The synthesis and conformation of dihydroxypiperidinyl derivates of nucleobases as novel iminosugar nucleoside analogs

Article abstract of DOI:10.1002/ejoc.201001610

An optimized method for the synthesis of an important chiral scaffold, (3S,4R,5R)-1-N-Boc-3,4-isopropylidene-3,4,5-trihydroxypiperidine, was developed. Using this intermediate, the preparation of various chiral aminodihydroxypiperidines and their transfor

Full text of DOI:10.1002/ejoc.201001610

FULL PAPER
DOI: 10.1002/ejoc.201001610
The Synthesis and Conformation of Dihydroxypiperidinyl Derivates of
Nucleobases as Novel Iminosugar Nucleoside Analogs
[a]
[a]
[a]
ˇ
Dominik Rejman,* Radek Pohl, and Martin Dracínský
Keywords: Iminosugars / Azanucleosides / Nucleosides / Azides / Nitrogen heterocycles / Conformation analysis / Piperidine
An optimized method for the synthesis of an important chiral
scaffold, (3S,4R,5R)-1-N-Boc-3,4-isopropylidene-3,4,5-trihy-
droxypiperidine, was developed. Using this intermediate, the
preparation of various chiral aminodihydroxypiperidines and
their transformation into a series of non-glycosidic, six-mem-
bered azanucleosides was accomplished. NMR conformation
analysis of the prepared piperidine azanucleosides revealed
a preference for the chair conformation, with the nucleobase
fixed in the equatorial position in all cases.
Introduction
attachment to the ring. Incorporation of N-acetylazathym-
idine 1 (Figure 1) into oligonucleotides resulted in strong
inhibition of their degradation by 3Ј-exonucleases.[1] A one-
step method for the transformation of amino acid deriva-
tives into N-azasugar nucleosides was described by Boto et
al.[2] Compound 2 was found to inhibit vaccinia virus.[3] The
The azanucleosides represent an important group of anti-
metabolites that exhibit a variety of biological effects. In
these nucleoside analogs, the furanose sugar is replaced by
a nitrogen heterocycle. Modifications of the nucleobase
have also been introduced, as well as altering its position of
Figure 1. Iminosugar nucleoside and nucleotide analogues.
isoxazolidine derivative 3 was claimed to be an efficient in-
hibitor of HIV reverse transcriptase with low levels of cyto-
toxicity.[4]
[a] Institute of Organic Chemistry and Biochemistry v.v.i.,
Academy of Sciences of the Czech Republic,
Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
Fax: +42-0220183574
To the best of our knowledge, synthesis of the first aza-
sugar nucleoside analog 4 was reported by Reist et al.[5] The
E-mail: rejman@uochb.cas.cz
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Dihydroxypiperidinyl Derivates of Nucleobases
ring nitrogen atom of this compound was acylated to pre-
Based on this short survey, it can be concluded that the
vent it from spontaneous hydrolysis. Owing to the instabil- azanucleosides have recently been receiving steady attention
ity of iminonucleosides, most of the research has been fo- and, in several cases, certain biological activities were recog-
cused on non-glycosidic or aza-C-nucleosides. Aza-C-nu- nized, as well as favorable effects on the oligonucleotide
cleosides 5 and 6 (d-immucillin-H and d-DADMe-immucil- properties upon incorporation of the respective azanucleo-
lin-H) have been shown to be potent inhibitors of human side-modified units into the chains.
purine nucleoside phosphorylase, with Ki values of 56 and
In this contribution, we present synthetic transforma-
16 pM, respectively.[6] These compounds are currently in tions leading to the formation of dihydroxypiperidinyl de-
clinical trials for the treatment of T- and B-cell cancers, as rivatives of nucleobases as a novel group of compounds. In
well as for a variety of autoimmune diseases.[7] Vanek et addition to the synthetic efforts, our aim was to investigate
ˇ
al. described a synthesis of the nonglycosidic pyrrolidine in more detail the structure of the new compounds by
nucleoside phosphonic acids 7a–e and 8a–e, but no antiviral means of conformational analyses. Finally, we wanted to
or cytostatic activity was observed.[8] The synthesis of pyr- perform basic tests to determine the biological activities of
rolidine nucleosides 9a–h has been reported by our these compounds.
group.[9–10] Although no antibacterial, antiviral, or cyto-
static activities were found, the compounds offered an ad-
ditional site for further modification of the pyrrolidine ni-
Results and Discussion
trogen atom. Therefore, we prepared a series of nucleoside
phosphonate analogs,[11] and introduced this motif success-
Chemistry
fully into an oligonucleotide.[12] The phosphonate derivative
10 was found to be a potent inhibitor of thymidine phos-
On the path to the target compounds, we wanted to first
phorylase from spontaneous SD-rat lymphoma cells, exhib- develop a synthesis of the piperidine precursor starting
iting an IC50 value of 11 nM.[13] Pedersen et al. published from an available and inexpensive starting material. Thus,
the synthesis of piperidine nucleoside analog 11, in which the synthesis of conveniently protected trihydroxypiperidine
the nucleobase was attached to the piperidine nitrogen 24 was accomplished by modifying the method developed
atom.[14] Prukala et al. reported the synthesis of the piper- by Igarashi and Ichikawa.[21] Specifically, benzyl 2,3-iso-
idine derivative of cytosine 12, where the cyclic amine was propylidene-riboside (20), prepared according to the litera-
introduced through a methylene bridge at position 5 of the ture procedure[22] from ribose (19), was used instead of 1-
cytosine, by using a Mannich-type reaction.[15] N-Methyl- benzoyl 2,3-isopropylidene-riboside (Scheme 1). The advan-
d-ribopyranuronamide nucleosides 13a–b and 14a–b were tage of using a benzyl protecting group was that a conve-
synthesized and evaluated in antiviral and cytotoxic assays, nient, one-pot, four-step conversion of the azido derivative
however, no activity was found.[16–17] Piperidine nucleoside 22 (obtained in high yield via mesyl derivative 21) into the
15 was prepared by Kim et al.,[18] and it seemed that oligo- piperidine derivative 23 was possible. In the process, the
nucleotides containing this modification exhibited a strong azido moiety of compound 22 was first reduced to an amine
hybridization with RNA counterparts, depending on the lo- (which can be isolated, if the hydrogenation is monitored
cation and number of substitutions. Furthermore, it was carefully) followed by hydrogenolytic removal of the benzyl
suggested that the increase of hydrophobicity in these modi- group. The ribose ring was then opened and the formed six-
fied oligonucleotides can be advantageous for cellular up- membered iminosugar was reduced to afford the isopropyl-
take. Lonkar et al. incorporated the piperidine nucleoside idenepiperidine derivative 23. Using a standard procedure
analog 16 into the PNA mixmer, and these PNAs formed (Boc2O, NaHCO3, H2O, EtOH), compound 23 was con-
stable PNA:DNA complexes.[19] Synthesis of the piperidin- verted into the Boc derivative 24 in an excellent overall yield
yl- and hydroxypiperidinyl derivatives of nucleobases 17a–c of 74%.
and 18a–c was recently described by our group. On testing,
All attempts to introduce the nucleobase, either by sub-
none of these compounds exhibited either antibacterial or stitution of the free hydroxyl group of product 24 using a
cytostatic activity.[20]
Mitsunobu reaction, or by N-alkylation of the nucleobase
Scheme 1. Synthesis of conveniently protected trihydroxypiperidine 24.
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D. Rejman et al.
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Scheme 2. Synthesis of the dihydroxypiperidinyl derivative of uracil 29.
with the tosyl derivative 25, failed. Only complex mixtures The coupling constants were essentially the same, which
containing mainly elimination products were observed (data suggested that the same configuration and conformation
not shown). The reaction of tosyl derivative 25 with sodium existed in the piperidine ring. Additional proof that the
azide afforded an unresolvable mixture of the expected configuration had been retained during the reductive amin-
azido derivative and elimination products (not fully charac- ation were obtained from the differing NMR spectra of 26b
terized) (Scheme 2). The use of lithium azide improved the and 32, whereby 26b was prepared from the azido derivative
outcome of the reaction significantly, affording 56% iso- 26a formed stereoselectively by an SN2 reaction that is
lated yield of the azido derivative 26a; subsequent catalytic known to take place through complete inversion of configu-
hydrogenation gave amino derivative 26b in 75% yield.
ration. The amine 32 was then converted into the corre-
The reaction of amine 26b with 4-nitrophenyl (3-ethoxy- sponding uracil derivative 34 in a 40% yield (over two steps)
acryloyl)carbamate (27), recently developed in our labora- via urea intermediate 33 using the reagent 27.
tory,[23] yielded the urea derivative 28, which afforded the
To obtain analogs of nucleosides resembling the natural
uracil derivative 29 on treatment with Dowex 50 (H+) in ribo configuration, we elaborated the reaction sequence de-
dioxane at 90 °C in a 66% overall yield. picted in Scheme 4. The free hydroxyl group of 24 was ben-
To avoid alkylation reactions, we evaluated a different zylated (75% yield) and the isopropylidene protecting
route for the preparation of the amino derivative. The inter- group was selectively removed by stirring with 2% trifluoro-
mediate 24 was first oxidized with Dess–Martin periodinate acetic acid (TFA) in dichloromethane at room temperature
to afford ketone 30 a 78% yield, which underwent reductive (81% yield). The reaction was followed by TLC and, after
amination with benzylamine using sodium triacetoxy- all the starting material was consumed, solid NaHCO3 was
borohydride[24] to afford the benzylamino derivative 31 immediately added to neutralize the TFA. The suspension
(Scheme 3) in 64% yield. The benzyl group was sub- was stirred until neutral pH. After filtration and evapora-
sequently removed by catalytic hydrogenation over Pd/C tion of the solvent, the deprotected compound 36 was ob-
catalyst to afford the amino derivative 32. The reductive tained by flash chromatography on silica gel. This pro-
amination proceeded with retention of configuration. The cedure could be of general use for selective removal of the
configuration of 31 was determined from the NMR spectra isopropylidene or DMTr protecting group in the presence
3
and was based on a comparison of the JH,H values of its of other acid-labile protecting groups, for example N-Boc.
piperidine ring with those of the benzyloxy derivative 36. Selective removal of the 5,6-isopropylidene group from
Scheme 3. Synthesis of the dihydroxypiperidinyl derivative of uracil 34.
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Dihydroxypiperidinyl Derivates of Nucleobases
Scheme 4. Synthesis of aminodihydroxypiperidines 39a and 39b.
1,2;5,6-diisopropylideneglucose could be also achieved
using this method (data not shown).
The cis-diol 36 reacted with thionyl chloride to provide
the intermediate 37 in almost quantitative yield. It should
be noted here that the cyclic sulfite 37 was formed as a
mixture of diastereoisomers (isomerism at the sulfur atom),
showing two spots on TLC. Compound 37, after purifica-
tion on silica gel, was treated with lithium azide in N,N-
dimethylformamide (DMF) at elevated temperature. The
Scheme 5. Synthesis of dihydroxypiperidinyl derivative of uracil 41.
unresolvable mixture of the 4- and 5-azido derivatives ob- ous ammonia, followed by Boc group removal with TFA,
tained after rapid silica gel purification, was hydrogenated afforded the desired adenine derivative 45 in 75% yield,
over palladium catalyst. The mixture of the formed re- whereas treatment of 44 with aqueous 1 m HCl at 75 °C
gioisomeric amines was protected with the trifluoroacetyl afforded the hypoxanthine derivative 46 (in the same yield).
group by reaction with ethyl trifluoroacetate in ethanol, and
The reaction of 39a with 2,5-diamino-4,6-dichloropyrim-
the 3-O-benzyl protecting group was removed by catalytic idine (47) afforded compound 48 in 76% yield (Scheme 7).
hydrogenation. The obtained compounds 38a and 38b were The reaction of 48 with diethoxymethyl acetate in DMF
easily separated by using flash chromatography on silica gel provided the chlorpurine derivative 49 in 67% yield, which
in 43 and 24% yield, respectively (calculated over four reac- was then treated with 1 m HCl at 75 °C to afford guanine
tion steps). Finally, the trifluoroacetyl protecting groups of derivative 50 in 95% yield.
38a and 38b were removed by treatment with Dowex 1 in
The reaction of aminopiperidine 39b with 4-nitrophenyl
OH– form (88 and 91% yield, respectively). All the reaction (3-ethoxyacryloyl)carbamate (27),[23] followed by cycliza-
steps proceeded in high yields and provided access to the tion and Boc group removal by heating with Dowex 50 (H+)
piperidine nitrogen-protected azasugars 39a and 39b.
in dioxane at 80 °C, and then by preparative HPLC purifi-
The reaction of aminopiperidine 39a with reagent 27[23] cation, afforded uracil derivative 52 in 58% overall yield
proceeded smoothly to afford, after flash chromatography, (Scheme 8). Adenine derivative 54 was prepared in 30%
intermediate 40 in 85% yield (Scheme 5). After cyclization overall yield by reaction of 39b with 5-amino-4,6-dichlo-
and Boc group removal by heating with Dowex 50 (H+) in ropyrimidine (42), followed by reaction with diethoxy-
dioxane at 80 °C, followed by preparative HPLC purifica- methyl acetate in DMF, treatment with concentrated aque-
tion, uracil derivative 41 was obtained in 75% yield.
ous ammonia, and Boc group removal with TFA. Guanine
Derivatives of the purine nucleobases were synthesized derivative 56 was obtained in 33% overall yield starting
using the established procedures of nucleobase as- from compound 39b by employing, first, treatment with
sembly.[25–26] Thus, the reaction of 39a with 5-amino-4,6- reagent 47, followed by diethoxymethyl acetate cyclization
dichloropyrimidine (42) afforded compound 43 in 57% and subsequently by aqueous 1 m HCl treatment.
yield (Scheme 6). Subsequent reaction with diethoxymethyl
Finally, to demonstrate the general usefulness of the imi-
acetate in DMF provided 6-chloropurine 44 in 49% yield. nosugar chemistry presented here, amines 26, 39a, and 39b
Final treatment of compound 44 with concentrated aque- were converted into the respective N-acetyl derivatives 57–
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D. Rejman et al.
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Scheme 6. Synthesis of the dihydroxypiperidinyl derivative of adenine 45 and hypoxanthine 46.
Scheme 7. Synthesis of the dihydroxypiperidinyl derivative of guanine 50.
Scheme 8. Synthesis of dihydroxypiperidinyl derivative of uracil 52, adenine 54, and guanine 56.
59, as potential inhibitors of glycosidases,[27] by reaction
with acetic anhydride followed by treatment with TFA to
remove the isopropylidene (57) or Boc (58–59) protecting
groups (Scheme 9). The N-acetyl derivative 59 could be
used as starting material for the synthesis of inhibitors of
sialidases.[28]
Biological Activity Testing
In keeping with the aims set for this work, we submitted
compounds 29, 34, 41, 45–46, 50, 52, 54, and 56–59 for
biological activity screening. However, no significant cyto-
static (L1210, HL60, HeLa S3, CCRF-CEM), antibacterial
(Enterococcus faecalis CCM 4224, Staphylococcus aureus
CCM 4223, Escherichia coli CCM 3954, Pseudomonas aeru-
ginosa CCM 3955 Bacillus subtilis, Streptococcus agalac-
tiae), or antiviral (HIV, HCV, RSV) activities of the pre-
pared compounds were observed. Further tests of the pre-
Scheme 9. Synthesis of N-acetylpiperidine azasugars 57–59.
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Dihydroxypiperidinyl Derivates of Nucleobases
pared N-acetylazasugars 57–59, considered as potential in- namely, the uracil nucleosides 41 and 52, where the pyrim-
hibitors of several glycosidases, are underway.
idine base is attached trans to a neighboring hydroxyl
group. When the H NMR spectra of these pyrimidine de-
1
rivatives were measured at higher temperature (100 °C,
[D6]DMSO), one set of sharp signals was present; at low-
temperature, the spectra (–80 °C, CD3OD) consisted of two
sets of sharp signals with different intensities. These obser-
vations indicate a slow exchange between the two conform-
ers of the nucleosides. The most important differences in
the chemical shifts between the two conformers were ob-
served for C-6, C-4Ј, H-3Ј, and H-4Ј signals (see Table 2).
Initially, we believed that the conformational change of the
six-membered piperidine ring could be responsible for the
line broadening of the signals (exchange between two
chairs, or between chair and boat conformations). However,
from the coupling pattern observed in the 1H NMR spectra
at low temperature, it became clear that both conformers
have identical chair conformations. For example, the signal
arising from the hydrogen atom H-4Ј (attached to the car-
bon atom bearing the uracil part of the molecule) appeared
as a triplet with a large coupling constant (J = 10.3 Hz),
which indicates axial positions for all three hydrogen atoms
in the 4Ј and 5Ј positions in compound 52.
Conformation Analysis of Piperidine Nucleosides
1H NMR spectra of the final azanucleosides were used
to determine the piperidine ring conformation. Structural
information is encoded in the vicinal H,H coupling con-
stants of the piperidine ring, which can be extracted from
1H NMR spectra (see Table 1). Characteristic coupling val-
ues for the axial–axial interaction (J = 10.0–12.1 Hz) could
thus be used to predict the spatial arrangement of protons
in the ring. For example, the 4Ј-proton (for numbering, see
Figure 2) is in an axial position in derivatives 41, 45, 46, 50,
54, and 56, whereas in compound 34 it occupies an equato-
rial position. We observed a preferred chair conformation,
with the nucleobase fixed in the equatorial position, for all
target azanucleosides (Figure 2).
Table 1. Vicinal coupling constants of the piperidine ring protons
(for numbering see Figure 2).
