Synthesis of [5'-13C]ribonucleosides and 2'-deoxy[5'-13C]ribonucleosides.

Article abstract of DOI:10.1021/jo016281q

The present efficient synthesis of [5'-13C]ribonucleosides and 2'-deoxy[5'-13C]ribonucleosides is characterized by the synthesis of the D-[5-13C]ribose derivative as an intermediate via the Wittig reaction of 4-aldehydo-D-erythrose dialkyl acetals with Ph3P13CH3I-BuLi to introduce the 13C label at the 5-position of a pentose. This was followed by the highly diastereoselective osmium dihydroxylation for the preparation of 2,3-di-O-benzyl-D-[5-13C]ribose dialkyl acetal and the cyclization from D-[5-13C]ribose dialkyl acetal derivatives to the alkyl D-[5-13C]ribofuranoside derivative by the use of LiBF(4). The obtained D-[5-13C]ribose derivative was converted into [5'-13C]ribonucleosides and subsequently into the corresponding 2'-deoxynucleosides.

Full text of DOI:10.1021/jo016281q

Syn th esis of [5′-13C]Ribon u cleosid es a n d
2′-Deoxy[5′-13C]r ibon u cleosid es
Etsuko Kawashima,* Kaoru Umabe, and Takeshi Sekine
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, Tokyo University of Pharmacy and Life
Science, Horinouchi, Hachioji, Tokyo, 192-0392 J apan
kawasima@ps.toyaku.ac.jp
Received November 14, 2001
The present efficient synthesis of [5′-13C]ribonucleosides and 2′-deoxy[5′-13C]ribonucleosides is
characterized by the synthesis of the D-[5-13C]ribose derivative as an intermediate via the Wittig
reaction of 4-aldehydo-D-erythrose dialkyl acetals with Ph3P13CH3I-BuLi to introduce the 13C label
at the 5-position of a pentose. This was followed by the highly diastereoselective osmium
dihydroxylation for the preparation of 2,3-di-O-benzyl-D-[5-13C]ribose dialkyl acetal and the
cyclization from D-[5-13C]ribose dialkyl acetal derivatives to the alkyl D-[5-13C]ribofuranoside
derivative by the use of LiBF4. The obtained D-[5-13C]ribose derivative was converted into [5′-13C]-
ribonucleosides and subsequently into the corresponding 2′-deoxynucleosides.
In tr od u ction
Serianni et al.,5 respectively. Matwiyoff et al.4 prepared
[5′-13C]adenosine by the coupling reaction of an adenine
derivative with a D-[5-13C]ribose derivative, which was
synthesized by way of L-[1-13C]ribonic acid obtained by
the reaction of L-erythrose with K13CN, followed by
hydrolysis under acidic conditions. Serianni et al.,5 on
the other hand, synthesized D-[5-13C]ribose from D-[6-13C]-
glucose, which was obtained by the reaction of 1,2-O-
isopropylidene-R-D-xylo-pentdialdo-1,4-furanoside with
K13CN. These synthetic methods, however, inevitably
involved multiple steps after the introduction of the 13C
label to attain the final product and were therefore
judged impractical. Thus, more efficient processes were
needed to prepare [5′-13C]nucleosides. We have published
a letter6 and a short communication7 regarding the
efficient synthesis of 2′-deoxy[5′-13C]ribonucleosides. The
detailed results thus obtained are described herein.
The conformational diversity of the sugar-phosphate
backbone and/or the sugar moieties in nucleic acids is
considered to be important in the elucidation of nucleic
acid-protein or -medicine recognition processes. An
efficient synthetic method for 2′-deoxy[5′-2H]ribonucleo-
sides (5′S/5′R ) ca. 2:1)1 has been developed, with the
expectation that this would enable us to assign unam-
biguously both the H5′ and H5′′ signals of an oligodeox-
yribonucleotide and to determine its sugar-phosphodi-
ester backbone conformation spectroscopically by NMR.
NOESY and DQF-COSY NMR analyses of the decamer
d(G*C*A*T*T*A*A*T*G*C*) bearing these deuterium-
labeled nucleotides were performed. The complete ste-
reospecific assignments and the simplified spin systems
enabled us to determine the 15 3J coupling constants
between H4′ and H5′/H5′′ and to assign unambiguously
135 NOESY cross-peaks originating from H4′/H5′/H5′′
resonances.2 In addition, the duplex d(C*G*C*G*A*-
A*T*T*C*G*C*G*)2 constructed from these labeled com-
Resu lts a n d Discu ssion
I. Syn t h esis of 1-O-Acet yl-2,3,5,-t r i-O-b en zoyl-D-
[5-13C]r ibofu r a n ose fr om D-Ribose. The first step for
the synthesis of [5′-13C]nucleosides was the synthesis of
1-O-Ac-2,3,5-tri-O-benzoyl-D-[5-13C]ribofuranose (12) from
D-ribose (1) via D-[5-13C]ribose dialkyl acetal derivatives
(7).
Syn th esizin g th e Su bstr a te To In tr od u ce th e
Ca r bon -13 La bel a t th e 5 P osition of D-Ribose
(Sch em e 1). The chemical conversion of D-ribose (1) into
4-aldehydo-2,3-di-O-benzyl-D-erythrose dibenzyl acetal
(5-Bn ) and the corresponding dimethyl acetal (5-Me),
ponents proved their utility in 2D H-31P HSQC.3
1
From another point of view, the site-specific labeling
of the 5′ position of nucleosides with 13C could facilitate
conformational studies of an oligonucleotide chain, in
terms of heteronuclear multidimensional NMR spectros-
copy.
The chemical syntheses of [5′-13C]adenosine and D-[5-
13C]ribose have been reported by Matwiyoff et al.4 and
(1) (a) Kawashima, E.; Toyama, K.; Ohshima, K.; Kainosho, M.;
Kyogoku, Y.; Ishido, Y. Chirality 1997, 9(5/6), 435-442. (b) Ka-
washima, E., Toyama, K., Ohshima, K., Kainosho, M.; Kyogoku, Y.;
Ishido, Y. Tetrahedron Lett. 1995, 36, 6699-6700.
(2) Kojima, C.; Kawashima, E.; Toyama, K.; Ohshima, K.; Ishido,
Y.; Kainosho, M.; Kyogoku, Y. J . Biomol. NMR 1998, 11, 103-109.
(3) Ono, A.; Makita, T.; Tate, S.; Kawashima, E.; Ishido, Y.;
Kainosho, M. Magn. Reson. Chem. 1996, 34, s40-s46.
(5) Serianni, A. S.; Bondo, P. B. J . Biomol. Struct. Dyn. 1994, 11,
1133-1148.
(6) Sekine, T.; Kawashima, E.; Ishido, Y. Tetrahedron Lett. 1996,
37. 7757-7760.
(7) Kawashima, E.; Sekine, T.; Umabe, K.; Naito, Y.; Kamaike, K.;
Kojima, C.; Mizukoshi, T.; Suzuki, E.; Ishido, Y. Nucleosides Nucle-
otides 1999, 18, 1597-1598.
(4) Walker, T. E.; Hogenkemp, H. P. C.; Needham, T. E.; Matwiyoff,
N. A. Biochemistry 1974, 13, 2650-2655.
10.1021/jo016281q CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/19/2002
5142
J . Org. Chem. 2002, 67, 5142-5151

Synthesis of [5′-13C]Ribonucleosides
SCHEME 1. Syn th esis of th e Su bstr a te for In tr od u cin g th e 13C La bel a t th e 5 P osition of D-Ribosea
a
Reagent and conditions: (a) methyl ribosylation, 5-O-dimethoxytritylation, 2,3-di-O-benzylation, dedimethoxytritylation at the 5
position; (b) EtSH, concd HCl, 0 °C by the method of Stahley et al.;8 (c) ROH (benzyl and methyl alcohol), HgO, HgCl2, CaSO4, 70 °C by
the method of Serfontein et al.;9 (d) 4-Bn : NaIO4, 5 mM H2SO4 in EtOH/H2O (9/1), rt; 4-Me: NaIO4 in EtOH/H2O (9/1), rt.
SCHEME 2. In tr od u ction of th e 13C-La bel a t th e
C5 by th e Wittig Rea ction
TABLE 1. OsO4 Dih yd r oxyla tion Rea ction of 6′-Bn
(Non la beled )
7′-Bn
(nonlabeled)
procedure
reagents
yield (%)
4R/4S
stoichiometric OsO4 (1.2 mol equiv)
pyridine
97
92:8
catalytic
OsO4 (0.05 mol equiv)
4-methylmorpholine
N-oxide
97
93:7
Ribose Der iva tive (Sch em es 3 a n d 4). In the next
step, we investigated the diastereoselective dihydroxy-
lation of 6. The asymmetric dihydroxylation (AD) reac-
tion11 of 6 with osmium tetraoxide (OsO4), as well as the
introduction of the carbon-13 label by the Wittig reaction,
was also one of the important key steps in this synthetic
route. By the use of nonlabeled 2,3-di-O-benzyl-4,5-
didehydro-4,5-dideoxy-D-ribose dibenzyl acetal (6′-Bn ),
the reaction conditions were examined through two
routes of stoichiometric12a (osmium tetraoxide 1.2 mol
equiv in pyridine) and catalytic12b (osmium tetraoxide
0.05 mol equiv and 4-methylmorpholine N-oxide) proce-
dures. Both of the reactions gave a mixture of 2,3-di-O-
benzyl-D-ribose dibenzyl acetal (7′-Bn ) (3,4-anti; 4R) and
L-lyxo (3,4-syn; 4S) isomer, with the ratios of 92:8 and
93:7 in 97% yield, respectively (Table 1). The confirmation
of structures and the proportions of these products were
which are the substrates to introduce the carbon-13 label
at the 5 position of D-ribose by the Wittig reaction using
a [13C]methyltriphenylphosphonium iodide (Ph3P13CH3I),
was efficiently performed by the sequence reactions
shown in Scheme 1. Compound 1 was successfully
converted into 5-Bn in 69% and 5-Me in 75% overall
yields in nine steps, respectively.
In tr od u ction of th e 13C La bel a t th e 5-P osition of
a D-Ribofu r a n ose Der iva tive (Sch em e 2). The intro-
duction of the carbon-13 label proceeded by the Wittig
reaction,10 using a Ph3P13CH3I-butyllithium (BuLi) sys-
tem to give 2,3-di-O-dibenzyl-4,5-didehydro-4,5-dideoxy-
D-[5-13C]ribofuranose dibenzyl acetal (6-Bn ) and dimethyl
acetal (6-Me) in excellent yields of 93% and 94%,
respectively (Scheme 2).
