B. Jin et al. / Tetrahedron 61 (2005) 401–408
407
gave 196 as a colorless crude oil, which was used in the next
step without further purification. To a solution of the above-
generated alcohol 24 in CH2Cl2 (5 mL) at 0 8C was added a
solution of I2 (1.4 g, 5.4 mmol) in CH2Cl2 (45 mL) until
brown color persisted. Imidazole (1 g, 14.8 mmol) was then
added followed by TBSCl (2.23 g, 14.8 mmol). The
resulting slurry was stirred at 0 8C for 20 min and quenched
with Na2S2O3 (25 mL) and stirred for 5 min. The aqueous
layer was separated and extracted with ether (3!100 mL).
The combined organic layers were dried briefly over
Na2SO4 and concentrated in vacuo. Flash chromatography
of the residue (petroleum ether–ether: 100:0/20:1) gave
1.35 g (83%, 3 steps) of 25 as a colorless oil. Observed
physical properties were identical with those previously
reported.23 1H NMR (500 MHz, CDCl3) d 6.14 (tq, JZ8.0,
1.0 Hz, 1H), 3.59 (t, JZ6.5 Hz, 2H), 2.35 (s, 3H), 2.22 (q,
JZ6.5 Hz, 2H), 0.87 (s, 9H), 0.03 (s, 6H); 13C NMR
(125 MHz, CDCl3) d 137.7, 95.3, 61.8, 34.2, 27.7, 25.9,
18.3, K5.3; HRMS (ESI) m/z 333.0731 [(MCLi)C, calcd
for C11H23IOSi 333.0723].
18.2, 13.6, 12.7, K4.2, K4.9, K5.2, K5.3; HRMS (ESI)
m/z 587.1530 [(MCLi)C, calcd for C24H46Br2O2Si2
587.1563].
5.1.17. 6-Bromo-9,15-bis-(tert-butyl-dimethyl-silanyl-
oxy)-2,4,8,12-tetramethyl-pentadeca-2,4,6,10,12-penta-
enoic acid 2-trimethylsilanyl-ethyl ester 28. To a solution
of 27 (38 mg, 0.0656 mmol) and 7 (115 mg, 0.32 mmol) in
THF–H2O (3–1 mL, degassed) was added Pd(PPh3)4
(7.6 mg, 0.00656 mmol). After 5 min, TlOEt (8 mL,
0.118 mmol) was introduced and the mixture was stirred
in the dark for 30 min. The resulting yellow slurry was
filtered through a bed of Celite and rinsed with ether
(100 mL). Solvent was removed in vacuo. Flash chroma-
tography of the residue (petroleum ether–ether: 50:1) gave
1
8.4 mg (36%) of 28 as a colorless oil. H NMR (500 MHz,
CDCl3) d 7.08 (s, 1H), 6.13 (d, JZ15.5 Hz, 1H), 6.04 (d,
JZ1.0 Hz, 1H), 5.65 (dd, JZ9.0, 1.0 Hz, 1H), 5.53 (dd, JZ
15.5, 7.0 Hz, 1H), 5.42 (t, JZ7.5 Hz, 1H), 4.23 (m, 2H),
4.10 (t, JZ6.0 Hz, 1H), 3.62 (t, JZ7.0 Hz, 2H), 2.78 (m,
1H), 2.34 (q, JZ7.0 Hz, 2H), 2.00 (d, JZ1.5 Hz, 3H), 1.92
(d, JZ1.5 Hz, 3H), 1.72 (s, 3H), 1.02 (d, JZ6.5 Hz, 3H),
1.01 (m, 2H), 0.87 (s, 9H), 0.86 (s, 9H), 0.04 (s, 9H), 0.02 (s,
6H), 0.01 (s, 3H), K0.02 (s, 3H); 13C NMR (125 MHz,
CDCl3) d 168.8, 141.1, 136.4, 135.5, 135.4, 134.6, 133.8,
128.5, 128.3, 128.1, 119.7, 76.6, 63.0, 62.7, 44.3, 32.0, 25.9,
25.8, 18.4, 18.2, 18.1, 17.3, 14.8, 14.2, 12.6, K1.5, K4.1,
K4.9, K5.3, K5.3; HRMS (ESI) m/z 733.3690 [(MCLi)C,
calcd for C36H67BrO4Si3Li 733.3691].
5.1.15. 3,9-Bis-(tert-butyl-dimethyl-silanyloxy)-2,6-
dimethyl-nona-4,6-dienal 26. To a solution of 25 (87 mg,
0.246 mmol) and 7 (53 mg, 0.164 mmol) in THF–H2O
(3–1 mL, degassed) was added Pd(PPh3)4 (19 mg,
0.0164 mmol). After 5 min, TlOEt (17 mL, 0.246 mmol)
was introduced and the mixture was stirred in the dark for
35 min. The resulting reddish-brown slurry was filtered
through a bed of Celite and rinsed with ether (200 mL).
