ChemInform Abstract: PHOTOCHEMICAL REACTIONS. XIV. A NORRISH TYPE I CLEAVAGE IN THE PHOTOLYSIS OF A STEROIDAL α,β‐UNSATURATED Δ‐LACTONE

Abstract

SummaryThe UV. irradiation of 17/l-acetoxy-4-oxa-5 a-androst-1 -en-3-one (1) yields A, B-diseco-steroids originating from a Norrish I process of the lactone function.Introduction. -The photochemical behaviour of a ,P-unsaturated d-lactones has been mainly studied in coumarins [2]. In the monocyclic series, Matsuo et al. have reported addition of the solvent in the irradiation of 5,6-dihydro-6-methyl-2H-pyran-2-one [3]. Recently, we have been able to show that the 2-oxa-d4 and 4-oxasteroidal lactones undergo, respectively, the type A [4] and di-z-methane [5] photorearrangements in a similar way to their carbocyclic counterparts. In this paper we describe the results obtained in the irradiation of the A'-lactone 1.