1: 2.) Cr2O3 / 1.) AcOH, 25 deg C, 30 min; 2.) AcOH, water, 40 deg C, 2 h 2: 97 percent / 10 N HCl / ethanol / 2 h / Heating 3: 82 percent / pyridine / 1.) 0 deg C, 1 h; 2.) 20 deg C, 2 h View Scheme

in pyridine; chloroform

pyridine 1./ 3 h. 0 deg C. 2./ room temp. overnight.;