First regioselective enzymatic acylation of amino groups applied to pyrimidine 3′,5′-diaminonucleoside derivatives. Improved synthesis of pyrimidine 3′,5′-diamino-2′,3′,5′-trideoxynucleosides

Full text of DOI:10.1021/jo010048a

J . Org. Chem. 2001, 66, 4079-4082
4079
Sch em e 1a
F ir st Regioselective En zym a tic Acyla tion
of Am in o Gr ou p s Ap p lied to P yr im id in e
3′,5′-Dia m in on u cleosid e Der iva tives.
Im p r oved Syn th esis of P yr im id in e
3′,5′-Dia m in o-2′,3′,5′-tr id eoxyn u cleosid es
Iva´n Lavandera, Susana Ferna´ndez,
Miguel Ferrero, and Vicente Gotor*
Departamento de Quı´mica Orga´nica e Inorga´nica, Facultad
de Quı´mica, Universidad de Oviedo, 33071-Oviedo, Spain
VGS@sauron.quimica.uniovi.es
Received J anuary 17, 2001
The chemistry of natural nucleosides and their ana-
logues has been widely studied due to their potential as
fungicidal, antitumor, and antiviral agents.1 Conse-
quently, extensive modifications have been made to both
the heterocyclic base and the sugar moiety in order to
avoid the drawbacks shown by nucleosides or analogues
in certain applications.
For organic chemists, enzymatic-catalyzed reactions
have become standard procedures for nucleoside modi-
fication, since they avoid the time-consuming protection
and deprotection steps required by the occurrence of
various hydroxyl groups in the sugar skeleton of the
natural nucleosides.2
a
Reaction conditions for B ) T (in parentheses for B ) U): (a)
MeSO2Cl, Py, 0 °C, 15 h, 89% (13 h, 91%); (b) Et3N, EtOH, 80 °C,
18 h, 86% (20 h, 86%); (c) NaN3, DMF 130 °C, 6 h 92% (120 °C, 5
h, 62%); (d) H2, Pd/C, EtOH, rt, 24 h, 90% (21 h, 85%).
Treatment of thymidine (1) with methanesulfonyl
chloride in pyridine at 0 °C afforded the disulfonate 3
(Scheme 1). When this dimesyl derivative was heated
under reflux with an excess of Et3N in EtOH solution,
anhydronucleoside 5 was isolated in 86% yield. The
diazido derivative 7 was obtained by treatment of 5 with
sodium azide in DMF solution at 130 °C. Hydrogenation
of 7 in EtOH in the presence of 10% Pd/C afforded 3′,5′-
diamino-3′,5′-dideoxythymidine (9) through a four-step
sequence with 63% overall yield.
The 3′,5′-diamino analogues of thymidine3 and 2′-
deoxyuridine4 have been synthesized previously, and they
showed a complete lack of either antiviral or antineoplas-
tic activity. It is known that in some cases a simple
acylation of one of the hydroxyl groups in a nucleoside
can result in an increase of their biological activity
compared with the unmodified derivative.5
Regioselective protection of one of the primary amino
groups situated in the 3′- or 5′-positions is a very difficult
task, since traditional chemical methods do not distin-
guish between them, and moreover, there are other
reactive points on the molecule such as the nitrogen
atoms on the bases.
It is the purpose of this paper to report the regiose-
lective enzymatic acylation of the amino groups in the
sugar moiety of pyrimidine 3′,5′-diaminonucleosides as
well as to show improved syntheses of the starting
materials, 3′,5′-diamino-3′,5′-dideoxythymidine and 3′,5′-
diamino-2′,3′,5′-trideoxyuridine, on the basis of its fewer
steps and high overall yields.
