During the hydrogenation of the Δ3(3a)-4-hydrindenones or on Pd or Ni, we observe a shift of the double bond to Δ3a(7a)-4-hydrindenones and . The absolute configuration established for ketones and shows that the reaction is a suprafacial process. By deuteriation experiments, we observe that the reaction is irreversible and occurs with a molecular hydrogen exchange.
Radical-induced epoxide fragmentation chemistry. n-Bu3Sn· radical catalyzed isomerization of epoxyketones to carbocycles
作者:Viresh H. Rawal、Venkat Krishnamurthy、Agnes Fabre
DOI:10.1016/s0040-4039(00)60475-6
日期:1993.4
Cyclic alpha,beta-epoxyketones are converted to bi- or tricyclic beta-hydroxyketones in the presence of n-Bu3Sn. radical. Addition of n-Bu3Sn. to the carbonyl group gives a ketyl radical that triggers the epoxide fragmentation which is then followed by a 1,5-hydrogen abstraction and cyclization. Reversibility in the last two steps of the sequence is demonstrated.