J. Williams, Richard H. Moore, R. Li
Aug 1, 1979
Citations
0
Influential Citations
17
Citations
Journal
Journal of the American Chemical Society
Abstract
The photolysis o f prednisone acetate ( l b ) in dioxane yielded lumiprednisone acetate (Zb) and not the previously proposed structure 3. Further photoisomerization o f 2b in dioxane gave 2 1 -acetoxy-2, I7a-d ihydroxyI m e t h y l 19-norpregna1,3,5( IO)-trieneI I ,20-dione ( lob) . Irradiat ion o f 2b in 45% aqueous acetic acid yielded 2 I -acetoxy-l I a, I7a-d ihydroxyIp.1 Ifi-oxa-IOa-pregna-2,20-dione (14a), which has added a molecule o f water. S imi lar results were observed when prednisone was irradiated. Treatment o f 2b with acid afforded 17a,21 -dihydroxyI ( I 0 SP)-abeo-pregnaI ,9-diene-3, I 1,20-trione (15). The mechanism o f these photoisomerization reactions i s discussed. The influence o f solvents and the I I -keto function on the photochemistry of the bicyclo[3. I .O]hex-3-en-2-one system is explained. Barton and Taylor investigated the photochemistry of prednisone acetate ( l b ) more than 20 years ago, and reported its conversion into a range of novel molecules depending upon the reaction conditions.’ Since their structure, 3, for “lumiprednisone acetate” differed from that expected, 2b, based on the now generally accepted mechanism for photoisomerization of cross-conjugated die none^,^ it was decided to reinvestigate the photochemistry of the medicinally important prednisone ( la ) , its 21-acetate, lb, and their respective lumiproducts, 2a and 2b. Secondly, since photoisomerization reactions of 1,4cyclohexadienones are extremely sensitive to changes in s t r ~ c t u r e , ~ we were also interested in studying the effect of ring