Total synthesis of spicamycin amino nucleoside.

Article abstract of DOI:10.1021/ol005715l

[formula: see text] The first total synthesis of spicamycin amino nucleoside 2 has been achieved. The aminoheptose unit 5 was prepared stereoselectively from myo-inositol, and the characteristic N-glycoside linkage was constructed by way of Pd-catalyzed coupling reaction of 5 with 6-chloropurine derivative 6.

Full text of DOI:10.1021/ol005715l

ORGANIC
LETTERS
2000
Vol. 2, No. 8
1137-1140
Total Synthesis of Spicamycin Amino
Nucleoside
Tamotsu Suzuki, Sayaka Tanaka, Iwao Yamada, Yoshiaki Koashi,
Kazue Yamada, and Noritaka Chida*
Department of Applied Chemistry, Faculty of Science and Technology,
Keio UniVersity, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
chida@applc.keio.ac.jp
Received February 23, 2000
ABSTRACT
The first total synthesis of spicamycin amino nucleoside 2 has been achieved. The aminoheptose unit 5 was prepared stereoselectively from
myo-inositol, and the characteristic N-glycoside linkage was constructed by way of Pd-catalyzed coupling reaction of 5 with 6-chloropurine
derivative 6.
In 1983, Hayakawa and co-workers reported the isolation
of spicamycin 1 from the culture broth of Streptomyces
alanosinicus as a potent differentiation inducer of HL-60
human promyelocytic leukemia cells.1 The structural study
by spectral and degradation methods revealed that spicamycin
consists of a novel aminoheptose, adenine, glycine, and fatty
acids, and is a mixture of several congeners that differ in
their fatty acid moieties.1 Mild acid hydrolysis of spicamycin
afforded spicamycin amino nucleoside (SAN, 2),2 whose
absolute structure was determined by X-ray analysis and
copper complex (TACu) method to be 6-(4-amino-4-deoxy-
L-glycero-â-L-manno-heptopyranosylamino)-9H-purine.3 These
studies showed that the structure of 1 is quite unique among
the nucleoside antibiotics with respect to the glycosylation
site: while conventional adenine-nucleoside antibiotics bear
a sugar at the N(9) position, the present compound is
glycosylated at the C(6)-amino group of adenine with the
â-manno anomeric configuration.
Extensive structure-activity relationship studies2,4 of spi-
camycin analogues prepared by semisynthetic methods
employing the condensation of 2 with various amino acids
and fatty acids proved that SAN 2 is a useful precursor for
the synthesis of spicamycin and its analogues and generated
the promising compounds, KRN 5500 35 and SPM VIII 4,2
which showed potent antitumor activities against human
gastric cancer SC-9 and COL-1 colon carcinoma xenografts,
respectively. Although such significant biological activity and
an intriguing structure have attracted the considerable
synthetic attention, neither a total synthesis of 1 nor even
the preparation of the aminoheptose moiety has been
(1) (a) Hayakawa, Y.; Nakagawa, M.; Kawai, H.; Tanabe, K.; Nakayama,
H.; Shimazu, A.; Seto, H.; Otake, N. J. Antibiot. 1983, 36, 934. (b)
Hayakawa, Y.; Nakagawa, M.; Kawai, H.; Tanabe, K.; Nakayama, H.;
Shimazu, A.; Seto, H.; Otake, N. Agric. Biol. Chem. 1985, 49, 2685.
(2) Kamishohara, M.; Kawai, H.; Odagawa, A.; Isoe, T.; Mochizuki, J.;
Uchida, T.; Hayakawa, Y.; Seto, H.; Tsuruo, T.; Otake, N. J. Antibiot. 1993,
46, 1439.
(3) Sakai, T.; Shindo, K.; Odagawa, A.; Suzuki, A.; Kawai, H.;
Kobayashi, K.; Hayakawa, Y.; Seto, H.; Otake, N. J. Antibiot. 1995, 48,
899.
(4) (a) Kamishohara, M.; Kawai, H.; Odagawa, A.; Isoe, T.; Mochizuki,
J.; Uchida, T.; Hayakawa, Y.; Seto, H.; Tsuruo, T.; Otake, N. J. Antibiot.
1994, 47, 1305. (b) Sakai, T.; Kawai, H.; Kamishohara, M.; Odagawa, A.;
Suzuki, A.; Uchida, T.; Kawasaki, T.; Tsuruo, T.; Otake, N. J. Antibiot.
