1.1: BuLi / tetrahydrofuran / 0.75 h / -78 °C 1.2: 1.33 g / tetrahydrofuran / 12 h / 20 °C 2.1: aq. KOH / methanol / 12 h 3.1: 1.25 g / [2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium]*BF4; (i-Pr)2NEt / CH2Cl2 / 12 h 4.1: BuLi / hexane; tetrahydrofuran / 0.25 h / -78 °C 4.2: 64 percent / hexane; tetrahydrofuran / -78 - 20 °C View Scheme