Investigation, optimization and synthesis of sulfamoyloxy-linked aminoacyl-AMP analogues

Article abstract of DOI:10.1016/j.tet.2011.12.011

Aminoacyl-tRNA synthetases (aaRSs) constitute a family of enzymes that transfer amino acids to their corresponding tRNA molecules to form aminoacyl-tRNAs and have been validated as potential drug targets. Sulfamoyloxy-linked aminoacyl-AMP analogues are potent inhibitors of aaRSs. In this article, we report the synthesis of several new sulfamoyl analogues of aa-AMP that up to now have been difficult or even impossible to prepare with current synthetic strategies. The developed synthetic strategy relies on performing the synthesis under neutral conditions followed by global deprotection using catalytic hydrogenation affording the desired 5′-O-(N-aminoacyl)sulfamoyladenosine compounds.

Full text of DOI:10.1016/j.tet.2011.12.011

Tetrahedron 68 (2012) 1507e1514
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Investigation, optimization and synthesis of sulfamoyloxy-linked
aminoacyl-AMP analogues
*
Itedale Namro Redwan, Thomas Ljungdahl, Morten Grøtli
Department of Chemistry, Medicinal Chemistry, University of Gothenburg, 41296 Gothenburg, Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 October 2011
Received in revised form 14 November 2011
Accepted 6 December 2011
Available online 13 December 2011
Aminoacyl-tRNA synthetases (aaRSs) constitute a family of enzymes that transfer amino acids to their
corresponding tRNA molecules to form aminoacyl-tRNAs and have been validated as potential drug
targets. Sulfamoyloxy-linked aminoacyl-AMP analogues are potent inhibitors of aaRSs. In this article, we
report the synthesis of several new sulfamoyl analogues of aa-AMP that up to now have been difficult or
even impossible to prepare with current synthetic strategies. The developed synthetic strategy relies on
performing the synthesis under neutral conditions followed by global deprotection using catalytic hy-
drogenation affording the desired 50-O-(N-aminoacyl)sulfamoyladenosine compounds.
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Aminoacyl-tRNA synthetases
Sulfamoyloxy-linked aminoacyl-AMP
analogues
Amide bond formation
Catalytic hydrogenation
Protection group chemistry
1. Introduction
reaction intermediates, or have been identified by screening of
compound libraries. For example, the natural product mupirocin is
Aminoacyl-tRNA synthetases (aaRSs) are enzymes essential for
the viability of all living organisms because of their role in protein
biosynthesis.1 These enzymes are responsible for the ATP de-
pendent coupling of the correct amino acid to its cognate tRNA
through a two-step process (Scheme 1). The formation of an
enzyme-bound aminoacyl-adenylate monophosphate (aa-AMP) is
followed by the transfer of this activated amino acid to either the
20-or 30-hydroxy group of the adenosine moiety of tRNA.
used as an antibacterial drug in clinical applications (IleRS in-
hibitor),6 and REP8839, a bacterial MetRS inhibitor, is currently
under clinical investigation.7 Recently, an antifungal agent that
inactivates fungal LeuRS was reported8 and has now entered
clinical trials. Furthermore, aaRSs are considered as attractive drug
targets in disease pathogens such as mycobacteria, protozoans and
helminths.9
The design of most aa-AMP analogues reported so far has been
based on replacing the labile acyl-phosphate linkage of the in-
termediate with stable bioisosteres such as alkylphosphates,10e12
esters,13e15 amides,13 hydroxamates,13e15 sulfamates,10,11,16e19
sulfamides,11 N-alkoxysulfamides20 and N-hydroxysulfamides.20
We have designed and synthesised several non-hydrolysable
sulfamoyl analogues of aa-AMP that have been used by collabo-
rators in structural studies on a number of aaRSs.21e23 These
studies are possible as the analogue binding leads to stabilisation
of the active site, enables identification of the specific amino acid
binding pocket and contributes to the characterisation of the
conformational changes associated with aminoacyl-adenylate
formation. Such studies have been carried out on the aspar-
aginyl-21,22 and leucyl23-adenylate analogues leading to significant
new results.
Amino acid + ATP
aa-AMP + PPi
aa-AMP + tRNA aa-tRNA + AMP
Scheme 1. Schematic overview of the ATP dependent two-step process catalysed by
aaRSs resulting in the esterification of tRNA by its cognate amino acid.
AaRSs have emerged as an interesting target class for the de-
velopment of anti-infective drugs. When aaRS is inhibited, the
corresponding tRNA is not loaded and is therefore unavailable for
translation. Thus, inhibition of aaRS will halt protein synthesis and
attenuate microorganism growth.2e4 Various chemical structures
that inhibit aaRSs have been identified.5 In general, these in-
hibitors are based on the natural synthetase substrates and
Although sulfamoyl based analogues of aa-AMP are useful for
structural and biochemical studies of aaRSs and as potential lead
compounds for drug development, their synthesis is hampered by
* Corresponding author. Tel.: þ46 31 7869017; fax: þ46 31 7723840; e-mail ad-
dress: grotli@chem.gu.se (M. Grøtli).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.12.011

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I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
several limitations. The overall yields are highly dependent on the
amino acid and the protecting groups used in the synthesis and
consequently some sulfamoylated analogues of aa-AMP are difficult
to attain.
Herein, we report a novel synthetic strategy enabling the effi-
cient synthesis of several new sulfamoyl analogues of aa-AMP that
have been difficult to prepare up to now. The reported procedure
relies on an orthogonal protecting group strategy and global
deprotection under neutral conditions.
NH2
O
NH2
N
n
NH2
N
H
N
N
N
N
HX Q
O Y Z
O
Q
O Y Z
O
N
N
O
O
OH OH
4
OH OH
5
X = HN, O or S
Y = P or S
Z= -OH or =O
Q = HN or O
n = 1, 2 or 3
O
2. Results and discussion
H2N
X
2.1. Protective group strategy
n
6
A commonly used intermediate for the preparation of sulfa-
moylated analogues of aa-AMP is compound 1 (Fig 1) prepared
from 20,30-O-isopropylidene protected adenosine by sulfamoy-
lation.24 However, both 1 as well as derivatives with the general
structure 2 are prone to cyclonucleoside formation (3) (Fig. 1)
resulting in low yields of the desired products.25,26 A protecting
group strategy or synthetic procedure that minimizes or elimi-
nates this side-reaction is necessary to be able to increase the
yields in the synthesis of sulfamoylated analogues of aa-AMP.
Fig. 2. Lysyl-tRNA synthetase edits homocysteine by converting it into homocysteine
thiolactone. (X¼S, Y¼P, Z¼OH, Q¼O, n¼1). A similar intramolecular reaction could
potentially occur with synthetic derivatives of aa-AMP, derivatives (Q¼NH).
a benzylidene acetal protection group for the 20- and 30-hydroxy
functions of adenosine and a Cbz or benzyl (Bn) protective group of
the hetero functionality of the amino acid side chain would be an
excellent choice for the preparation of aa-AMP analogues. This
combination of protecting groups would enable global depro-
tection using catalytic hydrogenation.
NH2
NH2
N
2.2. Synthesis
R
N
N
N
N
N
NH
O S O
O
The synthesis of the target compounds is illustrated in
Scheme 2.
