Hydrochloric Acid → 5,5-Dimethyl-3-prop-2-ynyl-3-trifluoromethyl-1,3,4,5-tetrahydrobenzo[c]oxepin-1-ol

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Reaction Conditions

Reaction Steps

A solution of 3-(5,5-dimethyl-3-prop-2-ynyl-3-trifluoromethyl-1,3,4,5-tetrahydrobenzo[c]oxepin-1-yloxy)propan-1-ol (15.0 g) in THF (150 mL) was treated with 1M aqueous HCl (75 mL) and heated at 40° C. for 16 hours. The volatiles were then removed in vacuo and the aqueous layer extracted with ethyl acetate (300 mL), washed with two 100 mL portions of saturated aqueous sodium bicarbonate solution, dried over magnesium sulfate, filtered, and concentrated in vacuo. The crude was purified by flash chromatography (300 g SiO2, hexanes to 4:1 hexanes:EtOAc) to give 5,5-dimethyl-3-prop-2-ynyl-3-trifluoromethyl-1,3,4,5-tetrahydrobenzo[c]oxepin-1-ol (5.75 g, 46%) as a 1:1 mixture of lactol and aldehyde by NMR. The mixture was used without further purification in the next transformation.

Provenance & Evidence