Hz, 3H), 1.051.06 (m, 21H), 1.12 (d, J = 6.8 Hz, 3H), 1.53
Allyl {2-[(3S,4S,5S,6R)-7-Hydroxy-4,6-dimethoxy-3,5-di-
methylheptyl]-5,7-dimethoxy-3-methyl-4-oxo-4H-chromen-
8-yl} Carbonate (35b). Under argon, with stirring, HOAc
1
1
6
5
1
6
1
.65 (m, 1H), 1.731.89 (m, 3H), 1.99 (s, 3H), 2.522.62 (m,
H), 2.712.80 (m, 1H), 3.03 (dd, J = 2.5, 9.1 Hz, 1H), 3.48 (s,
H), 3.533.57 (m, 1H), 3.603.66 (m, 4H), 3.833,96 (m, 7H),
(0.2 mL, 3.51 mmol) was added to 1 M (in THF) TBAF¢3H O
2
.09 (s, 2H), 6.39 (s, 1H); 13C NMR (CDCl ): ¤ 9.7, 10.3, 11.9,
(2.81 mL, 2.81 mmol) and the resulting mixture was added with
a syringe to a degassed solution of chromone 35a (397 mg,
0.585 mmol) in THF (1 mL). After 5 d stirring at rt, the solvents
were eliminated in a vacuum and the residue was chromato-
graphed on silica gel (50:1 EtOAc/MeOH) to give the chro-
3
7.8, 18.0, 27.7, 30.1, 34.8, 37.4, 56.1, 56.4, 57.2, 58.7, 61.3,
5.9, 80.9, 87.4, 92.1, 98.7, 108.1, 117.0, 126.7, 151.8, 155.8,
56.6, 162.6, 177.3; Anal. Found: C, 63.49; H, 9.03%. Calcd
for C H O Si: C, 63.92; H, 9.15%.
3
4
58
9
2
-[(3S,4S,5S,6R)-4,6-Dimethoxy-3,5-dimethyl-7-{(triiso-
propylsilyl)oxy}heptyl]-8-hydroxy-5,7-dimethoxy-3-methyl-
H-chromen-4-one (34). In a flask connected to an argon/
mone 35b as a thick colorless oil (306 mg; 100%). [α] =
D
¹3.4 (c 1, EtOAc); TLC (EtOAc: MeOH = 50:1) R = 0.24;
f
1
4
H NMR (CDCl ): ¤ 0.74 (d, J = 7.0 Hz, 3H), 1.09 (d, J = 6.8
3
vacuum line, a solution of chromone 6c (440 mg, 0.69 mmol) in
CH Cl (15 mL) was thoroughly degassed, and then cooled to
Hz, 3H), 1.491.57 (m, 1H), 1.681.90 (m, 3H), 1.98 (s, 3H),
2.07 (br s, 1H, OH), 2.532.63 (m, 1H), 2.672.77 (m, 1H),
2.98 (dd, J = 3.4, 8.3 Hz, 1H), 3.443.49 (m, 7H), 3.65 (m,
2H), 3.95 (s, 3H), 3.97 (s, 3H), 4.76 (d, J = 5.7 Hz, 2H), 5.33
(d, J = 10.5 Hz, 1H), 5.44 (d, J = 17.2 Hz, 1H), 6.00 (ddt,
J = 5.7, 10.5, 17.2 Hz, 1H), 6.39 (s, 1H); C NMR (CDCl3):
¤ 9.7, 11.4, 17.7, 27.6, 29.6, 34.6, 37.7, 56.3, 56.5, 58.4, 61.3,
62.9, 69.6, 81.2, 87.9, 91.5, 107.6, 117.5, 119.3, 121.1, 131.1,
150.5, 152.9, 154.7, 158.4, 162.2, 176.7; Anal. Found: C,
2
2
ca. ¹5 °C (ice/brine bath). With stirring, freshly distilled TiCl4
0.23 mL, 2.07 mmol) was added with a syringe. A red-brown
(
color immediately developed and, 10 min later, when TLC
analysis showed the reaction was complete, cold 10% NaHCO3
1
3
(35 mL) was rapidly added, the stirring being continued at 0 °C
until discoloration (ca. 510 min). The aqueous phase was
extracted CH Cl (3 © 50 mL) and the pooled organic extracts
2
2
were washed with brine (2 © 50 mL), and dried (Na SO ).
