Photochemical reaction of 21-methyl-20,21-diketosteroids: The formation of new 3',4',16.ALPHA.,17.ALPHA.-tetrahydrocyclobut[16,17]androstanes.

Abstract

Exposure of 11β, 17α-dihydroxy-21-methylpregna-1, 4-diene-3, 20, 21-trione 17-acetate (Ia) and 17α-hydroxy-21-methylpregn-4-ene-3, 20, 21-trione 17-acetate (Ib) in EtOH to sunlight gave products having a new ring system in excellent yields, i.e., 3´, 4´, 16α, 17α-tetrahydro-4´ξ, 11β, 17α-trihydroxy-4´ξ-methylcyclobut [16, 17] androsta-1, 4, 16-triene-3, 3´-dione 17-acetate (IIa) and 3´, 4´, 16α, 17α-tetrahydro-4´, 17α-dihydroxy-4´ξ-methylcyclobut [16, 17] androsta-4, 16-diene-3, 3´-dione 17-acetate (IIb). The structures of the products were assigned on the basis of spectral data.