N
+
O
N
O
NH2
NHCbz
N
O
O
O
O
N
N
N
N
R
O
R
O
N
N
O
1 : R = H
2 : R =
3
N
O
NH2
O
i
iii
Adenosine
R'
O
O
O
O
Ph
8: R = Si(CH3)2C(CH3)3
Ph
Fig. 1. Compounds 1 and 2 are prone to cyclonucleoside (3) formation.
9: R = Si(CH3)2C(CH3)3
10: R = H
7: R = H
iv
v
ii
In our studies we also aimed to prepare sulfamoylated aa-
AMP analogues containing non-proteinogenic amino acids, e.g.,
homoserine and homocysteine. However, such aa-AMPs can
easily undergo intramolecular cyclisation reactions generating
lactone/thiolactone products (Fig. 2). It is believed that LysRS
edits homocysteine by such reactions (4, X¼S, Q¼O, Z¼OH,
n¼1).27 In principle, this reaction can occur with all derivatives
having an amino acid side chain with appropriate length (n¼1, 2
or 3) in combination with a nucleophilic heteroatom at the end
of the side chain (X¼NH, O or S). Furthermore, the cyclisation
reaction is most likely promoted by basic and acidic conditions,
respectively. Consequently, only protecting groups that are re-
moved under neutral conditions can be applied in the
protecting group strategy to avoid the formation of the cyclic
byproducts (6).
The synthesis of compounds 1 and 2 does not require protection
of the exocyclic amino function of the adenine moiety,24 but these
compounds are rather polar and the recovery after column chro-
matography can be low. Although the introduction of a protecting
group for this amino function will add additional steps to the syn-
thesis sequence, it will also result in more lipophilic intermediates,
which could easily be purified by flash chromatography.
11: R = S(O)2NH2
vi
H2N
NH2
CbzHN
O
NHCbz
N
O
N
N
R N
O
O
R N
HN
HN
O
O
N
S
N
O
S
N
O
O
O
vii
OH OH
O
O
Ph
13a : R = (CH3)2CH
12a : R = (CH3)2CH
13b : R = H2N(CH2)4
13c : R = H2N(CH2)2
12b : R = CbzNH(CH2)4
12c : R = CbzNH(CH2)2
12d : R = CbzNH(CH2)3
12e : R = BnO(CH2)2
13d : R = H2N(CH2)3
13e : R = HO(CH2)2
13f : R = (HO)2P(O)OCH2
13g : R = 4-HO(C6H4)CH2
13h : R = (1H-indol-3-yl)CH2
12f : R = (BnO)2P(O)OCH2
12g : R = 4-BnO(C6H4)CH2
12h : R = (1H-indol-3-yl)CH2
Scheme 2. Synthesis of sulfamoylated aa-AMP analogues. Reagents and conditions: (i)
ZnCl2 (5 equiv), benzaldehyde, rt, 72 h, 92%; (ii) TBDMS-Cl (3 equiv), imidazole
(7 equiv), pyridine, rt, 24 h, 94%; (iii) Rapoport’s reagent (3.4 equiv), DCM, rt, 24 h, 96%;
(iv) TBAF (4 equiv), THF, rt, 24 h, 95%; (v) sulfamoyl chloride (2.2 equiv), DMAP
(2.3 equiv), DCM, 0 ꢀC/rt, 24 h, 96%; (vi) amino acid (3 equiv), PS-DCC (4 equiv),
DMAP (3 equiv), DCM/DMF, rt, 24 h, 49e85%; (vii) continuous-flow hydrogenation,
water/2-propanol (5:95 v/v), flow rate¼1 mL/min, 50 bar, 70 ꢀC, 10% Pd/C CatCart,
30ꢁ4 mm, 120 min, 20e78%.
Considering these aspects we designed a general and conver-
gent protecting group strategy for the synthesis of sulfamoylated
aa-AMPs. We reasoned that the combination of a benzyl carbamate
(Cbz) group for protection of the exocyclic amino function of the
adenine moiety as well as the amino function of the amino acids,

I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
1509
Adenosine was first treated with benzaldehyde in the presence
of zinc chloride (5 equiv) to protect the 20-and the 30-hydroxyl
groups yielding 7 in 92% after column chromatography. Subsequent
50-O-tert-butyldimethylsilyl (TBDMS) protection using TBDMSeCl
and imidazole in pyridine furnished compound 8 in 94% yield after
purification by flash chromatography. The exocyclic amino group
was protected as a benzyl carbamate using Rapoport’s reagent (1-
benzyloxycarbonyl-3-ethylimidazolium tetrafluoroborate).28 A so-
lution of 8 in DCM was added dropwise to the freshly prepared
acylimidazolium salt in DCM and the mixture was stirred over-
night. Compound 9 was obtained in 96% yield after purification by
flash chromatography. Subsequent removal of the 50-O-silyl pro-
tective group using tetrabutylammonium fluoride (TBAF) pro-
ceeded smoothly yielding 10 in 95% yield after flash
chromatography.
straightforward. We therefore decided to test a range of different
coupling reagents, including those that can be used for in situ
generation of the required active ester (Table 2).
Table 2
Different coupling mixtures used for amide bond formationa
Entry
Coupling mixture
Conversionc
1
2
3
4
5
6
7
8
9
10
aa-OSu/DBU
aa-Pfp/HOBt
aa-OH/TBTU/HOBt
aa-OH/PyBrOP
aa-OH/HATU/DIPEA
aa-OH/EDC/HOBt
aa-OH/DCC/DMAP
aa-OH/PS-IIDQb
aa-OH/PS-EDC/HOBtb
aa-OH/PS-DCC/DMAPb
Moderate
Low
Low
2.3. Sulfamoylation
Low
Moderate
Moderate
High
Moderate
Moderate
High
Several protocols for sulfamoylation of 20,30-O-isopropylidene
protected adenosine have been reported in the literature including
sulfamoyl chloride and NaH in DMF,29 sulfamoyl chloride and
DBU,30 or sulfamoyl chloride in DMA.31 We decided to test various
bases differing in strength and in steric hindrance (Table 1). Strong
bases such as NaH (entry 1) and DBU (entry 2) gave only low yields
of 11, partly due to decomposition of sulfamoyl chloride.
a
Reaction conditions: 11 (0.15 mmol), amino acid (1 equiv), DMF, overnight, rt,
inert atmosphere.
b
Coupling agent polymer bound to polystyrene.
Determined by LCMS, low¼10e40%, moderate¼40e65%, high¼65e99%.
c
Table 1
Different bases used for sulfamoylation of 10a
N-Hydroxysuccinimide activated valine in combination with
DBU (entry 1) gave moderate conversion of 11 to 12a, while the
pentafluorophenyl activated valine gave hardly any product for-
mation at all (entry 2). Other commonly used coupling reagents like
TBTU/HOBt, PyBrOP and HATU (entries 3e5) gave only low to
moderate conversion of the starting material to the product.
However, the reaction with HATU stopped after only 1 h, probably
due to the poor stability of the coupling reagent. The carbodiimide-
based coupling reagents EDC (entry 6) and DCC (entry 7) gave
moderate to high conversation. Although DCC resulted in high
conversion of the starting material, the byproduct N,N0-dicyclo-
hexylurea is often difficult to remove from the reaction mixture. We
therefore decided to test polymer bound DCC for the conversion of
11 to 12a. We also included polymer bound EDC as well as polymer
bound IIDQ in the tests. The polymer bound coupling reagents were
first preincubated with the Cbz-protected valine for 1 h before the
resin was washed and suspended in dry DMF and mixed with
a solution of 11. Polymer bound DCC gave excellent conversion
(entry 10), while the use of PS-EDC (entry 9) or PS-IIDQ (entry 8)
resulted in only moderate conversion.
