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Following a published procedure,24 a solution of 3 (3.65 g, 10.2 mmol) in dry toluene (52 mL) at −78° C. under argon was treated with DIBALH (12 mmol, 8.3 mL, 1.5 M solution in toluene), and the reaction was allowed to proceed for 1 h. Water (2.6 mL) was added, and the mixture was allowed to reach room temperature. Aqueous NaOH (2.6 mL, 4.0 M solution) was added, and stirring was continued for 15 min. Water (7.8 mL) was added and the suspension was stirred for a further 15 min. The sample was dried (Na2SO4), concentrated at reduced pressure, and chromatographed [silica, petroleum ether/diethyl ether (20:1)], affording a colorless liquid (2.70 g, 73%): IR (film, νmax cm−1) 2955, 2859, 1729, 1708, 1472; 1H NMR δ 0.01 (s, 12H), 0.87 (s, 18H), 1.64-1.74 (m, 2H), 1.85-1.96 (m, 2H), 2.50 (m, 1H), 3.57-3.68 (m, 4H), 9.65 (d, J=2.4 Hz, 1H); 13C NMR δ −5.27, 18.45, 26.09, 32.15, 46.40, 60.80, 204.74; EI-MS 171/172, 141, 97, 75, calcd 360.2516 (C18H40O3Si2); Anal. Calcd C, 59.94; H, 11.18. Found: C, 58.15; H, 11.16.

1. customat −78° C.
2. customto reach room temperature
3. waitwas continued for 15 min
4. stirringthe suspension was stirred for a further 15 min
5. dry with materialThe sample was dried (Na2SO4)
6. concentrationconcentrated at reduced pressure
7. customchromatographed [silica, petroleum ether/diethyl ether (20:1)]