Cholesterol Phenylacetate is a sterol ester that characterized by the presence of a double bond in the B ring of the steroid nucleus and an additional double bond on the phenylacetate side chain. Cholesterol phenylacetate was subjected to epoxidation using trans-dioxoruthenium(VI) tetramesitylporphyrin as a catalyst and air as the source of oxygen. The results showed that Cholesterol Phenylacetate underwent selective epoxidation at the steroid nucleus, specifically at the 5,6 position. The epoxidation reaction was highly regioselective, yielding predominantly the 5,6β-epoxide with a yield of 88% within 2 hours[1].
References:
[1] Tavares M, Ramasseul R, Marchon J C. Regioselective epoxidation by air of sterol esters bearing several double bonds using a ruthenium porphyrin cataltyst. Catalysis Letters 4 (1990) 163-168.