1: N,N'-dimethyl-N,N'-propyleneurea; lithium diisopropyl amide / tetrahydrofuran / -40 - 0 °C / |Inert atmosphere 2: tetrabutyl ammonium fluoride / tetrahydrofuran / 0 °C / |Inert atmosphere 3: 1-methyl-1H-imidazole / tetrahydrofuran / 0 °C / |Inert atmosphere 4: 1,10-phenanthroline; n-butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C / |Inert atmosphere View Scheme