1995, 48, 504. (c) Sakai, T.; Kawai, H.; Kamishohara, M.; Odagawa, A.;
Suzuki, A.; Uchida, T.; Kawasaki, T.; Tsuruo, T.; Otake, N. J. Antibiot.
1995, 48, 1467.
(5) Kamishohara, M.; Kawai, H.; Sakai, T.; Isoe, T.; Hasegawa, K.;
Mochizuki, J.; Uchida, T.; Kataoka, S.; Yamaki, H.; Tsuruo, T.; Otake, N.
Oncol. Res. 1994, 6, 383.
10.1021/ol005715l CCC: $19.00 © 2000 American Chemical Society
Published on Web 03/25/2000

completed. Only a few reports on syntheses of compounds
related to spicamycin have appeared: Fleet reported the
synthesis of spicamycin analogues in which the aminoheptose
unit was replaced by 4-amino-4-deoxy-L- and D-rhamnose
(rhamnospicamycin),6 and Acton disclosed the preparation
of analogues with 4-amino-4-deoxy- and 4-amino-4,6-
dideoxy-L-glucose.7 Both syntheses employed the multistep
procedures, in which 6-(pyranosylamino)-4-amino-5-nitroro-
pyrimidines, prepared by the coupling reaction of pyrano-
sylamines with 6-amino-4-chloro-7 or 4,6-dichloro-5-
nitropyrimidine6 were involved as the key intermediates, for
the construction of the N-glycosidic structures. Here, we
report the first total synthesis of SAN 2 starting from
naturally abundant cyclitol, myo-inositol.
to be effective for the construction of the spicamycin-type
N-glycosides and successfully provided protected 6-(â-D-
mannopyranosylamino)purine by a one-step reaction in good
yield. The amine 5 was planned to be prepared from acyclic
precursor 7, which would be generated by the carbon
elongation of aldehyde 8. The aldehyde 8 would derive from
the ring cleavage reaction of a highly functionalized cyclo-
hexane derivative 9, which was envisioned as arising from
myo-inositol 10.
The known racemic diol9 DL-11, prepared from 10 in a
one-step reaction, was converted into protected diol DL-12
in 45% yield from DL-11 (Scheme 1). The equatorial
Our retrosynthetic analysis (Figure 1) suggested that
N-glycosidic structure in 2 would be constructed by the Pd-
catalyzed coupling reaction of protected glycosylamine 5
Scheme 1a
a Conditions: (a) 1,1-dimethoxycyclohexane, p-TsOH, DMF (see
ref 9); (b) NaH, BnCl, DMF; (c) p-TsOH, EtOH, 45 °C; (d) NaH,
PMBCl, Bu4NI, THF-DMF, rt; (e) AcOH-H2O (4:1), 50 °C; (f)
(+)-L-O-acetylmandelic acid, DCC, DMAP, CH2Cl2, -20 °C; (g)
NaOMe, MeOH, 50 °C.
hydroxy group in DL-12 was selectively acylated by a
treatment with an equimolar amount of L-O-acetyl mandelic
acid10 in the presence of DCC and 4-(dimethylamino)pyridine
(DMAP) to provide a pair of chiral diastereoisomers, 13 and
14, which were easily separated by silica gel chromatography
followed by recrystallization, in 41 and 37% isolated yields,
respectively. Deacylation of 13 gave 12D (85% yield) and
that of 14 afforded the enantiomer 12L (89%).11
Synthesis of the aminoheptose moiety commenced with
12D (Scheme 2), whose equatorial hydroxy group was
selectively benzoylated, and the remaining hydroxy group
was converted into azide via mesylate to give 15 in 72%
Figure 1. Structures of spicamycin and related compounds, and
retrosynthetic route to SAN (SEM ) 2-(trimethylsilyl)ethoxy-
methyl).
(9) (a) Garegg, P. J.; Iversen, T.; Johansson, R.; Lindberg, B. Carbohydr.
Res. 1984, 130, 322. (b) Jiang, C.; Baker, D. J. Carbohydr. Chem. 1986, 5,
615.
