Total synthesis of C-glycosylangucycline, urdamycinone B, using an unprotected sugar

Article abstract of DOI:10.1021/jo990648y

The total synthesis of urdamycinone B (1), a prototypical member of the C-glycosylangucycline antibiotics, was achieved by a novel and effective strategy without any protecting group in the sugar moiety. The unprotected C- glycosyljuglone 6 was effectively synthesized by the aryl C-glycosidation of 1,5-naphthalenediol (16) with the totally unprotected D-olivose (8) and the subsequent regioselective photooxygenation of the resultant C- glycosylnaphthalenediol 17. On the other hand, the diene 7 was prepared from 3-methyl-2-cyclohexen-1-one (9) in a short step via the cross-coupling of the vinyl triflate 20 and vinylbutyltin (21) and the Wittig reaction of the aldehyde 24 and the phosphine 25. Finally, the regioselective Diels-Alder reaction of the unprotected C-glycosyljuglone 6 and the diene 7, followed by the regioselecitive introduction of the ketone function at the C1 position, led to the total synthesis of 1.

Full text of DOI:10.1021/jo990648y

J . Org. Chem. 1999, 64, 7101-7106
7101
Tota l Syn th esis of C-Glycosyla n gu cyclin e, Ur d a m ycin on e B, Usin g
a n Un p r otected Su ga r
Goh Matsuo,1 Yuko Miki, Masaya Nakata, Shuichi Matsumura, and Kazunobu Toshima*
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi,
Kohoku-ku, Yokohama 223-8522, J apan
Received April 20, 1999
The total synthesis of urdamycinone B (1), a prototypical member of the C-glycosylangucycline
antibiotics, was achieved by a novel and effective strategy without any protecting group in the
sugar moiety. The unprotected C-glycosyljuglone 6 was effectively synthesized by the aryl
C-glycosidation of 1,5-naphthalenediol (16) with the totally unprotected D-olivose (8) and the
subsequent regioselective photooxygenation of the resultant C-glycosylnaphthalenediol 17. On the
other hand, the diene 7 was prepared from 3-methyl-2-cyclohexen-1-one (9) in a short step via the
cross-coupling of the vinyl triflate 20 and vinylbutyltin (21) and the Wittig reaction of the aldehyde
24 and the phosphine 25. Finally, the regioselective Diels-Alder reaction of the unprotected
C-glycosyljuglone 6 and the diene 7, followed by the regioselecitive introduction of the ketone
function at the C1 position, led to the total synthesis of 1.
In tr od u ction
The angucyclines with a unique benz[a]anthraquinone
as a common structure are a rapidly growing new class
of antibiotics. They show a variety of biological activities
including antitumor activity and enzyme inhibition.2 The
C-glycoside structure is uniquely involved in some mem-
bers of this class as shown in Figure 1. Among them,
urdamycinone B (1), a prototypical member of the C-
glycosylangucyclines, which is obtained from antibiotic
urdamycin B (2) by careful cleavage of the two O-
glycoside moieties, also exhibits antitumor activity.3 The
elegant total syntheses of (-)-urdamycinone B, the enan-
tiomer of the natural urdamycinone B, and urdamycinone
B (1) have been reported by Yamaguchi4 and Sulikowski,5
F igu r e 1. Molecular structures of the representative angucy-
respectively. On the other hand, another C-glycosylan-
gucycline, C104 (3), was effectively synthesized by Suzuki
and Matsumoto.6 However, they are the only successful
achievements of the total synthesis of the full structure
of C-glycosylangucycline. Previously, we have disclosed
a novel and practical aryl C-glycosidation method using
an unprotected sugar. In this paper, we now report the
full account of the significant application of this method,
that is the highly effective total synthesis of urdamyci-
none B (1) by a novel strategy without using any
protecting group in the sugar moiety.7
cline antibiotics.
Syn th etic P la n
The retrosynthetic analysis of urdamycinone B (1) is
shown in Figure 2 along with our synthetic plan. The
target molecule 1 would be obtained by the conversion
of the masked tertiary alcohol into the free alcohol at the
C3 position and the introduction of the ketone function
using regioselective oxygenation at the C1 position in the
key intermediate 5. The key intermediate 5 was parti-
tioned into two Diels-Alder fragments, the dienophile 6
and the diene 7. The unprotected C-glycosyljuglone 6
would be synthesized by the aryl C-glycosidation method,
which was recently developed in our laboratories,8 using
the totally unprotected D-olivose (8) and an appropriate
glycosyl acceptor. On the other hand, the diene 7 would
be derived from 3-methylcyclohex-2-enone (9) via the
introduction of the masked tertiary alcohol by Fleming’s
method9 and the appropriate diene function for the
Diels-Alder reaction with 6. The highly effective syn-
thesis of the unprotected C-glycosyljuglone 6 and the
suitably protected diene 7 and the regioselective Diels-
Alder reaction of 6 and 7 leading to the total synthesis
of 1 are described in the following discussion.
(1) Taken in part from the Ph.D. Thesis of Goh Matsuo, Keio
University, 1997. Present address: The Institute of Physical and
Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198,
J apan.
(2) For a recent review of angucycline antibiotics, see: Rohr, J .;
Thiericke, R. Nat. Prod. Rep. 1992, 103.
(3) (a) Drautz, H.; Za¨hner, H.; Rohr, J .; Zeeck, A. J . Antibiot. 1986,
39, 1657. (b) Rohr, J .; Zeeck, A. J . Antibiot. 1987, 40, 459. (c) Henkel,
T.; Ciesiolka, T.; Rohr, J .; Zeeck, A. J . Antibiot. 1989, 42, 299. (d) Rohr,
J .; Beale, J . M.; Heinz, G. F. J . Antibiot. 1989, 42, 1151.
(4) Yamaguchi, M.; Okuma, T.; Horiguchi, A.; Ikeura, C.; Minami,
T. J . Org. Chem. 1992, 57, 1647.
(5) Boyd, V. A.; Sulikowski, G. A. J . Am. Chem. Soc. 1995, 117, 8472.
(6) Matsumoto, T.; Sohma, T.; Yamaguchi, H.; Kurata, S.; Suzuki,
K. Tetrahedron 1995, 51, 7347.
(7) For our preliminary communications of these works, see: (a)
Matsuo, G.; Miki, Y.; Nakata, M.; Matsumura, S.; Toshima, K. Chem.
Commun. 1996, 225. (b) Matsuo, G.; Matsumura, S.; Toshima, K.