61.87; H, 7.67%. Calcd for C H O : C, 62.05; H, 7.33%.
2
4
27 38 10
Evaporation of the solvents, followed by drying of the residue
Allyl
{2-[(3S,4S,5S,6R)-4,6-Dimethoxy-3,5-dimethyl-7-
in a vacuum, afforded the hydroxychromone 34 as a pale-
oxoheptyl]-5,7-dimethoxy-3-methyl-4-oxo-4H-chromen-8-
yl} Carbonate (36). Using the conditions described above
for the oxidation of 14d to 13, DMSO (0.123 mL, 1.61 mmol)
in CH Cl (3.5 mL) was treated at ¹78 °C with oxalyl chloride
1
yellow oil (410 mg; 100%). TLC (EtOAc) R = 0.26; H NMR
f
(
CDCl ): ¤ 0.77 (d, J = 7.0 Hz, 3H), 1.041.05 (m, 21H), 1.11
3
(d, J = 6.8 Hz, 3H), 1.481.99 (m, 7H), 2.592.70 (m, 1H),
2
2
2
.762.85 (m, 1H), 3.04 (dd, J = 3.5, 8.2 Hz, 1H), 3.433.54
(0.13 mL, 1.43 mmol) before adding chromone 35b (350 mg,
0.67 mmol) diluted with CH Cl (4.5 mL), followed by DIPEA
(m, 7H), 3.62 (dd, J = 5.9, 10.3 Hz, 1H), 3.80 (dd, J = 6.0,
2
2
1
6
2
9
0.0 Hz, 1H), 3.93 (s, 3H), 4.00 (s, 3H), 5.84 (br s, 1H, OH),
(0.592 mL, 3.42 mmol). After 30 min stirring at ¹78 °C, the
reaction mixture was diluted with ether (15 mL) and poured
into iced brine (15 mL) and ether (15 mL) with vigorous
stirring. The aqueous phase was extracted with ether (4 © 15
1
3
.43 (s, 1H); C NMR (CDCl3): ¤ 9.7, 10.5, 11.9, 17.6, 17.9,
7.5, 29.7, 34.9, 37.2, 56.4, 56.8, 58.6, 61.2, 64.5, 80.9, 87.7,
2.4, 108.0, 116.9, 127.3, 145.9, 149.2, 153.0, 162.4, 177.4.
N. B. Monitoring the reaction by TLC was essential to avoid
mL). The pooled extracts were washed with 10% NH Cl (2 ©
4
the cleavage of the silyl ether. Owing to sensitivity on silica
gel, this crude product was used immediately for the next step.