(10) Chida, N.; Yamada, E.; Ogawa, S. J. Carbohydr. Chem. 1988, 7,
555.
with 6-chloro-9-SEM-purine 6. This straightforward meth-
(11) The absolute configuration and the optical purity of 12D and 12L
were determined by their transformation into the known compounds, 1D-
and 1L-1,4,5,6-tetra-O-benzyl-myo-inositol, respectively. For 1D-isomer
prepared from 12D: mp 144-145 °C.; [R]23D +25 (c 1, CHCl3), lit. (Shvets,
V. I.; Klyashchitskii, B. A.; Stepanov, A. E.; Evstgneeva, R. P. Tetrahedron,
29, 1973, 331) mp 140-142 °C, [R]20D +25 (c 0.18, CHCl3). For 1L-isomer
odology, recently reported from this laboratory,8 was proved
(6) (a) Martin, A.; Butters, T. D.; Fleet, G. W. J. Chem. Commun. 1998,
2119. (b) Martin, A.; Butters, T. D.; Fleet, G. W. J. Tetrahedron Asymmetry
1999, 10, 2343.
(7) Acton, E. M.; Ryan, K. J.; Luetzow, A. E. J. Med. Chem. 1977, 20,
1362.
(8) Chida, N.; Suzuki, T.; Tanaka, S.; Yamada, I. Tetrahedron Lett. 1999,
40, 2573.
from 12L: mp 144-145 °C.; [R]25 -24 (c 1, CHCl3), lit. mp 141-143
D
°C; [R]20D -24.3 (c 1.3, CHCl3). The optical purity of 12D and 12L were
also confirmed to be >98% ee, respectively, by chiral column analysis
(chiralcel OD).
1138
Org. Lett., Vol. 2, No. 8, 2000

R-anomer in 81% yield. Treatment of 20 with trimethylsilyl
bromide16 gave unstable R-bromoheptose derivative 21,
which was then reacted with trimethylsilyl azide in the
presence of TBAF17 to afford â-anomeric azide 2218 in 81%
yield from 20. When diazide compound 22 was subjected
to hydrogenation conditions in the presence of Lindlar
catalyst in toluene, only anomeric azide group was reduced
to give â-heptopyranosylamine 515,18 in 78% yield.
Scheme 2a
Having finished the preparation of the heptopyranosyl-
amine unit 5 with correct stereocenters, we explored the
construction of the characteristic N-glycoside (Scheme 3).
Scheme 3
a Conditions: (a) BzCl, pyridine, rt; (b) MsCl, pyridine, rt; (c)
NaN3, DMF, 100 °C; (d) NaOMe, MeOH, rt; (e) KOAc, 18-crown-
6, DMF, 100 °C; (f) DDQ, wet CH2Cl2, 0 °C; (g) NaIO4, MeOH-
H2O, rt; (h) NaBH4, MeOH, 0 °C; (i) 2,2-dimethoxypropane,
p-TsOH, DMF, rt; (j) DMSO, DCC, TFA, pyridine, PhH, rt; (k)
CH2dCHLi, Et2O, -115 °C; (l) NaH, BnBr, DMF, 0 °C; (m) O3,
CH2Cl2, -78 °C, then Me2S; (n) p-TsOH, MeOH, 0 °C; (o) Ac2O,
pyridine, rt; (p) TMSBr, CHCl3, rt; (q) TMSN3, Bu4NF, THF, rt;
(r) H2 (1 atm), Lindlar catalyst, toluene, rt.
Reaction of amine 5 with 6 in the presence of Pd2(dba)3 (10
mol %), (R)-(+)-BINAP (20 mol %), and NaOtBu (150 mol
%) in toluene at 130 °C in a sealed tube for 2.5 h8,19 gave
the desired coupling product, fully protected 6-(â-pyranos-
ylamino)-9-SEM-purine 2315,18 in 65% yield.20 Deacylation
of 23, followed by treatment with excess BBr3 in CH2Cl2 at
yield. After deprotection of the benzoyl group in 15, the
resulting alcohol was transformed into inverted acetate 1612
(64%). Removal of O-PMB and O-acetyl groups in 16 gave
triol 9 in 95% yield.
Periodate oxidation of 9, followed by reduction with
NaBH4, and subsequent treatment with 2,2-dimethoxypro-
pane provided azidoalditol 18 in 80% yield from 9. Moffatt
oxidation of 18 gave unstable aldehyde 8, which, without
isolation, was immediately reacted with vinyllithium13 in
Et2O at -115 °C to afford Felkin-Anh product 19 as the
major isomer.14 Protection of the hydroxy group in 19
provided tri-O-benzyl ether 7 in 68% yield from 18.