Entry
Base
Yield (%)
1
2
3
4
5
6
NaH
DBU
TEA
DIPEA
DMAb
DMAPc
13
17
d
d
41
96
a
Reaction conditions: 10 (0.15 mmol), sulfamoyl chloride (1 equiv), DCM, 4 h, rt,
inert atmosphere.
b
DMA as solvent, 4 h, rt, inert atmosphere.
Sulfamoyl chloride (2.2 equiv), DMAP (2.3 equiv), 0 ꢀC. 4 h, inert atmosphere.
c
The use of weaker but more sterically hindered amine bases,
such as TEA (entry 3) or DIPEA (entry 4), resulted in only trace
amounts of the target product. The use of DMA as solvent without
the addition of any base has been reported to give sulfamoylation of
alcohols in high yields.31 Unfortunately, in our hands this method
only resulted in a moderate yield of product (entry 5). Another
known method comprised the reaction of N-(tert-butoxycarbonyl)
sulfamoyl chloride with DMAP to form a non-moisture sensitive
and stable azanide salt that allows sulfamoylation of amines under
very mild conditions.32 We therefore tested DMAP as a base (entry
6) in the sulfamoylation reaction and obtained 11 in an excellent
yield of 96% after purification by flash chromatography.
Compounds 12aeh were synthesised using PS-DCC/DMAP and
could be obtained in 49e85% yield after column chromatography
and preparative HPLC. In the 1H and 13C NMR spectra doubled
signals were observed. From variable temperature 1H and 13C
NMR experiments it could be concluded that 12aeh adopts two
different conformations with a high activation energy for the
interconversion.33
2.5. Deprotection by catalytic hydrogenation
We decided to use catalytic hydrogenation for deprotection of
12aeh using a continuous flow, high pressure device (H-cubeÒ)
that allowed easy testing of different types of catalysts and varia-
tions of reactions conditions such as hydrogen pressure, solvents
and temperature (Table 3).
The initial tests were carried out using 5% Pd/C, MeOH as solvent
at 1 bar, rt and a reaction time of 40 min (entry 1). LCMS analysis of
the reaction mixture showed 10e20% conversion of 12a to the
2.4. Amino acid coupling reaction
A common method for coupling protected amino acids to sul-
famoyl moieties is to use N-(tert-butyl carbamate) (Boc) protected
N-hydroxysuccinimide activated amino acids in the presence of
DBU.24,26 However, not all amino acids are commercially available
as hydroxysuccinimide esters and their preparation is not always

1510
I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
Table 3
N-alkylation to give 14d, but did not suppress the formation com-
pletely. However, running the reaction at 50 bar and 70 ꢀC for
120 min resulted in full conversion of 12a to 13a with only trace
amounts of 14a, 14d, 15 and 16. Using t-BuOH as solvent (entry 9) or
Pd(OH)2 as catalyst (entry 10) resulted in much slower conversion
of the starting material and an incomplete reaction.
Different reaction conditions used for hydrogenolytic deprotection of 12a
(0.015 mmol)
R
NH
NH2
N
N
HN
NH2
O
Ad
Based on these results we decided to carry out the deprotection
of 12aeh using 2-propanol as solvent, 70 ꢀC, 50 bar and a reaction
time of 120 min. Hydrogenolytic deprotection of 12a gave 13a in
58% yield, with trace amounts of the byproducts 14d, 15, 16 and
adenosine were also detected. While deprotection of 12b resulted
in 36% of 13b, byproduct 15 was also formed in approximately 35%
yield, in addition to trace amounts of adenosine and 15. The low
yield of 13b was probably due to the amino acid side chain having
a favourable length (n¼3) to allow the undesired lactam formation
described in Fig. 2. We reasoned that the relatively high pressure
and temperature applied during the hydrogenation could favour
byproduct 16 and adenosine formation (Table 3). Hydrogenation of
12c formed the desired product 13c in 78% yield with only traces of
byproduct. The deprotection of 12d resulted mainly in the forma-
tion of byproduct 15 (approximately 60%) while 13d was only iso-
lated in 20% yield. The low yield of 13d (where n¼2) was probably
due to lactam formation as described for deprotection of 12b.
Hydrogenolysis of 12e also resulted in the byproduct 15 as the
major product with 13e (where n¼2) isolated in 40% yield due to
lactone formation. Deprotection of 12f, 12g and 12h resulted in
isolation of 13f in 77%, 13g in 66% and 13h in 60% yield. Traces of
byproduct 16 could be observed and the considerably better yields
were probably due to the amino acid side chains in 12f, 12g and 12h
not able to perform the undesired intramolecular cyclisation re-
action (Fig. 2). The synthesis of compounds 13g and 13h has been
published earlier. Even though our synthetic strategy requires more
steps then methods reported in the literature to attain the target
compounds, the overall yields are comparable for 13h35 and even
higher for 13g.11
+
O S O
O S O
N
Ad
N
O
O
O
O
O
+
+
+
a
a
13
12
H H
O O
O
O
O
O
Ph
16
Ph
a,
14
15
R H
=
,
14b
R
R
R
H
=C
H3
H
c,
14
=C 2C
,
14d
H
(
H3
=C
C
)
3 2
Entry
Catalyst
5% Pd/C
10% Pd/C
10% Pd/C
10% Pd/C
10% Pd/C
10% Pd/C
10% Pd/C
10% Pd/C
10% Pd/C
Solvent
Pressure
(bar)
Temp
(ꢀC)
Time
Conversionb
(min)
12a/13a
1
2
3
4
5
6
7
8
9
10
MeOH
EtOH
EtOH
1
1
1
rt
rt
rt
rt
30
50
50
70
70
70
40
40
80
40
40
80
80
120
120
120
Low
Low
Low
Low
Moderate
Moderate
Moderate
High
Low
Moderate
EtOH
10
30
50
50
50
50
50
EtOHa
EtOHa
2-PrOHa
2-PrOHa
tBuOHa
2-PrOHa
20% Pd(OH)2
a
With 5% water present.
Determined by LCMS, low¼10e40%, moderate¼40e65%, high¼65e99%.
b
desired product 13a. Unfortunately, the major product formed in
the reaction was intermediate 14a (50%). Traces of product (<5%)
with a mass indicating deprotection of one of the two Cbz groups
were also detected. Prolonged reaction time, higher pressure or
temperature did not improve the yield of 13a significantly (data not
shown).
3. Conclusions
In order to accelerate the reaction and to increase the solu-
bility of 12a, 10% Pd/C was tested in combination with EtOH as
solvent (entry 2). LCMS analysis of the reaction mixture after
40 min showed a conversion of approximately 65% of starting
material to 14a. In addition, the same byproduct as identified in
entry 1 (one Cbz group removed) was obtained in comparable
amount. The desired product 13a was detected in 25e35% yield
by LCMS.
We have developed a convenient and convergent protecting
group strategy for the synthesis of sulfamoylated aa-AMP ana-
logues. The selected protecting groups can be incorporated in high
yields, they withstand the applied reaction conditions, and they
can be removed by hydrogenolysis in a single step under neutral
conditions to avoid product decomposition. The developed syn-
thetic protocol should be useful for the preparation of a range of
natural and non-proteinogenic amino acid sulfamoyl adenolates.
