Studies on vitamin D and related compounds XXII: New reactions and products in vitamin D₃ photochemistry

Abstract

Abstract From the mixtures resulting from U.V. irradiation (λ > 250 nm) of solutions of vitamin D 3 in ethanol four novel products could be isolated besides suprasterols 3 I and II. The NMR and other data suggest that two of the new compounds found are stereoisomeric vinylallene derivatives, whereas the two others may represent cyclobutene derivatives (Fig. 3). The six photoproducts of vitamin D 3 correspond to what would be expected from a 1,3,5‐hexatriene occurring in a s‐trans ‐Δ 3 ‐ cis‐s‐cis conformation.