Ozonolysis of 7 (Me2S workup), followed by acid hydrolysis
and subsequent treatment with acetic anhydride and pyridine,
afforded 4-azidoheptopyranosyl acetate 2015 as the single
12.0 Hz), 6.17 (d, 1 H, J ) 2.0 Hz), 7.26-7.39 (m, 15 H); 13C NMR (75
MHz, CDCl3) δ 20.9, 21.0, 57.8, 64.0, 71.8, 71.9, 72.5, 72.9, 73.9, 77.4,
77.5, 91.5, 127.6, 127.8, 127.9, 128.0, 128.0, 128.3, 128.5, 137.2, 137.4,
1
137.9, 168.7, 170.7. For 5: [R]22 +7 (c 1, CHCl3); H NMR (300 MHz,
D
CDCl3) δ 1.99 (s, 3 H), 2.33 (bs, 2 H), 3.30 (dd, 1 H, J ) 1.5 and 10.1
Hz), 3.47 (dd, 1 H, J ) 2.7 and 9.8 Hz), 3.85-3.90 (m, 2 H), 3.91 (dd, 1
H, J ) 9.8 and 10.1 Hz), 4.05 (d, 1 H, J ) 1 Hz), 4.23 (dd, 1 H, J ) 6.8
and 12.0 Hz), 4.35 (dd, 1 H, J ) 4.4 and 12.0 Hz), 4.41-5.04 (m, 6 H),
7.28-7.40 (m, 15 H); 13C NMR (75 MHz, CDCl3) δ 20.9, 58.7, 63.8, 72.2,
72.5, 74.9, 75.4, 75.8, 77.1, 82.9, 83.4, 127.7, 128.0, 128.1, 128.3, 128.3,
1
128.6, 137.2, 137.9, 138.3, 170.7. For 23: [R]22 +4 (c 0.84, CHCl3); H
D
NMR (300 MHz, MeOH-d4 at 55 °C) δ -0.06 (s, 9 H), 0.90 (t, 2 H, J )
7.8 Hz), 1.96 (s, 3 H), 3.61 (dd, 1 H, J ) 1.7 and 10.0 Hz), 3.65 (t, 2 H,
J ) 7.8 Hz), 3.85 (dd, 1 H, J ) 2.7 and 10.0 Hz), 3.92 (ddd, 1 H, J ) 1.7,
4.4, and 7.1 Hz), 4.04 (dd, 1 H, J ) 10.0 and 10.0 Hz), 4.20 (dd, 1 H, J )
2.7 and <1 Hz), 4.20 (dd, 1 H, J ) 7.1 and 11.7 Hz), 4.29 (dd, 1 H, J )
4.4 and 11.7 Hz), 4.53-5.02 (m, 6 H), 5.61 (s, 2 H), 5.85 (bs, 1 H, J < 1
Hz), 7.20-7.48 (m, 15 H), 8.21 and 8.34 (2s, each 1 H); 13C NMR (75
MHz, MeOH-d4, rt) δ -1.5, 14.2, 20.9, 58.4, 60.4, 64.1, 67.2, 72.0, 72.6,
73.6, 73.9, 74.6, 76.2, 77.6, 82.7, 119.7, 127.5, 127.7, 127.8, 127.9, 128.0,
128.1, 128.2, 128.3, 128.4, 128.5, 128.6, 137.1, 137.7, 138.1, 140.8, 150.4,
153.0, 153.3, 170.7; FAB-MS, m/z 795 (M + H)+.
(12) All new compounds described in this paper were characterized by
300 MHz 1H NMR, 75 MHz 13C NMR, IR, and mass spectrometric and/or
elemental analyses.
(13) Vinyllithium was prepared by the procedure reported by Seyferth
and Weiner; see, Seyferth, D.; Weiner, M. A. J. Am. Chem. Soc. 1961, 83,
3583.
(14) Although the formation of C(3) epimer of 19 was detected in the
1H NMR spectrum (19/(C(3) epimer: >8/1), this could not be isolated.
(16) Gillard, J. W.; Israel, M. Tetrahedron Lett. 1981, 22, 513.
