J. Cossy et al. / Tetrahedron 58 (2002) 5909±5922
5915
(CDCl3, 300 MHz) d 7.72±7.66 (m, 4H), 7.50±7.35 (m, 6H),
5.96 (ddd, J16.9, 10.7 and 8.5 Hz, 1H), 5.13±5.03 (m, 2H),
3.75 (dd, J10.3 and 4.4 Hz, 1H), 3.69 (dd, J10.3 and
7.4 Hz, 1H), 3.54 (bs, 1H), 3.45 (bdd, J7.9 and 3.1 Hz,
1H), 2.39 (m, 1H), 1.85 (m, 1H), 1.12 (d, J7.0 Hz, 3H),
1.06 (s, 9H), 0.82 (d, J7.0 Hz, 3H).
(14), 105 (14); HRMS (CI1, NH3) calcd for C25H36O3NSi
(M1NH41): 426.2464, found 426.2447.
1.1.6. (5S, 6S)-6-{(1S)-2-[(tert-Butyldiphenylsilyl)oxy]-1-
methylethyl}-5-methyltetrahydro-2H-pyran-2-one (1)-8.
Amixture of lactone ( 1)-7 (164 mg, 0.40 mmol, 1 equiv.)
and Pd(OH)2 (40 mg) in EtOAc (1.5 mL) was stirred
overnight under a hydrogen atmosphere at rt. The reaction
mixture was ®ltered through Celite (rinsing with EtOAc) and
the solvent evaporated in vacuo. The residue was puri®ed by
¯ash chromatography (hexanes/EtOAc: 100/0 to 70/30) to
provide (1)-8 (151 mg, 0.37 mmol, 92% yield). Rf: 0.22
1.1.4. (1S, 2S)-1-{(1S)-2-[(tert-Butyldiphenylsilyl)oxy]-1-
methylethyl}-2-methylbut-3-enyl prop-2-enoate (1)-6.
To a stirred solution of (1)-5 (0.150 g, 0.39 mmol,
1 equiv.) in dry CH2Cl2 (1 mL), a catalytic amount of
DMAP (,15 mg) was added at rt. The reaction mixture
was cooled to 2788C. HuÈnig's base (0.21 mL, 1.21 mmol,
3.1 equiv.) was added dropwise, immediatly followed by
acryloyl chloride (0.04 mL, 0.49 mmol, 1.25 equiv.). After
2 h of stirring at 2788C, the reaction mixture was diluted
with CH2Cl2 (5 mL), quenched with brine (1 mL) and
warmed rapidly to rt. The aqueous layer was extracted
with CH2Cl2 (3£10 mL). The organic layer was dried over
MgSO4, ®ltered and concentrated in vacuo. Flash chroma-
tography (hexanes/Et2O: 100/0 to 90/10) provided (1)-6
(0.136 g, 0.31 mmol, 80% yield). Rf: 0.52 (hexanes/Et2O:
20
(hexanes/EtOAc: 70/30); [a]D 131.0 (c 1.0, CHCl3); IR
(neat) 1740 cm21; 1H NMR (CDCl3, 300 MHz) d 7.71±7.64
(m, 4H), 7.45±7.36 (m, 6H), 4.30 (dd, J10.3 and 1.5 Hz,
1H), 3.81 (dd, apparent t, J9.9 Hz, 1H), 3.59 (dd, J9.9
and 5.9 Hz, 1H), 2.61 (ddd, J17.7, 7.0 and 4.0 Hz, 1H),
2.45 (ddd, J17.7, 10.2 and 7.1 Hz, 1H), 2.07±1.77 (m, 3H),
1.56 (m, 1H), 1.07 (s, 9H), 0.98 (d, J6.3 Hz, 3H), 0.83
(d, J7.0 Hz, 3H); 13C NMR (CDCl3, 75 MHz) d 171.8
(s), 135.4 (4d), 133.6 (2s), 129.5 (2d), 127.5 (4d), 84.0 (d),
65.2 (t), 37.1 (d), 29.5 (t), 29.4 (d), 27.9 (t), 26.8 (3q), 19.1
(q), 17.1 (q), 8.8 (q); EI MS m/z (relative intensity) 365 (1),
353 (M2t-Bu, 21), 323 (78), 275 (89), 253 (9), 199 (100),
183 (18), 181 (15), 139 (13), 135 (10); HRMS (CI1, CH4)
calcd for C25H35O3Si (M1H1): 411.2355, found 411.2353.
