heating 20 with DBU in DMF to provide dihydrofuran 21, [a]2D7
+105.3 (c 1.02, CHCl3), regioselectively in 89% yield. The
TEMP group of 21 was reductively removed with zinc dust in
methanolic NH4Cl to afford the primary alcohol 22, [a]2D8
+195.8 (c 0.99, CHCl3), in 92% yield. Since Jones oxidation of
22 proceeded inefficiently, it was oxidized using Swern
conditions14 followed by sodium chlorite15 to give carboxylic
acid 23, [a]2D7 +175.4 (c 0.57, MeOH), in 89% yield. Finally
removal of the BnOCO group of 23 with thioanisole in TFA
produced (+)-furanomycin 24, mp 222–224 °C, [a]2D6 +136.0 (c
0.4, H2O), in 97% yield, the physical and spectroscopic data of
which were identical with those previously reported.
X
N
I
10
H
10
H
4
4
O
O
N
6
6
O
CCl3
O
CCl3
H
H
13 X = I
14
15 X = HgBr
16 X = OH
17 X = H
18 X = OTEMP
i
ii
18
15
11
Financial support from the Korea Science and Engineering
Foundation (971-0302-010-2) is gratefully acknowledged.
iii, iv
NHZ
NHZ
Notes and References
H
H
O
O
OTEMP
OR
vi
† E-mail: shkang@kaist.ac.kr
1 K. Katagiri, K. Tori, Y. Kimura, T. Yoshida, T. Nagasaki and
H. Minato, J. Med. Chem., 1967, 10, 1149.
2 T. Kohno, D. Kohda, M. Haruk, S. Yokoyama and T. Miyazawa, J. Biol.
Chem., 1990, 265, 6931.
X
21 R = TEMP
22 R = H
vii
19 X = β-OH
20 X = α-I
v
3 R. J. Parry and H. P. Buu, J. Am. Chem. Soc., 1983, 105, 7446;
R. J. Parry, R. Turakhia and H. P. Buu, J. Am. Chem. Soc., 1988, 110,
4035.
4 M. Shiro, H. Nakai, K. Tori, J. Nishikawa, Y. Yoshimura and
K. Katagiri, J. Chem. Soc., Chem. Commun., 1980, 375.
5 M. M. Joullie, P. C. Wang and J. E. Semple, J. Am. Chem. Soc., 1980,
102, 887; J. E. Semple, P. C. Wang, Z. Lysenko and M. M. Joullie,
J. Am. Chem. Soc., 1980, 102, 7505.
6 I. Savage and E. J. Thomas, J. Chem. Soc., Chem. Commun., 1989, 717;
S. H. Kang and H.-W. Choi, Chem. Commun., 1996, 1521.
7 P. J. Garegg and B. Samuelsson, J. Chem. Soc., Chem. Commun., 1979,
978; P. J. Garegg and B. Samuelsson, J. Chem. Soc., Perkin Trans. 1,
1980, 2866; P. J. Garegg, R. Johansson, C. Ortega and B. Samuelsson,
J. Chem. Soc., Perkin Trans. 1, 1982, 682.
8 H. O. House, C.-Y. Chu, J. M. Wilkins and M. J. Umen, J. Org. Chem.,
1975, 40, 1460; E. Erdik, Tetrahedron, 1984, 40, 641.
9 T. L. B. Boivin, Tetrahedron, 1987, 43, 3309; J.-C. Harmange and
B. Figadere, Tetrahedron: Asymmetry, 1993, 4, 1711.
10 R. P. Quirk and R. E. Lea, J. Am. Chem. Soc., 1976, 98, 5973;
M. C. Benhamou, G. Etemad-Moghadam, V. Speziale and A. Lattes,
Synthesis, 1979, 891; K. E. Harding, R. Stephens and D. R.
Hollingsworth, Tetrahedron Lett., 1984, 25, 4631.
11 G. Cardillo and M. Orena, Tetrahedron, 1990, 46, 3321.
12 A. R. Chamberlin, R. M. Mulholland, Jr., S. D. Kahn and W. J. Hehre,
J. Am. Chem. Soc., 1987, 109, 672.
13 C. L. Hill and G. M. Whitesides, J. Am. Chem. Soc., 1974, 96, 870.
14 A. J. Mancuso and D. Swern, Synthesis, 1981, 165.
15 B. S. Bal, W. E. Childers and H. W. Pinnik, Tetrahedron, 1981, 37,
2091.
viii, ix
NHP
H
O
TEMP =
N
CO2H
23 P = Z
24 P = H
x
Scheme 2 Reagents and conditions: i, Hg(OCOCF3)2, K2CO3, THF, 0 °C,
then aq. KBr; ii, TEMPO, Et3B, LiBH4, THF, 20 °C; iii, 6 m HCl, MeOH,
THF, reflux; iv, BnOCOCl, K2CO3, MeOH, 20 °C; v, I2, PPh3, DMAP,
PhH, CH2Cl2, 0 °C, then 60 °C; vi, DBU, DMF, 80 °C; vii, Zn, NH4Cl, H2O,
MeOH, 80 °C; viii, (COCl)2, DMSO; ix, NaClO2, NaH2PO4, 2-methylbut-
2-ene, ButOH, H2O, 20 °C; x, PhSMe, TFA, 50 °C
protected with benzyl chloroformate to afford carbamate 19,
[a]2D5 212.0 (c 1.00, CHCl3), in 95% overall yield.
The dihydrofuryl ring could not be formed by the basic or
pyrolytic elimination reaction of the mesylate, triflate or
xanthate derivatives of 19. In addition their substitution reaction
with iodide or phenylselenide anion did not yield the expected
product. Various experimental attempts revealed that iodide 20,
[a]2D5 265.2 (c 0.99, CHCl3) could be prepared in 76% yield by
treating 19 with I2 and PPh3 in the presence of DMAP in a
mixture of benzene and CH2Cl2, while the reaction using
imidazole7 instead of DMAP resulted in a poor chemical yield
of 35%. The ensuing elimination reaction was effected by
Received in Cambridge, UK, 27th January 1998; 8/00727F
762
Chem. Commun., 1998