J(2Јa,3Ј) J(2Јb,3Ј) J(3Ј,4Ј) J(4Ј,5Ј) J(5Ј,6Јax) J(5Ј,6Јeq)
34[a]
41[b]
45[a]
46[a]
50[a]
52[c]
54[a]
56[a]
5.1
2.9
3.2
3.5
3.3
5.3
4.8
4.8
11.4
1.6
1.4
0.9
1.5
10.2
10.3
10.7
2.9
3.0
2.9
2.9
2.9
10.3
10.0
10.3
1.7
12.1
11.2
12.1
10.7
10.6
10.2
10.3
10.7
4.3
4.7
5.4
6.5
6.1
5.3
4.8
4.8
10.7
10.7
10.7
10.6
10.3
10.0
10.3
Table 2. Experimental 13C and 1H NMR chemical shifts of con-
formers C1 and C2 of compound 52 measured in CD3OD at
–80 °C. Experimental and calculated (B3LYP/6-311+G(d,p)/PCM)
chemical shift differences (C1–C2).
δexp(C1)
154.06
δexp(C2)
Δδexp(C1–C2) Δδcalc(C1–C2)
C-2
C-4
C-5
C-6
C-2Ј
C-3Ј
C-4Ј
H-5
152.33
167.44
100.94
151.19
51.84
66.27
79.11
5.63
1.7
–0.9
1.9
2.0
–0.7
1.8
[a] In D2O, 25–28 °C. [b] In [D6]DMSO, 60 °C. [c] In CD3OD,
–80 °C.
166.58
102.83
142.99
52.06
69.13
65.70
5.82
–8.2
0.2
2.9
–9.4
–0.4
3.6
–13.4
0.2
–15.0
0.2
H-6
7.88
7.50
0.4
0.1
H-2Јax
H-2Јeq
H-3Ј
H-4Ј
2.50
3.16
3.64
4.44
2.40
3.16
4.51
3.24
0.1
0.0
–0.9
1.2
0.2
0.0
–0.8
1.5
The results of selective 1D-NOE measurements showed
that the two conformations are rotamers around the C4Ј–
N1 bond (see Figure 3). Spatial proximity between H-6, H-
3Ј, and H-5Ј atoms was observed in one conformer, and
between the H-6 and H-4Ј atoms in the second. To further
support these findings, we optimized the geometries of the
Figure 2. Preferred conformation of the piperidine ring in target
azanucleosides.
In the 1H NMR spectra of piperidine derivatives pro- two conformers in silico at the DFT level and then calcu-
1
tected with the Boc group, all signals appeared as broad lated the H and 13C chemical shifts. The experimental and
lines; this is not surprising because it is well-known that calculated chemical shifts of the two conformers agreed
rotation around the C–N bonds in amides is restricted by very well (see Table 2).
the partial double character of this bond. The slow in-
It is interesting that the slow interconversion between the
terconversion between the two rotamers at room tempera- two conformers was observed only in uracil nucleosides 41
ture causes the broadening of NMR signals. At higher tem- and 52, for which both the uracil part and the neighboring
peratures, the rotation around the partial double bond is hydroxyl group were equatorial. We did not observe similar
faster and the NMR signals become sharper. We were sur- behavior for the purine derivatives 45, 46, 50, 54, and 56 or
prised to observe significant line broadening also in the for uracil derivative 34, where the neighboring hydroxyl
NMR spectra of some of the deprotected derivatives, group was axial. The barrier for rotation around the C4Ј–
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D. Rejman et al.
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Reagent 27 was prepared according to literature procedures,[23]
whereas 1-benzyl-2,3-isopropylidenglucose (20) was prepared ac-
cording to the procedure described by Watanabe et al.[22] TLC was
performed on silica gel pre-coated aluminum plates (Silica gel/
TLC-cards), UV 254 (Fluka), and the compounds were detected by
UV light (254 nm), by heating (detection of dimethoxytrityl group;
orange color), by spraying with 1% ethanolic solution of ninhyd-
rine (to visualize amines), or by spraying with 1% solution of 4-(4-
nitrobenzyl)pyridine in ethanol followed by heating and treating
with gaseous ammonia (blue color: detection of alkylating agents,
e.g., the tosyl derivatives). Preparative column chromatography was
carried out on silica gel (40–60 μm; Fluka), and elution was per-
formed at the flow rate of 40 mL/min. Analytical RP HPLC was
performed with an LC5000 Liquid Chromatograph (INGOS-PI-
KRON, Czech Rep.) using a Luna C18 (2) column (4.6ϫ150 mm)
at a flow rate of 1 mL/min with a gradient elution of methanol in
0.1 m TEAA, pH 7.5 (A = 0.1 m TEAB; B = 0.1 m TEAB in 50%
aqueous methanol; C = methanol). Preparative RP HPLC was per-
formed with an LC5000 Liquid Chromatograph (INGOS-PI-
KRON, CR) using a Luna C18 (2) column (250ϫ21.2 mm) at the
flow rate of 10 mL/min by a gradient elution of methanol in 0.1 m
TEAB, pH 7.5 (A = 0.1 m TEAB; B = 0.1 m TEAB in 50% aqueous
methanol; C = methanol). All final compounds were lyophilized
from water. Melting points were determined wirth a Stuart SMP
model 30 instrument. Optical rotation values were measured with
an AUTOPOL IV polarimeter (Rudolph Research Analytical,
USA) at the sodium D line at 20 °C. Mass spectra were recorded
with a ZAB-EQ (VG Analytical) instrument, using FAB (ionization
with Xe, accelerating voltage 8 kV; glycerol and thioglycerol were
used as matrices) and with an LTQ Orbitrap XL (Thermo Fisher
Scientific) instrument using ESI ionization. NMR spectra were
measured with Bruker AVANCE 400 (1H at 400 MHz, 13C at
100.6 MHz), Bruker AVANCE 500 (1H at 500 MHz, 13C at
125.7 MHz), and/or Bruker AVANCE 600 (1H at 600.1 MHz, 13C
Figure 3. Conformer C1 (left) and C2 (right) of compound 52.
Geometries were optimized at the B3LYP/6-31+G(d,p)/PCM level.
Experimentally observed NOE contacts are shown. Hydrogen
atoms not important for the conformational analysis were omitted
for clarity.
N1 bond is probably higher in the uracil derivatives because
of higher steric demands of the six-membered uracil ring in
comparison with the purine molecule (see Figure 4).
Figure 4. Proposed transition states for rotamer interconversion of
purine (left) and uracil (right) nucleosides.
Conclusions
This work is a new contribution to the chemistry of aza-
sugars and the azasugar nucleosides. We present convenient
synthetic methods for the preparation of the protected chi-
ral aminodihydroxypiperidines 26b, 32, 39a, and 39b, which
are useful intermediates for broader synthetic exploitation, at 150.9 MHz) spectrometers. Chemical shifts (ppm, δ scale) were
referenced to TMS or 1,4-dioxane [δ(1H) = 3.75 ppm, δ(13C) =
and subsequent utilization of these chiral scaffolds in the
synthesis of a series of novel azanucleosides 29, 34, 41, 45,
46, 52, 54, and 56. Knowledge gained from developing the
synthetic transformations may be of general usefulness for
69.3 ppm; when D2O was used as solvent] as internal standard, or
to residual solvent signal [(D6)DMSO: δ(1H) = 2.50 ppm, δ(13C) =
39.7 ppm; CD3OD: δ(1H) = 3.31 ppm, δ(13C) = 49.0 ppm]; coupling
constants (J) are given in Hz. Complete assignment of protons and
carbons was achieved by analysis of the correlated homonuclear
further work in areas related to modified nucleosides. The
conformations of the novel compounds were evaluated by
using NMR and computational approaches, and we were
able to determine a preference for the chair conformations
for the piperidine ring in the compounds investigated. Pre-
pared piperidine azanucleosides 29, 34, 41, 45, 46, 52, 54,
and 56 offer further possibilities for derivatization at the
piperidine nitrogen atom, thereby providing the chance to
prepare yet more types of structurally diverse compounds,
for example, phosphonate piperidine nucleotides, and, con-
sequently, extend the range of potentially available biolo-
gically active compounds. Such possibilities make these
compounds interesting, although no significant biological
2D-COSY and heteronuclear 1H-13C HSQC and 1H-13C HMBC
spectra. Relative configuration was checked using DPFGSE-NOE
and 2D-ROESY techniques. The nucleobase atom numbering was
also adopted for use in the case of linear intermediates:
1-O-Benzyl-2,3-O-isopropylidene-5-O-(p-tolylsulfonyl)-β-D-ribo-
furanose (21):[29] Tosyl chloride (19 g, 100 mmol) was added to a
solution of 1-O-benzyl-2,3-O-isopropylidene-β-d-ribofuranose
effects have been observed so far. Tests on the prepared N- (prepared according to Watanabe et al.;[22] 19 g, 67.78 mmol) in
pyridine (400 mL). The reaction mixture was stirred at r.t. for 30 d.
Water (3 mL) was added and the mixture was concentrated in
vacuo. The residue was co-evaporated with toluene (2ϫ100 mL)
and the desired product was obtained by flash chromatography on
silica gel using a linear gradient of ethyl acetate in toluene; yield
acetylazasugars 57–59 as potential inhibitors of certain gly-
cosidases, are underway.
Experimental Section
Compounds 20, 23, and 24 have been reported in literature[21] but
were not fully characterized, therefore, we provide full characteriza-
tion here. Unless stated otherwise, all solvents were anhydrous.
1
94% (27.59 g, 63.5 mmol). H NMR (500.0 MHz, CDCl3, 28 °C):
4
δ = 1.28, 1.44 [2ϫq, J = 0.8 Hz, 2ϫ3 H, (CH3)2C], 2.42 (s, 3 H,
CH3-Ts), 4.03 (dd, Jgem = 10.0, J5b,4 = 6.8 Hz, 1 H, 5b-H), 4.06
(dd, Jgem = 10.0, J5a,4 = 7.7 Hz, 1 H, 5a-H), 4.36 (ddd, J4,5 = 7.7,
2178
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2172–2187

Dihydroxypiperidinyl Derivates of Nucleobases
6.8, J4,3 = 0.7 Hz, 1 H, 4-H), 4.39, 4.58 (2ϫd, Jgem = 11.8 Hz,
2ϫ1 H, CH2Ph), 4.62 (d, J2,3 = 6.0 Hz, 1 H, 2-H), 4.63 (br. d, J3,2
17.9 mmol), NaHCO3 (8.4 g, 100 mmol), and Boc2O (6 g,
20 mmol) in 50% aqueous ethanol (200 mL) was stirred at r.t. for
= 6.0 Hz, 1 H, 3-H), 5.12 (s, 1 H, 1-H), 7.25 (m, 2 H, o-Bn-H), 1 h. The mixture was filtered, concentrated in vacuo, and the de-
7.27–7.36 (m, 5 H, m,p-Bn-H, m-Ts-H), 7.76 (m, 2 H, o-Ts-H) ppm. sired product was obtained by flash chromatography on silica gel
13C NMR (125.7 MHz, CDCl3, 28 °C): δ = 21.57 (CH3-Ts), 24.72, using a linear gradient of ethyl acetate in toluene, followed by a
26.23 [(CH3)2C], 69.27 (CH2-5, CH2Ph), 81.34 (CH-3), 83.71 (CH- linear gradient of ethanol in ethyl acetate; yield 85 % (4.13 g,
4), 84.93 (CH-2), 107.24 (CH-1), 112.64 [C(CH3)2], 127.88 (CH-o- 15.11 mmol); white crystals; m.p. 88.5–89.5 °C. 1H NMR
Bn, CH-o-Ts), 128.00 (CH-p-Bn), 128.43 (CH-m-Ts), 129.86 (CH-
mBn), 132.55 (C-i-Ts), 136.66 (C-i-Bn), 145.00 (C-pTs) ppm. IR:
(500.0 MHz, [D6]DMSO, 28 °C; a mixture of amidic rotamers ca.
4:3): δ = 1.25, 1.33 [2ϫs, 2 ϫ6 H, (CH3)2C], 1.38 {br. s, 18 H,
[(CH3)3C]}, 3.03 (br. d, Jgem = 14.5 Hz, 1 H, 2b-H), 3.05–3.16 (m,
ν
max
(CHCl3), 3090 (w), 3067 (w), 1599 (m), 1497 (m), 1455 (m),
˜
1400 (m), 1383 (s), 1373 (vs), 1308 (m), 1292 (m), 1190 (vs), 1177 3 H, 2ϫH-6b, 2b-H), 3.17–3.25 (m, 2 H, 6a-H), 3.48, 3.55 (2ϫbr.
(vs), 1161 (s), 1096 (vs), 1079 (vs), 1059 (s), 1027 (m, sh), 1018 (s),
984 (vs), 920 (m), 815 (s), 399 (s), 577 (m), 555 (s), 533 (m), 518
(m) cm–1. HRMS-FAB: calcd. for C22H27O7S [M + H]+ 435.14775;
found 435.14661.
d, Jgem = 14.5 Hz, 2ϫ1 H, 2a-H), 3.77, 3.88 (2ϫdt, J5,6 = 11.2,
J5,4 = J3,OH = 5.9 Hz, 2ϫ1 H, 5-H), 4.22–4.31 (m, 4 H, 4,3-H),
5.11 (d, JOH,5 = 5.9 Hz, 1 H, OH-5) ppm. 13C NMR (150.9 MHz,
[D6]DMSO, 28 °C; a mixture of amidic rotamers ca. 4:3): δ = 24.84,
26.68 [(CH3)2C], 28.31 [(CH3)3C], 41.46, 42.83 (CH2-2), 43.20,
43.74 (CH2-6), 64.35 (CH-5), 72.52 (CH-3), 74.20 (CH-4), 78.70
5-Azido-1-O-benzyl-5-deoxy-2,3-O-isopropylidene-β-D-ribofuranose
(22): Sodium azide (12 g, 175 mmol) was added to a solution of 21
(15.21 g, 35 mmol) in DMF (200 mL), and the reaction mixture
was stirred at 80 °C overnight. The mixture was filtered through
Celite, the filtrate was concentrated in vacuo, and the desired prod-
uct was obtained by flash chromatography of the residue on silica
gel using a linear gradient of ethyl acetate in toluene; yield 96%
[C(CH ) ], 108.12 [C(CH ) ], 154.69 (CO) ppm. IR (CHCl ): ν
˜
max
3 3
3 2
3
= 3573 (w), 3445 (w), 2983 (s), 1688 (vs, br.), 1473 (m), 1465 (m,
sh), 1456 (s), 1413 (vs), 1394 (s), 1384 (s), 1378 (s), 1368 (s), 1260
(s, sh), 1248 (s), 1163 (vs), 1139 (s), 1075 (s), 1044 (s), 1001 (s), 855
(m), 514 (m) cm–1. HRMS-FAB: calcd. for C13H24O5N [M + H]+
274.1655; found 274.1649.
1
(10.26 g, 33.59 mmol). H NMR (600.1 MHz, CDCl3, 28 °C): δ =
1.31, 1.48 [2ϫquint, 4J = 0.6, 5J = 0.6 Hz, 2ϫ3 H, (CH3)2C], 3.30
(dd, Jgem = 12.4, J5b,4 = 6.8 Hz, 1 H, 5b-H), 3.49 (dd, Jgem = 12.4,
J5a,4 = 7.9 Hz, 1 H, 5a-H), 4.34 (dddq, J4,5 = 7.9, 6.8, J4,3 = 1.2,
5J = 0.6 Hz, 1 H, 4-H), 4.50 (d, Jgem = 11.7 Hz, 1 H, CHaHbPh),
(3R,4S,5S)-1-(tert-Butoxycarbonyl)-4,5-O-isopropylidene-3-O-(p-tol-
ylsulfonyl)-3,4,5-trihydroxypiperidine (25): Tosyl chloride (7.5 g,
39.14 mmol) was added to a solution of 24 (7.13 g, 26.09 mmol),
triethylamine (11 mL, 78.27 mmol), and 4-(dimethylamino)pyr-
idine (DMAP; 0.32 g, 2.6 mmol) in CH2Cl2 (260 mL), and the reac-
tion mixture was stirred at r.t. overnight. The mixture was washed
with saturated aq. NaHCO3, and the title product was obtained by
flash chromatography on silica gel using linear gradient of ethyl
acetate in toluene; yield 93% (10.38 g, 24.27 mmol); white solid;
5
4.62 (ddq, J3,2 = 6.0, J3,4 = 1.2, J = 0.6 Hz, 1 H, 3-H), 4.70 (dd,
J2,3 = 6.0 Hz, 1 H, 2-H), 4.75 (d, Jgem = 11.7 Hz, 1 H, CHaHbPh),
5.19 (s, 1 H, 1-H), 7.30 (m, 1 H, p-Ph-H), 7.32 (m, 2 H, o-Ph-H),
7.35 (m, 2 H, m-Ph-H) ppm. 13C NMR (150.9 MHz, CDCl3,
28 °C): δ = 24.83, 26.34 [(CH3)2C], 53.64 (CH2-5), 69.49 (CH2Ph),
82.06 (CH-3), 85.21 (CH-2), 85.55 (CH-4), 107.63 (CH-1), 112.68
[C(CH3)2], 127.96 (CH-p-Ph), 128.03 (CH-o-Ph), 128.50 (CH-
1
m.p. 133–135 °C. H NMR (500.0 MHz, [D6]DMSO, 100 °C): δ =
1.25, 1.36 [2ϫs, 2 ϫ3 H, (CH3)2C], 1.39 {s, 9 H, [(CH3)3C]}, 2.44
(s, 3 H, CH3-Ts), 3.31 (br. dd, Jgem = 14.3, J6b,5 = 3.0 Hz, 1 H, 6b-
H), 3.33 (m, 2 H, 2-H), 3.50 (dd, Jgem = 14.3, J6a,5 = 3.7 Hz, 1 H,
mPh), 136.79 (C-i-Ph) ppm. IR (CHCl ): ν
= 3091 (vw), 3068
˜
3
max
(w), 3030 (w), 2107 (vs), 1607 (vw), 1588 (vw), 1498 (w), 1456 (m),
1384 (m), 1376 (m), 1358 (m), 1307 (m, sh), 1273 (s), 1160 (m),
1099 (s), 1077 (s), 1043 (s), 1029 (m), 1011 (m), 915 (w), 699 (m),
551 (w), 514 (w) cm–1. HRMS-FAB: calcd. for C15H20O4N3 [M +
H]+ 306.1454; found 306.1462.