1
determined by comparison with 4-Bn and by H NMR
spectroscopy after their conversion into the 4,5-di-O-
benzoyl derivatives 8 (Scheme 3 and Table 1).
1
The H NMR chart of 6-Bn is shown in Figure 1, along
with that of the corresponding nonlabeled sample, which
demonstrates its reasonable structure by comparing that
of the corresponding nonlabeled sample with respect to
the H5 signal region. Only the C5 signal was recognized
in the C-13 NMR chart of 6-Bn in Figure 2. A comparison
of these spectra shows the introduction of the 13C label
at the 5-position of 6-Bn achieved in the present work.
High ly Dia ster eoselective Dih yd r oxyla tion Rea c-
tion w ith OsO4 for th e P r ep a r a tion of th e D-[5-13C]-
The efficiency under these conditions led us to use the
catalytic procedure for the reaction of 6 to give a mixture
of the 2,3-di-O-benzyl-D-[5-13C]ribose dibenzyl acetal (7-
Bn ) and the L-lyxo isomer from 6-Bn [quenching by
sodium hydrogen sulfite (NaHSO3)] and a mixture of the
corresponding dimethyl acetal (7-Me) and the L-lyxo
isomer from 6-Me [quenching by an aqueous solution of
saturated sodium disulfite (Na2S2O5)13], in 99% (93:7) and
(8) (a) Kennea, G. W.; Robba, H. J .; Todd, A. R. J . Chem. Soc. 1949,
1613-1620. (b) Wolfrom, M. I.; Newlin, M. R.; Stahly, E. E. J . Am.
Chem. Soc. 1931, 53, 4379-4383.
(11) Kolb, H. C.; VanNieuwenhze, M. S.; Sharpless, K. B. Chem.
Rev. 1994, 94, 2483-2547.
(12) (a) Cha, J . K.; Christ, W. J .; Kishi, Y. Tetrahedron Lett. 1983,
24, 3943-3946. (b) Cha, J . K.; Christ, W. J .; Kishi, Y. Tetrahedron
1984, 40, 2247-2255.
(9) J ordaan, J . H.; Serfontein, W. J . J . Org. Chem. 1963, 1395-
1397.
(10) Matsuda, A.; Takenuki, K.; Tanaka, M.; Sasaki, T.; Ueda, T.
J . Med. Chem. 1991, 34, 812-819.
(13) Wai, J . S. M.; Marko, I.; Svendsen, J . S.; Finn, M. G.; J acobsen,
E. N.; Sharpless, K. B. J . Am. Chem. Soc. 1989, 111, 1123-1125.
J . Org. Chem, Vol. 67, No. 15, 2002 5143

Kawashima et al.
F IGURE 1. 1H NMR spectra of 2,3-di-O-benzyl-4,5-didehydro-4,5-dideoxy-D-[5-13C]ribose dibenzyl acetal (6-Bn ) (panel a) and
the corresponding nonlabeled D-ribose dibenzyl acetal 6′-Bn (panel b). The spectra of a clearly show the J network through the
H-5 and H-5′ protons and the 5-13C.
F IGURE 2. 13C NMR spectra of 2,3-di-O-benzyl-4,5-didehydro-4,5-dideoxy-D-[5-13C]ribose dibenzyl acetal (6-Bn ) (panel a) and
the corresponding nonlabeled D-ribose dibenzyl acetal 6′-Bn (panel b).
96% (92:8) total yield, respectively. The mixtures were
subjected to column chromatography again to give 7-Bn
and 7-Me in 90% and 86% yield, respectively (Scheme
4).
In this manner, the (4R)-D-[5-13C]ribose derivatives
7-Bn and 7-Me were successfully prepared as the main
products, which had 3,4-anti relationships between the
original and the newly formed stereogenic center. Al-
though these results agree with the theories proposed by
Stork14 and Houk15 regarding the AD reaction of allylic
alcohol, these excellent results in the presence of only
pyridine or 4-methylmorpholine N-oxide, without a bis-
cinchona alkaloid ligand such as (DHQD)2PHAL,16 greatly
exceeded their predictions. It was presumed that the 3,4-
anti product (4R) was predominantly produced by the
large steric hindrance arising at one side of the double
bond from the “inside alkoxy effect”.17
Syn th esis of 1-O-Acetyl-2,3,5-tr i-O-ben zoyl-D-[5-
13C]r ibose a s th e Glycosyl Don or (Sch em e 5). Next,
the chemical derivatization of (4R)-7 to the glycosyl donor
1-O-acetyl-2,3,5-tri-O-benzoyl-D-[5-13C]ribofuranose (12)
was carried out. The benzyl acetal 7-Bn was subjected
(16) Corey, E. J .; Guzman-Perez, A.; Noe, M. C. J . Am. Chem. Soc.
1994, 116, 12109-12110; 1995, 117, 10805-10816.
(17) (a) Houk, K. N.; Moses, S. R.; Wu, Y.-D.; Rondan, N. G.; J a¨ger,
V.; Schohe, R.; Fronczek, F. R. J . Am. Chem. Soc. 1984, 106, 3880-
3882. (b) Vedejs, E.; McClure, C. K. J . Am. Chem. Soc. 1986, 108,
1094-1096.
(14) Stork, G.; Kahn, M. Tetrahedron Lett. 1983, 24, 3951-3954.
(15) Haller, J .; Strassner, T.; Houk, K. N.; J . Am. Chem. Soc. 1997,
119, 8031-8034
5144 J . Org. Chem., Vol. 67, No. 15, 2002

Synthesis of [5′-13C]Ribonucleosides
SCHEME 3. High ly Dia ster eoselective Dih yd r oxyla tion of Non la beled 6′-Bn w ith OsO4 a n d Am in e
SCHEME 4. High ly Dia ster eoselective Dih yd r oxyla tion w ith OsO4 a n d Am in e
SCHEME 5. P r ep a r a tion of th e D-[5-13C]Ribofr a n ose Der iva tive
to hydrogenation to give D-[5-13C]ribose, methyl glycosy-
lation to give methyl D-[5-13C]ribofuranose, and benzoy-
lation to give methyl 2,3,5-tri-O-benzoyl-D-[5-13C]ribo-
furanoside (11), which was then subjected to acetolysis.
Thus, the glycosylating agent 12 was obtained in an
excellent yield of 98% as a 1:4 mixture of R- and
â-anomers from 11. On the other hand, 7-Me was treated
with lithium tetrafluoroborate (LiBF4) according to the
method of Harvey et al.,18 with the expectation of yielding
2,3-di-O-benzyl-D-ribose. Contrary to our expectation, this
reaction gave methyl 2,3-di-O-benzyl-D-[5-13C]ribofura-
noside (10) in 98% yield. This treatment is very useful
for the conversion of a dialkyl acetal derivative into an
alkyl D-ribofuranoside derivative. The resulting 10 was
hydrogenated for debenzylation and then was converted
into 12 via 11 by the usual method (Scheme 5).
II. Syn t h esis of 2′-Deoxy[5′-13C]r ib on u cleosid e
Der iva tives. Second, the resulting 12 was finally sub-
jected to a coupling reaction with a persilylated nucleo-
base (persilylated N6-benzoyladenine, N2-acetyl-O6-diphe-
nylcarbamoylguanine, N4-benzoylcytosine, thymine, and
uracil) with Vorbru¨ggen’s approach19 to give the [5′-13C]-
ribonucleoside derivatives (13) (99 atom % 13C) in good
yields (80%, 79%, 96%, 98%, and 78%, respectively)
(Table 2, Scheme 6). These [5′-13C]ribonucleosides are
interesting from the viewpoint of RNA science, of course,
but were further converted into the corresponding 2′-
deoxy derivatives for DNA analyses as well.
(18) Lipshutz, B. H.; Harvey, D. F. Synth. Commun. 1982, 12, 267-
277.
(19) Vorbru¨gen, H.; Krolikiewicz, K.; Bennua, B. Chem. Ber. 1981,
114, 1234-1255.
J . Org. Chem, Vol. 67, No. 15, 2002 5145

Kawashima et al.
SCHEME 6. Ch em ica l Con ver sion of a D-[5-13C]Ribose Der iva tive in to th e Cor r esp on d in g
2′-Deoxy[5′-13C]n u cleosid e Der iva tives
TABLE 2. Cou p lin g of 12 w ith P er silyla ted Nu cleoba sea
TABLE 3. Yield s (%) of Com p ou n d s 14, 15, 16, a n d 17 on
Con ver sion in to 2′-Deoxy[5′-13C]r ibon u cleosid esa
B
13 yield (%)
B
14
15
16
17
ABz
80
79
96
98
78
DPC
G
ABz
G
74
45
78
72
84
86
86
92
92
97
76
98
98
90
96
98
Ac
CBz
T
DPC
Ac
CBz
T
U
a
DPC
a
DPC
Abbreviation: ABz ) N6-Benzoyladenin-9-yl,
G
) N2-
Abbreviation: ABz ) N6-benzoyladenin-9-yl,
G
Ac
) N2-
Ac
Acetyl-O6-diphenylcarbamoylguanin-9-yl, CBz ) N2-Benzoylcy-
tosin-1-yl, T ) Thymin-1-yl, U ) Uracil-1-yl.
Acetyl-O6-diphenylcarbamoylguanin-9-yl, CBz ) N2-Benzoylcy-
tosin-1-yl, T ) Thymin-1-yl.
lowed by the deprotection of TIPDS with tetraethyl-
ammonium fluoride (Scheme 6); the yields of the reac-
tions for each 2′-deoxyribonucleoside (17) are summarized
in Table 3.
The proton and carbon-13 NMR spectra of 3′,5′-O-
TIPDS-[5′-13C]thymidine are demonstrated in Figure 3a
and b, respectively. The spectra of the other nucleosides
17 were obtained in the same way.
Compounds 13 were successfully transformed into the
corresponding 2′-deoxy[5′-13C]ribonucleoside derivatives
17 in the established manner, i.e., debenzoylation, pro-
tection of both the 3′- and 5′-hydroxyl groups with a
1,1,3,3-tetraisopropyldisiloxane-1,3-diyl (TIPDS) group,20
introduction of a phenoxythiocarbonyl group at the 2′
position,21 the reduction with tributyltin hydride,21 fol-
F IGURE 3. 1H NMR (panel a) and carbon-13 NMR (panel b) spectra of 3′,5′-O-TIPDS-[5′-13C]thymidine (16T). These spectra
clearly show the introduction of the 13C label at the 5′-position of 16T achieved in the present work.
