Abstract
Irradiation of 5, 6β-dihydroxy-17β-acetoxy-5β-androstan-19-oic acid 5, 19-lactone (I) at room temperature using a mercury arc (450W) was found to yield in 30% yield 5, 6β-dihydroxy-17β-acetoxy-5α-androstan-19-oic acid 6, 19-lactone (II : R=Ac), structure of which was synthetically established. This photoreaction was proved to proceed through the keto-ketene intermediate (XV) generated upon irradiation of β-lactone moiety in I. On the other hand irradiation of 5-hydroxy-6-oxo-17β-acetoxy-5β-androstan-19-oic acid 5, 19-lactone (XIX) afforded 17β-acetoxyestra-5 (10) -en-6-one (XX) in about 60% yield.
