1: With sodium methylsulfinylmethanide in tetrahydrofuran; dimethyl sulfoxide T=-14°C; 0.25 h; 2: With ethyl 2-ethoxycarbonyl-3-dimethyl(phenyl)silyl-2-propenoate in tetrahydrofuran; dimethyl sulfoxide T=-8 - 20°C; Sommelet-Hauser rearrangement; 2 h;

(hydrotris(3-mesityl)pyrazolylborate)Cu(tetrahydrofuran); N-benzyl-N,N,N-triethylammonium chloride T=60°C; 4 h; Inert atmosphere;

phosphoranylidene phosphoric triamide ethylimine derivative in dichloromethane T=0°C; 18 h;

1.1: hexane / Heating 2.1: sodium dimsylate / dimethylsulfoxide; tetrahydrofuran / 0.25 h / -14 °C 2.2: 82 percent / PhMe2SiC=C(CO2Et)2 / dimethylsulfoxide; tetrahydrofuran / 2 h / -8 - 20 °C View Scheme