Solvent was removed in vacuo. Flash chromatography of
the residue (petroleum ether–ether: 20:1) gave 56.3 mg
(80%) of 26 as a colorless oil. 1H NMR (500 MHz,
CDCl3) d 9.74 (d, JZ1.5 Hz, 1H), 6.18 (d, JZ15.5 Hz,
1H), 5.48 (dd, JZ15.5, 7.0 Hz, 1H), 5.45 (t, JZ7.7 Hz,
1H), 4.54 (dd, JZ6.5, 5.0 Hz, 1H), 3.62 (t, JZ7.0 Hz,
2H), 2.46 (m, 1H), 2.34 (q, JZ6.5 Hz, 2H), 1.71 (s, 3H),
1.04 (d, JZ7.0 Hz, 3H), 0.86 (s, 9H), 0.85 (s, 9H), 0.02
(s, 6H), 0.01 (s, 6H); 13C NMR (125 MHz, CDCl3) d
204.8, 136.1, 134.3, 129.5, 126.6, 73.8, 62.6, 53.2, 32.1,
25.9, 25.8, 18.3, 18.1, 12.6, 8.5, K4.1, K5.0, K5.3, K5.3;
HRMS (ESI) m/z 433.3149 [(MCLi)C, calcd for
C23H46O3Si2 433.3146].
5.1.18. 9,15-Bis-(tert-butyl-dimethyl-silanyloxy)-2,4,6,
8,12-pentamethyl-pentadeca-2,4,6,10,12-pentaenoic acid
2-trimethylsilanyl-ethyl ester 29. To a solution of 28
(50 mg, 0.068 mmol) in THF (3 mL, degassed) was
sequentially added Pd(PPh3)4 (8 mg, 0.0068 mmol), Me-9-
B-BBN 189 (378 mL, 0.68 mmol, 1.8 M in THF), TlOEt
(9 mL, 0.12 mmol), and H2O (0.6 mL, degassed). The
yellow slurry was stirred in the dark for 23 h. HPLC
analysis of the reaction mixture showed complete consump-
tion of starting material 200. The resulting dark slurry was
filtered through a bed of Celite and rinsed with ether
(100 mL). Solvent was removed in vacuo. Flash chroma-
tography of the residue (petroleum ether–ether: 20:1) gave
36.6 mg (81%) of 201 as a colorless oil. Further purification
by HPLC (silica gel, 4 mL/min, 269 nm detection, 0/3%
gradient EtOAc/hexanes) gave 29 mg (64%) of analytically
5.1.16. 1,1-Dibromo-4,10-bis-(tert-butyl-dimethyl-silanyl-
oxy)-3,7-dimethyl-deca-1,5,7-triene 27. To a slurry of
Ph3P–CHBr3 (579 g, 1.12 mmol) in THF (2 mL) at 0 8C was
added t-BuOK (67 mg, 0.6 mmol). The bright yellow slurry
was stirred at ambient temperature for 20 min and cooled to
0 8C. A solution of 26 (32 mg, 0.075 mmol) in THF (4 mL)
was then introduced via cannula. The reaction mixture was
stirred at 0 8C for 1 h and quenched with brine (10 mL). The
aqueous layer was separated and extracted with ether (3!
50 mL). The combined organic layers were dried over
Na2SO4 and concentrated in vacuo. Flash chromatography
of the residue (petroleum ether–ether: 30:1) gave 38.2 mg
(88%) of 27as a colorless oil. 1H NMR (500 MHz, CDCl3) d
6.27 (d, JZ9.5 Hz, 1H), 6.13 (d, JZ15.5 Hz, 1H), 5.46 (dd,
JZ15.5, 7.0 Hz, 1H), 5.44 (t, JZ7.0 Hz, 1H), 4.11 (t, JZ
5.5 Hz, 1H), 3.63 (t, JZ6.5 Hz, 2H), 2.53 (m, 1H), 2.35
(q, JZ7.0 Hz, 2H), 1.72 (s, 3H), 0.96 (d, JZ6.5 Hz, 3H),
0.88 (s, 9H), 0.87 (s, 9H), 0.03 (s, 6H), 0.02 (s, 3H), K0.03
(s, 3H); 13C NMR (125 MHz, CDCl3) d 141.7, 135.5, 134.5,
128.8, 127.5, 87.8, 75.6, 62.7, 45.3, 32.1, 25.9, 25.8, 18.4,
1
pure 29 as a colorless oil. H NMR (500 MHz, CDCl3) d
7.13 (s, 1H), 6.05 (d, JZ16.0 Hz, 1H), 6.04 (s, 1H), 5.43
(dd, JZ16.0, 7.0 Hz, 1H), 5.38 (t, JZ7.0 Hz, 1H), 5.20 (dt,
JZ10.0, 1.5 Hz, 1H), 4.23 (m, 2H), 3.91 (t, JZ6.0 Hz, 1H),
3.61 (t, JZ7.0 Hz, 2H), 2.33 (q, JZ7.0 Hz, 2H), 2.29 (m,
1H), 2.01 (d, JZ1.5 Hz, 3H), 1.82 (d, JZ1.0 Hz, 3H), 1.76
(s, 3H), 1.68 (s, 3H), 1.03 (m, 2H), 0.89 (d, JZ7.0 Hz, 3H),
0.87 (s, 9H), 0.86 (s, 9H), 0.04 (s, 9H), 0.02 (s, 6H), 0.00
(s, 3H), K0.05 (s, 3H); 13C NMR (125 MHz, CDCl3) d
169.2, 142.8, 134.9, 134.7, 134.6, 133.2, 133.1, 131.5,
129.2, 127.9, 126.2, 77.5, 62.8, 62.7, 40.8, 32.1, 25.9, 23.6,
18.3, 18.2, 18.0, 17.4, 15.4, 14.1, 12.6, K1.4, K4.1, K4.8,
K5.2, K5.3; HRMS (ESI) m/z 685.4479 [(MCNa)C, calcd
for C37H70O4Si3Na 685.4480].