The same strategy was applied to prepare 3′,5′-di-
amino-2′,3′,5′-trideoxyuridine (10). In this case, nucleo-
philic displacement with NaN3 on anhydronucleoside 6
was carried out at 120 °C, since higher reaction temper-
atures gave decomposition products and lower ones
provided just 5′-OMs displacement without anhydro-
nucleoside opening. Despite moderate yield of this step,
we obtained diamino nucleoside 10 in four steps with 41%
overall yield, almost double that described in the litera-
ture.4
We have previously reported that oxime esters are good
acylating agents in regioselective enzymatic acylations
of nucleosides.6 Since amines are much more nucleophilic
than alcohols, they react nonenzymatically with oxime
esters. To solve this problem, nonactivated esters, such
as alkyl esters, were used. The studies of enzymatic
acylation focused on 3′,5′-diamino-3′,5′-dideoxythymidine
(9, Scheme 2).
(1) (a) MacCoss, M.; Robins, M. J . In Chemistry of Antitumor Agents;
Wilman, D. E. V., Ed.; Blackie and Son: U.K., 1990; p 261. (b) Robins,
R. K.; Kini, G. D. In Chemistry of Antitumor Agents; Wilman, D. E.
V., Ed.; Blackie and Son: U.K., 1990; p 299. (c) Robins, R. K.; Revankar,
G. R. In Antiviral Drug Development; De Clercq, E., Walker, R. T.,
Eds.; Plenum Press: New York, 1998; p 11.
(2) (a) Ferrero, M.; Gotor, V. Monatsh. Chem. 2000, 131, 585-616.
(b) Ferrero, M.; Gotor, V. Chem. Rev. 2000, 100, 4319-4347.
(3) Lin, T.-S.; Prusoff, W. H. J . Med. Chem. 1978, 21, 109-112.
(4) Lin, T.-S.; Zhou, R.-X.; Scanlon, K. J .; Brubaker, W. F., J r.; Lee,
J . J . S.; Woods, K.; Humphreys, C.; Prusoff, W. H. J . Med. Chem. 1986,
29, 681-686.
(5) (a) Hamamura, E. K.; Prystasz, M.; Verheyden, J . P. H.; Moffat,
J . G.; Yamaguchi, K.; Uchida, N.; Sato, K.; Nomura, A.; Shiratori, O.;
Takese, S.; Katagiri, K. J . Med. Chem. 1976, 19, 654-662. (b)
Hamamura, E. K.; Prystasz, M.; Verheyden, J . P. H.; Moffat, J . G.;
Yamaguchi, K.; Uchida, N.; Sato, K.; Nomura, A.; Shiratori, O.; Takese,
S.; Katagiri, K. J . Med. Chem. 1976, 19, 667-674.
The reaction was carried out with 8 equiv of ethyl
acetate in THF at 40 °C in the presence of molecular
sieves (4 Å) to avoid decomposition of the starting
material (entry 1, Table 1). Among the enzymes tested
[Candida antarctica lipase B (CAL-B), Pseudomonas
cepacia lipase (PSL), immobilized Pseudomonas cepacia
(6) Gotor, V.; Moris, F. Synthesis 1992, 626-628. (b) Moris, F.; Gotor,
V. J . Org. Chem. 1993, 58, 653-660. (c) Moris, F.; Gotor, V. Tetrahe-
dron 1993, 49, 10089-10098.
10.1021/jo010048a CCC: $20.00 © 2001 American Chemical Society
Published on Web 05/10/2001

4080 J . Org. Chem., Vol. 66, No. 11, 2001
Notes
Ta ble 2. En zym a tic Acyla tion of
3′,5′-Dia m in od eoxyu r id in e 10 in THF /P y (4.5:1, v/v)
Sch em e 2
isolated yields
acylating agent
R1
(%)
T
t
entry enzyme
R2 equiv (°C) (h) N-3′ N-5′ N-3′,5′
1
2
3
4
5
6
7
8
CAL-B Me
CAL-B
CAL-B nPr
CAL-B MeCHdCH Me 20
CAL-B Ph
PSL-C Me
Et
Et
Et
8
2
10
40
40
40
60 21
60 69
60 31 61
60 31 23
60 94 18a
7
7
7
75
48
70
67
65
19
24
8
H
20
Me 30
Et
Et
Et
50
5
50
11
40
PSL-C
H
PSL-C nPr
a
Starting material was recovered.