5146 J . Org. Chem., Vol. 67, No. 15, 2002

Synthesis of [5′-13C]Ribonucleosides
mL) was added to methyl-13C-triphenylphosphonium iodide
(1.0 g, 2.5 mmol) in THF (10 mL) under an argon atmosphere
at 0 °C, and the mixture was stirred for 20 min. A solution of
5-Bn (980 mg, 2.0 mmol) in THF (10 mL) was added dropwise
to the resulting solution, and the whole was stirred for 3 h at
0 °C. The reaction was quenched by addition of 1.0 M aqueous
ammonium chloride (30 mL), which was extracted with Et2O
(50 mL × 3). The Et2O layer was washed with brine (50 mL),
dried (MgSO4), and concentrated to dryness. The residue was
subjected to silica gel column chromatography, with hexane-
AcOEt as eluent, to give 6-Bn (908 mg, 93%). 1H NMR
(CDCl3): δ 7.2-7.4 (20H, m, Ph-H), 5.96 (1H, ddd, J 3,4 ) 8.0
Con clu sion
The present synthesis of D-[5-13C]ribofuranose deriva-
tives is characterized by the introduction of the carbon-
13 label at the 5 position of D-ribose, through the Wittig
reaction using PhP13CH3I, the subsequent highly dias-
tereoselective dihydroxylation using osmium tetraoxide,
and the cyclization from D-[5-13C]ribose dimethyl acetal
derivatives to the methyl D-[5-13C]ribofuranoside deriva-
tive by the use of LiBF4. The efficiency of the present
approach from 1 to 12 is characterized by a 58% overall
yield of 12 from Ph3P13CH3I, i.e., after the introduction
of the 13C label by the Witting reaction, in contrast with
the 4% overall yield of 12 from [13C]KCN reported by
Matwiyoff et al.4 and the 25% overall yield of 9 from [13C]-
KCN reported by Serianni et al.5 after introduction of the
13C label.
Hz, J 4,5 ) 17.4 Hz, J 4,5′ ) 10.4 Hz, H4), 5.29 (1H, ddd, J 4,5′
)
10.4 Hz, J 5,5′ ) 1.9 Hz, J 5′,C5 ) 158.4 Hz, H5′), 5.17 (1H, ddd,
J 4,5 ) 17.4 Hz, J 5,5′ ) 1.9 Hz, J 5,C5 ) 155.2 Hz, H5), 4.87 (1H,
d, J ) 11.5 Hz, Bn-CH), 4.78 (1H, d, J ) 11.5 Hz, Bn-CH),
4.70 (1H, d, J 1,2 ) 6.4 Hz, H1), 4.58-4.68 (4H, m, Bn-CH x 4),
4.49 (1H, d, J ) 11.7 Hz, Bn-CH), 4.32 (1H, d, J ) 12.0 Hz,
Bn-CH), 4.10 (1H, dd, J 2,3 ) 3.3 Hz, J 3,4 ) 8.0 Hz, J 3,C5 ) 4.3
Hz, H3), 3.98 (1H, dd, J 1,2 ) 6.4 Hz, J 2,3 ) 3.3 Hz, H2). 13C
NMR (CDCl3): δ 138.80, 138.68, 138.21, 137.72, 134.99 (d, J 4,5
) 68.8 Hz), 128.36, 128.32, 128.26, 128.08, 127.93, 127.83,
127.66, 127.54, 127.38, 127.34, 119.30, 101.61, 81.69, 81.24,
74.41, 70.16, 69.51, 69.03. Anal. Calcd for C3213CH36O6‚
0.1H2O: C, 79.85; H, 6.95. Found: C, 79.75; H, 7.03.
Exp er im en ta l Section
Gen er a l P r oced u r es. Melting points were uncorrected. 1H
and 13C NMR spectra were recorded at 400 and 300 MHz and
at 100 and 75 MHz, respectively. Chemical shifts were
recorded in the δ scale relative to an internal reference of
CDCl3 (7.26 ppm for 1H NMR and 77.0 ppm for 13C NMR
spectra), unless otherwise noted. Dimethyl sulfoxide-d6 (DMSO-
d6) (2.50 ppm for 1H spectra) was occasionally used as an
internal reference. The signal peaks of the 13C NMR spectra
were assigned by the DEPT experiment. Mass spectra (MS),
high-resolution mass spectra (HRMS), and elemental analyses
were recorded at The Tokyo University of Pharmacy and Life
Science Chemical Instrumentation Center. TLC was performed
2,3-Di-O-ben zyl-4,5-d id eh yd r o-4,5-d id eoxy-D-[5-13C]r i-
bose Dim eth yl Aceta l (6-Me). Compound 5-Me (654 mg, 1.9
mmol) was treated in a manner similar to that for 5-Bn to
1
give 6-Me in 94% (612 mg) yield. H NMR (CDCl3): δ 7.39-
7.25 (10H, m, Ph-H), 5,97 (1H, ddd, J 3,4 ) 7.8 Hz, J 4,5 ) 10.1
Hz, J 4,5′ ) 17.6 Hz, H4), 5.34 (1H, ddd, J 4,5 ) 10.5 Hz, J 5,5′
)
2.0 Hz, J
) 158.1 Hz, H5), 5.30 (1H, ddd, J 4,5′ ) 18.2 Hz,
5,5C
J 5,5′ ) 2.1 Hz, J 5′,5C ) 154.9 Hz, H5′), 4.82 (1H, d, J ) 11.6 Hz,
Bn-CH), 4.76 (1H, d, J ) 11.6 Hz, Bn-CH), 4.63 (1H, d, J ) 12
Hz, Bn-CH), 4.38 (1H, d, J ) 11.9 Hz, Bn-CH), 4.31 (1H, d,
J 1,2 ) 6.1 Hz, H1), 4.03 (1H, dd, J 2,3 ) 8.2 Hz, J 3,4 ) 8.2 Hz,
H3), 3.71 (1H, dd, J 1,2 ) 6.1 Hz, J 2,3 ) 3.6 Hz, H2), 3.40 (3H,
s, OCH3), 3.35 (3H, s, OCH3). 13C NMR (CDCl3): δ 138.74,
138.57, 134.98 (d, J 4,5 ) 47.8 Hz), 127.92, 127.22, 118.90,
104.73, 81.15, 80.94, 74.18, 73.90, 70.09, 55.15, 54.64. HRMS
(M + H)+: calcd for C2013CH26O4 343.1824, found 343.1810.
on aluminum plates precoated with Merck silica gel 60 F254
,
and spots were detected with a UV lamp (253.7 nm). Column
chromatography was performed on silica gel (Wakogel C-300,
purchased from Wako Pure Chemicals Co., Ltd.) and Kieselgel
60 (Merck Co., Ltd.). Solvents were reagent grade and in many
cases were dried before use.
4-Ald eh yd o-2,3-d i-O-ben zyl-D-er yth r ose Diben zyl Ac-
eta l (5-Bn ). Compound 5-Bn was prepared by oxidation using
a solution of NaIO4 (450 mg, 2.1 mmol) in 5.0 mM aqueous
H2SO4 (4.0 mL) at rt from 4-Bn (1.06 g, 2.0 mmol) in 99% (980
Non la b eled 4,5-Di-O-b en zoyl-2,3-d i-O-d ib en zyl-D-r i-
bose Diben zyl Aceta l (8). Stoich iom etr ic Meth od . To 6′-
Bn (nonlabeled) (247 mg, 0.5 mmol) under an argon atmo-
sphere (1.0 mL) in a mixture of pyridine (1.0 mL)-THF (4.0
mL) was added 1.0 M OsO4 in t-BuOH (0.6 mL) at rt and the
mixture stirred for 1.5 h. The solution of NaHSO3 (230 mg,
2.35 mmol) in H2O (3.8 mL)-pyridine (2.5 mL) was added and
the resulting mixture stirred for 2 h. To the reaction mixture
was added saturated aqueous NaHCO3 (30 mL) followed by
extraction with CHCl3 (50 mL × 3). The extract was washed
with brine (50 mL) and dried (MgSO4) (7′-Bn ). After the
organic layer was evaporated to dryness, the residue was
coevaporated with pyridine twice under an argon atmosphere.
The residue was dissolved in CH2Cl2 (5.0 mL), benzoyl chloride
(0.13 mL, 1.1 mmol) and 4-(dimethylamino)pyridine (DMAP)
(274 mg, 2.25 mmol) were added, and the mixture was stirred
for 1 h at rt. The reaction was quenched with MeOH (1.0 mL),
5% citric acid in H2O (30 mL) was added, and the mixture was
extracted with Et2O (40 mL × 3). The extract was washed with
saturated NaHCO3 solution in H2O (40 mL) and brine (40 mL)
and then dried (MgSO4). After filtration, the solution was
evaporated, and the residue was subjected to silica gel column
chromatography employing hexane-AcOEt to give 8 (nonla-
beled) (357 mg, 97%), 4R/4S ) 92:8. 1H NMR (CDCl3): δ 7.2-
1
mg) yield. H NMR (CDCl3): δ 9.56 (1H, d, J 3,4 ) 0.8 Hz, H4),
7.2-7.4 (20H, m, Ph-H), 4.98 (1H, d, J 1,2 ) 6.6 Hz, H1), 4.5-
4.8 (8H, m, Bn-CH × 8), 4.14 (1H, dd, J 2,3 ) 2.1 Hz, J 3,4 ) 0.8
Hz, H3), 3.98 (1H, dd, J 1,2 ) 6.6 Hz, J 2,3 ) 2.1 Hz, H2). 13C
NMR (CDCl3): δ 201.29, 137.79, 137.72, 137.35, 137.16, 128.38,
128.32, 127.91, 127.87, 127.71, 127.67, 127.63, 101.17, 83.07,
81.72, 73.21, 73.06, 70.40, 69.60. Anal. Calcd for C33H36O6‚0.3
H2O: C, 76.57; H, 6.94. Found: C, 73.84; H, 6.80.
4-Ald eh yd o-2,3-d i-O-ben zyl-D-er yth r ose Dim eth yl Ac-
eta l (5-Me). Compound 5-Me was prepared by oxidation using
9.3 mL of an aqueous solution of NaIO4 (1.05 g, 4.9 mmol) at
rt from 4-Me (1.75 g, 4.7 mmol) in 95% (1.52 g) yield. 1H NMR
(CDCl3): δ 9.55 (1H, d, J 3,4 ) 0.8 Hz, H4), 4.76 (1H, d, Bn-H),
4.69 (1H, d, J ) 12.1 Hz, Bn-H), 4.67 (1H, d, J ) 11.8 Hz,
Bn-CH), 4.62 (1H, d, J ) 11.6 Hz, Bn-H), 4.58 (1H, d, J 1,2
)
6.8 Hz, H1), 4.06 (1H, d, J 3, ) 2.1 Hz, H3), 3.81(1H, dd, J 2,3
2
) 2.1 Hz, J 2,1 ) 6.8 Hz, H2), 3.40 & 3.41 (6H, s, OCH3). 13C
NMR (CDCl3): δ 201.29, 137.79, 137.72, 137.35, 127.16,
128.38, 128.32, 127.91, 127.87, 127.71, 127.67, 127.63, 101.17,
83.07, 81.72, 73.21, 73.06, 70.40, 69.60. Anal. Calcd for
C
20H24O5‚0.7 H2O: C, 67.62; H, 7.15. Found: C, 67.67; H, 6.86.
