Sodium hydride → ethyl[5,5-dimethyltetrahydro-1'H-spiro[1,3-dioxane-2,2'-pentalen]-5'(3'H)-ylidene]ethanoate

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Reaction Conditions

Reaction Steps

Sodium hydride (60% dispersion in mineral oil, 134 mg, 3.34 mmol) was suspended in THF (2 mL) and cooled to 0° C. Triethylphopsphonoacetate (0.55 g, 2.45 mmol) was added dropwise and the mixture was stirred at 0° C. for 30 min. The product of Step 1 (500 mg, 2.229 mmol) was added dropwise as a solution in THF (0.5 mL) and the reaction mixture was stirred 16 hrs while warming from 0° C. to room temperature. The mixture was partitioned between EtOAc and water, the organic layer dried over Na2SO4, concentrated under reduced pressure and the residue was purified by flash chromatography (7 to 60% EtOAc in hexanes) to give ethyl[5,5-dimethyltetrahydro-1′H-spiro[1,3-dioxane-2,2′-pentalen]-5′(3′H)-ylidene]ethanoate (460 mg, 1.563 mmol, 70.1% yield) as a colorless oil. MS ESI: [M+Na]+ m/z 295.7.

Provenance & Evidence