(17) Soli, E. D.; Manoso, A. S.; Patterson, M. C.; DeShong, P.; Favor,
D. A.; Hirschmann, R.; Smith, A. B., III. J. Org. Chem. 1999, 64, 3171.
(18) The observed NOE between H-1 and H-2, H-1 and H-3, and H-1
and H-5 in the sugar portion clearly supported the â-manno configuration.
(19) Wolfe, J. P.; Wagaw, S.; Buchwald, S. L. J. Am. Chem. Soc. 1996,
118, 7215.
1
(15) Selected data for 20: [R]22 -47 (c 0.72, CHCl3); H NMR (300
D
MHz, CDCl3) δ 2.01, 2.04 (2s, each 3 H), 3.66 (dd, 1 H, J ) 1.3 and 10.0
Hz), 3.67 (dd, 1 H, J ) 2.0 and 2.9 Hz,), 3.72 (dd, 1 H, J ) 2.9 and 10.0
Hz), 3.89 (ddd, 1 H, J ) 1.3, 4.4, and 7.1 Hz), 4.16 (dd, 1 H, J ) 10.0 and
10.0 Hz), 4.24 (dd, 1 H, J ) 7.1 and 12.0 Hz), 4.34 (dd, 1 H, J ) 4.4 and
12.0 Hz), 4.57 and 4.70 (2s, each 2 H), 4.62 and 4.71 (2d, each 2 H, J )
Org. Lett., Vol. 2, No. 8, 2000
1139

-78 °C to 0 °C (K2CO3-MeOH workup) provided SAN 2
in 58% yield after purification with silica gel chromatography
and reverse-phase chromatography. It is noteworthy that
azide group in 23 was unexpectedly reduced to amine under
+21.7 (c 0.36, DMF)22} were fully identical with those of
SAN, prepared from spicamycin by degradation.
In summary, the first total synthesis of SAN 2 starting
from myo-inositol was accomplished. This synthesis fully
confirmed the proposed unique structure of the biologically
important natural product and established the synthetic
pathway to spicamycin and its analogues. The efficiency of
the Pd-catalyzed coupling reaction of glycosylamines with
6-chloropurine is also noteworthy for the construction of the
novel N-glycoside.
1
the BBr3 conditions. The H NMR spectra18,21 as well as
physical properties of synthetic 2 {mp 154-156 °C (dec)
(DMF-toluene); [R]23 +21.5 (c 0.14, DMF): authentic
D
sample, mp 154-156 °C (dec) (DMF-toluene)22; [R]25
D
(20) When this reaction was terminated at 1 h, a mixture of 23 and its
R-anomer (3:1) was obtained in 40% yield, revealing that anomerization
of 5 and 23 had taken place during the coupling reaction, and â-anomer 23
is the thermodynamically favored product.
Acknowledgment. We thank Dr. K. Akimoto (Pharma-
ceutical Research Laboratory, Kirin Brewery Co., Ltd.,
Takasaki, Japan) for providing us with the authentic SAN
prepared from natural spicamycin. We also thank Prof. Y.
Hayakawa (Institute of Molecular and Cellular Biosciences,
University of Tokyo, Japan) for valuable information.
(21) 1H NMR (300 MHz, MeOH-d4) δ 3.02 (dd, 1 H, J ) 10.0 and 10.0
Hz, H-4′), 3.43 (dd, 1 H, J ) 6.4 and 10.0 Hz, H-5′), 3.52 (dd, 1 H, J )
3.2 and 10.0 Hz, H-3′), 3.61 (d, 2 H, J ) 4.2 Hz, H-7′), 3.79 (dt, 1 H, J )
4.2 and 6.4 Hz, H-6′), 3.94 (dd, 1 H, J ) 3.2 and <1 Hz, H-2′), 5.64 (bs,
1 H, H-1′), 8.12 (s, 1 H, H-8), 8.29 (s, 1 H, H-2); 13C NMR {75 MHz,
MeOH-d4-DMF (1: 1 v/v)} δ 53.0, 64.6, 71.4, 75.9, 76.4, 77.3, 80.3, 119.2,
143.0, 150.5, 153.1, 154.0; FAB-MS, m/z 327 (M + H)+.
(22) These data of SAN were measured in our laboratory on material of
natural origin, kindly supplied by Dr. Akimoto (Kirin Brewery Co., Ltd.).
OL005715L
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Org. Lett., Vol. 2, No. 8, 2000