Chem. Commun. 1996, 2173.
10.1021/jo990648y CCC: $18.00 © 1999 American Chemical Society
Published on Web 08/21/1999

7102 J . Org. Chem., Vol. 64, No. 19, 1999
Matsuo et al.
F igu r e 2. Retrosynthetic analysis of urdamycinone B (1).
Sch em e 1a
F igu r e 3. Aryl C-Glycosidatins of juglone (10) and D-olivose
(8).
Resu lts a n d Discu ssion
Syn th esis of th e Un p r otected C-Glycosylju glon e
6. C-Glycosyljuglone, a 5-hydroxy-1,4-naphthoquinone
bearing a C-glycoside at C6, is a common structural
feature among the many members of angucycline anti-
biotics. The C-glycosyljuglone is also a promising syn-
thetic intermediate for this class of antibiotics. Therefore,
several approaches to the C-glycosyljuglone have been
developed5,7b,10,11 and the syntheses of angucycline anti-
biotics via the C-glycosyljuglone have also been reported.5,7b
Our synthetic approach began with the synthesis of the
unprotected C-glycosyljuglone 6 using the totally unpro-
tected sugar, D-olivose (8). We first tried the direct aryl
C-glycosidation of juglone (10) with the totally unpro-
tected D-olivose (8) (Figure 3). However, this reaction did
not proceed by the activators, trimethylsilyl trifluo-
romethanesufonate (TMSOTf) or TMSOTf-AgClO4, which
were developed as novel and effective activators for the
a
Key: (a) MMCl, i-Pr2NEt, CH2Cl2, 0 °C, 1 h then 25 °C 0.5 h,
92%; (b) H2, 10% Pd-C, EtOAc, 25 °C, 1 h; (c) BnBr, NaH, DMF,
25 °C, 1 h, 86% from 11; (d) CF3CO2H, CH2Cl2, 25 °C, 1 h, 85%;
(e) TMSOTf, MeCN, 25 °C, 1 h, 27%; (f) H2, 10% Pd-C, MeOH,
25 °C, 1 h, 78%.
aryl C-glycosidations of unprotected sugars in our labo-
ratories.8 Furthermore, the corresponding protected C-
glycosyljuglones possessing benzyl or acetyl groups were
not obtained even when other appropriate aryl C-gly-
cosidation methods12 using protected sugars were applied
to this reaction. At this stage, it was considered that these
unfavorable results came from the extremely low reactiv-
ity of the glycosyl acceptor 10 due to the quinone
skeleton. Therefore, we next converted the juglone (10)
into the suitable glycosyl acceptor 14 as shown in Scheme
1. Thus, the juglone (10) was first protected using
methoxymethyl chloride (MMCl) and i-Pr2NEt in CH2-
Cl2 to give the protected juglone 11 in 92% yield. 11 was
then treated with a catalytic amount of 10% Pd-C under
a hydrogen atmosphere to afford the labile dihydroxy-
quinone 12, which was rapidly protected with benzyl
groups by the standard manner to give the protected
naphthol 13. The fully protected naphthol 13 was then
converted into the glycosyl acceptor 14 by the selective
deprotection of the methoxymethyl group under acidic
conditions. The aryl C-glycosidation of 14 and the un-
(8) For our studies on aryl C-glycosidation, see: (a) Toshima, K.;
Matsuo, G.; Tatsuta, K. Tetrahedron Lett. 1992, 33, 2175. (b) Toshima,
K.; Matsuo, G.; Ishizuka, T.; Nakata, M.; Kinoshita, M. J . Chem. Soc.,
Chem. Commun. 1992, 1641. (c) Toshima, K.; Matsuo, G.; Nakata, M.
J . Chem. Soc., Chem. Commun. 1994, 997. (d) Toshima, K.; Matsuo,
G.; Ishizuka, T.; Ushiki, Y.; Nakata, M.; Matsumura, S. J . Org. Chem.
1998, 63, 2307.
(9) Fleming, I.; Henning, R.; Plaut, H. J . Chem. Soc., Chem.
Commun. 1984, 29.
(10) Andrews, F. L.; Larsen, D. S. Tetrahedron Lett. 1994, 35, 8693.
(11) Matsumoto, T.; Sohma, H., Yamaguchi, H.; Suzuki, K. Chem.
Lett. 1995, 677.
(12) For recent reviews of C-glycosidation method, see: (a) Postema,
M. H. D. Tetrahedron 1992, 40, 8545. (b) J aramillo, C.; Knapp, S.
Synthesis 1994, 1. (c) Levy, D. E.; Tang, C. The Chemistry of
C-Glycosides; Pergamon Press: Oxford, 1995. (d) Du, Y.; Linhardt, R.
J . Tetrahedron 1998, 54, 9913.

Total Synthesis of C-Glycosylangucycline
J . Org. Chem., Vol. 64, No. 19, 1999 7103
Sch em e 2a
Ta ble 1. Oxygen a tion s of 17
17 25 °C8 6 + 6′
yield (%)
entry
reagent/(equiv)
CAN (2.5)
Fremy’s salt (3.6) MeOH
TTN (1.8)
solvent
time (h)
6
6′
1
2
3
4
CH3CN-H2O
0.5
1
0.5
1
0
10
1
25
55
74
0
MeOH
MeOH
Triton B (2.0)/O2
0
Ta ble 2. P h otooxygen a tion s of 17
17 O , sunlight8 6 + 6′
2
12 h
yield (%)
a
Key: (a) TMSOTf, MeCN, 25 °C, 1 h, 65%; (b) O2, sunlight,
entry
solvent
6
6′
t-BuOH-CHCl3 (1:3), rt, 12 h, 57% of 6 and 13% of 6′.