20
95/5); [a]D 118.0 (c 1.0, CHCl3); IR (neat) 1730
1
cm21; H NMR (CDCl3, 300 MHz) d: 7.75±7.67 (m, 4H),
7.50±7.37 (m, 6H), 6.42 (dd, J17.3 and 1.8 Hz, 1H), 6.14
(dd, J17.3 and 10.3 Hz, 1H), 5.83 (dd, J10.3 and 1.8 Hz,
1H), 5.77 (ddd, J17.3, 10.3 and 8.8 Hz, 1H), 5.17 (dd,
apparent t, J5.9 Hz, 1H), 5.03±4.89 (m, 2H), 3.61 (dd,
J10.1 and 6.1 Hz, 1H), 3.53 (dd, J10.1 and 6.1 Hz,
1H), 2.48 (m, 1H), 2.04 (m, 1H), 1.12 (s, 9H), 1.02 (d, J
7.0 Hz, 3H), 0.99 (d, J7.0 Hz, 3H); 13C NMR (CDCl3,
75 MHz) d 165.7 (s), 139.8 (d), 135.5 (4d), 133.6 (2s),
130.1 (t), 129.5 (2d), 128.5 (d), 127.5 (4d), 115.2 (t), 76.9
(d), 65.6 (t), 40.4 (d), 37.2 (d), 26.8 (3q), 19.2 (s), 17.3 (q),
11.8 (q); EI MS m/z (relative intensity) 379 (M2t-Bu, 1),
269 (3), 253 (100), 239 (6), 223 (6), 199 (36), 193 (31), 183
(15), 135 (9), 109 (42).
1.1.7. (3R, 5S, 6S)-6-{(1S)-2-[(tert-Butyldiphenylsilyl)-
oxy]-1-methylethyl}-3,5-dimethyl-tetrahydro-2H-pyran-
2-one (9) and (3S, 5S, 6S)-6-{(1S)-2-[(tert-butyldiphenyl-
silyl)oxy]-1-methylethyl}-3,5-dimethyltetrahydro-2H-
pyran-2-one (10). Asolution of LDAwas generated at 0 8C
by dropwise addition of n-BuLi (0.09 mL, 2.5 M solution in
hexanes, 0.23 mmol, 1.0 equiv.) to a solution of diisopropyl-
amine (0.03 mL, 0.23 mmol, 1.0 equiv.) in THF (1.1 mL). A
solution of lactone (1)-8 (0.092 g, 0.23 mmol, 1 equiv.) in
THF (1.1 mL) was then added via cannula at 2788C. After
2 h of stirring at 2788C, the solution of enolate was added
dropwise via cannula to a precooled (2788C) solution of
methyl iodide (0.14 mL, 2.23 mmol, 10 equiv.) and HMPA
(0.12 mL, 0.67 mmol, 3 equiv.) in THF (1 mL). After
20 min at 2788C, the reaction mixture was diluted with
Et2O (7 mL) and quenched by addition of aqueous 2%
HCl solution (2 mL). The cooling bath was removed. The
aqueous layer was extracted with EtOAc (3£15 mL), dried
over MgSO4, ®ltered and evaporated. Puri®cation by TLC
(hexanes/EtOAc: 9/1) afforded a 1:1 mixture of the two
epimers 9 and 10 (0.068 g, 0.16 mmol, 70% yield). Rf:
0.50 (9) and 0.56 (10) (hexanes/Et2O: 80/20); IR (neat)
1.1.5. (5S, 6S)-6-{(1S)-2-[(tert-Butyldiphenylsilyl)oxy]-1-
