1: 84 percent / H2SO4 / CH2Cl2 / 19 h / 20 °C 2: 99 percent / NaI / acetone / 72 h / Heating View Scheme

1.1: 84 percent / H2SO4 / CH2Cl2 / 19 h / 20 °C 2.1: 99 percent / NaI / acetone / 72 h / Heating 3.1: Zn; Me3SiCl / dimethylformamide / 20 °C 3.2: 34 percent / P(o-tol)3 / tris(dibenzylideneacetone)dipalladium / dimethylformamide / 4 h / 50 °C 4.1: 64 percent / Et3SiH; TFA / CH2Cl2 / 4 h / 20 °C View Scheme

sodium hydrogencarbonate in acetone T=20°C; 48 h;