1
2
3
4
5
6
7
8
MeOH
EtOH
i-PrOH
t-BuOH
t-BuOH-hexane (1:1)
t-BuOH-PhH (1:1)
t-BuOH-CHCl3 (1:1)
t-BuOH-CHCl3 (1:3)
7
12
17
17
22
13
15
14
13
19
30
52
41
51
52
57
protected D-olivose (8) was realized by the method that
was recently developed in our laboratories.8 Thus, the
reaction of 14 (2.0 equiv) and 8 (1.0 equiv) in the presence
of TMSOTf (0.5 equiv) in MeCN at 25 °C for 1 h gave
the desired aryl â-C-glycoside 15 in 27% yield as the only
isolated product. The â-C-glycoside 15 was then deben-
zylated by hydrogenolysis using 10% Pd-C in MeOH at
25 °C for 1 h to afford the unprotected C-glycosyljuglone
6 in 78% yield. Although the desired unprotected C-
glycosyljuglone 6 was in hand, the yield of the key
reaction, that is the aryl C-glycosidation of the unpro-
tected sugar 8 was very low and not satisfactory. There-
fore, we further investigated a more effective synthesis
of the unprotected C-glycosyljuglone 6. After many at-
tempts for searching such a synthesis, we finally devel-
oped the novel two-step synthesis of the unprotected
C-glycosyljuglone 6 from the unprotected D-olivose (8) as
shown in Scheme 2. The first step was the C-glycosida-
tions of 1,5-naphthalenediol (16) with the unprotected
sugar, D-olivose (8). Thus, the C-glycosidation of 16 (2.0
equiv) and 8 (1.0 equiv) using TMSOTf (0.2 equiv) in
MeCN at 25 °C for 1 h proceeded smoothly to give the
unprotected aryl â-C-glycoside 17 in 65% yield as a single
isomer. Furthermore, it was found that the unprotected
methyl D-olivoside also coupled with 16 under similar
conditions to afford 17 in a similar yield. The second step
was the oxygenation of 17 to 6. At this stage, we first
examined the oxygenation of 17 using ammonium ceri-
um(IV) nitrate (CAN),13 potassium nitrosodisulfonate
(Fremy’s salt),14 thallium(III) nitrate trihydrate (TTN),15
and oxygen in the presence of Triton B16 as the oxygenat-
ing agents that are widely used for the conversion of
naphthol to quinone. From the results shown in Table 1,
however, the desired C-glycosyljuglone 6 was not detected
at all or isolated in a very low yield while the regioisomer
6′ was predominantly produced in some cases. Therefore,
our attention next turned to the photooxygenation17 of
17. These results are summarized in Table 2. Remark-
ably, the regioselectivity of the oxygenation of 17 dra-
matically changed, and the desired C-glycosyljuglone 6
was predominantly obtained by choice of the appropriate
reaction solvent. Thus, the photooxygenation of 17 with-
out any reagent was best effected by the irradiation of
sunlight in t-BuOH-CHCl3 (1:3, 0.0069 M for 17) under
an oxygen atmosphere at room temperature for 12 h to
give the desired unprotected C-glycosyljuglone 6 in 57%
yield along with a 13% yield of 6′ (entry 8 in Table 2).
Thus, the short step and effective synthesis of the
Sch em e 3a
a
Key: (a) ref 18; (b) LDA, Tf2NPh, THF, -78 f 25 °C, 1 h,
94%; (c) (Ph3P)4Pd, LiCl, DMF, 70 °C, 1 h, 93%; (d) AD-mix-â,
t-BuOH-H2O, 0 °C, 12 h, 92%; (e) NaIO4, THF-H2O, 25 °C, 1.5
h, 87%; (f) THF, 25 °C, 0.5 h, 77%.
C-glycosyljuglone 6 without any protecting group both
in the aglycon and in the glycon moieties was achieved.
Syn th esis of th e Dien e 7. With the unprotected
C-glycosyljuglone 6 as a dienophile for the Diels-Alder
reaction in hand, our attention next turned to the
preparation of an appropriate diene (Scheme 3). For this
purpose, cyclohexanone 19,18 which was obtained using
3-methyl-2-cyclohexen-1-one (9) and the silylcuprate 18,
was selected as the starting material. The cyclohexanone
19 had a phenyldimethylsilyl group as the masked form
of a hydroxyl group.9 Regioselective enolate formation of
19 with lithium diisopropylamide (LDA) and trapping of
(13) Sibi, M. P.; Dankwardt, J . W.; Snieckus, V. J . Org. Chem. 1986,
51, 271.
(14) Teuber, H.-J .; Go¨tz, N. Chem. Ber. 1954, 87, 1236.
(15) Crouse, D. J .; Wheeler, M. M.; Goemann, M.; Tobin, P. S.; Basu,
S. K.; Wheeler, D. M. S. J . Org. Chem. 1981, 46, 1814.
(16) Yamaguchi, M.; Hasebe, K.; Higashi, H.; Uchida, M.; Irie, A.;
Minami, T. J . Org. Chem. 1978, 43, 3649.
(17) Pfoertner, K.; Bo¨se, D. Helv. Chim. Acta 1970, 53, 1553.
(18) Ager, D. J .; Fleming, I.; Patel, S. K. J . Chem. Soc., Perkin Trans.
1 1981, 2520.

7104 J . Org. Chem., Vol. 64, No. 19, 1999
Matsuo et al.
Sch em e 4a
the intermediate enolate with N-phenyltrifluoromethane-
sulfonimide (Tf2NPh) afforded only the desired regioiso-
mer of the vinyl triflate 20 in 94% yield. The high
regioselectivity resulted from a combination of the steric
shielding arisen from the methyl and silyl groups and
the â-effect of the silicon.19 The cross-coupling reaction20
of the vinyl triflate 20 and vinyltributyltin (21) using a
catalytic amount of (Ph3P)4Pd and LiCl in DMF at 70 °C
for 1 h yielded the diene 22 in 93% yield. At this stage,
we tried the regioselective dihydroxylation of the exo
double bond in 22 using several reagents. It was finally
found that the dihydroxylation by Sharpless AD reac-
tion21 using a bulky AD-mix-â gave good selectivity to
afford the desired diol 23 in 92% yield, while OsO4 gave
poor selectivity and produced a significant amount of the
corresponding tetraol. The oxidative cleavage of 23 using
NaIO4 gave the R,â-unsaturated aldehyde 24 in 87%
yield. Finally, the Wittig reaction of 24 with 2.0 equiv of
triphenyl(phenylthiomethylene)phosphine (25)22 in THF
at 25 °C proceeded stereospecifically to give only the
desired E,E-diene 7 in 77% yield.
