ethanol; dodecacarbonyltetrarhodium(0) T=180°C; P=36775.4 Torr; 6 h;

1: pentan-3-one With tributyl-amine; titanium tetrachloride in dichloromethane T=-78°C; 2: methylglyoxylate methanol hemiacetal in dichloromethane T=-78 - 20°C; Further stages.;

hydrogenchloride in chloroform 0.25 h; Ambient temperature;

1: 57 percent / AlCl3 / CH2Cl2 / 1.) -20 deg C, 1 h, 2.) 0 deg C, 5 h 2: 78 percent / HCl(gas) / CHCl3 / 0.25 h / Ambient temperature View Scheme