131791-19-0Relevant academic research and scientific papers
Competing pathway involved in allylic acetoxylation of androst-5-en-17-one, and oxidation of allylic alcohols with chromium oxides
Numazawa, Mitsuteru,Tachibana, Mii,Kamiza, Miyako
, p. 569 - 575 (2007/10/03)
Allylic acetoxylation of androst-5-en-17-one (1) with bromine and silver acetate gave 6α- and 6β-acetoxyandrost-4-en-17-ones and 5α-bromo-6β-acetoxy steroid 8 (4percent) along with the expected product 4β-acetoxy derivative 2 (45percent).Treatment of 5α,6β-bromide 12, an intermediate of the acetoxylation reaction, with silver acetate also produced the acetates 2,4,5,and 8 in relative yields similar to those above.These results indicate that the 6=acetates 4 and 5 are produced through a competing pathway involving formation of a bridged carbonium ion 13 followed by attack of an acetate anion.Oxidation of the axial allylic alcohol, 5-en-4β-ol 3, with Jones reagent yielded no trace of the previously reported androst-5-ene-4,17-dione (18) but instead gave a 1:4 mixture of 5β,6β-epoxy-4-one 16 and 4β,5β-epoxy-6-one 17 in high yield.In contrast, a 1:4 mixture of androst-4-ene-6,17-dione (10) and compound 18 was obtained upon treatment with chromium trioxide in pyridine.Similar results were also found with the oxidation of another axial allylic alcohol, 4-en-6β-ol 7. (Steroid 60:499-505, 1995)
1:3-Rearrangement of Steroidal Allylic Acetoxy Groups during Epoxidation
Flaih, Nazar,Hanson, James R.
, p. 2667 - 2669 (2007/10/02)
Epoxidation of both 4β-acetoxyandrost-5-en-17-one and 6β-acetoxyandrost-4-en-17-one by m-chloroperbenzoic acid affords a similar mixture of 4β-acetoxy-5α,6α-epoxy- and 6β-acetoxy-4α,5α-epoxyandrostan-17-one.This is interpreted in terms of a symmetrical 'acetoxylinium' (1,3-dioxan-2-ylium) ion and a degree of charge separation in the transition state for epoxidation.