6a-H), 4.33 (m, 1 H, 5-H), 4.35 (m, 1 H, 4-H), 4.81 (ddd, J3,2
=
8.6, 6.7, J3,4 = 3.0 Hz, 1 H, 3-H), 7.48 (m, 2 H, m-Ts-H), 7.82 (m,
2 H, o-Ts-H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ
= 20.63 (CH3-Ts), 24.40, 25.92 [(CH3)2C], 27.70 [(CH3)3C], 40.93
(CH2-2), 41.92 (CH2-6), 71.48 (CH-4), 72.00 (CH-5), 74.00 (CH-
3), 78.95 [C(CH3)3], 108.78 [C(CH3)2], 127.11 (CH-o-Ts), 129.72
(CH-m-Ts), 133.39 (C-i-Ts), 144.67 (C-pTs), 153.79 (CO) ppm. IR
(3S,4R,5R)-3,4-O-Isopropylidene-3,4,5-trihydroxypiperidine (23): A
solution of 22 (10.26 g, 33.58 mmol) in ethanol (400 mL) was hy-
drogenated in the presence of Pd/C catalyst (1 g) overnight. The
catalyst was filtered off through Celite and the filtrate was evapo-
rated to afford the desired product in a 96 % yield (6.12 g,
32.36 mmol) as a white solid. M.p. 96–97 °C. 1 H NMR
(600.1 MHz, [D6]DMSO, 28 °C): δ = 1.25, 1.42 [2 ϫs, 2 ϫ3 H,
(CH3)2C], 2.37 (dd, Jgem = 12.6, J2b,3 = 8.3 Hz, 1 H, 2b-H), 2.43
(CHCl ): ν
= 2983 (s), 1693 (vs, br.), 1599 (m), 1495 (m), 1475
˜
3
max
(m), 1456 (s), 1414 (vs), 1395 (s), 1384 (s), 1376 (vs, sh), 1368 (vs),
1309 (m), 1292 (m), 1260 (s), 1246 (s), 1190 (vs), 1178 (vs), 1163
(vs, sh), 1121 (m, sh), 1057 (m), 1035 (w), 1020 (m), 1001 (s), 988
(s), 855 (s), 815 (s), 704 (w), 571 (m), 554 (s), 513 (m) cm–1. HRMS-
ESI: calcd. for C20H29O7NNaS [M + Na]+ 450.15569; found
450.15567.
(dd, Jgem = 11.8, J6b,5 = 10.3 Hz, 1 H, 6b-H), 2.64 (dddd, Jgem
=
11.8, J6a,5 = 5.1, J6a,2a = 1.0, J6a,4 = 0.7 Hz, 1 H, 6a-H), 2.79 (ddd,
Jgem = 12.6, J2a,3 = 6.2, J2a,6a = 1.0 Hz, 1 H, 2a-H), 3.62 (ddd, J5,6
= 10.3, 5.1, J5,4 = 3.8 Hz, 1 H, 5-H), 3.99 (ddd, J3,2 = 8.3, 6.2, J3,4
= 4.9 Hz, 1 H, 3-H), 4.20 (dd, J4,5 = 4.9, J4,3 = 3.8 Hz, 1 H, 4-
H) ppm. 13C NMR (150.9 MHz, [D6]DMSO, 28 °C): δ = 26.51,
28.32 [(CH3)2C], 46.89 (CH2-6), 47.23 (CH2-2), 66.35 (CH-5), 72.86
(3S,4R,5S)-5-Azido-1-(tert-butoxycarbonyl)-3,4-O-isopropylidene-
3,4-dihydroxypiperidine (26a): A mixture of compound 25 (8.58 g,
20.07 mmol) and lithium azide (2.95 g, 60 mmol) in DMF (200 mL)
was stirred at 120 °C for 3 d. The solvent was removed in vacuo
and the residue was applied onto a column of silica gel. Using a
linear gradient of ethyl acetate in toluene, the desired product was
(CH-3), 75.78 (CH-4), 108.30 [C(CH ) ] ppm. IR (KBr): ν
=
˜
3 2
max
1
3427 (v br., sh), 3266 (m), 3090 (m, v br.), 2987 (s), 2937 (s), 2869
(s), 2836 (m), 1456 (m), 1382 (s), 1371 (s), 1339 (w), 1245 (s), 1219
(s), 1171 (m), 1093 (s), 1076 (vs), 1045 (vs), 1003 (m), 858 (s), 700
(w), 514 (m) cm–1. HRMS-FAB: calcd. for C8H16O3N [M + H]+
174.11247; found 174.11245.
obtained in 56% yield (3.35 g, 11.22 mmol) as a yellowish oil. H
NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.32, 1.42 [2ϫs, 2 ϫ3
H, (CH3)2C], 1.44 {s, 9 H, [(CH3)3C]}, 3.10 (dd, Jgem = 13.4, J6b,5
= 7.9 Hz, 1 H, 6b-H), 3.34 (dd, Jgem = 14.5, J2b,3 = 3.5 Hz, 1 H,
2b-H), 3.64 (ddd, Jgem = 13.4, J6a,5 = 4.1, J6a,2a = 0.9 Hz, 1 H, 6a-
H), 3.76 (ddd, J5,6 = 7.9, 4.1, J5,4 = 5.7 Hz, 1 H, 5-H), 3.85 (ddd,
(3S,4R,5R)-1-(tert-Butoxycarbonyl)-3,4-O-isopropylidene-3,4,5-tri-
hydroxypiperidine (24): A mixture of compound 23 (3.1 g,
Jgem = 14.5, J2a,3 = 3.5, J2a,6a = 0.9 Hz, 1 H, 2a-H), 4.12 (t, J4,3
=
Eur. J. Org. Chem. 2011, 2172–2187
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2179

D. Rejman et al.
FULL PAPER
J4,5 = 5.7 Hz, 1 H, 4-H), 4.29 (dt, J3,4 = 5.7, J3,2 = 3.5 Hz, 1 H, 3- changer. The resin was washed consecutively with 50% aq. ethanol
H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ = 25.08,
(200 mL) and water (100 mL), and the title compound was eluted
27.09 [(CH3)2C], 27.73 [(CH3)3C], 41.97 (CH2-6), 42.41 (CH2-2),
with 3% aq. ammonia. The pure compound 29 was then obtained
58.56 (CH-5), 71.47 (CH-3), 74.51 (CH-4), 79.06 [C(CH3)3], 108.47 by preparative reverse-phase HPLC; yield 94% (0.24 g, 0.99 mmol);
[C(CH ) ], 154.18 (CO) ppm. IR (CHCl ): ν
= 2985 (s), 2109 white amorphous solid; [α]20 = +96 (c = 0.329, H2O). 1H NMR
˜
max
3 2
3
(vs), 1691 (vs, br.), 1477 (s), 1456 (s), 1413 (vs), 1394 (s), 1385 (vs),
1375 (vs), 1368 (vs), 1247 (vs), 1160 (vs), 1055 (s, sh), 1039 (m),
857 (m, sh), 556 (w), 514 (w, sh) cm–1. HRMS-ESI: calcd. for
C13H22O4N4Na [M + Na]+ 321.15333; found 321.15333.
(500.0 MHz, [D6]DMSO, 60 °C): δ = 2.56 (br. t, Jgem = J6Јb,5Ј =
11.9 Hz, 1 H, 6Јb-H), 2.59 (dd, Jgem = 13.9, J2Јb,3Ј = 1.6 Hz, 1 H,
2Јb-H), 2.81–2.87 (m, 2 H, 2Јa, 6Јa-H), 3.76 (m, 1 H, 3Ј-H), 3.79
(dd, J4Ј,5Ј = 10.7, J4Ј,3Ј = 3.0 Hz, 1 H, 4Ј-H), 4.40 (ddd, J5Ј,6Јb
=
11.9, J5Ј,4Ј = 10.7, J5Ј,6Јa = 4.7 Hz, 1 H, 5Ј-H), 4.48 (br. s, 1 H, OH),
4.58 (br. s, 1 H, OH), 5.51 (d, J5,6 = 7.9 Hz, 1 H, 5-H), 7.62 (d,
J6,5 = 8.0 Hz, 1 H, 6-H) ppm. 13C NMR (125.7 MHz, [D6]DMSO,
100 °C): δ = 48.05 (CH2-6Ј), 50.30 (CH2-2Ј), 56.79 (CH-5Ј), 69.26
(CH-3Ј), 69.68 (CH-4Ј), 100.66 (CH-5), 142.96 (CH-6), 151.49 (C-
(3S,4R,5S)-5-Amino-1-(tert-butoxycarbonyl)-3,4-O-isopropylidene-
3,4-dihydroxypiperidine (26b): Compound 26a (3.35 g, 11.22 mmol)
in ethanol (150 mL) was hydrogenated using Pd/C catalyst (0.4 g)
overnight. The catalyst was filtered off through Celite and the sol-
vent was removed in vacuo. The title compound was obtained by
flash chromatography on silica gel using a linear gradient of etha-
nol in chloroform, as a colorless oil; yield 75% (2.3 g, 8.45 mmol).
1H NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.29, 1.37 [2ϫq,
4J = 0.7 Hz, 2ϫ3 H, (CH3)2C], 1.42 {s, 9 H, [(CH3)3C]}, 2.88 (dd,
Jgem = 12.7, J6b,5 = 7.2 Hz, 1 H, 6b-H), 3.95 (ddd, J5,6 = 7.2, 3.8,
J5,4 = 5.3 Hz, 1 H, 5-H), 3.44 (dd, Jgem = 14.1, J2b,3 = 3.8 Hz, 1 H,
2b-H), 3.46 (ddd, Jgem = 12.7, J6a,5 = 4.0, J6a,2a = 0.9 Hz, 1 H, 6a-
H), 3.67 (dd, Jgem = 14.1, J2a,3 = 3.8 Hz, 1 H, 2a-H), 3.86 (dd, J4,3
= 6.4, J4,5 = 5.3 Hz, 1 H, 4-H), 4.21 (dt, J3,4 = 6.4, J3,2 = 3.8 Hz,
1 H, 3-H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ =
25.03, 27.15 [(CH3)2C], 27.86 [(CH3)3C], 42.41 (CH2-2), 45.36
(CH2-6), 49.09 (CH-5), 71.37 (CH-3), 77.51 (CH-4), 78.29 [C(CH3)
3], 107.49 [C(CH3)2], 154.48 (CO) ppm. HRMS-ESI: calcd. for
C13H25O4N2 [M + H]+ 273.18088; found 273.18089.
2), 163.11 (C-4) ppm. IR (KBr): ν
= 3480 (w, br., sh), 3288 (m,
˜
max
v br.), 3190 (br. m, sh), 2901 (m, v br.), 1686 (vs, br.), 1625 (m, sh),
1463 (m), 1385 (m), 1257 (m), 1101 (m), 1066 (m), 990 (w, br.), 811
(w), 766 (w), 719 (w) cm–1. HRMS-ESI: calcd. for C9H14O4N3 [M
+ H]+ 228.0979; found 228.0978.
(4S,5S)-1-(tert-Butoxycarbonyl)-4,5-O-isopropylidene-4,5-di-
hydroxypiperidin-3-one (30): Dess–Martin periodinate (12.1 g,
28.5 mmol) was added to a solution of 24 (5.18 g, 19 mmol) in
CH2Cl2 (200 mL) at r.t. The reaction mixture was stirred for 2 h
then washed with sat. NaHCO3. The title compound was purified
by chromatography on silica gel using a linear gradient of ethyl
acetate in toluene; yield 78% (4 g, 14.74 mmol); thick yellowish oil
that solidified on standing in a refrigerator. 1H NMR (500.0 MHz,
[D6]DMSO, 100 °C): δ = 1.32, 1.33 [2ϫs, 2 ϫ3 H, (CH3)2C], 1.43
{s, 9 H, [(CH3)3C]}, 3.52 (dd, Jgem = 14.6, J6b,5 = 3.2 Hz, 1 H, 6b-
H), 3.82 (dd, Jgem = 17.4, J2b,4 = 0.7 Hz, 1 H, 2b-H), 3.88 (ddd,
Jgem = 14.6, J6a,5 = 3.6, J6a,2a = 1.7 Hz, 1 H, 6a-H), 4.21 (ddd, Jgem
= 17.4, J2a,6a = 1.7, J2a,4 = 0.7 Hz, 1 H, 2a-H), 4.46 (dt, J4,5 = 7.5,
J4,2 = 0.7 Hz, 1 H, 4-H), 4.58 (ddd, J5,4 = 6.8, J5,6 = 3.6, 3.2 Hz, 1
H, 5-H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ =
25.01, 26.40 [(CH3)2C], 27.70 [(CH3)3C], 44.21 (CH2-6), 52.80
(CH2-2), 74.55 (CH-5), 76.57 (CH-4), 79.36 [C(CH3)3], 109.72
(3S,4R,5S)-5-[3-(3-Ethoxyacryloyl)ureido]-1-(tert-butoxycarbonyl)-
3,4-O-isopropylidene-3,4-dihydroxypiperidine (28): 2-Nitrophenyl
(3-ethoxyacryloyl)carbamate (0.56 g, 2 mmol) was added to a solu-
tion of amine 26b (0.5 g, 1.84 mmol) in dioxane (20 mL). The reac-
tion mixture was stirred at r.t. overnight, then the solvent was re-
moved in vacuo and the title compound was purified by
chromatography on silica gel using a linear gradient of ethyl acetate
in toluene; yield 70 % (0.55 g, 1.29 mmol); yellowish foam. 1H
NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.28 (t, Jvic = 7.0 Hz,
[C(CH ) ], 153.78 (CO), 202.07 (C-3) ppm. IR ([D ]DMSO): ν
˜
max
3 2
6
= 2981 (m), 2935 (m), 1737 (m), 1694 (vs), 1478 (w), 1456 (m),
1416 (m), 1393 (m), 1383 (m), 1372 (m, sh), 1368 (s), 1265 (m, sh),
1247 (s), 1158 (vs), 1122 (m), 1085 (m) cm–1. HRMS-ESI: calcd.
for C13H21O5NNa [M + Na]+ 294.1312; found 294.1309.
4
3 H, CH3CH2O), 1.30, 1.42 [2ϫs, J = 0.6 Hz, 2ϫ3 H, (CH3)2C],
1.43 [s, 9 H, (CH3)3C], 3.15 (dd, Jgem = 13.1, J6Јb,5Ј = 7.3 Hz, 1 H,
6Јb-H), 3.56 (dd, Jgem = 14.5, J2Јb,3Ј = 3.7 Hz, 1 H, 2Јb-H), 3.60
(ddd, Jgem = 13.1, J6Јa,5Ј = 4.0, J6Јa,2Јa = 0.8 Hz, 1 H, 6Јa-H), 3.79
(3S,4R,5R)-5-(Benzylamino)-1-(tert-butoxycarbonyl)-3,4-O-iso-
propylidene-3,4-dihydroxypiperidine (31): Sodium triacetoxyboro-
hydride (3 g, 14 mmol) was added to a mixture of compound 30
(2.54 g, 9.36 mmol) and benzylamine (2 mL, 18.72 mmol) in
CH2Cl2 (100 mL), and the mixture was stirred at r.t. under an ar-
gon atmosphere for 5 h. The solvents were removed in vacuo and
the title compound was obtained by chromatography on silica gel
using a linear gradient of ethanol in chloroform; yield 64% (2.16 g,
5.96 mmol); yellowish oil. 1H NMR (500.0 MHz, [D6]DMSO,
100 °C): δ = 1.30, 1.38 [2 ϫ quint, 4J = 5J = 0.6 Hz, 2 ϫ 3 H,
(CH3)2C], 1.40 {s, 9 H, [(CH3)3C]}, 2.85 (dddd, J5,6 = 11.7, 5.1,
J5,4 = 3.0, J5,3 = 0.6 Hz, 1 H, 5-H), 2.97 (t, Jgem = J6b,5 = 11.7 Hz,
1 H, 6b-H), 3.16 (dd, Jgem = 14.1, J2b,3 = 3.4 Hz, 1 H, 2b-H), 3.46
(dd, Jgem = 11.7, J6a,5 = 5.1 Hz, 1 H, 6a-H), 3.53 (dd, Jgem = 14.1,
(dd, Jgem = 14.5, J2Јa,3Ј = 3.7 Hz, 1 H, 2Јa-H), 3.88 (dddd, J5Ј,NH
7.8, J5Ј,6Ј = 7.3, 4.0, J5Ј,4Ј = 5.5 Hz, 1 H, 5Ј-H), 3.99 (q, Jvic
=
=
7.0 Hz, 2 H, CH3CH2O), 4.13 (dd, J4Ј,3Ј = 6.1, J4Ј,5Ј = 5.5 Hz, 1 H,
4Ј-H), 4.27 (dt, J3Ј,4Ј = 6.1, J3Ј,2Ј = 3.7 Hz, 1 H, 3Ј-H), 5.57 (d, Jvic
= 12.3 Hz, 1 H, 5-H), 7.54 (d, Jvic = 12.3 Hz, 1 H, 6-H), 8.57 (d,
JNH,5Ј = 7.8 Hz, 1 H, NH-1), 9.74 (br. s, 1 H, NH-3) ppm. 13C
NMR (125.7 MHz, [D6]DMSO, 100 °C): δ = 13.91 (CH3CH2O),
25.12, 27.06 [(CH3)2C], 27.75 [(CH3)3C], 42.46 (CH2-6Ј), 42.74
(CH2-2Ј), 47.93 (CH-3Ј), 67.11 (CH3CH2O), 71.12 (CH-5Ј), 74.23
(CH-4Ј), 78.81 [C(CH3)3], 98.43 (CH-5), 107.99 [C(CH3)2], 153.09
(C-2), 154.26 (CO), 161.64 (CH-6), 167.60 (C-4) ppm. IR (CHCl3):
ν
= 3429 (w), 3238 (w, br.), 3135 (w, sh), 3105 (w), 2985 (m),
˜
max
1704 (s, sh), 1687 (vs, sh), 1679 (vs), 1626 (s, sh), 1614 (s), 1548 (s),
1494 (m), 1475 (m), 1458 (m), 1408 (m), 1396 (m), 1384 (m), 1376
(m, sh), 1369 (m), 1245 (s), 1166 (s), 1109 (m), 1075 (m, sh), 1064
(m), 1016 (w), 962 (vw), 859 (w, sh), 512 (w) cm–1. HRMS-ESI:
calcd. for C19H31N3O7Na [M + Na]+ 436.20542; found 436.20527.
