orthoformic acid triethyl ester in hydrogenchloride; N,N-dimethyl-formamide 2 h; Ambient temperature;

1: 86 percent / ethyl orthoformate / aq. HCl; dimethylformamide / 2 h / Ambient temperature 2: 1) NaH / 1) DMF, 40 deg C, 30 min, 2) 100 deg C, 9 h 3: 82 percent / H2SO4 / H2O / 48 h / Ambient temperature View Scheme

sodium hydroxide in water 8 h; Heating;