1: diethyl phosphite / 2 h / 0 - 20 °C 2: lithium diisopropylamide / tetrahydrofuran / -78 °C 3: 79 percent / BuLi-CuI, TMEDA / tetrahydrofuran / 0.25 h / -78 °C 4: 2 h / Ambient temperature 5: 1.) LDA; 3.) 5percent hydrochloric acid / 1.) ether, -78 deg C, 0.5 h; 2.) -78 deg C to room temp. 3.) room temp., 2 h View Scheme

1: 79 percent / BuLi-CuI, TMEDA / tetrahydrofuran / 0.25 h / -78 °C 2: 2 h / Ambient temperature 3: 1.) LDA; 3.) 5percent hydrochloric acid / 1.) ether, -78 deg C, 0.5 h; 2.) -78 deg C to room temp. 3.) room temp., 2 h View Scheme

1: 2 h / Ambient temperature 2: 1.) LDA; 3.) 5percent hydrochloric acid / 1.) ether, -78 deg C, 0.5 h; 2.) -78 deg C to room temp. 3.) room temp., 2 h View Scheme

hydrogenchloride; lithium diisopropyl amide 1.) ether, -78 deg C, 0.5 h; 2.) -78 deg C to room temp. 3.) room temp., 2 h; Yield given. Multistep reaction;