1: 80 percent / BF3*Et2O / 0.5 h / -75 °C View Scheme

1: 80 percent / BF3*Et2O / 0.5 h / -75 °C 2: toluene / 110 °C / sealed tube 3: p-TsOH*H2O / methanol / 16 h 4: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) -40 deg C, 15 min. 5: 15 h / Ambient temperature 6: 97 percent / BF3*Et2O / nitromethane / 0.42 h / Ambient temperature View Scheme

Multi-step reaction with 4 steps 1: 80 percent / BF3*Et2O / 0.5 h / -75 °C2: toluene / 110 °C / sealed tube3: p-TsOH*H2O / methanol / 16 h4: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) -40 deg C, 15 min.  

Multi-step reaction with 2 steps 1: 80 percent / BF3*Et2O / 0.5 h / -75 °C  

Multi-step reaction with 2 steps 1: 80 percent / BF3*Et2O / 0.5 h / -75 °C2: toluene / 110 °C / sealed tube  

Multi-step reaction with 3 steps 1: 80 percent / BF3*Et2O / 0.5 h / -75 °C2: toluene / 110 °C / sealed tube3: p-TsOH*H2O / methanol / 16 h  

Multi-step reaction with 5 steps 1: 80 percent / BF3*Et2O / 0.5 h / -75 °C2: toluene / 110 °C / sealed tube3: p-TsOH*H2O / methanol / 16 h4: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) -40 deg C, 15 min.5: 15 h / Ambient temperature