In an attempt to confer versatility to this enzymatic
reaction, other acyl moieties, such as formyl, alkyl,
alkenyl, or aryl, were introduced. Thus, only 2 equiv of
the more reactive ethyl formate was necessary to acylate
compound 9. Due to its higher reactivity, a lower yield
of N-5′ formyl 11a was found, in addition to a consider-
able amount of N-3′,5′-diformyl 15a (entry 3, Table 1).
In contrast, complete regioselectivity toward the N-5′
position was achieved with high yield when ethyl bu-
tyrate, methyl crotonate, and methyl benzoate were
employed (entries 4-6, Table 1). In these cases, due to
the lower reactivity of the esters, the ratios of acylating
agents were increased. Also, higher temperatures were
used to bring conversions close to 100%.
Ta ble 1. En zym a tic Acyla tion of 3′,5′-Dia m in oth ym id in e
9 in THF
isolated yields
acylating agent
R1
(%)
T
t
entry enzyme
R2 equiv (°C) (h) N-3′ N-5′ N-3′,5′
1
2
3
4
5
6
7
8
9
CAL-B Me
CAL-B Me
CAL-B
CAL-B nPr
Et
Et
Et
Et
8
8
2
40
28
40
40 32
60 31
60 75
40 48 21a
60 20 89
60 21 35 13
60 94 23 26
6
9
8
80
39
55
68
83
67
5
20
20
H
10
Interestingly, PSL-C catalyzed the acetylation of 9 with
total regioselectivity toward the N-3′ position. Fifty
equivalents of EtOAc and 60 °C was necessary to afford
compound 13b with excellent yield (entry 8, Table 1). The
1H NMR (D2O) spectrum of this monoacylnucleoside
presents a downfield shift of ca. 1 ppm on the H3′ proton
(from 3.34 ppm in 9 to 4.35 ppm in 13b), whereas H5′
almost did not change. Moreover, it was possible to
confirm the structure by 2D HMBC that showed a cross-
peak between H3′ and CdO corresponding to correlation
CAL-B MeCHdCH Me 20
CAL-B Ph
PSL-C Me
PSL-C Me
Me 30
Et
Et
Et
Et
20
50
5
PSL-C
H
47
10 PSL-C nPr
50
a
Starting material was recovered.
Ch a r t 1
3
H3′-CNCO via J CH. Lower temperatures and a lesser
amount of acylating agent led to the recovery of a
substantial quantity of unreacted starting material (entry
7, Table 1).
On the other hand, when ethyl formate or butyrate was
used, the process took place with lower selectivity (entries
9-10, Table 1). In the cases of methyl crotonate or
benzoate, which have already shown low reactivity with
CAL-B, the reaction did not occur.
When similar processes were carried out with 2′-
deoxyuridine derivative 10, parallel behavior was ob-
served. To favor solubility of the starting nucleoside,
pyridine was added as cosolvent. CAL-B kept its excellent
regioselectivity in the acylation of N-5′ position, isolating
exclusively compounds 12, except in case of ethyl formate
in which 20% of diacyl derivative 16a was obtained
(entries 1-5, Table 2).
In contrast, PSL-C showed only moderate regioselec-
tivity toward N-3′ in the case of acetylation (entry 6,
Table 2) with an isolated yield of 61% for compound 14b.
The formylation occurred with no selectivity, and the
main product was the N-3′,5′-diformyl nucleoside deriva-
tive 16a (entry 7, Table 2). Although ethyl butyrate
presented a degree of selectivity toward N-3′, the conver-
sion of the process was low even with prolonged reaction
times (entry 8, Table 2).
lipase (PSL-C), Candida rugosa lipase (CRL), and sub-
tilisin], CAL-B showed excellent regioselectivity toward
the 5′-NH2, 11b being isolated with 80% yield after flash
chromatography. The structure of this compound is
clearly ascertained from its 1H NMR (MeOH-d4) spec-
trum, which showed a downfield shift corresponding to
both H5′ protons from 2.89 to 3.23 ppm in diaminonucleo-
side 9 to 3.72 ppm in 11b. Meanwhile, H3′ did not display
any significant change. In addition, heteronuclear cor-
1
relation H-13C experiments 2D HMBC showed a cross-
peak between H5′ and CdO, which corresponds to corre-
3
lation H5′-CNCO via J CH. It is noteworthy that no N-3′
acylated derivative 13b was formed, despite both amino
groups being primary. Diacetylated derivative 15b (Chart
1) was detected as a minor product (5%). To minimize
the formation of this compound, the process was carried
out at 28 °C. However, 20% of N-3′,5′-diacetylated 15b
was obtained contrary to our expectations (entry 2, Table
1).