Tota l Syn th esis of 1. Following the completion of the
syntheses of dienophile 6 and diene 7, we focused on their
cycloaddition by Diels-Alder reaction and total synthesis
of 1 (Scheme 4). The Diels-Alder cycloaddition between
the unprotected C-glycosyljuglone 6 (1.0 equiv) and the
diene 7 (1.0 equiv) using B(OAc)323 followed by treatment
of the resulting Diels-Alder product by 1,8-diazabicyclo-
[5.4.0]undec-8-ene (DBU) afforded the cycloadduct 26 in
58% overall yield. The high regioselectivity came from
the coordination of B(OAc)3 between the C5 hydroxy
group and the C4 carbonyl oxygen in 6 and the electron-
donating nature of the thiophenyl group in 7. The
conversion of the silyl group into the tertiary hydroxyl
group was achieved using Fleming’s method9,24 in two
steps. Thus, 26 was first treated with HBF4‚Et2O in CH2-
Cl2 at 25 °C for 2 h to afford the fluoride 27, which was
then treated with KF, KHCO3, and 31% H2O2 in THF-
MeOH at 25 °C for 14 h to give the tertiary alcohol 28 in
42% overall yield. Finally, the regioselective oxygenation
of 28 was successfully carried out by mild photooxygen-
ation,25 in which a MeOH solution of 28 was exposed to
daylight, to furnish urdamycinone B (1) (36%) and the
C3 epimer 29 (35%) after their separation by reversed-
phase preparative thin-layer chromatography.4 The faster
moving isomer was in good agreement with natural
urdamycinone B based on the 270 MHz 1H and 13C NMR,
[R]D, and mp.
a
Key: (a) B(OAc)3, CH2Cl2, 25 °C, 2 h, then DBU, CH2Cl2, 25
°C, 0.5 h, 58%; (b) HBF4‚Et2O, CH2Cl2, 25 °C, 2 h, 78%; (c) KF,
KHCO3, 31% H2O2, THF-MeOH, 25 °C, 14 h, 53%; (d) O2,
sunlight, MeOH, 25 °C, 24 h, 71%, then separation, 36% for 1,
35% for 29.
novel approach would provide a significant new entry for
the synthesis of the C-glycosylangucycline family of
antibiotics, which is a large group of biologically active
secondary metabolites of microbial origin.
Exp er im en ta l Section
Gen er a l Meth od s. Melting points are uncorrected. 1H
NMR spectra were measured in CDCl3 using TMS as internal
standard unless otherwise noted. High-resolution mass spectra
(HRMS) were recorded under electron impact (EI) conditions.
Silica gel TLC and column chromatography were performed
on Merck TLC 60F-254 (0.25 mm) and Fuji-Davison BW-
820MH or BW-300, respectively. Air- and/or moisture-sensitive
reactions were carried out under an atomosphere of argon with
oven-dried glassware. In general, organic solvents were puri-
fied and dried by the appropriate procedure, and evaporation
and concentration were carried out under reduced pressure
below 30 °C, unless otherwise noted.
Na p h th oqu in on e 11. To a stirred solution of 10 (5.15 g,
29.6 mmol) and methoxymethyl chloride (8.9 mL, 118 mmol)
in dry CH2Cl2 (155 mL) at 0 °C was added i-Pr2NEt (15.5 mL,
88.7 mmol). After 1 h of stirring at 0 °C and 0.5 h of stirring
at 25 °C, saturated aqueous NH4Cl (150 mL) was added slowly
to the reaction mixture under ice-cooling, and the resultant
mixture was then extracted with diethyl ether. The extracts
were washed with saturated aqueous NaCl, dried over anhy-
drous Na2SO4, and concentrated in vacuo. Purification of the
residue by flash column chromatography (600 g of silica gel,
2:1 n-hexane-ethyl acetate) gave 11 (5.95 g, 92%) as an orange
solid: Rf 0.32 (2:1 n-hexane-ethyl acetate); mp 102.5-103.0
Con clu sion s
The present work demonstrates the total synthesis of
C-glycosylangucycline, urdamycinone B (1), by a novel
strategy that includes the higly stereoselective aryl
C-glycosidation of the unprotected sugar 8 and the highly
regioselective Diels-Alder reaction of the unprotected
C-glycosyljuglone 6 and the diene 7 as the key steps. This
1
°C (n-hexane, needles); H NMR δ 3.55 (3H, s), 5.36 (2H, s),
6.86 (1H, d, J ) 10.2 Hz), 6.91 (1H, d, J ) 10.2 Hz), 7.54 (1H,
dd, J ) 8.0, 1.8 Hz), 7.67 (1H, dd, J ) 8.0, 8.0 Hz), 7.80 (1H,
dd, J ) 8.0, 1.8 Hz). Anal. Calcd for C12H10O4: C, 66.05; H,
4.62. Found: C, 66.09; H, 4.57.
Na p h th a len e 13. To a stirred solution of 11 (5.95 g, 27.3
mmol) in ethyl acetate (179 mL) was added a catalytic amount
of 10% Pd-C. After the reaction mixture was vigorously stirred
at 25 °C for 1 h under H2, the mixture was filtered, and the
catalytst was washed with ethyl acetate. The combined filtrate
and washings were concentrated in vacuo. To an ice-cold
solution of the residue in dry DMF (180 mL) were added benzyl
bromide (9.7 mL, 68.2 mmol) and NaH (60% in mineral oil,
3.71 g, 92.8 mmol). After the reaction mixture was stirred at
25 °C for 1 h, ethanol (100 mL) and saturated aqueous NH4Cl
(200 mL) were added slowly to the reaction mixture under ice-
(19) Krohn, K.; Khanbabaee, K.; Micheel, J . Liebigs Ann. Chem.
1995, 1529.
(20) Scott, W. J .; Crisp, G. T.; Stille, J . K. J . Am. Chem. Soc. 1984,
106, 4630.
(21) Kolb, H. C.; VanNieuwenhze, M. S.; Sharpless, K. B. Chem.
Rev. 1994, 94, 2483.
(22) Guingant, A.; Barreto, M. M. Tetrahedron Lett. 1987, 28, 3107.
(23) Kelly, T. R.; Montury, M. Tetrahedron Lett. 1978, 19, 4309.
(24) Chan, T. H.; Nwe, K. T. J . Org. Chem. 1992, 57, 6107.
(25) Krohn, K.; Ballwanz, C. R.; Baltus, W. Liebigs. Ann. Chem.
1993, 911.