2,3-Di-O-ben zyl-4,5-d id eh yd r o-4,5-d id eoxy-D-[5-13C]r i-
8.0 (30H, m, Ph-H), 5.88 (1H, m, H4), 5.02 (0.08H, d, J 1,2
)
bose Diben zyl Aceta l (6-Bn ). BuLi (1.6 M) in hexane (1.35
5.5 Hz, H1(4S)), 4.92 (0.92H, d, J 1,2 ) 6.0 Hz, H1(4R)), 4.4-
4.9 (10H, m, H5, H5‘, Bn-CH x 8), 4.18 (0.92H, J 2,3 ) 3.4 Hz,
J 3,4 ) 5.3 Hz, H3(4R)), 4.2 (0.08H, J 2,3 ) 4.1 Hz, J 3,4 ) 4.8 Hz,
H3 (4S)), 3.93 (1H, dd, J 1,2 ) 6.0 Hz, J 2,3 ) 3.4 Hz, H2).
(20) Markiewicw, W. T. J . Chem. Res., Synop. 1979, 24-25.
(21) (a) Zou, R.; Robins, M. J . Can. J . Chem. 1987, 65, 1436-1437.
(b) Robins, M. J .; Wilson, J . S.; Hansske, F. J . Am. Chem. Soc. 1983,
105, 4059-4065.
Ca ta lytic Meth od . To solution of 6′-Bn (nonlabeled) (247
mg, 0.5 mmol) in H2O-acetone (1:8) (9 mL) were added
(22) 50% (w/w) in CHCl3 was produced from Kobayashi Kagaku.
J . Org. Chem, Vol. 67, No. 15, 2002 5147

Kawashima et al.
4-methylmorpholine N-oxide 2-hydroxide (488 mg, 3.6 mmol)
and 1.0 M OsO4 in t-BuOH (86 µL, 0.005 mol equiv) at rt. After
being stirred for 24 h, the mixture was quenched with
saturated aqueous NaHSO3 (5.0 mL) and stirred for 30 min.
Water (40 mL) was added to the reaction mixture, which was
then partitioned between CHCl3 (50 mL × 3) and H2O. The
CHCl3 layer was washed with brine (50 mL) and dried (MgSO4)
(7′-Bn ). After the organic layer was evaporated to dryness, the
residue was treated similarly to the stoichiometric method to
give benzoyl derivative 8 (nonlabeled) (356 mg, 97%) 4R/4S )
93:7: 1H NMR (CDCl3): δ 7.2-8.0 (30H, m, Ph-H), 5.88 (1H,
m, H4), 5.02 (0.07H, d, J 1,2 ) 5.5 Hz, H1(4S)), 4.92 (0.93H, d,
J 1,2 ) 6.0 Hz, H1(4R)), 4.4-4.9 (10H, m, H5, H5′, Bn-CH ×
8), 4.18 (0.93H, J 2,3 ) 3.4 Hz, J 3,4 ) 5.3 Hz, H3(4R)), 4.16
(0.07H, J 2,3 ) 4.1 Hz, J 3,4 ) 4.8 Hz, H3(4S)), 3.93 (1H, dd, J 1,2
) 6.0 Hz, J 2,3 ) 3.4 Hz, H2).
2,3-Di-O-ben zyl-D-[5-13C]r ibose Diben zyl Aceta l (7-Bn ).
Compound 6-Bn (852 mg, 1.7 mmol) in H2O-acetone (1:8) (27
mL) was treated similarly to the catalytic method. After the
CHCl3 layer was evaporated to dryness, the residue was
subjected to silica gel column chromatography employing
hexane-AcOEt to give a mixture of D-ribose derivative 7-Bn
and the corresponding l-lyxo isomer (899 mg, 99% 93:7). The
mixture was subjected to silica gel column chromatography
employing hexane-AcOEt again to give D-ribose derivative
7-Bn (817 mg, 90%). 1H NMR (CDCl3): δ 7.2-7.4 (20H, m,
Ph-H), 4.90 (1H, d, J 1,2 ) 5.7 Hz, H1), 4.81 (1H, d, J ) 11.5
Hz, Bn-CH), 4.76 (1H, d, J ) 11.5 Hz, Bn-CH), 4.72 (1H, d, J
) 11.6 Hz, Bn-CH), 4.70 (1H, d, J ) 11.7 Hz, Bn-CH), 4.65
(1H, d, J ) 11.7 Hz, Bn-CH), 4.58 (1H, d, J ) 11.5 Hz, Bn-
CH), 4.57 (1H, d, J ) 11.6 Hz, Bn-CH), 4.48 (1H, d, J ) 11.5
Hz, Bn-CH), 3.4-4.0 (5H, m, H2, H3, H4, H5, H5′), 3.12 (1H,
t, J ) 4.4 Hz, 4-OH), 2.08 (1H, m, 5-OH). 13C NMR (CDCl3):
δ 137.96, 137.77, 137.16, 128.52, 128.47, 128.42, 128.07,
128.00, 127.90, 127.82, 101.72, 80.71, 79.30, 74.38, 72.92, 71.24
(d, J 4,5 ) 40.1 Hz), 70.55, 70.22, 63.94. Anal. Calcd for
C3213CH36O6: C, 74.97; H, 6.86. Found: C, 74.67; H, 6.95.
4.58 (1H, d, J ) 11.7 Hz, Bn-CH), 4.50 (1H, d, J ) 11.7 Hz,
Bn-CH), 4.28 (1H, m, H4), 4.13 (1H, dd, J
) 4.5 Hz, J 3,4 )
2,3
7.0 Hz, J 3,5C ) 4.5 Hz, H3), 3.87 (1H, d, J 2,3 ) 4.7 Hz, H2),
3.80 (1H, m, J 5′,5-OH ) 3.0 Hz, J 4,5′ ) 3.0 Hz, J 5′,5 ) 12.0 Hz,
J 5′,5C ) 143.8 Hz, H5′), 3.59 (1H, m, J 5,5OH ) 3.6 Hz, J 4,5 ) 3.6
Hz, J 5′,5 )12.1 Hz, J 5,5C ) 142.5 Hz, H5), 3.37 (3H, s, OCH3),
1.95 (1H, b, 5-OH). 13C NMR (CDCl3): δ 137.69, 130.26, 128.71,
127.71, 106.98, 82.19 (J 5,4 ) 29.6 Hz), 80.32, 77.32, 72.52,
72.34, 62.68, 61.72, 55.43. Anal. Calcd for C1913CH24O5: C,
69.83; H, 7.00. Found: C, 69.75; H, 6.97.
Meth yl 2,3,5-Tr i-O-ben zoyl-D-[5-13C]r ibofu r an oside (11).
Meth od A: F r om 7-Bn . To 7-Bn (899 mg, 1.7 mmol) in
MeOH (17 mL) was added 10% Pd-C (170 mg) at rt and the
mixture stirred under hydrogen gas for 36 h. After the filtrate
was evaporated, the residue was solved in dry MeOH (10 mL),
concd H2SO4 (0.05 mL) was added at 0 °C, and the mixture
was stirred for 24 h. The reaction solution was neutralized
with Dowex 1-X2 (OH-), the filtrate was evaporated, and the
residue was coevaporated with dry pyridine (5 mL) three times.
Benzoyl chloride (0.69 mL, 6.0 mmol) in pyridine (20 mL) was
added under an argon atmosphere. After being stirred for 32
h, the reaction was quenched with MeOH (1.0 mL), 5% citric
acid in H2O (40 mL) was added, and the mixture was extracted
with Et2O (40 mL × 3). The extract was washed with a
saturated aqueous NaHCO3 (40 mL) and brine (40 mL) and
then dried (MgSO4). After filtration, the solution was evapo-
rated, and the residue was subjected to silica gel column
chromatography employing hexane-AcOEt to give 11 (748 mg,
92%).
(R-Anomer). 1H NMR (CDCl3): δ 7.28-8.10 (15H, m, Ph-
H), 5.72 (1H, ddd, J 2,3 ) 7.1 Hz, J 3,4 ) 3.5 Hz, J 3,C5 ) 3.8 Hz,
H3), 5.39 (1H, d, J 1,2 ) 4.4 Hz, H1), 5.33 (1H, dd, J 1,2 ) 4.4
Hz, J 2,3 ) 7.1 Hz, H2), 4.74 (1H, ddd, J 4,5′ ) 3.4 Hz, J 5,5′
)
12.0 Hz, J 5′,C5 ) 149.7 Hz, H5′), 4.65 (1H, m, H4), 4.61 (1H,
ddd, J 4,5 ) 4.0 Hz, J 5,5′ ) 12.0 Hz, J 5,C5 ) 148.5 Hz, H5), 3.49
(3H, s, 1-OCH3). 13C NMR (CDCl3): δ 166.15, 165.93, 165.46,
133.34, 133.22, 129.90, 129.80, 129.68, 129.58, 129.47, 129.15,
128.49, 128.43, 128.28, 101.90, 79.39(d, J 4,5 ) 43.9 Hz), 71.76,
70.76, 64.03, 55.72. Anal. Calcd for C2613CH24O8: C, 67.92; H,
5.07. Found: C, 67.89; H, 5.11. (â-Anomer). 1H NMR (CDCl3):
2,3-Di-O-ben zyl-D-[5-13C]r ibose Dim eth yl Aceta l (7-Me).
A solution of 6-Me (64.5 mg, 0.19 mmol) in H2O-acetone
(1:9) (2 mL) was treated similarly to the catalytic method. The
reaction was quenched with a sodium disulfite (Na2S2O5)(57
mg, 0.29 mmol) and stirred for 1 h. Water (20 mL) was added
to the reaction mixture, which was then partitioned between
Et2O (50 mL × 3). The Et2O layer was washed with brine (50
mL) and dried (MgSO4). After filtration, the solution was
evaporated and the residue was subjected to silica gel column
chromatography, using hexane-AcOEt as eluent, to give 7-Me
and the corresponding L-lyxo isomer (69 mg, 96%, 92:8). The
mixture was subjected to silica gel column chromatography
employing hexane-AcOEt again to give D-ribose derivative
δ 7.3-8.1 (15H, m, Ph-H), 5.87 (1H, ddd, J 2,3 ) 4.9 Hz, J 3,4
)
7.0 Hz, J 3,C5 ) 4.5 Hz, H3), 5.68 (1H, d, J 2,3 ) 4.9 Hz, H2),
5.16 (1H, s, H1), 4.3-5.0 (3H, m, H4, H5, H5′), 3.42 (3H, s,
1-OCH3). 13C NMR (CDCl3): δ 166.14, 165.31, 165.19, 133.40,
133.30, 133.05, 129.72, 129.67, 129.18, 128.90, 128.41, 128.29,
128.20, 106.34, 78.94 (d, J 4,5 ) 43.7 Hz), 75.39, 72.38, 64.71,
55.29. Anal. Calcd for C2613CH24O8: C, 67.92; H, 5.07. Found:
C, 67.89; H, 5.11.