J2a,3 = 4.0 Hz, 1 H, 2a-H), 3.84 (s, 2 H, CH2Ph), 4.27 (ddd, J3,4
=
7.2, J3,2 = 4.0, 3.4 Hz, 1 H, 3-H), 4.44 (ddd, J4,3 = 7.2, J4,5 = 3.0,
J4,6a = 1.0 Hz, 1 H, 4-H), 7.22 (m, 1 H, p-Ph-H), 7.30 (m, 2 H, m-
Ph-H), 7.35 (m, 2 H, o-Ph-H) ppm. 13C NMR (125.7 MHz, [D6]-
DMSO, 100 °C): δ = 24.48, 26.28 [(CH3)2C], 27.88 [(CH3)3C], 41.99
(CH2-2), 42.35 (CH2-6), 49.75 (CH2Ph); 51.98 (CH-5), 71.91 (CH-
(3S,4R,5S)-1-(4,5-Dihydroxypiperidin-5-yl)uracil (29): A mixture of
28 (0.45 g, 1.05 mmol), dioxane (15 mL), and 1 m aq. H2SO4 was
stirred at 90 °C overnight. The mixture was diluted with water 3), 72.03 (CH-4), 78.25 [C(CH3)3], 107.56 [C(CH3)2], 126.20 (CH-p-
(40 mL) and applied onto a column of Dowex 50 (H+) ion ex-
Ph), 127.41 (CH-o-Ph), 127.75 (CH-mPh), 140.73 (C-i-Ph), 154.24
2180
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2172–2187

Dihydroxypiperidinyl Derivates of Nucleobases
(CO) ppm. IR (CHCl ): νmax = 3345 (vw, br.), 3088 (vw), 3066 (vw), title compound was obtained by preparative reverse-phase HPLC
˜
3
2983 (m), 2935 (m), 1686 (vs), 1604 (vw), 1586 (vw), 1495 (w), 1476
(m, sh), 1465 (m, sh), 1455 (m), 1413 (s), 1393 (m), 1384 (m), 1375
(m, sh), 1368 (s), 1355 (w, sh), 1316 (w), 1260 (m, sh), 1245 (s),
1163 (s), 1145 (m, sh), 1070 (m), 1053 (m), 1028 (w), 1000 (m), 855
(w), 700 (m), 513 (w) cm–1. HRMS (ESI): calcd. for C20H31O4N2
[M + H]+ 363.2278; found 363.2277.
in 57% yield (0.33 g, 1.45 mmol) as a white amorphous solid. [α]20
= +111.5 (c = 0.695, H2O). H NMR (500.0 MHz, D2O, 25 °C): δ
1
= 2.68 (dd, Jgem = 12.8, J2Јb,3Ј = 11.4 Hz, 1 H, 2Јb-H), 2.90 (dd,
Jgem = 12.1, J6Јb,5Ј = 4.3 Hz, 1 H, 6Јb-H), 2.92 (dd, Jgem = 12.8,
J2Јa,3Ј = 5.1 Hz, 1 H, 2Јa-H), 3.07 (t, Jgem = J6Јa,5Ј = 12.1 Hz, 1 H,
6Јa-H), 3.82 (ddd, J3Ј,2Ј = 11.4, 5.1, J3Ј,4Ј = 2.9 Hz, 1 H, 3Ј-H), 4.15
(dd, J4Ј,3Ј = 2.9, J4Ј,5Ј = 1.7 Hz, 1 H, 4Ј-H), 4.56 (td, J5Ј,6Ј = 12.1,
4.3, J5Ј,4Ј = 1.7 Hz, 1 H, 5Ј-H), 5.80 (d, J5,6 = 8.1 Hz, 1 H, 5-H),
7.72 (d, J6,5 = 8.1 Hz, 1 H, 6-H) ppm. 13C NMR (125.7 MHz, D2O,
25 °C): δ = 43.20 (CH2-6Ј), 46.47 (CH2-2Ј), 57.19 (CH-5Ј), 70.67
(CH-3Ј), 71.85 (CH-4Ј), 103.62 (CH-5), 147.43 (CH-6), 155.01 (C-
(3S,4R,5R)-5-Amino-1-(tert-butoxycarbonyl)-3,4-O-isopropylidene-
3,4-dihydroxypiperidine (32): Compound 31 (2.16 g, 5.96 mmol) in
methanol (200 mL) was hydrogenated in the presence of Pd/C cata-
lyst (0.6 g) overnight. The catalyst was removed by filtration
through Celite and the solvent was removed in vacuo. The title
compound was obtained in 95% yield (1.38 g, 5.066 mmol) as a
colorless oil. 1H NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.30,
1.36 [2ϫs, 2 ϫ3 H, (CH3)2C], 1.41 {s, 9 H, [(CH3)3C]}, 2.92 (m,
6b,5-H), 3.14 (dd, Jgem = 14.2, J2b,3 = 3.1 Hz, 1 H, 2b-H), 3.28 (m,
1 H, 6a-H), 3.57 (dd, Jgem = 14.2, J2a,3 = 3.6 Hz, 1 H, 2a-H), 4.24
(m, 1 H, 4-H), 4.29 (ddd, J3,4 = 7.3, J3,2 = 3.6, 3.1 Hz, 1 H, 3-
H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ = 24.43,
26.21 [(CH3)2C], 27.92 [(CH3)3C], 41.69 (CH2-2), 44.85 (CH2-6),
46.63 (CH-5), 72.05 (CH-3), 74.71 (CH-4), 78.18 [C(CH3)3], 107.41
2), 169.14 (C-4) ppm. IR (KBr): ν
= 3400 (m, v br., sh), 3298
˜
max
(m, br.), 3190 (br. m, sh), 1687 (vs, br.), 1618 (m, sh), 1463 (m),
1384 (m), 1263 (m), 1078 (m), 1060 (w, sh), 1016 (w), 994 (w), 810
(w), 765 (w), 719 (w) cm–1. HRMS-ESI: calcd. for C9H14O4N3 [M
+ H]+ 228.0979; found 228.0978.
(3S,4R,5R)-5-O-Benzyl-1-(tert-butoxycarbonyl)-3,4-O-isopropyl-
idene-3,4,5-trihydroxypiperidine (35): Sodium hydride (6.9 g,
172.2 mmol) was added to a solution of 24 (15.69 g, 57.4 mmol)
and benzyl bromide (10 mL, 86.1 mmol) in THF (600 mL) at room
temp. The reaction mixture was heated to reflux for 5 h, then co-
oled to 0 °C, and acetic acid (10 mL, 172.2 mmol) was slowly added
(CAUTION! hydrogen evolution!). The solvents were then removed
in vacuo and the desired product was obtained by flash chromatog-
raphy on silica gel using a linear gradient of ethyl acetate in tolu-
ene; yield 75 % (15.7 g, 43.23 mmol). 1H NMR (500.0 MHz,
[D6]DMSO, 80 °C): δ = 1.29, 1.36 [2ϫs, 2 ϫ3 H, (CH3)2C], 1.40
{s, 9 H, [(CH3)3C]}, 3.16 (br. dd, Jgem = 14.3, J2b,3 = 3.4 Hz, 1 H,
2b-H), 3.21 (dd, Jgem = 11.6, J6b,5 = 10.6 Hz, 1 H, 6b-H), 3.41 (ddd,
Jgem = 11.6, J6a,5 = 5.4, J6a,4 = 1.0 Hz, 1 H, 6a-H), 3.54 (dd, Jgem
= 14.3, J2a,3 = 3.8 Hz, 1 H, 2a-H), 3.78 (ddd, J5,6 = 10.6, 5.4, J5,4
= 2.9 Hz, 1 H, 5-H), 4.29 (ddd, J3,4 = 7.3, J3,2 = 3.8, 3.4 Hz, 1 H,
3-H), 4.53 (ddd, J4,3 = 7.3, J4,5 = 2.9, J4,6a = 1.0 Hz, 1 H, 4-H),
4.58, 4.64 (2ϫd, Jgem = 12.0 Hz, 2ϫ1 H, CH2Ph), 7.29 (m, 1 H,
p-Ph-H), 7.35 (m, 4 H, o,m-Ph-H) ppm. 13C NMR (125.7 MHz,
[D6]DMSO, 80 °C): δ = 24.63, 26.30 [(CH3)2C], 27.97 [(CH3)3C],
41.28 (CH2-6), 42.21 (CH2-2), 70.26 (CH2Ph), 71.43 (CH-4), 72.09
(CH-5), 72.21 (CH-3), 78.58 [C(CH3)3], 108.18 [C(CH3)2], 127.26
(CH-p-Ph), 127.32 (CH-o-Ph), 128.02 (CH-mPh), 138.33 (C-i-Ph),
[C(CH ) ], 154.29 (CO) ppm. IR (CHCl ): ν = 3385 (w), 3321
˜
max
3 2
3
(vw, br.), 2983 (m), 1687 (vs), 1583 (w, br.), 1475 (m), 1465 (m, sh),
1415 (s), 1394 (m), 1383 (m), 1376 (m, sh), 1368 (s), 1246 (s), 1172
(s, sh), 1162 (s), 1140 (m), 1051 (m), 1005 (w, sh), 854 (m), 513
(w) cm–1. HRMS-ESI: calcd. for C13H25O4N2 [M + H]+ 273.18088;
found 273.18087.
(3S,4R,5R)-5-[3-(3-Ethoxyacryloyl)ureido]-1-(tert-butoxycarbonyl)-
3,4-O-isopropylidene-3,4-dihydroxypiperidine (33): 2-Nitrophenyl
(3-ethoxyacryloyl)carbamate (0.84 g, 3 mmol) was added to a solu-
tion of the amine 32 (0.7 g, 2.57 mmol) in dioxane (25 mL), and
the reaction mixture was stirred at r.t. for 4 h. The solvent was
removed in vacuo and the title compound was obtained by
chromatography on silica gel using a linear gradient of ethyl acetate
in toluene in 69% yield (0.73 g, 1.77 mmol) as a yellowish foam. 1H
NMR (500.0 MHz, [D6]DMSO, 80 °C): δ = 1.27 (t, Jvic = 7.1 Hz, 3
H, CH3CH2O), 1.31, 1.39 [2ϫs, 2 ϫ3 H, (CH3)2C], 1.41 {s, 9 H,
[(CH3)3C]}, 3.00 (t, Jgem = J6Јb,5Ј = 11.6 Hz, 6Јb-H), 3.25 (br. d,
Jgem = 14.4 Hz, 1 H, 2Јb-H), 3.64 (dd, Jgem = 11.6, J6Јa,5Ј = 5.2 Hz,
1 H, 6Јa-H), 3.64 (dd, Jgem = 14.4, J2Јa,3Ј = 2.6 Hz, 1 H, 2Јa-H),
3.98 (q, Jvic = 7.1 Hz, 2 H, CH3CH2O), 4.09 (m, 1 H, 3Ј-H), 4.37
(m, 1 H, 4Ј-H), 4.39 (m, 1 H, 5Ј-H), 5.54 (d, Jvic = 12.3 Hz, 1 H,
5-H), 7.57 (d, Jvic = 12.3 Hz, 1 H, 6-H), 8.87 (d, JNH,3Ј = 8.4 Hz,
1 H, NH-1), 9.94 (br. s, 1 H, NH-3) ppm. 13C NMR (125.7 MHz,
[D6]DMSO, 80 °C): δ = 14.17 (CH3CH2O), 24.45, 26.24 [(CH3)2C],
27.99 [(CH3)3C], 41.26 (CH2-6Ј), 41.45 (CH2-2Ј), 45.09 (CH-5Ј),
67.31 (CH3CH2O), 71.94 (CH-3Ј), 72.12 (CH-4Ј), 78.74 [C(CH3)3],
98.38 (CH-5), 108.14 [C(CH3)2], 153.14 (C-2), 154.33 (CO), 162.10
154.30 (CO) ppm. IR (CHCl ): νmax = 3082 (w), 3067 (w), 2983 (s),
˜
3
1688 (vs, br.), 1606 (vw), 1586 (vw), 1496 (m), 1474 (s), 1464 (s,
sh), 1455 (s), 1415 (vs, br.), 1394 (s), 1384 (vs), 1374 (s, sh), 1368
(vs), 1314 (m), 1260 (s, sh), 1245 (vs), 1239 (vs), 1172 (vs, sh), 1164
(vs, br.), 1148 (s, sh), 1092 (vs), 1070 (s), 1052 (s, sh), 1028 (m, sh),
1010 (s, sh), 912 (w), 855 (s), 699 (s), 513 (m), 461 (vw) cm–1
.
HRMS-ESI: calcd. for C20H29O5NNa [M + Na]+ 386.1938; found
386.1937.
(3R,4S,5S)-3-O-Benzyl-1-(tert-butoxycarbonyl)-3,4,5-trihydroxy-
piperidine (36): Compound 35 (33 g, 91 mmol) was dissolved in
1.5% TFA/CH2Cl2 (600 mL) containing water (4 mL). The reaction
mixture was vigorously stirred and monitored by TLC (EtOH/
CHCl3, 10%). Upon completion, NaHCO3 (20 g) was added and
the suspension was vigorously stirred until a neutral pH value was
reached. The reaction mixture was filtered, and the filtrate was con-
centrated in vacuo. Preparative chromatography on silica gel using
a linear gradient of ethanol in chloroform provided the desired
product in 81% yield (23.82 g, 73.71 mmol). 1H NMR (500.0 MHz,
[D6]DMSO, 80 °C): δ = 1.39 (s, 9 H, [(CH3)3C]), 2.96 (br. dd, Jgem
(CH-6), 167.67 (C-4) ppm. IR (CHCl ): νmax = 3428 (w), 3270 (br.
˜
3
m, sh), 3238 (m, br.), 3133 (w, br., sh), 3106 (w, br.), 2984 (s), 1704
(vs, sh), 1686 (vs), 1677 (vs, sh), 1626 (s), 1614 (s), 1542 (vs), 1495
(m), 1474 (s), 1458 (s), 1411 (s), 1394 (s), 1384 (s), 1376 (m, sh),
1368 (s), 1242 (s), 1172 (vs, sh), 1163 (vs), 1137 (s), 1075 (m), 1052
(m), 1004 (m), 977 (w), 962 (w), 850 (m), 512 (m) cm–1. HRMS-
ESI: calcd. for C19H31O7N3Na [M + Na]+ 436.2054; found
436.2052.
(3S,4R,5R)-1-(4,5-Dihydroxypiperidin-5-yl)uracil (34): A mixture of
compound 33 (0.73 g, 1.77 mmol) and Dowex 50 H+ (10 g) in diox-
ane (40 mL) was stirred at 90 °C for 3 h. The reaction mixture was
then poured into an empty column. The resin was washed consecu-
tively with 50% aq. ethanol (100 mL) and water (100 mL), and the
= 12.6, J6b,5 = 9.9 Hz, 1 H, 6b-H), 3.07 (dd, Jgem = 12.6, J2b,3
=
9.8 Hz, 1 H, 2b-H), 3.35 (ddd, J3,2 = 9.8, 4.5, J3,4 = 2.5 Hz, 1 H,
3-H), 3.39 (dddd, J5,6 = 9.9, 4.7, J5,OH = 6.9, J5,4 = 2.5 Hz, 1 H, 5-
4
title compound was eluted with 3% aq. ammonia (250 mL). The H), 3.57 (dddd, Jgem = 12.6, J6a,5 = 4.7, J = 1.4, 0.7 Hz, 1 H, 6a-
Eur. J. Org. Chem. 2011, 2172–2187
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2181

D. Rejman et al.
FULL PAPER
H), 3.66 (br. dd, Jgem = 12.6, J2a,3 = 4.5 Hz, 1 H, 2a-H), 3.99 (br.
chromatography on silica gel using a linear gradient of ethyl acetate
in toluene. The mixture was dissolved in ethanol (300 mL) and sub-
jected to hydrogenation in the presence of Pd/C catalyst (2 g) over-
night. The title trifluoroacetamide isomers were finally separated
by chromatography on silica gel using a linear gradient of ethyl
acetate in toluene to provide 38b (24%, 5.79 mmol) and 38a (43%,
dt, J4,OH = 3.6, J4,3 = J4,5 = 2.5 Hz, 1 H, 4-H), 4.33 (br. d, JOH,4
=
3.6 Hz, 1 H, OH-4), 4.36 (br. d, JOH,5 = 6.9 Hz, 1 H, OH-5), 3.54,
3.61 (2ϫd, Jgem = 12.1 Hz, 2ϫ1 H, CH2Ph), 7.28 (m, 1 H, p-Ph-
H), 7.34 (m, 2 H, m-Ph-H), 7.36 (m, 2 H, o-Ph-H) ppm. 13C NMR
(125.7 MHz, [D6]DMSO, 80 °C): δ = 27.87 [(CH3)3C], 41.26 (CH2-
2), 44.16 (CH2-6), 67.24 (CH-5), 68.20 (CH-4), 69.57 (CH2Ph), 10.54 mmol) as white amorphous solids (yields calculated over four
74.98 (CH-3), 78.70 [C(CH3)3], 127.11 (CH-p-Ph), 127.24 (CH-o- reaction steps).
