Sulfuric Acid → Acetophenone helveticosol

Participants

Reaction Steps

1.5 g. acetophenone-helveticoside are dissolved in 20 ml. of 80% aqueous dioxane and treated dropwise over a period of 1 hour with a solution of 0.35 g. sodium borohydride in 20 ml. of 75% dioxane. The reaction mixture is stirred for 1 hour, after which no more acetophenone-helveticoside can be detected. The solution is adjusted to pH 7 with dilute sulfuric acid, and the dioxane is removed under reduced pressure in a rotating evaporator. The aqueous phase is repeatedly extracted with chloroform. The combined chloroform extracts are dried over anhydrous sodium sulfate and evaporated. The residue is purified chromatographically over silica gel, using chloroform as solvent. Yield: 750 mg. acetophenone-helveticosol, melting point: 154°-164°C[αD20 ](C = 1, chloroform): ±0°.

Provenance & Evidence