1,4-Dioxaspiro[4.5]decan-8-one → 8-Methylidene-1,4-dioxaspiro[4.5]decane

Participants

Reaction Conditions

Reaction Steps

To a solution of methyl triphenylphosphonium bromide (13.7 g, 38 mmol) in 1,4-dioxane (60 mL) was added potassium tert-butoxide (4.3 g, 38 mmol). The resulting yellow mixture was cooled to 0° C. in an ice-water bath and 1,4-dioxaspiro[4.5]decan-8-one (5 g, 32 mmol) was added slowly over 15 min as a solution in 1,4-dioxane (15 mL) via dropping funnel. The reaction was let stir and warm to rt over 1 h. The resulting brown-yellow reaction mixture was partitioned between methyl tert-butyl ether and saturated aqueous NH4Cl solution. The aqueous phase was extracted with methyl tert-butyl ether. The combined organic phases were washed with a saturated aqueous NaCl solution, dried over MgSO4, filtered and concentrated by rotary evaporation in vacuo to ˜20 mL. The resultant beige suspension was diluted with heptane and filtered. The filtrated was concentrated by rotary evaporation in vacuo to afford ˜7 g of crude 8-methylene-1,4-dioxaspiro[4.5]decane as a yellow liquid containing residual heptane.

Provenance & Evidence