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T. Goto et al. / Tetrahedron 71 (2015) 8320e8332
of TBS), 0.10 (6H, s, CH3 of TBS ꢃ2), 0.11 (3H, s, CH3 of TBS), 0.79 (3H,
t, J¼7.3 Hz, H20), 0.89 (9H, s, t-Bu of TBS), 0.92 (9H, s, t-Bu of TBS),
1.45e1.55 (1H, m, H19a),1.58e1.70 (4H, m, H2 and H3),1.73 (1H, qd,
J¼7.4, 5.9 Hz, H19b), 2.09 (2H, dt, J¼7.3, 6.8 Hz, H4), 2.44 (3H, s, CH3
of Ts), 2.83 (1H, dd, J¼16.5, 4.6 Hz, H16a), 2.88 (2H, m, H7), 3.14 (1H,
dd, J¼15.5, 3.2 Hz, H13a), 3.22 (1H, dd, J¼15.5, 8.2 Hz, H13b), 3.35
(1H, dd, J¼16.5, 6.4 Hz, H16b), 3.80e3.89 (2H, m, acetal), 3.92e3.99
(2H, m, acetal), 4.01 (1H, m, H17), 4.42 (1H, m, H12), 4.62 (1H, m,
H18), 4.85 (1H, t, J¼5.0 Hz, H1), 5.29e5.43 (3H, m, H5, H6 and H8),
5.73 (1H, dd, J¼15.6, 6.9 Hz, H11), 5.99 (1H, dd, J¼11.4, 11.4 Hz, H9),
6.56 (1H, dd, J¼15.6, 11.4 Hz, H10), 7.31 (2H, d, J¼8.3 Hz, aromatic),
7.79 (2H, d, J¼8.3 Hz, aromatic); HRMS (ESI) calcd for
d
ꢄ4.75, ꢄ4.71, ꢄ4.6, ꢄ4.4, 10.3, 17.9, 18.2, 21.0, 21.6, 23.9, 25.7 (ꢃ3),
25.9 (ꢃ3), 26.0, 27.0, 29.1, 33.4, 36.5, 64.8 (ꢃ2), 72.3, 72.9, 86.2,104.5,
124.4, 127.5, 127.6, 127.8 (ꢃ2), 127.9, 128.1, 129.6, 129.7 (ꢃ2), 130.0,
134.3, 136.6, 144.5.
4.1.37. Tetraene 24ab. According to the synthetic procedure of
tetraene 24aa, 24ab (81.4 mg, 0.107 mmol) was synthesized from
23ab (146 mg, 0.139 mmol) in 77% yield by using n-Bu3SnH
(0.56 mL, 2.1 mmol) and N-methylmorpholine N-oxide (164 mg,
1.40 mmol) in toluene (68 mL). Purification was performed by flash
chromatography [a column consecutively packed with silica gel 8 g
and 10% (w/w) KF contained silica gel 2 g, hexane to hexane/EtOAc
C
47H68Co2O13SSi2Na 1069.2475 [MþNa]þ, found 1069.2482.
9/1]: colorless oil; [
a]
27ꢄ4.2 (c 0.85, CHCl3); IR (neat)
n
2955, 2929,
D
2857, 1921, 1599, 1471, 1463, 1366, 1258, 1189, 1177, 1075 cmꢄ1
;
1H
4.1.34. Complex 23ba. According to the synthetic procedure of
complex 23aa, 23ba (129 mg, 0.123 mmol) was synthesized from
22ba (99 mg, 0.130 mmol) in 95% yield by using Co2(CO)8 (192 mg,
0.561 mmol) in CH2Cl2 (2.8 mL). Purification was performed by
flash column chromatography on silica gel (10 g, hexane to hexane/
EtOAc 9/1): brown oil. The 1H NMR spectrum of 23ba was identical
of that of 23ab.
