Synthesis of steroidal azides. Part 2. Reaction of 4,6-dien-3-ones with lead tetra-acetate and trimethylsilyl azide

Abstract

The reaction of steroidal 4,6-dien-3-ones with lead tetra-acetate and trimethylsilyl azide is shown to give predominantly 6β,7α-diazido-4-en-3-ones together with minor amounts of 7α-azido-4-ene-3,6-diones. With lead tetra-acetate and a mixture of trimethylsilyl azide and trimethyl silyl bromide, the same substrates yield exclusively 7α-azido-6β-bromo-4-en-3-ones. Reaction mechanisms are proposed to interpret these results. The 6β,7α-diazido-4-en-3-ones may be readily converted into 6-azido-4,6-dien-3-ones.