Novel secosteroids arising from acid catalysed rearrangement of fluocinonide acetonide in the presence of Tf2O and TMSOTf

Article abstract of DOI:10.1016/S0040-4020(98)01172-7

Treatment of 6α,9α-difluoro-11β,21-dihydroxy-3,20-dioxo-16α, 17α- isopropylidenedioxypregna-1,4-diene-21-yl acetate (fluocinonide acetonide) with trifluoromethanesulfonic anhydride in the presence of trimethylsilyl trifluoromethanesulfonate as catalyst gave the ketone 3 and furan 4 arising from cleavage of the C9-C10 bond and aromatisation of the A ring, and fluocinonide 5. The ketone 3 was shown to be an intermediate in the formation of furan 4.