Total Synthesis of C-Glycosylangucycline
J . Org. Chem., Vol. 64, No. 19, 1999 7105
cooling, and the resultant mixture was then extracted with
diethyl ether. The extracts were washed with saturated
aqueous NaCl, dried over anhydrous Na2SO4, and concentrated
in vacuo. Purification of the residue by flash column chroma-
tography (600 g of silica gel, 8:1 n-hexane-ethyl acetate) gave
13 (9.39 g, 86%) as a white solid: Rf 0.65 (3:1 n-hexane-ethyl
acetate); mp 110.5-111.0 °C (n-hexane, cubes); 1H NMR δ 3.47
(3H, s), 5.12 (2H, s), 5.19 (4H, s), 6.78 (1H, d, J ) 8.4 Hz),
6.84 (1H, d, J ) 8.4 Hz), 7.17 (1H, dd, J ) 8.0, 1.2 Hz), 7.3-
7.6 (11H, m), 8.07 (1H, dd, J ) 8.0, 1.2 Hz). Anal. Calcd for
cubes); 1H NMR δ 1.42 (3H, d, J ) 6.4 Hz), 1.47 (1H, ddd, J )
12.2, 11.2, 11.2 Hz), 2.50 (1H, ddd, J ) 12.2, 5.2 and 2.0 Hz),
3.21 (1H, dd, J ) 9.0, 9.0 Hz), 3.52 (1H, dq, J ) 9.8, 6.4 Hz),
3.85 (1H, ddd, J ) 11.2, 9.8, 5.2 Hz), 4.92 (1H, dd, J ) 11.2,
2.0 Hz), 6.94 (2H, s), 7.64 (1H, d, J ) 8.0 Hz), 7.83 (1H, d, J
) 8.0 Hz), 12.31 (1H, s). Anal. Calcd for C16H16O6: C, 63.15;
H, 5.30. Found: C, 63.15; H, 5.49. 6′: Rf 0.50 (3:2 n-hexane-
acetone); [R]23D +140.7 ° (c 0.027, CHCl3); 1H NMR δ 1.38 (1H,
ddd, J ) 12.2, 10.8, 10.8 Hz), 1.39 (3H, d, J ) 6.0 Hz), 2.46
(1H, ddd, J ) 12.2, 5.2 and 2.0 Hz), 3.16 (1H, dd, J ) 9.2, 9.2
Hz), 3.48 (1H, dq, J ) 9.2, 6.0 Hz), 3.83 (1H, ddd, J ) 10.8,
9.2, 5.2 Hz), 4.66 (1H, ddd, J ) 10.8, 2.0, 1.4 Hz), 7.08 (1H, d,
J ) 1.4 Hz), 7.27 (1H, dd, J ) 5.4, 5.4 Hz), 7.62 (2H, d, J )
5.4 Hz), 11.97 (1H, s). Anal. Calcd for C16H16O6: C, 63.15; H,
5.30. Found: C, 63.24; H, 5.56.
C
26H24O4: C, 77.98; H, 6.04. Found: C, 77.86; H, 5.91.
Na p h th ol 14. To an ice-cold solution of 13 (6.23 g, 15.6
mmol) in dry CH2Cl2 (187 mL) was added trifluoroacetic acid
(1.44 mL, 18.7 mmol) with stirring. After the reaction mixture
was stirred at 25 °C for 1 h, the mixture was concentrated in
vacuo. Purification of the residue by flash column chromatog-
raphy (550 g of silica gel, 10:1 n-hexane-ethyl acetate) gave
14 (4.71 g, 85%) as a white solid: Rf 0.42 (5:1 n-hexane-ethyl
Vin yl Tr ifla te 20. To a stirred solution of lithium diiso-
propylamide (LDA) (18.6 mmol) in dry THF (46 mL) at -78
°C was added dropwise a solution of 1918 (4.59 g, 18.6 mmol)
in dry THF (23.0 mL). After the reaction mixture was stirred
at -78 °C for 0.5 h, N-phenyltrifluoromethanesulfonimide (Tf2-
NPh) (7.32 g, 20.5 mmol) was added to the reaction mixture
at -78 °C. The resulting solution was then stirred at -78 °C
for 0.5 h and allowed to warm to 0 °C for 0.5 h with stirring.
The reaction was quenched with saturated aqueous NH4Cl (46
mL) under ice-cooling, and the resulting mixture was then
extracted with diethyl ether. The extracts were washed with
saturated aqueous NaCl, dried over anhydrous Na2SO4, and
concentrated in vacuo. Purification of the residue by flash
column chromatography (210 g of silica gel, 20:1 n-hexane-
ethyl acetate) gave 20 (6.60 g, 94%) as a colorless oil: Rf 0.53
1
acetate); mp 108.5-109.5 °C (n-hexane, needles); H NMR δ
5.19 (2H, s), 5.23 (2H, s), 6.70 (1H, d, J ) 8.4 Hz), 6.75 (1H, d,
J ) 8.4 Hz), 6.91 (1H, dd, J ) 8.0, 1.2 Hz), 7.3-7.6 (11H, m),
7.82 (1H, dd, J ) 8.0, 1.2 Hz), 9.52 (1H, s). Anal. Calcd for
C
24H20O3: C, 80.88; H, 5.66. Found: C, 80.76; H, 5.39.
C-Glycosid e 15. To a stirred mixture of D-olivose (8) (50.0
mg, 0.337 mmol) and 14 (241.0 mg, 0.676 mmol) in dry MeCN
(13 mL) was added trimethylsilyl trifluoromethanesulfonate
(40.0 µL, 0.207 mmol) dropwise at 0 °C under argon. After the
reaction mixture was stirred at 25 °C for 1 h, Et3N was added
slowly to the reaction mixture under ice-cooling, and the
resultant mixture was then concentrated in vacuo. Purification
of the residue by flash column chromatography (30 g of silica
gel, 10:1 chloroform-methanol) gave 15 (44.3 mg, 27%) as a
1
(20:1 n-hexane-ethyl acetate); H NMR δ 0.32 (6H, s), 0.96
(3H, s), 1.35-2.55 (6H, m), 5.70 (1H, m), 7.3-7.6 (5H, m);
HRMS (EI) m/z 378.0916 (378.0933 calcd for C16H21F3O3SSi,
M+).
yellow foam: Rf 0.33 (1:1 n-hexane-acetone); [R]28 +48.2° (c
D
1
0.51, MeOH); H NMR δ 1.40 (3H, d, J ) 6.0 Hz), 1.64 (1H,
ddd, J ) 13.2, 11.4, 11.4 Hz), 2.36 (1H, ddd, J ) 13.2, 5.0, 2.2
Hz), 3.22 (1H, dd, J ) 8.8, 8.8 Hz), 3.51 (1H, dq, J ) 8.8, 6.0
Hz), 3.81 (1H, ddd, J ) 11.4, 9.0, 5.0 Hz), 5.03 (1H, dd, J )
11.4, 2.2 Hz), 5.19 (2H, s), 5.21 (2H, s), 6.68 (1H, d, J ) 9.0
Hz), 6.75 (1H, d, J ) 9.0 Hz),7.3-7.55 (10H, m), 7.60 (1H, d,
J ) 8.8 Hz), 7.84 (1H, d, J ) 8.8 Hz), 9.78 (1H, s). Anal. Calcd
for C30H30O6: C, 74.06; H, 6.21. Found: C, 73.98; H, 6.43.
