Pyridine → 2,2,7,7-Tetramethyl-3,6-dioxa-2,7-disilaoctane

Participants

Reaction Steps

In a manner similar to that described in Tsunoda T., et al., Tet. Lett., 1980, 21(14), 1357-1358, Hwa et al., J. Org. Chem., 1987, 52(2), 188-191. A solution of 3β-acetoxy-17β-t-butyldimethylsilyloxy-androst-5-en-7-one (40.000 g, 86.821 mmol) from Example 16B or otherwise obtained and 1,2-bis(trimethylsiloxy)ethane (23.00 mL, 93.81 mmole) in CH2Cl2 (300 mL) is prepared at −78° C. Trimethylsilyl trifluoromethanesulfonate (0.20 mL, 1.035 mmol) is added under an inert atmosphere, the reaction is stirred for three hours, pyridine (2.00 mL, 24.73 mmol) is added and the stirred mixture is allowed to warm to room temperature. The organic solution is poured into saturated aqueous NaHCO3 (300 mL) and the resultant biphasic solution is extracted with EtOAc (3×300 mL). The combined organic extracts are washed with brine (200 mL), dried over MgSO4, filtered and evaporated to dryness. The residue is purified by flash chromatography (1:4 EtOAc/hexane) to give 7,7-ethylenedioxy-17β-t-butyldimethylsilylyoxy-androst-5-en-3-ol 3-acetate.

Provenance & Evidence