1: 1) DMSO, (COCl)2, 2) Et3N / 1) CH2Cl2, -78 deg C, 2) CH2Cl2, -78 to -15 deg C 2: 36 percent / CSA / CH2Cl2 3: 1) (C6H11)2NMgBr / 1) THF, -55 deg C, 2) THF, -55 to -30 deg C, 1.2 h 4: 85 percent / DDQ / CH2Cl2; H2O / 0.17 h / Ambient temperature 5: 61 percent / TFA, mol. sieves 3A / CH2Cl2 / 0.33 h / Ambient temperature View Scheme