2,6-Lutidine → (3r,5r)-3-{[Tert-butyl(dimethyl)silyl]oxy}-5-{[tert-butyl(diphenyl)silyl]oxy}-4-methylenecyclohexanone

Participants

Reaction Conditions

Reaction Steps

The compound of Example 13D (8.5 g, 17 mmol) was dissolved in 50 mL of dichloromethane; 4.4 mL of 2,6-lutidine was added, and the resultant solution was cooled to 0° C. tert-Butyldimethylsilyl trifluoromethanesulfonate (5.9 mL) was added, and the mixture was stirred for 1 hour. The reaction was quenched by the addition of saturated aqueous NH4Cl, the solvents were removed in vacuo, and the residue was partitioned between ethyl acetate and water. The organic phase was washed with 1 N aqueous HCl, then brine, and dried over Na2SO4. The solvents were removed in vacuo; the residue was purified by chromatography on an Analogix IntelliFlash 280™, eluting with a gradient of 2% to 5% ethyl acetate in hexanes. The product (9.3 g) was dissolved in 75 mL of ethanol; pyridinium p-toluenesulfonate (390 mg) was added, and the mixture was stirred at ambient temperature for 1 hour. The solvents were removed in vacuo; the residue was purified by chromatography on an Analogix Intelliflash 280™, eluting with a gradient of 9% to 17% ethyl acetate in hexanes. A sample of this product (5.8 of 6.8 g) was dissolved in 30 mL of dichloromethane; 3.0g of NaHCO3 was added, and the mixture was cooled to 0° C. Dess-Martin reagent (5.9 g) was added, and stirring was continued for 2 hours. The solvents were removed in vacuo, and the residue was partitioned between ethyl acetate and water. The organic phase was washed with 1 N aqueous HCl, then brine, and dried over Na2SO4. The organic phase was passed through a plug of silica gel and concentrated in vacuo, giving the titled compound (5.5 g, 71%).

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