Meth od B: F r om 10. To 10 (1.34 g, 3.87 mmol) in dry
MeOH (40 mL) was added 10% Pd-C (160 mg) at rt and the
mixture stirred under hydrogen gas for 44 h. After the filtrate
was evaporated, the residue was coevaporated with dry
pyridine (5 mL) three times, and to it was added benzoyl
chloride (1.53 mL, 12.8 mmol) in pyridine (20 mL) under an
argon atmosphere. After being stirred for 25 h, the reaction
was quenched with MeOH (1.0 mL), and the reaction mixture
was extracted with Et2O (50 mL × 3). The extract was washed
with saturated aqueous NaHCO3 (40 mL) and brine (40 mL)
and then dried (MgSO4). After filtration, the solution was
evaporated, and the residue was subjected to silica gel column
chromatography employing hexane-AcOEt to give 11 (1.8 g,
92%).
1-O-Acetyl-2,3,5-tr i-O-ben zoyl-D-[5-13C]r ibose (12). To
the solution of 11 (747 mg, 1.6 mmol) and acetic anhydride
(1.0 mL) in acetic acid (4.3 mL) was added concd H2SO4 (0.23
mL) at 0 °C and the mixture stirred for 3 h. Ice-H2O (30 mL)
was added to the reaction mixture, which was extracted with
Et2O (50 mL × 3) and washed with H2O (50 mL), a saturated
aqueous NaHCO3 (50 mL × 2), and brine (50 mL), and then
the Et2O layer was dried (MgSO4). After filtration, the extract
was evaporated, and the residue was subjected to silica gel
column chromatography, using hexane-AcOEt as eluent, to
1
7-Me (62 mg, 86%). H NMR (CDCl3): δ 7.38-7.28 (10H, m,
Ph-H), 4.80 (1H, d, J ) 11.6 Hz, Bn-H), 4.74 (1H, d, J ) 11.6
Hz, Bn-H), 4.67 (1H, d, J ) 11.4 Hz, Bn-CH), 4.54 (1H, d, J )
11.4 Hz, Bn-CH), 4.50 (1H, d, J 1,2 )5.7 Hz, H1), 3.92-3.50
(1H, m, H2, H3, H4, H5, H5′), 3.47 (6H, s, OCH3), 3.19 (1H, J
) 2.8 Hz, 4-OH), 2.19 (1H, b, 5-OH). 13C NMR (CDCl3): δ
138.00, 128.24, 127.86, 124.85, 108.75, 105.20, 79.86, 79.46,
74.09, 72.96, 71.31(d, J 4,5 ) 40.1 Hz), 70.92, 63.86, 63.72. Anal.
calcd for C2013CH28O6‚0.2H2O: C, 66.45; H, 7.51. Found: C,
66.52; H, 7.49.
Meth yl 2,3-Di-O-ben zyl-D-[5-13C]r ibofu r a n osid e (10). To
7-Me (1.18 g, 3.13 mmol) in 2% H2O-CH3CN (30 mL) was
added LiBF4 (382 mg, 4.07 mmol) at rt. After being stirred for
20 h, the reaction mixture was quenched with the saturated
NaHCO3 solution in H2O (20 mL) and then partitioned
between CHCl3 (50 mL × 3). The CHCl3 layer was washed
with brine (50 mL) and dried (MgSO4). After filtration, the
solution was evaporated, and the residue was subjected to
silica gel column chromatography, using hexane-AcOEt as
eluent, to give 10 (1.06 g, 98%). (â-Anomer). 1H NMR
(CDCl3): δ 7.3-7.4 (10H, m, Ph-H), 4.89 (1H, s, H1), 4.67 (1H,
d, J ) 12.0 Hz, Bn-CH), 4.63 (1H, d, J ) 12.0 Hz, Bn-CH),
5148 J . Org. Chem., Vol. 67, No. 15, 2002

Synthesis of [5′-13C]Ribonucleosides
give 12 (775 mg, 98%). The resulting solid was crystallized
from CHCl3-hexane to give the â-anomer of 12. Moreover, the
filtrate was concentrated to dryness and again was crystallized
from hexane for anomerization to give the crystal â-anomer
of 12. mp: 130-131 °C. (â-Anomer). 1H NMR (CDCl3): δ 7.3-
8.1 (15H, m, Ph-H), 6.43 (1H, s, H1), 5.91 (1H, ddd, J 2,3 ) 4.9
Hz, J 3,4 ) 7.1 Hz, J 3,C5 ) 4.5 Hz, H3), 5.79 (1H, d, J 2,3 ) 4.9
2′,3′,5′-Tr i-O-ben zoyl[5′-13C]r ibosylth ym in e (13T). Com-
pound 13T (280 mg, 98%) was prepared from 2,4-bis(trimeth-
ylsilyloxy)-5-methylpyrimidine in CHCl3 (50% w/w) (0.3 mL)
and the â-anomer of 12 (252 mg, 0.5 mmol). 1H NMR (CDCl3):
δ 7.3-8.2 (16H, m, H3, Ph-H), 7.16 (1H, d, J 5Me,6 ) 1.2 Hz,
H6), 6.43 (1H, d, J 1′,2′ ) 6.4 Hz, H1′), 5.91(1H, m, H3′), 5.75
(1H, dd, J 1‘,2′ ) 6.4 Hz, J 2′,3′ ) 6.2 Hz, H2′), 4.89 (1H, m, H5′′),
4.70 (1H, m, H4′), 4.65 (1H, ddd, J 4′,5′ ) 3.4 Hz, J 5′,5′′ ) 12.3
Hz, J 5′,C5‘ ) 148.3 Hz, H5′), 1.60 (3H, d, J 5Me,6 ) 1.2 Hz, 5-CH3).
13C NMR (CDCl3): δ 165.98, 165.40, 164.32, 163.07, 150.17,
134.78, 133.79, 133.73, 129.92, 129.83, 129.63, 129.20, 128.87,
128.56, 128.54, 128.34, 112.19, 86.87, 80.61 (d, J 4′,5′ ) 42.8 Hz),
73.34, 71.42, 63.91, 12.08. HRMS (M + H)+: calcd for
C3013CH26N2O9 572.1750, found 572.1744. Anal. Calcd for
C3013CH26N2O9‚0.2 H2O: C, 64.74; H,4.63; N,4.87. Found: C,
64.60; H, 4.57; N, 5.19.
Hz, H2), 4.79 (1H, m, H4), 4.77 (1H, ddd, J 4,5′ ) 3.8 Hz, J 5,5′
12.1 Hz, J 5′,C5 ) 149.7 Hz, H5′), 4.51 (1H, ddd, J 4,5 ) 4.6 Hz,
J 5,5′ ) 12.1 Hz, J 5,C5 ) 148.2 Hz, H5), 2.01(3H, s, COCH3). 13
)
C
NMR (CDCl3): δ 169.07, 165.98, 165.36, 165.02, 133.67,
135.56, 133.26, 129.84, 129.76, 129.58, 128.82, 128.66, 128.54,
128.41, 98.40, 79.66 (d, J 4,5 ) 43.7 Hz), 74.99, 71.37, 63.72,
20.89. Anal. Calcd for C2713CH24O9: C, 66.53; H, 4.79. Found:
C, 66.36; H, 4.81.
P r oced u r e for Cou p lin g Rea ction of Com p ou n d 12
w ith a P er silyla ted Nu cleoba se. The coupling reaction of
compound 12 with a persilylated nucleobase (persilylated N6-
benzoyladenine, N2-acetyl-O6-diphenylcarbamoylguanine, N4-
benzoylcytosine, thymine, and uracil) was performed according
to the method of Vorbru¨gen19 by use of trimethylsilyl trifluo-
2′,3′,5′-Tr i-O-ben zoyl[5-13C]u r idin e (13U). Compound 13U
(87 mg, 78%) was prepared from persilylated uracil (0.26
1
mmol) and the â-anomer of 12 (101 mg, 0.2 mmol). H NMR
(CDCl3): δ 7.3-8.2 (17H, m, H3, H6, Ph-H), 6.31 (1H, d, J 1′,2′
) 5.6 Hz, H1′), 5.88 (1H, m, H3′), 5.75 (1H, dd, J 1′,2′ ) 5.6 Hz,
J 2′,3′ ) 5.8 Hz, H2′), 5.61 (1H, d, J 5,6 ) 8.1 Hz, J 3,5 ) 2.3 Hz,
romethanesulfonate (TMSOTf) as Lewis acid to give 13ABz
,
DP C
13
G
, 13CBz, 13U, and 13T.
