1.1: 50 percent / oxalyl chloride; dimethyl sulfoxide; triethylamine / CH2Cl2 / -60 - 0 °C 2.1: pyridinium bromide perbromide / diethyl ether / 2 h / 20 °C 2.2: triethylanine / diethyl ether / 16 h / 20 °C 2.3: 47 percent / piperidine / diethyl ether / 24 h / 20 °C 3.1: 75 percent / NaOH / ethanol / 5 h / 20 °C 4.1: NaIO4 / acetone; H2O / 35 h 5.1: 60 percent / NaHCO3 / hexane; diethyl ether / 10 h / Heating View Scheme