1: 77 percent / phosphoryl chloride / 24 h / Ambient temperature 2: tert-butyl nitrite, t-BuOK / toluene / 1 h / Ambient temperature 3: 67.6 percent / conc. H2SO4 / 5 h View Scheme

1: 77 percent / phosphoryl chloride / 24 h / Ambient temperature 2: tert-butyl nitrite, t-BuOK / toluene / 1 h / Ambient temperature 3: 60.7 percent / p-TsOH, paraformaldehyde / acetic acid / 5 h / Heating 4: t-BuOK / 2 h / Ambient temperature View Scheme