ACCEPTED MANUSCRIPT
saturated NaHCO3 (aq). The organic phase was washed with saturated brine, dried with
MgSO4, and concentrated in vacuo. Purification by silica gel column chromatography
(hexanes:ethyl acetate = 10:1) gave 28b (20 mg, 0.038 mmol, 63%) as a colorless oil. Rf =
20
0.3 (hexanes:ethyl acetate = 4:1); [α]D −3.2 (c 0.15, CHCl3); IR (neat) ν max 3439, 2928,
1
2856, 1725, 1506, 1462, 1379, 1252, 1214, 1074, 925, 837, 776, 697; H NMR (CDCl3, 300
MHz) δ 7.29‒7.43 (m, 5 H), 5.68‒6.02 (m, 2 H), 5.41 (d, J = 9.4 Hz, 1 H), 5.02‒5.32 (m, 6
H), 4.14‒4.26 (m, 2 H), 4.09 (t, J = 6.4 Hz, 1 H), 3.90 (dd, J = 7.7, 4.4 Hz, 1 H), 3.84 (dd, J =
9.4, 5.1 Hz, 1 H), 2.71‒2.81 (m, 1 H), 2.12‒2.37 (m, 2 H), 1.37‒1.44 (m, 6 H), 0.88‒0.93 (m,
13
9 H), 0.02‒0.09 (m, 6 H); C NMR (CDCl3, 75 MHz) δ 156.2, 137.2, 136.4, 134.1, 128.5,
128.2, 128.1, 118.2, 116.8, 109.5, 82.1, 78.7, 74.1, 69.0, 66.9, 54.6, 38.3, 26.9, 26.8, 25.9,
18.3, 17.5, −4.5, −4.8; HRMS (EI+) [(M+H)+] m/z calcd. for C27H44NO6Si 506.2932; found
506.2934.
4.8. Benzyl
(5R,6R,7R)-5-allyl-7-((4R,5S)-2,2-dimethyl-5-vinyl-1,3-dioxolan-4-yl)-
2,2,3,3,9,9,10,10-octamethyl-4,8-dioxa-3,9-disilaundecan-6-ylcarbamate (29)
To a solution of 28a (100 mg, 0.2 mmol) in DMF (2 mL) were added TBSCl (94 mg, 0.6
mmol) and imidazole (52 mg, 0.6 mmol) at 40 °C. After 12 h, the reaction mixture was
washed with H2O, dried with MgSO4, and concentrated in vacuo. Purification by silica gel
chromatography (hexanes:ethyl acetate = 30:1) gave 29 (110 mg, 0.18 mmol, 89% yield) as a
20
colorless oil. Rf = 0.4 (hexanes:ethyl acetate = 6:1); [α]D −1.4 (c 0.35, CHCl3); IR (neat) ν
max 3439, 2955, 2930, 2895, 2857, 1728, 1507, 1472, 1379, 1254, 1213, 1070, 926, 837, 776,
697; 1H NMR (CDCl3, 300 MHz) δ 7.30‒7.39 (m, 5 H), 5.77‒5.99 (m, 2 H), 5.03‒5.29 (m, 7
H), 4.23 (dd, J = 5.6, 3.8 Hz, 1 H), 4.17 (dd, J = 9.1, 6.1 Hz, 1 H), 4.00‒4.12 (m, 2 H), 3.91
(td, J = 8.9, 1.8 Hz, 1 H), 2.49 (dt, J = 14.0, 7.0 Hz, 1 H), 2.28 (dt, J = 14.0, 7.0 Hz, 1 H),
13
1.41 (s, 6 H), 0.81‒0.97 (m, 18 H), −0.01 to 0.16 (m, 12 H); C NMR (CDCl3, 75 MHz) δ
156.1, 137.3, 136.5, 135.2, 128.4, 128.4, 128.1, 117.4, 116.8, 109.7, 82.4, 74.6, 74.1, 72.6,
66.8, 57.5, 38.0, 27.2, 27.2, 26.1, 25.9, 18.4, 18.1, −4.4, −4.7; HRMS (EI+) [(M+H)+] m/z
calcd. for C33H58NO6Si2 620.3797; found 620.3792.
4.9. Benzyl (5R,6R,7R)-5-(2-hydroxyethyl)-7-((4R,5S)-5-(hydroxymethyl)-2,2-dimethyl-
1,3-dioxolan-4-yl)-2,2,3,3,9,9,10,10-octamethyl-4,8-dioxa-3,9-disilaundecan-6-
ylcarbamate (30)
Compound 29 (100 mg, 0.17 mmol) was dissolved in dry methanol (1.7 mL) and cooled to
−78 °C. Ozone was then passed through the solution until the reaction was complete. The
reaction mixture was quenched with NaBH4 (64 mg, 1.7 mmol) and allowed to warm to rt for
3 h. Distilled water was added to quench the reaction, the organic layer was separated, and
the aqueous layer was extracted with ethyl acetate. The combined organic layers were washed
with brine, dried with MgSO4, and filtered. The filtrate was concentrated in vacuo.
Purification by silica gel column chromatography (hexanes:ethyl acetate = 4:1) gave 30 (60
20
mg, 0.095 mmol, 56% yield) as a colorless oil. Rf = 0.3 (hexanes:ethyl acetate = 2:1); [α]D
−16.7 (c 0.1, CHCl3); IR (neat) ν max 3440, 2953, 2931, 2887, 2857, 1704, 1529, 1472, 1380,
1
1254, 1060, 837, 776, 697; H NMR (CDCl3, 300 MHz) δ 7.29‒7.39 (m, 5 H), 5.58 (d, J =
7.5 Hz, 1 H), 5.14 (d, J = 12.2 Hz, 1 H), 5.01 (d, J = 12.2 Hz, 1 H), 4.15‒4.32 (m, 2 H), 3.92‒
4.05 (m, 2 H), 3.85 (ddd, J = 10.7, 7.1, 4.5 Hz, 1 H), 3.71 (dt, J = 10.4, 5.3 Hz, 1 H), 3.53‒
3.64 (m, 3 H), 2.20‒2.50 (m, 2 H), 1.65‒1.94 (m, 2 H), 1.34‒1.45 (m, 6 H), 0.82‒0.95 (m, 18
13
H), 0.02‒0.15 (m, 12 H); C NMR (CDCl3, 75 MHz) δ 156.8, 136.6, 128.5, 128.4, 128.2,
10