Ph), 128.91 (CH-mPh), 138.48 (C-i-Ph), 154.11 (CO) ppm. IR
Compound 38a: 1H NMR (500.0 MHz, [D6]DMSO, 80 °C): δ = 1.40
(CHCl ): ν
= 3570 (s), 3495 (s, br.), 3090 (w), 3067 (m), 2981
˜
3
max
{s, 9 H, [(CH3)3C]}, 2.77 (m, 1 H, 6b-H), 2.95 (dd, Jgem = 12.9,
J2b,3 = 1.5 Hz, 1 H, 2b-H), 3.57 (br. d, J4,5 = 9.4 Hz, 1 H, 4-H),
3.78 (br. m, 1 H, 3-H), 3.82 (br. m, 1 H, 2a-H), 3.85 (br. m, 1 H,
6a-H), 3.90 (td, J5,4 = 9.4, J5,6 = 9.4, 4.7 Hz, 1 H, 5-H), 4.49 (br.
d, JOH,3 = 3.3 Hz, 1 H, OH-3), 4.56 (br. d, JOH,4 = 4.3 Hz, 1 H,
OH-4), 8.94 (br. s, 1 H, NH) ppm. 13C NMR (125.7 MHz,
[D6]DMSO, 80 °C): δ = 27.96 [(CH3)3C], 44.54 (CH2-6), 47.49
(CH2-2), 48.66 (CH-5), 66.85 (CH-3), 70.66 (CH-4), 78.70
[C(CH3)3], 115.83 (q, JC,F = 288.6 Hz, CF3), 154.51 (CO), 156.40
(q, JC,F = 36.1 Hz, COCF3) ppm. 19F NMR (470.3 MHz, [D6]-
(s), 1686 (vs, v br.), 1610 (w, sh), 1587 (w), 1496 (m), 1475 (s), 1464
(s, sh), 1455 (vs), 1428 (vs, br.), 1394 (vs), 1368 (vs), 1312 (s, sh),
1236 (vs, br.), 1167 (vs, br.), 1135 (vs), 1093 (vs), 1076 (vs), 1054
(vs), 1029 (s), 1003 (m), 913 (w), 699 (s) cm–1. HRMS-ESI: calcd.
for C17H25O5NNa [M + Na]+ 346.1625; found 346.1625.
(3R,4R,5S)-3-O-Benzyl-1-(tert-butoxycarbonyl)-3,4,5-trihydroxy-
piperidin-3,4-yl Sulfite (37): Thionyl chloride (5.32 mL,
73.15 mmol) was added dropwise to a solution of 36 (19.7 g,
60.96 mmol), and triethylamine (21.24 mL, 152.4 mmol) in CH2Cl2
(600 mL) at 0 °C. After 1 h, the temperature was increased to r.t.
and the reaction mixture was extracted with saturated aq. NaHCO3
(300 mL). The organic phase was dried with sodium sulfate and
concentrated in vacuo. The title product was obtained as a mixture
of two diastereoisomers (due to chiral S atom), after purification
by chromatography on silica gel using a linear gradient of ethanol
in chloroform; yield 98 % (22.07 g, 59.74 mmol). 1H NMR
(500.0 MHz, [D6]DMSO, 100 °C): δ = 1.39, 1.40 {2ϫs, 2 ϫ9 H,
[(CH3)3C]}, 3.16 (dd, Jgem = 12.1, J2b,3 = 10.6 Hz, 1 H, 2b-H), 3.22
(dd, Jgem = 13.3, J2b,3 = 3.1 Hz, 1 H, 2b-H), 3.49 (dd, Jgem = 15.1,
J6b,5 = 3.7 Hz, 1 H, 6b-H), 3.63 (dd, Jgem = 14.4, J6b,5 = 6.0 Hz, 1
H, 6b-H), 3.68–3.75 (m, 3 H, 2ϫH-2a, 6a-H), 3.89 (dt, J3,4 = 6.7,
J3,2 = 3.1 Hz, 1 H, 3-H), 3.96 (ddd, J3,2 = 10.6, 5.3, J3,4 = 3.3 Hz,
1 H, 3-H), 3.98 (br. dd, Jgem = 15.1, J6a,5 = 3.5 Hz, 1 H, 6a-H),
4.57, 4.63, 4.67, 4.70 (4ϫd, Jgem = 12.1 Hz, CH2Ph), 4.94–5.00 (m,
2 H, 5-H), 5.11, 5.26 (2ϫm, 2ϫ1 H, 4-H), 7.26–7.38 (m, 10 H,
o,m,p-Ph-H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ
= 27.72, 27.75 [(CH3)3C], 41.50, 41.59, 41.79, 42.76 (6, CH2-2),
70.37 (CH2Ph); 70.39 (CH-3), 70.76 (CH2Ph), 71.04 (CH-3), 75.60,
77.62 (CH-5), 77.96 (CH-4), 79.10, 79.12 [C(CH3)3], 80.22 (CH-4),
126.96, 127.07 (CH-p-Ph), 127.22, 127.25 (CH-o-Ph), 127.80,
127.91 (CH-mPh), 137.76, 137.83 (C-i-Ph), 153.52, 153.95
DMSO, 80 °C): δ = –70.76 ppm. IR (KBr): ν
= 3433 (m, br.),
˜
max
3325 (br. m, sh), 2982 (m), 1708 (vs), 1674 (s), 1558 (m), 1479 (m),
1464 (m, sh), 1434 (s), 1396 (m), 1369 (s), 1305 (m), 1247 (s), 1212
(s), 1187 (vs, sh), 1165 (vs), 1140 (s), 1081 (m), 727 (m), 519
(w) cm–1. HRMS-ESI: calcd. for C12H18O5N2F3 (M – H)–
327.1173; found 327.1175.
Compound 38b: 1H NMR (500.0 MHz, [D6]DMSO, 80 °C): δ = 1.42
{s, 9 H, [(CH3)3C]}, 2.96 (br. dd, Jgem = 13.5, J2b,3&6b,5 = 10.5 Hz,
2 H, 2b,6b-H), 3.42 (ddt, J3,2&5,6 = 10.5, 5.2, J3,4&5,4 = 9.6,
J3,OH&5,OH = 5.2 Hz, 2 H, 3,5-H), 3.49 (br. t, J4,3 = J4,5 = 9.6 Hz,
1 H, 4-H), 4.39 (ddd, Jgem = 13.5, J2a,3&6a,5 = 5.2, J2a,4&6a,4
=
2.0 Hz, 2 H, 2a,6a-H), 4.95 (br. d, JOH,3&OH,5 = 5.2 Hz, 2 H, OH-
3,5), 8.74 (br. s, 1 H, NH) ppm. 1 3 C NMR (125.7 MHz,
[D6]DMSO, 80 °C): δ = 27.93 [(CH3)3C], 49.02 (CH2-2,6), 61.04
(CH-4), 66.60 (CH-3,5), 79.02 [C(CH3)3], 116.08 (q, JC,F
=
288.9 Hz, CF3), 153.76 (CO), 156.54 (q, JC,F = 35.5 Hz,
COCF3) ppm. 19F NMR (470.3 MHz, [D6]DMSO, 80 °C): δ =
–70.81 ppm. IR (KBr): νmax = 3419 (m, br.), 3340 (m, sh), 3275 (m,
˜
sh), 2982 (w), 1726 (s, sh), 1707 (vs), 1672 (vs), 1567 (m, br.), 1480
(m), 1466 (m), 1436 (s), 1396 (m), 1370 (m), 1309 (m), 1254 (m,
sh), 1215 (s), 1184 (vs), 1165 (vs), 1149 (vs, sh), 1095 (m), 1068 (m),
1023 (m), 728 (w), 518 (vw) cm–1. HRMS-ESI: calcd. for
C12H18O5N2F3 (M – H)– 327.1173; found 327.1169.
(CO) ppm. IR (KBr): ν
= 3092 (w), 3071 (w), 3026 (w), 3007
˜
max
(w), 2977 (m), 1693 (vs), 1609 (w), 1586 (w), 1499 (w), 1478 (m),
1464 (m, sh), 1454 (s), 1428 (s), 1391 (w), 1365 (m), 1316 (w), 1306
(w), 1281 (m), 1275 (m), 1240 (s), 1205 (s), 1171 (s), 1095 (m), 1075
(m), 1031 (w), 1012 (s), 998 (m, sh), 763 (s), 732 (s), 695 (m), 674
(m), 460 (w) cm–1. HRMS-ESI: calcd. for C17H23O6NSNa [M +
Na]+ 392.1138; found 392.1137.
(3R,4S,5R)-5-Amino-1-(tert-butoxycarbonyl)-3,4-dihydroxypiperid-
ine (39a): Dowex 1 (OH– form; 8 g) was added to a solution of 38a
(6.73 mmol) in a mixture of ethanol (25 mL) and water (10 mL).
The reaction mixture was stirred at r.t. for 30 min, then the resin
was filtered off and the filtrate was concentrated in vacuo to pro-
vide the desired product 39a in 88% yield (1.38 g, 5.94 mmol) as a
white amorphous solid. 1H NMR (500.0 MHz, [D6]DMSO, 80 °C):
δ = 1.42 {s, 9 H, [(CH3)3C]}, 2.68 (dd, Jgem = 12.8, J6b,5 = 8.1 Hz,
1 H, 6b-H), 2.84 (ddd, J5,6 = 8.1, 4.3, J5,4 = 7.7 Hz, 1 H, 5-H), 3.08
(dd, Jgem = 13.3, J2b,3 = 2.9 Hz, 1 H, 2b-H), 3.19 (dd, J4,5 = 7.7,
J4,3 = 3.2 Hz, 1 H, 4-H), 3.63 (ddd, Jgem = 13.3, J2a,3 = 2.9, J2a,6a
(3R,4S,5R)-1-(tert-Butoxycarbonyl)-3,4-dihydroxy-5-(trifluoroacet-
amido)piperidine (38a), (3S,4R,5R)-1-(tert-Butoxycarbonyl)-3,5-di-
hydroxy-4-(trifluoroacetamido)piperidine (38b): A mixture of com-
pound 37 (9 g, 24.36 mmol) and LiN3 (5 g, 100 mmol) in DMF
(140 mL) was stirred at 90 °C for 3 d. The solvent was removed in
vacuo and the crude material was purified by chromatography on
silica gel using a linear gradient of ethyl acetate in toluene to pro-
vide a mixture of isomeric azido derivatives (ratio, 1:2) in 92% yield
(7.78 g, 22.33 mmol) as a yellowish thick oil. This mixture of iso-
mers was then dissolved in ethanol (400 mL) and subjected to hy-
drogenation in the presence of Pd/C catalyst (1 g) overnight. The
catalyst was removed by filtration through Celite, then ethyl trifluo-
= 1.7 Hz, 1 H, 2a-H), 3.69 (ddd, Jgem = 12.8, J6a,5 = 4.3, J6a,2a
=
1.7 Hz, 1 H, 6a-H), 3.72 (ddd, J3,2 = 5.4, 2.9, J3,4 = 3.2 Hz, 1 H,
3-H), 3.95, 4.02 (2 br. d, 2 ϫ 1 H, 2 ϫ OH) ppm. 13C NMR
(125.7 MHz, [D6]DMSO, 80 °C): δ = 27.88 [(CH3)3C], 47.04 (CH2-
2), 47.54 (CH2-6), 49.13 (CH-5), 66.27 (CH-3), 74.66 (CH-4), 78.05
[C(CH ) ], 154.50 (CO) ppm. IR (KBr): νmax = 3499 (m), 3456 (s),
˜
3 3
roacetate (3.6 mL, 30 mmol) was added and the mixture was stirred 3359 (s), 3345 (s), 3333 (s), 3288 (m), 2977 (s), 1683 (vs), 1665 (vs),
at r.t. overnight. The solvent was removed in vacuo and the ex- 1609 (m), 1593 (m), 1481 (s), 1457 (s), 1439 (vs), 1428 (s, sh), 1390
pected mixture of isomeric trifluoroacetamides was obtained by (s), 1366 (s), 1247 (s), 1202 (s), 1174 (vs), 1145 (vs), 1089 (s, sh),
2182
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2172–2187

Dihydroxypiperidinyl Derivates of Nucleobases
1076 (s, sh), 1056 (m, sh) cm– 1 . HRMS-ESI: calcd. for
C10H20O4N2Na [M + Na]+ 255.1315; found 255.1316.
(3R,4S,5R)-5-[(5-Amino-6-chloropyrimidin-4-yl)amino]-1-(tert-
butoxycarbonyl)-3,4-dihydroxypiperidine (43): A mixture of amine
39a (2 g, 8.61 mmol), 3-amino-4,6-dichloropyrimidine (2.8 g,
17.22 mmol), and triethylamine (5.1 mL, 37 mmol) in n-butanol
(80 mL) was stirred in a pressure vessel at 130 °C for 3 d. The sol-
vent was removed in vacuo and the title compound was purified
by chromatography on silica gel using a linear gradient of ethanol
in chloroform; yield 57 % (1.76 g, 4.89 mmol); brown foam. 1H
NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.35 [s, 9 H,
(3S,4R,5R)-4-Amino-1-(tert-butoxycarbonyl)-3,5-dihydroxypiperid-
ine (39b): Dowex 1 anion exchanger (OH– form; 8 g) was added to a
solution of 38b (1.47 g, 4.48 mmol) in a solvent mixture of ethanol
(20 mL) and water (10 mL). The reaction mixture was stirred at r.t.
for 2 h, then the resin was filtered off and the filtrate was concen-
trated in vacuo to provide the desired product in 91% yield (0.95 g,
4.09 mmol) as a white foam. 1H NMR (500.0 MHz, [D6]DMSO,
(CH3)3C], 3.07 (m, 1 H, 6Јb-H), 3.23 (br. dd, Jgem = 13.3, J2Јb,3Ј
=
100 °C): δ = 1.41 {s, 9 H, [(CH3)3C]}, 2.35 (br. t, J4,3 = J4,5
=
3.1 Hz, 1 H, 2Јb-H), 3.57 (br. dd, Jgem = 13.3, J2Јa,3Ј = 5.8 Hz, 1
H, 2Јa-H), 3.67 (dd, J4Ј,5Ј = 7.7, J4Ј,3Ј = 3.0 Hz, 1 H, 4Ј-H), 3.81
(m, 1 H, 6Јa-H), 3.88 (dt, J3Ј,2Јa = 6.0, J3Ј,2Јb = J3Ј,4Ј = 3.0 Hz, 1 H,
3Ј-H), 4.22 (m, 1 H, 5Ј-H), 4.88 (br. s, 2 H, NH2), 6.25 (br. d, JNH,5Ј
= 6.9 Hz, 1 H, NH), 7.76 (s, 1 H, 2-H) ppm. 1 3 C NMR
(125.7 MHz, [D6]DMSO, 100 °C): δ = 27.79 [(CH3)3C], 44.18
(CH2-6Ј), 46.08 (CH2-2Ј), 50.32 (CH-5Ј), 66.14 (CH-3Ј), 70.94
(CH-4Ј), 78.25 [C(CH3)3], 123.47 (C-5), 137.66 (C-6), 145.38 (CH-
8.9 Hz, 1 H, 4-H), 2.47 (br. dd, Jgem = 13.1, J2b,3&6b,5 = 10.4 Hz, 2
H, 2b,6b-H), 3.04 (ddd, J3,2&5,6 = 10.4, 5.3, J3,4&5,4 = 8.9 Hz, 2 H,
3,5-H), 3.92, 3.93 (2ϫdd, Jgem = 13.1, J2a,3&6a,5 = 5.3 Hz, 2ϫ1 H,
2a,6a-H), 4.65 (br. s, 2 H, OH-3,5) ppm. 13C NMR (125.7 MHz,
[D6]DMSO, 100 °C): δ = 27.81 [(CH3)3C], 48.43 (CH2-2,6), 61.85
(CH-4), 69.75 (CH-3,5), 78.58 [C(CH3)3], 153.76 (CO) ppm. IR
(KBr): ν
= 3562 (m), 3491 (m), 3413 (br. m, sh), 3373 (s), 3341
˜
max
(s, br.), 3313 (s, sh), 3085 (w, v br.), 3000–2400 (m, v br.), 2996 (m),
2974 (m), 1691 (vs), 1667 (s), 1632 (w), 1563 (w), 1485 (s), 1465
(m), 1425 (vs), 1393 (m), 1367 (s), 1258 (s), 1236 (s), 1173 (vs), 1152
(m, sh), 1138 (m), 1074 (s), 1050 (vs), 1014 (m, br.) cm–1. HRMS-
ESI: calcd. for C10H20O4N2Na [M + Na]+ 255.1315; found
255.1313.
