1: ethyl acetoacetate With lithium diisopropyl amide in tetrahydrofuran; hexane T=0°C; Metallation; 0.75 h; 2: N-N'-dimethoxy-N-N'-dimethyloxaldiamide With N,N,N',N,-tetramethylethylenediamine in tetrahydrofuran; hexane T=-78 - 0°C; Cyclization; 5.5 h;

trifluoroacetic acid in dichloromethane T=-78 - 20°C; Cyclization; 20 h; Product distribution; Further Variations:Reagents;