Allyl {2-[(3S,4S,5S,6R)-4,6-Dimethoxy-3,5-dimethyl-7-
15 mL), brine (3 © 15 mL), and dried (Na SO ). Elimination of
the solvents in a vacuum then afforded the aldehyde 36 as a
2
4
smelly yellow oil (346 mg; 100%). TLC (EtOAc) R = 0.34;
f
1
«
(triisopropylsilyl)oxy«heptyl]-5,7-dimethoxy-3-methyl-4-
H NMR (CDCl ): ¤ 0.74 (d, J = 7.0 Hz, 3H), 1.12 (d, J =
3
oxo-4H-chromen-8-yl} Carbonate (35a). Under argon,
6.8 Hz, 3H), 1.501.88 (m, 3H), 1.98 (s, 3H), 2.072.20 (m,
1H), 2.532.63 (m, 1H), 2.692.79 (m, 1H), 3.01 (dd, J = 2.4,
9.5 Hz, 1H), 3.40 (s, 3H), 3.43 (s, 3H), 3.78 (dd, J = 1.3,
3.4 Hz, 1H), 3.95 (s, 3H), 3.97 (s, 3H), 4.76 (d, J = 5.6 Hz,
2H), 5.33 (d, J = 10.5 Hz, 1H), 5.44 (d, J = 17.2 Hz, 1H), 6.00
(ddt, J = 5.6, 10.5, 17.2 Hz, 1H), 6.40 (s, 1H), 9.57 (d, J =
Alloc-OBT (420 mg, 2.07 mmol) and DMAP (84 mg, 0.69
mmol) were added to a solution of chromone 34 (409 mg, 0.69
mmol) in CH Cl (3.5 mL). After 15 h stirring at rt, the reaction
2
2
mixture was evaporated to dryness in a vacuum and the residue
was chromatographed on silica gel (EtOAc) to give the car-
1
3
bonate 35a as a thick colorless oil (400 mg; 85%). [α] = +3.1
1.3 Hz, 1H); C NMR (CDCl ): ¤ 9.7, 11.6, 17.5, 27.1, 29.5,
D
3
1
(
c 1, CH Cl ); TLC (EtOAc) R = 0.51; H NMR (CDCl ): ¤
34.3, 37.3, 56.3, 56.5, 58.3, 61.0, 69.5, 86.7, 86.9, 91.6, 107.6,
117.5, 119.2, 121.2, 131.1, 150.5, 152.9, 154.8, 158.4, 161.9,
176.7, 202.6.
N. B. Owing to sensitivity on silica gel, this product was
used for the next step without purification.
2
2
f
3
0.72 (d, J = 7.2 Hz, 3H), 1.051.06 (m, 21H), 1.10 (d, J =
6.6 Hz, 3H), 1.531.65 (m, 1H), 1.691.83 (m, 3H), 1.97 (s,
3H), 2.502.62 (m, 1H), 2.662.77 (m, 1H), 3.02 (dd, J = 2.3,
9.0 Hz, 1H), 3.47 (s, 3H), 3.48 (s, 3H), 3.533.58 (m, 1H), 3.63
(
3
dd, J = 5.5, 10.0 Hz, 1H), 3.86 (dd, J = 6.3, 10.0 Hz, 1H),
.96 (s, 3H), 3.97 (s, 3H), 4.76 (d, J = 5.6 Hz, 2H), 5.33 (d,
Allyl {2-[(3S,4S,5S,6S,7E,9E,11E)-4,6-Dimethoxy-3,5,11-
trimethyltrideca-7,9,11-trien-1-yl]-5,7-dimethoxy-3-methyl-
4-oxo-4H-chromen-8-yl} Carbonate (37). In a flask con-
nected to an argon/vacuum line, 1.56 M (in hexane) BuLi (0.49
mL, 0.76 mmol) was added with a syringe to a cooled (ice bath)
degassed solution of di-i-propylamine (97 mL, 0.69 mmol) in
THF (9.9 mL). After 30 min stirring at 0 °C, the flask was
immersed in a dry ice/acetone bath and a degassed solution
of phosphonate 9a (0.160 g, 0.69 mmol) in THF (9.9 mL) was
J = 10.5 Hz, 1H), 5.44 (d, J = 17.1 Hz, 1H), 6.01 (ddt, J = 5.5,
1
1
6
1
0.5, 17.1 Hz, 1H), 6.40 (s, 1H); 13C NMR (CDCl ): ¤ 9.6,
3
0.3, 11.9, 17.6, 18.0, 27.5, 29.8, 34.7, 37.4, 56.3, 56.5, 58.7,
1.2, 65.0, 69.5, 81.0, 87.4, 91.6, 107.7, 117.3, 119.1, 121.2,
31.2, 150.6, 152.9, 154.7, 158.4, 162.5, 176.8; Anal. Found:
C, 63.31; H, 8.81%. Calcd for C H O Si: C, 63.69; H,
8
36
58 10
.61%.
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