NMR (500 MHz, CDCl3)
d
ꢄ0.01 (3H, s, CH3 of TBS), 0.03 (3H, s, CH3
of TBS), 0.04 (3H, s, CH3 of TBS), 0.05 (3H, s, CH3 of TBS), 0.75 (3H, t,
J¼7.5 Hz, H20), 0.84 (9H, s, t-Bu of TBS), 0.90 (9H, s, t-Bu of TBS),
1.45e1.55 (3H, m, H3 and H19a), 1.63e1.70 (2H, m, H2), 1.77 (1H, m,
H19b), 1.98e2.30 (6H, m, H4, H13 and H16), 2.44 (3H, s, CH3 of Ts),
2.91 (2H, t, J¼6.3 Hz, H7), 3.78 (1H, ddd, J¼8.6, 4.0, 4.0 Hz, H17),
3.82e3.86 (2H, m, acetal), 3.92e3.99 (2H, m, acetal), 4.18 (1H, dt,
J¼6.9, 5.8 Hz, H12), 4.31 (1H, dt, J¼8.6, 4.0 Hz, H18), 4.85 (1H, t,
J¼4.5 Hz, H1), 5.31e5.48 (5H, m, H5, H6, H8, H14 and H15), 5.64
(1H, dd, J¼14.9, 5.8 Hz, H11), 5.97 (1H, dd, J¼10.9, 10.9 Hz, H9), 6.46
(1H, dd, J¼14.9, 10.9 Hz, H10), 7.33 (2H, d, J¼8.0 Hz, aromatic), 7.79
4.1.35. Complex 23bb. According to the synthetic procedure of
complex 23aa, 23bb (118 mg, 0.113 mmol) was synthesized from
22bb (96 mg, 0.13 mmol) in 87% yield by using Co2(CO)8 (185 mg,
0.541 mmol) in CH2Cl2 (2.5 mL). Purification was performed by flash
column chromatography on silica gel (10 g, hexane/EtOAc 20/1 to 9/
(2H, d, J¼8.0 Hz, aromatic); 13C NMR (125 MHz, CDCl3)
d
ꢄ4.75,
ꢄ4.71, ꢄ4.6, ꢄ4.4, 10.3, 17.8, 18.2, 21.0, 21.6, 23.9, 25.7 (ꢃ3), 25.9
(ꢃ3), 26.0, 27.0, 29.2, 33.4, 36.5, 64.8 (ꢃ2), 72.2, 72.7, 86.2, 104.5,
124.3, 127.5, 127.6, 127.8 (ꢃ2), 127.9, 128.1, 129.6, 129.7 (ꢃ2), 130.0,
134.3, 136.6, 144.5; HRMS (ESI) calcd for C41H70O7SSi2Na 785.4273
[MþNa]þ, found 783.4254.
1): brown oil; 1H NMR (500 MHz, CDCl3)
d 0.08 (3H, s, CH3 of TBS),
0.09 (3H, s, CH3 of TBS), 0.10 (6H, s, CH3 of TBS ꢃ2), 0.79 (3H, t,
J¼7.5 Hz, H20), 0.89 (9H, s, t-Bu of TBS), 0.92 (9H, s, t-Bu of TBS),1.49
(2H, dq, J¼7.5, 7.5 Hz, H19), 1.57e1.77 (4H, m, H2 and H3), 2.08 (2H,
dt, J¼7.4, 7.4 Hz, H4), 2.44 (3H, s, CH3 of Ts), 2.80e2.92 (3H, m, H7 and
H16a), 3.12 (1H, dd, J¼16.0, 8.6 Hz, H13a), 3.28 (1H, dd, J¼16.0, 2.9 Hz,
H13b), 3.37 (1H, dd, J¼16.6, 6.9 Hz, H16b), 3.80e3.86 (2H, m, acetal),
3.90e3.96 (2H, m, acetal), 3.97 (1H, m, H17), 4.44 (1H, m, H12), 4.62
(1H, m, H18), 4.85 (1H, t, J¼4.6 Hz, H1), 5.30e5.42 (3H, m, H5, H6 and
H8), 5.74 (1H, dd, J¼15.5, 6.9 Hz, H11), 5.97 (1H, dd, J¼11.5, 11.5 Hz,
H9), 6.58 (1H, dd, J¼15.5, 11.5 Hz, H10), 7.32 (2H, d, J¼8.6 Hz, aro-
matic), 7.79 (2H, d, J¼8.6 Hz, aromatic); HRMS (ESI) calcd for
4.1.38. Tetraene 24ba. According to the synthetic procedure of
tetraene 24aa, 24ba (45.0 mg, 59.1 mmol) was synthesized from
23ba (129 mg, 0.123 mmol) in 48% yield by using n-Bu3SnH
(0.49 mL, 1.8 mmol) and N-methylmorpholine N-oxide (141 mg,
1.21 mmol) in toluene (60 mL). Purification was performed by flash
chromatography [a column consecutively packed with silica gel 6 g
and 10% (w/w) KF contained silica gel 2 g, pentane to pentane/
C
47H68Co2O13SSi2Na 1069.2475 [MþNa]þ, found 1069.2445.
