Ethylene Glycol → 5'-bromo-3',4'-dihydro-1'H-spiro[[1,3]-dioxolane-2,2'-naphthalene]

Participants

Reaction Steps

3′,4′-Dihydro-1′H-spiro[[1,3]dioxolane-2,2′-naphthalene]-5′-carbaldehyde, designated as 37 in FIG. 15, was prepared as follows: A solution of 5-bromo-3,4-dihydronaphthalen-2(1H)-one (625 mg, 2.78 mmol), ethylene glycol (0.23 mL, 4.17 mmol), and p-toluenesulfonic acid (5.70 mg, 0.03 mol) in benzene (46 mL) was stirred and heated to reflux for 10 h. The solution was cooled, diluted with ether, and sequentially washed with saturated aqueous sodium bicarbonate solution and water. The organic layer was dried over magnesium sulfate, filtered and concentrated in vacuo. Purification by silica gel column chromatography, using a 2:1 mixture of hexanes and AcOEt as eluant, furnished 5′-bromo-3′,4′-dihydro-1′H-spiro[[1,3]-dioxolane-2,2′-naphthalene](730.4 mg, 98% yield) as a yellow oil. Yield: 65%.

Provenance & Evidence