Careful monitoring and optimization of the reaction conditions
allow the formation of most of these byproducts to be kept at
a minimum. The synthesis protocol leading to the target com-
pounds requires more steps than published methods (introduction
and removal of the protecting groups) but one of the advantages is
a simplified purification (due to increased lipophilicity). The
overall isolated yields are comparable and even higher than those
in reported methods.11,35 Our method makes it possible to prepare
a range of new and novel sulfamoyloxy-linked aminoacyl-AMP
analogues.
Different pressures, temperatures and reaction times (entries
3e6) were investigated to improve the conversion of 12a to the
target compound 13a. However, increasing temperature and pres-
sure also leads to formation of an additional byproduct 14c. The
formation of the latter product can be explained by de-
hydrogenation of ethanol to acetaldehyde by the palladium catalyst
and subsequent reaction of the amino group of the valinyl moiety
with the aldehyde to form a Schiff base, which was reduced to af-
ford an N-ethylated amine.34 The corresponding byproduct 14b was
observed when the hydrogenation was performed in MeOH at high
pressure and high temperature (data not shown). To reduce the
amount of N-alkylation, ethanol containing 5% water was used as
solvent (entry 5) and the reaction time was extended to 80 min to
increase the conversion of the starting material. Although more
than 80% of the starting material had been consumed, compound
14a was the major product and only trace amounts of 13a were
detected. Furthermore, the water did not supress the N-alkylation
of the valinyl moiety to give 14c. However, at 50 bar, 50 ꢀC and
a reaction time of 80 min additional byproducts (15 and 16, <20%)
were detected, in addition to 14c. Running the hydrogenation
reaction in 2-propanol (entries 7 and 8) reduced the amount of
4. Experimental section
4.1. General
All commercial chemicals were used without prior purification.
Dichloromethane and pyridine were distilled from calcium hydride.
Tetrahydrofuran was distilled from sodium/benzophenone. All re-
actions were monitored by TLC (Merck silica gel 60 F254) and ana-
lysed under UV (254 nm). Column chromatography was performed

I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
1511
by manual flash chromatography (wet packed silica,
4.4. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-(tert-
0.04e0.063 mm) or by automated column chromatography on
a Biotage SP-4 instrument using pre-packed silica columns. Pre-
parative high performance liquid chromatography (HPLC) was
carried out on a Waters 600 controller connected to a Waters 2487
butyldimethylsilyl)adenosine (9)
A solution of 8 (5.5 g, 11.7 mmol) in dry DCM (50 mL) was
added dropwise to a stirred solution of freshly prepared Rapo-
port’s reagent (1-(benzyloxycarbonyl)-3-ethylimidazolium tetra-
fluoroborate) in DCM (100 mL, 0.4 M) at rt under N2 atmosphere.
After 24 h, the reaction mixture was quenched by addition of
a saturated aqueous solution of NaHCO3 (50 mL) and diluted with
DCM (50 mL). The organic layer was separated, washed with water
(20 mL), dried over MgSO4, filtered and the solvent was removed
under reduced pressure. The crude product was purified by flash
chromatography (stepwise gradient from 2 to 20% v/v MeOH in
DCM), yielding compound 9 as a white foam (6.8 g, 96%). Rf¼0.7
Dual
l mm C-18
Absorbance detector using a AtlantisÒ Prep T3 5
(250ꢁ19 mm) column unless otherwise stated. Microwave re-
actions were performed in a Biotage Initiator reactor with fixed
hold time. 1H (400 MHz) and 13C (100 MHz) NMR spectra were
obtained from a JEOL JNM-EX 400 spectrometer. IR spectra were
acquired on a ChiralIR-2X Biotools instrument. Measurements of
the optical rotations were performed on a Perkin Elmer 341LC
polarimeter. Melting point determined on a Mettler FP800 appa-
ratus without corrections.
(MeOH/DCM, 1:10, v/v). 1H NMR (CDCl3)
d 0.05 (6H, s), 0.81 (9H, s),
3.74e3.82 (2H, m), 4.61 (1H, br s), 5.06 (1H dd, J 6.2 and 1.5 Hz),
5.23 (2H, br s), 5.49 (1H, dd, J 6.2 and 1.8 Hz), 6.02 (1H, s), 6.23 (1H,
d, J 2.20 Hz), 7.31e7.61 (10H, m), 8.14 (1H, s), 8.79 (1H, s), 9.61 (1H,
4.2. 20,30-O-Benzylideneadenosine (7)
Adenosine (5.0 g, 18.8 mmol) and dry ZnCl2 (10.5 g, 93.6 mmol)
was suspended in 30 mL freshly distilled benzaldehyde (100 ꢀC,
12 mbar). The reaction mixture was stirred at rt for 72 h under N2
atmosphere. The solvent was removed under reduced pressure
and the mixture was co-distilled with toluene. The yellow glue-
like residue was suspended in ethyl acetate (100 mL) and
washed with saturated NaHCO3 solution (30 mL). The aqueous
layer was extracted with ethyl acetate (3ꢁ250 mL). The combined
organic layers were washed with water (200 mL), dried over
MgSO4, filtered and the solvent removed under reduced pressure
and the residue was co-distilled with toluene. The crude product
was dissolved in DCM/MeOH, silica gel (10 g) was added and the
volatiles were removed under reduced pressure. The adsorbed
residue was purified by column chromatography (stepwise gra-
dient from 0e10% v/v MeOH in CHCl3), yielding 7 (6.1 g, 92%) as
white crystals, mp 201e203 ꢀC (lit. mp 204 ꢀC36). Rf¼0.3 (MeOH/
DCM, 1:10, v/v). NMR data were in agreement with published
data.37
s). 13C NMR (CDCl3)
d 5.6, 18.2, 25.8, 63.4, 67.7, 69.7, 76.9, 77.5, 82.9,
85.2, 87.3, 91.7, 107.5, 122.1, 126.9, 128.3, 128.4, 128.5, 128.6, 128.7,
130.0, 135.9, 136.0, 141.8, 149.7, 151.2, 152.9. Anal. Calcd for
C31H37N5O6Si$H2O: 59.88 (C); 6.32 (H); 11.26 (N). Found: 59.81 (C);
6.09 (H); 11.01 (N).
4.5. 6-N-Benzyloxycarbonyl-20,30-O-benzylideneadenosine (10)
TBAF (1 M in THF, 10 mL) was added to a solution of 9 (1.5 g, 2.5)
in dry THF (10 mL), the reaction mixture was stirred overnight at rt
under N2 atmosphere. TLC (MeOH/DCM, 1:10, v/v), showed traces
of starting material and additional TBAF solution (1 M in THF, 3 mL)
was added and the reaction mixture was stirred for additional 5 h at
rt under N2 atmosphere. The reaction was quenched by the addition
of Dowex x 50w (20 mL mix of resin in pyridine) and the reaction
mixture stirred gently for 20 min. The Dowex was filtered off by
suction, washed with a pyridine/methanol/water solution (3:1:1,
3ꢁ20 mL) and the solvents were removed under reduced pressure
and co-distilled with toluene. The crude product was purified by
automated flash chromatography (stepwise gradient, 2e20% v/v,
MeOH in DCM), yielding compound 10 as a white foam (2.1 g, 95%).