Ac
H5), 4.84 (1H, ddd, J 4′,5′′ ) 3.0 Hz, J 5′,5′′ ) 12.4 Hz, J 5′,C5′
)
N,6O2‘,O3′,O5‘-Tetr aben zoyl[5′-13C]aden osin e (13ABz). Com-
150.5 Hz, H5′′), 4.72 (1H, m, H4′), 4.67 (1H, ddd, J 4′,5′ ) 3.9
Hz, J 5′,5′′ ) 12.4 Hz, J 5′,C5′ ) 149.0 Hz, H5′). 13C NMR (CDCl3):
δ 166.02, 165.31, 165.26, 162.78, 150.08, 139.58, 133.78,
133.72, 133.62, 129.88, 129.80, 129.61, 129.19, 128.73, 128.51,
128.32, 103.39, 88.08, 80.48 (d, J 4′,5′ ) 43.1 Hz), 73.71, 71.11,
63.71. Anal. Calcd for C2913CH24N2O9‚0.2H2O: C, 64.21; H,
4.38; N, 4.99. Found: C, 64.17; H, 4.37; N, 5.32.
pound 13ABz (544 mg, 80%) was prepared from persilylated
N6-benzoyladenine (1.30 mmol) and the â-anomer of 12 (505
1
mg, 1.0 mmol). H NMR (CDCl3): δ 8.93 (1H, bs, 6-NH), 8.71
(1H, s, H8), 8.17 (1H, s, H2), 7.3-8.1 (20H, m, Ph-H), 6.50
(1H, d, J 1′,2′ ) 5.3 Hz, H1′), 6.43 (1H, dd, J 1′,2′′ ) J 2′,3′ ) 5.3 Hz,
H2′), 6.27 (1H, m, H3′), 4.93 (1H, ddd, J 4′,5′′ ) 3.2 Hz, J 5′,5′′
)
12.3 Hz, J 5′′,C5′ ) 145.0 Hz, H5′′), 4.85 (1H, m, H4′), 4.71(1H,
Syn th esis of 14ABz, 14AcGDP C, 14CBz, and 14T. Compounds
ddd, J 4′,5′) 4.3 Hz, J 5′,5′′ ) 12.3 Hz, J 5′,C5′ ) 149.2 Hz, H5′). 13
C
14ABz, 14AcGDP C, 14CBz, and 14T were prepared from 13ABz
,
NMR (CDCl3): δ 166.12, 165.32, 165.13, 164.41, 153.05,
151.69, 149.71, 141.57, 133.83, 133.76, 133.48, 132.81, 129.83,
129.74, 129.29, 128.88, 128.70, 128.62, 128.57, 128.53, 128.34,
127.82, 123.53, 87.01, 80.95 (d, J 4′,5′ ) 43.0 Hz), 73.91, 71.50,
63.53. HRMS (M + H)+: calcd for C3713CH29N5O8 685.2128,
found 68.2101. Anal. Calcd for C3713CH29N5O8‚0.5H2O: C,
65.79; H, 4.32; N, 10.10. Found: C, 65.84; H, 4.25; N, 10.15.
DP C
13
G
, 13CBz, and 13T according to the method of Mark-
Ac
iewicw20 after debenzoylation.
N6-Bz-3′,5′-O-TIP DS-[5′-13C]a d en osin e (14ABz) was ob-
tained from 13ABz (342 mg, 0.5 mmol) in 74% yield (228 mg).
1H NMR (CDCl3): δ 9.00 (1H, bs, 6NH), 8.75 (1H, s, H8), 8.14
(1H, s, H2), 7.4-8.1 (5H, m, Ph-H), 6.04 (1H, d, J 1′,2′ ) 1.2 Hz,
H1′), 5.13 (1H, m, H3′), 4.64 (1H, m, H2′), 4.14 (1H, ddd, J 4′,5′′
) 4.8 Hz, J 5′,5′′ ) 12.5 Hz, J 5′,C5′ ) 146.2 Hz, H5′′), 3.72 (1H,
N2-Acetyl-2′,3′,5′-tr i-O-ben zoyl-6-O-diph en ylcar bam oyl-
[5-13C]gu a n osin e (13AcGDP C). 13AcGDP C (658 mg, 79%) was
prepared from persilylated N2-acetyl-6-O-diphenylcarbam-
oylguanine20 (1.3 mmol) and the â-anomer of 12 (505 mg, 1.0
m, H4′), 3.67 (1H, ddd, J 4′,5′ ) 3.2 Hz, J 5′,5′′ ) 12.5 Hz, J 5′,C5′
)
i
142.2 Hz, H5′), 3.21 (1H, bs, 2′-OH), 0.9-1.3 (28H, m, Pr x
4). 13C NMR (CDCl3): δ 164.72, 152.74, 51.06, 149.75, 142.04,
133.73, 132.80, 128.87, 127.95, 123.72, 89.88, 82.28 (d, J 4′,5′
1
mmol). H NMR (CDCl3): δ 8.08 (1H, bs, 2-NH), 8.06 (1H, s,
)
H8), 7.20-8.03 (25H, m, Ph-H), 6.2-6.4 (3H, m, H1′, H2′, H3′),
4.91 (1H, ddd, J 4′,5′′ ) 3.4 Hz, J 5′,5′′ ) 12.3 Hz, J 5′′,C5′) 149.7
43.8 Hz), 75.12, 70.79, 61.65, 17.48, 17.40, 17.33, 17.15, 17.03,
16.96, 13.33, 13.09, 12.81, 12.66. HRMS (M + H)+: calcd for
C2813CH43N5O6Si2 615.2684, found 615.2860.
Hz, H5′′), 4.85 (1H, m, H4′), 4.71 (1H, ddd, J 4′,5′) 5.1 Hz, J 5′,5′′
)
12.3 Hz, J 5′,C5′ ) 149.8 Hz, H5′), 2.46 (3H, s, COCH3). 13C NMR
(CDCl3): δ 169.88, 166.16, 165.20, 165.08, 156.39, 154.30,
152.27, 150.15, 142.35, 141.68, 133.82, 133.66, 133.40, 139.79,
129.60, 129.17, 128.69, 128.54, 128.51, 128.32, 127.07 (br),
121.30, 87.46, 80.56 (d, J 4′,5′ ) 43.4 Hz), 74.18, 71.45, 63.62,
25.09. HRMS (M + H)+: calcd for C4513CH36N6O10 834.2605,
found 834.2570. Anal. Calcd for C4513CH36N6O10‚0.4H2O: C,
65.70; H, 4.41; N, 9.99. Found: C, 65.55; H, 4.37; N, 10.03.
N2-Acet yl-6-O-d ip h en ylca r b a m oyl-3′,5′-O-TIP DS-[5′-
13C]gu a n osin e (14AcGDP C) was obtained from 13AcGDP C (416
mg, 0.5 mmol) in 45% yield (171 mg). 1H NMR (CDCl3): δ 8.12
(1H, s, H8), 7.96 (1H, bs, 2-NH), 7.2-7.5 (10H, m, Ph-H), 5.98
(1H, d, J 1′,2′ ) 1.2 Hz, H1′), 4.68 (1H, m, H3′), 4.46 (1H, m,
H2′), 4.14 (1H, ddd, J 4′,5′′ ) 4.1 Hz, J 5′,5′′ ) 12.9 Hz, J 5′′,C5′
)
146.6 Hz, H5′′), 3.85 (1H, m, H4′), 3.71 (1H, ddd, J 4′,5′ ) 3.0
Hz, J 5′,5′′ ) 12.8 Hz, J 5′,C5′ ) 141.6 Hz, H5′), 3.17 (1H, bs, 2′-
OH), 2.54 (3H, s, COCH3), 0.9-1.2 (28H, m, iPr × 4). 13C NMR
(CDCl3): δ 170.50, 156.22, 154.02, 152.11, 150.29, 141.92,
141.70, 129.17, 126.89 (br), 121.32, 89.32, 82.22 (d, J 4′,5′ ) 43.5
Hz), 74.86, 70.34, 61.33, 25.14, 17.42, 17.34, 17.28, 17.19,
17.10, 17.01, 16.95, 16.91, 13.31, 13., 12.85, 12.58. HRMS (M
+ H)+: calcd for C3613CH51N6O8Si2 764.3341, found 764.3366.
Tetr a-N4,O2′,O3′,O5′-ben zoyl[5′-13C]cytidin e (13CBz). Com-
pound 13CBz (315 mg, 96%) (mp 211-212 °C) was prepared
from persilylated N4-benzoylcytosine (0.65 mmol) and the
1
â-anomer of 12 (252 mg, 0.5 mmol). H NMR (CDCl3): δ 8.72
(1H, bs, 4-NH), 7.3-8.2 (22H, m, H5, H6, Ph-H), 6.50 (1H, d,
J 1′,2′ ) 4.6 Hz, H1′), 5.93 (1H, ddd, J 2′,3′ ) 5.6 Hz, J 3′,4′ ) 3.4
Hz, J 3′,C5′ ) 5.5 Hz, H3′), 5.86 (1H, dd, J 1′,2′ ) 4.6 Hz, J 2′,3′
)
N4-Ben zoyl-3′,5′-O-TIP DS-[5′-13C]cytid in e (14CBz) was
obtained from 13CBz (330 mg, 0.5 mmol) in 78% yield (231 mg).
1H NMR (CDCl3): δ 8.70 (1H, bs, 4NH), 8.23 (1H, d, J 5,6 ) 7.5
Hz, H6), 7.5-8.0 (6H, m, H5, Ph-H), 5.85 (1H, s, H1′), 4.68
(1H, m, H3′), 4.29 (1H, dd, J 5′,5′′ ) 13.4 Hz, J 5′′,C5′ ) 148.2 Hz,
H5′′), 4.26 (1H, d, J 2′,3′ ) 4.7 Hz, H2′), 3.83-4.23 (2H, m, H4′,
H5′), 2.97 (1H, bs, 2′-OH), 0.9-1.2 (28H, m, iPr × 4). 13C NMR
(CDCl3): δ 166.75, 162.56, 154.72, 144.46, 133.07, 128.92,
127.60, 96.35, 91.64, 81.94 (d, J 4′,5′ ) 43.1 Hz), 75.09, 68.45,
59.94, 17.39, 17.34, 17.23, 16.91, 16.83, 18.75, 13.32, 12.87,
5.6 Hz, H2′), 4.86 (1H, ddd, J 4′,5′′ ) 2.8 Hz, J 5′,5′′ ) 12.5 Hz,
J 5′′,C5′ ) 150.3 Hz, H5′′), 4.85 (1H, m, H4′), 4.71 (1H, ddd, J 4′,5′
) 4.0 Hz, J 5′,5′′ ) 12.5 Hz, J 5′,C5′ ) 148.9 Hz, H5′). 13C NMR-
(CDCl3): δ 166.03, 165.15, 165.07, 162.59, 154.50, 144.26,
133.51, 133.23, 133.06, 129.85, 129.72, 129.58, 129.17, 128.85,
128.63, 128.55, 128.35, 127.61, 97.43, 89.44, 80.65 (d, J 4′,5′
43.2 Hz), 74.72, 70.94, 63.57. HRMS (M + H)+: calcd for C36
CH29N3O9 661.2016, found 661.1977. Anal. Calcd for C36
)
13
-
-
13
CH29N3O9: C, 67.26; H, 4.42; N, 6.36. Found: C, 67.04; H, 4.39;
N, 6.61.
J . Org. Chem, Vol. 67, No. 15, 2002 5149

Kawashima et al.
