1.1: B(OMe)3 / diethyl ether / -25 - 20 °C 1.2: 5 percent HCl / diethyl ether 1.3: 58 percent / K[HF2] / methanol; H2O / 20 °C 2.1: BF3 / CH2Cl2 / -50 - -40 °C View Scheme

in dichloromethane (Ar), at -40/-50°C for 15-25 min; degassed (vac., -78°C), phases sepd., solid washed with CH2Cl2, exts. combined; not isolated, detected by NMR;