C-Glycosid e 17. To a stirred mixture of D-olivose (8) (85.0
mg, 0.574 mmol) and 1,5-naphthalenediol (16) (183.8 mg, 1.15
mmol) in dry MeCN (5.7 mL) was added trimethylsilyl tri-
fluoromethanesulfonate (22.0 µL, 0.115 mmol) under ice-
cooling. After being stirred for 1 h at 25 °C, the reaction was
quenched with Et3N and the resulting mixture was then
concentrated in vacuo. Purification of the residue by flash
column chromatography (25 g of silica gel, 10:1 chloroform-
methanol) gave 17 (108.8 mg, 65%) as a white solid: Rf 0.34
Dien e 22. To a stirred solution of 20 (6.60 g, 17.4 mmol) in
dry DMF (198 mL) at 25 °C were added (Ph3P)4Pd (403 mg,
0.349 mmol), LiCl (5.17 g, 122 mmol), and vinyltributyltin (21)
(5.61 mL, 19.2 mmol). After the reaction mixture was stirred
at 70 °C for 1 h under argon, the mixture was poured into
ice-cold water (200 mL), and the resulting mixture was then
extracted with diethyl ether. The extracts were washed with
saturated aqueous NaCl, dried over anhydrous Na2SO4, and
concentrated in vacuo. Purification of the residue by flash
column chromatography (225 g of silica gel, 1000:1 n-hexane-
ethyl acetate) gave 22 (4.16 g, 93%) as a colorless oil: Rf 0.67
1
(20:1 n-hexane-ethyl acetate); H NMR δ 0.32 (6H, s), 0.91
(3H, s), 1.35-2.3 (6H, m), 4.87 (1H, d, J ) 10.5 Hz), 5.03 (1H,
d, J ) 17.2 Hz), 5.72 (1H, s), 6.34 (1H, dd, J ) 17.2, 10.5 Hz),
7.3-7.6 (5H, m). Anal. Calcd for C17H24Si: C, 79.62; H, 9.43.
Found: C, 79.41; H, 9.64.
(4:1 chloroform-methanol); [R]28 +34.5° (c 1.12, MeOH); mp
Diol 23. To a stirred solution of AD-mix-â (11.25 g) in
t-BuOH-H2O (1:1, v/v, 60 mL) at 0 °C was added a solution
of 22 (2.06 g, 8.03 mmol) in t-BuOH-H2O (1:1, v/v, 20 mL).
After the reaction mixture was stirred vigorously at 0 °C for
12 h, the mixture was poured into ice-cold saturated aqueous
NH4Cl (100 mL), and the resulting mixture was then extracted
with ethyl acetate. The extracts were washed with saturated
aqueous NaCl, dried over anhydrous Na2SO4, and concentrated
in vacuo. Purification of the residue by flash column chroma-
tography (200 g of silica gel, 1:1 n-hexane-ethyl acetate) gave
23 (2.15 g, 92%) as a colorless oil: Rf 0.46 (1:2 n-hexane-ethyl
D
1
223.5-224.5 °C (acetone-n-hexane, needles); H NMR (CD3-
OD) δ 1.41 (3H, d, J ) 5.8 Hz), 1.78 (1H, ddd, J ) 11.6, 11.6,
11.0 Hz), 2.26 (1H, ddd, J ) 13.2, 5.0, 2.2 Hz), 3.10 (1H, dd, J
) 9.0, 9.0 Hz), 3.50 (1H, dq, J ) 9.2, 5.8 Hz), 3.71 (1H, ddd, J
) 11.0, 9.0, 4.4 Hz), 4.98 (1H, dd, J ) 11.6, 2.0 Hz), 6.75-7.7
(5H, m). Anal. Calcd for C16H18O5: C, 66.20; H, 6.25. Found:
C, 65.96; H, 6.25.
C-Glycosylju glon e 6. Meth od A. To a solution of 15 (136.0
mg, 0.28 mmol) in MeOH (13.6 mL) was added a catalytic
amount of 10% Pd-C. After the reaction mixture was vigor-
ously stirred at 25 °C for 1 h under H2, the mixture was
filtered, and the catalytst was washed with ethyl acetate. The
combined filtrate and washings were concentrated in vacuo.
Purification of the residue by flash column chromatography
(8.5 g of silica gel, 3:2 n-hexane-acetone) gave 6 (66.0 mg,
78%) as an orange solid. Meth od B. A solution of 17 (108.8
mg, 0.375 mmol) in t-BuOH-CHCl3 (1:3, 54.4 mL) was
irradiated with diffuse sunlight (a 75 W xenon lamp, Wacom
Sunray Lamp, I-Sunsun) under O2 for 12 h and then concen-
trated in vacuo. Purification of the residue by flash column
chromatography (23 g of silica gel, 2:1 n-hexane-acetone) gave
6 (64.4 mg, 57%) and 6′ (14.8 mg, 13%) as orange solids,
respectively. 6: Rf 0.46 (3:2 n-hexane-acetone); [R]30D +143.5°
(c 0.023, CHCl3); mp 171.5-172.5 °C (diethyl ether-n-hexane,
1
acetate); H NMR δ 0.00 (6H, s), 0.58 (3H, s), 1.0-1.95 (8H,
m), 3.1-3.4 (1H, m), 5.43 (1H, m), 7.0-7.3 (5H, m). Anal. Calcd
for C17H26O2Si: C, 70.29; H, 9.02. Found: C, 70.25; H, 9.29.
