1.1: sodium iodide / acetone 2.1: N,N,N',N',N'',N''-hexamethylphosphoric triamide; n-butyllithium / tetrahydrofuran / -78 °C 2.2: -78 °C / Heating 3.1: hydrogen / 760.05 Torr 4.1: toluene-4-sulfonic acid / methanol 5.1: dipyridinium dichromate / N,N-dimethyl-formamide View Scheme