This enzymatic strategy allowed us to regioselectively
synthesize, for the first time, N-3′- or N-5′-acylated

Notes
J . Org. Chem., Vol. 66, No. 11, 2001 4081
3′-Am in o-5′-for m yla m in o-2′,3′,5′-tr id eoxyu r id in e (12a ):
1H NMR (MeOH-d4, 300 MHz) δ 2.35-2.55 (m, 2H, H2′), 3.50
(m, 1H, H3′), 3.77 (m, 2H, H5′), 3.92 (m, 1H, H4′), 5.90 (d, 1H,
H5, J HH ) 8.0 Hz), 6.29 (dd, 1H, H1′, J HH ) 7.1 Hz, J HH ) 4.6
Hz), 7.88 (d, 1H, H6, 3J HH ) 8.0 Hz), and 8.32 (s, 1H, HCO); MS
(ESI+, m/z) 293 [(M + K)+, 12], 277 [(M + Na)+, 100], and 255
[(M + H)+, 77].
5′-Acetyla m in o-3′-a m in o-2′,3′,5′-tr id eoxyu r id in e (12b):
1H NMR (MeOH-d4, 200 MHz) δ 2.16 (s, 3H, MeCO), 2.30-2.60
(m, 2H, H2′), 3.50 (m, 1H, H3′), 3.70 (m, 2H, H5′), 3.90 (m, 1H,
pyrimidine 3′,5′-diamino nucleoside derivatives by means
of a very simple and convenient procedure using PSL-C
or CAL-B as biocatalyst, respectively. Moreover, an
improved synthesis of pyrimidine 3′,5′-diamino-2′,3′,5′-
trideoxynucleosides has been described through a four-
step sequence and with high overall yield. A series of
N-monoacylated 3′,5′-diamino nucleosides were prepared
as potential antiviral and/or antitumor agents. The
biological activity of these derivatives will be tested, and
the results will be reported in a due course.
3
3
3
3
3
H4′), 5.90 (d, 1H, H5, J HH ) 7.9 Hz), 6.29 (dd, 1H, H1′, J HH
)
3
3
7.0 Hz, J HH ) 4.8 Hz), and 7.89 (d, 1H, H6, J HH ) 7.9 Hz); MS
(ESI+, m/z) 291 [(M + Na)+, 100], and 269 [(M + H)+, 73).
3′-Am in o-5′-bu tyr yla m in o-2′,3′,5′-tr id eoxyu r id in e (12c):
Exp er im en ta l Section 7
1H NMR (MeOH-d4, 300 MHz) δ 1.14 (t, 3H, H4′′ 3J HH ) 7.4
,
Gen er a l Meth od s. C. antarctica lipase B (CAL-B, 7300 PLU/
g) was a gift from Novo Nordisk Co. Immobilized P. cepacia
lipase (PSL-C, 783 U/g) was purchased from Amano Pharma-
ceutical Co.
Hz), 1.83 (m, 2H, H3′′), 2.35-2.55 (m, 4H, H2′ + H2′′), 3.50 (m,
1H, H3′), 3.71 (m, 2H, H5′), 3.90 (m, 1H, H4′), 5.89 (d, 1H, H5,
3J HH ) 8.0 Hz), 6.28 (dd, 1H, H1′, 3J HH ) 7.4 Hz, 3J HH ) 4.6 Hz),
3
and 7.91 (d, 1H, H6, J HH ) 8.0 Hz); MS (ESI+, m/z) 319 [(M +
Na)+, 100], and 297 [(M + H)+, 71].