Ald eh yd e 24. To an ice-cold solution of 23 (2.15 g, 7.40
mmol) in THF-H2O (3:1, v/v, 86 mL) at 0 °C was added NaIO4
(1.58 g, 7.43 mmol) with stirring. The reaction mixture was
stirred at 25 °C for 1.5 h and then poured into ice-cooled water
(80 mL). The resultant mixture was then extracted with ethyl
acetate. The extracts were washed with saturated aqueous
NaCl, dried over anhydrous Na2SO4, and concentrated in
vacuo. Purification of the residue by flash column chromatog-
raphy (200 g of silica gel, 20:1 n-hexane-ethyl acetate) gave
24 (1.67 g, 87%) as a colorless oil: Rf 0.86 (1:2 n-hexane-ethyl
1
acetate); H NMR δ 0.30 (6H, s), 0.86 (3H, s), 1.45-2.4 (6H,

7106 J . Org. Chem., Vol. 64, No. 19, 1999
Matsuo et al.
m), 6.73 (1H, m), 7.3-7.6 (5H, m), 9.39 (1H, m); HRMS (EI)
m/z 258.1440 (258.1441 calcd for C16H22OSi, M+).
quenched with 10% aqueous Na2S2O3 (4 mL) under ice-cooling,
and the resultant mixture was then extracted with ethyl
acetate. The extracts were washed with saturated aqueous
NaCl, dried over anhydrous Na2SO4, and concentrated in
vacuo. Purification of the residue by flash column chromatog-
raphy (8 g of silica gel, 2:1 n-hexane-acetone) gave 28 (25.5
mg, 53%) as a yellow solid: Rf 0.24 (1:1 n-hexane-acetone);
1H NMR δ 1.43 (3H, d, J ) 6.0 Hz), 1.45-1.55 (1H, m), 1.55
(3H, s), 1.8-2.1 (2H, m), 2.53 (1H, ddd, J ) 13.0, 6.0, 3.0 Hz),
2.53 (1H, d, J ) 17.0 Hz), 3.00 (1H, s), 3.21 (1H, ddd, J )
10.0, 10.0, 4.0 Hz), 3.5-3.6 (3H, m), 3.8-3.95 (1H, m), 4.95
(1H, dd, J ) 11.0, 3.0 Hz), 7.48 (1H, d, J ) 6.4 Hz), 7.70 (1H,
d, J ) 8.0 Hz), 7.80 (1H, d, J ) 8.0 Hz), 8.17 (1H, d, J ) 6.4
Hz), 12.95 (1H, s); HRMS (EI) m/z 438.1653 (438.1679 calcd
for C25H26O7, M+).
E,E-Dien e 7. To a stirred solution of 24 (1.67 g, 6.46 mmol)
in dry THF (50 mL) at 0 °C was added 0.19 M triphenyl-
(phenylthiomethylene)phosphine (25)22/THF (68 mL, 12.9
mmol). After the reaction mixture was stirred at 25 °C for 1
h, the reaction was quenched with saturated aqueous NH4Cl
(150 mL) under ice-cooling, and the resultant mixture was then
extracted with diethyl ether. The extracts were washed with
saturated aqueous NaCl, dried over anhydrous Na2SO4, and
concentrated in vacuo. Purification of the residue by flash
column chromatography (120 g of silica gel, n-hexane) gave 7
(1.81 g, 77%) as a colorless oil: Rf 0.64 (10:1 n-hexane-ethyl
acetate); 1H NMR δ 0.33 (6H, s), 0.92 (3H, s), 1.1-2.4 (6H,
m), 5.72 (1H, m), 6.18 (1H, d, J ) 15.2 Hz), 6.44 (1H, d, J )
15.2 Hz), 7.1-7.7 (10H, m), 9.39 (1H, m). Anal. Calcd for
Ur d a m ycin on e B (1). A stirred solution of 28 (9.8 mg,
0.0223 mmol) in MeOH (2.0 mL) was irradiated with diffuse
sunlight (a 75 W xenon lamp, Wacom Sunray Lamp, I-Sunsun)
under O2 for 24 h and then concentrated in vacuo. Purification
of the residue by flash column chromatography (2 g of silica
gel, 1:1 n-hexane-acetone) gave a mixture of 1 and 29 (7.2
mg, 71%). Their separation using reversed-phase preparative
thin-layer chromatography (Merk 15389-1M, RP-18 F2548, 1:3
H2O-methanol) gave 1 (3.6 mg, 36%) and 29 (3.5 mg, 35%) as
yellow solids, respectively. 1: Rf 0.32 (1:2 n-hexane-acetone);
[R]32D +50.0° (c 0.012, MeOH); [lit.5 [R]D +50° (c 0.012, MeOH)];
[R]32 +25.00° (c 0.016, CHCl3); [lit.4 [R]32 +25° (c 0.016,
C
23H28SSi: C, 75.76; H, 7.74. Found: C, 75.50; H, 7.83.
Cycloa d d u ct 26. To a stirred solution of 6 (74.0 mg, 0.243
mmol) in dry CH2Cl2 (24 mL) at 0 °C was added B(OAc)3 (50.0
mg, 0.266 mmol). After the mixture was stirred for 0.5 h at 0
°C, a solution of 7 (98.0 mg, 0.269 mmol) in dry CH2Cl2 (2 mL)
was added to the reaction mixture at 0 °C. After the resultant
mixture was stirred at 25 °C for 1.5 h, ice-cooled saturated
aqueous NaHCO3 (12 mL) was added to the reaction mixture,
and the resulting mixture was then extracted with diethyl
ether. The extracts were washed with saturated aqueous NaCl,
dried over anhydrous Na2SO4, and concentrated in vacuo. To
a solution of the residue in dry CH2Cl2 (2 mL) at 0 °C was
added 1,8-diazabicyclo[5.4.0]undec-8-ene (DBU) (80.0 µL, 0.535
mmol). After the reaction mixture was stirred at 0 °C for 0.5
h, ice-cooled saturated aqueous NH4Cl (8 mL) was added to
the reaction mixture, and the resulting mixture was then
extracted with ethyl acetate. The extracts were washed with
saturated aqueous NaCl, dried over anhydrous Na2SO4, and
concentrated in vacuo. Purification of the residue by flash
column chromatography (14 g of silica gel, 3:2 n-hexane-
acetone) gave 26 (78.5 mg, 58%) as a yellow solid: Rf 0.31 (3:2
n-hexane-acetone); 1H NMR δ 0.34 (3H, s), 0.35 (3H, s), 0.96
(3H, s), 1.42 (3H, d, J ) 6.0 Hz), 1.4-1.6 (1H, m), 1.75 (2H,
dd, J ) 8.2, 5.2 Hz), 2.45-2.6 (1H, m), 2.53 (1H, d, J ) 16.1
Hz), 3.01 (1H, d, J ) 16.1 Hz), 3.15-3.5 (1H, m), 3.22 (1H, dd,
J ) 9.2, 9.2 Hz), 3.53 (1H, dq, J ) 9.2, 6.0 Hz), 3.86 (1H, m),
4.94 (1H, dd, J ) 11.2, 1.8 Hz), 7.3-7.6 (5H, m), 7.43 (1H, d,
J ) 8.0 Hz), 7.74 (1H, d, J ) 8.0 Hz), 7.87 (1H, d, J ) 8.0 Hz),
8.11 (1H, d, J ) 8.0 Hz), 12.97 (1H, s). Anal. Calcd for C33H36O6-
Si: C, 71.19; H, 6.52. Found: C, 70.92; H, 6.54.
