J. C. Anderson et al. / Tetrahedron 56 (2000) 8747±8767
8761
J6.7 Hz, CHMe), 1.26 (3H, s, CMe), 1.27 (3H, s, CMe),
1.56±1.72 (1H, m, CHMe), 2.45 (,1H, bs, OH), 2.78 (1H,
dd, J9.5, 4.0 Hz, C39±H), 2.94 (1H, ddd, J6.7, 5.5,
4.0 Hz, C38±H), 3.50 (1H, dd, J12.4, 6.8 Hz, HCHOH),
3.70 (1H, dd, J12.4, 5.1 Hz, HCHOH), 3.80 (1H, dd,
J8.5, 6.4 Hz, HC44H), 3.93 (1H, dd, J8.5, 6.1 Hz,
HC44H), 3.98 (1H, dd, J3.8, 2.9 Hz, CHOTBS), 4.13±
4.24 (1H, m, C43±H), 5.16 (1H, dd, J7.6, 3.7 Hz,
CHOBz), 7.30±7.60 (5H, m, ArH); m/z (CI1) 498 (47%,
MNH14 ), 481.2621 (86% MH1, C25H41O7Si requires
481.2622), 365 (43%), 265 (77%), 300 (55%), 105 (100%,
Bz1); X-ray crystal structure data con®rmed the stereo-
chemistry of the major epoxide as that drawn.
organic layers were dried (MgSO4) and concentrated in
vacuo. Puri®cation by ¯ash column chromatography (96:4
pet. ether/EtOAc) gave bis-TES protected alkene 30c
(1.28 g, 99%) as a colourless oil [a]D142.1 (c 1.9,
CH2Cl2); IR (solution in CH2Cl2) nmax/cm21 1728 (CvO),
1603 (Ar), 1586 (Ar); dH (250 MHz, CDCl3) 20.16 (3H, s,
SiMe), 20.02 (3H, s, SiMe), 20.00 (6H, s, 2£SiMe), 0.40±
0.63 (12H, m, 6£SiCH2Me), 0.75 (9H, s, SitBu), 0.80±0.94
(18H, m, 6£SiCH2Me), 0.84 (9H, s, SitBu), 1.04 (3H, d,
J6.7 Hz, CHMe), 2.54±2.70 (1H, m, CHMe), 3.55 (1H,
dd, J10.4, 6.7 Hz, HCHOTES), 3.71 (1H, dd, J10.4,
4.9 Hz, HCHOTES), 3.90 (1H, dd, J7.0, 3.7 Hz,
CHOTBS), 3.91±3.98 (1H, m, CHOTES), 4.09 (1H, dd,
J13.1, 3.4 Hz, HCHOTBS), 4.24 (1H, dd, J13.1,
5.8 Hz, HCHOTBS), 5.19 (1H, dd, J7.0, 4.1 Hz,
CHOBz), 7.31±7.48 (2H, m, CHvCH), 7.32±7.53 (3H,
m, 3£ArH), 7.92±8.00 (2H, m, 2£ArH); dC (62.9 MHz,
CDCl3) 4.2, 5.1, 6.4, 6.8, 6.9, 15.3, 18.3, 25.9, 26.0, 35.5,
59.6, 64.4, 73.5, 73.6, 128.2, 129.0, 129.8, 131.0, 132.6,
134.1, 165.9; m/z (CI1) 784 (6% MNH14 ), 767.4925 (11%
MH1, C40H79O6Si4 requires 767.4954), 567 (85%), 381
(100%); (Found C, 62.48; H, 10.43. C40H78O6Si4 requires
C, 62.61; H, 10.24).
1H NMR data for minor epoxide isomer dH (250 MHz,
CDCl3) 20.06 (3H, s, SiMe), 0.00 (3H, s, SiMe), 0.77
(9H, s, SitBu), 0.91 (3H, d, J7.0 Hz, CHMe), 1.20 (3H,
s, CMe), 1.23 (3H, s, CMe), 1.38±1.55 (.1H, m, CHMe),
2.86 (1H, dd, J9.6, 4.4 Hz, C39±H), 3.08 (1H, dt, J6.4,
4.3 Hz, C38±H), 3.55 (1H, dd, J12.2, 6.4 Hz, HCHOH),
3.75 (1H, dd, J12.2, 3.7 Hz, HCHOH), 3.77±3.97 (2H, m,
C44±H2), 4.02 (1H, dd, J5.2, 3.4 Hz, CHOTBS), 4.16 (1H,
q, J6.5 Hz, C43±H), 5.28 (1H, t, J5.8 Hz, CHOBz),
7.30±7.60 (5H, m, ArH).