Gen er a l P r oced u r e for th e En zym a tic Acyla tion of 3′,5′-
Dia m in on u cleosid es. Corresponding ester (ethyl formate,
ethyl acetate, ethyl butyrate, methyl crotonate, and methyl
benzoate) was added to a suspension of diaminonucleoside (20
mg, 0.08 mmol, in the case of 10 it was previously dissolved in
1 mL of dry pyridine), lipase (10 mg of CAL-B or 130 mg of PSL-
C), and molecular sieves 4 Å (20 mg) in dry THF (4.5 mL) under
nitrogen, and the mixture was stirred at 250 rpm (temperature
and reaction time are indicated in Tables 1 and 2). Then, the
enzyme and molecular sieves were filtered off and washed with
MeOH (3 × 5 mL). The filtrate was evaporated to dryness, and
the crude residue was purified by flash chromatography column
(gradient eluent 10% MeOH/EtOAc-MeOH for compounds 11a -
e, 12a -e and gradient eluent 10% MeOH/EtOAc-MeOH-10%
NH3(aq)/MeOH for compounds 13a -c, 14a -c).
3′-Am in o-5′-cr oth on ylam in o-2′,3′,5′-tr ideoxyu r idin e (12d):
1H NMR (MeOH-d4, 300 MHz) δ 2.05 (dd, 3H, H4′′
,
3J HH ) 6.8
4
Hz, J HH ) 1.7 Hz), 2.35-2.55 (m, 2H, H2′), 3.50 (m, 1H, H3′),
3
3.75 (m, 2H, H5′), 3.92 (m, 1H, H4′), 5.87 (d, 1H, H5, J HH ) 8.0
Hz), 6.16 (dq, 1H, H2′′, 3J HH ) 15.1 Hz, 4J HH ) 1.7 Hz), 6.28 (dd,
3
3
3
1H, H1′, J HH ) 7.1 Hz, J HH ) 4.6 Hz), 7.00 (dq, 1H, H3′′, J HH
3
3
) 15.1 Hz, J HH ) 6.8 Hz), and 7.87 (d, 1H, H6, J HH ) 8.0 Hz);
MS (ESI+, m/z) 317 [(M + Na)+, 100], and 295 [(M + H)+, 50].
3′-Am in o-5′-ben zoyla m in o-2′,3′,5′-tr id eoxyu r id in e (12e):
1H NMR (MeOH-d4, 300 MHz) δ 2.39-2.59 (m, 2H, H2′), 3.59
(m, 1H, H3′), 3.93 (m, 2H, H5′), 4.03 (m, 1H, H4′), 5.79 (d, 1H,
3
3
3
H5, J HH ) 8.0 Hz), 6.29 (dd, 1H, H1′, J HH ) 7.1 Hz, J HH ) 4.0
3
Hz), 7.63-7.77 (m, 3H, Hm + Hp), 7.94 (d, 1H, H6, J HH ) 8.0
Hz), and 8.05 (m, 2H, Ho); MS (ESI+, m/z) 369 [(M + K)+, 15],
353 [(M + Na)+, 100], and 331 [(M + H)+, 97].
3′-Am in o-5′-for m yla m in o-3′,5′-d id eoxyth ym id in e (11a ):
1H NMR (MeOH-d4, 300 MHz) δ 2.09 (s, 3H, H7), 2.32-2.55 (m,
2H, H2′), 3.55 (m, 1H, H3′), 3.76 (m, 2H, H5′), 3.90 (m, 1H, H4′),
5′-Am in o-3′-for m yla m in o-3′,5′-d id eoxyth ym id in e (13a ):
1H NMR (D2O, 200 MHz) δ 1.70 (s, 3H, H7), 2.25-2.50 (m, 2H,
H2′), 3.04-3.29 (m, 2H, H5′), 3.92 (m, 1H, H4′), 4.42 (m, 1H, H3′),
3
3
6.33 (dd, 1H, H1′, J HH ) 7.1 Hz, J HH ) 4.8 Hz), 7.68 (s, 1H,
H6), and 8.33 (s, 1H, HCO); MS (ESI+, m/z) 291 [(M + Na)+,
100], and 269 [(M + H)+, 76].
