In this report, a generalmethod for the preparation of 1,5-dicarbonyl compounds and six membered ring annelation is described. This method involves the reaction of hemiacetal vinylogs 1 with enol ethers 2 or 3 in the presence of a Lewis acid. This reaction was successfully applied to the enol ethers of α and α,α'-hindered ketones such as 2,2,6-trimethyl cyclohexanone. α-Cyperone and 6-epi-α-cyperone
Synthesis of bicyclic aza-enones via a lewis acid catalysed Michael-type addition with silyl enol ethers bearing a nitrogen atom.
作者:Duhamel Pierre、Deyine Abdallah、Poirier Jean-Marie
DOI:10.1016/s0040-4039(00)79248-3
日期:1993.6
Silyl enol ethers bearing a nitrogen atom protected by an electron-withdrawing group give in high yield a Micheal-type addition with hemiacetal vinylog or a mixture of methyl vinyl ketone and an alcohol in the presence of borontrifluorideetherate as a catalyst. The aza-1,5-diketones so prepared can be cyclised leading to aza-enones precursors of some biologycally active structures.
cyclisation of the ketoaldehyde into azaspiroenone and nitrogen deprotection was performed in basic medium. The N-benzylation of this enone gave the known key intermediate of total synthesis of (±)-perhydrohistrionicotoxin.