288
D. Matsuura et al.
LETTER
corresponding labile primary amine. This was then quick- In summary, the process described here involves no sepa-
ly effected by acetylation reaction to furnish the amide 9 ration of stereoisomers and was substantially performed
in satisfactory two-step yield. Apart from the troublesome under ambient conditions through entire sequence until
synthetic methods hitherto reported,1,3 we envisioned a natural furanodictine B was synthesized. In addition, it is
novel and more concise manner to achieve the total syn- easily applicable to the preparation in relatively large
thesis of furanodictine B (2), which is as follows. After amount since the starting material is commercially avail-
hydrolysis of the methyl glycoside part of 9 in refluxing able and the synthetic pathway is short and operationally
70% acetic acid solution, the resulting acetal was protect- simple. Additional studies to the total synthesis of the
ed with TBSCl to give the silyl ether 10 in 78% two-step other furanodictine A starting from D-glucuronolactone
yield. Next, 10 was submitted to deprotection of the ben- are in progress and will be reported elsewhere.
zyl group and esterification of the remaining hydroxyl
function with the desired isovaleric acid counter part in
Acknowledgment
the presence of EDCI [1-ethyl-3-(3-dimethylamino-
propyl)carbodiimide hydrochloride] and DMAP,8 provid-
This work was supported in part by a Grant-in-Aid for Scientific
Research from Japan Society for the Promotion of Science.
ing O-TBS-protected furanodictine B (11) in 88% yield
through a two-step sequence. Finally, 11 was readily
deprotected with Bu4NF to complete the total synthesis of
References
the natural type of 2, [a]D26 +104.8 (c 0.86, CHCl3) {nat-
(1) Kikuchi, H.; Saito, Y.; Komiya, J.; Takaya, Y.; Honma, S.;
ural 2, [a]D +85.6 (c 0.250, CHCl3)1 and synthetic 2,
25
Nakahata, N.; Ito, A.; Oshima, Y. J. Org. Chem. 2001, 66,
6982.
[a]D25 +98.4 (c 0.808, CHCl3)1},9 in 96% yield.
(2) Maeda, Y.; Inouye, K.; Takeuchi, I. Dictyostelium: A Model
BnO
BnO
BnO
BnO
H
H
System for Cell and Developmental Biology, Frontiers
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Tokyo, 1997.
O
O
O
a
b
OCH3
OCH3
O
O
O
O
(3) Yoda, H.; Suzuki, Y.; Takabe, K. Tetrahedron Lett. 2004,
45, 1599.
H
H
H
H
OH
N3
7
8
(4) During our synthetic studies of these substances, the
synthetic approach to the intermediate of furanodictine B(2)
starting from D-glucose has just appeared. See: Mereyala, H.
B.; Baseeruddin, M.; Koduru, S. R. Tetrahedron:
Asymmetry 2004, 15, 3457.
(5) (a) Martinelli, M. J.; Vaidyanathan, R.; Khau, V. V.
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Vaidyanathan, R. Org. Lett. 1999, 1, 447.
(6) Direct deoxgenation with Et3SiH-Lews acid system after
reduction of the lactone 4 to the corresponding lactol
derivative, however, resulted in the preparation of the
complex mixture.
O
c
d
OCH3
OTBS
H
H
NHAc
NHAc
9
10
O
O
H
H
H
H
O
O
e
O
O
OTBS
NHAc
OH
NHAc
O
O
11
Furanodictine B (2)
(7) (a) Homer, L.; Gross, A. Justus Liebigs Ann. Chem. 1955,
591, 117. (b) Hankovszky, H. O.; Hideg, K.; Lex, L.
Synthesis 1981, 147. (c) For recent examples, see: Lucas,
S.; Luther, L. M.; Burke, S. D. Org. Lett. 2004, 6, 2965. (d)
See also: Eipert, M.; Maichle-Moessmer, C.; Maier, M. E.
Tetrahedron 2003, 59, 7949.
Scheme 2 Reagents and conditions: (a) 1, Tf2O, pyridine, CH2Cl2;
2, NaN3, DMF, 60 °C, 61% (two steps); (b) 1, PPh3, H2O, THF–
CH2Cl2 (3:1); 2, Ac2O, pyridine, CH2Cl2, 65% (two steps); (c) 1, 70%
HOAc, 90 °C; 2, TBSCl, imidazole, DMF, 78% (two steps); (d) 1, Pd/
C, H2, CH3CO2Et, quant.; 2, isovaleric acid, EDCI, DMAP, CH2Cl2,
88%; (e) Bu4NF, THF; 96%.
(8) Yoda, H.; Nakaseko, Y.; Takabe, K. Tetrahedron Lett. 2004,
45, 4217; and references cited therein.
(9) Synthesized furanodictine B in this report was a mixture
[a:b = 1:2.4 (natural; a:b = 2:3)1] of the two anomers.
Synlett 2005, No. 2, 287–288 © Thieme Stuttgart · New York