3
3
5.97 (dd, 1H, H1′, J HH ) 7.9 Hz, J HH ) 4.7 Hz), 7.31 (s, 1H,
H6), and 7.92 (s, 1H, HCO); MS (ESI+, m/z) 291 [(M + Na)+, 2],
and 269 [(M + H)+, 100].
5′-Acetyla m in o-3′-a m in o-3′,5′-d id eoxyth ym id in e (11b):
1H NMR (MeOH-d4, 200 MHz) δ 2.09 (s, 3H, H7), 2.15 (s, 3H,
MeCO), 2.30-2.60 (m, 2H, H2′), 3.55 (m, 1H, H3′), 3.72 (m, 2H,
3′-Acetyla m in o-5′-a m in o-3′,5′-d id eoxyth ym id in e (13b):
1H NMR (D2O, 300 MHz) δ 1.77 (s, 3H, H7), 1.90 (s, 3H, MeCO),
2.31-2.52 (m, 2H, H2′), 3.12-3.33 (m, 2H, H5′), 3.99 (m, 1H, H4′),
3
3
H5′), 3.88 (m, 1H, H4′), 6.30 (dd, 1H, H1′, J HH ) 7.3 Hz, J HH
)
4.8 Hz), and 7.68 (s, 1H, H6); MS (FAB+, m/z) 283 [(M + H)+,
15], 245 (4), 180 (14), and 140 (47).
3
3
4.35 (m, 1H, H3′), 6.04 (dd, 1H, H1′, J HH ) 7.7 Hz, J HH ) 5.1
Hz), and 7.38 (s, 1H, H6); MS (ES+, m/z) 283 (M+, 100), 241 (4),
158 (23), 99 (17), and 60 (21); MS (ESI+, m/z) 283 [(M + H)+,
100].
3′-Am in o-5′-bu tyr yla m in o-3′,5′-d id eoxyth ym id in e (11c):
1H NMR (MeOH-d4, 200 MHz) δ 1.14 (t, 3H, H4′′ 3J HH ) 7.3
,
Hz), 1.83 (m, 2H, H3′′), 2.09 (s, 3H, H7), 2.30-2.57 (m, 4H, H2′
+
5′-Am in o-3′-bu tyr yla m in o-3′,5′-d id eoxyth ym id in e (13c):
1H NMR (MeOH-d4, 300 MHz) δ 1.14 (t, 3H, H4′′
,
3J HH ) 7.4
H2′′), 3.55 (m, 1H, H3′), 3.70 (m, 2H, H5′), 3.87 (m, 1H, H4′), 6.30
3
3
3
(dd, 1H, H1′, J HH ) 7.0 Hz, J HH ) 4.8 Hz), and 7.65 (s, 1H,
H6); MS (ESI+, m/z) 333 [(M + Na)+, 82], and 311 [(M + H)+,
100).
Hz), 1.83 (m, 2H, H3′′), 2.10 (s, 3H, H7), 2.38 (t, 2H, H2′′, J HH
)
7.1 Hz), 2.42-2.64 (m, 2H, H2′), 3.02-3.17 (m, 2H, H5′), 3.91 (m,
1H, H4′), 4.58 (m, 1H, H3′), 6.37 (dd, 1H, H1′, 3J HH ) 7.1 Hz, 3J HH
) 5.7 Hz), and 7.75 (s, 1H, H6); MS (ESI+, m/z) 349 [(M + K)+,
15], 333 [(M + Na)+, 33], and 311 [(M + H)+, 100].
