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

1: 65 percent / tert-butyl nitrite, sodium bis(trimethylsilyl)amide / toluene; tetrahydrofuran / 1.5 h / 50 °C 2: p-TsOH, paraformaldehyde / acetic acid / 5 h / 100 - 105 °C 3: 40 percent / t-BuOK / 2 h / 20 °C View Scheme