1: 36 percent / CSA / CH2Cl2 2: 1) (C6H11)2NMgBr / 1) THF, -55 deg C, 2) THF, -55 to -30 deg C, 1.2 h 3: 85 percent / DDQ / CH2Cl2; H2O / 0.17 h / Ambient temperature 4: 61 percent / TFA, mol. sieves 3A / CH2Cl2 / 0.33 h / Ambient temperature View Scheme