Cyclopentanone → (2R,5S)-2-t-Butyl-5-(1-hydroxycyclopentyl)-5-phenyl-1,3-dioxolan-4-one

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Reaction Steps

Lithium hexamethyldisilazide (0.8 g, 4.7 mmol; 4.7 mL of 1.0 M in hexanes) was added to anhydrous THF (5.3 mL, 65 mmol) at −78° C. Intermediate (1a) (800 mg, 3.6 mmol) in 5.3 mL anhydrous THF was added to the solution dropwise over 15 minutes. After 30 minutes cyclopentanone (451 μL, 5.1 mmol) was added dropwise over less than 1 minute. After 2 hours, 0.8 mL of saturated aqueous Na2HPO4 was added, and the mixture stirred at room temperature for 5 minutes. The mixture was added to 8 mL saturated aqueous ammonium chloride. The aqueous layer was washed (2×80 mL EtOAc), and the organic layers were combined, dried over Na2SO4, filtered and concentrated. The crude product (780 mg) was purified by flash chromatography (5-15% EtOAc gradient over 30 minutes with hexanes) to yield intermediate (1b).

Provenance & Evidence