Addition of dienolates to sulfinimines. Stereoselective synthesis of dihydropyridones

The vinylogous Mannich reaction of sulfinimines with dienolates was investigated. Lithium and trimethylsilyl enolates of ethyl 3-ethoxycrotonate reacted with enantiopure 10-isobornylsulfinimines to give derivatives of δ-aminoacids which were cyclised to 6-aryl substituted derivatives of 2(1H)-pyridinones. 6-Aryl substituted 2,4-piperidinediones with either (S) or (R) configuration were analogously obtained using lithium and TMS enolates of 2,2,6-trimethyl-1,3-dioxin-4-one.