Lumisterol

Lumisterol is a compound that is part of the vitamin D family of steroid compounds. It is the (9β,10α) stereoisomer of ergosterol and was produced as a photochemical by-product in the preparation of vitamin D₁, which was a mixture of vitamin D₂ and lumisterol. Vitamin D₂ can be formed from lumisterol by an electrocyclic ring opening and subsequent sigmatropic [1,7] hydride shift.