12.40. HRMS (M + H)+: calcd for C2713CH43N3O7Si2 591.2751,
found 591.2727.
deoxygenation of 15ABz, 15AcGDP C, 15CBz, and 15T was
performed according to the method of Robins et al.21
3′,5′-O-TIP DS-[5′-13C]r ibosylth ym in e (14T) was obtained
N6-Benzoyl-2′-deoxy-3′,5′-O-TIPDS-[5′-13C]adenosine (16ABz)
was obtained from 15ABz (150 mg, 0.2 mmol) in 85% yield (101
mg). 1H NMR (CDCl3): δ 9.02(1H, bs, 6-NH), 8.78 (1H, s, H8),
1
from 13T (278 mg, 0.5 mmol) in 72% yield (175 mg). H NMR
(CDCl3): δ 7.94 (1H, bs, H3), 7.35 (1H, d, J 5Me,6 ) 0.9 Hz, H6),
5.70 (1H, d, J 1′,2′ ) 0.9 Hz, H1′), 4.43 (1H, m, H3′), 4.19 (1H,
8.22 (1H, s, H2), 7.5-8.1 (5H, m, Ph-H), 6.36 (1H, dd, J 1′,2′
)
m, H2′), 4.17 (1H, dd, J 4′,5′′ ) 2.8 Hz, J 5′,5′′ ) 13.0 Hz, J 5′′,C5′
)
2.5 Hz, J 1′,2′′ ) 7.5 Hz, H1′), 4.99 (1H, m, H3′), 4.06 (2H, m,
H5′, H5′′), 3.92 (1H, m, H4′), 2.79 (1H, ddd, J 1′,2′ ) 2.5 Hz,
J 2′,2′′ ) 13.4 Hz, J 2′,3′ ) 7.4 Hz, H2′), 2.69 (1H, ddd, J 1′,2′′ ) 7.5
Hz, J 2‘,2′′ ) 13.4 Hz, J 2′′,3′ ) 9.0 Hz, H2′′), 0.9-1.3 (28H, m, iPr
x 4). 13C NMR (CDCl3): δ 164.60, 152.51, 150.87, 149.51,
141.49, 133.678, 132.68, 127.78, 127.82, 123.60, 85.26 (d, J 4′,5′
) 43.6 Hz), 83.39, 69.88, 61.74, 39.94, 17.45, 17.35, 17.29,
16.99, 16.93, 16.85, 13.32, 13.06, 12.,82, 12.49. HRMS (M +
H)+: calcd for C2813CH43N5O5Si2 599.2915, found 599.2856.
147.7 Hz, H5′′), 4.06 (1H, m, H4′), 4.01 (1H, dd, J 4′,5′ ) 3.0 Hz,
J 5′,5′′ ) 13.0 Hz, J 5′,C5′ ) 140.0 Hz, H5′), 3.00 (1H, bs, 2′OH),
1.91 (3H, d, J 5Me,6 ) 0.9 Hz, 5-CH3), 0.9-1.2 (28H, m, iPr × 4).
13C NMR (CDCl3): δ 164.13, 150.30, 135.54, 110.53, 91.13,
81.79 (d, J 4′,5′ ) 43.0 Hz), 74.95, 60.16, 17.38, 18.31, 17.20,
17.02, 16.93, 16.78, 13.38, 12.90, 12.68, 12.55, 12.42. HRMS
(M + H)+: calcd for C2113CH40N2O7Si2 502.2486, found 502.2509.
Syn th esis of 15ABz, 15AcGDP C, 15CBz, a n d 15T. Com -
p ou n d s 15ABz, 15AcGDP C, 15CBz, and 15T were prepared from
14ABz, 14AcGDP C, 14CBz, and 14T according to the method of
Robins.21
N2-Acetyl-2′-d eoxy-6-O-d ip h en ylca r ba m oyl-3′,5′-O-TIP -
DS-[5′-13C]gu a n osin e (16AcGDP C). Compound 15AcGDP C (343
mg, 0.38 mmol) was treated similarly to 16ABz to give
DP C
16
G
(255 mg, 90%). 1H NMR (CDCl3): δ 8.16 (1H, s, H8),
N6-Ben zoyl-2′-O-p h en oxyt h ioca r b on yl-3′,5′-O-TIP DS-
[5′-13C]a d en osin e (15ABz) was obtained from 14ABz (220 mg,
0.36 mmol) in 68% yield (184 mg). 1H NMR (CDCl3): δ 8.97
(1H, bs, 6-NH), 8.77 (1H, s, H8), 8.18 (1H, s, H2), 7.1-8.1 (10H,
m, Ph-H), 6.40 (1H, dd, J 1′,2′ ) 0.9 Hz, J 2′,3′ ) 5.3 Hz, H2′),
6.23 (1H, d, J 1′,2′ ) 0.9 Hz, H1′), 5.37 (1H, m, H3′), 4.19 (1H,
ddd, J 4′,5′′ ) 2.7 Hz, J 5′,5′′ ) 12.9 Hz, J 5′,C5′ ) 147.4 Hz, H5′′),
4.16 (1H, m, H4′), 4.08 (1H, ddd, J 4′,5′ ) 2.5 Hz, J 5′,5′′ ) 12.9
Hz, J 5′,C5′ ) 140.3 Hz, H5′), 0.9-1.3 (28H, m, iPr × 4). 13C NMR
(CDCl3): δ 193.88, 164.66, 153.28, 152.72, 151.00, 149.73,
141.97, 133.55, 132.70, 129.54, 128.75, 126.71, 123.57, 121.62,
87.41, 83.80, 82.14 (d, J 4′,5′ ) 43.4 Hz), 69.28, 60.24, 17.35,
17.29, 17.23, 17.07, 16.99, 16.89, 13.20, 12.91, 12.77, 12.75.
HRMS (M + H)+: calcd for C3513CH47N5O7SSi2 751.2847, found
751.2784.
Ac
7.90 (1H, bs, 2-NH), 7.2-7.5 (10H, m, Ph-H), 6.28 (1H, dd,
J 1′,2′ ) 3.3 Hz, J 1′,2′′ ) 6.64 Hz, H1′), 4.72 (1H, m, H3′), 4.04
(2H, m, H5′, H5′′), 3.88 (1H, m, H4′), 2.65 (2H, m, H2′, H2′′),
i
2.55 (3H, s, COCH3), 0.9-1.2 (28H, m, Pr × 4). 13C NMR
(CDCl3): δ 170.72, 156.12, 154.00, 152.02, 150.33, 141.84,
141.72, 129.14, 126.94 (br), 121.22, 85.20 (d, J 4′,5′ ) 43.1 Hz),
83.07, 69.53, 61.51, 39.89, 25.07, 17.45, 17.35, 17.29, 17.14,
16.99, 16.94, 16.85, 13.37, 13.05, 12.91, 12.49. HRMS (M +
H)+: calcd for C3613CH50N6O7Si2 748.3391, found 748.3441.
N 4-Be n zoyl-2′-d e oxy-3′,5′-O-TIP DS-[5′-13C]cyt id in e
(16CBz). Compound 15CBz (200 mg, 0.28 mmol) was treated
similarly to 16ABz to give 16CBz (120 mg, 76%). 1H NMR
(CDCl3): δ 8.65 (1H, bs, 4-NH), 8.31 (1H, d, J 5,6 ) 7.4 Hz, H6),
7.4-8.0 (6H, m, H5, Ph-H), 6.10 (2H, d, J 1′,2′′ ) 6.3 Hz, H1′),
3.7-4.5 (4H, m, H3′, H4′, H5′, H5′′), 2.61 (1H, ddd, J 1′,2′′ ) 6.3
Hz, J 2′,2′′ ) 13.22 Hz, J 2′′,3′ ) 10.9 Hz, H2′′), 2.38 (1H, dd, J 2′,2′′
N2-Acet yl-6-O-d ip h en ylca r b a m oyl-2′-O-p h en oxyt h io-
ca r bon yl-3′,5′-O-TIP DS-[5′-13C]gu a n osin e (15AcGDP C) was
DP C
i
) 13.2 Hz, J 2′,3′ ) 7.4 Hz, H2′), 0.9-1.2 (28H, m, Pr x 4). 13C
obtained from 14
G
(502 mg, 0.66 mmol) in 68% yield (403
Ac
mg). 1H NMR (CDCl3): δ 8.18 (1H, s, H8), 7.90 (1H, bs, 2-NH),
7.2-7.5 (15H, m, Ph-H), 6.24 (1H, dd, J 1′,2′ ) 1.2 Hz, J 2′,3′
5.2 Hz, H2′), 6.20 (1H, d, J 1′,2′ ) 1.2 Hz, H1′), 4.87 (1H, m,
NMR (CDCl3): δ 166.64, 162.30, 154.66, 144.34, 133.00,
128.88, 128.53, 96.04, 85.60, 85.20 (d, J 4′,5′ ) 43.1 Hz), 66.33,
59.69, 39.61, 17.41, 17.36, 17.24, 16.93, 16.87, 16.75, 13.32,
12.95, 12.88, 12.33. HRMS (M + H)+: calcd for C2713CH43N3O6-
Si2 575.2802, found 575.2781.
)
H3′), 4.22 (1H, ddd, J 4′,5′′ ) 2.5 Hz, J 5′,5′′ ) 12.9 Hz, J 5′′,C5′
)
147.9 Hz, H5′′), 4.17 (1H, m, H4′), 4.08 (1H, ddd, J 4′,5′ ) 2.5
Hz, J 5′,5′′ ) 12.9 Hz, J 5′,C5′ ) 140.0 Hz, H5′), 2.58 (3H, s,
3′,5′-O -TIP DS-[5′-13C]th ym id in e (16T). Compound 15T
(165 mg, 0.27 mmol) was treated similarly to 16ABz to give
16T (124 mg, 98%). 1H NMR (CDCl3): δ 8.30 (1H, bs, H3),
7.41 (1H, d, J 5Me,6 ) 1.2 Hz, H6), 6.07 (1H, dd, J 1′,2′ ) 2.3 Hz,
COCH3), 0.9-1.2 (28H, m, iPr × 4). 13C NMR (CDCl3):
δ
193.74, 170.96, 156.35, 153.82, 153.31, 152.33, 150.16, 141.64,
141.55, 129.59, 129.14, 128.90, 128.40, 128.33, 126.90, 126.76
(br), 121.57, 121.11, 86.90, 83.38, 82.40 (d, J 4′,5′ ) 43.1 Hz),
69.04, 60.21, 25.20, 17.37, 17.29, 17.22, 17.01, 16.89, 13.32,
12.90, 12.76. HRMS (M + H)+: calcd for C4313CH54N6O9SSi2
900.3323, found 900.3271.
