oxalic acid in tetrahydrofuran; water 15 h;

thallium(III) nitrate in methanol T=-25°C;

1: 86 percent / NaH / dimethylformamide / 0 °C 2: 73 percent / 1.) n-butyllithium / tetrahydrofuran / Ambient temperature; 1.) 1h, 2.) 2h 3: 67 percent / conc.HCl / ethanol / 2 h / Heating 4: 79 percent / Tl(NO3)3*3H2O / methanol / -25 °C View Scheme

1: 73 percent / 1.) n-butyllithium / tetrahydrofuran / Ambient temperature; 1.) 1h, 2.) 2h 2: 67 percent / conc.HCl / ethanol / 2 h / Heating 3: 79 percent / Tl(NO3)3*3H2O / methanol / -25 °C View Scheme

1: 67 percent / conc.HCl / ethanol / 2 h / Heating 2: 79 percent / Tl(NO3)3*3H2O / methanol / -25 °C View Scheme

aq acid in methanol according to ref. 9.;