1: 97 percent / LDA / tetrahydrofuran; various solvent(s) / 1.) -78 deg C, 1h, 2.) -78 deg C, 1 h, -78 deg C to 0 deg C, 2 h 2: 80 percent / LDA / tetrahydrofuran; various solvent(s) / 1.) -78 deg C, 2 h, 2.) -78 deg C, 1h 3: 1.) t-BuLi, 2.) n-Bu4NH2PO4 / 1.) THF, -78 deg C, 1 h, 2.) H2O, reflux, 12 h 4: NaOEt / ethanol / 24 h / Heating View Scheme

1.1: lithium diisopropylamide / tetrahydrofuran / 1 h / -18 °C 1.2: 95 percent / oxalic acid / tetrahydrofuran; H2O / 0 - 27 °C 2.1: NaI; TMSCl; (TMS)2NH / acetonitrile / 4 h / 0 °C 2.2: 80 percent / N-bromosuccinimide / tetrahydrofuran / 14 h / -18 - 23 °C View Scheme