106.09 C (C-3), 28.17 CH (C-4). Other proton and carbon signals not assigned to 1,4-dihydronicotin-
amide moiety, see Table II.
Reduction of Ethyl Phenylglyoxylate with NADH Model 15
Reaction was performed in the dark under dry nitrogen at the temperature of 22 °C and monitored by
measurement of UV absorption in the region of 200 to 500 nm. Reaction products were analyzed by
1H NMR spectra. A freshly prepared solution of 1,4-dihydropyridine derivative 15 (90 mg, 0.25 mmol)
in acetonitrile (10 ml) was added to a solution of ethyl phenylglyoxylate (45 mg, 0.25 mmol) and
magnesium perchlorate (62 mg) in the same solvent (5 ml). After 4 h the absorption maximum of the
compound 15 at 352 nm completely disappeared and the reaction was stopped by addition of water
(3 ml). Acetonitrile was distilled off under reduced pressure and the residue was extracted with di-
chloromethane (20 ml). The aqueous phase was evaporated and the residue exhibited 1H NMR pat-
terns similar to those in salt 14: 9.24 s, 1 H (H-2); 8.82 d, 1 H, J = 8.6 (H-6); 8.63 d, 1 H, J = 4.4
(H-4, pyridine ring); 8.01 dd, 1 H, J = 4.4 and 8.6 (H-5); 7.69 brs (NH); 7.05 brs (NH); 6.34 s, 1 H
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1232
Werfeli, Voltrova, Prutianov, Kuthan:
(H-4, furan ring); 5.60 s, 2 H (H-3b); 4.94–3.84 m, 3 H (H-1′, H-2′ and H-3′); 4.89 m, 2 H (H-4′);
2.36 s, 3 H (Me-2a); 1.48 s, 3 H and 1.30 s, 3 H (Me2C). The organic extract was dried over mag-
nesium sulfate, filtered, evaporated, treated with chloroform and chromatographed on a short silica
gel column. All collected eluents afforded only a mixture (40 mg) of ethyl mandelate (65%) and
ethyl phenylglyoxylate (35%). The both esters were carefully separated on a silica gel column (40 g
SiO2) and gave 26 mg of ethyl mandelate as colourless oil of [α]D –2.61° (c 0.5, CHCl3), in repeated
experiment [α]D –2.80° (c 0.5, CHCl3), corresponding to 1.81% e.e. (1.95% e.e., respectively) of (R)-
(–)-enantiomer. 1H NMR spectrum: 7.25 s, 5 H (Ph); 4.15 m, 2 H (CH2); 3.51 brs, 1 H (OH); 1.16 t,
3 H (Me).
The research work was supported by the Grant No. 203/93/0320 and 203/96/0497 of the Grant
Agency of the Czech Republic. The authors are indebted to the staff of Central Laboratories at Prague
Institute of Chemical Technology for IR spectral measurement and elemental analyses.
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Collect. Czech. Chem. Commun. (Vol. 61) (1996)