methylethyl}-5-methyl-5,6-dihydro
2H-pyran-2-one
(1)-7. To a stirred solution of diene (1)-6 (0.460 g,
1.06 mmol, 1 equiv.) in dry CH2Cl2 (104 mL) was added
Ti(OiPr)4 (0.09 mL, 0.32 mmol, 0.3 equiv.). The reaction
mixture was re¯uxed 1 h before the addition in three
portions of Grubbs' catalyst I (3£29 mg, 0.16 mmol,
0.15 equiv.) in CH2Cl2 (3£1 mL) over 1 h. The reaction
mixture was re¯uxed overnight, cooled to rt, ®ltered over
a pad of silica gel (rinsing with EtOAc) and concentrated in
vacuo. Flash chromatography on silica gel (hexanes/EtOAc:
90/10 to 70/30) afforded (1)-7 (0.417 g, 1.02 mmol, 96%
1
(9110) 1730 cm21; H NMR (CDCl3, 300 MHz) (9110)
20
yield). Rf: 0.22 (hexanes/EtOAc: 80/20); [a]D 124 (c 1.0,
d 7.71±7.63 (m, 4H, 9 and 10), 7.47±7.36 (m, 6H, 9 and
10), 4.30 (dd, J10.5 and 1.3 Hz, 1H, 9), 4.27 (dd, J10.5
and 1.5 Hz, 1H, 10), 3.81 (dd, J9.9 and 8.8 Hz, 1H, 9 or
10), 3.78 (apparent t, J9.9 Hz, 1H, 9 or 10), 3.61 (dd,
J9.9 and 5.5 Hz, 1H, 9 or 10), 3.57 (dd, J9.9 and
5.9 Hz, 1H, 9 or 10), 2.53 (m, 1H, 9 and 10), 2.05±1.85
(m, 2H, 9 and 10), 1.73 (m, 1H, 9 and 10), 1.69 (m, 1H,
10), 1.35 (m, 1H, 9), 1.30 (d, J7.0 Hz, 3H, 9), 1.21 (d, J
7.0 Hz, 3H, 10), 1.07 (s, 9H, 9 and 10), 0.98 (d, J6.6 Hz,
3H, 10), 0.96 (d, J6.2 Hz, 3H, 9), 0.84 (d, J7.0 Hz, 3H,
10), 0.81 (d, J7.3 Hz, 3H, 9); 13C NMR (CDCl3, 75 MHz)
(9110) d 176.4, 174.4 (s), 135.4, 135.4 (d), 133.7±133.5
(s), 129.6, 129.5, 127.6, 127.5 (d), 85.3, 81.2 (d), 65.3 (t),
CHCl3); IR (neat) 1730, 1590 cm21 1H NMR (CDCl3,
;
300 MHz) d 7.64±7.48 (m, 4H), 7.37±7.20 (m, 6H), 6.58
(dd, J9.7 and 2.0 Hz, 1H), 5.87 (dd, J9.7 and 2.5 Hz,
1H), 4.33 (dd, J11.0 and 2.2 Hz, 1H), 3.73 (dd, J10.0
and 8.4 Hz, 1H), 3.51 (dd, J10.0 and 5.7 Hz, 1H), 2.55 (m,
1H), 1.91 (m, 1H), 1.01 (d, J7.2 Hz, 3H), 0.97 (s, 9H),
0.80 (d, J7.0 Hz, 3H); 13C NMR (CDCl3, 75 MHz) d
164.8 (s), 152.6 (d), 135.9 (4d), 134.0 (2s), 130.1 (2d),
128.1 (4d), 120.6 (d), 82.8 (d), 63.4 (t), 37.3 (d), 30.6 (d),
27.3 (3q), 19.7 (s), 16.5 (q) 10.3 (q); EI MS m/z (relative
intensity) 376 (3), 374 (3), 363 (1), 351 (M2t-Bu, 80), 321
(64), 269 (17), 239 (20), 199 (100), 191 (30), 183 (50), 135