Novel rearrangement of 5,6-disubstituted bicyclo[4.2.0]octan-2-ones with aluminum chloride. Application to total synthesis of (.+-.)-5-oxosilphiperfol-6-ene and (.+-.)-silphiperfol-6-ene
Mannich bases react thermally with ketones to give 1,5-diketones by what appears to be a Michael reaction. In some cases the orientation of the product differs significantly from that observed in the Michael reaction, and Mannich bases lacking a hydrogen β to the N atom are able to react via an intermediate migration.
Novel rearrangement of 5,6-disubstituted bicyclo[4.2.0]octan-2-ones with aluminum chloride. Application to total synthesis of (.+-.)-5-oxosilphiperfol-6-ene and (.+-.)-silphiperfol-6-ene