1: (+/-)-2-oxocyclohexanepropionic acid With chloroformic acid ethyl ester; triethylamine in diethyl ether T=20°C; 0.75 h; 2: diazomethane in diethyl ether T=0 - 10°C; 14 h;

1.1: 7.6 g / dioxane / 12 h / Heating 2.1: 90 percent / potassium hydroxide / H2O / 4 h / 20 °C 3.1: ethyl chloroformate; triethylamine / diethyl ether / 0.75 h / 20 °C 3.2: 53 percent / diethyl ether / 14 h / 0 - 10 °C View Scheme

1.1: p-toluenesulfonic acid / benzene / Heating 2.1: 7.6 g / dioxane / 12 h / Heating 3.1: 90 percent / potassium hydroxide / H2O / 4 h / 20 °C 4.1: ethyl chloroformate; triethylamine / diethyl ether / 0.75 h / 20 °C 4.2: 53 percent / diethyl ether / 14 h / 0 - 10 °C View Scheme

titanium tetrachloride in dichloromethane T=0°C; 0.0333333 h;

tin(ll) chloride in dichloromethane Ambient temperature;

1: <Et3O>BF4 / CH2Cl2 2: (i) NaH, benzene, (ii) /BRN= 969135/ View Scheme