D
D
CHCl3)]; mp 239.5-240.5 °C dec (lit.4 mp 240 °C dec); 1H NMR
(acetone-d6) δ 1.36 (3H, d, J ) 6.4 Hz), 1.41 (1H, ddd, J )
12.6, 11.2, 11.2 Hz), 1.49 (3H, s), 2.44 (1H, ddd, J ) 12.6, 5.0,
2.0 Hz), 2.88 (1H, dd, J ) 14.5, 2.0 Hz), 3.08 (1H, d, J ) 14.5
Hz), 3.09 (1H, ddd, J ) 9.2, 9.2, 2.2 Hz), 3.21 (1H, dd, J )
16.8, 1.4 Hz), 3.32 (1H, d, J ) 16.8 Hz), 3.48 (1H, dq, J ) 9.2,
6.4 Hz), 3.74 (1H, dddd, J ) 11.2, 9.2, 5.0, 2.2 Hz), 4.92 (1H,
dd, J ) 11.2, 2.0 Hz), 7.61 (1H, d, J ) 8.0 Hz), 7.73 (1H, d, J
) 8.0 Hz), 7.94 (1H, d, J ) 8.0 Hz), 8.31 (1H, d, J ) 8.0 Hz),
12.71 (1H, s); 13C NMR (acetone-d6) δ 18.7, 40.9, 44.7, 54.2,
71.9, 72.6, 73.5, 77.2, 78.7, 115.9, 119.4, 129.5, 134.1 (2), 134.4,
134.8, 135.1, 137.1, 138.1, 150.1, 158.9, 183.4, 189.1, 196.9;
HRMS (EI) m/z 453.1562 (453.1549 calcd for C25H24O8, M +
H+). 29: Rf 0.31 (1:2 n-hexane-acetone); [R]32 +150.00° (c
D
0.023, CHCl3); [lit.4 [R]D +150° (c 0.023, CHCl3)]; mp 289.0-
289.5 °C dec; (lit.4 mp 290 °C dec); 1H NMR (acetone-d6) δ 1.36
(3H, d, J ) 6.4 Hz), 1.41 (1H, ddd, J ) 12.6, 11.2, 11.2 Hz),
1.49 (3H, s), 2.44 (1H, ddd, J ) 12.6, 5.0, 2.0 Hz), 2.88 (1H,
dd, J ) 14.5, 2.0 Hz), 3.08 (1H, d, J ) 14.5 Hz), 3.09 (1H, ddd,
J ) 9.2, 9.2, 2.2 Hz), 3.21 (1H, dd, J ) 16.8, 1.4 Hz), 3.32 (1H,
d, J ) 16.8 Hz), 3.48 (1H, dq, J ) 9.2, 6.4 Hz), 3.74 (1H, dddd,
J ) 11.2, 9.2, 5.0, 2.2 Hz), 4.92 (1H, dd, J ) 11.2, 2.0 Hz),
7.61 (1H, d, J ) 8.0 Hz), 7.73 (1H, d, J ) 8.0 Hz), 7.94 (1H, d,
J ) 8.0 Hz), 8.31 (1H, d, J ) 8.0 Hz), 12.71 (1H, s); HRMS
(EI) m/z 453.1526 (453.1549 calcd for C25H24O8, M + H+).
F lu or id e 27. To an ice-cold solution of 26 (78.5 mg, 0.141
mmol) in dry CH2Cl2 (3.1 mL) was added HBF4‚Et2O (488 µL,
2.82 mmol). After the reaction mixture was stirred at 25 °C
for 2 h, the reaction was quenched with saturated aqueous
NaHCO3 (3 mL) under ice-cooling, and the resultant mixture
was then extracted with diethyl ether. The extracts were
washed with saturated aqueous NaCl, dried over anhydrous
Na2SO4, and concentrated in vacuo. Purification of the residue
by flash column chromatography (7 g of silica gel, 2:1 n-hex-
ane-acetone) gave 27 (54.8 mg, 78%) as a yellow solid: Rf 0.50
Ack n ow led gm en t. We sincerely thank Professor
Masahiko Yamaguchi (Tohoku University) for his help-
ful advice on differentiation and identification of urda-
mycinone B and its C3 epimer. We are also deeply
grateful to Professor Gary A. Sulikowski (Texas A&M
University) for kindly providing spectral data of urda-
mycinone B. We are indebted to Mr. K. Hokazono of
Keio University for elemental analyses. Financial sup-
port by The Nissan Science Foundation is gratefully
acknowledged.
1
(1:1 n-hexane-acetone); H NMR δ 0.23 (3H, s), 0.26 (3H, s),
1.03 (3H, s), 1.42 (3H, d, J ) 6.4 Hz), 1.4-1.6 (1H, m), 1.65-
2.0 (2H, m), 2.53 (1H, ddd, J ) 12.4, 5.2, 1.8 Hz), 2.63 (1H, d,
J ) 17.0 Hz), 3.11 (1H, d, J ) 17.0 Hz), 3.22 (1H, ddd, J )
9.0, 9.0, 4.0 Hz), 3.54 (1H, dq, J ) 9.0, 6.4 Hz), 3.50 (2H, m),
3.86 (1H, m), 4.95 (1H, dd, J ) 11.2, 1.8 Hz), 7.50 (1H, d, J )
8.0 Hz), 7.77 (1H, d, J ) 8.0 Hz), 7.89 (1H, d, J ) 8.0 Hz),
8.17 (1H, d, J ) 8.0 Hz), 12.96 (1H, s); HRMS (EI) m/z 498.1866
(498.1873 calcd for C27H31O6FSi, M+).
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra for
compounds 20, 24, 27, 28, 1, and 29. This material is available
free of charge via the Internet at http://pubs.acs.org.
Alcoh ol 28. To a solution of 27 (46.0 mg, 0.0922 mmol) in
THF-MeOH (1:1, 3.7 mL) were added KF (16.1 mg, 0.277
mmol), KHCO3 (27.7 mg, 0.277 mmol), and 31% H2O2 (aq) (91.1
µL, 0.830 mmol) under ice-cooling. After the reaction mixture
was stirred at 25 °C for 19 h, the reaction mixture was
J O990648Y