4.3. 20,30-O-Benzylidene-50-O-(tert-butyldimethylsilyl)
adenosine (8)
Rf¼0.5 (MeOH/DCM, 1:10, v/v). 1H NMR (CDCl3)
d 3.80e3.92 (2H,
m), 4.63 (1H, s), 5.13e5.24 (4H, m), 5.92 (1H, d, J 4.4 Hz), 6.00 (1H,
Compound 7 (3.3 g, 7.6 mmol), imidazole (4.6 g, 67.6 mmol) and
TBDMSeCl (5.0 g, 33.4 mmol) were stirred in dry pyridine (30 mL)
for 24 h at rt under N2 atmosphere. The reaction was quenched by
the addition of ice-water (100 mL). The aqueous solution was
extracted with CHCl3 (3ꢁ100 mL), the organic phases were com-
bined and the solvent was removed under reduced pressure and
co-distilled with toluene. Aqueous acetic acid (40 mL, 80%) was
added to the residue and the mixture was stirred for 20 min at rt.
The reaction was quenched by the addition of ice-water (100 mL)
and the aqueous solution extracted with CHCl3 (3ꢁ100 mL). The
organic layers were pooled and solid NaHCO3 (approximately 10 g)
was added, the suspension was stirred for 45 min and washed with
water (2ꢁ100 mL), the organic layer was separated, dried over
MgSO4, and filtered before the solvent was removed under reduced
pressure and the residue was co-distilled with toluene. The crude
product was purified by automated flash chromatography (step-
wise gradient, 2e20% v/v, MeOH in DCM), yielding 8 as a white
foam (4.1 g, 94% yield). Rf¼0.4 (MeOH/DCM, 1:10, v/v). 1H NMR
s), 7.24e7.42 (10H, m), 7.95 (1H, s), 8.68 (1H, s), 9.63 (1H, s). 13C
NMR (CDCl3)
d 62.9, 67.7, 83.3, 83.4, 86.0, 93.1, 107.5, 123.0, 126.5,
128.5, 128.6, 128.6, 129.9, 135.2, 135.7, 142.7, 150.0, 150.2, 151.1,
152.4. Anal. Calcd for C25H23N5O6$½H2O: 60.27 (C); 5.06 (H); 14.05
(N). Found: 60.39 (C); 4.98 (H); 14.11 (N).
4.6. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-
sulfamoyladenosine (11)
Compound 10 (1.7 g, 3.50 mmol) was dissolved in dry DCM
(10 mL) at 0 ꢀC. DMAP (1.0 g, 8.2 mmol) was added and the re-
action mixture was stirred for 20 min. Sulfamoyl chloride (0.9 g,
7.8 mmol) suspended in dry DCM (2 mL) was added dropwise to
the reaction mixture at 0 ꢀC, the pH was carefully monitored
during the addition and was kept at pH 7 by adding small portions
of DMAP when pH<7. The mixture was stirred overnight at rt
under N2 atmosphere. The reaction was quenched by the addition
of H2O (50 mL). EtOAc (100 mL) was added, the layers were sep-
arated and the aqueous phase was extracted with EtOAc
(3ꢁ100 mL). The pooled organic layers were washed with H2O
(100 mL) and brine (100 mL), dried over MgSO4 and filtered before
the solvent was removed under reduced pressure. The crude
product was purified using automated flash chromatography
(stepwise gradient, 2e20% v/v, MeOH in DCM), yielding compound
11 as a white foam (1.9 g, 96%). Rf¼0.4 (MeOH/DCM, 1:10, v/v). 1H
(CDCl3)
d 0.01 (6H, s), 0.08 (9H, s), 3.75e3.90 (2H, m), 4.59e4.61
(1H, m), 5.09 (1H, dd, J 6.2 and 2.2 Hz), 5.52 (1H, dd, J 6.6 and
2.6 Hz), 5.75 (2H, br s), 6.04 (1H, s), 6.30 (1H, d, J 2.6 Hz), 7.43e7.44
(3H, m), 7.55e7.60 (2H, m), 8.05 (1H, s), 8.37 (1H, s). 13C NMR
(CDCl3)
d 5.4, 18.4, 25.9, 63.6, 83.0, 85.4, 87.4, 91.4, 107.6, 120.1,
126.8, 127.0, 128.6, 128.6, 130.1, 135.9, 139.5, 149.4, 153.1, 155.9. Anal.
Calcd for C23H31N5O4Si: 58.83 (C); 6.65 (H); 14.91 (N). Found: 58.81
(C); 6.71 (H); 14.83 (N).

1512
I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
NMR (CDCl3)
d
4.20e4.38 (2H, m), 4.64 (1H, q, J 6.2 and 2.2 Hz),
(CD3CN) d 1.61e1.74 (2H, m), 1.90e1.98 (2H, m), 3.02e3.17 (4H, m),
5.07e5.12 (3H, m), 5.42 (1H, dd, J 6.6 and 1.8 Hz), 5.91 (1H, s), 6.18
(3H, br s), 7.21e7.50 (10H, m), 8.05 (1H, s), 8.62 (1H, s), 9.44 (1H,
3.93e4.03 (2H, m), 4.15e4.21 (4H, m), 4.54e4.59 (1H, m),
4.64e4.69 (1H, m), 4.90e5.20 (14H, m), 5.31 (2H, s), 5.89 (1H, s),
6.13 (1H, s), 6.30e6.36 (2H, m), 7.17e7.54 (44H, m), 8.55 (1H, s),
s). 13C NMR (CDCl3)
d 68.0, 69.3, 82.3, 84.6, 84.8, 90.7, 107.9, 122.2,
126.9, 128.6, 128.8, 130.3, 135.4, 142.6, 149.5, 150.8, 151.6, 152.8.
Anal. Calcd for C25H24N6O8S$H2O: 51.19 (C); 4.47 (H); 14.33 (N).
Found: 51.08 (C); 4.29 (H); 14.11 (N).
8.57 (1H, s), 8.58 (1H, s), 8.62 (1H, s). 13C NMR (CD3CN)
d 25.5, 31.5,
34.3, 36.8, 38.5, 38.5, 43.6, 54.2, 56.2, 66.9, 67.1, 67.1, 67.2, 67.4, 68.2,
68.7, 69.1, 69.2, 82.3, 84.1, 84.9, 85.4, 86.1, 86.3, 90.9, 91.9, 104.9,
108.1, 123.3, 127.9, 128.0, 128.5, 128.7, 128.8, 128.8, 128.9, 128.9,
129.0, 129.1, 129.2, 129.3, 129.3, 123.4, 129.5, 129.5, 129.5, 129.6,
129.6, 129.7, 130.8, 131.0, 136.80, 137.0, 137.1, 137.2, 138.0, 138.1,
138.3, 143.9, 150.3, 150.3, 152.3, 152.4, 153.0, 153.2, 153.2, 157.5,
157.6, 163.7, 173.2, 179.5. HRMS m/z [MþH]þ calculated for
C45H44N8O13S: 937.2821. Found: 937.2828.
4.7. General procedure for the synthesis of 6-N-
benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(aminoacyl)-
sulfamoyl]adenosines (12aeh)
The protected amino acid (3 equiv) was dissolved in dry DCM
and dry DMF if necessary (6 mL). PL-DCC (1.5 mmol loading,
4 equiv) was added, the microvial was capped and stirred gently at
rt under N2 atmosphere for 1 h. Compound 11 (1 equiv) and DMAP
(3 equiv) were dissolved in dry DCM (1 mL) and added to the re-
action mixture, which was stirred gently at rt under N2 atmosphere
for 24 h. The resin was filtered off and washed with dry DCM
(3ꢁ10 mL) and MeOH (3ꢁ10 mL). The solvents were removed un-
der reduced pressure. The crude products were purified using au-
tomated flash chromatography (stepwise gradient, 2e20% v/v,
MeOH in DCM) followed by preparative HPLC (gradient from 27.5%
MeCN in 50 mM phosphate buffer to 45% ACN and 45% MeOH in
50 mM, phosphate buffer, pH 7.0 and a flow of 15 mL/min).