2), 152.07 (C-4), 155.35 (CO) ppm. IR (CHCl ): ν
= 3417 (s,
˜
3
max
br.), 3255 (br. m, sh), 2976 (m), 2685 (w, v br., sh), 1693 (s, br.),
1660 (s, br.), 1633 (m, sh), 1578 (vs), 1495 (m, sh), 1476 (m, sh),
1462 (m), 1423 (s), 1394 (m), 1367 (m), 1338 (w), 1244 (m), 1212
(m), 1166 (s), 1137 (m), 1053 (m), 848 (w), 769 (w) cm–1. HRMS-
ESI: calcd. for C14H23O4N5Cl [M + H]+ 360.1433; found 360.1436.
(3R,4S,5R)-6-Chloro-9-[1(-tert-butoxycarbonyl)-3,4-dihydroxypiper-
idin-5-yl]purine (44): Compound 43 (1.08 g, 3 mmol) was dissolved
in diethoxymethyl acetate (30 mL, 180 mmol) and the solution was
stirred under an argon atmosphere at r.t. for 3 h. The reaction mix-
ture was stirred at 80 °C for 2 d, then the excess diethoxymethyl
acetate was removed in vacuo and the title compound was obtained
by flash chromatography on silica gel using a linear gradient of
ethyl acetate in toluene; yield 49% (0.54 g, 1.46 mmol); brownish
foam. 1H NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.42 [s, 9
H, (CH3)3C], 3.53 (dd, Jgem = 13.2, J6Јb,5Ј = 11.1 Hz, 1 H, 6Јb-H),
3.53 (dd, Jgem = 14.9, J2Јb,3Ј = 3.4 Hz, 1 H, 2Јb-H), 4.08 (ddd, Jgem
= 13.2, J6Јa,5Ј = 4.8, J6Јa,2Јa = 1.6 Hz, 1 H, 6Јa-H), 4.22 (ddd, Jgem
(3R,4S,5R)-1-(tert-Butoxycarbonyl)-3,4-dihydroxy-5-[3-(3-ethoxy-
acryloyl)ureido]piperidine (40): 4-Nitrophenyl (3-ethoxyacryloyl)-
carbamate (1 g, 3.5 mmol) was added to a solution of amine 39a
(0.44 g, 1.89 mmol) in dioxane (40 mL). The reaction mixture was
stirred at r.t. for 4 h, then the solvent was removed in vacuo and
the title compound was purified by chromatography on silica gel
using a linear gradient of ethanol in chloroform, as a yellowish
foam in 79% yield (0.56 g, 1.5 mmol). 1H NMR (500.0 MHz, [D6]-
DMSO, 100 °C): δ = 1.27 (t, Jvic = 7.0 Hz, 3 H, CH3CH2O), 1.40
{s, 9 H, [(CH3)3C]}, 3.19 (dd, Jgem = 13.2, J6Јb,5Ј = 6.3 Hz, 1 H,
6Јb-H), 3.34 (dd, Jgem = 13.0, J2Јb,3Ј = 6.6 Hz, 1 H, 2Јb-H), 3.38
(dd, Jgem = 13.0, J2Јa,3Ј = 4.1 Hz, 1 H, 2Јa-H), 3.57–3.65 (m, 3 H,
6Јa,3Ј,4Ј-H), 3.81 (dtd, J5Ј,NH = 7.8, J5Ј,4Ј = 6.3, J5Ј,6Ј = 6.3, 3.7 Hz,
1 H, 5Ј-H), 3.98 (q, Jvic = 7.0 Hz, 2 H, CH3CH2O), 4.38 (br. s, 1
H, OH-3Ј), 4.49 (br. s, 1 H, OH-4Ј), 5.56 (d, Jvic = 12.3 Hz, 1 H,
5-H), 7.52 (d, Jvic = 12.3 Hz, 1 H, 6-H), 8.51 (d, JNH,5Ј = 7.8 Hz,
1 H, NH-1), 9.68 (br. s, 1 H, NH-3) ppm. 13C NMR (125.7 MHz,
[D6]DMSO, 100 °C): δ = 13.95 (CH3CH2O), 27.79 [(CH3)3C], 43.74
(CH2-6Ј), 45.61 (CH2-2Ј), 48.97 (CH-5Ј), 65.88 (CH-3Ј), 67.07
(CH3CH2O), 70.19 (CH-4Ј), 78.48 [C(CH3)3], 98.52 (CH-5), 153.25
(C-2), 154.17 (CO), 161.46 (CH-6), 167.49 (C-4) ppm. IR (KBr):
= 14.9, J2Јa,3Ј = 3.4, J2Јa,6Јa = 1.6 Hz, 1 H, 2Јa-H), 4.44 (dt, J3Ј,4Ј
=
5.6, J3Ј,2Ј = 3.4 Hz, 1 H, 3Ј-H), 4.89 (dd, J4Ј,5Ј = 8.3, J4Ј,3Ј = 5.6 Hz,
1 H, 4Ј-H), 5.04 (ddd, J5Ј,6Ј = 11.1, 4.8, J5Ј,4Ј = 8.3 Hz, 1 H, 5Ј-H),
8.71 (s, 1 H, 8-H), 8.76 (s, 1 H, 2-H) ppm. 13C NMR (125.7 MHz,
[D6]DMSO, 100 °C): δ = 27.69 [(CH3)3C], 43.44 (CH2-2Ј), 43.95
(CH2-6Ј), 54.71 (CH-5Ј), 73.22 (CH-3Ј), 73.56 (CH-4Ј), 79.51
[C(CH3)3], 131.00 (C-5), 145.61 (CH-8), 149.34 (C-6), 151.10 (CH-
2), 151.81 (C-4), 153.83 (CO) ppm. IR (KBr): ν
= 3422 (w, v
˜
max
br.), 2979 (m), 1700 (vs), 1592 (s), 1561 (s), 1489 (m), 1478 (m),
1436 (s, sh), 1418 (s, br.), 1400 (s, sh), 1367 (m), 1337 (s), 1230 (m),
1200 (s), 1166 (vs), 1149 (s, sh), 1090 (s), 1017 (m), 935 (s), 793 (w),
649 (w), 637 (m) cm–1. HRMS-ESI: calcd. for C15H21O4N5Cl [M
+ H]+ 370.1282; found 370.1284.
ν
= 3500 (br. m, sh), 3418 (m, v br.), 3272 (m, br.), 3143 (w,
˜
max
br.), 2982 (m), 1698 (vs, sh), 1692 (vs), 1678 (vs), 1613 (s), 1556 (s,
sh), 1545 (s), 1500 (w, sh), 1426 (m), 1396 (w), 1368 (m), 1480 (m),
1473 (m, sh), 1246 (s), 1211 (m), 1171 (s, br.), 1143 (s), 1063 (m),
985 (w), 978 (w, sh) cm–1. HRMS-ESI: calcd. for C16H27O7N3Na
[M + Na]+ 396.1741; found 396.1742.
(3R,4S,5R)-9-(3,4-Dihydroxypiperidin-5-yl)adenine (45): Concen-
trated aq. ammonia (20 mL) was added to chloropurine derivative
44 (0.31 g, 0.84 mmol) and the reaction mixture was stirred at r.t.
for 3 d. The reaction mixture was concentrated in vacuo, 3 m HCl
(30 mL) was added, and the reaction mixture was stirred at 80 °C
overnight. The reaction mixture was diluted with water (40 mL)
and applied onto a column of Dowex 50 H+ ion exchanger. The
resin was then washed consecutively with 50 % aq. ethanol
(200 mL) and water (100 mL), and the title compound was eluted
with 3% aq. ammonia. The product was finally purified by reverse-
phase preparative HPLC to provide 45 in 50 % yield (0.104 g,
0.416 mmol) as a white amorphous solid; [α]20 = +80 (c = 0.236,
(3R,4S,5R)-1-(3,4-Dihydroxypiperidin-5-yl)uracil (41): A mixture of
40 (0.84 g, 2.25 mmol) and Dowex 50 (H+) ion exchange resin (9 g)
in dioxane (30 mL) was stirred at 90 °C for 3 h. The reaction mix-
ture was then poured into an empty column. The resin was washed
consecutively with 50% aq. ethanol (150 mL) and water (150 mL),
and the title compound was eluted with 3 % aq. ammonia
(250 mL). The title compound was obtained by reverse-phase pre-
parative HPLC as a white amorphous solid in a 64% yield (0.33 g,
1
1.44 mmol). H NMR, 13C NMR, IR, and HRMS-ESI data were
identical to those of enantiomeric compound 29. [α]20 = –85 (c =
H2O).1H NMR (500.0 MHz, D2O, 25 °C): δ = 3.46 (dd, Jgem
13.6, J2Јb,3Ј = 1.4 Hz, 1 H, 2Јb-H), 3.61 (ddd, Jgem = 13.6, J2Јa,3Ј
=
=
0.247, H2O).
Eur. J. Org. Chem. 2011, 2172–2187
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2183

D. Rejman et al.
FULL PAPER
3.2, J2Јa,6Јb = 1.9 Hz, 1 H, 2Јa-H), 3.78 (ddd, Jgem = 12.8, J6Јb,5Ј
5.4, J6Јb,2Јa = 1.9 Hz, 1 H, 6Јb-H), 3.84 (dd, Jgem = 12.8, J6Јa,5Ј
=
=
was added to a solution of 48 (2.99 g, 7.98 mmol) in DMF (80 mL)
and the reaction mixture was stirred first at r.t. for 4 h and then
12.1 Hz, 1 H, 6Јa-H), 4.44 (ddd, J3Ј,2Јa = 3.2, 1.4, J3Ј,4Ј = 2.9 Hz, 1 at 120 °C overnight. The solvent was removed in vacuo and the
H, 3Ј-H), 4.60 (dd, J4Ј,5Ј = 10.7, J4Ј,3Ј = 2.9 Hz, 1 H, 4Ј-H), 5.15
(td, J5Ј,6Ј = 12.1, 5.4, J5Ј,4Ј = 10.7 Hz, 1 H, 5Ј-H), 8.45 (s, 2 H, 2,8-
H) ppm. 13C NMR (125.7 MHz, D2O, 25 °C): δ = 47.05 (CH2-6Ј),
chloroguanine intermediate 49 was obtained by chromatography on
silica gel using a linear gradient of ethanol in chloroform; yield
67 % (2.06 g, 5.35 mmol); brownish amorphous solid. 1H NMR
51.06 (CH2-2Ј), 54.96 (CH-5Ј), 68.43 (CH-3Ј), 71.60 (CH-4Ј), (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.43 [s, 9 H, (CH3)3C], 3.32
121.49 (C-5), 146.63 (CH-8), 147.00 (CH-2), 151.68 (C-4), 152.69 (dd, Jgem = 12.9, J6Јb,5Ј = 11.1 Hz, 1 H, 6Јb-H), 3.06 (dd, Jgem
(C-6) ppm. IR (KBr): ν = 3401 (s, br.), 3333 (s, br.), 3210 (s, 13.8, J2Јb,3Ј = 1.7 Hz, 1 H, 2Јb-H), 4.44 (ddd, J3Ј,4Ј = 3.0, J3Ј,2Ј
=
=
˜
max
br.), 2935 (m, br.), 2700 (w, br., sh), 1642.9 (vs), 1600 (s), 1574 (m),
1505 (w), 1476 (m), 1415 (m), 1371 (w), 1330 (m), 1304 (m), 1207
(w), 1091 (m), 798 (w), 727 (w), 705 (w), 650 (m) cm–1. HRMS-
3.5, 1.7 Hz, 1 H, 3Ј-H), 4.22 (ddd, Jgem = 13.8, J2Јa,3Ј = 3.5, J2Јa,6Јa
= 2.2 Hz, 1 H, 2Јa-H), 4.13 (ddd, Jgem = 12.9, J6Јa,5Ј = 4.8, J6Јa,2Јa
= 2.2 Hz, 1 H, 6Јa-H), 4.18 (dd, J4Ј,5Ј = 10.7, J4Ј,3Ј = 3.0 Hz, 1 H,
FAB: calcd. for C10H15O2N6 [M + H]+ 251.12510; found 4Ј-H), 4.56 (ddd, J5Ј,6Ј = 11.1, 4.8, J5Ј,4Ј = 10.7 Hz, 1 H, 5Ј-H), 4.60
251.12519.
(br. s, 2 H, OH-3Ј,5Ј), 6.43 (br. s, 2 H, NH2), 8.10 (s, 1 H, 8-
H) ppm. 13C NMR (125.7 MHz, [D6]DMSO, 100 °C): δ = 27.82
[(CH3)3C], 45.18 (CH2-2Ј), 47.99 (CH2-6Ј), 52.74 (CH-5Ј), 67.28
(CH-3Ј), 70.20 (CH-4Ј), 78.81 [C(CH3)3], 123.70 (C-5), 141.87 (CH-
8), 149.20 (C-6), 154.33, 154.39 (C-4, CO), 159.25 (C-2) ppm. IR
(3R,4S,5R)-9-(3,4-Dihydroxypiperidin-5-yl)-6-oxopurine (46): Chlo-
ropurine derivative 44 (0.28 g, 0.76 mmol) in 3 m HCl (10 mL) was
stirred at 90 °C overnight. The reaction mixture was then diluted
with water (40 mL) and applied onto a column of Dowex 50 H+
ion exchange resin, which was washed consecutively with 50% aq.
ethanol (200 mL) and water (100 mL), and the title compound was
eluted with 3% aq. ammonia. After solvent evaporation, 46 (78%,
0.15 g, 0.593 mmol) was obtained as a white amorphous solid.
(KBr): ν
= 3494 (br. m, sh), 3385 (s), 3219 (m), 2976 (m), 2931
˜
max
(w), 1693 (s, sh), 1679 (s), 1612 (vs), 1566 (s), 1514 (m), 1467 (s),
1428 (s), 1407 (s), 1395 (s, sh), 1367 (s), 1319 (w, sh), 1280 (m, sh),
1263 (m), 1247 (m), 1199 (m), 1166 (s), 1001 (w), 863 (w), 784 (w),
764 (w), 640 (w) cm–1. HRMS-ESI: calcd. for C15H22O4N6Cl [M +
H]+ 385.13856; found 385.13860.
[α]20 = –54 (c = 0.165, H2O). H NMR (500.0 MHz, D2O, 25 °C):
1
δ = 3.37 (dd, Jgem = 14.2, J2Јb,3Ј = 0.9 Hz, 1 H, 2Јb-H), 3.53 (dd,
Jgem = 14.2, J2Јa,3Ј = 3.5 Hz, 1 H, 2Јa-H), 3.78 (m, 2 H, 6Ј-H), 4.39
(3R,4S,5R)-9-(3,4-Dihydroxypiperidin-5-yl)guanine (50): Com-
pound 49 (2.06 g, 5.35 mmol) was treated with 1.5 m HCl (40 mL)
at 75 °C overnight. The reaction mixture was diluted with water
(40 mL) and applied onto a column of Dowex 50 H+ ion exchange
resin (50 mL), which was washed consecutively with 50% aq. eth-
anol (200 mL) and water (300 mL), and the title compound was
eluted with 3% aq. ammonia (400 mL). After evaporation of sol-
vents, the obtained yellowish solid was suspended in a hot water/
ethanol mixture (2:1, 50 mL), cooled down, and filtered. The de-
sired compound was obtained in 95% yield (1.35 g, 5.08 mmol) as
a beige amorphous powder. [α]20 = –43 (c = 0.309, H2O). 1H NMR
(br. dd, J3Ј,2Јa = 3.5, J3Ј,4Ј = 2.9 Hz, 1 H, 3Ј-H), 4.54 (dd, J4Ј,5Ј
10.7, J4Ј,3Ј = 2.9 Hz, 1 H, 4Ј-H), 5.02 (td, J5Ј,6Ј = 10.7, 6.5, J5Ј,4Ј
10.7 Hz, 1 H, 5Ј-H), 8.19 (s, 1 H, 2-H), 8.22 (s, 1 H, 8-H) ppm. 13
=
=
C
NMR (125.7 MHz, D2O, 25 °C): δ = 47.70 (CH2-6Ј), 51.10 (CH2-
2Ј), 55.06 (CH-5Ј), 68.89 (CH-3Ј), 71.98 (CH-4Ј), 126.56 (C-5),
143.80 (CH-8), 148.47 (CH-2), 151.94 (C-4), 161.34 (C-6) ppm. IR
(KBr): νmax = 3424 (vs, br.), 1694 (s), 1637 (m, br.), 1587 (m), 1517
˜
(w), 1418 (w), 1346 (w), 1216 (w), 1150 (w), 1093 (w), 1010 (w),
788 (w), 647 (w) cm–1. HRMS-ESI: calcd. for C10H14O3N5 [M +
H]+ 252.10912; found 252.10911.
(500.0 MHz, D2O, 25 °C): δ = 3.42 (dd, Jgem = 13.6, J2Јb,3Ј
1.5 Hz, 1 H, 2Јb-H), 3.59 (ddd, Jgem = 13.6, J2Јa,3Ј = 3.3, J2Јa,6Ј
=
=
(3R,4S,5R)-5-[(2,5-Diamino-6-chloropyrimidin-4-yl)amino]-1-(tert-
butoxycarbonyl)-3,4-dihydroxypiperidine (48): A mixture of amine
39a (2.44 g, 10.5 mmol), 2,5-diamino-4,6-dichloropyrimidine
(3.76 g, 21 mmol), and triethylamine (7.3 mL, 52.5 mmol) in n-bu-
tanol (80 mL) was stirred in a pressure vessel at 135 °C overnight.