3′-Am in o-5′-cr oth on ylam in o-3′,5′-dideoxyth ym idin e (11d):
1H NMR (MeOH-d4, 300 MHz) δ 2.05 (m, 6H, H4′′ + H7), 2.33-
2.53 (m, 2H, H2′), 3.55 (m, 1H, H3′), 3.79 (m, 2H, H5′), 3.90 (m,
1H, H4′), 6.17 (dq, 1H, H2′′, 3J HH ) 15.1 Hz, 4J HH ) 1.4 Hz), 6.29
5′-Am in o-3′-for m yla m in o-2′,3′,5′-tr id eoxyu r id in e (14a ):
1H NMR (D2O, 300 MHz) δ 2.52-2.73 (m, 2H, H2′), 3.29-3.49
(m, 2H, H5′), 4.16 (m, 1H, H4′), 4.61 (m, 1H, H3′), 5.91 (d, 1H,
3
3
(dd, 1H, H1′, J HH ) 7.1 Hz, J HH ) 4.3 Hz), 7.01 (dq, 1H, H3′′
,
3J HH ) 15.1 Hz, 3J HH ) 6.8 Hz), and 7.64 (s, 1H, H6); MS (ESI+,
H5, J HH ) 8.3 Hz), 6.18 (dd, 1H, H1′, J HH ) 7.7 Hz, J HH ) 5.1
Hz), 7.74 (d, 1H, H6, 3J HH ) 8.3 Hz), and 8.15 (s, 1H, HCO); MS
(ESI+, m/z) 277 [(M + Na)+, 5], and 255 [(M + H)+, 100].
3′-Acetyla m in o-5′-a m in o-2′,3′,5′-tr id eoxyu r id in e (14b):
1H NMR (D2O, 300 MHz) δ 1.89 (s, 3H, MeCO), 2.29-2.53 (m,
2H, H2′), 3.07-3.26 (m, 2H, H5′), 3.96 (m, 1H, H4′), 4.33 (m, 1H,
3
3
3
m/z) 331 [(M + Na)+, 100], and 309 [(M + H)+, 75].
3′-Am in o-5′-ben zoyla m in o-3′,5′-d id eoxyth ym id in e (11e):
1H NMR (MeOH-d4, 300 MHz) δ 1.90 (s, 3H, H7), 2.37-2.57 (m,
2H, H2′), 3.62 (m, 1H, H3′), 3.95 (m, 1H, H4′), 4.02 (m, 2H, H5′),
3
3
6.31 (dd, 1H, H1′, J HH ) 7.4 Hz, J HH ) 4.3 Hz), 7.63-7.77 (m,
4H, H6 + Hm + Hp), and 8.05 (m, 2H, Ho); MS (ESI+, m/z) 383
[(M + K)+, 7], 367 [(M + Na)+, 100], and 345 [(M + H)+, 94].
3
3
H3′), 5.75 (d, 1H, H5, J HH ) 8.3 Hz), 6.03 (dd, 1H, H1′, J HH
)
3
3
7.7 Hz, J HH ) 5.4 Hz), and 7.58 (d, 1H, H6, J HH ) 8.3 Hz); MS
(ESI+, m/z) 291 [(M + Na)+, 3], and 269 [(M + H)+, 100].
5′-Am in o-3′-bu tyr yla m in o-2′,3′,5′-tr id eoxyu r id in e (14c):
1H NMR (D2O, 300 MHz) δ 0.89 (t, 3H, H4′′, 3J HH ) 7.4 Hz), 1.60
(m, 2H, H3′′), 2.24 (t, 2H, H2′′, 3J HH ) 7.4 Hz), 2.40-2.68 (m, 2H,
H2′), 3.23-3.42 (m, 2H, H5′), 4.10 (m, 1H, H4′), 4.48 (m, 1H, H3′),
5.87 (d, 1H, H5, 3J HH ) 8.0 Hz), 6.14 (dd, 1H, H1′, 3J HH ) 6.2 Hz,
(7) Compounds 3,8 4,9 5,8 6,10 7,3 8,4 9,3 and 104 were previously
reported; experimental procedures and 1H and 13C NMR data are given
in the Supporting Information. For compounds 11-16, full spectral
data and copies of 1H and 13C NMR spectra are given in the Supporting
Information. The level of purity is indicated by the inclusion of
elemental analyses.
(8) Michelson, A. M.; Todd, A. R. J . Chem. Soc. 1955, 816-823.
(9) Horwitz, J . P.; Chua, J .; Da Rooge, M. A.; Noel, M.; Klundt, I. L.