EtOAc 9/1]: colorless oil; [
lytical data of 24ba were identical to those of 24ab.
a]
23þ2.9 (c 1.2, CHCl3). The other ana-
D
4.1.36. Tetraene 24aa. n-Bu3SnH (505 mL, 1.88 mmol) and N-meth-
ylmorpholine N-oxide (146 mg,1.25 mmol) were successively added
to a solution of alkyne dicobalt hexacarbonyl complex 23aa (130 mg,
0.124 mmol) in toluene (60 mL) at 0 ꢀC. The reaction mixture was
stirred at 0 ꢀC for 30 min under air, and then aqueous saturated KF
(10 mL) was added. The resultant mixture was extracted with Et2O
(30 mL ꢃ2), and the combined organic layers were washed with
aqueous saturated KF (10 mL), H2O (10 mL) and brine (10 mL), dried
over Na2SO4, filtered, and concentrated. The residue was purified by
flash chromatography [a column consecutively packed withsilica gel
10 g and 10% (w/w) KF contained silica gel 5 g, pentane to pentane/
EtOAc 9/1] to afford tetraene 24aa (45.4 mg, 0.0596 mmol) in 48%
4.1.39. Tetraene 24bb. According to the synthetic procedure of
tetraene 24aa, 24bb (45.1 mg, 59.2 mmol) was synthesized from
23bb (118 mg, 0.113 mmol) in 52% yield by using n-Bu3SnH
(0.45 mL, 1.7 mmol) and N-methylmorpholine N-oxide (133 mg,
1.14 mmol) in toluene (55 mL). Purification was performed by flash
chromatography [a column consecutively packed with silica gel 8 g
and 10% (w/w) KF contained silica gel 2 g, pentane to pentane/
EtOAc 9/1]: colorless oil; [
a]
25ꢄ26 (c 0.83, CHCl3); HRMS (ESI) calcd
D
for C41H70O7SSi2Na 785.4273 [MþNa]þ, found 783.4259. The other
analytical data of 24bb were identical to those of 24aa.
yield: colorless oil; [
a]
D
24þ24 (c 1.3, CHCl3); IR (neat)
n
2952, 2928,
4.1.40. (12S,17R,18S)-1aa. TMSOTf (0.16 mL, 0.86 mmol) was added
to a solution of 24aa (42.9 mg, 56.3 mmol) and 2,6-lutidine (0.15 mL,
2956, 1462, 1366, 1254, 1189, 1177, 1073 cmꢄ1
;
1H NMR (500 MHz,
CDCl3)
d
0.00 (3H, s, CH3 of TBS), 0.03 (3H, s, CH3 of TBS), 0.04 (3H, s,
1.3 mmol) in CH2Cl2 (1.2 mL) at ꢄ15 ꢀC. The reaction mixture was
stirred at ꢄ15 ꢀC for 15 min, and then H2O (2.0 mL) and EtOAc
(2.0 mL) were successively added. The resultant solution was
warmed to room temperature and stirred for 30 min. After sepa-
ration, the organic layer was washed with aqueous 0.1 M HCl so-
lution (10 mL ꢃ2), aqueous saturated NaHCO3 solution (10 mL), H2O
(10 mL) and brine (10 mL), dried over Na2SO4, filtered, and con-
centrated to afford the crude aldehyde 25aa, which was used in the
next reaction without further purification.
CH3 of TBS), 0.05 (3H, s, CH3 of TBS), 0.74 (3H, t, J¼7.8 Hz, H20), 0.84
(9H, s, t-Bu of TBS), 0.90 (9H, s, t-Bu of TBS),1.45e1.56 (3H, m, H3 and
H19a), 1.63e1.71 (2H, m, H2), 1.77 (1H, m, H19b), 1.98e2.30 (6H, m,
H4, H13 and H16), 2.44 (3H, s, CH3 of Ts), 2.91 (2H, m, H7), 3.79 (1H,
ddd, J¼9.2, 4.1, 4.1 Hz, H17), 3.82e3.89 (2H, m, acetal), 3.91e3.99 (2H,
m, acetal), 4.18 (1H, dt, J¼6.4, 6.4 Hz, H12), 4.30 (1H, dt, J¼9.2, 4.1 Hz,
H18), 4.85 (1H, t, J¼4.6 Hz, H1), 5.30e5.51 (5H, m, H5, H6, H8, H14
and H15), 5.64 (1H, dd, J¼15.1, 6.4 Hz, H11), 5.97 (1H, dd, J¼11.0,
11.0 Hz, H9), 6.47 (1H, dd, J¼15.1, 11.0 Hz, H10), 7.33 (2H, d, J¼8.3 Hz,
aromatic), 7.79(2H, d, J¼8.3 Hz, aromatic).13C NMR (125MHz, CDCl3)
A solution of NaClO2 (80 wt %, 56.3 mg, 0.498 mmol) and
NaH2PO4∙2H2O (82.5 mg, 0.529 mmol) in H2O (0.6 mL) was added