The solvent was removed in vacuo and the title compound was
recovered by chromatography on silica gel using a linear gradient of
ethanol in chloroform; yield 76% (2.99 g, 7.98 mmol); light-brown
1.5 Hz, 1 H, 2Јa-H), 3.79 (m, 2 H, 6Ј-H), 4.43 (m, 1 H, 3Ј-H), 4.58
(dd, J4Ј,5Ј = 10.6, J4Ј,3Ј = 2.9 Hz, 1 H, 4Ј-H), 5.02 (td, J5Ј,6Ј = 10.6,
6.1, J5Ј,4Ј = 10.6 Hz, 1 H, 5Ј-H), 8.69 (s, 1 H, 8-H) ppm. 13C NMR
(125.7 MHz, D2O, 25 °C): δ = 46.60 (CH2-6Ј), 50.97 (CH2-2Ј),
55.50 (CH-5Ј), 68.34 (CH-3Ј), 71.03 (CH-4Ј), 113.38 (C-5), 140.34
(CH-8), 153.69 (C-4), 157.51 (C-2), 159.03 (C-6) ppm. IR (KBr):
ν
max = 3394 (m), 3287 (m), 3241 (m), 3183 (m), 3003 (m), 2831 (m),
˜
2793 (m), 2735 (m), 2684 (m), 2625 (w), 2552 (w), 1716 (vs), 1685
(w, sh), 1643 (vs), 1603 (m), 1560 (w), 1537 (w), 1400 (m), 1380
(m), 1091 (w), 1073 (w), 793 (w), 689 (w) cm–1. HRMS-ESI: calcd.
for C10H15O3N6 [M + H]+ 267.12001; found 267.12004.
1
foam. H NMR (500.0 MHz, [D6]DMSO, 80 °C): δ = 1.37 [s, 9 H,
(CH3)3C], 3.05 (br. m, 1 H, 6Јb-H), 3.21 (br. d, Jgem = 12.6 Hz, 1
H, 2Јb-H), 3.53 (m, 1 H, 2Јa-H), 3.64 (dd, J4Ј,5Ј = 8.1, J4Ј,3Ј
=
2.9 Hz, 1 H, 4Ј-H), 3.74 (br. d, Jgem = 13.3 Hz, 1 H, 6Јa-H), 3.82
(dt, J3Ј,2Ј = 6.1, 2.9, J3Ј,4Ј = 2.9 Hz, 1 H, 3Ј-H), 4.13 (m, J5Ј,4Ј = 8.1,
J5Ј,NH = 7.6, J5Ј,6Ј = 6.8, 4.3 Hz, 1 H, 5Ј-H), 4.43, 5.37 (2 ϫbr. s,
2ϫ2 H, NH2), 6.03 (br. d, JNH,5Ј = 7.6 Hz, 1 H, NH-5Ј) ppm. 13C
NMR (125.7 MHz, [D6]DMSO, 80 °C): δ = 27.92 [(CH3)3C], 45.75
(CH2-6Ј), 46.46 (CH2-2Ј), 49.89 (CH-5Ј), 66.16 (CH-3Ј), 70.98
(CH-4Ј), 78.37 [C(CH3)3], 113.38 (C-5), 141.72 (C-6), 154.38 (CO),
(3S,4R,5R)-1-(tert-Butoxycarbonyl)-3,5-dihydroxy-4-[3-(3-ethoxy-
acryloyl)ureido]piperidine (51): 4-Nitrophenyl (3-ethoxyacryloyl)-
carbamate (0.58 g, 2.1 mmol) was added to a solution of amino
derivative 39b (0.73 g, 3.14 mmol) in dioxane (40 mL). The reaction
mixture was stirred at r.t. for 4 h, and the solvent was removed in
vacuo. The title compound was obtained by chromatography on
silica gel using a linear gradient of ethanol in chloroform; yield
72% (0.84 g, 2.25 mmol); yellowish foam. 1H NMR (500.0 MHz,
[D6]DMSO, 100 °C): δ = 1.28 (t, Jvic = 7.0 Hz, 3 H, CH3CH2O),
155.45, 155.51 (C-2,4) ppm. IR (CHCl ): νmax = 3532 (w, sh), 3501
˜
3
(w), 3420 (m, sh), 3395 (m), 3330 (br. m, sh), 3220 (w, br., sh), 2980
(s), 2574 (w, br.), 2453 (w, br.), 1686 (s), 1610 (s), 1570 (vs), 1504
(m), 1473 (s, sh), 1455 (s), 1431 (s), 1393 (m), 1368 (m), 1347 (w,
sh), 1248 (s), 1164 (s), 1111 (m), 1092 (m) cm–1. HRMS-ESI: calcd.
for C14H24O4N6Cl [M + H]+ 375.15421; found 375.15430.
1.42 {s, 9 H, [(CH3)3C]}, 2.58 (dd, Jgem = 12.6, J2Јb,3Ј&6Јb,5Ј
=
9.4 Hz, 2 H, 2Јb,6Јb-H), 3.31–3.41 (m, 3 H, 3Ј,4Ј,5Ј-H), 3.96 (m, 2
H, 2Јa,6Јa-H), 3.99 (q, Jvic = 7.0 Hz, 2 H, CH3CH2O), 4.93 (br. d,
JOH,3Ј&OH,5Ј = 4.3 Hz, 2 H, OH-3Ј,5Ј), 5.58 (d, Jvic = 12.3 Hz, 1 H,
5-H), 7.55 (d, Jvic = 12.3 Hz, 1 H, 6-H), 8.53 (d, JNH,4Ј = 6.3 Hz,
1 H, NH-1), 9.68 (br. s, 1 H, NH-3) ppm. 13C NMR (125.7 MHz,
(3R,4S,5R)-1-(tert-Butoxycarbonyl)-6-chloro-9-(3,4-dihydroxypiper-
idin-5-yl)purine (49): Diethoxymethyl acetate (1.43 mL, 8.78 mmol)
2184
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2172–2187

Dihydroxypiperidinyl Derivates of Nucleobases
[D6]DMSO, 100 °C): δ = 13.96 (CH3CH2O), 27.80 [(CH3)3C], 48.78
(3S,4R,5R)-9-(3,5-Dihydroxypiperidin-4-yl)adenine (54): Diethoxy-
(CH2-2Ј,6Ј), 60.91 (CH-4Ј), 67.06 (CH3CH2O), 67.72 (CH-3Ј,5Ј), methyl acetate (0.2 mL, 1.3 mmol) was added to a solution of 53
78.82 [C(CH3)3], 98.68 (CH-5), 153.65 (CO), 154.59 (C-2), 161.44 (0.33 g, 0.92 mmol) in DMF (12 mL). The reaction mixture was
(CH-6), 167.42 (C-4) ppm. IR (KBr): ν = 3404 (m, v br.), 3333 stirred at r.t. for 2 h and then at 110 °C overnight. The solvent was
˜
max
(br. m, sh), 3259 (m, br.), 3220 (br. m, sh), 3112 (m, br.), 3095 (w, removed in vacuo and the chloroguanine intermediate was purified
br., sh), 2982 (m), 1698 (vs), 1676 (vs), 1632 (m, sh), 1605 (s), 1562 by chromatography on silica gel using a linear gradient of ethanol
(s), 1498 (w), 1478 (m), 1466 (m), 1420 (m), 1394 (m), 1366 (m), in chloroform. Concentrated aq. ammonia (20 mL) was added and
1247 (s), 1183 (s), 1150 (s), 1135 (s), 1072 (m), 1055 (m), 1014 (m), the reaction mixture was stirred at room temp. for 3 d. The reaction
984 (w), 957 (w) cm–1. HRMS-ESI: calcd. for C16H27O7N3Na [M mixture was concentrated in vacuo, then 3 m HCl (30 mL) was
+ Na]+ 396.1741; found 396.1743.
added and the reaction mixture was stirred at 80 °C overnight. The
reaction mixture was diluted with water (40 mL) and applied onto
a column of Dowex 50 (H+) ion exchange resin, which was washed
consecutively with 50% aq. ethanol (200 mL) and water (100 mL),
and the title compound was eluted with 3% aq. ammonia. The
pure substance was purified by reverse-phase preparative HPLC as
a white amorphous solid in a yield of 49% (113 mg, 0.45 mmol).
(3S,4R,5R)-1-(3,5-Dihydroxypiperidin-4-yl)uracil (52): A mixture of
compound 51 (0.56 g, 1.5 mmol) and Dowex 50 (H+) ion exchange
resin (7 g) in dioxane (25 mL) was stirred at 90 °C for 3 h. The
resin was washed consecutively with 50% aq. ethanol (150 mL) and
water (150 mL), and the title compound was eluted with 3% aq.
ammonia (250 mL). The title compound was obtained by reverse-
phase preparative HPLC in a yield of 81% (276 mg, 1.21 mmol) as
a white amorphous solid. [α]20 = 0 (c = 0.217, H2O). 1H NMR
(500.0 MHz, MeOD, –80 °C): δ (conformation A) = 2.50 (dd, Jgem
= 11.5, J2Јax,3Ј = J6Јax,5Ј = 10.2 Hz, 2 H, 2Јax,6Јax-H), 3.16 (m, 2
1
[α]20 = 0 (c = 0.279, H2O). H NMR (600.1 MHz, D2O, 28 °C): δ
= 2.62 (dd, Jgem = 12.8, J2Јb,3Ј&6Јb,5Ј = 10.3 Hz, 2 H, 2Јb,6Јb-H),
3.32 (dd, Jgem = 12.8, J2Јa,3Ј&6Јa,5Ј = 4.8 Hz, 2 H, 2Јa,6Јa-H), 4.22
(t, J4Ј,3Ј = J4Ј,5Ј = 10.0 Hz, 1 H, 4Ј-H), 4.27 (ddd, J3Ј,2Јb&5Ј,6Јb
=
10.3, J3Ј&5Ј,4Ј = 10.0, J3Ј,2Јa&5Ј,6Јa = 4.8 Hz, 2 H, 3Ј,5Ј-H), 8.21 (s, 1
H, 2-H), 8.26 (s, 1 H, 8-H) ppm. 13C NMR (150.9 MHz, D2O,
28 °C): δ = 52.69 (CH2-2Ј,6Ј), 69.26 (CH-4Ј), 71.07 (CH-3Ј,5Ј),
121.63 (C-5), 144.21 (CH-8), 152.46 (C-4), 155.23 (CH-2), 158.40
H, 2Јeq,6Јeq-H), 3.64 (ddd, J3Ј,4Ј = J5Ј,4Ј = 10.3, J3Ј,2Јax = J5Ј,6Јax
10.2, J3Ј,2Јeq = J5Ј,6Јeq = 5.3 Hz, 2 H, 3Ј-H, 5Ј-H), 4.44 (t, J4Ј,3Ј
=
=
J4Ј,5Ј = 10.3 Hz, 1 H, 4Ј-H), 5.82 (d, J5,6 = 8.2 Hz, 1 H, 5-H), 7.88
(d, J6,5 = 8.2 Hz, 1 H, 6-H) ppm; δ (conformation B) = 2.40 (dd,
Jgem = 11.4, J2Јax,3Ј = J6Јax,5Ј = 10.0, 2 H, H-2Јax,6Јax), 3.16 (m, 2
H, H-2Јeq,6Јeq), 3.24 (t, J4Ј,3Ј = J4Ј,5Ј = 10.0, 1 H, H-4Ј), 4.51 (td,
J3Ј,4Ј = J5Ј,4Ј = J3Ј,2Јax = J5Ј,6Јax = 10.0, J3Ј,2Јeq = J5Ј,6Јeq = 5.3, 2 H,
H-3Ј, H-5Ј), 5.63 (d, J5,6 = 8.0, 1 H, H-5), 7.50 (d, J6,5 = 8.1, 1 H,
H-6) ppm. 13C NMR (125.7 MHz, MeOD, –80 °C): δ (conforma-
tion A) = 52.06 (CH2-2Ј,6Ј), 65.70 (CH2-4Ј), 69.13 (CH-3Ј,5Ј),
102.83 (CH-5), 142.99 (CH-6), 154.06 (C-2), 166.58 (C-4) ppm; δ
(conformation B) = 51.84 (CH2-2Ј,6Ј), 66.27 (CH2-3Ј,5Ј), 79.11
(CH-4Ј), 100.94 (CH-5), 151.19 (CH-6), 152.33 (C-2), 167.44 (C-
(C-6) ppm. IR (KBr): νmax = 3345 (s, br.), 2981 (m), 1751 (w), 1770
˜
(w, sh), 1697 (vs), 1646 (m), 1608 (m), 1571 (m), 1550 (w), 1515
(w), 1479 (m), 1468 (m), 1424 (s), 1390 (m, sh), 1367 (s), 1340 (m,
sh), 1308 (m), 1259 (s), 1235 (s), 1220 (s, sh), 1173 (s), 1162 (s),
1083 (m), 1072 (m), 1023 (m), 856 (w), 794 (w), 787 (w), 765 (w),
650 (m) cm–1. HRMS-ESI: calcd. for C10H13O3N6 (M – H)–
249.1100; found 249.1097.
(3S,4R,5R)-4-[(2,5-Diamino-6-chloropyrimidin-4-yl)amino]-1-(tert-
butoxycarbonyl)-3,5-dihydroxypiperidine (55): A mixture of amine
39b (0.57 g, 2.45 mmol), 2,5-diamino-4,6-dichloropyrimidine
(0.88 g, 4.9 mmol), and triethylamine (1.7 mL, 12.25 mmol) in n-
butanol (25 mL) was stirred in a pressure vessel at 135 °C over-
night. The solvent was removed in vacuo and the title compound
was purified by chromatography on silica gel using a linear gradient
of ethanol in chloroform; yield 47% (0.43 g, 1.15 mmol); brown
foam. 1H NMR (500.0 MHz, [D6]DMSO, 100 °C): δ = 1.44 {s, 9
H, [(CH3)3C]}, 2.68 (dd, Jgem = 13.0, J2Јb,3Ј&6Јb,5Ј = 10.3 Hz, 2 H,
2Јb,6Јb-H), 3.47 (ddd, J3Ј,2Ј&5Ј,6Ј = 10.3, 5.0, J3Ј,4Ј&5Ј,4Ј = 9.1 Hz, 2
H, 3Ј,5Ј-H), 3.76 (td, J4Ј,3Ј = J4Ј,5Ј = 9.1, J4Ј,NH = 6.8 Hz, 1 H, 4Ј-
H), 4.00 (m, 2 H, 2Јa,6Јa-H), 4.88, 4.99, 5.33 (3 ϫbr. s, 3ϫH, OH-
3Ј,5Ј, NH2), 6.17 (br. d, JNH,4Ј = 6.8 Hz, 1 H, NH) ppm. 13C NMR
(125.7 MHz, [D6]DMSO, 100 °C): δ = 27.82 [(CH3)3C], 48.81
(CH2-2Ј,6Ј), 61.70 (CH-4Ј), 68.46 (CH-3Ј,5Ј), 78.78 [C(CH3)3],
113.10 (C-5), 140.07 (C-6), 153.71 (CO), 155.06, 156.80 (C-
4) ppm. IR (KBr):ν
= 3396 (m, br.), 3313 (br. m, sh), 3187 (br.
˜
max
m, sh), 2826 (w, v br.), 1682 (vs, br.), 1630 (m, sh), 1463 (m), 1385
(m), 1262 (m), 1083 (w), 1052 (m), 1017 (w), 811 (w), 766 (w), 719
(vw) cm–1. HRMS-ESI: calcd. for C9H14O4N3 [M + H]+ 228.0979;
found 228.0978.
(3S,4R,5R)-4-[(5-Amino-6-chloropyrimidin-4-yl)amino]-1-(tert-
butoxycarbonyl)-3,5-dihydroxypiperidine (53): A mixture of amine
39b (0.35 g, 1.5 mmol), 3-amino-4,6-dichloropyrimidine (0.5 g,
3 mmol), and triethylamine (0.9 mL, 6.45 mmol) in n-butanol
(15 mL) was stirred in a pressure vessel at 130 °C for 3 d. The sol-
vent was removed in vacuo, and purified by preparative chromatog-
raphy on silica gel using a linear gradient of ethanol in chloroform
to provide the title compound in 61% yield (330 mg, 0.917 mmol)
1
as a brown foam. H NMR (500.0 MHz, [D6]DMSO, 100 °C): δ =
2,4) ppm. IR (KBr): ν
= 3419 (vs, br.), 2977 (w), 1697 (s), 1642
˜
max
1.44 {s, 9 H, [(CH3)3C]}, 2.68 (dd, Jgem = 13.0, J2Јb,3Ј&6Јb,5Ј
10.2 Hz, 2 H, 2Јb,6Јb-H), 3.52 (ddd, J3Ј,2Ј&5Ј,6Ј = 10.2, 5.3,
J3Ј,4Ј&5Ј,4Ј = 9.3 Hz, 2 H, 3Ј,5Ј-H), 3.92 (td, J4Ј,3Ј = J4Ј,5Ј = 9.3,
=
(s, sh), 1635 (s, sh), 1623 (s), 1575 (s), 1501 (m), 1475 (m, sh), 1464
(m), 1455 (m, sh), 1425 (s), 1393 (m, sh), 1367 (m), 1346 (w), 1306
(w), 1257 (m), 1235 (m), 1165 (m), 1151 (m), 1102 (w, sh), 1092 (w),
869 (vw), 771 (w) cm–1. HRMS (ESI): calcd. for C14H24O4N6Cl [M
+ H]+ 375.15421; found 375.15428.
