1: 92 percent / POCl3, H2O / dimethylformamide / Vilsmeier reaction 2: ethanol / 1 h / Ambient temperature 3: sodium borohydride / Heating 4: 51 percent / CuCl 5: 89 percent / POCl3, H2O / dimethylformamide / Vilsmeier reaction View Scheme

water; trichlorophosphate in N,N-dimethyl-formamide Vilsmeier reaction;