J . Org. Chem. 1966, 31, 205-211.
(10) Horwitz, J . P.; Chua, J .; Noel, M.; Donatti, J . T. J . Org. Chem.
1967, 32, 817-818.
3J HH ) 5.1 Hz), and 7.70 (d, 1H, H6, J HH ) 8.0 Hz); MS (ESI+,
3
m/z) 319 [(M + Na)+, 7], and 297 [(M + H)+, 100].
3′,5′-Difor m ylam in o-3′,5′-dideoxyth ym idin e (15a): 1H NMR
(MeOH-d4, 300 MHz) δ 2.10 (s, 3H, H7), 2.47-2.70 (m, 2H, H2′),
3.65-3.89 (m, 2H, H5′), 4.11 (m, 1H, H4′), 4.62 (m, 1H, H3′), 6.34

4082 J . Org. Chem., Vol. 66, No. 11, 2001
Notes
3
3
(dd, 1H, H1′, 3J HH ) 7.1 Hz), 7.73 (s, 1H, H6), 8.28 (s, 1H, HCO),
and 8.31 (s, 1H, HCO); MS (ESI+, m/z) 335 [(M + K)+, 10], 319
[(M + Na)+, 100], and 297 [(M + H)+, 1].
5.92 (d, 1H, H5, J HH ) 8.3 Hz), 6.31 (dd, 1H, H1′, J HH ) 6.4
Hz), and 7.92 (d, 1H, H6, J HH ) 8.3 Hz); MS (ESI+, m/z) 349
3
[(M + K)+, 6], and 333 [(M + Na)+, 100].
3′,5′-Diacetylam in o-3′,5′-dideoxyth ym idin e (15b): 1H NMR
(MeOH-d4, 300 MHz) δ 2.10 (s, 3H, H7), 2.16 (s, 6H, MeCO),
2.30-2.70 (m, 2H, H2′), 3.60-3.80 (m, 2H, H5′), 4.05 (m, 1H, H4′),
Ack n ow led gm en t. Financial support from CICYT
(Spain; Project BIO98-0770) is gratefully acknowledged.
We also thank the Ministerio de Educacio´n y Cultura
(Spain) for a predoctoral (I.L.) and a postdoctoral (S.F.)
fellowship. We express our appreciation to Novo Nordisk
Co. for the generous gift of the lipase CAL-B.
3
3
4.50 (m, 1H, H3′), 6.32 (dd, 1H, H1′, J HH ) 6.9 Hz, J HH ) 6.0
Hz), and 7.70 (s, 1H, H6); MS (ESI+, m/z) 363 [(M + K)+, 11],
and 347 [(M + Na)+, 100].
3′,5′-Difor m ylam in o-2′,3′,5′-tr ideoxyu r idin e (16a): 1H NMR
(MeOH-d4, 300 MHz) δ 2.53-2.70 (m, 2H, H2′), 3.62-3.90 (m,
2H, H5′), 4.11 (m, 1H, H4′), 4.61 (m, 1H, H3′), 5.92 (d, 1H, H5,
3
3J HH ) 8.3 Hz), 6.33 (dd, 1H, H1′, J HH ) 7.1 Hz), 7.92 (d, 1H,
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures and complete 1H and 13C NMR spectral data in
addition to mp, IR, microanalysis, and MS data. This material
is available free of charge via the Internet at http://pubs.acs.org.
3
H6, J HH ) 8.3 Hz), 8.29 (s, 1H, HCO), and 8.30 (s, 1H, HCO);
MS (ESI+, m/z) 321 [(M + K)+, 10], and 305 [(M + Na)+, 100].
3′,5′-Diacetylam in o-2′,3′,5′-tr ideoxyu r idin e (16b): 1H NMR
(MeOH-d4, 200 MHz) δ 2.16 (s, 6H, MeCO), 2.47-2.62 (m, 2H,
H2′), 3.60-3.82 (m, 2H, H5′), 4.10 (m, 1H, H4′), 4.51 (m, 1H, H3′),
J O010048A