(2Z,4R,5R,6R,7R)-6-Benzoyloxy-4-methyl-1,5-di-(tert-
butyldimethylsiloxy)-7,8-di-(triphenylsilyloxy)oct-2-ene
(30d). To a solution of diol 28 (50 mg, 0.093 mmol) in N,N-
dimethylformamide (1.5 mL) was added imidazole (45 mg,
0.743 mmol) followed by triphenylsilyl chloride (110 mg,
0.372 mmol). After 18 h water (5 mL) was added and the
mixture was extracted with Et2O (3£5 mL). The combined
organic layers were dried (MgSO4) and concentrated in
vacuo. The crude mixture was then ®ltered through a short
plug of silica (95:5 pet. ether/EtOAc) to give crude bis-TPS
alkene 30d (91 mg, 96%) as a colourless viscous oil which
was contaminated with TPSOH. Alkene 30d was then used
without further puri®cation due to instability [a]D134.5
(c 2.9, CH2Cl2); IR (solution in CH2Cl2) nmax/cm21 3070±
2856 (C±H), 1727 (CvO), 1602 (Ar), 1590 (Ar); dH
(250 MHz, CDCl3) 0.18 (3H, s, SiMe), 0.02 (3H, s,
SiMe), 0.00 (3H, s, SiMe), 0.01 (3H, s, SiMe), 0.69±0.85
(3H, m, CHMe), 0.80 (9H, s, SitBu), 0.90 (9H, s, SitBu),
2.46±2.62 (1H, m, CHMe), 3.86 (1H, dd, J13.3, 3.7 Hz,
HCHOTBS), 3.97±4.20 (4H, m, HCHOTBS, CH2OTPS,
CHOTBS), 4.33±4.43 (1H, m, CHOTPS), 5.30±5.55 (2H,
m, CHvCH), 5.51 (1H, dd, J7.3, 3.1 Hz, CHOBz), 7.10±
8.01 (.20H, m, ArH); dC (62.9 MHz, CDCl3) 14.9, 18.1,
25.9, 35.5, 59.5, 64.7, 73.5, 74.1, 76.8, 127.8 (two over-
lapping), 128.1, 129.0, 129.9, 130.0 (two overlapping),
130.8, 132.5, 133.3, 133.7, 134.0, 135.2, 135.5, 135.6,
165.6; m/z (FAB1) 1055.4992 (17% MH1, C64H79O6Si4
requires 1055.4954), 855 (100%), 998 {18% (M2tBu)1},
{18% (M2Ph)1}, 923 {37% (M2TBSO)H1}; (Found C,
72.76; H, 7.36. C64H78O6Si4 requires C, 72.82; H, 7.45).
(2Z,4R,5R,6R,7R)-6-Benzoyloxy-4-methyl-1,5-di-(tert-
butyldimethylsiloxy)-7,8-di-(trimethylsilyloxy)oct-2-ene
(30b). To a solution of diol 28 (109 mg, 0.20 mmol) in N,N-
dimethylformamide (2 mL) was added triethylamine
(0.22 mL, 1.62 mmol) followed by trimethylsilyl chloride
(0.10 mL, 0.81 mmol) resulting in a cloudy white mixture.
After 5 min, water (5 mL) was added and the mixture was
extracted with Et2O (3£7 mL). The combined organic layers
were dried (MgSO4) and concentrated in vacuo. The crude
mixture was then ®ltered through a short plug of silica (9:1
pet. ether/EtOAc) to give bis-TMS protected alkene 30b
(135 mg, 99%) as a light yellow oil [a]D137.5 (c 2.4,
CH2Cl2); IR (solution in CH2Cl2) nmax/cm21 1727 (CvO),
1604 (Ar), 1586 (Ar); dH (250 MHz, CDCl3) 20.20 (3H, s,
SiMe), 20.08 (3H, s, SiMe), 20.07 (6H, s, 2£SiMe), 20.05
(9H, s SiMe3), 0.00 (9H, s, SiMe3), 0.69 (9H, s, SitBu), 0.76
(9H, s, SitBu), 0.92 (3H, d, J6.7 Hz, CHMe), 2.47±2.63
(1H, m, CHMe), 3.42 (1H, dd, J10.4, 7.3 Hz,
HCHOTMS), 3.55 (1H, dd, J10.5, 4.1 Hz, HCHOTMS),
3.76 (1H, dd, J6.1, 4.0 Hz, CHOTBS), 3.85 (1H, dt,
J7.0, 4.6 Hz, CHOTMS), 4.03 (1H, dd, J13.1, 4.4 Hz,
HCHOTBS), 4.14 (1H, dd, J13.1, 6.0 Hz, HCHOTBS),
5.07 (1H, dd, J6.1, 4.9 Hz, CHOBz), 5.21±5.41 (2H, m,
CHvCH), 7.26±7.35 (2H, m, 2£ArH), 7.42 (1H, tt, J6.1,
1.8 Hz, ArH), 7.86±7.93 (2H, m, 2£ArH); dC (62.9 MHz,
CDCl3) 20.61, 0.63 15.4, 16.4, 18.3, 26.0 (two over-
lapping), 35.5, 59.7, 63.8, 73.3, 74.0, 128.2, 129.1, 129.8,
130.0, 130.9, 132.7, 134.1, 165.8; m/z (CI1) 700 (100%
MNH14 ), 683.4017 (45% MH1, C34H67O6Si4 requires
683.4015), 105 (40% Bz1).
(2R,3S,4R,5R,6R,7R)-6-Benzoyloxy-4-methyl-1,5-di-(tert-
butyldimethylsiloxy)-7,8-di-(trimethylsilyloxy)octa-2,3-
oxirane (31b-syn). To a solution of alkene 30b (95 mg,
0.06 mmol) in CH2Cl2 (1 mL) at 2208C was added
DMDO25 (0.08 M in acetone; 2.6 mL, 0.21 mmol). After
18 h at this temperature the solution was warmed to room
temperature and then the volatile material was removed in
vacuo to give a mixture of two epoxide diastereoisomers in
(2Z,4R,5R,6R,7R)-6-Benzoyloxy-4-methyl-1,5-di-(tert-
butyldimethylsiloxy)-7,8-di-(triethylsilyloxy)oct-2-ene
(30c). To a solution of diol 28 (910 mg, 1.69 mmol) in N,N-
dimethylformamide (10 mL) was added imidazole (611 mg,
10.15 mmol) followed by triethylsilyl chloride (0.852 mL,
5.07 mmol). After 18 h water (30 mL) was added and the
mixture was extracted with Et2O (3£30mL). The combined