J 1′,2′′ ) 7.4 Hz, H1′), 4.50 (1H, m, H3′), 4.11 (1H, ddd, J 4′,5′′
)
2.5 Hz, J 5′,5′′ ) 13.1 Hz, J 5′′,C5′ ) 147.2 Hz, H5′′), 4.02 (1H, ddd,
J 4′,5′ ) 3.0 Hz, J 5′,5′′ ) 13.1 Hz, J 5′,C5′ ) 139.5 Hz, H5′), 3.75
(1H, m, H4′), 2.49 (1H, ddd, J 1′,2′′ ) 7.4 Hz, J 2′,2′′ ) 13.5 Hz,
J 2′′,3′ ) 9.7 Hz, H2′′), 2.38 (1H, ddd, J 1′,2′ ) 2.3 Hz, J 2‘,2′′ ) 13.5
Hz, J 2′,3′ ) 7.5 Hz, H2′), 1.93 (3H, d, J 5Me,6 ) 1.2 Hz, 5-CH3),
0.9-1.2 (28H, m, iPr x 4). 13C NMR (CDCl3): δ 164.03, 150.24,
135.13, 110.52, 84.89 (d, J 4′,5′ ) 43.3 Hz), 83.73, 67.52, 60.14,
39.76, 17.42, 14.37, 17.29, 17.25, 17.06, 16.96, 16.81, 13.44,
12.97, 12.73, 12.60, 12.42. HRMS (M + H)+: calcd for
C2113CH40N2O6Si2 486.2537, found 486.2498.
N4-Ben zoyl-2′-O-p h en oxyt h ioca r b on yl-3′,5′-O-TIP DS-
[5′-13C]cytid in e (15CBz) was obtained from 14CBz (267 mg,
0.45 mmol) in 86% yield (284 mg). 1H NMR (CDCl3): δ 8.66
(1H, bs, 4-NH), 8.27 (1 H, d, J 5,6 ) 7.5 Hz, H6), 7.1-8.0 (11 H,
m, H5, Ph-H), 6.09 (2H, m, H1′, H2′), 3.8-4.6 (4 H, m, H3′,
i
H4′, H5′, H5′′), 0.9-1.2 (28 H, m, Pr × 4). 13C NMR (CDCl3):
δ 193.42, 167.10, 162.72, 153.42, 144.02, 133.11, 129.40,
128.93, 127.57, 126.48, 121.75, 96.61, 89.13, 83.52, 82.32 (d,
J 4‘,5′ ) 42.7 Hz), 67.90, 59.34, 17.37, 17.33, 17.21, 17.19, 16.89,
16.84, 13.26, 12.93, 12.81, 12.73. HRMS (M + H)+: calcd for
C3413CH47N3O8SSi2 727.2734, found 727.2681.
N6-Ben zoyl-2′-d eoxy[5′-13C]a d en osin e (17ABz). To 16ABz
(101 mg, 0.17 mmol) in THF (20 mL) was added tetraethyl-
ammonium fluoride (Et4NF)‚2H2O (703 mg, 3.8 mmol) at rt
and the mixture stirred for 4 h. MeOH (20 mL) and silica gel
(10 g) were added to the reaction mixture, and then solvent
was slowly evaporated to dryness. The slurry was subjected
to flash column chromatography employing a CH2Cl2-MeOH
2′-O-P h e n oxyt h ioca r b on yl-3′,5′-O-TIP DS-[5′-13C]r i-
bosylth ym in e (15T) was obtained from 14T (300 mg, 0.6
mmol) in 87% yield (333 mg). 1H NMR (CDCl3): δ 8.41(1H,
bs, H3), 7.35 (6H, m, H6, Ph-H), 6.10 (1H, d, J 2′,3′ ) 5.1 Hz,
H2′), 5.92 (1H, s, H1′), 4.60 (1H, m, H3′), 3.8-4.5 (3H, m, H4′,
1
system to give 17ABz (59.2 mg, 98%). H NMR (MeOH-d4): δ
8.70 (1H, s, H8), 8.65 (1H, s, H2), 7.5-8.1 (5H, m, Ph-H), 6.57
(1H, dd, J 1′,2′ ) 6.1 Hz, J 1′,2′′ ) 6.2 Hz, H1′), 4.61 (1H, m, H3′),
4.07 (1H, m, H4′), 3.84 (1H, ddd, J 4′,5′′ ) 3.3 Hz, J 5′,5′′ ) 12.01
Hz, J 5′′,C5‘ ) 142.2 Hz, H5′), 3.75 (1H, ddd, J 4′,5′ ) 3.8 Hz, J 5′,5′′
) 12.0 Hz, J 5′,C5′ ) 140.9 Hz, H5′), 2.86 (1H, ddd, J 1′,2′ ) 6.1
i
H5′, H5′′), 1.93 (3H, s, 5-CH3), 0.9-1.2 (28H, m, Pr x 4). 13C
NMR (CDCl3): δ 193.76, 163.80, 153.41, 149.72, 135.15,
129.49, 126.60, 121.74, 111.02, 88.55, 83.80, 82.00 (d, J 4′,5′
)
43.3 Hz), 68.37, 59.50, 17.37, 17.32, 17.22, 16.99, 16.897, 13.36,
12.88, 12.79, 12.69, 12.55. HRMS (M + H)+: calcd for C28
-
Hz, J 2′,2′′ ) 13.5 Hz, J 2′,3′ ) 7.2 Hz, H2′), 2.69 (1H, ddd, J 1′,2′′
)
13CH44N2O8SSi2 638.2469, found 638.2435.
6.2 Hz, J 2′,2′′ ) 13.5 Hz, J 2′′,3′ ) 3.4 Hz, H2′′). 13C NMR (MeOH-
d4): δ 168.06, 152.89, 151.16, 144.51, 134.93, 133.88, 129.73,
Syn th esis of 16ABz, 16AcGDP C, 16CBz, a n d 16T. Reductive
5150 J . Org. Chem., Vol. 67, No. 15, 2002

Synthesis of [5′-13C]Ribonucleosides
129.41, 125.44, 89.69 (d, J 4′,5′ ) 41.5 Hz), 86.69, 72.66, 63.30,
41.47. HRMS (M + H)+: calcd for C1613CH17N5O4 357.1392,
found 357.1403.
[5′-13C]Th ym id in e (17T). Compound 16T (47 mg, 0.1
mmol) was treated similarly to 17ABz to give 17T (22.8 mg,
92%). 1H NMR (MeOH-d4): δ 7.81 (1H, d, J 5Me,6 ) 1.2 Hz, H6),
6.27 (1H, d, J 1′,2′ ) J 1′,2′′ ) 6.7 Hz, H1′), 4.39 (1H, m, H3′), 3.91
(1H, m, H4′), 3.79 (1H, ddd, J 4′,5′′ ) 3.2 Hz, J 5′,5′′ ) 12.1 Hz,
N2-Acetyl-2′-d eoxy-6-O-d ip h en ylca r ba m oyl[5′-13C]gu a -
DP C
n osin e (17
G
). Compound 16AcGDP C (222 mg, 0.30 mmol)
Ac
was treated similarly to 17ABz to give 17AcGDP C (134.3 mg,
89%) as a foam. 1H NMR (MeOH-d4): δ 8.58 (1H, s, H8), 7.2-
7.5 (10H, m, Ph-H), 6.51 (1H, dd, J 1′,2′ ) 6.4 Hz, J 1′,2′′ ) 6.5
Hz, H1′), 4.64 (1H, m, H3′), 3.5-4.0 (3H, m, H4′, H5′, H5′),
2.82 (1H, ddd, J 1′,2′ ) 6.4 Hz, J 2′,2′′ ) 13.62 Hz, J 2′,3′ ) 6.4 Hz,
H2′), 2.47 (1H, ddd, J 1′,2′′ ) 6.5 Hz, J 2′,2′′ ) 13.6 Hz, J 2′′,3′ ) 4.2
Hz, H2′′), 2.29 (3H, s, COCH3). 13C NMR (MeOH-d4): δ 173.71,
158.43, 157.21, 155.15, 153.78, 146.98, 144.80, 131.73, 129.97-
(br), 123.68, 90.75 (d, J 4′,5′ ) 40.1 Hz), 87.68, 73.66, 64.54,
42.82, 26.10. HRMS (M + H)+: calcd for C2413CH24N6O6
506.1869, found 506.1853.
J 5′′,C5′ ) 142.3 Hz, H5′′), 3.65 (1H, ddd, J 4′,5′ ) 3.7 Hz, J 5′,5′′
)
12.1 Hz, J 5′,C5′ ) 140.3 Hz, H5′), 2.22 (2H, m, H2′, H2′′). 13C
NMR (MeOH-d4): δ 166.37, 152.34, 137.15, 111.50, 88.76 (d,
J 4′,5′ ) 41.6 Hz), 86.23, 72.17, 62.81, 41.15, 12.43; HRMS (M
+ H)+: calcd for C93CH14N2O5 244.1015, found 244.0992.
Ack n ow led gm en t. We are grateful to Professor
Emeritus Yoshiharu Ishido for helpful discussions. This
work was supported in part by a Grant-in-Aid for
Scientific Research (C)(No. 116772117) from the Min-
istry of Education, Culture, Sports, Science and Tech-
nology, J apan, and in part by Hayashi Memorial Foun-
dation for Female Natural Science J apan.
N4-Ben zoyl-2′-d eoxy[5′-13C]cytid in e (17CBz). Compound
16CBz (57 mg, 0.1 mmol) was treated similarly to 17ABz to give
1
17CBz (31.8 mg, 96%) as a foam. H NMR (MeOH-d4): δ 8.54
(1H, d, J 5,6 ) 7.5 Hz, H6), 7.5-8.0 (6H, m, H5, Ph-H), 6.24
(2H, dd, J 1′,2′ ) 6.3 Hz, J 1′,2“ ) 6.2 Hz, H1′), 4.39 (1H, m, H3′),
4.01 (1H, m, H4′), 3.84 (1H, ddd, J 4′,5′′ ) 3.2 Hz, J 5′,5′′ ) 12.1
Hz, J 5′′,C5′ ) 142.9 Hz, H5′′), 3.75 (1H, ddd, J 4′,5′ ) 3.8 Hz, J 5′,5′′
) 12.1 Hz, J 5′,C5′ ) 140.1 Hz, H5′), 2.52 (1H, ddd, J 1′,2′′ ) 6.2
Hz, J 2′,2′′ ) 13.7 Hz, J 2′′,3′ ) 4.3 Hz, H2′′), 2.20 (1H, ddd, J 1′,2′
) 6.3 Hz, J 2′,2′′ ) 13.7 Hz, J 2′,3′ ) 6.3 Hz, H2′). 13C NMR (MeOH-
d4): δ 169.09, 164.77, 157.86, 146.45, 134.74, 134.08, 129.83,
129.15, 98.27, 89.52 (d, J 4′,5′ ) 41.7 Hz), 88.76, 71.64, 62.45,
42.54. HRMS (M + H)+: calcd for C1513CH17N3O5 333.1280,
found 333.1250.
Su p p or tin g In for m a tion Ava ila ble: Copies of the 1H
NMR, 13C NMR, and mass spectra or analytical data of
compounds 2, 3, 4-Bn , and 4-Me. This material is available
free of charge via the Internet at http://pubs.acs.org.
J O016281Q
J . Org. Chem, Vol. 67, No. 15, 2002 5151