J4Ј,NH = 7.6 Hz, 1 H, 4Ј-H), 4.01 (dd, Jgem = 13.0, J2Јa,3Ј&6Јa,5Ј
=
5.3 Hz, 2 H, 2Јa,6Јa-H), 4.73 (br. s, 4 H, OH-3Ј,5Ј, NH2), 6.38 (br.
d, JNH,4Ј = 7.6 Hz, 1 H, NH), 7.71 (s, 1 H, 2-H) ppm. 13C NMR
(125.7 MHz, [D6]DMSO, 100 °C): δ = 27.81 [(CH3)3C], 48.85
(3S,4R,5R)-9-(3,5-Dihydroxypiperidin-4-yl)guanine (56): Diethoxy-
(CH2-2Ј,6Ј), 61.75 (CH-4Ј), 68.12 (CH-3Ј,5Ј), 78.77 [C(CH3)3], methyl acetate (0.2 mL, 1.3 mmol) was added to a solution of 55
123.16 (C-5), 137.57 (C-6), 145.16 (CH-2), 153.50 (C-4), 153.77 (0.43 g, 1.15 mmol) in DMF (12 mL). The reaction mixture was
(CO) ppm. IR (KBr): νmax = 3420 (br. s, sh), 3369 (s, br.), 3262 (m,
stirred at r.t. for 2 h and then at 110 °C overnight. The solvent was
br.), 2977 (m), 2710 (w, br., sh), 1697 (s), 1668 (s), 1584 (vs), 1496 removed in vacuo and the chloroguanine intermediate was purified
(m, sh), 1479 (m, sh), 1466 (s), 1423 (s), 1395 (m), 1368 (m), 1340 by chromatography on silica gel using a linear gradient of ethanol
˜
(m), 1240 (m), 1217 (m), 1165 (s), 1138 (m), 1072 (m, sh), 1050 in chloroform. Without further characterization, at this point, it
(m, sh), 1016 (m), 850 (w), 768 (w) cm–1. HRMS-FAB: calcd. for
C14H23O4N5Cl [M + H]+ 360.1433; found 360.1428.
was treated with 1.5 m HCl (20 mL) at 75 °C overnight. The reac-
tion mixture was diluted with water (40 mL) and applied onto a
Eur. J. Org. Chem. 2011, 2172–2187
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2185

D. Rejman et al.
FULL PAPER
column of Dowex 50 (H+) ion exchange resin (40 mL), which was
washed consecutively with 50% aq. ethanol (100 mL) and water
(200 mL), and the title compound was eluted with 3% aq. ammo-
nia (200 mL). The obtained yellowish solid was suspended in a hot
water/ethanol mixture (2:1), which was then cooled and filtered.
The desired compound was obtained in 71% (220 mg, 0.826 mmol)
overall yield as a beige amorphous powder. [α]20 = 0 (c = 0.071,
(m), 1005 (m) cm–1. HRMS-ESI: calcd. for C7H15O3N2 [M + H]+
175.10772; found 175.10765.
(3S,4R,5R)-N-(3,5-Dihydroxypiperidin-4-yl)acetamide (59): Acetic
anhydride (0.19 mL, 1.85 mmol) was added to a mixture of 39b
(0.43 g, 1.85 mmol) and NaHCO3 (0.17 g, 2 mmol) in ethanol
(20 mL). The reaction mixture was stirred at r.t. for 3 h, then the
solvent was removed in vacuo and the acetylated intermediate was
purified as a white foam by chromatography on silica gel using a
linear gradient of ethanol in chloroform. Without further charac-
terization, the intermediate was dissolved in 20% TFA in CH2Cl2
(25 mL) and stirred at r.t. overnight. The solvent was removed in
vacuo and the residue was co-evaporated with a 1:1 ethanol/toluene
mixture (3ϫ20 mL). The residue was dissolved in water and passed
through a column of Dowex 1 (Cl–) ion exchange resin (50 mL).
After removal of the solvents in vacuo, compound 59 was obtained
in 97% yield (0.38 g, 1.8 mmol) as a white amorphous solid. 1H
NMR (500.0 MHz, [D6]DMSO, 25 °C): δ = 1.84 (s, 3 H, CH3), 2.66
(br. m, 2 H, 2b,6b-H), 3.15 (br. dd, Jgem = 12.3, J2a,3&6a,5 = 4.6 Hz,
2 H, 2a,6a-H), 3.55 (td, J4,3 = J4,5 = 9.4, J4,NH = 8.4 Hz, 1 H, 4-
H), 3.65 (ddd, J3,2b&5,6b = 10.7, J3&5,4 = 9.4, J3,2a&5,6a = 4.6 Hz, 2
H2O). 1H NMR (500.0 MHz, D2O, 25 °C): δ = 2.61 (dd, Jgem
12.6, J2Јb,3Ј&6Јb,5Ј = 10.7 Hz, 2 H, 2Јb,6Јb-H), 3.31 (dd, Jgem = 12.6,
J2Јa,3Ј&6Јa,5Ј = 4.8 Hz, 2 H, 2Јa,6Јa-H), 4.07 (t, J4Ј,3Ј = J4Ј,5Ј
=
=
10.3 Hz, 1 H, 4Ј-H), 4.21 (ddd, J3Ј,2Јb&5Ј,6Јb = 10.7, J3Ј&5Ј,4Ј = 10.3,
J3Ј,2Јa&5Ј,6Јa = 4.8 Hz, 2 H, 3Ј,5Ј-H), 7.94 (s, 1 H, 8-H) ppm. 13C
NMR (125.7 MHz, D2O, 25 °C): δ = 52.55 (CH2-2Ј,6Ј), 68.41 (CH-
4Ј), 70.89 (CH-3Ј,5Ј), 119.03 (C-5), 141.37 (CH-8), 155.46 (C-4),
156.37 (C-2), 161.90 (C-6) ppm. IR (KBr): ν
= 3564 (w), 3460
˜
max
(m, sh), 3411 (m), 3320 (s), 3292 (s, sh), 3133 (m, br.), 2779 (w, v
br.), 1692 (vs), 1657 (m), 1622 (s), 1575 (m), 1535 (m), 1481 (m),
1416 (m), 1084 (m), 1045 (m), 779 (m), 643 (w) cm–1. HRMS-ESI:
calcd. for C10H15O3N6 [M + H]+ 267.12001; found 267.12002.
(3R,4R,5S)-N-(4,5-Dihydroxypiperidin-3-yl)acetamide (57): Acetic
anhydride (80 μL, 0.88 mmol) was added to a mixture of 26 (0.2 g,
0.73 mmol) and NaHCO3 (70 mg, 0.88 mmol) in ethanol (10 mL).
The reaction mixture was stirred at r.t. for 3 h, then the solvent was
removed in vacuo and the acetylated intermediate was purified by
chromatography on silica gel using a linear gradient of ethanol in
chloroform. Without further characterization, the intermediate was
dissolved in 20% TFA in CH2Cl2 (15 mL) and stirred at r.t. over-
night. The solvent was removed in vacuo and the residue was co-
evaporated with a 1:1 ethanol/toluene mixture (3ϫ20 mL) to af-
ford pure 57 in 80% (102 mg, 0.584 mmol) as a white amorphous
H, 3,5-H), 8.02 (d, JNH,4 = 8.4 Hz, 1 H, NH-4), 9.50 (br. d, Jgem
10.0 Hz, 1 H, NHb-1), 9.58 (br. q, Jgem = JNH,2b = JNH,6b
=
=
10.0 Hz, 1 H, NHa-1) ppm. 13C NMR (125.7 MHz, [D6]DMSO,
25 °C): δ = 23.25 (CH3), 47.16 (CH2-2,6), 58.16 (CH-4), 65.46 (CH-
3,5), 170.69 (CO) ppm. IR (KBr): ν
= 3454 (s, br.), 3350 (s),
˜
max
2968 (m, sh), 2939 (s), 2782 (s), 2725 (m), 2696 (m), 2675 (m), 2603
(w), 2566 (w), 2515 (w), 2475 (m), 2448 (w), 1617 (m), 1667 (vs),
1597 (w), 1567 (m, sh), 1549 (s), 1473 (w), 1459 (m), 1406 (w), 1365
(m), 1307 (m), 1091 (m), 1075 (w), 1042 (s), 632 (w), 599 (m), 588
(m) cm–1. HRMS-ESI: calcd. for C7H15O3N2 [M + H]+ 175.10772;
found 175.10759.
1
solid. H NMR (500.0 MHz, D2O, 28 °C): δ = 2.04 (s, 3 H, CH3),
3.17 (dd, Jgem = 12.7, J2b,3 = 9.4 Hz, 1 H, 2b-H), 3.18 (dd, Jgem
12.4, J6b,5 = 9.0 Hz, 1 H, 6b-H), 3.25 (dd, Jgem = 12.7, J2a,3
4.3 Hz, 1 H, 2a-H), 3.28 (dd, Jgem = 12.4, J6a,5 = 4.2 Hz, 1 H, 6a-
=
=
Calculations: The geometry optimization of both conformers of
compound 52 and the chemical shifts were calculated at the
B3LYP/6-311+G**/PCM level, with methanol used as the implicit
solvent as implemented in the Gaussian 09 program.[30]
H), 4.08 (dd, J4,3 = 3.1, J4,5 = 2.6 Hz, 1 H, 4-H), 4.10 (ddd, J5,6
9.0, 4.2, J5,4 = 2.6 Hz, 1 H, 5-H), 4.25 (ddd, J3,2 = 9.4, 4.3, J3,4
=
=
3.1 Hz, 1 H, 3-H) ppm. 13C NMR (125.7 MHz, D2O, 28 °C): δ =
Acknowledgments
24.68 (CH3), 44.32 (CH2-2), 46.22 (CH2–6), 49.12 (CH-3), 67.90
(CH-5), 69.57 (CH-4), 176.77 (CO) ppm. IR (KBr): ν
= 3402
˜
max
Support by the Ministry of Education, Youth and Sports of the
Czech Republic (grant numbers #2B06065 and LC06077, under
research project Z40550506) and by the Grant Agency of the Acad-
emy of Sciences of the Czech Republic through project
KJB400550903 is gratefully acknowledged. Dr Milan Kolárˇ (Trios,
s.r.o.) is thanked for antibacterial activity testing.
(vs, br.), 3280 (br. s, sh), 1648 (s, br.), 1542 (m, br.), 1376 (m), 1086
(w), 1071 (w), 993 (w) cm–1. HRMS-ESI: calcd. for C7H15O3N2 [M
+ H]+ 175.10772; found 175.10775.
(3R,4S,5R)-N-(4,5-Dihydroxypiperidin-3-yl)acetamide (58): Acetic
anhydride (0.11 mL, 1.2 mmol) was added to a mixture of 39a
(0.22 g, 1 mmol) and NaHCO3 (0.1 g, 1.2 mmol) in ethanol
(10 mL). The reaction mixture was stirred at r.t. for 3 h, then the
solvent was removed in vacuo and the acetylated intermediate was
purified as a white foam by chromatography on silica gel using a
linear gradient of ethanol in chloroform. Without further charac-
terization, the intermediate was dissolved in 20% TFA in CH2Cl2
(15 mL) and stirred at r.t. overnight. The solvent was removed in
vacuo and the residue was co-evaporated with a 1:1 ethanol/toluene
mixture (3ϫ20 mL) to afford the desired compound in 90% yield
(190 mg, 0.9 mmol) as a white amorphous solid. 1H NMR
[1] K. H. Altmann, S. M. Freier, U. Pieles, T. Winkler, Angew.
Chem. Int. Ed. Engl. 1994, 33, 1654–1657.
[2] A. Boto, D. Hernández, R. Hernández, Tetrahedron Lett. 2009,
50, 3974–3977; A. Boto, D. Hernández, R. Hernández, Eur. J.
Org. Chem. 2010, 3847–3857.
[3] N. B. Westwood, T. T. Walker, Tetrahedron 1998, 54, 13391–
13404.
[4] U. Chiacchio, E. Balestrieri, B. Macchi, D. Iannazzo, A. Pip-
erno, A. Rescifina, R. Romeo, M. Saglimbeni, M. T. Sciortino,
V. Valveri, A. Mastino, G. Romeo, J. Med. Chem. 2005, 48,
1389–94.
[5] E. J. Reist, D. E. Gueffroy, R. W. Blackford, L. Goodman, J.
Org. Chem. 1966, 31, 4025–4030.
[6] A. Lewandowicz, E. A. T. Ringia, L. Ting, K. Kim, P. C. Tyler,
G. B. Evans, O. V. Zubkova, S. Mee, G. F. Painter, D. H. Lenz,
R. H. Furneaux, V. L. Schramm, J. Biol. Chem. 2005, 280,
30320–30328.
(500.0 MHz, D2O, 28 °C): δ = 2.02 (s, 3 H, CH3), 2.88 (dd, Jgem
12.8, J2b,3 = 12.0 Hz, 1 H, 2b-H), 3.21 (dd, Jgem = 13.7, J6b,5
=
=
1.6 Hz, 1 H, 6b-H), 3.45 (m, 1 H, 6a-H), 3.46 (m, 1 H, 2a-H), 3.80
(dd, J4,3 = 10.5, J4,5 = 3.0 Hz, 1 H, 4-H), 4.27 (td, J5,4 = 3.0, J5,6
= 3.0, 1.6 Hz, 1 H, 5-H), 4.32 (ddd, J3,2 = 12.0, 4.8, J3,4 = 10.5 Hz,
1 H, 3-H) ppm. 13C NMR (125.7 MHz, D2O, 28 °C): δ = 24.74
(CH3), 47.44 (CH2), 47.99 (CH-3), 50.63 (CH2-6), 68.22 (CH-5),
72.48 (CH-4), 177.46 (CO) ppm. IR (KBr): ν
= 3456 (s), 3322
˜
[7] K. Clinch, G. B. Evans, R. F. G. Fröhlich, R. H. Furneaux,
P. M. Kelly, L. Legentil, A. S. Murkin, L. Li, V. L. Schramm,
max
(vs), 1659 (vs), 1640 (m, sh), 1564 (s, sh), 1546 (vs), 1377 (m), 1097
2186
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2172–2187

Dihydroxypiperidinyl Derivates of Nucleobases
P. C. Tyler, A. D. Woolhouse, J. Med. Chem. 2009, 52, 1126–
43.
[8] V. Vaneˇk, M. Budeˇsˇínský, M. Rinnová, I. Rosenberg, Tetrahe-
dron 2009, 65, 862–876.
[9] P. Kocˇalka, R. Pohl, D. Rejman, I. Rosenberg, Tetrahedron
2006, 62, 5763–5774.
[10] D. Rejman, P. Kocˇalka, M. Budeˇsˇínský, R. Pohl, I. Rosenberg,
Tetrahedron 2007, 63, 1243–1253.
[23]
[24]
[25]
[26]
D. Rejman, S. Kovacˇková, R. Pohl, M. Dracˇínský, P. Fiedler,
I. Rosenberg, Tetrahedron 2009, 65, 8513–8523.
A. F. Abdel-Magid, K. G. Carson, B. D. Harris, C. Maryanoff,
R. D. Shah, J. Org. Chem. 1996, 61, 3849–3862.
H. Hrˇebabecký, M. Masojídková, A. Holý, Collect. Czech.
Chem. Commun. 2005, 70, 519–537.
R. G. Bhushan, R. Vince, Bioorg. Med. Chem. 2002, 10, 2325–
2333.
[11] D. Rejman, R. Pohl, P. Kocˇalka, M. Masojídková, I. Rosen-
berg, Tetrahedron 2009, 65, 3673–3681.
[27] R. C. Bernotas, B. Ganem, Carbohydr. Res. 1987, 167, 312–316.
[28] I. B. Parr, B. A. Horenstein, J. Org. Chem. 1997, 62, 7489–7494.
[29] S. Hanessian, T. H. Haskell, J. Org. Chem. 1963, 28, 2604–
2610.
[12] D. Rejman, P. Kocˇalka, R. Pohl, Z. Tocˇík, I. Rosenberg, Col-
lect. Czech. Chem. Commun. 2009, 74, 935–955.
[13] P. Kocˇalka, D. Rejman, V. Vanˇek, M. Rinnová, I. Tomecˇková,
ˇ
[30] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B.
Mennucci, G. A. Petersson, H. Nakatsuji, X. Caricato, X. Li,
H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Son-
nenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hase-
gawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai,
T. Vreven, J. Montgomery, J. A., J. E. Peralta, F. Ogliaro, M.
Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Starov-
erov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell,
J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M.
Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Ad-
amo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev,
A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Mar-
tin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B.
Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09,
Gaussian, Inc., Wallingford CT, 2009.
S. Králíková, M. Petrová, O. Páv, R. Pohl, M. Budeˇsˇínský, R.
Liboska, Z. Tocˇík, N. Panova, I. Votruba, I. Rosenberg, Bioorg.
Med. Chem. Lett. 2010, 20, 862–865.
[14] M. D. Sørensen, N. M. Khalifa, E. B. Pedersen, Synthesis 1999,
11, 1937–1943.
[15] D. Prukala, Tetrahedron Lett. 2006, 47, 9045–9047.
[16] P. Van Rompaey, K. A. Jacobson, A. S. Gross, Z. Gao, S.
Van Calenbergh, Bioorg. Med. Chem. 2005, 13, 973–983.
[17] S. Yang, R. Busson, P. Herdewijn, Tetrahedron 2008, 64,
10062–10067.
[18] K. Jung, K. Kim, M. Yang, K. Lee, H. Lim, Bioorg. Med.
Chem. Lett. 1999, 9, 3407–3410.
[19] P. S. Lonkar, V. Kumar, Bioorg. Med. Chem. Lett. 2004, 14,
2147–2149.
[20] S. Kovacˇková, M. Dracˇínský, D. Rejman, Tetrahedron 2011,
DOI: 10.1016/j.tet.2010.12.029.
[21] Y. Igarashi, M. I. Y. Ichikawa, Bioorg. Med. Chem. Lett. 1996,
Received: November 29, 2010
Published Online: March 1, 2011
6, 553–558.
[22] K. A. Watanabe, A. Matsuda, M. J. Halat, D. H. Hollenberg,
J. S. Nisselbaum, J. J. Fox, J. Med. Chem. 1981, 24, 893–897.
Eur. J. Org. Chem. 2011, 2172–2187
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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