4.7.4. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz-
L
-ornithinyl(
eral procedure compound 11 (0.20 g, 0.35 mmol) was reacted with
N-Cbz- -ornithine( -Cbz) (0.42 g, 1.06 mmol) yielding 12d (0.19 g,
73%) as white foam. 1H NMR (CD3CN)
1.42e2.22 (8H, m),
d-Cbz))-sulfamoyl]adenosine (12d). Following the gen-
L
d
d
2.89e2.99 (4H, m), 3.86e3.98 (2H, m), 4.08e4.16 (4H, m),
4.62e4.73 (2H, m), 4.91e5.14 (14H, m), 5.24e5.31 (2H, m), 5.80 (2H,
br s), 5.89 (1H, s), 6.03 (1H, s), 6.30 (2H, s), 7.20e7.54 (40H, m), 8.55
(2H, s), 8.67 (2H, s), 9.45 (1H, br s). 13C NMR (CD3CN)
d 26.8, 31.1,
41.2, 58.0, 66.8, 67.0, 68.3, 69.1, 82.2, 84.9, 85.4, 86.1, 86.3, 90.8, 90.8,
91.8, 104.9, 104.9 108.1, 123.3, 127.9, 128.0, 128.7, 128.8, 128.8, 129.1
129.2, 129.4, 129.4, 123.5, 129.5, 130.8, 131.0, 137.0, 137.1, 138.2,
138.4,144.0,150.3,150.3,152.3, 152.3,153.1,153.2,157.4,157.6,157.7,
180.0. HRMS m/z [MþH]þ calculated for C46H48N8O13S: 951.2978.
Found: 951.2972.
4.7.1. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz-
valinyl)sulfamoyl]adenosine (12a). Following the general procedure
compound 11 (0.20 g, 0.35 mmol) was reacted with N-Cbz- -valine
L-
L
(0.27 g, 1.06 mmol) yielding 12a (0.24 g, 85%) as a beige foam.
Rf¼0.4 (MeOH/DCM, 1:10, v/v). 1H NMR (CD3CN)
d
0.76 (6H, d, J
4.7.5. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz)-
6.82 Hz), 0.86 (6H, d, J 6.75 Hz), 1.98e2.12 (2H, m), 3.80e3.90 (2H,
m), 4.18e4.24 (4H, m), 4.60 (1H, q, J 3.82 and 7.83 Hz), 4.68e4.72
(1H, m), 4.92e5.12 (5H, m), 5.15e5.25 (5H, m), 5.36 (1H, s), 5.38
(1H, s), 5.94 (1H, s), 6.16 (1H, s), 6.35 (1H, d, J 2.29 Hz), 6.37 (1H, d, J
2.29 Hz), 7.21e7.56 (35H, m), 8.53 (1H, s), 8.58 (2H, s), 8.60 (1H, s).
L
-homoserinyl(Bn)sulfamoyl]adenosine (12e). Following the general
procedure compound 11 (0.2 g, 0.35 mmol) was reacted with N-
Cbz- -homoserine(OBn) (0.36 g, 1.06 mmol) yielding 12e (0.16 g,
51%) as white foam. 1H NMR (CD3CN)
1.71e1.86 (2H, m),1.94e2.08
L
d
(2H, m), 3.37e3.49 (4H, m), 4.06e4.20 (4H, m), 4.23e4.39 (2H, m),
4.54e4.61 (1H, m), 4.64e4.71 (1H, m), 4.88e5.19 (10H, m),
5.22e5.32 (2H, m), 5.90 (1H, s), 6.14 (1H, s), 6.37 (2H, s), 7.18e7.54
13C NMR (CD3CN)
d 18.1, 20.3, 32.5, 63.6, 63.7, 67.1, 68.3, 69.2, 82.4,
84.2, 84.9, 85.4, 86.1, 86.4, 91.0, 91.9, 105.1, 108.3, 123.4, 128.0, 128.1,
128.7,128.7,128.9, 129.3, 129.4, 129.5, 129.6, 129.7,131.0,131.1, 137.2,
137.3, 137.3, 138.4, 144.0, 150.5, 150.5, 152.4, 152.5, 153.1, 153.3,
157.9, 179.7. HRMS m/z [MþH]þ calculated for C38H39N7O11S:
802.2501. Found: 802.2500.
(44H, m), 8.50e8.58 (3H,m), 8.66 (1H, s). 13C NMR (CD3CN)
d 31.4,
33.6, 36.7, 56.2, 56.3, 68.1, 68.2, 73.4, 82.2, 84.0, 84.9, 85.4, 86.1, 86.4,
90.8, 91.8, 104.9, 108.0, 123.3, 127.7, 127.9, 128.0, 128.3, 128.6, 128.7,
129.0,129.1,129.2,129.4,129.5,129.5,129.8,130.8,131.0,137.1,137.2,
138.2, 139.8, 144.0, 150.3, 152.4, 152.5, 153.0, 153.1, 157.4, 163.6,
180.0. HRMS m/z [MþH]þ calculated for C44H43N7O12S: 894.2763.
Found: 894.2750.
4.7.2. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz-
L
-lysinyl(
3 -Cbz))sulfamoyl]adenosine (12b). Following the general
procedure compound 11 (0.20 g, 0.35 mmol) was reacted with N-
Cbz-
L
-lysine(
3
4.7.6. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz)-
a white foam. Rf¼0.4 (MeOH/DCM, 1:10, v/v). 1H NMR (CD3CN)
L
-serinyl(P(O)(OBn)2)sulfamoyl]adenosine
general procedure compound 11 (0.20 g, 0.35 mmol) was reacted
with N-Cbz- -serine phosphate(OBn)2 (0.05 g, 0.11 mmol) yield-
ing 12f (0.02 g, 61%) as white foam. 1H NMR (CD3CN)
4.12e4.18
(12f). Following
the
d
1.29e1.44 (8H, m), 1.50e1.61 (2H, m), 1.68e1.79 (2H, m),
2.96e3.08 (4H, m), 3.85e3.91 (2H, m), 4.12e4.20 (4H, m),
4.62e4.68 (1H, m), 4.71e4.77 (1H, m), 4.98e5.08 (7H, m), 5.11e5.13
(1H, m), 5.17e5.25 (5H, m), 5.34e5.42 (3H, m), 5.72 (1H, br s),
5.93e5.98 (3H, m), 6.20 (1H, s), 6.37 (1H, d, J 2.29 Hz), 6.38e6.40
(2H, m), 7.24e7.61 (40H, m), 8.59 (1H, s), 8.61 (1H, s), 8.63 (1H, s),
L
d
(4H, m), 4.26e4.67 (8H, m), 4.92e5.02 (12H, m), 5.10e5.17 (2H,
m), 5.26e5.30 (2H, m), 5.86 (1H, s), 6.13 (1H, s), 6.24e6.30 (3H,
m), 7.21e7.55 (52H, m), 8.57 (1H, s), 8.58 (1H, s), 8.61 (1H, s), 8.61
8.70 (1H, s). 13C NMR (DMSO-d6)
d
22.9, 29.0, 57.0, 65.1, 65.1, 66.3,
(1H, s). 13C NMR (CD3CN)
d 58.2, 58.2, 67.1, 68.1, 69.0, 69.3, 69.4,
37.1, 80.8, 83.3, 83.8, 88.1, 89.6, 103.1,106.5,123.3,126.9,127.0,127.5,
127.6, 127.7, 127.9, 128.0, 128.3, 128.4, 128.4, 128.5, 129.7, 129.9,
134.0, 136.1, 136.3, 137.2, 137.3, 149.7,151.5, 152.0, 155.8,155.9, 155.9,
156.1, 176.9. HRMS m/z [MþH]þ calculated for C47H48N8O13S:
965.3134. Found: 965.3133.
70.2, 70.2, 70.4, 81.5, 82.3, 84.1, 85.1, 85.6, 86.1, 86.4, 91.1, 92.1,
104.9, 108.0, 123.4, 127.9, 128.0, 128.7, 128.8, 129.0, 129.1, 129.2,
129.3, 129.4, 129.5, 129.5, 129.7, 130.8, 131.0, 137.0, 137.1, 137.2,
137.5, 138.1, 143.8, 145.4, 150.3, 150.4, 152.4, 152.45, 152.5, 152.9,
153.0, 153.1, 156.6, 157.1, 157.1, 174.1, 175.3, 175.4. HRMS m/z
[MþHþK]þ calculated for C50H48N7O15PS: 1088.2298. Found:
1088.2229.
4.7.3. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(2,4-
di(benzyloxycarbonylamino)-
Following the general procedure compound 11 (0.20 g, 0.35 mmol)
was reacted with N,N0-Cbz-
-2,4-diaminobutanoic acid (0.41 g,
1.06 mmol) yielding 12c (0.16 g, 49%) as white foam. 1H NMR
L
-butyryl)sulfamoyl]adenosine (12c).
4.7.7. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz-
L
L
-tyrosyl(OBn))sulfamoyl]adenosine (12g). Following the general
procedure compound 11 (0.20 g, 0.35 mmol) was reacted with N-

I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
1513
Cbz-
L
-tyrosine(OBn) (0.43 g, 1.06 mmol) yielding 12g (0.20 g, 60%)
3.01e3.06 (2H, m), 4.12e4.18
(1H, t, J 6.2 Hz), 4.47e4.21 (3H, m), 4.52 (1H, t, J 4.5 Hz), 4.72 (1H, t,
J 5.3 Hz), 6.17 (1H, d, J 5.3 Hz), 8.31 (1H, s), 8.38 (1H, s). dC
(100 MHz; D2O) 22.31, 28.71, 33.42, 42.09, 53.21, 63.11, 70.84,
72.87, 81.89, 97.01, 119.40, 140.21, 149.87, 151.98, 155.93, 175.85.
HRMS m/z [MþH]þ calculated for C16H26N8O7S: 475.1723. Found:
475.1724.
as white foam. 1H NMR (CD3CN)
d
(8H, m), 4.57e4.63 (1H, m), 4.68e4.75 (1H, m), 4.87e5.45 (18H,
m), 6.17 (1H, s), 6.33 (1H, s), 6.34e6.50 (2H, m), 6.76e7.07 (8H, m),
7.21e7.57 (44H, m), 8.55 (2H, s), 8.61 (2H, s). 13C NMR (CD3CN)
d
37.4, 38.5, 56.7, 59.6, 67.8, 67.1, 67.7, 68.2, 69.0, 69.1, 70.5, 70.6,
82.2, 84.0, 84.9, 85.3, 86.0, 86.3, 90.9, 91.9, 104.9, 108.0, 115.3,
115.7, 123.4, 127.9, 128.0, 128.5, 128.6, 128.7, 128.8, 128.9, 128.9,
129.1, 129.2, 129.2, 129.3, 129.4, 129.5, 130.0, 130.8, 131.0, 131.4,
131.5, 136.9, 137.0, 137.1, 138.1, 138.2, 137.5, 143.8, 150.4, 150.5,
152.3, 152.4, 153.1, 157.0, 157.1, 158.3, 158.7, 172.8, 179.3, 179.3.
HRMS m/z [MþH]þ calculated for C49H45N7O12S: 956.2920. Found:
956.2921.
4.8.3. 50-O-(N-2,4-Diaminobuturyl)sulfamoyladenosine (13c).
Following the general procedure compound 12c (30 mg,
0.03 mmol) was hydrogenated to yield 13c (11 mg, 78%) as a white
foam (HPLC Method One). [
a
]
20 ꢂ0.25 (c 0.83, DMSO). nmax (DMSO)
D
3450, 3270, 3070, 2250, 2130, 1660 cmꢂ1
.
1H NMR (D2O)
d
1.98e2.05 (2H, m), 2.68e2.73 (2H, m), 3.75 (1H, t, J 6.2 Hz),
4.45e4.19 (3H, m), 4.51 (1H, t, J 4.5 Hz), 4.71 (1H, t, J 5.3 Hz), 6.16
(1H, d, J 5.3 Hz), 8.26 (1H, s), 8.35 (1H, s). dC (100 MHz; D2O) 33.25,
37.15, 50.61, 62.89, 69.88, 72.79, 82.19, 96.86, 141.92, 149.29, 152.41,
156.34, 174.24. HRMS m/z [MþH]þ calculated for C14H20N8O7S:
445.1254. Found: 445.1257.
4.7.8. 6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[N-(N-Cbz-
L
-tryptophanyl)sulfamoyl]adenosine (12h). Following the general
procedure compound 11 (0.20 g, 0.35 mmol) was reacted with N-
Cbz- -tryptophan (0.54 g, 1.58 mmol) yielding 12h (0.13 g, 53%)
as white foam. 1H NMR (CD3CN)
2.90e3.08 (2H, m), 3.16e3.21
L
d
(2H, m), 4.10e4.17 (4H, m), 4.30e4.32 (2H, m), 4.51e4.60 (1H,
m), 4.61e4.68 (1H, m), 4.82e5.03 (5H, m), 5.05e5.38 (7H, m),
5.83 (1H, s), 6.12 (1H, s), 6.31 (2H, br s), 6.88e7.53 (44H, m), 8.49
4.8.4. 50-O-(N-Ornithinyl)sulfamoyladenosine (13d). Following the
general procedure compound 12d (30 mg, 0.03) was hydrogenated
20
to yield 13d (3 mg, 21%) as a white foam (HPLC Method One) [a]
D
(1H, s), 8.56e8.66 (3H, m). 13C NMR (CD3CN)
d
29.3, 59.1, 66.9,
ꢂ0.34 (c 0.83, DMSO). nmax (DMSO) 3470, 3430, 2970, 2920, 2870,
2250, 2130, 1660, 1450 cmꢂ1 1H NMR (D2O)
1.46e1.52 (2H, m),
68.3, 69.1, 69.1, 82.3, 84.1, 84.9, 85.4, 86.0, 86.3, 90.9, 91.0, 92.0,
105.1, 108.1, 111.8, 111.9, 112.3, 112.4, 119.6, 119.8, 122.3, 123.3,
124.5, 124.7, 128.0, 128.1, 128.6, 128.8, 129.0, 129.2, 129.4,
129.5, 129.6, 130.9, 131.0, 137.2, 137.2, 137.4, 138.3, 143.9, 150.3,
150.4, 152.4 152.5, 153.0, 153.0, 153.1, 153.2, 157.3, 179.8. HRMS
m/z [MþH]þ calculated for C44H40N8O11S: 889.2610. Found:
889.2618.
.
d
1.77e1.82 (2H, m), 2.70e2.75 (2H, m), 3.61 (1H, t, J 6.2 Hz),
4.48e4.22 (3H, m), 4.54 (1H, t, J 4.5 Hz), 4.70 (1H, t, J 5.3 Hz), 6.15
(1H, d, J 5.3 Hz), 8.31 (1H, s), 8.36 (1H, s). dC (100 MHz; D2O) 24.11,
25.03, 41.34, 53.16, 62.54, 72.32, 82.06, 95.11, 150.10, 152.44, 156.21,
175.02. HRMS m/z [MþH]þ calculated for C15H24N8O7S: 461.1567.
Found: 461.1569.
4.8. General procedure for the synthesis of 50-O-(N-
aminoacyl)sulfamoyladenosines (13aeh)
4.8.5. 50-O-(N-Homoserinyl)sulfamoyladenosine
(13e). Following
the general procedure compound 12e (20 mg, 0.02 mmol) was
hydrogenated to yield 13e (3 mg, 39%) as a white foam (HPLC
6-N-Benzyloxycarbonyl-20,30-O-benzylidene-50-O-[(N-amino-
acyl)sulfamoyl]adenosines (12aeh) (0.03 mmol) were dissolved
in water/2-propanol (5:95 v/v, 6 mL) and hydrogenation was
carried out in an continuous-flow hydrogenation reactor (H-
cubeÒ) (flow rate:1 mL/min; pressure: 50 bar; temperature:
70 ꢀC; catalyst: 10% Pd/C CatCart, 30ꢁ4 mm; time: 120 min). The
solvent was removed under reduced pressure and the com-
pounds were purified using reversed phase preparative HPLC
using Method One (mobile phase; gradient 5e95% MeCN in
Method One). [
a
]
20 ꢂ0.28 (c 0.83, DMSO). nmax (DMSO) 3450, 3270,
D
3070, 2920, 2250, 2130, 2000, 1620 cmꢂ1
.
1H NMR (D2O)
d
1.96e2.01 (2H, m), 3.55e3.63 (2H, m), 3.64 (1H, t, J 6.2 Hz),
4.47e4.21 (3H, m), 4.52 (1H, t, J 4.5 Hz), 4.73 (1H, t, J 5.3 Hz), 6.16
(1H, d, J 5.3 Hz), 8.31 (1H, s), 8.42 (1H, s). dC (100 MHz; D2O) 26.21,
29.93, 53.11, 62.12, 63.90, 82.19, 95.78,119.34,140.13,149.39,152.32,
156.02, 174.60. HRMS m/z [MþH]þ calculated for C14H21N7O8S:
448.1251. Found: 448.1254.
water, 0.2% NH3; column: Waters Xbridge Prep C18 5
m
m OBDÔ
4.8.6. 50-O-(N-Serinylphosphate)sulfamoyladenosine (13f). Following
the general procedure compound 12f (30 mg, 0.03 mmol) was hy-
19ꢁ150 mm) or Method Two (mobile phase; gradient 0e20%
MeCN in water, 0.01% TFA; Column: Waters Xbridge Prep C18
drogenated to yield 13f (12 mg, 77%) as a white foam (HPLC Method
20
5
m
m 10ꢁ150 mm).
One). [
a]
ꢂ0.07 (c 0.42, DMSO). nmax (DMSO) 3440, 3250, 3070,
D
2920, 2250, 2120, 2000, 1620 cmꢂ1. 1H NMR (D2O)
d 3.66 (1H, t, J
4.8.1. 50-O-(N-Valinyl)sulfamoyladenosine (13a). Following the
general procedure compound 12a (30 mg, 0.03 mmol) was hydro-
6.1 Hz), 4.29e4.23 (1H, m), 4.47e4.21 (3H, m), 4.51e4.47 (1H, m),
4.67e4.62 (1H, m), 4.75e4.69 (1H, m), 6.11 (1H, d, J 5.2 Hz), 8.35
(1H, s), 8.49 (1H, s). dC (100 MHz; D2O) 52.71, 58.73, 62.10, 70.10,
72.83, 82.14, 95.88, 119.41, 149.52, 152.42, 156.07, 175.33. HRMS m/z
[MþH]þ calculated for C13H18N7O11PSþ2Naþ: 558.3485. Found,
558.3487.
genated to yield 13a (8 mg, 58%) as a white foam (HPLC Method
20
Two). [
a
]
ꢂ0.10 (c 0.42, DMSO). nmax (DMSO) 3440, 3250, 3070,
D
2250, 2130, 1620, 1310, 1220 cmꢂ1 1H NMR (D2O)
. d 0.7e0.11 (6H,
m), 2.18e2.23 (1H, m), 3.75 (1H, d, J 6.2 Hz), 4.46e4.21 (3H, m), 4.51
(1H, d, J 4.5 Hz), 4.72 (1H, t, J 5.3 Hz), 6.15 (1H, d, J 5.3 Hz), 8.29 (1H,
s), 8.39 (1H, s). dC (100 MHz; D2O): 18.31, 18.35, 31.11, 58.13, 62.4,
69.4, 73.02, 82.11, 96.81, 119.01, 140.25, 149.27, 152.40, 156.91,
174.80. HRMS m/z [MþH]þ calculated for C15H23N7O7S: 446.1458.
Found: 446.1461.
4.8.7. 50-O-(N-Tyrosyl)sulfamoyladenosine (13g). Following the
general procedure compound 12g (40 mg, 0.04 mmol) was
hydrogenated to yield 13g (13 mg, 66%) as
a white foam
20
(HPLC Method Two). [
a
]
ꢂ0.08 (c 0.42, DMSO). nmax (DMSO)
D
3440, 3250, 3070, 2920, 2250, 2130, 2000, 1620 cmꢂ1. LCMS
4.8.2. 50-O-(N-Lysinyl)sulfamoyladenosine (13b). Following the
general procedure compound 12b (30 mg, 0.03 mmol) was hy-
ESIþ¼510.5. NMR data were in agreement with published data.11
drogenated to yield 13b (5 mg, 36%) as a white foam (HPLC Method
4.8.8. 50-O-(N-Tryptophanyl)sulfamoyladenosine (13h). Following
the general procedure compound 12h (30 mg, 0.03 mmol) was
hydrogenated to yield 13h (10 mg, 60%) as a white foam (HPLC
20
Two). [
a
]
ꢂ0.04 (c 0.42, DMSO). nmax (DMSO) 3440, 3270, 3070,
D
2970, 2870, 2250, 2130, 1770 cmꢂ1. 1H NMR (D2O)
m), 1.47e1.54 (2H, m), 1.78e182 (2H, m), 2.63e2.70 (2H, m), 3.59
d 1.19e1.26 (2H,
Method Two). [
a]
20 ꢂ0.05 (c 0.42, DMSO). nmax (DMSO) 3510, 3470,
D

1514
I.N. Redwan et al. / Tetrahedron 68 (2012) 1507e1514
3010, 2920, 2250, 2130, 2000, 1670 cmꢂ1. LCMS ESIþ¼534.6 NMR
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